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https://ptreview.sublinear.info/?p=949 | # News for January 2018
And now, for the first papers of 2018! It’s a slow start with only four papers (or technical three “standard property testing” papers, and one non-standard paper).
Adaptive Boolean Monotonicity Testing in Total Influence Time, by Deeparnab Chakrabarty and C. Seshadhri (arXiv ECCC). The problem of testing monotonicity of Boolean functions $$f:\{0,1\}^n \to \{0,1\}$$ has seen a lot of progress recently. After the breakthrough results of Khot-Minzer-Safra giving a $$\widetilde{O}(\sqrt{n})$$ non-adaptive tester, Blais-Belovs proved the first polynomial lower bound for adaptive testers, recently improved to $$O(n^{1/3})$$ by Chen, Waingarten, and Xi. The burning question: does adaptivity help? This result shows gives an adaptive tester that runs in $$O(\mathbf{I}(f))$$, the total influence of $$f$$. Thus, we can beat these lower bounds (and the non-adaptive complexity) for low influence functions.
Adaptive Lower Bound for Testing Monotonicity on the Line, by Aleksandrs Belovs (arXiv). More monotonicity testing! But this time on functions $$f:[n] \to [r]$$. Classic results on property testing show that monotonicity can be tested in $$O(\varepsilon^{-1}\log n)$$ time. A recent extension of these ideas by Pallavoor-Raskhodnikova-Varma replace the $$\log n$$ with $$\log r$$, an improvement for small ranges. This paper proves an almost matching lower bound of $$(\log r)/(\log\log r)$$. The main construction can be used to give a substantially simpler proof of an $$\Omega(d\log n)$$ lower bound for monotonicity testing on hypergrids $$f:[n]^d \to \mathbb{N}$$. The primary contribution is giving explicit lower bound constructions and avoiding Ramsey-theoretical arguments previously used for monotonicity lower bounds.
Earthmover Resilience and Testing in Ordered Structures, by Omri Ben-Eliezer and Eldar Fischer (arXiv). While there has been much progress on understanding the constant-time testability of graphs, the picture is not so clear for ordered structures (such as strings/matrices). There are a number of roadblocks (unlike the graph setting): there are no canonical testers for, say, string properties, there are testable properties that are not tolerant testable, and Szemeredi-type regular partitions may not exist for such properties. The main contribution of this paper is to find a natural, useful condition on ordered properties such that the above roadblocks disappear hold, and thus we have strong testability results. The paper introduces the notion of Earthmover Resilient properties (ER). Basically, a graph properties is a property of symmetric matrices that is invariant under permutation of base elements (rows/columns). An ER property is one that is invariant under mild perturbations of the base elements. The natural special cases of ER properties are those over strings and matrices, and it is includes all graph properties as well as image properties studied in this context. There are a number of characterization results. Most interestingly, for ER properties of images (binary matrices) and edge-colored ordered graphs, the following are equivalent: existence of canonical testers, tolerant testability, and regular reducibility.
Nondeterminisic Sublinear Time Has Measure 0 in P, by John Hitchcock and Adewale Sekoni (arXiv). Not your usual property testing paper, but on sublinear (non-deterministic) time nonetheless. Consider the complexity class of $$NTIME(n^\delta)$$, for $$\delta < 1$$. This paper shows that this complexity class is a "negligible" fraction of $$P$$. (The analogous result was known for $$\alpha < 1/11$$ by Cai-Sivakumar-Strauss.) This requires a technical concept of measure for languages and complexity classes. While I don’t claim to understand the details, the math boils down to understanding the following process. Consider some language $$\mathcal{L}$$ and a martingale betting process that repeatedly tries to guess the membership of strings $$x_1, x_2, \ldots$$ in a well-defined order. If one can define such a betting process with a limited computational resource that has unbounded gains, then $$\mathcal{L}$$ has measure 0 with respect to that (limited) resource. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8728532791137695, "perplexity": 1010.247723227218}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-34/segments/1534221216453.52/warc/CC-MAIN-20180820121228-20180820141228-00136.warc.gz"} |
http://emotional-calculus.wikidot.com/paedagogy | Paedagogy
This is probably one of the most important things to think about.
There are two aspects of paedagogy: initial knowledge, and current affairs. Consider television news bulletins. They assume a certain amount of existing knowledge - what a country is, what money is, where the United States is, how to understand spoken English, and so on. This is all a base of knowledge needed to understand the rest. Children need to be taught all of this. The initial knowledge is constantly updated with new knowledge.
Paedagogy extends the human being. Current affairs extend the senses - as well as seeing what is going on in one's immediate environment, one knows what is going on all over the world. Initial knowledge extends the memory of one's own life - now one knows about the history of the world which is the background to current affairs.
We should give careful thought to what should be the substance of both forms of paedagogy. We would like to present to children an account of how they came to be, viewing the whole universe as an extension of their bodies. This would be an outlook passed on through the generations. The accuracy of the outlook would depend on how long it took to learn. At the moment, children spend about twelve years in school, so we should look for the best presentation of facts that would take twelve years. At the moment, school lessons are very divided into different subjects. They ought to support and reinforce each other, as part of a single presentation. The key word here is holism.
# Methods
A lot of the time when someone is trying to learn about something by reading a text they are trying to get sparks of understanding to occur in their mind when they are doing it. To know what this means, these sparks of understanding are what you are missing when you have read too much and your brain is tired and you can't make sense of anything, even parse one sentence.
Presentation of knowledge should reflect an internal representation and be as compact as possible. Diagrams should be used when possible. Looking at a diagram one can directly see the fact and doesn't have to use mental effort in constructing one's own mental image.
We'd like a collection of such presentations, that could cover a wide variety of relations: such as sequences, family trees, saying that one thing is a special case of another, and so on
Wikipedia is probably the closest thing at the moment to something you can use to explore the totality of knowledge. Interactive computer programs are the future of paedagogy, I think. One will be able to sit back and browse a body of knowledge, looking at what is found immediately interesting and slowly soaking knowledge into the brain.
I would like to think that this is true of even complicated and difficult bodies of knowledge, like mathematics or foreign languages. In hindsight, looking back at lecture notes, a lot of it is wordier than it needs to be and there aren't actually that many basic ideas. A good project for me could be to try to produce some mathematical educational videos, and see how easy it could be to put across understanding. It is my opinion that anything should be easy to learn if it is learnt slowly enough. What's 'hello' in Turkish? Well gee, I don't know. I saw it yesterday but forgot it instantly. But that would be an interesting fact. After I knew that, what 'goodbye' and 'thank you' are would be the next most interesting facts. This could gradually segue into knowledge of orthography and grammar. Once a larger body of vocabulary is built up, it's easier to learn more vocabulary, because every word in the language balances against every word in the language that is known, in distinction to it. (There are potential connections here between each and every word, but I'm not sure what connections should be included in a formal, electronic representation. I'd have to try making a system and cross such bridges when I came to them.)
I should point out that a body of knowledge is a collection of related facts. If I think about the family tree of my extended family, I don't hold it all in my head at the same time. If I were to represent this knowledge visually, and it was inconvenient and messy to have one large diagram, with each person occurring exactly once in it, containing all the relevant information about the relations between people, then actually nothing would be lost by splitting it into smaller trees ('facts'). I could have my parents and any siblings in a two-level tree. Then the same could be done for each of my parents along with their parents. Any uncles or aunts with their children (my cousins) could occur similarly. The aim is to represent basic facts and basic relations between them, which are very simple. I can't quickly guess the number of a collection of objects if the number is more than three, so basic concepts can't be much more complicated than including three entities. I think some 'concept maps' or 'mind maps' have gone wrong here - massive, complicated diagrams full of overlapping arrows pointing in all directions that one can't make nor tail of.
Okay, I shrank this on purpose
# Interest
It is a basic paedagogical principle that examples make learning easier. Consider the following sound changes that occured in Early Middle English, taken from Wikipedia's page on the phonological history of English:
• /æː/ and /ɑː/ became /ɛː/ and /ɔː/
• /æ/ and /ɑ/ merged into /a/
• /ʏ/ and /yː/ were unrounded to /ɪ/ and /iː/
• /ɣ/ became /w/ or /j/, depending on surrounding vowels
Umm… fascinating?! What is missing is examples and context. If I may make a diversion into the science of thought, I would say that interest is a biological property. One may wish to learn a body of language, and this is his broad, overriding wish, but still find it difficult to get individual facts into his head. The biological level of interest is immediately felt when one sees a fact, and this reflects that this fact is easily incorporated into his memory - his body of knowledge, thoughts, dreams and beliefs - by virtue of the relations it has with what is already known. In order to learn a large body of knowledge, it is necessary to jam in boring facts just to get the interest started. (In fact, disciplined learning and study remains important, as others in society are capable of doing the same, giving an extra edge to what can be learnt and understood.) These sound changes are only interesting if one knows what words they occurred in. If I knew what words today were descended from words that had [ʏ] at one point but later had [ɪ] then I might actually be able to remember that information. I might be able to build up a complete picture of the historical development of the English language. As it is, it is empty and meaningless information which I have no biological interest in obtaining. (For example, one fact which would make one of the above facts interesting is that the unrounding of /ʏ/ and /yː/ explains why "i" and "y" represent the same sound in English spelling. I'm not 100% sure but I think the merger of /æ/ and /ɑ/ is reflected in the fact that Modern English does not have a letter "æ" whereas Old English had both "æ" and "a". For the last one, I think "year" used to be spelled "gear" or something similar. I remember reading that we know that the word "get" comes from Old Norse because if it came from Old English it would be "yet". Also "warden" and "guardian" have a common root, they came from two different dialects of French. These are examples of "g" being replaced with "w" and "y" respectively, even if they aren't examples of the specific change above. So without being precise, you can relate these facts to things you already know.)
To learn a foreign language, first you learn a few words and phrases. Maybe later you learn about different noun declensions, different systems of making plurals, different systems for making sentences to talk about past time, and so on. You wouldn't start off by memorizing tables of verb endings, or different forms of the definite article.
Things affecting interest:
• Relevance to facts already known
• Length of exposition (the shorter the better), or how easy it is to understand
• Whether it will complete a body of knowledge — is it the 'missing piece' in the jigsaw. This is one of the benefits of learning from a fixed, written exposition, such as a vocabulary list or a set of lecture notes — it is possible to learn the whole thing, and any parts of it which haven't been learned are interesting because they will complete the knowledge of the exposition.
• Is it seen to help in the understanding of other things? If there is another system which uses some elements from a first, then reading about the second system, a learner will have his interest in the first system increase.
• Does it bring painful or joyful thoughts to mind? Someone might find it hard to learn about spiders if they were terrified or disgusted by them.
• There also has to be a motivation. I thought of learning the first 81 digits of $\pi$ by structuring it into 3 groups of 3 groups of 3 groups of 3, and learning each group as a block in relation to other blocks. I failed because I wasn't interested. As well as an accessible structure there has to be motivation. The greater the motivation the greater the information content can be. If you aren't very interested, a summary of the subject will suffice.
• Of course this isn't a good example because you would tend to get the blocks confused with each other. A better example would be memorizing a street map - first memorizing the main streets, and then using that as a foundation for memorizing the side streets.
Interest is very related to the experience of finding something difficult. If you try to do something or learn something, you will find some parts easy, and some difficult. If you come back the next day, you will be interested or receptive to learning whatever it was you found difficult the previous day. It is like this for learning a language - if you read a lot of text in the language, and you encounter a word which gets in the way of understanding a lot, you will become receptive to the meaning of this word.
# The occasions of learning
Learning is clearly a process we go through, but what does it consist of and what does it feel like? Here are some conscious phenomena which are part of learning:
• Reading a fact for the first time.
• Having a fact come to mind (spontaneously coming from the subconscious)
• Asking oneself a question, being unable to remember the answer, and then looking up the answer
# Types of exposition
• Dictionary exposition — A methodical presentation of a body of knowledge. Has all the information, but is difficult to learn from. Examples are the dictionary — it is hard to learn new words by reading a dictionary, but easy to use it to look up information — and the Unix man page — it has all the information about the operation of the program and how it responds to different command line switches and options and environment variables, but it can be difficult to find out how to do a specific thing with them.
• Course exposition — A cruise through the oceans of knowledge, always keeping the learner's attention on new, interesting information relevant to what has gone before.
• Revision - Material can be revised in a different way from the way that it is learned initially. Notably, every fact is related to several other facts in the internal representation of knowledge. By revising one fact, the peripheral facts are revised as well. Additionally, a lot more material can be covered in revision. You could easily skim a list of a hundred words in a foreign language if you already knew them, but trying to memorize the same list would not be the most efficient way of learning them in the first place.
# Self-paedagogy and the interpretive cycle
One problem with trying to learn about the world is that you use your prior knowledge in interpreting texts, for example in judging how trustworthy or insightful they are. Learning from these updates your knowledge which leads you on to interpret differently in the future.
page revision: 21, last edited: 22 Apr 2012 14:31 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.3865693211555481, "perplexity": 640.6275569615309}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-34/segments/1534221215487.79/warc/CC-MAIN-20180820003554-20180820023554-00252.warc.gz"} |
https://homework.cpm.org/category/CCI_CT/textbook/calc/chapter/9/lesson/9.1.2/problem/9-28 | ### Home > CALC > Chapter 9 > Lesson 9.1.2 > Problem9-28
9-28.
Note: The following steps outline the washer method. The answer in the back of the book uses the shell method.
Always start by sketching a graph of the situation.
If you are rotating about the y-axis, will the radii be horizontal or vertical?
Since rotation is about the y-axis, the integral will have dy.
Now, determine the bounds of integration.
Determine which function is the outside function and which is the inside function for the solid.
Then, using the washer method, set up the integral as:
$\int_a^b \pi((r_\text{outide})^2-(r_\text{inside})^2)dy$ | {"extraction_info": {"found_math": true, "script_math_tex": 1, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7980761528015137, "perplexity": 574.2889459329343}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-10/segments/1614178358976.37/warc/CC-MAIN-20210227144626-20210227174626-00441.warc.gz"} |
https://mijn.bsl.nl/toddler-screening-for-autism-spectrum-disorder-a-meta-analysis-o/16386636?fulltextView=true&doi=10.1007%2Fs10803-018-03865-2 | main-content
## Swipe om te navigeren naar een ander artikel
08-01-2019 | OriginalPaper | Uitgave 5/2019 Open Access
# Toddler Screening for Autism Spectrum Disorder: A Meta-Analysis of Diagnostic Accuracy
Tijdschrift:
Journal of Autism and Developmental Disorders > Uitgave 5/2019
Auteurs:
Ana B. Sánchez-García, Purificación Galindo-Villardón, Ana B. Nieto-Librero, Helena Martín-Rodero, Diana L. Robins
Belangrijke opmerkingen
## Electronic supplementary material
The online version of this article (https://doi.org/10.1007/s10803-018-03865-2) contains supplementary material, which is available to authorized users.
## Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Population level (level 1) screening for autism spectrum disorder (ASD) has been the subject of numerous papers, particularly since the American Academy of Pediatrics published a policy statement more than a decade ago (Council on Children with Disabilities 2006). The most commonly studied tool is the Modified Checklist for Autism in Toddlers (M-CHAT; Robins et al. 1999), and its revision, the M-CHAT-revised, with follow-up (M-CHAT-R/F; Robins et al. 2009). However, the variety of screening tools for prospective identification of early signs of autism has encouraged the publication of different systematic reviews (Daniels et al. 2014; McPheeters et al. 2016). See Table 1 for the tools included in the current meta-analysis, and references for more information about each tool.
Table 1
Details of sample characteristics and individual outcomes such as studies show
Study number
Screening test(s)
Country
FN a strategy
FN
FP
TP
TN
N
Total N b
Sex
Not reported
Age (months)
Female
Male
1. Nygren et al. ( 2012)
M-CHAT
Sweden
No
NA
3
33
NA
3.985
3.999
2.087
1.912
NA
29.00
2. Nygren et al. ( 2012)
JOBS
Sweden
No
NA
3
37
NA
3.985
3.999
2.087
1.912
NA
29.00
3. Nygren et al. ( 2012)
M-CHAT + JOBS
Sweden
No
NA
5
43
NA
3.985
3.999
2.087
1.912
NA
29.00
4. Baird et al. ( 2000)
CHAT
UK
Yes
74
14
20
16.127
16.235
NA
NA
NA
NA
18.70
5. Wiggins et al. ( 2014)
M-CHAT
USA
Yes
3
17
27
3.803
3.850
3.980
NA
NA
NA
21.10
6. Wiggins et al. ( 2014)
PEDS+ PATH
USA
Yes
2
20
28
2.978
3.028
3.980
NA
NA
NA
21.10
7. Kamio et al. ( 2014)
M-CHAT_JV
Japan
Yes
22
24
20
1.661
1.727
2.141
880
847
NA
18.70
8. Stenberg et al. ( 2014)
M-CHAT
Norway
Yes
114
3.804
59
48.049
52.026
NA
25.429
26.597
NA
18.00
9. Chlebowski et al. ( 2013)
M-CHAT/Yale Screener + STAT
USA
Yes
6
79
92
18.269
18.446
18.989
9.388
9.601
NA
20.40
10. Canal-Bedia et al. ( 2011)
M-CHAT
Spain
Yes
0
25
6
2.024
2.055
NA
949
1.106
NA
21.40
11. Barbaro and Dissanayake ( 2010)
SACS
Australia
Yes
34
41
174
20.521
20.770
NA
10.177
10.593
NA
19.27
12. Inada et al. ( 2011)
M-CHAT (short version 9, cut-off 1)
Japan
NA
NA
NA
20
NA
1.167
1.187
571
596
NA
18.00
13. Inada et al. ( 2011)
M-CHAT (full version)
Japan
NA
NA
NA
20
NA
1.167
1.187
571
596
NA
18.00
14. Dereu et al. ( 2010)
CESDD
Belgium
Yes
13
265
28
6.502
6.808
NA
3.255
3.553
NA
16.70
15. Miller et al. ( 2011)
ITC + M-CHAT
USA
Yes
2
17
10
638
667
796
NA
NA
NA
NA
16. Robins et al. ( 2014)
M-CHAT-R/F
USA
Yes
18
116
105
15.373
15.612
16.071
7.570
7.793
249
20.95
17. Honda et al. ( 2005)
YACHT-18
Japan
Yes
16
NA
68
NA
35.716
NA
17.468
18.248
NA
18.00
18. Baranek ( 2015)
M-CHAT
USA
Yes
3
32
5
534
574
NA
300
268
6
24.73
FN false negative, FP false positive, TP true positive, TN true negative, NA not available from paper, M-CHAT modified-checklist for autism in toddlers, JOB joint attention-observation schedule, CHAT checklist for autism in toddlers, PED parents’ evaluation of developmental status, M-CHAT_JV modified-checklist for autism in Toddlers_Japanese version, STAT screening tool for autism in toddlers and young children, SACS social attention and communication study, CESDD checklist for early signs of developmental disorders, M-CHAT-R/ F modified checklist for autism in toddlers, revised, with follow-up, YACHT-18 young autism and other developmental disorders checkup tool
a FN strategy = methods to identify false negative screening cases, or children with ASD who were missed by the screening tool(s) of interest
bTotal N with missing cases
The U.S. Preventive Services Task Force (USPSTF; Siu and Preventive Services Task Force 2016) concluded that there was insufficient evidence to provide a recommendation regarding universal toddler screening for ASD. At the same time they emphasized the potential of the M-CHAT as a universal screening tool, as evidenced by empirical results (R. Canal-Bedia, personal communication, May 9, 2016). Hence, it is necessary to perform a systematic study of the psychometric data available in different studies.
The meta-analysis is an important resource to summarize— in quantitative terms—the accuracy of diagnostic test, providing a higher level of evidence; for this reason, the current study conducted a meta-analysis to review empirical data from the studies and tools used since the first ASD population screening was performed in England (Baron-Cohen et al. 1996).
In this kind of study, the reference test may be imperfect because a gold standard is not available in practice. We have used the Bayesian Hierarchical Model (HSROC; Rutter and Gatsonis 2001) to carry out the meta-analysis. The model is robust in adjusting for the imperfect nature of the reference standard of autism tools, in a bivariate meta-analysis of diagnostic test sensitivity and specificity and others psychometric parameters. Another bivariate model was proposed by Reitsmaet al. ( 2005) in which it is assumed that the vector of (logit(sensitivity), logit(specificity)) follows a bivariate normal distribution. However, Harbord and Whiting ( 2009) showed that the likelihood functions of both the HSROC and bivariate models are algebraically equivalent, and yield identical pooled sensitivity and specificity. Dendukuri et al. ( 2012) have demonstrated the usefulness of HSROC model, when no gold standard test is available.
Therefore, in this study, we used a Bayesian meta-analysis, and the main aim was to evaluate the accuracy of the different screening tools. The second objective was to calculate the pooled psychometric properties associated with different studies to evaluate the tools effectiveness and support their recommendation internationally (R. Canal-Bedia, personal communication, May 9, 2016).
## Methods
The preferred reporting items for systematic reviews and meta-analyses (PRISMA) (Moher et al. 2009) has guided this systematic review.
### Criteria for Selection of Studies
Included papers focused on the screening and diagnosis of ASD and other developmental disorders in the general population, also known as level 1 screening. In cases where studies had duplicated data, only the most complete one was selected in order to avoid an unrealistic increase in the homogeneity between studies, and emphasis was placed on studies validating screening tools, which were often the most complete samples. Therefore, we excluded studies focused on tools that were not designed to screen for ASD, screening studies not applied to the general population (level 1), and all those that did not provide sufficient data to construct a 2 × 2 contingency table of screening × diagnosis (such as those without confirmatory diagnoses), or had a low quality rating in the quality assessment.
### Literature Search
A systematic literature search identified studies that reported tools and procedures used for the early detection of ASD. The articles were obtained from CINHAL, ERIC, PsycINFO, PubMed and WOS databases using several combinations of the relevant keywords and Medical Subject Heading (MeSH), which include the categories of terms suggested by Daniels et al. ( 2014). All articles published between January 1992 and April 2015 were considered eligible. Only articles published in the English language and reporting an age range of screening from 14 to 36 months were included. The search strategy for PubMed is described (see Appendix 1). An additional search was conducted for grey literature captured on other search engines such as Google Scholar; we also searched the reference lists of included articles and any relevant review articles identified through the search and the ‘related articles’ function in PubMed. In addition, when searching the grey literature, we took into account the reference lists of primary studies and review papers, and contacted the experts to locate significant but as yet unpublished studies.
### Assessment of Methodological Quality
Two reviewers conducted quality assessment of the included studies with the QUADAS-2 Tool (Quality Assessment of Diagnostic Accuracy Studies-2) (Whiting et al. 2004). Any discrepancies were referred to a third reviewer. QUADAS is a validated quality checklist (Deeks 2001; Whiting 2011; Whiting et al. 2006) composed of 14 items which encompass the most important sources of bias and variations observed in diagnostic accuracy studies. The studies were classified according to whether they had low or high risk for bias and their applicability was graded as low or high.
### Data Extraction
The following data items were extracted from each study using a data collection form: first author and year of publication; size and characteristics of the study population; raw cell values [true positive ( TP), true negative ( TN), false positive ( FP), false negative ( FN); and psychometric properties, specifically sensitivity ( Se), specificity ( Sp), positive and negative predictive values ( PPV, NPV), positive and negative likelihood ratio values ( LR+; LR−), and diagnostic odds ratio ( DOR)]. See Appendix 2 for definitions of bio-statistical terms. Psychometric properties which were not provided in the studies were calculated based on raw cell values. Clarification was requested from the authors via e-mail when we observed discrepancies between the data reported and the data calculated. Details of the search and results are shown (see Tables 1, 2).
Table 2
Details of individual diagnostic outcomes such as studies show
Study
Se
(95% CI)
Sp
(95% CI)
PPV
(95% CI)
NPV
(95% CI)
LR+
(95% CI)
LR
(95% CI)
Nygren et al. ( 2012)
0.767
(0.614–0.882)
NA
NA
0.917
(0.775–0.982)
NA
NA
NA
NA
NA
NA
Nygren et al. ( 2012)
0.860
(0.721–0.947)
NA
NA
0.925
(0.796–0.984)
NA
NA
NA
NA
NA
NA
Nygren et al. ( 2012)
0.956
(0.849–0.995)
NA
NA
0.896
(0.773–0.965)
NA
NA
NA
NA
NA
NA
Baird et al. ( 2000)
0.213
(0.130–0.300)
0.999
(0.999–1.000)
0.588
(0.420–0.750)
NA
NA
NA
NA
NA
NA
Wiggins et al. ( 2014)
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Wiggins et al. ( 2014)
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Kamio et al. ( 2014)
0.480
(0.330–0.630)
0.990
(0.980–0.990)
0.450
(0.310–0.600)
0.990
(0.980–0.990)
NA
NA
NA
NA
Stenberg et al. ( 2014)
0.341
(0.271–0.417)
0.927
(0.924–0.929)
0.150
(0.120–0.200)
NA
NA
4.60
NA
NA
NA
Chlebowski et al. ( 2013)
NA
NA
NA
NA
0.538
NA
NA
NA
NA
NA
NA
NA
Canal-Bedia et al. ( 2011)
1.000
NA
0.980
(0.980–0.990)
0.190
(0.050–0.330)
1.000
NA
NA
NA
NA
NA
Barbaro and Dissanayake ( 2010)
0.836
(0.776–0.882)
0.998
(0.998–0.999)
0.807
(0.748–0.856)
0.998
(0.998–0.999)
414.39
(303.93–564.99)
0.17
(0.12–0.22)
0.650
NA
0.885
NA
0.088
NA
0.993
NA
NA
NA
NA
NA
0.550
NA
0.961
NA
0.193
NA
0.992
NA
NA
NA
NA
NA
Dereu et al. ( 2010)
0.680
(0.540–0.830)
0.960
(0.960–0.970)
0,100
(0.060–0.130)
1.000
(0.999–1.00)
17.42
NA
0.33
NA
Miller et al. ( 2011)
NA
NA
NA
NA
NA
NA
0.996
NA
NA
NA
NA
NA
Robins et al. ( 2014)
0.854
NA
0.993
NA
0.475
NA
0.999
NA
114.05
NA
0.15
NA
Honda et al. ( 2005)
0.810
NA
NA
NA
NA
NA
0.999
NA
NA
NA
NA
NA
Baranek ( 2015)
0.625
(0.508–0.960)
0.943
NA
0.135
NA
0.994
NA
NA
NA
0.40
NA
Se sensitivity, Sp specificity, PPV positive predictive value, NPV negative predictive value, LR+ positive likelihood ratio, LR− negative likelihood ratio, NA not available from paper
### Data Synthesis and Statistical Analysis
We calculated the pooled Se, Sp, LR+, LR−, PPV, NPV and DOR for the included studies. Separate pooling of sensitivity and specificity may lead to biased results because different thresholds were used in different studies (Deeks 2001; Moses et al. 1993). Therefore, we used the Hierarchical Summary Receiver Operating Characteristic Model (HSROC) (Rutter and Gatsonis 2001) to estimate the diagnostic accuracy parameters and to generate a summary receiver operating characteristic curve with HSROC, [an R package available from CRAN (Schiller and Dendukuri 2015)]. The model is robust for including studies with different reference standards and potential negative correlation in paired measures ( Se/ Sp) across studies (Trikalinos et al. 2012). This kind of analysis models the variation in diagnostic accuracy and cut-off values, and identifies sources of heterogeneity, which is a common feature among diagnostic or screening test accuracy reviews.
The model has been called a “Hierarchical Model” owing to the fact that it takes into account statistical distributions at two levels. At the first level, within-study variability in sensitivity and specificity is examined. At the second level, between-study variability is examined (Macaskill 2004). The main goal of the model is to estimate an SROC curve across different thresholds.
The estimation from the model requires Markov Chain Monte Carlo (MCMC) simulation (Rutter and Gatsonis 2001). To carry out this Bayesian estimation we specified the prior distributions over the set of unknown parameters with a similar assumption made by Higgins et al. ( 2003). This process was used in order to obtain posterior predictions of the Se and Sp. According to Harbord and Whiting ( 2009), the true estimate of Se and Sp in each study could be found by empirical Bayes estimates, although we acknowledge that many of the included studies were limited in their ability to confirm that negative cases were in fact true negatives.
In order to establish whether there was inconsistency and heterogeneity in the meta-analysis, we summarized the test performance characteristics using a forest plot with the corresponding Higgins I 2 index (Higgins and Thompson 2002) and assessed heterogeneity by visual inspection of the SROC plots and using Cochran’s Q test (p > 0.1) (Cochran 1954). Summary DORs were estimated by random DerSimonian–Laird effect model (DerSimonian and Laird 1986) following the recommendations of Macaskill et al. ( 2010) because I 2 was greater than 50% and Q test was < 0.1. Since variability of results among different studies was confirmed, an investigation of heterogeneity was necessary and subgroup analyses were used. The Egger’s test (Song et al. 2002) was calculated for assessing publication bias using STATA 12.0.
Finally, we obtained a crosshair plot and ROC ellipses plot to summarize the confidence intervals of Se and FP cases in each study with the R-package (Doebler 2015) using meta-analysis of diagnostic accuracy (MADA), LR+, LR−, PPV, NPV and DOR were calculated using SAS for Windows, version 9.4 (Cary, NC).
## Results
### Study Selection
The initial literature search identified 1883 studies. Six hundred and sixty-seven duplicate records were eliminated to obtain 1216 non-duplicated articles, 1114 of which were excluded after title and abstract screening through the application of inclusion/exclusion criteria, and 87 were excluded after full text screening or methodological quality assessment and data extraction (see Supplemental Table 1). One additional study that qualified for inclusion was identified from the search of grey literature. Finally, 14 studies: (Baird et al. 2000; Barbaro and Dissanayake 2010; Canal-Bedia et al. 2011; Chlebowski et al. 2013; Dereu et al. 2010; Honda et al. 2005; Inada et al. 2011; Kamio et al. 2014; Miller et al. 2011; Nygren et al. 2012; Robins et al. 2014; Stenberg et al. 2014; Wiggins et al. 2014; Baranek 2015) were eligible for inclusion in our review. We present the flow chart showing the selection process in Fig. 1.
### Methodological Quality of the Included Studies
We used the QUADAS-2 tool for study of quality assessment and K coefficient to examine inter-rater agreement for our initial overall quality score, and resolved any item discrepancies through discussion. The agreement between judges’ kappa values was 0.643 (CI 95%; p < 0.01). In Fig. 2, we summarize the results of the methodological quality for all 20 studies included in this assessment: (Baird 2000; Barbaro 2010; Canal-Bedia et al. 2011; Chlebowski 2013; Dereu 2010; Dietz 2006; Honda 2005, 2009; Inada 2011; Kamio 2014; Kleinman 2008; Miller 2011; Nygren et al. 2012; Pierce 2011; Robins 2008, 2014; Stenberg 2014; VanDenHeuvel 2007; Wetherby 2008; Wiggins et al. 2014).
As Fig. 2 shows, two bar graphs report the assessment of risk of bias and applicability. The percentage of studies rated as unclear, high, or low is observed across X-axes at intervals of 20%. The concerns regarding applicability include three domains: patient selection, index test, and reference standard. The risk of bias dimension is comprised of four domains: patient selection, index test, reference standard, and flow and timing. Across a majority of studies, concern about applicability of the reference standard was assessed as low, the index test was assessed as unclear, and patient selection was assessed as having low concerns. Regarding risk or bias, the majority of the studies demonstrated high risk of bias for flow and timing; the index test was rated as unclear risk, the reference standard was generally rated as low risk, and patient selection was rated as low risk.
During this process we excluded the following studies: Honda ( 2009), Pierce ( 2011), Robins ( 2008), VanDeHeuvel ( 2007), Wetherby ( 2008). In supplemental materials (see supplemental Table 1) we show the list of papers excluded during analysis of quality and data extraction processes.
### Characteristics of the Included Studies
One hundred and two full text articles were assessed for eligibility, 14 (13.72%) of which were included in the quantitative synthesis. Some articles evaluated more than one index test (Inada et al. 2011; Nygren et al. 2012; Wiggins et al. 2014) and this is why we present a meta-analysis on 18 sets of psychometric values, 35.71% of which came from the USA, 35.71% from Europe, 21.42% from Japan and 7.14% from Australia. The sample includes 191,803 toddlers. The interval of age range is between 16.7 and 29 months. Sex data was available for 158,965 toddlers, of whom 73,431 (46.19%) were female.
The studies presented great variability in terms of the data reported. Twelve of 14 studies (66.6%) showed all the primary outcomes required to populate 2 × 2 contingency tables. Data pertaining to Se were presented in 77.7% of studies, Sp in 55.5%, PPV in 77.7%, NPV in 44.4%, and LR+ and LR− in 22.2% of studies. The main characteristics and the clinical outcomes, as shown in included studies are presented (see Tables 1, 2).
### Diagnostic Accuracy of Screening Tools
The accuracy of screening tools was evaluated in 14 studies that assessed the test characteristics of various screening tools (18 in all). The pooled Se was 0.72 (95% CI 0.61–0.81) and the Sp was 0.98 (95% CI 0.97–0.99). The positive likelihood ratio (LR+) was 131.27 (95% CI 50.40–344.48) and the negative likelihood ratio (LR−) was 0.22 (95% CI 0.13–0.45). The diagnostic odds ratio (DOR) was 596.09 (95% CI 174.32–2038.34). The positive predictive value (PPV) was 97.78 (95% CI 97.71–97.84) and the negative predictive value (NPV) was 93.13 (95% CI 93.02–93.24). The above is summarized in Table 3, while the corresponding HSROC plot is presented in Fig. 3. The Se of each individual study varied between 0.22 and 0.95 whereas the Sp ranged from 0.81 to 0.99 (see Table 4).
Table 3
Parameters estimated between studies (point estimate = median) both for the entire meta-analysis and for the sub-analysis of nine studies
Parameters
Meta-analysis with all studies selected (N = 18)
Meta-analysis: subgroup of analysis (N = 9)
Estimated
SD
MC_error
C.I._lower
C.I._upper
Estimated
SD
MC_error
C.I._lower
C.I._upper
HSROC THETA a
0.86
0.13
< 0.01
0.12
0.60
0.51
0.16
0.01
0.16
0.17
HSROC LAMBDA b
2.89
0.13
< 0.01
2.59
2.99
2.90
0.14
< 0.01
2.56
2.99
HSROC Beta c
− 0.09
< 0.01
< 0.01
− 0.09
− 0.09
0.38
0.09
0.01
0.20
0.55
σ α d
1.09
0.21
< 0.01
0.74
1.57
1.07
0.31
0.01
0.59
1.77
σ θ e
0.51
0.10
< 0.01
0.35
0.75
0.32
0.13
< 0.01
0.14
0.60
Se overall
0.72
0.05
< 0.01
0.61
0.81
0.77
0.03
< 0.01
0.69
0.84
Sp overall
0.98
< 0.01
< 0.01
0.97
0.99
0.99
< 0.01
< 0.01
0.97
0.99
MC error of each parameter smaller than 10% of its posterior standard deviation
Se sensitivity, Sp specificity
aTHETA = the overall mean cut-off value for defining a positive test
bLAMBDA = the overall diagnostic accuracy
cBeta = the logarithm of the ratio of the standard deviation of test results among patients with the disease and among patients without the disease
dσ α = the between-study standard deviation of the difference in means
eσ θ = the between-study standard deviation in the cut-off
Table 4
Estimates of diagnostic precision and outcomes in single studies
Study
Screening test
THETA a (95% CI)
ALPHA b (95% CI)
Prevalence c (95% CI)
Sensitivity ( Se) (95% CI)
Specificity ( Sp) (95% CI)
Estimated
SD
Estimated
SD
Estimated
SD
Estimated
SD
Estimated
SD
Nygren et al. ( 2012)
M-CHAT
1.31 (1.06–1.56)
0.12
3.95 (3.45–4.46)
0.24
0.01 (< 0.01–0.01)
< 0.01
0.75 (0.63–0.87)
0.06
0.99 (0.99–1)
< 0.01
Nygren et al. ( 2012)
JOBS
1.16 (0.89–1.41)
0.13
4.21 (3.72–4.72)
0.25
0.01 (< 0.01–0.01)
< 0.01
0.84 (0.72–0.93)
0.05
0.99 (0.99–1)
< 0.01
Nygren et al. ( 2012)
M-CHAT + JOBS
0.86 (0.58–1.12)
0.13
4.52 (4.02–5.03)
0.25
0.01 (< 0.01–0.01)
< 0.01
0.92 (0.85–0.98)
0.03
0.99 (0.99–1)
< 0.01
Baird et al. ( 2000)
CHAT
1.99 (1.84–2.15)
0.07
2.58 (2.27–2.86)
0.15
< 0.01 (< 0.01 to < 0.01)
< 0.01
0.22 (0.15–0.31)
0.04
0.99 (0.99–1)
< 0.01
Wigginset al. ( 2014)
M-CHAT
0.81 (0.53–1.05)
0.13
3.86 (3.37–4.40)
0.26
< 0.01 (< 0.01–0.01)
< 0.01
0.88 (0.77–0.96)
0.05
0.99 (0.99–1)
< 0.01
Wigginset al. ( 2014)
PEDS + PATH
0.65 (0.39–0.94)
0.13
3.88 (3.33–4.44)
0.28
0.01 (< 0.01–0.01)
< 0.01
0.91 (0.80–0.97)
0.04
0.99 (0.99–1)
< 0.01
Kamio et al. ( 2014)
M-CHAT_JV
1.15 (0.98–1.35)
0.09
2.28 (1.89–2.64)
0.19
0.02 (0.01–0.03)
< 0.01
0.49 (0.35–0.62)
0.07
0.98 (0.98–0.99)
< 0.01
Stenberg et al. ( 2014)
M-CHAT
− 0.05 (− 0.14–0.01)
0.05
3.13 (2.97–3.31)
0.09
< 0.01 (< 0.01 to < 0.01)
< 0.01
0.95 (0.93–0.97)
< 0.01
0.92 (0.92–0.93)
< 0.01
Chlebowski et al. ( 2013)
M-CHAT /YALE SCREENER and STAT
0.76 (0.59–0.91)
0.08
3.98 (3.68–4.30)
0.15
< 0.01 (< 0.01 to < 0.01)
< 0.01
0.90 (0.84–0.95)
0.02
0.99 (0.99–1)
< 0.01
Canal-Bedia et al. ( 2011)
M-CHAT
0.54 (− 0.01 to − 1.03)
0.26
3.63 (2.63–4.69)
0.52
< 0.01 (< 0.01 to < 0.01)
< 0.01
0.90 (0.68–0.99)
0.09
0.98 (0.98–0.99)
< 0.01
Barbaro and Dissanayake ( 2010)
SACS
1.06 (0.96–1.16)
0.05
3.90 (3.70–4.10)
0.10
0.01 (< 0.01–0.01)
< 0.01
0.82 (0.77–0.87)
0.02
0.99 (0.99–1)
< 0.01
M-CHAT (short version 9, cutoff:1)
0.23 (< 0.01–0.43)
0.10
1.44 (1.02–1.85)
0.20
0.02 (0.01–0.03)
< 0.01
0.69 (0.54–0.83)
0.07
0.81 (0.79–0.84)
0.01
M-CHAT (full version)
0.66 (0. 47–0.84)
0.09
1.71 (1.31–2.07)
0.19
0.03 (0.02–0.04)
< 0.01
0.58 (0.43–0.72)
0.07
0.92 (0.91–0.94)
< 0.01
Dereu et al. ( 2010)
CESDD
0.68 (0.56–0.83)
0.07
2.32 (2.02–2.59)
0.15
< 0.01 (< 0.01 to <0.01)
< 0.01
0.69 (0.58–0.77)
0.05
0.96 (0.95–0.96)
< 0.01
Miller et al. ( 2011)
ITC + M-CHAT
0.61 (0.27–0.93)
0.17
2.89 (2.23–3.61)
0.34
0.01 (0.01–0.03)
< 0.01
0.81 (0.62–0.96)
0.08
0.97 (0.96–0.98)
< 0.01
Robins et al. ( 2014)
M-CHAT-R/F
0.78 (0.67–0.91)
0.06
3.53 (3.27–3.79)
0.13
< 0.01 (< 0.01 to < 0.01)
< 0.01
0.84 (0.78–0.90)
0.03
0.99 (0.99–1)
< 0.01
Honda et al. ( 2005)
YACHT-18
1.58 (1.41–1.75)
0.08
4.27 (4.00–4.56)
0.14
< 0.01 (< 0.01–<0.01)
< 0.01
0.71 (0.63–0.79)
0.04
0.99 (0.99–1)
< 0.01
Baranek ( 2015)
M-CHAT
0.68 (0.31–1.33)
0.18
1.99 (1.27–2.71)
0.37
0.01 (< 0.01–0.01)
< 0.01
0.62 (0.35–0.85)
0.13
0.94 (0.92–0.96)
< 0.01
Se sensitivity, Sp specificity
aTHETA = the overall mean cut-off value for defining a positive test
bALPHA = the ‘accuracy parameter’ measures the difference between TP and FP within-study parameters
cPrevalence within-study parameters
### Exploration of Heterogeneity
A considerable degree of heterogeneity in sensitivities was observed (Q = 337.62, df = 17.00, p < 0.001) and specificities (Q = 30901.50, df = 17.00, p < 0.001). The heterogeneity in test accuracy between studies may be due to differences in cut-offs utilized in different studies, among other factors (Doebler et al. 2012). To delve deeper into the understanding of these results, we evaluated the confidence intervals which describe the relationship between the psychometric properties. The ROC ellipse plots of the confidence intervals in Fig. 3 shows the studies responsible for high levels of heterogeneity, how cut-off values vary, and how they demonstrate moderate negative correlations between sensitivities and False Positive rates ( r s = − 0.355), that is, if Se tends to decrease when FP rate increases.
According to this analysis, study 18 (Baranek 2015), study 14 (Dereu et al. 2010), studies 12 and 13 (Inada et al. 2011) and study 15 (Miller et al. 2011) show the largest confidence intervals both for Se and FP rate, and study 4 (Baird et al. 2000), study 10 (Canal-Bedia et al. 2011), study 7 (Kamio et al. 2014) and study 8 (Stenberg et al. 2014) indicate large confidence intervals only in Se.
The SROC curve summarizes the relationship between Se and (1 − Sp) across studies, taking into account the between-study heterogeneity. We constructed a SROC curve using all studies selected; see Fig. 3. It is worth noting that it is a significant graphical tool for understanding how the diagnostic accuracy of the different test depends on the different cut-off (Doebler et al. 2012).
As Fig. 4 shows, the prediction region covers a larger range of Se than Sp. This may be due to the fact that most of the studies had a considerably larger number of participants with screen negative results compared to screen positive results, leading to greater sampling variability when we estimated Se vs. Sp. The figure also demonstrates an asymmetry of the test performance measures towards a higher Sp with higher variability of Se, providing indirect proof of some threshold variability. The figure also shows how when the threshold is increased then Se is decreased but Sp is increased.
The posterior predictive value of Se was 0.71 (95% CI 0.22–1) with a standard error of 0.23 and that of Sp was 0.98 (95% CI 0.81–1) with a standard error of 0.07.
### Subgroup of Analysis
A large degree of heterogeneity was observed. Heterogeneity may be due to different factors (Macaskill et al. 2010; Trikalinos et al. 2012). In order to investigate the source of heterogeneity in the current sample, we followed recommendations of these authors and conducted analyses using a subgroup of studies. The new meta-analysis excluded the following studies, based on graphical analysis and the Cochran Q test (p > 0.1): Study 4 (Baird et al. 2000), Study 7 (Kamio et al. 2014), Study 8 (Stenberg et al. 2014), Study 10 (Canal-Bedia et al. 2011), Studies 12 and 13 (Inada et al. 2011), Study 14 (Dereu et al. 2010), Study 15 (Miller et al. 2011), and Study 18 (Baranek 2015).
Regarding the estimations between study parameters, subgroup analysis demonstrated that Se was increased because the pooled sensitivity was 0.77 (95% CI 0.69–0.84), and the Sp was 0.99 (95% CI 0.97–0.99). The posterior predictive p-value of Se was 0.81 (95% CI 0.39–1) and Sp, 0.97 (95% CI 0.76–1, SD = 0.08).
Parameters estimated between studies by HSROC model are shown in Table 3, which demonstrates how the parameters estimated for the subgroup of analysis are higher results than those obtained for the first meta-analysis. For example, it is of note that standard deviation in the cut-off and standard deviation of the difference in means between studies are decreased.
The estimates for individual studies were grouped by parameters and are shown in Table 5.
Table 5
Estimates of diagnostic precision and outcomes in single studies for the sub-analysis of nine studies
Study
Screening test
THETA a (95% CI)
ALPHA b (95% CI)
Prevalence c (95% CI)
Se (95% CI)
Sp (95% CI)
Estimated
SD
Estimated
SD
Estimated
SD
Estimated
SD
Estimated
SD
Nygren et al. ( 2012)
M-CHAT
0.82 (0.47–1.14)
0.17
3.56 (3.45–4.46)
0.29
0.01 (< 0.01–0.01)
< 0.01
0.78 (0.65–0.90)
0.06
0.99 (0.99–1)
< 0.01
Nygren et al. ( 2012)
JOBS
0.65 (0.31–0.98)
0.17
3.93 (3.72–4.72)
0.28
0.01 (< 0.01 -01)
< 0.01
0.86 (0.76–0.94)
0.05
0.99 (0.99–1)
< 0.01
Nygren et al. ( 2012)
M-CHAT + JOBS
0.34 (-0.03–0.71)
0.19
4.32 (4.02–5.03)
0.33
0.01 (< 0.01–0.01)
< 0.01
0.93 (0.85–0.98)
0.03
0.99 (0.99–1)
< 0.01
Wiggins et al. ( 2014)
M-CHAT
0.35 (− 0.06 to 0.76)
0.20
3.61 (3.37–4.40)
0.33
< 0.01 (< 0.01–0.01)
< 0.01
0.88 (0.76–0.96)
0.05
0.99 (0.99–1)
< 0.01
Wiggins et al. ( 2014)
PEDS + PATH
0.24 (− 0.15 to 0.76)
0.20
3.57 (3.33–4.44)
0.36
0.01 (< 0.01–0.01)
< 0.01
0.89 (0.77–0.98)
0.04
0.99 (0.99–1)
< 0.01
Chlebowski et al. ( 2013)
M-CHAT /YALE SCREENER/STAT
0.24 (0.04–0.42)
0.10
3.87 (3.68–4.30)
0.21
< 0.01 (< 0.01 to < 0.01)
< 0.01
0.91 (0.85–0.95)
0.02
0.99 (0.99–1)
< 0.01
Barbaro and Dissanayake ( 2010)
SACS
0.60 (0.36–0.81)
0.10
3.56 (3.70–4.10)
0.14
0.01 (< 0.01 to < 0.01)
< 0.01
0.83 (0.78–0.88)
0.02
0.99 (0.99–1)
< 0.01
Robins et al. ( 2014)
M-CHAT-R/F
0.36 (0.14–0.49)
0.08
3.26 (3.27–3.79)
0.15
< 0.01 (< 0.01 to <0.01)
< 0.01
0.85 (0.80–0.91)
0.03
0.99 (0.99–1)
< 0.01
Honda et al. ( 2005)
YACHT-18
0.98 (0.66–1.29)
0.16
4.15 (4.00–4.56)
0.20
< 0.01 (< 0.01 to <0.01)
< 0.01
0.81 (0.73–0.89)
0.04
0.99 (0.99–1)
< 0.01
MC error of each parameter smaller than 10% of its posterior standard deviation
Se sensitivity, Sp specificity
aTHETA = the overall mean cut-off value for defining a positive test
bALPHA = the ‘accuracy parameter’ measures the difference between TP and FP within-study parameters
cPrevalence within-study parameters
Figure 5 shows how the prediction region covers a larger range of Se than Sp although this is less than in the first meta-analysis. The figure also shows less asymmetry of the test performance and therefore less heterogeneity. This means that the range, which includes the measurements for Se and Sp is lower than the one shown in Fig. 4.
### Publication Bias
The estimated Egger bias coefficient was 3.21 (95% CI − 0.49 to 6.92) with a standard error of 1.5, giving a p-value of 0.08. The test thus suggests evidence that results are not biased by the presence of small-study effects.
## Discussion
Interest in early detection of ASD is increasing, due to the growing evidence that early intervention improves prognosis. Low-risk screening, as part of pediatric primary care, for example, is one of the most widely studied strategies to promote early detection.
Consequently, the information reported from systematic reviews of screening accuracy is valuable, both for research and practice. Different systematic reviews, such as the ones carried out by Daniels et al. ( 2014) and McPheeters et al. ( 2016), have represented an important advance with regard to traditional or narrative reviews, which were characterized by a lack of systematization. However, a meta-analysis is a systematic review which also uses statistical methods to analyze the results of the included studies. It is accepted that data from systematic reviews with meta-analyses adds value since the statistical analysis used converts the results of primary studies into a measure of integrated quantitative evidence. This is beneficial both to the scientific community and to the clinicians who use the tools in such meta-analyses.
Meta-analysis of screening studies is a complex but critical approach to examining evidence across measures and scoring thresholds in different populations (Gatsonis and Paliwal 2006). We employed a Bayesian Hierarchical Model (Rutter and Gatsonis 2001), which is robust in adjusting for the imperfect nature of the reference standard of autism tools, in a bivariate meta-analysis of diagnostic test sensitivity and specificity and others psychometric parameters. This kind of meta-analysis statistically compares the accuracy of different diagnostic screening tests and describes how test accuracy varies. Therefore, it is more likely to lead to a ‘gold standard’ than other types of reviews which can be influenced by biases associated with the publication of single studies.
The HSROC model was used to estimate the screening accuracy parameters and a summary in each study as functions of an underlying bivariate normal model. This model has been recommended when there is no standard cut-off to define a positive result (Bronsvoort et al. 2010; Dukic and Gatsonis 2003; Macaskill 2004) in order to allow the meta-analytic assessment of heterogeneity between studies while taking into consideration both within- and between-study variability. Furthermore, it is also optimally suited when more information is available, for example, when the studies have reported results from more than one modality (Rutter and Gatsonis 2001) like our case. The advantages of the model have been discussed (Gatsonis and Paliwal 2006; Leeflang et al. 2013; Macaskill 2004; Rutter and Gatsonis 2001) and support its selection in this meta-analysis.
This review included 14 studies that assessed the test characteristics of various screening tools (18 in all) for detecting autism and a subgroup of analysis retaining nine studies that demonstrated lower heterogeneity. Initial findings of the overall meta-analysis show that tools which are used in level 1 ASD screening are accurate at detecting the presence of ASD [pooled sensitivity was 0.72 (95% CI 0.61–0.81)] and highly accurate at detecting a lack of presence of ASD [pooled of specificity was 0.98 (95% CI 0.97–0.99)]. But more importantly, we demonstrate the tools’ performance in identifying autism, DOR 596.09 (95% CI 174.32–2038.34). The clinical utility of the level 1 screening tools reviewed in this study is clear because the pooled positive likelihood ratio (LR+) was 131.27 (95% CI 50.40–344.48) and the negative likelihood ratio (LR−) was 0.22 (95% CI 0.13–0.45). LR+ > 1 indicates the results are associated with the disease. Although those findings are informative to clinicians, it is important to understand the limitations of the last assertion because the accuracy of a LR depends upon the quality of the studies that generated the pooled of sensitivity and specificity, therefore data must be interpreted with caution. Finally, the pooled of positive predictive value (PPV) was 97.78 (95% CI 97.71–97.84) and the negative predictive value (NPV) was 93.13 (95% CI 93.02–93.24).
A limitation of this meta-analysis comes from the methodological limitations of the included studies; 55% of the included studies were assessed to have high risk or unclear risk of bias in the quality analysis with QUADAS, particularly in the domains of flow and timing, and in the index test. We recommend that future screening studies include a flowchart with information about the method of recruitment of patients, sample, order of test execution, follow up and other details related to the process to improve replicability and to better inform readers about potential bias.
The second concern is about the heterogeneity of the psychometric data in the included studies. In this respect, according to Doebler et al. ( 2012), in diagnostic meta-analysis the observed sensitivities and specificities can vary across primary studies and heterogeneity should be assumed in results of this kind of meta-analysis (Macaskill et al. 2010). This assertion has been acknowledged in this work and justifies the choice of the model HSROC, which is a more robust model for addressing heterogeneity compared to some of the other meta-analysis models.
Following the recommendations of Macaskill et al. ( 2010) and Trikalinos et al. ( 2012) we conducted a subgroup of analyses to assess the pooled Se and Sp without those studies driving heterogeneity in analyses. The pooled of sensitivity and specificity were improved by the exclusion of these studies. Consequently, the parameters estimated for this set of studies suggested a good performance for ruling out and ruling in ASD since the prior pooled Se was 0.77 (95% CI 0.69–0.84, SD = 0.03), Sp was 0.99 (95% CI 0.97–0.99; SD ≤ 0.01), the posterior predictive p-value of Se was 0.81 (95% CI 0.39–1, SD = 0.18), and high specificity was maintained, 0.97 (95% CI 0.76–1, SD = 0.08). The previous data from the posterior predictive p-values of Se and Sp are very important because the true estimate of Se and Sp in each study could be found by empirical Bayes estimates (Harbord and Whiting 2009).
One important aspect to bear in mind is that only about 66.6% of all studies showed all the primary outcomes required to populate 2 × 2 contingency tables. Data pertaining to the Se were presented in 77.7% of studies, Sp in 55.5%, PPV in 77.7%, NPV in 44.4%, LR+ and LR− in 22.2% of studies. This leads us to recommend that authors of screening studies include sufficient detail to calculate all psychometric properties to improve the quality of systematic reviews and future meta-analyses. It also would be valuable for authors of future studies to reflect on the question of why there is such a low percentage of primary studies that do provide those data. Some authors use caution in presenting psychometric properties when the negative cases cannot be confirmed to be true negatives. Although this is a notable limitation of cross-sectional screening studies, given that confirmatory evaluations are prohibitive in very large samples, it is likely that the number of truly negative cases greatly outnumbers those cases that will later be identified as false negatives, suggesting that interpreting the TN cell of the 2 × 2 matrix to be “presumed TN” is a reasonable assertion. Looking further at the omission of specific psychometric values, there is a remarkably low percentage of studies that include LR+ and LR−, as well as a number that do not report NPV. LR+ and LR− may not have been commonly included given that they were not emphasized in the American Academy of Pediatrics’ policy statement that highlighted the psychometric properties of Se and Sp. The reduced emphasis on NPV may be due to the fact that predictive value is affected by baserate of the disorder in the sample being studied (such as PPV and NPV may vary dramatically across sampling strategies), whereas Se and Sp are not influenced by base rate. We recommend that future studies report comprehensive psychometrics, in order to promote understanding of the findings. In addition, it is often difficult to ascertain characteristics of the study, study cohort, and technical aspects (Gatsonis and Paliwal 2006). In future studies, a unified approach is necessary in presenting results of screening research to avoid the inconsistency and heterogeneity observed.
The present results suggested improved screening accuracy when meta-analysis was restricted to a subset of studies with reduced heterogeneity (see Table 3 for a comparison of parameters for the complete meta-analysis and the subgroup meta-analysis). The subgroup findings add specific knowledge for clinicians and researchers regarding each tool used for toddler ASD screening.
We have estimated parameters for each study in both meta-analyses (see Tables 4, 5). The results from subgroup analysis suggest that the Se of each individual study varied between 0.78 and 0.88. In those tables we also reported other important data, which could be a particular contribution for the clinicians in this field of study, such as the different cut-off points or the ‘accuracy parameter’, which measures the difference between TP and FP in each study and the prevalence. With respect to prevalence, we can say that it was estimated at or near 1% depending on the studies.
Finally, in the light of the results obtained by computing the summary measures with and without studies (shown as outliers Tables 3, 4, 5) we suggest that the tools used in Level 1 screening are adequate to detect ASD in the 14–36 age range. Thus, we confirm - in quantitative terms- the finding of the USPSTF that screening detects ASD.
## Conclusion
A systemic review and meta-analysis of screening tools to detect ASD in toddlers determined that these measures detect ASD with high Se and Sp. Studies were restricted to low-risk samples in children younger than 3 years old, in order to evaluate the use of these screening tools in primary pediatric care. Given that children who start ASD-specific early intervention before age three have improved outcomes compared to children who go untreated prior to preschool, it is essential to disseminate strategies to improve the identification of the children in need of intervention as young as possible. Consistent with the recommendation of the American Academy of Pediatrics (Johnson et al. 2007) results of the current study show the validity of low-risk screening to identify ASD in children under 3 years old.
## Acknowledgments
The authors thank their colleagues from the AJ Drexel Autism Institute and others that have supported this research. Special thanks to Dr. Newschaffer, to members of Dr. Robins’ team, and especially at UNC Chapel Hill to Dr. Baranek who contributed as yet unpublished data to this meta-analysis. We likewise wish to thank all the researchers whom we contacted during the search for grey literature. Also, the authors express special appreciation to Dr. Canal-Bedía, Magán-Maganto and de Pablos who took part in the process of qualitative review and to Dr. Verdugo-Alonso for providing ongoing support for this project. Finally, we thank the Fulbright Commission for supporting this Project.
## Compliance with Ethical Standards
### Ethical Approval
The information and analysis in this research is essentially based on data gathered on previous primary studies in which ethical approval.
### Informed Consent
Informed consent were obtained by the investigators from all individual participants included in their studies.
## Appendix 1
### The Search Strategy Described on PubMed was Carried on May 2015
#1 “Autistic Disorder” [Majr] OR “Autistic Disorder” [Title/Abstract] OR “Autistic Disorders” [Title/Abstract] OR “Autism” [Title/Abstract] OR “Child Development Disorders, Pervasive” [Majr] OR “Pervasive Developmental Disorder” [Title/Abstract] OR “Pervasive Developmental Disorders” [Title/Abstract] OR “PDD” [Title/Abstract] OR “Autistic Spectrum Disorder” [Title/Abstract] OR “Autistic Spectrum Disorders” [Title/Abstract] OR “Autism Spectrum Disorder” [Title/Abstract] OR “Autism Spectrum Disorders” [Title/Abstract] OR “ASD” [Title/Abstract]
#2 “Diagnosis” [Mesh:noexp] OR “Diagnosis” [Subheading] OR “Diagnosis” [Title/Abstract] OR “Early Diagnosis” [Mesh:noexp] OR “Early Diagnosis” [Title/Abstract] OR “Detection” [Title/Abstract] OR “Early Detection” [Title/Abstract] OR “Early Identification” [Title/Abstract] OR “Early Intervention” [Title/Abstract] OR “Early Prediction” [Title/Abstract]
#3 “Screening” [Title/Abstract] OR “Early Screening” [Title/Abstract] OR “Mass Screening” [Majr:noexp] OR “Mass Screening/instrumentation” [Majr:noexp] OR “Mass Screening/methods” [Majr:noexp] OR “Mass Screening” [Title/Abstract] OR “Screening Tool” [Title/Abstract] OR “Screening Tools” [Title/Abstract] OR “Screening Test” [Title/Abstract] OR “Screening Instrument” [Title/Abstract] OR “Screening Instruments” [Title/Abstract] OR “Checklist” [MeSH Terms] OR “Checklist” [Title/Abstract] OR “Checklists” [Title/Abstract] OR “Follow-up” [Title/Abstract]
#4 (#2 AND #3)
#5 (#1 AND #4)
#6 “Infant” [MeSH Terms:noexp] OR “Child, Preschool” [MeSH Terms] OR “Infant” [Title/Abstract] OR “Infants” [Title/Abstract] OR “Preschool Child” [Title/Abstract] OR “Preschool Children” [Title/Abstract] OR “Toddler” [Title/Abstract] OR “Toddlers” [Title/Abstract]
#7 (#5 AND #6)
#8 “1992/01/01” [PDAT]: “2015/04/31” [PDAT]
#9 English[Lang]
#10 (#7 AND #8 AND #9)
## Appendix 2
### Definitions for Bio-Statistical Terms that may not be Familiar to Readers
Cochran Q Statistic for Heterogeneity is used to determine whether variations between primary studies represent true differences or are due to chance. A p value < 0.05 indicates the presence of heterogeneity due to the low statistical strength of Cochran’s Q test.
$$Q=\mathop \sum \nolimits^{} {w_i}{\left( {{T_i} - \bar {T}} \right)^2}$$
Diagnostic accuracy relates to the ability of a test to discriminate between the target condition and health. This discriminative ability can be quantified by the measures of diagnostic accuracy: sensitivity and specificity/positive and negative predicative values (PPV, NPV)/likelihood ratio/the area under the ROC curve (AUC)/diagnostic odds ratio (DOR).
Diagnostic Odds Ratio measures of the effectiveness of a diagnostic test:
$$DOR=(LR+)/(LR- )=(TP/FN)/(FP/TN).$$
Eggers test is a simple linear regression of the magnitude of the effect divided by the standard error over the inverse standard error which verifies whether the Y intercept is statistically significant with p < 0.1.
Graphical analysis the starting point for investigation of heterogeneity in diagnostic or screening accuracy reviews often is through visual assessment of study results in forest plots and in ROC space.
Grey literature is generally understood to mean literature that is not formally published in accessible sources. It can be another source of bias in meta-analytical studies.
I 2 Measure for Heterogeneity indicates the percentage of variance in a meta-analysis that is attributable to studies heterogeneity. I 2 values range from 0 to 100%. I 2 values of 25%, 50%, and 75% are interpreted as low, moderate, and high estimates, respectively:
$${I^2}=\left\{ {\begin{array}{*{20}{c}} {\frac{{Q - \left( {k - 1} \right)}}{1} \times \,100\% }&{to\;Q>k - 1} \\ 0&{to\;Q \leqslant k - 1} \end{array}} \right.$$
Negative Likelihood Ratio ( LR−) shows how much the odd of the target condition is decreased when the test index is negative.
$$LR- =(1 - Se)/Sp$$
Negative Predictive Value (NPV) probability of no target condition among patients with a negative index test result.
$$NPV=(TN)/(TN+FN)$$
Positive Predictive Value (PPV) probability of target condition among patients who actually have the disease.
$$PPV=TP/(TP+FP)$$
Positive Likelihood Ratio ( LR+) shows how much the odds of the target condition are increased when the test index is positive.
$$LR+=Se/(1 - Sp)$$
Publication bias is the term for what occurs whenever the research that appears in the published literature is systematically unrepresentative of the population of completed studies.
The posterior predictive p-value is a Bayesian alternative to the classical p-value. It is used to calculate the tail-area probability corresponding to the observed value of the statistic.
p-value The probability under the assumption of null hypothesis, of obtaining a result equal to or more extreme than what was observed. It shows whether a difference found between groups that are being compared is due to chance.
Sensitivity (Se) proportion of positives patients with the target condition who are identified as having the condition.
$$Se=(TP)/(TP+FN)$$
Specificity (Sp) proportion of negatives patients without the target condition who are identified as not having the condition.
$$Sp=(TN)/(TN+FP)$$
## Electronic supplementary material
Below is the link to the electronic supplementary material.
## Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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Naar de uitgave | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8198122978210449, "perplexity": 4432.664391709809}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-05/segments/1642320299852.23/warc/CC-MAIN-20220116093137-20220116123137-00122.warc.gz"} |
https://pyvisa.readthedocs.io/en/stable/example.html | # A more complex example¶
The following example shows how to use SCPI commands with a Keithley 2000 multimeter in order to measure 10 voltages. After having read them, the program calculates the average voltage and prints it on the screen.
I’ll explain the program step-by-step. First, we have to initialise the instrument:
>>> keithley = rm.open_resource("GPIB::12")
>>> keithley.write("*rst; status:preset; *cls")
Here, we create the instrument variable keithley, which is used for all further operations on the instrument. Immediately after it, we send the initialisation and reset message to the instrument.
The next step is to write all the measurement parameters, in particular the interval time (500ms) and the number of readings (10) to the instrument. I won’t explain it in detail. Have a look at an SCPI and/or Keithley 2000 manual.
>>> interval_in_ms = 500
>>> keithley.write("status:measurement:enable 512; *sre 1")
>>> keithley.write("trigger:source bus")
>>> keithley.write("trigger:delay %f" % (interval_in_ms / 1000.0))
>>> keithley.write("trace:feed sense1; feed:control next")
Okay, now the instrument is prepared to do the measurement. The next three lines make the instrument waiting for a trigger pulse, trigger it, and wait until it sends a “service request”:
>>> keithley.write("initiate")
>>> keithley.assert_trigger()
>>> keithley.wait_for_srq()
With sending the service request, the instrument tells us that the measurement has been finished and that the results are ready for transmission. We could read them with keithley.query(“trace:data?”) however, then we’d get:
-000.0004E+0,-000.0005E+0,-000.0004E+0,-000.0007E+0,
-000.0000E+0,-000.0007E+0,-000.0008E+0,-000.0004E+0,
-000.0002E+0,-000.0005E+0
which we would have to convert to a Python list of numbers. Fortunately, the query_ascii_values() method does this work for us:
>>> voltages = keithley.query_ascii_values("trace:data?")
>>> print("Average voltage: ", sum(voltages) / len(voltages))
Finally, we should reset the instrument’s data buffer and SRQ status register, so that it’s ready for a new run. Again, this is explained in detail in the instrument’s manual:
>>> keithley.query("status:measurement?")
>>> keithley.write("trace:clear; feed:control next")
That’s it. 18 lines of lucid code. (Well, SCPI is awkward, but that’s another story.) | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.42911428213119507, "perplexity": 4399.555479060749}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-09/segments/1550247481428.19/warc/CC-MAIN-20190217010854-20190217032854-00058.warc.gz"} |
https://mpasa.me/articles/top-elements-by-key-apache-spark | I'm a computer scientist from Barcelona. I'm passionate about FP (mostly Scala), data, algorithms and mountains.
# Top elements by key in Apache Spark
## The problem
Imagine we are responsible of managing a global music streaming service. We have tons of users playing their favourite tunes every day. Each song play is logged by our system, along with the song's metadata and information of the user playing it. We model this domain using 3 simple case classes:
final case class Song(artist: String, title: String)
final case class User(username: String, city: String)
final case class SongPlay(song: Song, user: User)
We are able to read the data from our data lake to get a RDD[SongPlay] with all the song plays. We will be using the Spark's RDD API, but we could replicate it using the Dataset API in a very similar way.
Imagine now that we want to improve our ads performance segmenting them by city. A thing we can do is calculate the top songs by city and generate a customized ad for each one. That is, we want to transform our RDD[SongPlay] into a RDD[(String, Seq[(Song, Int)])], with the top songs for each city and their number of plays. Let's get on with it.
## Natural and naïve approach
The first approach that comes to our mind when we get into the problem is straightforward:
def topSongsByCity(songPlays: RDD[SongPlay], numTop: Int) = {
songPlays.groupBy(_.user.city).map {
case (city, songPlaysCity) =>
city -> songPlaysCity
.groupBy(_.song)
.mapValues(_.toSeq.length)
.toSeq
.sortBy(-_._2)
.take(numTop)
}
}
1. We want to calculate the top songs in a city, so we group the plays by city. This transforms our RDD[SongPlay] into a RDD[(String, Iterator[SongPlay])], where they key is the name of city.
2. For each city, we group the plays by song. We are now working with a Map[Song, Iterator[SongPlay]].
3. For each song, we can get the number of plays using the length method of the sequence of song plays.
4. Then, we sort the result by the number of plays in descending order.
5. Finally, we just get the first numTop elements of the sorted sequence.
## Problems of the naïve approach
Our first approach works just fine in the tests. When we deploy it to production, though, our face quickly changes from happiness to sadness as it starts to fail. We are getting random OOM errors for a few tasks. What is happening?
Grouping data is a natural way of solving problems, but it normally does a lot of work that is not necessary. Firstly, groupBy performs a full shuffle of our data. This means that every song play will be send over the network. Ask yourself what is the total size of the dataset and what's the bandwidth between nodes. Data locality is very important to achieve fast pipelines.
The second problem is ths at our data is skewed by nature. Even with infinite bandwidth (instant shuffle), cities vary in size. Cities like New York will have millions and millions of plays, while a small town will have just a few. When we group by song play and city, we are sending all the plays of a city to the same node. This translates to some nodes finishing in seconds and others taking hours to finish. Even more, RDD's groupBy requires all the entries to fit into the memory of the destination node. The Datasets implementation doesn't require it, but we will still need to process them all in the same node.
## Second approach
The main problem of our first approach was to shuffle too early. This ended up causing OOM problems or too much processing per node due to skewed data. To improve it, what if we first calculate the number of plays of each song in a city and shuffle that instead of all the plays?
def cityToSongCount(plays: RDD[SongPlay]) = {
val songCityCount = plays
.map(p => p.song -> p.user.city)
.map(_ -> 1)
.reduceByKey(_+_)
songCityCount.map {
case ((song, city), count) => (city, (song, count))
}
}
def topSongsByCity(songPlays: RDD[SongPlay], numTop: Int) = {
cityToSongCount(songPlays).groupBy(_._1).map {
case (city, songCounts) =>
city -> songCounts.map(_._2).toSeq.sortBy(-_._2).take(numTop)
}
}
Using reduceByKey is performant. Why? because it doesn't shuffle all the values as we did. Firstly, it sums the number of values in each node. Then, it shuffles just the pairs of (value, count), which are finally added in the destination node.
Even though we introduced a big improvement, we are still shuffling all the songs played in a city. Our job will probably not fail, but it will last more than it should. This is because our music streaming service is big enough to provide our users with a huge amount of songs. So, again, big cities will have played millions of songs. Can we do better than that?
## The final approach
In our second approach, we delayed the big shuffle from song plays to songs with their number of plays in a city. We did this using a function that does a lot of the work in each node before shuffling data. Can we find a way to do more work like that before shuffling?
We can deduce that, in the worst case, all top songs of a city could have ended up in a single node after counting them. This tells us that the minimum shuffle we must perform to get a correct solution is numTop songs per node. So, we can process the top songs by city in each node and then shuffle them. In fact, we are reducing the shuffled data from $$O(\text{songs} \cdot \text{cities})$$ to $$O(\text{numTop} \cdot \text{cities})$$, where numTop will be a lot smaller than the total number of songs. After shuffling, we just have to repeat the process in the destination node.
## A performant way to get the top elements of a sequence
We have ended up reducing our problem to getting the top elements of a sequence both before and after the shuffle. In the first two approaches, we did that sorting the sequence in descending order and tooking the first numTop elements. This required $$O(n \log n)$$ time and $$O(n)$$ space. We can reduce that to effectively $$O(n)$$ time and $$O(1)$$ space using a bounded min-heap.
### Bounded min-heap
A min-heap is a binary tree such as the data in each node is less than (or equal) to the data in both of its children. This means that the minimum element of the whole tree is at the root.
We can use a min-heap with a little tweak to get the top elements without storing all of them:
1. Start with an empty heap, with it's sorting defined by the number of plays in ascending order. Along with it, we will also be tracking the number of elements in the tree.
2. For each song, we check the number of elements:
• If it's less than numTop, we just insert the song into the heap
• If it's equals to it, we retrieve the root (the song with the minimum number of plays) and compare it to the song being processed. If the new song has more plays, we remove the current root and we introduce the new song to the heap.
Retrieving the root can be done in constant time, while deleting it is done in $$O(\log \text{numTop})$$ (logarithm of the number of elements in the heap). Inserting new elements depend on the implementation of the heap, but it ranges from logarithmic to constant time.
The total time of the algorithm is $$O(n \log \text{numTop})$$, but as our numTop will probably be a small number, we can say this is effectively linear. We also just need to store into memory a maximum of numTop elements, so it's also effectively constant space.
Heaps are used to implement an abstract data structure called priority queue. The idea is the same, but priority queues expose 3 methods: offer (to insert and element), peek (to retrieve the min element) and poll (to retrieve the min element and also remove it). Knowing this, we can use the Java's priority queue to implement the data structure whe saw before:
import java.util.PriorityQueue
class BoundedPriorityQueue[A](n: Int, ordering: Ordering[A]) {
import scala.collection.convert.wrapAsScala._
private val underlying = new PriorityQueue[A](n, ordering)
def all: Seq[A] = underlying.iterator.toSeq
def +=(element: A): BoundedPriorityQueue[A] = {
if (underlying.size < n) {
underlying.offer(element)
} else {
val min = underlying.peek()
if (min != null && ordering.gt(element, min)) {
underlying.poll()
underlying.offer(element)
}
}
this
}
def ++=(xs: BoundedPriorityQueue[A]): BoundedPriorityQueue[A] = {
xs.all.foreach(this += _)
this
}
def poll(): A = underlying.poll()
}
## Using the priority queue
Now, we just need to use the priority queue to solve the problem for each key both before and after the shuffling. In Spark, this is called aggregateByKey. It takes 3 parameters:
• An empty value for each key.
• A fold function to apply to each element of the key and an accumulated value before shuffling.
• A function to combine the folded values of each node after shuffling.
In our case, the 3 parameters would be:
• An empty BoundedPriorityQueue of songs and their count, sorted by the count in descending order.
• The += method of the bounded priority queue.
• The ++= method of the bounded priority queue.
def topSongsByCity(songPlays: RDD[SongPlay], numTop: Int) = {
val ordering = Ordering.by[(Song, Int), Int](_._2)
cityToSongCount(songPlays).aggregateByKey(
new BoundedPriorityQueue[(Song, Int)](numTop, ordering)
)(
seqOp = (queue, item) => queue += item,
combOp = (queueA, queueB) => queueA ++= queueB
)
.mapValues(_.all)
// We still need to sort them, as we were storing them in a min-heap
// and we want the top ones
.mapValues(_.sorted(ordering.reverse))
}
import org.apache.spark.mllib.rdd.MLPairRDDFunctions._ | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.2143748253583908, "perplexity": 1729.9451310889463}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-21/segments/1652662627464.60/warc/CC-MAIN-20220526224902-20220527014902-00625.warc.gz"} |
http://mathhelpforum.com/calculus/185364-cannot-find-limit-sequence-because-non-factoring-fraction-print.html | # cannot find limit of a sequence because of a non factoring fraction
• July 30th 2011, 02:30 PM
Melsi
cannot find limit of a sequence because of a non factoring fraction
Hello,
I am trying to find the limit of this sequence:
$\sqrt[n]{\frac{k^{n}+l^{n}}{k^{2n}+l^{2n}}}, k,l>0$
but I cannot factorize the fraction at all.
Any idea is very much appreciated!
Thank you all!
• July 30th 2011, 02:47 PM
Plato
Re: cannot find limit of a sequence because of a non factoring fraction
Quote:
Originally Posted by Melsi
I am trying to find the limit of this sequence:
$\sqrt[n]{\frac{k^{n}+l^{n}}{k^{2n}+l^{2n}}}, k,l>0$
You should know this theorem:
If $0 then $\left( {\sqrt[n]{{a^n + b^n }}} \right) \to b$.
• July 30th 2011, 03:03 PM
Melsi
Re: cannot find limit of a sequence because of a non factoring fraction
Hello,
no it is the very first time I see this theorem, I will check it out tomorrow (02:00 at midnight now) and come back with a full solution!
Very kind of you!
Thank you very much!
• July 30th 2011, 03:17 PM
Plato
Re: cannot find limit of a sequence because of a non factoring fraction
Here is the proof of that theorem.
$b = \sqrt[n]{{b^n }} \leqslant{\color{blue} \sqrt[n]{{a^n + b^n }}} \leqslant \sqrt[n]{{b^n + b^n }} = b\sqrt[n]{2} \to b$
• July 31st 2011, 12:13 AM
Melsi
Solved!
The proof... that's a good one, cool! Now it can be solved..
the initial formula of the general term could be written like this:
$\sqrt[n]{\frac{k^{n}+l^{n}}{k^{2n}+l^{2n}}}=\frac{(k^{n}+l ^{n})^{1/n}}{(k^{2n}+l^{2n})^{1/n}}$
and the limit like this:
$\lim_{n \to \infty}{a_{n}=\lim_{n\to \infty }\frac{(k^{n}+l^{n})^{1/n}}{(k^{2n}+l^{2n})^{1/n}}=\frac{\lim_{n\to \infty }(k^{n}+l^{n})^{1/n}}{\lim_{n\to \infty }(k^{2n}+l^{2n})^{1/n}}$
if we apply the theorem for the numerator we have:
$l\leq \lim_{n\to \infty }(k^{n}+l^{n})^{1/n}\leq \lim_{n\to \infty }(l+\sqrt[n]{2})\Leftrightarrow \lim_{n\to \infty }(k^{n}+l^{n})^{1/n} = l$
and for the denominator it goes like this:
$l^{2}\leq \lim_{n\to \infty }(k^{2n}+l^{2n})^{1/n}\leq \lim_{n\to \infty }(l^{2}+\sqrt[n]{2})\Leftrightarrow \lim_{n\to \infty }(k^{2n}+l^{2n})^{1/n} = l^{2}$
Finally having found those two limits we can write:
$\lim_{n \to \infty}a_{n}=\frac{l}{l^{2}}=\frac{1}{l}$
and all these supposing that $a\leq b$ and $a,b> 0$ this means that if $b\leq a$ it will go the other way around, the limit will be
$\frac{1}{k}$
Thank you once again, for your valuable help!(Hi) | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 14, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9980689883232117, "perplexity": 10023.625496256343}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-41/segments/1410657134620.5/warc/CC-MAIN-20140914011214-00050-ip-10-234-18-248.ec2.internal.warc.gz"} |
http://mathhelpforum.com/algebra/652-urgent.html | # Math Help - Urgent
1. ## Urgent
What is area of a rectangle with a width of 12 feet and length of 10 feet?
2. 120 feet. Area of a rectangle is length times width. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8606848120689392, "perplexity": 813.8873660830043}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-22/segments/1432207928350.51/warc/CC-MAIN-20150521113208-00301-ip-10-180-206-219.ec2.internal.warc.gz"} |
https://www.geteasysolution.com/what-is-0.006-percent-of-545000 | # What is 0.006 percent of 545000 - step by step solution
## Simple and best practice solution for 0.006% of 545000. Check how easy it is, and learn it for the future. Our solution is simple, and easy to understand, so don`t hesitate to use it as a solution of your homework.
If it's not what You are looking for type in the calculator fields your own values, and You will get the solution.
To get the solution, we are looking for, we need to point out what we know.
1. We assume, that the number 545000 is 100% - because it's the output value of the task.
2. We assume, that x is the value we are looking for.
3. If 545000 is 100%, so we can write it down as 545000=100%.
4. We know, that x is 0.006% of the output value, so we can write it down as x=0.006%.
5. Now we have two simple equations:
1) 545000=100%
2) x=0.006%
where left sides of both of them have the same units, and both right sides have the same units, so we can do something like that:
545000/x=100%/0.006%
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.
7. Solution for what is 0.006% of 545000
545000/x=100/0.006
(545000/x)*x=(100/0.006)*x - we multiply both sides of the equation by x
545000=16666.666666667*x - we divide both sides of the equation by (16666.666666667) to get x
545000/16666.666666667=x
32.7=x
x=32.7
now we have:
0.006% of 545000=32.7 | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8080384135246277, "perplexity": 444.32996688332065}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-16/segments/1585371813538.73/warc/CC-MAIN-20200408104113-20200408134613-00007.warc.gz"} |
https://mathshistory.st-andrews.ac.uk/Biographies/Hadamard/ | Jacques Salomon Hadamard
Quick Info
Born
8 December 1865
Versailles, France
Died
17 October 1963
Paris, France
Summary
Jacques Hadamard was a French mathematician whose most important result is the prime number theorem which he proved in 1896. This states that the number of primes < n tends to infinity as fast as n/log e n.
Biography
Jacques Hadamard's father, Amédée Hadamard, married Claire Marie Jeanne Picard on 6 June 1864. Amédée Hadamard, who was of a Jewish background, was a teacher who taught several subjects such as classics, grammar, history and geography while Jacques' mother taught piano giving private lessons in their home. At the time that Jacques was born Amédée was teaching at the Lycée Impérial in Versailles but the family moved to Paris when Jacques was three years old when his father took up a position at the Lycée Charlemagne.
This was an unfortunate time for a child to be growing up in Paris. The Franco-Prussian War which began on 19 July 1870 went badly for France and on 19 September 1870 the Prussians began a siege of Paris. This was a desperate time for the inhabitants of the town who killed their horses, cats and dogs for food. Hadamard's family, like many others, ate elephant meat to survive. Paris surrendered on 28 January 1871 and the Treaty of Frankfurt, signed on 10 May 1871, was a humiliation for France. Between the surrender and the signing of the treaty there was essentially a civil war in Paris and the Hadamards' house was burnt down.
The war was not the only cause of sadness for the Hadamards. Jacques' young sister Jeanne died in 1870 before the siege of Paris and another sister Suzanne, who was born in 1871, died in 1874.
Jacques began his schooling at the Lycée Charlemagne where his father taught. In his first few years at school he was good at all subjects except mathematics. He excelled in particular in Greek and Latin. He wrote in 1936:-
... in arithmetic, until the fifth grade, I was last or nearly last.
He was not accurate in this statement, for although at first it is true he was weak in arithmetic, by the fifth class he was placed second in his class at the Lycée. By this time (1875) he was winning prizes in many subjects in the Concours Général, the national competition for school pupils. It was a good mathematics teacher who turned him towards mathematics and science, when he was in this fifth class.
In 1875 Hadamard's father, having acquired a poor reputation as a teacher, was transferred to the Lycée Louis-le-Grand and Jacques attended this school from 1876. In 1882 he graduated Bachelier ès lettres et ès sciences then, in the following year, he received his Baccalauréat ès sciences. He was awarded first prize in algebra and first prize in mechanics in the Concours Général of 1883.
In 1884 Hadamard took the entrance examinations for École Polytechnique and École Normale Supérieure; he was placed first in both examinations. He chose the École Normale Supérieure, where he soon made friends with his fellow students including Duhem and Painlevé. Among his teachers were Jules Tannery, Hermite, Darboux, Appell, Goursat and Émile Picard. Already at this stage he began to undertake research, investigating the problem of finding an estimate for the determinant generated by coefficients of a power series. He graduated from the École Normale Supérieure on 30 October 1888.
While undertaking research for his doctorate he worked as a school teacher. At first he was attached to the Lycée de Caen but without teaching duties. From June 1889 he taught at the Lycée Saint-Louis and then from September 1890 at the Lycée Buffon where he taught for three years. Although his research went extremely well, his teaching was less appreciated, probably because he demanded more of his pupils than their abilities allowed. His one great success was teaching Fréchet, and the two corresponded over a period of about nine years.
Hadamard obtained his doctorate in 1892 for a thesis on functions defined by Taylor series. This work on functions of a complex variable was one of the first to examine the general theory of analytic functions, in particular his thesis contained the first general work on singularities.
In the same year Hadamard received the Grand Prix des Sciences Mathématiques for his paper Determination of the number of primes less than a given number. The topic proposed for the prize, concerning filling gaps in Riemann's work on zeta functions, had been put forward by Hermite with his friend Stieltjes in mind. Stieltjes had claimed in 1885 to have proved the Riemann hypothesis but had never published his "proof" and, after the prize topic was announced in 1890, Stieltjes discovered a gap in his "proof" which he was unable to fill. He never submitted an entry for the prize but Hadamard, between the time his thesis was submitted and his oral examination, realised that his results could be applied to zeta functions. His paper on entire functions and zeta functions was awarded first prize.
The year 1892 was significant for Hadamard in addition to the academic achievements described above. In June of that year he married Louise-Anna Trénel who was, like Hadamard, of a Jewish background. They had known each other from childhood and shared a love of music. They moved to Bordeaux the following year when Hadamard was appointed as a lecturer at the University. If he had failed to come up to scratch as a teacher at the Lycée Buffon, this was far from the case now, for he impressed everyone with both his research and teaching skills. On 1 February 1896 he was appointed as Professor of Astronomy and Rational Mechanics at Bordeaux.
The four years which he spent in Bordeaux were not only busy ones for his family life, with two sons Pierre and Étienne being born during this time, but they were also extremely productive ones for Hadamard's research. He published 29 papers during these four years, but they are remarkable more for their depth and the range of the topics which they covered rather than their number. Perhaps his most important result proved during this time was the prime number theorem which he proved in 1896. This states that:-
The number of primes ≤ $n$ tends to ∞ as $n/\ln n$.
This theorem was conjectured in the 18th century, but it was not proved until 1896, when Hadamard and (independently) Charles de la Vallée Poussin, used complex analysis. The proof had been outlined by Riemann in 1851, but the necessary tools had not been developed at that time. This problem was one of the major motivations for the development of complex analysis from 1851 to 1896 when Riemann's outlined proof was finally completed.
Solving this important open problem was not Hadamard's only remarkable contribution of 1896. In the same year he published a paper on properties of dynamic trajectories which won the Bordin Prize of the Academy of Sciences. The topic proposed for the prize had been one on geodesics and Hadamard's work in studying the trajectories of point masses on a surface led to certain non-linear differential equations whose solution also gave properties of geodesics. His work was therefore a major contribution to both geometry and to dynamics.
Another result which Hadamard published during his time in Bordeaux was his famous determinant inequality of 1893. Matrices whose determinants satisfied equality in the relation are today called Hadamard matrices and are important in the theory of integral equations, coding theory and other areas.
Hadamard first became involved in politics during his time in Bordeaux. Alfred Dreyfus, whose wife was a relation of Hadamard, came from Alsace. Born into a Jewish family, Dreyfus embarked on a military career. In 1894, when he was in the War Ministry, he was accused of selling military secrets to the Germans and he was sentenced to life imprisonment. Although his trial had been highly irregular, the anti-Semitic views of many people made the verdict popular. Forged documents and cover-ups soon showed that the legal process had been suspect. At first Hadamard, like many people, assumed that Dreyfus was guilty. However after moving to Paris in 1897 he began to discover how evidence against Dreyfus had been forged. He became a leading member of those trying to correct the injustice. Painlevé described a conversation he had with Hadamard on the matter in 1897 (see for example [6]):-
For almost an hour, [Hadamard] tried to convince me of Dreyfus's innocence, and at the end, faced with my disbelief, he did his best to make me understand the intrinsic value of his arguments and his complete lack of passion and sentimentality ... he based his belief in his innocence on the facts.
In 1898 the novelist Émile Zola wrote an open letter accusing the army of covering up its mistaken conviction of Dreyfus. The case split France into two opposing camps leading to issues far beyond the guilt or innocence of Dreyfus. There were demands to bring Zola to justice, anti-Semitic riots broke out, and there was a petition demanding that Dreyfus be retried. Zola was sentenced to a year in prison and fined 3,000 francs. By 1899 there had been a confession to the forgeries, followed by a suicide, and Dreyfus was retried, again found guilty, but pardoned. Hadamard took an active part in clearing Dreyfus's name which finally happened on 22 July 1906, when Dreyfus was reinstated and decorated with the Legion of Honour. Laurent Schwartz wrote (see for example [27]):-
It is the Dreyfus Affair which was in the sense of defence of justice the great affair of [Hadamard's] life. From the moment when he understood the enormity of the injustice perpetrated against a man in the name of reason of state, and the consequences which anti-Semitism could have, he devoted himself passionately to the review of the trial. This affair marked his life.
Long before the Dreyfus Affair had ended Hadamard had, as we have indicated, moved from Bordeaux to Paris. In 1897 he resigned his chair in Bordeaux to take up lesser posts, one in the Faculty of Science of the Sorbonne and one at the Collège de France. Soon after arriving in Paris in October 1897, he published the first volume of Leçons de Géométrie Elémentaire . This volume on two dimensional geometry appeared in 1898, and was followed by a second volume on three dimensional geometry in 1901. This work had been requested by Darboux and it went on to have a major influence on the teaching of mathematics in France.
Hadamard received the Prix Poncelet in 1898 for his research achievements over the preceding ten years. His research turned more towards mathematical physics from the time he took up the posts in Paris, yet he always argued strongly that he was a mathematician, not a physicist. He believed that it was the rigour of his work which made it mathematics. In particular he worked on the partial differential equations of mathematical physics producing results of outstanding importance. His famous 1898 work on geodesics on surfaces of negative curvature laid the foundations of symbolic dynamics. Among the topics he considered were elasticity, geometrical optics, hydrodynamics and boundary value problems. He introduced the concept of a well-posed initial value and boundary value problem.
During Hadamard's first five years in Paris another three children were born, first another son Mathieu and then two daughters Cécile and Jacqueline. He continued to receive prizes for his research and he was further honoured in 1906 with election as President of the French Mathematical Society. In 1909 he was appointed to the chair of mechanics at the Collège de France. In the following year he published Leçons sur le calcul des variations which helped lay the foundations of functional analysis (he introduced the word functional). Then in 1912 he was appointed as professor of analysis at the École Polytechnique where he succeed Jordan.
Poincaré had strongly supported Hadamard for this chair but, within a few months, he died at the tragically young age of 58. Hadamard then undertook the hugely difficult task of surveying Poincaré's work and by the end of the summer of 1912 he had produced two major articles. As Paul Lévy wrote:-
One had to be Hadamard to dare to undertake the exposition of all of [Poincaré's] immense work which dealt with so many different areas, and to finish it in one summer.
Near the end of 1912 Hadamard was elected to the Academy of Sciences to succeed Poincaré. He wrote later that his many years of "pure joy", beginning from the time of his marriage, came to an end in 1916. It was World War I which led to a great tragedy for Hadamard with his two older sons being killed in action. Both were killed at Verdun and Hadamard was lecturing in Rome when Pierre was killed. He left before receiving the news which he did not discover until arriving back in Paris despite the best efforts of Fano, Volterra's wife and others to get news to him. Étienne was killed near Verdun about two months later.
Hadamard knew only one way to push the pain of these tragedies away enough to allow him to keep going, and that was to throw himself even more vigorously into mathematics. He was appointed to Appell's chair of analysis at the École Centrale in 1920 but retained his positions in the École Polytechnique and the Collège de France. During the years between his appointment and 1933 he travelled widely visiting the United States twice, Spain, Czechoslovakia, Italy, Switzerland, Brazil, Argentina, and Egypt.
He continued to produce books and papers of the highest quality, publishing perhaps his most famous text Lectures on Cauchy's problem in linear partial differential equations in 1922. The book was based on a lecture course he had given at Yale University in the United States. He also took up new topics, writing several papers on probability theory, in particular on Markov chains. He also published many articles on mathematical education and education in general.
Between the wars Hadamard's politics moved towards the left, mainly in response to the Nazis rise to power in 1933. After the start of World War II, when France fell in 1940, Hadamard and his family escaped to the United States where he was appointed to a visiting position at Columbia University. However, he failed to find a permanent post in America and in 1944 received the terrible news that his third son Mathieu had been killed in the war. Hadamard left the United States soon after and spent a year in England before returning to Paris as soon as was possible after the end of the war.
After the War he became an active peace campaigner and it required the strong support of mathematicians in the USA to allow him to enter the country for the International Congress in Cambridge, Massachusetts in 1950. He was made honorary president of the Congress.
One further tragedy was to hit Hadamard before his death. In 1962, when he was 96 years old, his grandson Étienne was killed in a mountaineering accident. This seemed to finally kill Hadamard's spirit and he did not leave his house after this, almost waiting to die.
The following tribute is paid in [3]:-
Hadamard was the doyen not only of the Academy of Sciences, to which he was elected in December 1912, in the seat left vacant by the death of Henri Poincaré, but of the entire Institut de France. In December last year, he was formally presented with a gold medal specially struck to commemorate the fiftieth anniversary of his election to the academy, and tributes were paid to him by scientists all over the world.
There is no way that an article of this length can even indicate the range of Hadamard's mathematical contributions. As well as about 300 scientific papers and books Hadamard also wrote books for a wider audience. His book The psychology of invention in the mathematical field (1945) is a wonderful work about mathematics. We should also, however, indicate Hadamard's style of teaching. At the conference to celebrate the centenary of his birth, one of his students said he had been taught by:-
... a teacher who was active, alive, whose reasoning combined exactness and dynamism. Thus the lecture became a struggle and an adventure. Without rigour suffering, the importance of intuition was restored to us, and the better students were delighted.
Laurent Schwartz spoke about Hadamard at this ceremony held to celebrate the centenary of Hadamard's birth:-
I believe that he had a fantastic influence on his time, and that all living analysts were shaped by him, directly or indirectly.
References (show)
1. S Mandelbrojt, Biography in Dictionary of Scientific Biography (New York 1970-1990). See THIS LINK.
2. Biography in Encyclopaedia Britannica. http://www.britannica.com/biography/Jacques-Salomon-Hadamard
3. M L Cartwright, Jacques Hadamard, Biographical Memoirs of Fellows of the Royal Society of London 2 (1965).
4. P Lévy, S Mandelbrojt, B Malgrange and P Malliavin, La vie et l'oeuvre de Jacques Hadamard (1865-1963), Monographie de l'Enseignement Mathématique Institut de Mathématiques de l'Université de Genève 16 (Geneva 1967).
5. V Maz'ya and T Shaposhnikova, Jacques Hadamard, a universal mathematician (London, 1998).
6. Bibliographie des oeuvres de Jacques Hadamard, Enseignement Math. (2) 13 (1967), 53-72.
7. M L Cartwright, Jacques Hadamard, J. London Math. Soc. 40 (1965), 722-748.
8. M L Cartwright, Jacques Hadamard, Biographical Memoirs of Fellows of the Royal Society 11 (1965), 75-98.
9. R Djordjevic, On Hadamard's ideas about the nature of the creative process in mathematics (Serbian), in Serbian contributions to the mathematical sciences (Belgrade, 1992), 168-174.
10. M Fréchet, Jacques Hadamard, Pensée 112 (1963), 102-104.
11. J D Gray, Comments on collected works, in particular those of Emile Borel and Jacques Hadamard, Historia Mathematica 3 (2) (1976), 203-206.
12. J Gray, König, Hadamard and Kürschák, and abstract algebra, Math. Intelligencer 19 (2) (1997), 61-64.
13. P Günther, Huygens' principle and Hadamard's conjecture, The Mathematical Intelligencer 13 (2) (1991), 56-63.
14. H Heilbrown and L Howarth, Jacques Hadamard, Nature 200 (1963), 937-938.
15. J-P Kahane, Jacques Hadamard, The Mathematical Intelligencer 13 (1) (1991), 23-29.
16. J-P Kahane, Hadamard et la stabilité du système solaire, in Travaux mathématiques XI, Luxembourg, 1998 (Luxembourg, 1999), 33-48.
17. U Kirchgraber, Als Poincaré, Hadamard und Perron die invarianten Mannigfaltigkeiten entdeckten, Math. Semesterber. 44 (2) (1997), 153-171.
18. P Lévy, Jacques Hadamard, sa vie et son oeuvre : Calcul fonctionnel et questions diverses, L'Enseignement Mathématique (2) 13 (1967), 1-24.
19. P Lévy, Jacques Hadamard (Russian), Uspekhi matematicheskikh nauk 19 (3) (117) (1964), 163-182.
20. A M Maeder, Jacques Hadamard (Portugese), Boletim Soc. Paranaense Mat. 7 (1963), 5-7.
21. P Malliavin, Quelques aspects de l'oeuvre de Jacques Hadamard en géométrie, L'Enseignement Mathématique (2) 13 (1967), 49-52.
22. S Mandelbrojt, Théorie des fonctions et théorie des nombres dans l'oeuvre de Jacques Hadamard, L'Enseignement Mathématique (2) 13 (1967), 25-34.
23. S Mandelbrojt, The mathematical work of Jacques Hadamard, The American Mathematical Monthly 60 (1953), 599-604.
24. S Mandelbrojt and L Schwartz, Jacques Hadamard (1865-1963), Bull. Amer. Math. Soc. 71 (1965), 107-129.
25. S Ou, The fiftieth anniversary of Hadamard's scientific journey to China (Chinese), Adv. in Math. (Beijing) 18 (1) (1989), 62-67.
26. S Rossat-Mignod and A Rossat-Mignod, Jacques Hadamard, Les Cahiers Rationalistes 269 (1969), 306-358.
27. F G Tricomi, Commemorazione del socio straniero Jacques Hadamard, Atti della Reale Accademia dei Lincei (5) 39 (1965), 375-379.
Additional Resources (show)
Other pages about Jacques Hadamard:
Other websites about Jacques Hadamard:
Honours (show)
Honours awarded to Jacques Hadamard
Cross-references (show)
Written by J J O'Connor and E F Robertson
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https://brilliant.org/problems/its-too-hard-to-come-up-with-cool-names-for/ | # Its too hard to come up with cool names for integrals
Calculus Level 5
Evaluate the following:
$\int_0^{\infty} \frac{x^3-\sin^3x}{x^5}\,dx$
If the result can be expressed as $$\dfrac{a\pi^b}{c}$$ where $$a$$ and $$c$$ are coprime. Find $$a+b+c$$.
× | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.728099524974823, "perplexity": 524.6412268981928}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-17/segments/1524125947654.26/warc/CC-MAIN-20180425001823-20180425021823-00616.warc.gz"} |
https://casmusings.wordpress.com/tag/cell-phones/ | # Tag Archives: cell phones
## Great Probability Problems
UPDATE: Unfortunately, there are a couple errors in my computations below that I found after this post went live. In my next post, Mistakes are Good, I fix those errors and reflect on the process of learning from them.
ORIGINAL POST:
A post last week to the AP Statistics Teacher Community by David Bock alerted me to the new weekly Puzzler by Nate Silver’s new Web site, http://fivethirtyeight.com/. As David noted, with their focus on probability, this new feature offers some great possibilities for AP Statistics probability and simulation.
I describe below FiveThirtyEight’s first three Puzzlers along with a potential solution to the last one. If you’re searching for some great problems for your classes or challenges for some, try these out!
THE FIRST THREE PUZZLERS:
The first Puzzler asked a variation on a great engineering question:
You work for a tech firm developing the newest smartphone that supposedly can survive falls from great heights. Your firm wants to advertise the maximum height from which the phone can be dropped without breaking.
You are given two of the smartphones and access to a 100-story tower from which you can drop either phone from whatever story you want. If it doesn’t break when it falls, you can retrieve it and use it for future drops. But if it breaks, you don’t get a replacement phone.
Using the two phones, what is the minimum number of drops you need to ensure that you can determine exactly the highest story from which a dropped phone does not break? (Assume you know that it breaks when dropped from the very top.) What if, instead, the tower were 1,000 stories high?
The second Puzzler investigated random geyser eruptions:
You arrive at the beautiful Three Geysers National Park. You read a placard explaining that the three eponymous geysers — creatively named A, B and C — erupt at intervals of precisely two hours, four hours and six hours, respectively. However, you just got there, so you have no idea how the three eruptions are staggered. Assuming they each started erupting at some independently random point in history, what are the probabilities that A, B and C, respectively, will be the first to erupt after your arrival?
Both very cool problems with solutions on the FiveThirtyEight site. The current Puzzler talked about siblings playing with new phone apps.
SOLVING THE CURRENT PUZZLER:
Before I started, I saw Nick Brown‘s interesting Tweet of his simulation.
If Nick’s correct, it looks like a mode of 5 minutes and an understandable right skew. I approached the solution by first considering the distribution of initial random app choices.
There is a $\displaystyle \frac{5}{25}$ chance the siblings choose the same app and head to dinner after the first round. The expected length of that round is $\frac{1}{5} \cdot \left( 1+2=3=4+5 \right) = 3$ minutes.
That means there is a $\displaystyle \frac{4}{5}$ chance different length apps are chosen with time differences between 1 and 4 minutes. In the case of unequal apps, the average time spent before the shorter app finishes is $\frac{1}{25} \cdot \left( 8*1+6*2+4*3+2*4 \right) = 1.6$ minutes.
It doesn’t matter which sibling chose the shorter app. That sibling chooses next with distribution as follows.
While the distributions are different, conveniently, there is still a time difference between 1 and 4 minutes when the total times aren’t equal. That means the second table shows the distribution for the 2nd and all future potential rounds until the siblings finally align. While this problem has the potential to extend for quite some time, this adds a nice pseudo-fractal self-similarity to the scenario.
As noted, there is a $\displaystyle \frac{4}{20}=\frac{1}{5}$ chance they complete their apps on any round after the first, and this would not add any additional time to the total as the sibling making the choice at this time would have initially chosen the shorter total app time(s). Each round after the first will take an expected time of $\frac{1}{20} \cdot \left( 7*1+5*2+3*3+1*4 \right) = 1.5$ minutes.
The only remaining question is the expected number of rounds of app choices the siblings will take if they don’t align on their first choice. This is where I invoked self-similarity.
In the initial choice there was a $\frac{4}{5}$ chance one sibling would take an average 1.6 minutes using a shorter app than the other. From there, some unknown average N choices remain. There is a $\frac{1}{5}$ chance the choosing sibling ends the experiment with no additional time, and a $\frac{4}{5}$ chance s/he takes an average 1.5 minutes to end up back at the Table 2 distribution, still needing an average N choices to finish the experiment (the pseudo-fractal self-similarity connection). All of this is simulated in the flowchart below.
Recognizing the self-similarity allows me to solve for N.
$\displaystyle N = \frac{1}{5} \cdot 1 + \frac{4}{5} \cdot N \longrightarrow N=5$
Number of Rounds – Starting from the beginning, there is a $\frac{1}{5}$ chance of ending in 1 round and a $\frac{4}{5}$ chance of ending in an average 5 rounds, so the expected number of rounds of app choices before the siblings simultaneously end is
$\frac{1}{5} *1 + \frac{4}{5}*5=4.2$ rounds
Time until Eating – In the first choice, there is a $\frac{1}{5}$ chance of ending in 3 minutes. If that doesn’t happen, there is a subsequent $\frac{1}{5}$ chance of ending with the second choice with no additional time. If neither of those events happen, there will be 1.6 minutes on the first choice plus an average 5 more rounds, each taking an average 1.5 minutes, for a total average $1.6+5*1.5=9.1$ minutes. So the total average time until both siblings finish simultaneously will be
$\frac{1}{5}*3+\frac{4}{5}*9.1 = 7.88$ minutes
CONCLUSION:
My 7.88 minute mean is reasonably to the right of Nick’s 5 minute mode shown above. We’ll see tomorrow if I match the FiveThirtyEight solution.
Anyone else want to give it a go? I’d love to hear other approaches. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 17, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.641871452331543, "perplexity": 1481.2472348280805}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-24/segments/1590347402457.55/warc/CC-MAIN-20200529054758-20200529084758-00534.warc.gz"} |
https://neugierde.github.io/cantors-attic/Ineffable | # cantors-attic
Climb into Cantor’s Attic, where you will find infinities large and small. We aim to provide a comprehensive resource of information about all notions of mathematical infinity.
View the Project on GitHub neugierde/cantors-attic
# Ineffable cardinal
Ineffable cardinals were introduced by Jensen and Kunen in (Jensen & Kunen, 1969) and arose out of their study of $\diamondsuit$ principles. An uncountable regular cardinal $\kappa$ is ineffable if for every sequence $\langle A_\alpha\mid \alpha<\kappa\rangle$ with $A_\alpha\subseteq \alpha$ there is $A\subseteq\kappa$ such that the set $S=\{\alpha<\kappa\mid A\cap \alpha=A_\alpha\}$ is stationary. Equivalently an uncountable regular $\kappa$ is ineffable if and only if for every function $F:[\kappa]^2\rightarrow 2$ there is a stationary $H\subseteq\kappa$ such that $F\upharpoonright [H]^2$ is constant (Jensen & Kunen, 1969). This second characterization strengthens a characterization of weakly compact cardinals which requires that there exist such an $H$ of size $\kappa$.
If $\kappa$ is ineffable, then $\diamondsuit_\kappa$ holds and there cannot be a slim $\kappa$-Kurepa tree (Jensen & Kunen, 1969). A $\kappa$-Kurepa tree is a tree of height $\kappa$ having levels of size less than $\kappa$ and at least $\kappa^+$-many branches. A $\kappa$-Kurepa tree is slim if every infinite level $\alpha$ has size at most $|\alpha|$.
An uncountable cardinal κ has the normal filter property iff it is ineffable. (Holy & Schlicht, 2018)
## Ineffable cardinals and the constructible universe
Ineffable cardinals are downward absolute to $L$. In $L$, an inaccessible cardinal $\kappa$ is ineffable if and only if there are no slim $\kappa$-Kurepa trees. Thus, for inaccessible cardinals, in $L$, ineffability is completely characterized using slim Kurepa trees. (Jensen & Kunen, 1969)
If $0^\sharp$ exists, then every Silver indiscernible is ineffable in $L$. (Jech, 2003)
Ramsey cardinals are stationary limits of completely ineffable cardinals, they are weakly ineffable, but the least Ramsey cardinal is not ineffable. Ineffable Ramsey cardinals are limits of Ramsey cardinals, because ineffable cardinals are $Π^1_2$-indescribable and being Ramsey is a $Π^1_2$-statement. The least strongly Ramsey cardinal also is not ineffable, but super weakly Ramsey cardinals are ineffable. $1$-iterable (=weakly Ramsey) cardinals are weakly ineffable and stationary limits of completely ineffable cardinals. The least $1$-iterable cardinal is not ineffable. (Holy & Schlicht, 2018; Gitman, 2011)
## Weakly ineffable cardinal
Weakly ineffable cardinals (also called almost ineffable) were introduced by Jensen and Kunen in (Jensen & Kunen, 1969) as a weakening of ineffable cardinals. An uncountable regular cardinal $\kappa$ is weakly ineffable if for every sequence $\langle A_\alpha\mid \alpha<\kappa\rangle$ with $A_\alpha\subseteq \alpha$ there is $A\subseteq\kappa$ such that the set $S=\{\alpha<\kappa\mid A\cap \alpha=A_\alpha\}$ has size $\kappa$. If $\kappa$ is weakly ineffable, then $\diamondsuit_\kappa$ holds.
## Subtle cardinal
Subtle cardinals were introduced by Jensen and Kunen in (Jensen & Kunen, 1969) as a weakening of weakly ineffable cardinals. A uncountable regular cardinal $\kappa$ is subtle if for every for every $\langle A_\alpha\mid \alpha<\kappa\rangle$ with $A_\alpha\subseteq \alpha$ and every closed unbounded $C\subseteq\kappa$ there are $\alpha<\beta$ in $C$ such that $A_\beta\cap\alpha=A_\alpha$. If $\kappa$ is subtle, then $\diamondsuit_\kappa$ holds.
To be expanded.
## $n$-ineffable cardinal
The $n$-ineffable cardinals for $2\leq n<\omega$ were introduced by Baumgartner in (Baumgartner, 1975) as a strengthening of ineffable cardinals. A cardinal is $n$-ineffable if for every function $F:[\kappa]^n\rightarrow 2$ there is a stationary $H\subseteq\kappa$ such that $F\upharpoonright [H]^n$ is constant.
• $2$-ineffable cardinals are exactly the ineffable cardinals.
• an $n+1$-ineffable cardinal is a stationary limit of $n$-ineffable cardinals. (Baumgartner, 1975)
A cardinal $\kappa$ is totally ineffable if it is $n$-ineffable for every $n$.
• a $1$-iterable cardinal is a stationary limit of totally ineffable cardinals. (this follows from material in (Gitman, 2011))
### Helix
(Information in this subsection come from (Friedman, 1998) unless noted otherwise.)
For $k \geq 1$ we define:
• $\mathcal{P}(x)$ is the powerset (set of all subsets) of $x$. $\mathcal{P}_k(x)$ is the set of all subsets of $x$ with exactly $k$ elements.
• $f:\mathcal{P}_k(\lambda) \to \mathcal{P}(\lambda)$ is regressive iff for all $A \in \mathcal{P}_k(\lambda)$, we have $f(A) \subseteq \min(A)$.
• $E$ is $f$-homogenous iff $E \subseteq \lambda$ and for all $B,C \in \mathcal{P}_k(E)$, we have $f(B) \cap \min(B \cup C) = f(C) \cap \min(B \cup C)$.
• $\lambda$ is $k$-subtle iff $\lambda$ is a limit ordinal and for all clubs $C \subseteq \lambda$ and regressive $f:\mathcal{P}_k(\lambda) \to \mathcal{P}(\lambda)$, there exists an $f$-homogenous $A \in \mathcal{P}_{k+1}(C)$.
• $\lambda$ is $k$-almost ineffable iff $\lambda$ is a limit ordinal and for all regressive $f:\mathcal{P}_k(\lambda) \to \mathcal{P}(\lambda)$, there exists an $f$-homogenous $A \subseteq \lambda$ of cardinality $\lambda$.
• $\lambda$ is $k$-ineffable iff $\lambda$ is a limit ordinal and for all regressive $f:\mathcal{P}_k(\lambda) \to \mathcal{P}(\lambda)$, there exists an $f$-homogenous stationary $A \subseteq \lambda$.
$0$-subtle, $0$-almost ineffable and $0$-ineffable cardinals can be defined as “uncountable regular cardinals” because for $k \geq 1$ all three properties imply being uncountable regular cardinals.
• For $k \geq 1$, if $\kappa$ is a $k$-ineffable cardinal, then $\kappa$ is $k$-almost ineffable and the set of $k$-almost ineffable cardinals is stationary in $\kappa$.
• For $k \geq 1$, if $\kappa$ is a $k$-almost ineffable cardinal, then $\kappa$ is $k$-subtle and the set of $k$-subtle cardinals is stationary in $\kappa$.
• For $k \geq 1$, if $\kappa$ is a $k$-subtle cardinal, then the set of $(k-1)$-ineffable cardinals is stationary in $\kappa$.
• For $k \geq n \geq 0$, all $k$-ineffable cardinals are $n$-ineffable, all $k$-almost ineffable cardinals are $n$-almost ineffable and all $k$-subtle cardinals are $n$-subtle.
This structure is similar to the double helix of $n$-fold variants and earlier known although smaller. (Kentaro, 2007)
## Completely ineffable cardinal
Completely ineffable cardinals were introduced in (Abramson et al., 1977) as a strengthening of ineffable cardinals. Define that a collection $R\subseteq P(\kappa)$ is a stationary class if
• $R\neq\emptyset$,
• for all $A\in R$, $A$ is stationary in $\kappa$,
• if $A\in R$ and $B\supseteq A$, then $B\in R$.
A cardinal $\kappa$ is completely ineffable if there is a stationary class $R$ such that for every $A\in R$ and $F:[A]^2\to2$, there is $H\in R$ such that $F\upharpoonright [H]^2$ is constant.
Relations:
## References
1. Jensen, R., & Kunen, K. (1969). Some combinatorial properties of L and V. http://www.mathematik.hu-berlin.de/ raesch/org/jensen.html
2. Holy, P., & Schlicht, P. (2018). A hierarchy of Ramsey-like cardinals. Fundamenta Mathematicae, 242, 49–74. https://doi.org/10.4064/fm396-9-2017
3. Jech, T. J. (2003). Set Theory (Third). Springer-Verlag. https://logic.wikischolars.columbia.edu/file/view/Jech%2C+T.+J.+%282003%29.+Set+Theory+%28The+3rd+millennium+ed.%29.pdf
4. Gitman, V. (2011). Ramsey-like cardinals. The Journal of Symbolic Logic, 76(2), 519–540. http://boolesrings.org/victoriagitman/files/2011/08/ramseylikecardinals.pdf
5. Abramson, F., Harrington, L., Kleinberg, E., & Zwicker, W. (1977). Flipping properties: a unifying thread in the theory of large cardinals. Ann. Math. Logic, 12(1), 25–58.
6. Nielsen, D. S., & Welch, P. (2018). Games and Ramsey-like cardinals.
7. Friedman, H. M. (1998). Subtle cardinals and linear orderings. https://u.osu.edu/friedman.8/files/2014/01/subtlecardinals-1tod0i8.pdf
8. Hamkins, J. D., & Johnstone, T. A. (2014). Strongly uplifting cardinals and the boldface resurrection axioms.
9. Rathjen, M. (2006). The art of ordinal analysis. http://www.icm2006.org/proceedings/Vol_II/contents/ICM_Vol_2_03.pdf
10. Baumgartner, J. (1975). Ineffability properties of cardinals. I. In Infinite and finite sets (Colloq., Keszthely, 1973; dedicated to P. Erdős on his 60th birthday), Vol. I (pp. 109–130. Colloq. Math. Soc. János Bolyai, Vol. 10). North-Holland.
11. Kentaro, S. (2007). Double helix in large large cardinals and iteration of elementary embeddings. Annals of Pure and Applied Logic, 146(2-3), 199–236. https://doi.org/10.1016/j.apal.2007.02.003
12. Sharpe, I., & Welch, P. (2011). Greatly Erdős cardinals with some generalizations to the Chang and Ramsey properties. Ann. Pure Appl. Logic, 162(11), 863–902. https://doi.org/10.1016/j.apal.2011.04.002
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https://ch.gateoverflow.in/955/gate-chemical-2019-ga-question-7 | In the given diagram, teachers are represented in the triangle, researchers in the circle and administrators in the rectangle. Out of the total number of the people, the percentage of administrators shall be in the range of _______
1. $0$ to $15$
2. $16$ to $30$
3. $31$ to $45$
4. $46$ to $60$ | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6449201703071594, "perplexity": 447.81342271074465}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-21/segments/1652662658761.95/warc/CC-MAIN-20220527142854-20220527172854-00269.warc.gz"} |
https://en.wikibooks.org/wiki/Fundamentals_of_Transportation/Earthwork | # Fundamentals of Transportation/Earthwork
The dump truck is amongst the equipment necessary for earthwork to occur
Earthwork is something that transportation projects seldom avoid. In order to establish a properly functional road, the terrain must often be adjusted. In many situations, geometric design will often involve minimizing the cost of earthwork movement. Earthwork is expressed in units of volumes (cubic meters in metric). Increases in such volumes require additional trucks (or more runs of the same truck), which cost money. Thus, it is important for designers to engineer roads that require very little earthwork.
## Cross Sections and Volume Computation
A Roadway Cross Section on otherwise Level Ground
To determine the amount of earthwork to occur on a given site, one must calculate the volume. For linear facilities, which include highways, railways, runways, etc., volumes can easily be calculated by integrating the areas of the cross sections (slices that go perpendicular to the centerline) for the entire length of the corridor. More simply, several cross sections can be selected along the corridor and an average can be taken for the entire length. Several different procedures exist for calculating areas of earthwork cross sections. In the past, the popular method was to draw cross sections by hand and use a planimeter to measure area. In modern times, computers use a coordinate method to assess earthwork calculations. To perform this task, points with known elevations need to be identified around the cross section. These points are considered in the (X, Y) coordinate plane, where X represents the horizontal axis paralleling the ground and Y represents the vertical axis that is elevation. Area can be computed with the following formula:
$A = |\frac{{1}}{{2}}\sum\limits_{i = 1}^n {X_i(Y_{i+1} - Y_{i-1})}|\,\!$
Where:
• $A\,\!$ = Area of Cross-Section
• $n\,\!$ = Number of Points on Cross Section (Note: n+1 = 1 and 1-1=n, for indexing)
• $X\,\!$ = X-Coordinate
• $Y\,\!$ = Y-Coordinate
With this, earthwork volumes can be calculated. The easiest means to do so would by using the average end area method, where the two end areas are averaged over the entire length between them.
$V = \frac{{A_1 + A_2}}{{2}}L\,\!$
Where:
• $V\,\!$ = Volume
• $A_1\,\!$ = Cross section area of first side
• $A_2\,\!$ = Cross section area of second side
• $L\,\!$ = Length between the two areas
If one end area has a value of zero, the earthwork volume can be considered a pyramid and the correct formula would be:
$V = \frac{{AL}}{{3}}\,\!$
A more accurate formula would the prismoidal formula, which takes out most of the error accrued by the average end area method.
$V_p = \frac{{L(A_1 + 4A_m + A_2)}}{{6}} \,\!$
Where:
• $V_p\,\!$ = Volume given by the prismoidal formula
• $A_m\,\!$ = Area of a plane surface midway between the two cross sections
## Cut and Fill
A Typical Cut/Fill Diagram
Various sections of a roadway design will require bringing in earth. Other sections will require earth to be removed. Earth that is brought in is considered Fill while earth that is removed is considered Cut. Generally, designers generate drawings called Cut and Fill Diagrams, which illustrate the cut or fill present at any given site. This drawing is quite standard, being no more than a graph with site location on the X-axis and fill being the positive range of the Y-axis while cut is the negative range of the Y-axis.
A Typical Mass Diagram (Note: Additional Dirt is Needed in this Example)
## Mass Balance
Using the data for cut and fill, an overall mass balance can be computed. The mass balance represents the total amount of leftover (if positive) or needed (if negative) earth at a given site based on the design up until that point. It is a useful piece of information because it can identify how much remaining or needed earth will be present at the completion of a project, thus allowing designers to calculate how much expense will be incurred to haul out excess dirt or haul in needed additional. Additionally, a mass balance diagram, represented graphically, can aid designers in moving dirt internally to save money.
Similar to the cut and fill diagram, the mass balance diagram is illustrated on two axes. The X-axis represents site location along the roadway corridor and the Y-axis represents the amount of earth, either in excess (positive) or needed (negative).
## Examples
### Example 1: Computing Volume
Problem:
A roadway is to be designed on a level terrain. This roadway is 150 meters in length. Four cross sections have been selected, one at 0 meters, one at 50 meters, one at 100 meters, and one at 150 meters. The cross sections, respectively, have areas of 40 square meters, 42 square meters, 19 square meters, and 34 square meters. What is the volume of earthwork needed along this road?
Solution:
Three sections exist between all of these cross sections. Since none of the sections end with an area of zero, the average end area method can be used. The volumes can be computed for respective sections and then summed together.
Section between 0 and 50 meters:
$V = \frac{{A_1 + A_2}}{{2}}L = \frac{{40 + 42}}{{2}}50 = 2050\ cubic-meters\,\!$
Section between 50 and 100 meters:
$V = \frac{{A_1 + A_2}}{{2}}L = \frac{{42 + 19}}{{2}}50 = 1525\ cubic-meters\,\!$
Section between 100 and 150 meters:
$V = \frac{{A_1 + A_2}}{{2}}L = \frac{{19 + 34}}{{2}}50 = 1325\ cubic-meters\,\!$
Total Volume is found to be:
$2050 + 1525 + 1325 = 4900\ cubic-meters\,\!$
### Example 2: Mass Balance
Problem:
Given the following cut/fill profile for each meter along a 10-meter strip of road built on very, very hilly terrain, estimate the amount of dirt left over or needed for the project.
• 0 Meters: 3 meters of fill
• 1 Meter: 1 meter of fill
• 2 Meters: 2 meters of cut
• 3 Meters: 5 meters of cut
• 4 Meters: 7 meters of cut
• 5 Meters: 8 meters of cut
• 6 Meters: 2 meters of cut
• 7 Meters: 1 meter of fill
• 8 Meters: 3 meters of fill
• 9 Meters: 6 meters of fill
• 10 Meters: 7 meters of fill
Solution:
If 'cut' is considered an excess of available earth and 'fill' is considered a reduction of available earth, the problem becomes one of simple addition and subtraction.
$[(-3) + (-1) + 2 + 5 + 7 + 8 + 2 + (-1) + (-3) + (-6) + (-7)] * 1 m^2 = 3\ cubic-meters\,\!$
3 cubic-meters of dirt remain in excess.
## Thought Question
Problem
If it is found that the mass balance is indeed balanced (end value of zero), does that automatically mean that no dirt transport, either out of or into the site, is needed?
Solution
No. Any soil scientist will eagerly state that dirt type can change with location quite quickly, depending on the region. So, if half a highway cuts from the earth and the other half needs fill, the dirt pulled from the first half cannot be simply dumped into the second half, even if mathematically it balances. If the soil types are different, the exact numbers of volume needed may be different, as different soil types have different properties (settling, water storage, etc.). In the worse case, not consulting a soil scientist could result in your road being washed out!
Homework
## Variables
• $A$ - Area of Cross-Section
• $n$ - Number of Points on Cross Section (Note: n+1 = 1 and 1-1=n, for indexing)
• $X$ - X-Coordinate
• $Y$ - Y-Coordinate
• $V$ - Volume
• $A_1$ - Cross section area of first side
• $A_2$ - Cross section area of second side
• $L$ - Length between the two areas
• $V_p$ - Volume given by the prismoidal formula
• $A_m$ - Area of a plane surface midway between the two cross sections
## Key Terms
• Cut
• Fill
• Mass Balance
• Area
• Volume
• Earthwork
• Prismoidal Volume | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 29, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8374074697494507, "perplexity": 1927.2154653199843}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-35/segments/1440644064362.36/warc/CC-MAIN-20150827025424-00247-ip-10-171-96-226.ec2.internal.warc.gz"} |
http://mathhelpforum.com/trigonometry/84968-exam-question.html | 1. ## Exam Question
In the diagram give, AC = BC = 1, CD = n and angles ABC = $\displaystyle \theta$, BAD = $\displaystyle \beta$.
i) Prove that: tan $\displaystyle \theta$= $\displaystyle \frac{1 - n}{1 + n}$tan$\displaystyle \beta$
ii) What type of triangle is ABD in the case where n= 1?
Could someone please show me how to do this question? I dont get it at all.
2. I've finally solved (i) YAY
But I don't seem to get (ii). Any hints please? | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7145508527755737, "perplexity": 936.4253047407889}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-22/segments/1526794867995.55/warc/CC-MAIN-20180527024953-20180527044953-00382.warc.gz"} |
http://math.stackexchange.com/questions/93721/best-way-to-find-magnitude-and-phase-of-a-specific-frequency-in-an-empirical-tim | # Best way to find magnitude and phase of a specific frequency in an empirical time series…
I've a discrete, univariate time series, and I'm interested in to investigate a specific frequency component.
Assume I'm interested in a frequency with a cycle-time of $f$ samples - and I need to get the best understanding I can of its magnitude and phase at the instant of the most recent sample. As I see it, I need to consider $n.f$ samples - where n is a positive integer... and there's a trade-off: with small n, my estimation of the f-frequency will be most adversely affected by noise (other frequencies - higher and lower); with large $n$, the effects of this noise are reduced but I must settle for the average phase over $n$ cycles - which won't account for changes in phase and magnitude over the $n.f$ duration.
There is, of course, another aspect - if I consider a sliding window of $n.f$ - I should expect it to advance by $2.\pi\over f$ with each new sample - and for any change in magnitude to be proportionally small... assuming my analysis of the frequency $f$ component of the signal is meaningful.
My first idea about establishing the phase and magnitude was to do a bunch of FFTs and discard all but the frequency of interest in each. This, however, seems somewhat wasteful.
Are there any well known techniques for addressing this sort of problem? Should I just run with FFTs - or are there more efficient approaches I might adopt?
- | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8393364548683167, "perplexity": 344.8210587582842}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-27/segments/1435375097512.42/warc/CC-MAIN-20150627031817-00168-ip-10-179-60-89.ec2.internal.warc.gz"} |
https://www.chemicalforums.com/index.php?topic=90203.msg323295 | August 05, 2021, 04:24:16 AM
Forum Rules: Read This Before Posting
### Topic: Precipitate with Si (Read 2095 times)
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#### vanderwaals
• Regular Member
• Posts: 27
• Mole Snacks: +0/-0
##### Precipitate with Si
« on: February 19, 2017, 08:58:06 PM »
Elemental silicon is oxidized by O2 to give a compound
which dissolves in molten Na2CO3. When this solution is
treated with aqueous hydrochloric acid, a precipitate
forms. What is the precipitate?
(A) SiH4 (B) SiCO3 (C) SiO2 (D) SiCl4
The answer is (C). I'm just very confused about what happens here. I thought that after elemental silicon is oxidized (the first step), SiO2 would be produced...but I have no idea if that's correct. I don't know what the reaction with HCl has to do with anything either. Could someone guide me through what happens after each reaction? Thanks in advance!
#### thetada
• Rhyming Chemist
• Full Member
• Posts: 182
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##### Re: Precipitate with Si
« Reply #1 on: February 19, 2017, 09:12:22 PM »
What effect do you think the hydrochloric acid might have on the sodium carbonate?
#### vanderwaals
• Regular Member
• Posts: 27
• Mole Snacks: +0/-0
##### Re: Precipitate with Si
« Reply #2 on: February 19, 2017, 11:22:59 PM »
Well it reacts to form water and carbon dioxide...but I'm not sure how this is related to the precipitate
#### AWK
• Retired Staff
• Sr. Member
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• Gender:
##### Re: Precipitate with Si
« Reply #3 on: February 20, 2017, 01:51:41 AM »
Quote
to give a compound
which dissolves in molten Na2CO3
This is chemical reaction.
See wikipedia: sodium silicate.
AWK
#### thetada
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• Full Member
• Posts: 182
• Mole Snacks: +18/-0
##### Re: Precipitate with Si
« Reply #4 on: February 20, 2017, 04:59:30 PM »
Well it reacts to form water and carbon dioxide...but I'm not sure how this is related to the precipitate
Turns out nothing but it doesn't hurt to consider all possibilities. The question is very misleadingly phrased, it's not dissolving to make a solution, it's reacting to make a new species. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8914713859558105, "perplexity": 15180.159032898264}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-31/segments/1627046155458.35/warc/CC-MAIN-20210805063730-20210805093730-00537.warc.gz"} |
https://www.physicsforums.com/threads/converging-diverging-nozzle.741632/ | # Homework Help: Converging-Diverging Nozzle
1. Mar 5, 2014
### Maylis
1. The problem statement, all variables and given/known data
2. Air flows from a large supply tank in which the pressure is 147 psig and the temperature is 160 F through a converging - diverging nozzle. The velocity at the throat of the nozzle is sonic. A normal shock occurs at a point in the diverging section of the nozzle where the cross-sectional area is 1.44 times the cross-sectional area of the throat.
a) Compute the Mach number, pressure, and temperature just upstream of the shock.
b) Compute the Mach number, pressure, and temperature just downstream of the shock.
2. Relevant equations
3. The attempt at a solution
I thought the slide 9 would be the equation to use for this problem, but if S* is what they mean, that is just the cross sectional area of the throat, right? What is S supposed to be without the Asterisk?
I am not sure how I could determine the mach numbers up and downstream of the shock using any of the equations give in the lecture slides. is Po, To, etc just at the ''back pressure'' (back pressure is the tank pressure, right?)
2. Mar 5, 2014
### SteamKing
Staff Emeritus
We have no idea what 'slide 9' refers to.
3. Mar 5, 2014
### Maylis
My apologies, I intended to post the slides
File size:
380.2 KB
Views:
137
4. Mar 9, 2014
### Maylis
I am just using the equation on the 9th slide. Honestly, I can't really say I understand what the equation means. I know S* is the cross sectional area where the velocity is sonic (the throat), but my best guess is that S is an arbitrary cross section anywhere along the pipe. However, I wonder if it is only for the divergent part of the nozzle?
slide 10 summarizes all the equations, and of course T, P, ρ, etc are probably corresponding with S? It explicitly states T0, P0, etc. are at the reservoir, but doesn't mention what T, P, etc are.
I am uncertain of what it meant by ''just upstream of the shock'' or ''just downsteam'' and how I am supposed to calculate these. Just upstream can be anything upsteam, what are they asking for more precisely?
This table seems to agree with my calculation of the mach number being 1.80
http://www.cchem.berkeley.edu/cbe150a/isentropic_flow.pdf
#### Attached Files:
• ###### 5.2 attempt 1.pdf
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136.1 KB
Views:
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Last edited: Mar 9, 2014 | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9257803559303284, "perplexity": 1201.2411911763252}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-22/segments/1526794865691.44/warc/CC-MAIN-20180523161206-20180523181206-00591.warc.gz"} |
http://chemistry.stackexchange.com/questions/14490/neutralization-reaction | # Neutralization reaction
Question) Complete and balance each of the following molecular equations (in aqueous solution); include phase labels. Then, for each, write the net ionic equation.
(A) $\ce{NH_3 + HNO_3 ->}$
My Attempt: I thought that the acid $\ce{HNO3}$ would just give its hydrogen to $\ce{NH3}$ and make the resulting reaction $\ce{NH_3 + HNO_3 -> HNH_3 + NO_3}$. However the correct answer is $\ce{NH_3 + HNO_3 -> NH_4NO_3}.$
-
1. An acid-base reaction is not the exchange of a hydrogen atom $\ce{H}$. It is the exchange of a hydrogen ion (or proton) $\ce{H+}$. Thus your answer should be: $$\ce{NH3 +HNO3 -> NH4+ + NO3-}$$
2. The given answer combines the two ions produced into a single compound, which is reasonable given that you are not told if the reaction occurs in aqueous solution. $$\ce{NH4+ + NO3- ->NH4NO3}$$ | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.918634295463562, "perplexity": 810.1347082850731}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-42/segments/1414119651455.41/warc/CC-MAIN-20141024030051-00151-ip-10-16-133-185.ec2.internal.warc.gz"} |
https://www.mankier.com/3/gluPartialDisk.3G | # gluPartialDisk.3G - Man Page
draw an arc of a disk
## C Specification
``` GLdouble inner,
GLdouble outer,
GLint slices,
GLint loops,
GLdouble start,
GLdouble sweep )```
## Parameters
inner
Specifies the inner radius of the partial disk (can be 0).
outer
Specifies the outer radius of the partial disk.
slices
Specifies the number of subdivisions around the z axis.
loops
Specifies the number of concentric rings about the origin into which the partial disk is subdivided.
start
Specifies the starting angle, in degrees, of the disk portion.
sweep
Specifies the sweep angle, in degrees, of the disk portion.
## Description
gluPartialDisk renders a partial disk on the $z\text{ }=\text{ }0$ plane. A partial disk is similar to a full disk, except that only the subset of the disk from start through start + sweep is included (where 0 degrees is along the +yaxis, 90 degrees along the +x axis, 180 degrees along the -y axis, and 270 degrees along the -x axis).
The partial disk has a radius of outer, and contains a concentric circular hole with a radius of inner. If inner is 0, then no hole is generated. The partial disk is subdivided around the z axis into slices (like pizza slices), and also about the z axis into rings (as specified by slices and loops, respectively).
With respect to orientation, the +z side of the partial disk is considered to be outside (see gluQuadricOrientation). This means that if the orientation is set to GLU_OUTSIDE, then any normals generated point along the +z axis. Otherwise, they point along the -z axis.
If texturing is turned on (with gluQuadricTexture), texture coordinates are generated linearly such that where $r\text{ }=\text{ }\text{outer}$, the value at (r, 0, 0) is (1.0, 0.5), at (0, r, 0) it is (0.5, 1.0), at (-r, 0, 0) it is (0.0, 0.5), and at (0, -r, 0) it is (0.5, 0.0). | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 2, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8667274713516235, "perplexity": 2595.3958315469613}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-39/segments/1631780057580.39/warc/CC-MAIN-20210924201616-20210924231616-00538.warc.gz"} |
https://xianblog.wordpress.com/2014/12/01/reflections-on-the-probability-space-induced-by-moment-conditions-with-implications-for-bayesian-inference-discussion/?shared=email&msg=fail | ## reflections on the probability space induced by moment conditions with implications for Bayesian Inference [discussion]
[Following my earlier reflections on Ron Gallant’s paper, here is a more condensed set of questions towards my discussion of next Friday.]
“If one specifies a set of moment functions collected together into a vector m(x,θ) of dimension M, regards θ as random and asserts that some transformation Z(x,θ) has distribution ψ then what is required to use this information and then possibly a prior to make valid inference?” (p.4)
The central question in the paper is whether or not given a set of moment equations
$\mathbb{E}[m(X_1,\ldots,X_n,\theta)]=0$
(where both the Xi‘s and θ are random), one can derive a likelihood function and a prior distribution compatible with those. It sounds to me like a highly complex question since it implies the integral equation
$\int_{\Theta\times\mathcal{X}^n} m(x_1,\ldots,x_n,\theta)\,\pi(\theta)f(x_1|\theta)\cdots f(x_n|\theta) \text{d}\theta\text{d}x_1\cdots\text{d}x_n=0$
must have a solution for all n’s. A related question that was also remanent with fiducial distributions is how on Earth (or Middle Earth) the concept of a random theta could arise outside Bayesian analysis. And another one is how could the equations make sense outside the existence of the pair (prior,likelihood). A question that may exhibit my ignorance of structural models. But which may also relate to the inconsistency of Zellner’s (1996) Bayesian method of moments as exposed by Geisser and Seidenfeld (1999).
For instance, the paper starts (why?) with the Fisherian example of the t distribution of
$Z(x,\theta) = \frac{\bar{x}_n-\theta}{s/\sqrt{n}}$
which is truly is a t variable when θ is fixed at the true mean value. Now, if we assume that the joint distribution of the Xi‘s and θ is such that this projection is a t variable, is there any other case than the Dirac mass on θ? For all (large enough) sample sizes n? I cannot tell and the paper does not bring [me] an answer either.
When I look at the analysis made in the abstraction part of the paper, I am puzzled by the starting point (17), where
$p(x|\theta) = \psi(Z(x,\theta))$
since the lhs and rhs operate on different spaces. In Fisher’s example, x is an n-dimensional vector, while Z is unidimensional. If I apply blindly the formula on this example, the t density does not integrate against the Lebesgue measure in the n-dimension Euclidean space… If a change of measure allows for this representation, I do not see so much appeal in using this new measure and anyway wonder in which sense this defines a likelihood function, i.e. the product of n densities of the Xi‘s conditional on θ. To me this is the central issue, which remains unsolved by the paper.
This site uses Akismet to reduce spam. Learn how your comment data is processed. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 4, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9463316202163696, "perplexity": 736.8348942511639}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-29/segments/1593657176116.96/warc/CC-MAIN-20200715230447-20200716020447-00465.warc.gz"} |
https://ask.sagemath.org/questions/8184/revisions/ | # Revision history [back]
### how to properly substitute in a matrix?
Let's consider a modified example from Sage reference manual
f(x,y)=x^2*y+y^2+y
solutions=solve(list(f.diff()),[x,y])
the_solution=solutions[2]
H=f.diff(2); # Hessian matrix
How can i properly substitute the_solution into H?
I have tried:
H(x,y).subs(the_solution) - does not work.
This will work for H(x,y).subs(x==0)
H(x,y).subs_expr(*the_solution) - does not work.
This will work for f(x,y).subs_expr(*the_solution)
2 No.2 Revision kcrisman 11867 ●36 ●121 ●237
### how to properly substitute in a matrix?
Let's consider a modified example from Sage reference manual
f(x,y)=x^2*y+y^2+y
solutions=solve(list(f.diff()),[x,y])
the_solution=solutions[2]
f(x,y)=x^2*y+y^2+y
solutions=solve(list(f.diff()),[x,y])
the_solution=solutions[2]
H=f.diff(2); # Hessian matrixmatrix
How can i properly substitute the_solution into H?
I have tried:
H(x,y).subs(the_solution) - does not work.
This will work for H(x,y).subs(x==0)
H(x,y).subs_expr(*the_solution) - does not work.
This will work for f(x,y).subs_expr(*the_solution) | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.20839492976665497, "perplexity": 10764.262754383388}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-47/segments/1573496668716.69/warc/CC-MAIN-20191116005339-20191116033339-00351.warc.gz"} |
https://deepai.org/publication/taming-the-long-tail-of-deep-probabilistic-forecasting | DeepAI
# Taming the Long Tail of Deep Probabilistic Forecasting
Deep probabilistic forecasting is gaining attention in numerous applications ranging from weather prognosis, through electricity consumption estimation, to autonomous vehicle trajectory prediction. However, existing approaches focus on improvements on the most common scenarios without addressing the performance on rare and difficult cases. In this work, we identify a long tail behavior in the performance of state-of-the-art deep learning methods on probabilistic forecasting. We present two moment-based tailedness measurement concepts to improve performance on the difficult tail examples: Pareto Loss and Kurtosis Loss. Kurtosis loss is a symmetric measurement as the fourth moment about the mean of the loss distribution. Pareto loss is asymmetric measuring right tailedness, modeling the loss using a generalized Pareto distribution (GPD). We demonstrate the performance of our approach on several real-world datasets including time series and spatiotemporal trajectories, achieving significant improvements on the tail examples.
• 2 publications
• 1 publication
• 35 publications
06/21/2021
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Neural forecasting has shown significant improvements in the accuracy of...
## 1 Introduction
Forecasting is one of the most fundamental problems in time series and spatiotemporal data analysis, with broad applications in energy, finance, and transportation. Deep learning models [li2019enhancing, salinas2020deepar, rasul2021autoregressive] have emerged as state-of-the-art approaches for forecasting rich time series and spatiotemporal data. In several forecasting competitions such as M5 forecasting competition [makridakis2020m5], Argoverse motion forecasting challenge [chang2019argoverse], and IARAI Traffic4cast contest [kreil2020surprising]
, almost all the winning solutions are based on deep neural networks.
Despite the encouraging progress, we discover that the forecasting performance of deep learning models has long-tail behavior. That means, a significant amount of samples are very difficult to forecast. Existing works often measure the forecasting performance by averaging across test samples. However, such an average performance measured by root mean square error (RMSE) or mean absolute error (MAE) can be misleading. A low RMSE or MAE may indicate good averaged performance, but it does not prevent the model from behaving disastrously in difficult scenarios.
From a practical perspective, the long-tail behavior in forecasting performance can be alarming. Figure 1 visualizes examples of long-tail behavior for a motion forecasting task. In motion forecasting, the long-tail would correspond to rare events in driving such as turning maneuver and sudden stops. Failure to forecast accurately in these scenarios would pose paramount safety risks in route planning. In electricity forecasting, the tail behavior would occur during short circuits, power outage, grid failures, or sudden behavior changes. Merely focusing on the average performance would ignore the electric load anomalies, significantly increasing the maintenance and operational cost.
Long-tailed learning is an area heavily studied in classification settings focusing on class imbalance. We refer readers to Table 2 in [menon2020long] and the survey paper by [zhang2021deep] for a complete review. Most common approaches to address the long-tail problem include post-hoc normalization, data resampling, loss engineering, and learning class-agnostic representations. However, long-tail learning methods in classification are not directly translatable to forecasting as we do not have a pre-defined class. A recent work by [makansi2021exposing]
propose to use Kalman filter to gauge the difficulty of different forecasting examples but such difficulties may not directly relate to deep neural networks used for the actual forecasting task.
In this paper, we address the long-tail behavior of prediction error for deep probabilistic forecasting. We present two moment-based loss modifications: Kurtosis loss and Pareto loss. Kurtosis is a well studied symmetric measure of tailedness as a scaled fourth moment of the distribution. Pareto loss uses Generalized Pareto Distribution (GPD) to fit the long-tailed error distribution and can also be described as a weighted summation of shifted moments. We investigate these tailedness measurements as regularization and loss weighting approaches for probabilistic forecasting tasks. We demonstrate significantly improved tail performance compared to the base model and the baselines, while achieving better average performance in most settings.
In summary, our contributions include
• We discover long-tail behavior in the forecasting performance of deep probabilistic models.
• We investigate principled approaches to address long-tail behavior and propose two novel methods: Pareto loss and Kurtosis loss.
• We significantly improve the tail performance on four forecasting tasks including two time series and two spatiotemporal trajectory forecasting datasets.
## 2 Related work
Deep probabilistic forecasting. There is a flurry of work on using deep neural networks for probabilistic forecasting. For time series forecasting, a common practice is to combine classic time series models with deep learning, resulting in DeepAR [salinas2020deepar], Deep State Space [rangapuram2018deep], Deep Factors [wang2019deep] and normalizing Kalman Filter [de2020normalizing]. Others introduce normalizing flow [rasul2020multivariate], denoising diffusion [rasul2021autoregressive] and particle filter [pal2021rnn] to deep learning. For trajectory forecasting, the majority of works focus on deterministic prediction. A few recent works propose to approximate the conditional distribution of future trajectories given the past with explicit parameterization [mfp, luo2020probabilistic], CVAE [CVAE, desire, trajectron++] or implicit models such as GAN [socialgan, liu2019naomi]. Nevertheless, most existing works focus on average performance, the issue of long-tail is largely overlooked in the community.
Long-tailed learning.
The main efforts for addressing the long-tail issue in learning revolve around reweighing, resampling, loss function engineering, and two-stage training, but mostly for classification. Rebalancing during training comes either in form of synthetic minority oversampling
[chawla2002smote], oversampling with adversarial examples [Kozerawski_2020_ACCV], inverse class frequency balancing [liu2019large], balancing using effective number of samples [cui2019class], or balance-oriented mixup augmentation [xu2021towards]. Another direction involves post-processing either in form of normalized calibration [pan2021model]
[menon2020long]. An important direction is loss modification approaches such as Focal Loss [lin2017focal], Shrinkage Loss [lu2018deep], and Balanced Meta-Softmax [ren2020balanced]. Others utilize two-stage training [liu2019large, cao2019learning] or separate expert networks [zhou2020bbn, li2020overcoming, wang2020long]. We refer the readers to [zhang2021deep] for an extensive survey. [tang2020long] indicated SGD momentum can contribute to the aggravation of the long-tail problem and suggested de-confounded training to mitigate its effects. [feldman2020does, feldman2020neural] performed theoretical analysis and suggested label memorization in long-tail distribution as a necessity for the network to generalize.
A few were developed for imbalanced regression. Many approaches revolve around modifications of SMOTE such as adapted to regression SMOTER [torgo2013smote], augmented with Gaussian Noise SMOGN [branco2017smogn], or [ribeiro2020imbalanced] work extending for prediction of extremely rare values. [steininger2021density]
proposed DenseWeight, a method based on Kernel Density Estimation for better assessment of the relevance function for sample reweighing.
[yang2021delving] proposed a distribution smoothing over label (LDS) and feature space (FDS) for imbalanced regression. A concurrent work is [makansi2021exposing] where they noticed the long-tail error distribution for trajectory prediction. They used Kalman filter [kalman1960new] performance as a difficulty measure and utilized contrastive learning to alleviate the tail problem. However, the tail of Kalman Filter may differ from that of deep learning models, which we elaborate on in later sections.
## 3 Methodology
We first identify the long-tail phenomena in probabilistic forecasting. Then, we propose two related strategies based on Pareto loss and Kurtosis loss to mitigate the tail issue.
### 3.1 Long-tail in probabilistic forecasting
Given input and output respectively, probabilistic forecasting task aims to predict the conditional distribution of future states given current and past observations as:
p(yt+1,…,yt+h|xt−k,…,,xt) (1)
where is the length of the history and is the prediction horizon. We denote the maximum likelihood probabilistic forecasting model prediction as .
Long tail distribution of data can be seen in numerous real world datasets. This is evident for the four benchmark forecasting datasets (Electricity [Dua:2019], Traffic [Dua:2019], ETH-UCY [pellegrini2009you, lerner2007crowds], and nuScenes [caesar2020nuscenes]) studied in this work. We can see the distribution of ground truth values () for all of them in Figure 2. We use log-log plots to increase the visibility of the long tail behavior present in the data – smaller values (constituting the minority on a linear scale) occur very frequently, while majority of values are very rare (creating the tail). In addition to the long tail data distribution, we also identify the long tail distribution of forecasting error from deep learning models (such as DeepAR [salinas2020deepar], Trajectron++ [salzmann2020trajectron++], and Trajectron++EWTA [makansi2019overcoming]) (as seen in Appendix G).
We hypothesize that long tail behavior in forecasting error distribution originates from the long tail behavior in data distribution, as well as the nature of gradient based deep learning. Therefore, modifying the loss function to account for the shape of the distribution would potentially lead to better tail performance. Next, we present two loss functions based on the moment of the error distribution.
### 3.2 Pareto Loss
Long tail distributions naturally lend themselves to analysis using Extreme Value Theory (EVT). [mcneil1997estimating]
shows that long tail behavior can be modeled as a generalized Pareto distribution (GPD). The probability distribution function (pdf) of the GPD is,
f(ξ,η,μ)(a)=1η(1+ξ(a−μη))−(1ξ+1) (2)
where the parameters are location (), scale () and shape (). The pdf for GPD is defined for when and for when . can be set to 0 without loss of generality as it represents translation along the x axis. We can drop the scaling term
as the pdf will be scaled using a hyperparameter. The simplified pdf is,
f(ξ,η)(a)=(1+ξaη)−(1ξ+1) (3)
The high-level idea of Pareto loss is to fit a GPD to the loss distribution to reprioritize the learning of easy and difficult (tail) examples. Let the loss function used by a given machine learning model be denoted as
. In probabilistic forecasting, a commonly used loss is Negative Log Likelihood (NLL) loss: where is the training example, and the model prediction. As the pdf in Eq.(3) only allows non-negative input, the loss has to be lower-bounded. We propose to use an auxiliary loss to fit the GPD. For NLL which can be unbounded for continuous distributions, the auxiliary loss can simply be Mean Absolute Error (MAE): .
There are two main classes of methods for modifying loss functions to improve tail performance: regularization [ren2020balanced, makansi2021exposing] and re-weighting [lin2017focal, lu2018deep, yang2021delving]. Both classes are characterized by different behavior on tail data [ren2020balanced]. Inspired by these, we propose two variations of the Pareto Loss using the distribution fitted on : Pareto Loss Margin (PLM) and Pareto Loss Weighted (PLW).
PLM is based on the principles of margin-based regularization [ren2020balanced, liu2016large] which assigns larger penalties (margins) to harder examples. For a given hyperparameter , PLM is defined as,
lplm=l+λ∗rplm(^l) (4)
where
rplm(^l)=1−f(ξ,η)(^l) (5)
which uses GPD to calculate the additive margin.
An alternative is to reweigh the loss terms using the loss distribution. For a given hyperparameter , PLW is defined as,
lplw=wplw(^l)∗l (6)
where
wplw(^l)=1−λ∗f(ξ,η)(^l) (7)
which uses GPD to reweigh the loss of each sample.
### 3.3 Kurtosis Loss
Kurtosis measures the tailedness of a distribution as the scaled fourth moment about the mean. To increase the emphasis on tail examples, we use this measure to propose kurtosis loss. For a given hyperparameter and using the same notation as Sec.3.2 kurtosis loss is defined as,
lkurt=l+λ∗rkurt(^l) (8)
where is the contribution of an example to kurtosis for a batch
rkurt(^l)=⎛⎝^l−μ^lσ^l⎞⎠4 (9)
where and
are the mean and standard deviation of the auxiliary loss (
) values for a batch of examples.
We propose to use the auxiliary loss distribution to compute kurtosis, as performance metrics in forecasting tasks frequently involve versions of L1 or L2 distance such as RMSE, MAE, or ADE. The goal is to decrease the long tail for these metrics, which might not correlate well with the base loss . The example in Sec. 3.2 where is NLL loss and is MAE loss illustrates this requirement well.
Kurtosis loss and pareto loss are related approaches to handling long tail behavior. Pareto Loss is a weighted sum of moments about while kurtosis loss is the fourth moment about the mean. Let and , then the Taylor expansion for the GPD pdf from Eq.(3) is,
(1+b)c=1+cb+c(c−1)2!b2+c(c−1)(c−2)3!b3+⋯ (10)
For or equivalently or
, the coefficients are positive for even moments and negative for odd moments. Even moments are always symmetric and positive, while odd moments are positive only for right-tailed distributions. Since we use the negative of the pdf, it yields an asymmetric measure of the right tailedness of a value in the distribution.
Kurtosis loss uses the fourth moment about the distribution mean. This is a symmetric and positive measure, but in the context of right tailed distributions, kurtosis serves as a good measure of the long tailedness of the distribution. GPD and kurtosis are visualised in Appendix F
## 4 Experiments
We evaluate our methods on two probabilistic forecasting tasks: time series forecasting and trajectory prediction.
### 4.1 Setup
#### Datasets.
For time series forecasting, we use electricity and traffic datasets from the UCI ML repository [Dua:2019] used in [salinas2020deepar] as benchmarks. We also generate three synthetic 1D time series datasets, Sine, Gaussian and Pareto, to further our understanding of long tail behavior.
For trajectory prediction, we use two benchmark datasets: a pedestrian trajectory dataset ETH-UCY (which is a combination of ETH [pellegrini2009you] and UCY [lerner2007crowds] datasets) and a vehicle trajectory dataset nuScenes [caesar2020nuscenes]. Details regarding the datasets are available in Appendix A.
#### Baselines.
We compare with the following baselines representing SoTA in long tail mitigation for different tasks:
• [itemsep=1mm, topsep=0mm]
• Contrastive Loss: [makansi2021exposing] uses contrastive loss as a regularizer to group examples together based on Kalman filter prediction errors.
• Focal Loss: [lin2017focal] uses L1 loss to reweigh loss terms.
• Shrinkage Loss: [lu2018deep] uses a sigmoid-based function to reweigh loss terms.
• Label Distribution Smoothing (LDS): [yang2021delving] uses symmetric kernel to smooth the label distribution and use its inverse to reweigh loss terms.
Focal Loss, Shrinkage Loss, and LDS were originally proposed for classification and/or regression and required adaptation in order to be applicable to the forecasting task. For details on baseline adaptation, please see Appendix B.
#### Evaluation Metrics.
We use two common metrics for the evaluation of trajectory prediction models: Average Displacement Error (ADE), which is the average L2 distance between total predicted trajectory and ground truth, and Final Displacement Error (FDE) which is the L2 distance for the final timestep. For time series forecasting, we use Normalized Deviation (ND) and Normalized Root Mean Squared Error (NRMSE).
Apart from the above-mentioned average performance metrics, we introduce metrics to capture performance on the tail. To measure the performance at tail of the distribution, we propose to adapt the Value-at-Risk (VaR Eq. (11)) metric:
VaRα(E)=inf{e∈E:P(E≥e)≤1−α} (11)
VaR at level is the smallest error
such that the probability of observing error larger than
is smaller than , where is the error distribution. This evaluates to the quantile of the error distribution. We propose to measure VaR at three different levels: , , and .
In addition, we use skew, kurtosis, and max error to further assess the tail performance. Skew and Kurtosis as metrics are meaningful only when looked at in conjunction with the mean. A distribution with a higher mean and lower skew and kurtosis does not imply a less severe tail.
### 4.2 Synthetic Dataset Experiments
In order to better understand the long tail error distribution, we perform experiments on three synthetic datasets. The task is to forecast 8 steps ahead given a history of 8 time steps. We use AutoRegression (AR) and DeepAR [salinas2020deepar] as forecasting models to perform this task. The top row in Figure 3 shows that among the datasets, only Gaussian and Pareto show tail behavior in the data distribution. Pareto dataset in particular is the only one to display long tail behavior. AR and DeepAR have different error distribution across the datasets. Based on these results, we make the following hypotheses for the sources of long-tailedness.
Source 1: Long Tail in Data. The data distributions for Gaussian and Pareto datasets have similar tail behavior to the error distribution for both models, AR and DeepAR. This indicates that the long tail in data is a likely cause of long tail behavior in error. This connection is also well established as class imbalance for classification tasks [van2018inaturalist, liu2019large].
Source 2: Deep Learning Model. The results on the Sine dataset illustrate that even in the absence of long tail in the data, we can have long tail in the error distribution. The AR model, however, does not show long tail behavior for error. This indicates that the observed long tail behavior in error for DeepAR is model induced. We hypothesize that this is caused by DeepAR overfitting to simpler examples due to the nature of gradient based learning. Further results and analysis on these datasets can be found in Appendix H.
The difference between AR and DeepAR error distributions also suggests that assuming tail overlap between deep learning and non-deep learning methods (such as Kalman filter used by [makansi2021exposing]) might not generalize well.
### 4.3 Real-World Experiments
#### Time Series Forecasting
We present average and tail metrics on ND and NRMSE for the time series forecasting task on electricity and traffic datasets in Tables 1 and 2 respectively. We use DeepAR [salinas2020deepar], one of the SoTA in probabilistic time series forecasting, as the base model. The task for both datasets is to use a 1-week history (168 hours) to forecast for 1 day (24 hours) at an hourly frequency. DeepAR exhibits long tail behavior in error on both datasets (refer Appendix G). The tail of the error distribution is significantly longer for the electricity dataset as compared to the traffic dataset.
#### Trajectory Forecasting
We present experimental results on ETH-UCY and nuScenes datasets in Tables 3 and 4 respectively. Following [salzmann2020trajectron++] and [makansi2021exposing] we calculate model performance based on the best out of 20 guesses. On both datasets we compare our approaches with current SoTA long-tail baseline methods using Trajectron++EWTA [makansi2021exposing] as a base model due to its SoTA average performance on these datasets. We include the Trajectron++ [salzmann2020trajectron++] results for reference as the previous state-of-the-art method to add a meaningful comparison to the magnitude of performance change obtained by each long tail method.
On performing a comparative analysis of tail lengths between datasets, we notice that trajectory datasets manifest shorter tails compared to 1D time series datasets. Our Pareto approaches work better on longer tails and for this reason we augment weight and margin for PLM and PLW with an additional Mean Squared Error weight term to internally elongate the tail during the training process.
### 4.4 Results Analysis
As shown in Tables 3 and 4, our proposed approaches, kurtosis loss and PLM, are the only methods improving on tail metrics across all tasks while maintaining the average performance of the base model. Our tasks differ in representation (1D, 2D), severity of long-tail, base model loss function (GaussNLL, EWTA) and prediction horizon. This indicates that our methods generalize to diverse situations better than existing long-tail methods.
#### Long-tailedness across datasets
Using Eq. (12) as an indicative measure of the long-tailedness in error distribution, we establish the datasets as ETH-UCY, nuScenes, electricity, and traffic in long-tailedness for the base model (Details in Appendix E). We notice the connections between long-tailedness of the dataset and the performance of different methods.
TailLength=VaR95Mean+VaR98VaR95+VaR99VaR98+MaxVaR99 (12)
#### Re-weighting vs Regularization.
As mentioned in Section 3.2, we can categorize loss modifying methods into two classes: re-weighting (focal loss, shrinkage loss, LDS and PLW) and regularization (contrastive loss, PLM and kurtosis loss). Re-weighting multiplies the loss for more difficult examples with higher weights. Regularization adds higher regularization values for examples with higher loss.
We notice that re-weighting methods perform worse as the long-tailedness increases. In scenarios with longer tails, the weights of tail samples can be very high. Over-emphasizing tail examples hampers the learning for other samples. Shrinkage loss with a bounded weight limits this issue but fails to show tail improvements in longer tail scenarios. PLW is the best re-weighting method on most datasets, likely due to its bounded weights. Inconsistency in average performance is likely due to re-weighting nature of the loss which limits its applicability.
In contrast, regularization methods perform consistently across all tasks both on the tail and average metrics. The additive nature of regularization limits the adverse impact tail samples can have on the learning. This enables these methods to handle different long-tailednesses without degrading the average performance.
#### PLM vs Kurtosis loss.
Kurtosis loss generally performs better on extreme tail metrics, and Max. The bi-quadratic behavior of kurtosis puts higher emphasis on far-tail samples. Moreover, the magnitude of kurtosis varies significantly for different distributions, making the choice of hyperparameter (See Eq.(8)) critical. Further analysis on the same is available in Appendix D.
PLM is the most consistent method across all tasks improving on both tail and average metrics. As noted by [mcneil1997estimating] GPD is well suited to model long tail error distributions. PLM rewards examples moving away from the tail towards the mean with significantly lower margin values. PLM margin values saturate beyond a point in the tail providing similar improvements for subsequent tail samples. Visualization of PLM predictions for difficult tail examples can be seen in Fig. 4.
Kurtosis is sensitive to extreme samples in the tail, while PLM treats most samples in the tail similarly. This manifests in performance as kurtosis loss performing better on and Max, and PLM performing better on and .
This provides guidance on the choice of method as per the objective. Kurtosis Loss can improve the performance in worst case scenarios more significantly. PLM provides less drastic changes to the most extreme values, but it works more effectively throughout the entire distribution.
#### Tail error and long-term forecasting
Based on the trajectory forecasting results in Tables 3 and 4 we can see that error reduction for tail samples is more visible in FDE than ADE. This indicates that the magnitude of the observed error increases with the prediction horizon. The error accumulates through prediction steps making far-future predictions inherently more difficult. Larger improvements in the FDE indicate that both Kurtosis and Pareto loss ensure that high tail errors (stemming mostly from large, far-future prediction errors measured by FDE) are decreased.
The inadvertent direction of research in the forecasting domain is aiming at increasing the prediction horizon with high accuracy predictions. As we can see in Fig. 5, the effect of the tail examples is more pronounced with longer prediction horizons. Thus, methods addressing the tail performance will be necessary in order to ensure the practical applicability and reliability of future, long-term prediction.
## 5 Conclusion
We address the long-tail problem in deep probabilistic forecasting. We propose Pareto loss (Margin and Weighted) and Kurtosis loss, two novel moment-based loss function approaches increasing emphasis on learning tail examples. We demonstrate their practical effects on two spatiotemporal trajectory datasets and two time series datasets. Our methods achieve significant improvements on tail examples over existing baselines without degrading average performance. Both proposed losses can be integrated with existing approaches in deep probabilistic forecasting to improve their performance on difficult and challenging scenarios.
Future directions include more principled ways to tune hyperparameters, new approaches to mitigate long tail for long-term forecasting and application to more complex tasks like video prediction. Based on our observations, we suggest evaluating additional tail performance metrics apart from average performance in machine learning task to identify potential long tail issues across different tasks and domains.
## Acknowledgments
This work was supported in part by U.S. Department Of Energy, Office of Science, U. S. Army Research Office under Grant W911NF-20-1-0334, Facebook Data Science Award, Google Faculty Award, and NSF Grant #2037745.
## Appendix A Dataset description
The ETH-UCY dataset consists of five subdatasets, each with Bird’s-Eye-Views: ETH, Hotel, Univ, Zara1, and Zara2. As is common in the literature [makansi2021exposing, salzmann2020trajectron++] we present macro-averaged 5-fold cross-validation results in our experiment section. The nuScenes dataset includes 1000 scenes of 20 second length for vehicle trajectories recorded in Boston and Singapore.
The electricity dataset contains electricity consumption data for 370 homes over the period of Jan 1st, 2011 to Dec 31st, 2014 at a sampling interval of 15 minutes. We use the data from Jan 1st, 2011 to Aug 31st, 2011 for training and data from Sep 1st, 2011 to Sep 7th, 2011 for testing. The traffic dataset consists of occupancy values recorded by 963 sensors at a sampling interval of 10 minutes ranging from Jan 1st, 2008 to Mar 30th, 2009. We use data from Jan 1st, 2008 to Jun 15th, 2008 for training and data from Jun 16th, 2008 to Jul 15th, 2008 for testing. Both time series datasets are downsampled to 1 hour for generating examples.
The synthetic datasets are generated as 100 different time series consisting of 960 time steps. Each time series in the Sine dataset is generated using a random offset and a random frequency
both selected from a uniform distribution
. Then the time series is where
is the index of the time step. Gaussian and Pareto datasets are generated as order 1 lag autoregressive time series with randomly sampled Gaussian and Pareto noise respectively. Gaussian noise is sampled from a Gaussian distribution with mean 1 and standard deviation 1. Pareto noise is randomly sampled from a Pareto distribution with shape 10 and scaling 1.
#### Time Series forecasting
DeepAR uses Gaussian Negative Log Likelihood as the loss which is unbounded. Due to this many baseline methods need to be adapted in order to be usable. For the same reason, we also need an auxiliary loss (). We use MAE loss to fit the GPD, calculate kurtosis, and to calculate the weight terms for Focal and Shrinkage loss. For LDS we treat all labels across time steps as a part of a single distribution. Additionally, to avoid extremely high weights () in LDS due to the nature of long tail we ensure a minimum probability of for all labels.
#### Trajectory forecasting
We adapt Focal Loss and Shrinkage Loss to use EWTA loss [makansi2019overcoming] in order to be compatible with Trajectron++EWTA base model. LDS was originally proposed for a regression task and we adapt it to the trajectory prediction task in the same way as for the time series task. We use MAE to fit the GPD, due to the Evolving property of EWTA loss.
## Appendix C Implementation details
#### Time Series forecasting
We use the DeepAR implementation from https://github.com/zhykoties/TimeSeries as the base code to run all time series experiments. The original code is an AWS API and not publicly available. The implementation of contrastive loss is taken directly from the source code of [makansi2021exposing].
#### Trajectory forecasting
For all tested base methods in the trajectory forecasting experiments (Trajectron++ [salzmann2020trajectron++] and Trajectron++EWTA [makansi2021exposing]) we have used the original implementations provided by the original authors of each method. The implementation of contrastive loss is taken directly from the source code of [makansi2021exposing].
The experiments have been conducted on a machine with 7 RTX 2080 Ti GPUs.
## Appendix D Hyperparameter Tuning
We observe during our experiments that the performance of kurtosis loss is highly dependent on the hyperparameter (See Eq. (8)). Results for different values of on the electricity dataset for kurtosis are shown in Table5. We also show the variation of ND and NRMSE with the hyperparameter value in Figure 6. We can see that there is an optimal value of the hyperparameter and the approach performs worse with higher and lower values.
For both ETH-UCY and nuScenes datasets we have used for Kurtosis loss, and for PLM and PLW. For both electricity and traffic datasets, we use for PLM, for PLW and for Kurtosis loss.
## Appendix E Long tail severity
In Table 6 we present the numerical values representing the approximate long-tailedness for each of the datasets. Larger value indicates a longer tail.
## Appendix F Pareto and Kurtosis
Figure 7 illustrates different GPDs for different shape parameter values. Higher shape value models more severe tail behavior.
## Appendix G Long tail error distribution
In Fig. 8 we can see log-log plots of the error distributions of base model for each of the datasets. We can see each distribution exhibits a long tail behavior.
## Appendix H Synthetic datasets
We present complete results of our experiments on the synthetic datasets in Table 7. We ran our methods, kurtosis loss, and PLM on these datasets as well. Both our methods show significant tail improvements over the base model across all datasets. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8359820246696472, "perplexity": 1894.6577434388735}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2023-06/segments/1674764499890.39/warc/CC-MAIN-20230131190543-20230131220543-00015.warc.gz"} |
https://socratic.org/questions/how-do-you-write-a-polynomial-function-of-least-degree-and-leading-coefficient-1-15 | Precalculus
Topics
# How do you write a polynomial function of least degree and leading coefficient 1 when the zeros are -5, 2, -2?
Feb 28, 2017
${x}^{3} + 5 {x}^{2} - 4 x - 20 = 0$
#### Explanation:
$\text{ if the zeros are" -5,2,-2, " we write down the corresponding factors and multiply them}$
zeros
$x = - 5 \implies \left(x + 5\right) = 0$
$x = 2 \implies \left(x - 2\right) = 0$
$x = - 2 \implies \left(x + 2\right) = 0$
the polynomial is:
$\left(x + 5\right) \left(x - 2\right) \left(x + 2\right) = 0$
multiplying out.
$\left(x + 5\right) \left({x}^{2} - 4\right) = 0 \text{ (difference of squares)}$
${x}^{3} - 4 x + 5 {x}^{2} - 20 = 0$
tidying up
${x}^{3} + 5 {x}^{2} - 4 x - 20 = 0$
##### Impact of this question
56 views around the world | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 9, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.189529150724411, "perplexity": 3400.7456105026977}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-09/segments/1550249530087.75/warc/CC-MAIN-20190223183059-20190223205059-00306.warc.gz"} |
http://compgroups.net/comp.text.tex/pantone-colors-with-pdflatex-and-xcolor/1936657 | COMPGROUPS.NET | Post | Groups | Users | Stream | Browse | About | |
### Pantone colors with pdflatex and xcolor?
• Email
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Is this even possible?
The printing house, who is going to print a book I've helped typeset,
can apparently only handle Pantone colors. At the moment I'm using rgb
So what are my options in this case?
--
/daleif (remove RTFSIGNATURE from email address)
Memoir and mh bundle maintainer
LaTeX FAQ: http://www.tex.ac.uk/faq
LaTeX book: http://www.imf.au.dk/system/latex/bog/ (in Danish)
Remember to post minimal examples, see URL below
http://www.minimalbeispiel.de/mini-en.html
0
Reply daleif1329 (544) 6/6/2011 1:23:31 PM
See related articles to this posting
On Jun 6, 6:23=A0pm, Lars Madsen <[email protected]> wrote:
> Is this even possible?
>
> The printing house, who is going to print a book I've helped typeset,
> can apparently only handle Pantone colors. At the moment I'm using rgb
>
> So what are my options in this case?
>
> --
>
> /daleif (remove RTFSIGNATURE from email address)
>
> Memoir and mh bundle maintainer
> LaTeX FAQ: =A0 =A0 =A0http://www.tex.ac.uk/faq
> LaTeX book: =A0 =A0http://www.imf.au.dk/system/latex/bog/=A0(in Danish)
> Remember to post minimal examples, see URL belowhttp://www.minimalbeispie=
l.de/mini-en.html
Please have a look into spotcolor.sty
Regards,
Saravanan,M.
0
On 06/06/11 14:23, Lars Madsen wrote:
> Is this even possible?
>
> The printing house, who is going to print a book I've helped typeset,
> can apparently only handle Pantone colors. At the moment I'm using rgb
>
> So what are my options in this case?
You should probably be using CMYK definitions if you are setting for
print. Pantone provides CMYK settings for its colours, but you have to
///Peter
0
Reply peter2615 (652) 6/7/2011 6:36:58 PM
Le 06/06/2011 15:23, Lars Madsen a �crit :
> Is this even possible?
>
> The printing house, who is going to print a book I've helped typeset,
> can apparently only handle Pantone colors. At the moment I'm using rgb
>
> So what are my options in this case?
>
This may be of interest:
http://www.zedimage.com/pms-cmyk-hex.php
0
Reply gouailles (1755) 6/7/2011 7:09:23 PM
Le 07/06/2011 21:09, GL a �crit :
> Le 06/06/2011 15:23, Lars Madsen a �crit :
>> Is this even possible?
>>
>> The printing house, who is going to print a book I've helped typeset,
>> can apparently only handle Pantone colors. At the moment I'm using rgb
>>
>> So what are my options in this case?
>>
>
> This may be of interest:
>
> http://www.zedimage.com/pms-cmyk-hex.php
There is also this one for named colors :
nice palette :-) probably incomplete but nice !
0
Reply gouailles (1755) 6/7/2011 7:17:24 PM
On 7 juin, 15:09, GL <[email protected]> wrote:
> Le 06/06/2011 15:23, Lars Madsen a =E9crit :
>
> > Is this even possible?
>
> > The printing house, who is going to print a book I've helped typeset,
> > can apparently only handle Pantone colors. At the moment I'm using rgb
>
> > So what are my options in this case?
>
> This may be of interest:
>
> http://www.zedimage.com/pms-cmyk-hex.php
http://www.zedimage.com/pms-cmyk-hex.php
0
Le 19/07/2011 21:40, Premiers a �crit :
> On 7 juin, 15:09, GL<[email protected]> wrote:
>> Le 06/06/2011 15:23, Lars Madsen a �crit :
>>
>>> Is this even possible?
>>
>>> The printing house, who is going to print a book I've helped typeset,
>>> can apparently only handle Pantone colors. At the moment I'm using rgb
>>
>>> So what are my options in this case?
>>
>> This may be of interest:
>>
>> http://www.zedimage.com/pms-cmyk-hex.php
>
>
>
>
> http://www.zedimage.com/pms-cmyk-hex.php
Yes ? And this one is nice too:
since it defines some named colors (easier to memorize/use/read in the
source) However I didn't test them and i'm not sure of the result in a
pdf. But it could be a starting point to add a "pantone" option to
xcolor... may be underground (i heard Pantone colors to be "protected",
even if such "protection" sounds not legal in Europe...)
0
Reply gouailles (1755) 7/19/2011 7:49:58 PM
>
> Yes ? And this one is nice too:
>
>
> since it defines some named colors (easier to memorize/use/read in the
> source) However I didn't test them and i'm not sure of the result in a
> pdf. But it could be a starting point to add a "pantone" option to
> xcolor... may be underground (i heard Pantone colors to be "protected",
> even if such "protection" sounds not legal in Europe...)
>
>
>
true, but there are far fewer of them.....
0
Reply pinkse (345) 7/19/2011 8:01:55 PM
Le 19/07/2011 22:01, Joris Pinkse a �crit :
>
>>
>> Yes ? And this one is nice too:
>>
>>
>> since it defines some named colors (easier to memorize/use/read in the
>> source) However I didn't test them and i'm not sure of the result in a
>> pdf. But it could be a starting point to add a "pantone" option to
>> xcolor... may be underground (i heard Pantone colors to be "protected",
>> even if such "protection" sounds not legal in Europe...)
>>
>>
>>
>
> true, but there are far fewer of them.....
From the palette, would it be possible to set up a function that give
the correspondance between cmyk and PMS (Pantone Matching System) ?
Not so easy at first glance...
However, it could be quite easy to extract the CMYK values from the HTML
file in order to provide a PMS option for xcolor in about one hour for
a waked guy ;-)
0
Reply gouailles (1755) 7/19/2011 8:49:01 PM
Le 19/07/2011 22:01, Joris Pinkse a �crit :
>
>>
>> Yes ? And this one is nice too:
>>
>>
>> since it defines some named colors (easier to memorize/use/read in the
>> source) However I didn't test them and i'm not sure of the result in a
>> pdf. But it could be a starting point to add a "pantone" option to
>> xcolor... may be underground (i heard Pantone colors to be "protected",
>> even if such "protection" sounds not legal in Europe...)
>>
>>
>>
>
> true, but there are far fewer of them.....
Now you should compare ;-)
\documentclass [a4paper]{article}
\usepackage [cmyk]{xcolor}
\pdfpageattr{/Group <</S /Transparency /I true /CS /DeviceRGB>>}
\begin{document}
\def\colornameprefix{XC@}
\preparecolorset{cmyk}{}{}{%
PMS100,0,0,0.510000,0;%
PMS101,0,0,0.790000,0;%
PMS102,0,0.010000,0.950000,0;%
PMS103,0,0.030000,1,0.180000;%
PMS104,0,0.030000,1,0.300000;%
PMS105,0,0.030000,1,0.500000;%
PMS106,0,0.020000,0.690000,0;%
PMS107,0,0.040000,0.790000,0;%
PMS108,0,0.060000,0.950000,0;%
PMS109,0,0.100000,1,0;%
PMS110,0,0.120000,1,0.070000;%
PMS111,0,0.110000,1,0.270000;%
PMS112,0,0.100000,1,0.380000;%
PMS113,0,0.070000,0.660000,0;%
PMS114,0,0.080000,0.730000,0;%
PMS115,0,0.090000,0.800000,0;%
PMS116,0,0.160000,1,0;%
PMS117,0,0.180000,1,0.150000;%
PMS118,0,0.180000,1,0.270000;%
PMS119,0,0.120000,1,0.490000;%
PMS120,0,0.090000,0.580000,0;%
PMS1205,0,0.050000,0.310000,0;%
PMS121,0,0.110000,0.690000,0;%
PMS1215,0,0.090000,0.450000,0;%
PMS122,0,0.170000,0.800000,0;%
PMS1225,0,0.170000,0.620000,0;%
PMS123,0,0.240000,0.940000,0;%
PMS1235,0,0.290000,0.910000,0;%
PMS124,0,0.280000,1,0.060000;%
PMS1245,0,0.280000,1,0.180000;%
PMS125,0,0.260000,1,0.260000;%
PMS1255,0,0.270000,1,0.340000;%
PMS126,0,0.250000,1,0.370000;%
PMS1265,0,0.270000,1,0.510000;%
PMS127,0,0.070000,0.500000,0;%
PMS128,0,0.110000,0.650000,0;%
PMS129,0,0.160000,0.770000,0;%
PMS130,0,0.300000,1,0;%
PMS131,0,0.320000,1,0.090000;%
PMS132,0,0.280000,1,0.300000;%
PMS133,0,0.200000,1,0.560000;%
PMS134,0,0.110000,0.450000,0;%
PMS1345,0,0.140000,0.470000,0;%
PMS135,0,0.190000,0.600000,0;%
PMS1355,0,0.200000,0.560000,0;%
PMS136,0,0.270000,0.760000,0;%
PMS1365,0,0.290000,0.720000,0;%
PMS137,0,0.350000,0.900000,0;%
PMS1375,0,0.400000,0.900000,0;%
PMS138,0,0.420000,1,0.010000;%
PMS1385,0,0.440000,1,0.070000;%
PMS139,0,0.370000,1,0.230000;%
PMS1395,0,0.410000,1,0.370000;%
PMS140,0,0.270000,1,0.540000;%
PMS1405,0,0.360000,1,0.630000;%
PMS141,0,0.190000,0.510000,0;%
PMS142,0,0.280000,0.760000,0;%
PMS143,0,0.350000,0.850000,0;%
PMS144,0,0.480000,1,0;%
PMS145,0,0.470000,1,0.080000;%
PMS146,0,0.430000,1,0.330000;%
PMS147,0,0.280000,1,0.560000;%
PMS148,0,0.160000,0.370000,0;%
PMS1485,0,0.270000,0.540000,0;%
PMS149,0,0.230000,0.470000,0;%
PMS1495,0,0.330000,0.670000,0;%
PMS150,0,0.350000,0.700000,0;%
PMS1505,0,0.420000,0.770000,0;%
PMS151,0,0.480000,0.950000,0;%
PMS152,0,0.510000,1,0.010000;%
PMS1525,0,0.580000,1,0.100000;%
PMS153,0,0.460000,1,0.180000;%
PMS1535,0,0.530000,1,0.380000;%
PMS154,0,0.460000,1,0.340000;%
PMS1545,0,0.530000,1,0.720000;%
PMS155,0,0.120000,0.280000,0;%
PMS1555,0,0.220000,0.340000,0;%
PMS156,0,0.220000,0.420000,0;%
PMS1565,0,0.340000,0.490000,0;%
PMS157,0,0.430000,0.700000,0;%
PMS1575,0,0.450000,0.720000,0;%
PMS158,0,0.610000,0.970000,0;%
PMS1585,0,0.560000,0.900000,0;%
PMS159,0,0.660000,1,0.070000;%
PMS1595,0,0.590000,1,0.050000;%
PMS160,0,0.620000,1,0.320000;%
PMS1605,0,0.560000,1,0.300000;%
PMS161,0,0.520000,1,0.640000;%
PMS1615,0,0.560000,1,0.430000;%
PMS162,0,0.150000,0.220000,0;%
PMS1625,0,0.310000,0.370000,0;%
PMS163,0,0.310000,0.440000,0;%
PMS1635,0,0.390000,0.480000,0;%
PMS164,0,0.460000,0.730000,0;%
PMS1645,0,0.490000,0.660000,0;%
PMS165,0,0.590000,0.960000,0;%
PMS1655,0,0.630000,0.910000,0;%
PMS166,0,0.640000,1,0;%
PMS1665,0,0.680000,1,0;%
PMS167,0,0.600000,1,0.170000;%
PMS1675,0,0.670000,1,0.280000;%
PMS168,0,0.570000,1,0.590000;%
PMS1685,0,0.680000,1,0.440000;%
PMS169,0,0.200000,0.200000,0;%
PMS170,0,0.400000,0.440000,0;%
PMS171,0,0.530000,0.680000,0;%
PMS172,0,0.660000,0.880000,0;%
PMS173,0,0.690000,1,0.040000;%
PMS174,0,0.700000,1,0.360000;%
PMS175,0,0.650000,1,0.600000;%
PMS176,0,0.250000,0.180000,0;%
PMS1765,0,0.380000,0.210000,0;%
PMS1767,0,0.270000,0.120000,0;%
PMS177,0,0.450000,0.400000,0;%
PMS1775,0,0.470000,0.290000,0;%
PMS1777,0,0.580000,0.360000,0;%
PMS178,0,0.590000,0.560000,0;%
PMS1785,0,0.670000,0.500000,0;%
PMS1787,0,0.760000,0.600000,0;%
PMS1788,0,0.840000,0.880000,0;%
PMS179,0,0.790000,1,0;%
PMS1795,0,0.940000,1,0;%
PMS1797,0,1,0.990000,0.040000;%
PMS180,0,0.790000,1,0.110000;%
PMS1805,0,0.910000,1,0.230000;%
PMS1807,0,1,0.960000,0.280000;%
PMS181,0,0.740000,1,0.470000;%
PMS1815,0,0.900000,1,0.510000;%
PMS1817,0,0.900000,1,0.660000;%
PMS182,0,0.260000,0.100000,0;%
PMS183,0,0.460000,0.210000,0;%
PMS184,0,0.680000,0.410000,0;%
PMS185,0,0.910000,0.760000,0;%
PMS186,0,1,0.810000,0.040000;%
PMS187,0,1,0.790000,0.200000;%
PMS188,0,0.970000,1,0.500000;%
PMS189,0,0.370000,0.100000,0;%
PMS1895,0,0.280000,0.070000,0;%
PMS190,0,0.550000,0.220000,0;%
PMS1905,0,0.410000,0.090000,0;%
PMS191,0,0.760000,0.380000,0;%
PMS1915,0,0.710000,0.200000,0;%
PMS192,0,1,0.680000,0;%
PMS1925,0,1,0.550000,0;%
PMS193,0,1,0.660000,0.130000;%
PMS1935,0,1,0.570000,0.050000;%
PMS194,0,1,0.640000,0.330000;%
PMS1945,0,1,0.560000,0.190000;%
PMS195,0,1,0.600000,0.550000;%
PMS1955,0,1,0.600000,0.370000;%
PMS196,0,0.250000,0.040000,0;%
PMS197,0,0.450000,0.100000,0;%
PMS198,0,0.780000,0.330000,0;%
PMS199,0,1,0.620000,0;%
PMS200,0,1,0.630000,0.120000;%
PMS201,0,1,0.630000,0.290000;%
PMS202,0,1,0.610000,0.430000;%
PMS203,0,0.340000,0.030000,0;%
PMS204,0,0.580000,0.030000,0;%
PMS205,0,0.840000,0.090000,0;%
PMS206,0,1,0.380000,0.030000;%
PMS207,0,1,0.430000,0.190000;%
PMS208,0,1,0.360000,0.370000;%
PMS209,0,1,0.340000,0.530000;%
PMS210,0,0.390000,0.060000,0;%
PMS211,0,0.550000,0.080000,0;%
PMS212,0,0.720000,0.110000,0;%
PMS213,0,0.950000,0.270000,0;%
PMS214,0,1,0.340000,0.080000;%
PMS215,0,1,0.350000,0.270000;%
PMS216,0,0.950000,0.400000,0.490000;%
PMS217,0,0.280000,0,0;%
PMS218,0.020000,0.610000,0,0;%
PMS219,0.010000,0.880000,0,0;%
PMS220,0,1,0.130000,0.170000;%
PMS221,0,1,0.150000,0.300000;%
PMS222,0,1,0.100000,0.590000;%
PMS223,0,0.460000,0,0;%
PMS224,0.010000,0.630000,0,0;%
PMS225,0.010000,0.830000,0,0;%
PMS226,0,1,0,0;%
PMS227,0,1,0.070000,0.190000;%
PMS228,0,1,0.040000,0.410000;%
PMS229,0,1,0.150000,0.600000;%
PMS230,0,0.340000,0,0;%
PMS231,0.010000,0.520000,0,0;%
PMS232,0.030000,0.670000,0,0;%
PMS233,0.110000,1,0,0;%
PMS234,0.060000,1,0,0.260000;%
PMS235,0.050000,1,0,0.400000;%
PMS236,0.010000,0.300000,0,0;%
PMS2365,0.020000,0.270000,0,0;%
PMS237,0.030000,0.490000,0,0;%
PMS2375,0.100000,0.570000,0,0;%
PMS238,0.060000,0.630000,0,0;%
PMS2385,0.190000,0.790000,0,0;%
PMS239,0.110000,0.790000,0,0;%
PMS2395,0.270000,0.950000,0,0;%
PMS240,0.180000,0.940000,0,0;%
PMS2405,0.340000,1,0,0;%
PMS241,0.270000,1,0,0.020000;%
PMS2415,0.330000,1,0,0.080000;%
PMS242,0.100000,1,0,0.490000;%
PMS2425,0.370000,1,0,0.260000;%
PMS243,0.050000,0.290000,0,0;%
PMS244,0.090000,0.380000,0,0;%
PMS245,0.140000,0.530000,0,0;%
PMS246,0.290000,0.900000,0,0;%
PMS247,0.360000,1,0,0;%
PMS248,0.400000,1,0,0.020000;%
PMS249,0.400000,1,0,0.280000;%
PMS250,0.050000,0.180000,0,0;%
PMS251,0.130000,0.390000,0,0;%
PMS252,0.240000,0.560000,0,0;%
PMS253,0.430000,0.950000,0,0;%
PMS254,0.500000,1,0,0;%
PMS255,0.510000,1,0,0.250000;%
PMS256,0.070000,0.200000,0,0;%
PMS2562,0.190000,0.350000,0,0;%
PMS2563,0.220000,0.330000,0,0;%
PMS2567,0.290000,0.360000,0,0;%
PMS257,0.140000,0.340000,0,0;%
PMS2572,0.300000,0.470000,0,0;%
PMS2573,0.300000,0.430000,0,0;%
PMS2577,0.400000,0.450000,0,0;%
PMS258,0.430000,0.760000,0,0;%
PMS2582,0.460000,0.720000,0,0;%
PMS2583,0.460000,0.630000,0,0;%
PMS2587,0.590000,0.660000,0,0;%
PMS259,0.560000,1,0,0.150000;%
PMS2592,0.600000,0.900000,0,0;%
PMS2593,0.610000,0.890000,0,0;%
PMS2597,0.850000,1,0,0;%
PMS260,0.520000,1,0,0.260000;%
PMS2602,0.630000,1,0,0.030000;%
PMS2603,0.690000,1,0,0.020000;%
PMS2607,0.810000,1,0,0.070000;%
PMS261,0.480000,1,0,0.400000;%
PMS2612,0.640000,1,0,0.140000;%
PMS2613,0.630000,1,0,0.150000;%
PMS2617,0.790000,1,0,0.150000;%
PMS262,0.450000,1,0,0.550000;%
PMS2622,0.580000,1,0,0.440000;%
PMS2623,0.590000,1,0,0.320000;%
PMS2627,0.770000,1,0,0.310000;%
PMS263,0.100000,0.140000,0,0;%
PMS2635,0.280000,0.270000,0,0;%
PMS264,0.260000,0.280000,0,0;%
PMS2645,0.400000,0.360000,0,0;%
PMS265,0.540000,0.560000,0,0;%
PMS2655,0.540000,0.490000,0,0;%
PMS266,0.790000,0.900000,0,0;%
PMS2665,0.620000,0.600000,0,0;%
PMS267,0.890000,1,0,0;%
PMS268,0.820000,1,0,0.120000;%
PMS2685,0.960000,1,0,0.100000;%
PMS269,0.780000,1,0,0.330000;%
PMS2695,0.910000,1,0,0.490000;%
PMS270,0.310000,0.270000,0,0;%
PMS2705,0.400000,0.300000,0,0;%
PMS2706,0.190000,0.090000,0,0;%
PMS2707,0.170000,0.060000,0,0;%
PMS2708,0.260000,0.100000,0,0;%
PMS271,0.430000,0.370000,0,0;%
PMS2715,0.570000,0.450000,0,0;%
PMS2716,0.450000,0.290000,0,0;%
PMS2717,0.290000,0.120000,0,0;%
PMS2718,0.670000,0.410000,0,0;%
PMS272,0.580000,0.480000,0,0;%
PMS2725,0.770000,0.680000,0,0;%
PMS2726,0.790000,0.660000,0,0;%
PMS2727,0.710000,0.420000,0,0;%
PMS2728,0.960000,0.690000,0,0;%
PMS273,1,0.960000,0,0.080000;%
PMS2735,1,0.950000,0,0;%
PMS2736,1,0.910000,0,0;%
PMS2738,1,0.870000,0,0.020000;%
PMS274,1,1,0,0.280000;%
PMS2745,1,0.950000,0,0.150000;%
PMS2746,1,0.920000,0,0.100000;%
PMS2747,1,0.860000,0,0.150000;%
PMS2748,1,0.880000,0,0.150000;%
PMS275,0.980000,1,0,0.430000;%
PMS2755,1,0.970000,0,0.300000;%
PMS2756,1,0.940000,0,0.290000;%
PMS2757,1,0.820000,0,0.300000;%
PMS2758,1,0.800000,0,0.260000;%
PMS276,0.980000,1,0,0.550000;%
PMS2765,1,0.970000,0,0.450000;%
PMS2766,1,0.940000,0,0.470000;%
PMS2767,1,0.780000,0,0.540000;%
PMS2768,1,0.780000,0,0.440000;%
PMS277,0.270000,0.070000,0,0;%
PMS278,0.390000,0.140000,0,0;%
PMS279,0.680000,0.340000,0,0;%
PMS280,1,0.720000,0,0.180000;%
PMS281,1,0.720000,0,0.320000;%
PMS282,1,0.680000,0,0.540000;%
PMS283,0.350000,0.090000,0,0;%
PMS284,0.550000,0.190000,0,0;%
PMS285,0.890000,0.430000,0,0;%
PMS286,1,0.660000,0,0.020000;%
PMS287,1,0.680000,0,0.120000;%
PMS288,1,0.670000,0,0.230000;%
PMS289,1,0.660000,0,0.580000;%
PMS290,0.250000,0.020000,0,0;%
PMS2905,0.410000,0.020000,0,0;%
PMS291,0.330000,0.030000,0,0;%
PMS2915,0.590000,0.070000,0,0;%
PMS292,0.490000,0.110000,0,0;%
PMS2925,0.850000,0.240000,0,0;%
PMS293,1,0.570000,0,0.020000;%
PMS2935,1,0.460000,0,0;%
PMS294,1,0.580000,0,0.210000;%
PMS2945,1,0.450000,0,0.140000;%
PMS295,1,0.570000,0,0.370000;%
PMS2955,1,0.450000,0,0.370000;%
PMS296,1,0.460000,0,0.700000;%
PMS2965,1,0.380000,0,0.640000;%
PMS297,0.490000,0.010000,0,0;%
PMS2975,0.300000,0,0.050000,0;%
PMS298,0.690000,0.070000,0,0;%
PMS2985,0.590000,0,0.060000,0;%
PMS299,0.850000,0.190000,0,0;%
PMS2995,0.900000,0.110000,0,0;%
PMS300,1,0.440000,0,0;%
PMS3005,1,0.360000,0,0.020000;%
PMS301,1,0.450000,0,0.180000;%
PMS3015,1,0.330000,0,0.200000;%
PMS302,1,0.250000,0,0.500000;%
PMS3025,1,0.170000,0,0.510000;%
PMS303,1,0.110000,0,0.740000;%
PMS3035,1,0,0.050000,0.720000;%
PMS304,0.300000,0,0.080000,0;%
PMS305,0.510000,0,0.090000,0;%
PMS306,0.750000,0,0.070000,0;%
PMS307,1,0.160000,0,0.270000;%
PMS308,1,0.050000,0,0.470000;%
PMS309,1,0,0.090000,0.720000;%
PMS310,0.430000,0,0.100000,0;%
PMS3105,0.430000,0,0.120000,0;%
PMS311,0.630000,0,0.120000,0;%
PMS3115,0.630000,0,0.180000,0;%
PMS312,0.960000,0,0.110000,0;%
PMS3125,0.830000,0,0.210000,0;%
PMS313,1,0,0.080000,0.130000;%
PMS3135,1,0,0.160000,0.090000;%
PMS314,1,0,0.090000,0.300000;%
PMS3145,1,0,0.190000,0.230000;%
PMS315,1,0,0.120000,0.430000;%
PMS3155,1,0,0.240000,0.380000;%
PMS316,1,0,0.270000,0.680000;%
PMS3165,1,0,0.280000,0.650000;%
PMS317,0.180000,0,0.080000,0;%
PMS318,0.380000,0,0.150000,0;%
PMS319,0.520000,0,0.190000,0;%
PMS320,1,0,0.310000,0.070000;%
PMS321,1,0,0.310000,0.230000;%
PMS322,1,0,0.330000,0.350000;%
PMS323,1,0,0.380000,0.470000;%
PMS324,0.280000,0,0.120000,0;%
PMS3242,0.370000,0,0.180000,0;%
PMS3245,0.340000,0,0.190000,0;%
PMS3248,0.430000,0,0.240000,0;%
PMS325,0.560000,0,0.260000,0;%
PMS3252,0.470000,0,0.240000,0;%
PMS3255,0.490000,0,0.280000,0;%
PMS3258,0.590000,0,0.330000,0;%
PMS326,0.870000,0,0.380000,0;%
PMS3262,0.710000,0,0.330000,0;%
PMS3265,0.690000,0,0.370000,0;%
PMS3268,0.900000,0,0.490000,0;%
PMS327,1,0,0.440000,0.170000;%
PMS3272,1,0,0.440000,0;%
PMS3275,0.950000,0,0.470000,0;%
PMS3278,1,0,0.550000,0.050000;%
PMS328,1,0,0.450000,0.320000;%
PMS3282,1,0,0.460000,0.150000;%
PMS3285,1,0,0.500000,0.070000;%
PMS3288,1,0,0.540000,0.200000;%
PMS329,1,0,0.460000,0.460000;%
PMS3292,1,0,0.490000,0.460000;%
PMS3295,1,0,0.530000,0.210000;%
PMS3298,1,0,0.570000,0.420000;%
PMS330,1,0,0.480000,0.600000;%
PMS3302,1,0,0.540000,0.690000;%
PMS3305,1,0,0.610000,0.610000;%
PMS3308,1,0,0.600000,0.720000;%
PMS331,0.240000,0,0.160000,0;%
PMS332,0.300000,0,0.200000,0;%
PMS333,0.430000,0,0.270000,0;%
PMS334,1,0,0.600000,0.030000;%
PMS335,1,0,0.650000,0.300000;%
PMS336,1,0,0.670000,0.470000;%
PMS337,0.310000,0,0.200000,0;%
PMS3375,0.350000,0,0.250000,0;%
PMS338,0.470000,0,0.320000,0;%
PMS3385,0.450000,0,0.330000,0;%
PMS339,0.840000,0,0.560000,0;%
PMS3395,0.610000,0,0.450000,0;%
PMS340,1,0,0.660000,0.090000;%
PMS3405,0.850000,0,0.650000,0;%
PMS341,1,0,0.670000,0.290000;%
PMS3415,1,0,0.770000,0.220000;%
PMS342,1,0,0.710000,0.430000;%
PMS3425,1,0,0.780000,0.420000;%
PMS343,0.980000,0,0.720000,0.610000;%
PMS3435,1,0,0.810000,0.660000;%
PMS344,0.270000,0,0.230000,0;%
PMS345,0.380000,0,0.320000,0;%
PMS346,0.550000,0,0.470000,0;%
PMS347,1,0,0.860000,0.030000;%
PMS348,1,0,0.850000,0.240000;%
PMS349,1,0,0.910000,0.420000;%
PMS350,0.790000,0,1,0.750000;%
PMS351,0.170000,0,0.160000,0;%
PMS352,0.270000,0,0.250000,0;%
PMS353,0.380000,0,0.360000,0;%
PMS354,0.800000,0,0.900000,0;%
PMS355,0.940000,0,1,0;%
PMS356,0.950000,0,1,0.270000;%
PMS357,0.800000,0,1,0.560000;%
PMS358,0.270000,0,0.380000,0;%
PMS359,0.360000,0,0.490000,0;%
PMS360,0.580000,0,0.800000,0;%
PMS361,0.690000,0,1,0;%
PMS362,0.700000,0,1,0.090000;%
PMS363,0.680000,0,1,0.240000;%
PMS364,0.650000,0,1,0.420000;%
PMS365,0.120000,0,0.290000,0;%
PMS366,0.200000,0,0.440000,0;%
PMS367,0.320000,0,0.590000,0;%
PMS368,0.570000,0,1,0;%
PMS369,0.590000,0,1,0.070000;%
PMS370,0.560000,0,1,0.270000;%
PMS371,0.430000,0,1,0.560000;%
PMS372,0.100000,0,0.330000,0;%
PMS373,0.160000,0,0.460000,0;%
PMS374,0.240000,0,0.570000,0;%
PMS375,0.410000,0,0.780000,0;%
PMS376,0.520000,0,1,0.050000;%
PMS377,0.450000,0,1,0.240000;%
PMS378,0.340000,0,1,0.600000;%
PMS379,0.090000,0,0.580000,0;%
PMS380,0.130000,0,0.720000,0;%
PMS381,0.200000,0,0.910000,0;%
PMS382,0.290000,0,1,0;%
PMS383,0.200000,0,1,0.190000;%
PMS384,0.180000,0,1,0.310000;%
PMS385,0.030000,0,1,0.580000;%
PMS386,0.060000,0,0.560000,0;%
PMS387,0.100000,0,0.740000,0;%
PMS388,0.140000,0,0.790000,0;%
PMS389,0.200000,0,0.850000,0;%
PMS390,0.220000,0,1,0.080000;%
PMS391,0.130000,0,1,0.330000;%
PMS392,0.070000,0,1,0.490000;%
PMS393,0.030000,0,0.550000,0;%
PMS3935,0.010000,0,0.680000,0;%
PMS394,0.060000,0,0.760000,0;%
PMS3945,0.030000,0,0.850000,0;%
PMS395,0.080000,0,0.850000,0;%
PMS3955,0.060000,0,1,0;%
PMS396,0.110000,0,0.940000,0;%
PMS3965,0.080000,0,1,0;%
PMS397,0.100000,0,1,0.110000;%
PMS3975,0,0,1,0.290000;%
PMS398,0.070000,0,1,0.280000;%
PMS3985,0,0.030000,1,0.410000;%
PMS399,0,0,1,0.430000;%
PMS3995,0,0.030000,1,0.640000;%
PMS400,0,0.030000,0.060000,0.160000;%
PMS401,0,0.050000,0.110000,0.230000;%
PMS402,0,0.060000,0.140000,0.310000;%
PMS403,0,0.070000,0.170000,0.430000;%
PMS404,0,0.080000,0.220000,0.560000;%
PMS405,0,0.100000,0.330000,0.720000;%
PMS406,0,0.050000,0.060000,0.160000;%
PMS407,0,0.080000,0.090000,0.260000;%
PMS408,0,0.100000,0.110000,0.340000;%
PMS409,0,0.130000,0.150000,0.450000;%
PMS410,0,0.180000,0.210000,0.560000;%
PMS411,0,0.270000,0.360000,0.720000;%
PMS412,0,0.300000,0.660000,0.980000;%
PMS413,0,0,0.090000,0.200000;%
PMS414,0,0,0.100000,0.300000;%
PMS415,0,0,0.120000,0.410000;%
PMS416,0,0,0.160000,0.500000;%
PMS417,0.010000,0,0.250000,0.650000;%
PMS418,0.030000,0,0.310000,0.750000;%
PMS419,0.290000,0,0.360000,1;%
PMS420,0,0,0,0.150000;%
PMS421,0,0,0,0.260000;%
PMS422,0,0,0,0.330000;%
PMS423,0,0,0,0.440000;%
PMS424,0,0,0,0.610000;%
PMS425,0,0,0,0.770000;%
PMS426,0,0,0,1;%
PMS427,0,0,0,0.110000;%
PMS428,0.020000,0,0,0.180000;%
PMS429,0.030000,0,0,0.320000;%
PMS430,0.050000,0,0,0.450000;%
PMS431,0.110000,0.010000,0,0.640000;%
PMS432,0.230000,0.020000,0,0.770000;%
PMS433,0.330000,0.030000,0,0.950000;%
PMS434,0.070000,0.100000,0.090000,0;%
PMS435,0.130000,0.160000,0.140000,0;%
PMS436,0.240000,0.250000,0.250000,0;%
PMS437,0.460000,0.450000,0.460000,0;%
PMS438,0.750000,0.700000,1,0.100000;%
PMS439,0.800000,0.750000,1,0.200000;%
PMS440,0.820000,0.780000,1,0.300000;%
PMS441,0.060000,0,0.070000,0.090000;%
PMS442,0.080000,0,0.090000,0.190000;%
PMS443,0.120000,0,0.120000,0.300000;%
PMS444,0.150000,0,0.150000,0.420000;%
PMS445,0.200000,0,0.200000,0.650000;%
PMS446,0.210000,0,0.230000,0.750000;%
PMS447,0.160000,0,0.310000,0.820000;%
PMS448,0.750000,0.650000,1,0.300000;%
PMS4485,0,0.260000,1,0.690000;%
PMS449,0.700000,0.600000,1,0.200000;%
PMS4495,0,0.200000,0.950000,0.460000;%
PMS450,0.650000,0.550000,1,0.100000;%
PMS4505,0,0.150000,0.780000,0.360000;%
PMS451,0.330000,0.290000,0.550000,0;%
PMS4515,0,0.090000,0.500000,0.240000;%
PMS452,0.240000,0.190000,0.390000,0;%
PMS4525,0,0.070000,0.390000,0.170000;%
PMS453,0.140000,0.110000,0.250000,0;%
PMS4535,0,0.040000,0.300000,0.110000;%
PMS454,0.090000,0.070000,0.160000,0;%
PMS4545,0,0.030000,0.190000,0.060000;%
PMS455,0,0.170000,1,0.650000;%
PMS456,0,0.150000,1,0.430000;%
PMS457,0,0.150000,1,0.280000;%
PMS458,0.100000,0.100000,0.730000,0;%
PMS459,0.060000,0.070000,0.550000,0;%
PMS460,0.040000,0.050000,0.440000,0;%
PMS461,0.030000,0.030000,0.350000,0;%
PMS462,0.500000,0.700000,1,0.500000;%
PMS4625,0,0.600000,1,0.790000;%
PMS463,0.300000,0.600000,1,0.400000;%
PMS4635,0,0.480000,0.960000,0.440000;%
PMS464,0.100000,0.500000,1,0.350000;%
PMS4645,0,0.370000,0.680000,0.280000;%
PMS465,0.200000,0.320000,0.580000,0;%
PMS4655,0,0.260000,0.450000,0.180000;%
PMS466,0.120000,0.220000,0.430000,0;%
PMS4665,0,0.180000,0.320000,0.100000;%
PMS467,0.090000,0.150000,0.340000,0;%
PMS4675,0,0.110000,0.210000,0.060000;%
PMS468,0.060000,0.090000,0.230000,0;%
PMS4685,0,0.070000,0.140000,0.040000;%
PMS469,0,0.650000,1,0.710000;%
PMS4695,0,0.810000,1,0.740000;%
PMS470,0,0.580000,1,0.330000;%
PMS4705,0,0.620000,0.710000,0.490000;%
PMS471,0,0.590000,1,0.180000;%
PMS4715,0,0.420000,0.450000,0.340000;%
PMS472,0,0.340000,0.520000,0;%
PMS4725,0,0.320000,0.350000,0.250000;%
PMS473,0,0.230000,0.360000,0;%
PMS4735,0,0.220000,0.230000,0.150000;%
PMS474,0,0.150000,0.260000,0;%
PMS4745,0,0.170000,0.180000,0.100000;%
PMS475,0,0.110000,0.200000,0;%
PMS4755,0,0.100000,0.120000,0.060000;%
PMS476,0.600000,0.800000,1,0.450000;%
PMS477,0.500000,0.850000,1,0.380000;%
PMS478,0.400000,0.900000,1,0.300000;%
PMS479,0.310000,0.480000,0.550000,0;%
PMS480,0.150000,0.290000,0.310000,0;%
PMS481,0.090000,0.190000,0.210000,0;%
PMS482,0.050000,0.120000,0.130000,0;%
PMS483,0,0.930000,1,0.600000;%
PMS484,0,0.950000,1,0.290000;%
PMS485,0,0.950000,1,0;%
PMS486,0,0.470000,0.410000,0;%
PMS487,0,0.350000,0.280000,0;%
PMS488,0,0.260000,0.190000,0;%
PMS489,0,0.150000,0.110000,0;%
PMS490,0,0.740000,1,0.720000;%
PMS491,0,0.790000,1,0.520000;%
PMS492,0,0.770000,1,0.420000;%
PMS493,0,0.460000,0.230000,0.050000;%
PMS494,0,0.330000,0.130000,0;%
PMS495,0,0.240000,0.110000,0;%
PMS496,0,0.160000,0.090000,0;%
PMS497,0,0.700000,1,0.780000;%
PMS4975,0,0.730000,1,0.800000;%
PMS498,0,0.640000,1,0.600000;%
PMS4985,0,0.620000,0.510000,0.480000;%
PMS499,0,0.630000,1,0.480000;%
PMS4995,0,0.480000,0.380000,0.340000;%
PMS500,0,0.380000,0.210000,0.110000;%
PMS5005,0,0.380000,0.270000,0.230000;%
PMS501,0,0.270000,0.130000,0.030000;%
PMS5015,0,0.250000,0.150000,0.110000;%
PMS502,0,0.180000,0.100000,0.010000;%
PMS5025,0,0.180000,0.120000,0.070000;%
PMS503,0,0.110000,0.080000,0;%
PMS5035,0,0.100000,0.090000,0.030000;%
PMS504,0.700000,1,1,0.350000;%
PMS505,0.500000,1,1,0.250000;%
PMS506,0.450000,1,1,0.150000;%
PMS507,0.130000,0.490000,0.230000,0;%
PMS508,0.050000,0.360000,0.110000,0;%
PMS509,0,0.240000,0.070000,0;%
PMS510,0,0.170000,0.060000,0;%
PMS511,0.700000,1,0.500000,0.200000;%
PMS5115,0.800000,1,0.700000,0.150000;%
PMS512,0.600000,1,0.150000,0.050000;%
PMS5125,0.650000,0.860000,0.490000,0;%
PMS513,0.460000,0.880000,0,0;%
PMS5135,0.490000,0.660000,0.280000,0;%
PMS514,0.150000,0.500000,0,0;%
PMS5145,0.300000,0.450000,0.120000,0;%
PMS515,0.070000,0.380000,0,0;%
PMS5155,0.170000,0.300000,0.080000,0;%
PMS516,0.030000,0.270000,0,0;%
PMS5165,0.090000,0.190000,0.050000,0;%
PMS517,0,0.180000,0,0;%
PMS5175,0.050000,0.120000,0.030000,0;%
PMS518,0.800000,1,0.600000,0.100000;%
PMS5185,0.880000,1,0.850000,0.100000;%
PMS519,0.720000,1,0.350000,0.050000;%
PMS5195,0.750000,0.950000,0.680000,0.050000;%
PMS520,0.640000,1,0.120000,0;%
PMS5205,0.520000,0.630000,0.480000,0;%
PMS521,0.270000,0.470000,0,0;%
PMS5215,0.290000,0.380000,0.240000,0;%
PMS522,0.170000,0.370000,0,0;%
PMS5225,0.170000,0.270000,0.150000,0;%
PMS523,0.100000,0.260000,0,0;%
PMS5235,0.100000,0.170000,0.100000,0;%
PMS524,0.060000,0.150000,0,0;%
PMS5245,0.060000,0.100000,0.070000,0;%
PMS525,0.840000,1,0.450000,0.050000;%
PMS5255,0.830000,0.850000,0,0.700000;%
PMS526,0.770000,1,0.070000,0;%
PMS5265,0.770000,0.730000,0,0.460000;%
PMS527,0.730000,1,0,0;%
PMS5275,0.670000,0.570000,0,0.340000;%
PMS528,0.410000,0.550000,0,0;%
PMS5285,0.420000,0.350000,0,0.230000;%
PMS529,0.260000,0.400000,0,0;%
PMS5295,0.270000,0.220000,0,0.100000;%
PMS530,0.180000,0.310000,0,0;%
PMS5305,0.160000,0.130000,0,0.070000;%
PMS531,0.100000,0.200000,0,0;%
PMS5315,0.060000,0.060000,0,0.050000;%
PMS532,1,0.880000,0.700000,0.180000;%
PMS533,1,0.850000,0.460000,0.110000;%
PMS534,1,0.820000,0.300000,0.050000;%
PMS535,0.420000,0.300000,0.070000,0;%
PMS536,0.310000,0.220000,0.050000,0;%
PMS537,0.220000,0.140000,0.030000,0;%
PMS538,0.130000,0.090000,0.020000,0;%
PMS539,1,0.490000,0,0.700000;%
PMS5395,1,0.440000,0,0.760000;%
PMS540,1,0.550000,0,0.550000;%
PMS5405,0.580000,0.170000,0,0.460000;%
PMS541,1,0.570000,0,0.380000;%
PMS5415,0.400000,0.080000,0,0.410000;%
PMS542,0.620000,0.220000,0,0.030000;%
PMS5425,0.300000,0.040000,0,0.320000;%
PMS543,0.410000,0.110000,0,0;%
PMS5435,0.130000,0.030000,0,0.170000;%
PMS544,0.300000,0.060000,0,0;%
PMS5445,0.080000,0.010000,0,0.130000;%
PMS545,0.220000,0.030000,0,0;%
PMS5455,0.060000,0,0,0.090000;%
PMS546,0.950000,0.090000,0,0.830000;%
PMS5463,1,0,0.180000,0.830000;%
PMS5467,1,0,0.300000,0.950000;%
PMS547,1,0.190000,0,0.750000;%
PMS5473,0.820000,0,0.280000,0.520000;%
PMS5477,0.560000,0,0.270000,0.740000;%
PMS548,1,0.240000,0,0.640000;%
PMS5483,0.620000,0,0.210000,0.310000;%
PMS5487,0.360000,0,0.170000,0.560000;%
PMS549,0.540000,0.070000,0,0.270000;%
PMS5493,0.430000,0,0.140000,0.210000;%
PMS5497,0.180000,0,0.090000,0.380000;%
PMS550,0.390000,0.040000,0,0.210000;%
PMS5503,0.290000,0,0.100000,0.140000;%
PMS5507,0.110000,0,0.070000,0.290000;%
PMS551,0.270000,0.030000,0,0.130000;%
PMS5513,0.180000,0,0.070000,0.050000;%
PMS5517,0.090000,0,0.060000,0.180000;%
PMS552,0.150000,0,0,0.090000;%
PMS5523,0.110000,0,0.050000,0.030000;%
PMS5527,0.060000,0,0.040000,0.110000;%
PMS553,0.600000,0,0.510000,0.800000;%
PMS5535,0.660000,0,0.570000,0.820000;%
PMS554,0.800000,0,0.600000,0.670000;%
PMS5545,0.590000,0,0.500000,0.520000;%
PMS555,0.790000,0,0.560000,0.560000;%
PMS5555,0.430000,0,0.340000,0.380000;%
PMS556,0.450000,0,0.310000,0.270000;%
PMS5565,0.300000,0,0.240000,0.260000;%
PMS557,0.300000,0,0.200000,0.150000;%
PMS5575,0.200000,0,0.160000,0.170000;%
PMS558,0.200000,0,0.130000,0.090000;%
PMS5585,0.120000,0,0.110000,0.100000;%
PMS559,0.140000,0,0.100000,0.060000;%
PMS5595,0.070000,0,0.080000,0.070000;%
PMS560,0.800000,0,0.630000,0.750000;%
PMS5605,0.650000,0,0.560000,0.940000;%
PMS561,0.850000,0,0.540000,0.520000;%
PMS5615,0.440000,0,0.470000,0.680000;%
PMS562,0.850000,0,0.500000,0.310000;%
PMS5625,0.280000,0,0.300000,0.510000;%
PMS563,0.520000,0,0.320000,0.010000;%
PMS5635,0.160000,0,0.180000,0.360000;%
PMS564,0.370000,0,0.200000,0;%
PMS5645,0.090000,0,0.130000,0.250000;%
PMS565,0.230000,0,0.130000,0;%
PMS5655,0.060000,0,0.090000,0.180000;%
PMS566,0.140000,0,0.090000,0;%
PMS5665,0.050000,0,0.070000,0.100000;%
PMS567,0.820000,0,0.640000,0.700000;%
PMS568,0.880000,0,0.570000,0.360000;%
PMS569,0.980000,0,0.570000,0.170000;%
PMS570,0.480000,0,0.290000,0;%
PMS571,0.320000,0,0.190000,0;%
PMS572,0.230000,0,0.140000,0;%
PMS573,0.140000,0,0.090000,0;%
PMS574,0.340000,0,0.810000,0.710000;%
PMS5743,0.330000,0,0.850000,0.820000;%
PMS5747,0.320000,0,1,0.790000;%
PMS575,0.480000,0,1,0.530000;%
PMS5753,0.250000,0,0.810000,0.670000;%
PMS5757,0.270000,0,0.950000,0.550000;%
PMS576,0.490000,0,1,0.390000;%
PMS5763,0.160000,0,0.740000,0.570000;%
PMS5767,0.150000,0,0.680000,0.390000;%
PMS577,0.240000,0,0.460000,0.100000;%
PMS5773,0.090000,0,0.430000,0.380000;%
PMS5777,0.100000,0,0.490000,0.280000;%
PMS578,0.200000,0,0.400000,0.060000;%
PMS5783,0.060000,0,0.280000,0.270000;%
PMS5787,0.070000,0,0.310000,0.130000;%
PMS579,0.170000,0,0.340000,0.030000;%
PMS5793,0.040000,0,0.210000,0.180000;%
PMS5797,0.050000,0,0.240000,0.090000;%
PMS580,0.120000,0,0.260000,0.020000;%
PMS5803,0.020000,0,0.120000,0.110000;%
PMS5807,0.030000,0,0.140000,0.060000;%
PMS581,0.020000,0,1,0.720000;%
PMS5815,0,0,0.910000,0.790000;%
PMS582,0.130000,0,1,0.460000;%
PMS5825,0,0.020000,0.870000,0.590000;%
PMS583,0.230000,0,1,0.170000;%
PMS5835,0,0.020000,0.670000,0.400000;%
PMS584,0.120000,0,0.790000,0.060000;%
PMS5845,0,0.010000,0.470000,0.300000;%
PMS585,0.110000,0,0.660000,0.020000;%
PMS5855,0,0,0.310000,0.180000;%
PMS586,0.090000,0,0.530000,0;%
PMS5865,0,0,0.250000,0.130000;%
PMS587,0.050000,0,0.400000,0;%
PMS5875,0,0,0.180000,0.080000;%
PMS600,0,0,0.290000,0;%
PMS601,0,0,0.400000,0;%
PMS602,0,0,0.510000,0;%
PMS603,0,0,0.690000,0.010000;%
PMS604,0,0,0.880000,0.030000;%
PMS605,0,0.020000,1,0.070000;%
PMS606,0,0.040000,1,0.120000;%
PMS607,0,0,0.180000,0.010000;%
PMS608,0,0,0.320000,0.020000;%
PMS609,0,0,0.460000,0.040000;%
PMS610,0,0,0.580000,0.060000;%
PMS611,0,0.010000,0.920000,0.110000;%
PMS612,0,0.020000,1,0.200000;%
PMS613,0,0.040000,1,0.300000;%
PMS614,0,0,0.200000,0.040000;%
PMS615,0,0.010000,0.270000,0.060000;%
PMS616,0,0.020000,0.350000,0.090000;%
PMS617,0,0.020000,0.480000,0.170000;%
PMS618,0,0.030000,0.870000,0.300000;%
PMS619,0,0.040000,1,0.430000;%
PMS620,0,0.050000,1,0.530000;%
PMS621,0.130000,0,0.100000,0.020000;%
PMS622,0.240000,0,0.190000,0.040000;%
PMS623,0.320000,0,0.240000,0.100000;%
PMS624,0.440000,0,0.350000,0.200000;%
PMS625,0.560000,0,0.440000,0.330000;%
PMS626,0.760000,0,0.640000,0.630000;%
PMS627,0.900000,0,0.760000,0.840000;%
PMS628,0.190000,0,0.060000,0;%
PMS629,0.340000,0,0.090000,0;%
PMS630,0.470000,0,0.110000,0;%
PMS631,0.670000,0,0.120000,0.020000;%
PMS632,0.920000,0,0.150000,0.050000;%
PMS633,1,0,0.100000,0.250000;%
PMS634,1,0,0.090000,0.400000;%
PMS635,0.320000,0,0.080000,0;%
PMS636,0.450000,0,0.090000,0;%
PMS637,0.550000,0,0.090000,0;%
PMS638,0.830000,0,0.100000,0;%
PMS639,1,0,0.050000,0.050000;%
PMS640,1,0,0,0.220000;%
PMS641,1,0.040000,0,0.300000;%
PMS642,0.160000,0.040000,0,0.020000;%
PMS643,0.250000,0.070000,0,0.040000;%
PMS644,0.420000,0.150000,0,0.060000;%
PMS645,0.570000,0.280000,0,0.090000;%
PMS646,0.690000,0.340000,0,0.110000;%
PMS647,1,0.560000,0,0.230000;%
PMS648,1,0.620000,0,0.540000;%
PMS649,0.140000,0.060000,0,0.010000;%
PMS650,0.240000,0.090000,0,0.020000;%
PMS651,0.380000,0.180000,0,0.060000;%
PMS652,0.600000,0.340000,0,0.100000;%
PMS653,1,0.620000,0,0.200000;%
PMS654,1,0.640000,0,0.380000;%
PMS655,1,0.650000,0,0.520000;%
PMS656,0.140000,0.040000,0,0;%
PMS657,0.240000,0.080000,0,0;%
PMS658,0.410000,0.200000,0,0;%
PMS659,0.640000,0.350000,0,0;%
PMS660,0.900000,0.570000,0,0;%
PMS661,1,0.690000,0,0.090000;%
PMS662,1,0.720000,0,0.180000;%
PMS663,0.070000,0.060000,0,0;%
PMS664,0.110000,0.090000,0,0;%
PMS665,0.200000,0.170000,0,0.020000;%
PMS666,0.310000,0.300000,0,0.070000;%
PMS667,0.520000,0.490000,0,0.140000;%
PMS668,0.650000,0.640000,0,0.300000;%
PMS669,0.760000,0.780000,0,0.470000;%
PMS670,0,0.130000,0,0;%
PMS671,0.010000,0.200000,0,0;%
PMS672,0.030000,0.340000,0,0;%
PMS673,0.060000,0.490000,0,0;%
PMS674,0.090000,0.670000,0,0;%
PMS675,0.170000,1,0,0.030000;%
PMS676,0.060000,1,0,0.220000;%
PMS677,0.020000,0.130000,0,0;%
PMS678,0.030000,0.210000,0,0;%
PMS679,0.050000,0.270000,0,0;%
PMS680,0.100000,0.430000,0,0.020000;%
PMS681,0.210000,0.610000,0,0.040000;%
PMS682,0.250000,0.790000,0,0.120000;%
PMS683,0.110000,1,0,0.430000;%
PMS684,0,0.170000,0,0.020000;%
PMS685,0,0.250000,0,0.030000;%
PMS686,0,0.300000,0,0.050000;%
PMS687,0.020000,0.440000,0,0.120000;%
PMS688,0.050000,0.570000,0,0.190000;%
PMS689,0.070000,0.770000,0,0.340000;%
PMS690,0,0.970000,0,0.590000;%
PMS691,0,0.150000,0.080000,0.010000;%
PMS692,0,0.230000,0.100000,0.020000;%
PMS693,0,0.300000,0.120000,0.060000;%
PMS694,0,0.430000,0.190000,0.100000;%
PMS695,0,0.580000,0.280000,0.250000;%
PMS696,0,0.840000,0.540000,0.400000;%
PMS697,0,0.930000,0.700000,0.510000;%
PMS698,0,0.160000,0.080000,0;%
PMS699,0,0.240000,0.100000,0;%
PMS700,0,0.360000,0.140000,0;%
PMS701,0,0.530000,0.200000,0;%
PMS702,0,0.690000,0.340000,0.050000;%
PMS703,0,0.830000,0.540000,0.160000;%
PMS704,0,1,0.800000,0.270000;%
PMS705,0,0.090000,0.050000,0;%
PMS706,0,0.170000,0.100000,0;%
PMS707,0,0.300000,0.140000,0;%
PMS708,0,0.460000,0.220000,0;%
PMS709,0,0.660000,0.380000,0;%
PMS710,0,0.790000,0.580000,0;%
PMS711,0,1,0.800000,0.020000;%
PMS712,0,0.140000,0.310000,0;%
PMS713,0,0.190000,0.410000,0;%
PMS714,0,0.280000,0.540000,0;%
PMS715,0,0.370000,0.710000,0;%
PMS716,0,0.470000,0.910000,0;%
PMS717,0,0.550000,1,0.020000;%
PMS718,0,0.580000,1,0.080000;%
PMS719,0,0.100000,0.250000,0;%
PMS720,0,0.150000,0.340000,0.010000;%
PMS721,0,0.240000,0.520000,0.030000;%
PMS722,0,0.360000,0.760000,0.090000;%
PMS723,0,0.450000,0.950000,0.170000;%
PMS724,0,0.530000,1,0.370000;%
PMS725,0,0.550000,1,0.490000;%
PMS726,0,0.080000,0.230000,0.020000;%
PMS727,0,0.150000,0.340000,0.050000;%
PMS728,0,0.210000,0.480000,0.100000;%
PMS729,0,0.310000,0.610000,0.180000;%
PMS730,0,0.390000,0.760000,0.290000;%
PMS731,0,0.530000,1,0.540000;%
PMS732,0,0.560000,1,0.640000;%
PMS7401,0,0.040000,0.180000,0;%
PMS7402,0,0.060000,0.300000,0;%
PMS7403,0,0.100000,0.500000,0;%
PMS7404,0,0.090000,0.800000,0;%
PMS7405,0,0.100000,1,0;%
PMS7406,0,0.180000,1,0;%
PMS7407,0,0.220000,0.850000,0.110000;%
PMS7408,0,0.250000,0.950000,0;%
PMS7409,0,0.300000,0.950000,0;%
PMS7410,0,0.300000,0.550000,0;%
PMS7411,0,0.350000,0.690000,0;%
PMS7412,0,0.420000,1,0.070000;%
PMS7413,0,0.530000,1,0.040000;%
PMS7414,0,0.460000,1,0.110000;%
PMS7415,0,0.180000,0.150000,0;%
PMS7416,0,0.600000,0.600000,0;%
PMS7417,0,0.750000,0.750000,0;%
PMS7418,0,0.700000,0.600000,0.050000;%
PMS7419,0,0.600000,0.450000,0.180000;%
PMS7420,0,0.800000,0.420000,0.200000;%
PMS7421,0,1,0.300000,0.610000;%
PMS7422,0,0.090000,0.050000,0;%
PMS7423,0,0.550000,0.220000,0;%
PMS7424,0,0.750000,0.300000,0;%
PMS7425,0,0.900000,0.300000,0.070000;%
PMS7426,0,1,0.450000,0.180000;%
PMS7427,0,1,0.650000,0.280000;%
PMS7428,0,0.800000,0.450000,0.550000;%
PMS7429,0,0.180000,0.030000,0;%
PMS7430,0.020000,0.310000,0,0;%
PMS7431,0,0.380000,0.020000,0.050000;%
PMS7432,0,0.550000,0.030000,0.100000;%
PMS7433,0,0.750000,0.150000,0.150000;%
PMS7434,0,0.800000,0.150000,0.200000;%
PMS7435,0,1,0.100000,0.350000;%
PMS7436,0.030000,0.080000,0,0;%
PMS7437,0.060000,0.200000,0,0;%
PMS7438,0.150000,0.350000,0,0;%
PMS7439,0.200000,0.350000,0,0;%
PMS7440,0.300000,0.400000,0,0;%
PMS7441,0.360000,0.500000,0,0;%
PMS7442,0.500000,0.700000,0,0;%
PMS7443,0.060000,0.050000,0,0;%
PMS7444,0.200000,0.170000,0,0;%
PMS7445,0.300000,0.200000,0,0.030000;%
PMS7446,0.430000,0.380000,0,0;%
PMS7447,0.600000,0.580000,0,0.190000;%
PMS7448,0.320000,0.420000,0,0.550000;%
PMS7449,0.720000,1,0.770000,0.460000;%
PMS7450,0.200000,0.100000,0,0;%
PMS7451,0.400000,0.210000,0,0;%
PMS7452,0.500000,0.320000,0,0;%
PMS7453,0.500000,0.260000,0,0;%
PMS7454,0.500000,0.240000,0,0.100000;%
PMS7455,0.800000,0.530000,0,0;%
PMS7456,0.550000,0.350000,0,0.070000;%
PMS7457,0.120000,0,0.020000,0;%
PMS7458,0.400000,0,0.050000,0.060000;%
PMS7459,0.570000,0,0.060000,0.130000;%
PMS7460,1,0,0,0.050000;%
PMS7461,0.780000,0.280000,0,0;%
PMS7462,1,0.500000,0,0.100000;%
PMS7463,1,0.430000,0,0.650000;%
PMS7464,0.250000,0,0.100000,0;%
PMS7465,0.500000,0,0.250000,0;%
PMS7466,0.700000,0,0.230000,0;%
PMS7467,0.950000,0,0.250000,0;%
PMS7468,1,0.100000,0,0.280000;%
PMS7469,1,0.200000,0,0.400000;%
PMS7470,0.800000,0.150000,0,0.450000;%
PMS7471,0.280000,0,0.140000,0;%
PMS7472,0.520000,0,0.250000,0;%
PMS7473,0.700000,0,0.380000,0.080000;%
PMS7474,0.900000,0,0.280000,0.220000;%
PMS7475,0.500000,0,0.250000,0.300000;%
PMS7476,1,0,0.430000,0.600000;%
PMS7477,0.800000,0,0.100000,0.680000;%
PMS7478,0.180000,0,0.140000,0;%
PMS7479,0.550000,0,0.500000,0;%
PMS7480,0.600000,0,0.500000,0;%
PMS7481,0.600000,0,0.550000,0;%
PMS7482,0.800000,0,0.750000,0;%
PMS7483,0.850000,0,1,0.550000;%
PMS7484,1,0,0.850000,0.500000;%
PMS7485,0.060000,0,0.100000,0;%
PMS7486,0.200000,0,0.300000,0;%
PMS7487,0.300000,0,0.450000,0;%
PMS7488,0.430000,0,0.600000,0;%
PMS7489,0.600000,0,0.800000,0.070000;%
PMS7490,0.450000,0,0.800000,0.350000;%
PMS7491,0.320000,0,1,0.400000;%
PMS7492,0.120000,0,0.500000,0.070000;%
PMS7493,0.140000,0,0.360000,0.100000;%
PMS7494,0.250000,0,0.400000,0.150000;%
PMS7495,0.250000,0,0.800000,0.300000;%
PMS7496,0.400000,0,1,0.380000;%
PMS7497,0.400000,0.300000,0.700000,0.250000;%
PMS7498,0.250000,0,1,0.800000;%
PMS7499,0,0.020000,0.150000,0;%
PMS7500,0,0.020000,0.150000,0.030000;%
PMS7501,0,0.040000,0.200000,0.060000;%
PMS7502,0,0.080000,0.350000,0.100000;%
PMS7503,0,0.120000,0.350000,0.250000;%
PMS7504,0,0.250000,0.450000,0.400000;%
PMS7505,0,0.300000,0.700000,0.550000;%
PMS7506,0,0.050000,0.150000,0;%
PMS7507,0,0.100000,0.300000,0;%
PMS7508,0,0.150000,0.400000,0.040000;%
PMS7509,0,0.200000,0.500000,0.050000;%
PMS7510,0,0.300000,0.720000,0.110000;%
PMS7511,0,0.450000,1,0.250000;%
PMS7512,0,0.460000,1,0.330000;%
PMS7513,0,0.180000,0.280000,0.030000;%
PMS7514,0,0.240000,0.380000,0.050000;%
PMS7515,0,0.350000,0.500000,0.120000;%
PMS7516,0,0.520000,1,0.350000;%
PMS7517,0,0.600000,1,0.440000;%
PMS7518,0,0.400000,0.550000,0.600000;%
PMS7519,0.500000,0.600000,1,0.480000;%
PMS7520,0,0.160000,0.190000,0;%
PMS7521,0,0.250000,0.200000,0.100000;%
PMS7522,0,0.400000,0.300000,0.160000;%
PMS7523,0,0.400000,0.350000,0.200000;%
PMS7524,0,0.550000,0.600000,0.270000;%
PMS7525,0,0.450000,0.500000,0.300000;%
PMS7526,0,0.650000,1,0.350000;%
PMS7527,0,0.020000,0.060000,0.070000;%
PMS7528,0,0.030000,0.100000,0.100000;%
PMS7529,0,0.040000,0.120000,0.170000;%
PMS7530,0,0.080000,0.210000,0.320000;%
PMS7531,0,0.100000,0.270000,0.500000;%
PMS7532,0,0.170000,0.500000,0.650000;%
PMS7533,0,0.220000,0.850000,0.850000;%
PMS7534,0,0.020000,0.080000,0.100000;%
PMS7535,0,0.030000,0.150000,0.200000;%
PMS7536,0,0.040000,0.220000,0.320000;%
PMS7537,0.030000,0,0.100000,0.200000;%
PMS7538,0.090000,0,0.130000,0.300000;%
PMS7539,0.020000,0,0.090000,0.360000;%
PMS7540,0,0,0,0.720000;%
PMS7541,0.020000,0,0,0.050000;%
PMS7542,0.100000,0,0.030000,0.160000;%
PMS7543,0.070000,0,0,0.300000;%
PMS7544,0.100000,0.010000,0,0.400000;%
PMS7545,0.230000,0.020000,0,0.630000;%
PMS7546,0.330000,0.040000,0,0.720000;%
PMS7547,0.350000,0.040000,0,0.940000;%
PMSBlack,0,0.130000,0.490000,0.980000}
\def\list{PMS100,PMS101,PMS102,PMS103,PMS104,PMS105,PMS106,PMS107,PMS108,PMS109,PMS110,PMS111,PMS112,PMS113,PMS114,PMS115,PMS116,PMS117,PMS118,PMS119,PMS120,PMS1205,PMS121,PMS1215,PMS122,PMS1225,PMS123,PMS1235,PMS124,PMS1245,PMS125,PMS1255,PMS126,PMS1265,PMS127,PMS128,PMS129,PMS130,PMS131,PMS132,PMS133,PMS134,PMS1345,PMS135,PMS1355,PMS136,PMS1365,PMS137,PMS1375,PMS138,PMS1385,PMS139,PMS1395,PMS140,PMS1405,PMS141,PMS142,PMS143,PMS144,PMS145,PMS146,PMS147,PMS148,PMS1485,PMS149,PMS1495,PMS150,PMS1505,PMS151,PMS152,PMS1525,PMS153,PMS1535,PMS154,PMS1545,PMS155,PMS1555,PMS156,PMS1565,PMS157,PMS1575,PMS158,PMS1585,PMS159,PMS1595,PMS160,PMS1605,PMS161,PMS1615,PMS162,PMS1625,PMS163,PMS1635,PMS164,PMS1645,PMS165,PMS1655,PMS166,PMS1665,PMS167,PMS1675,PMS168,PMS1685,PMS169,PMS170,PMS171,PMS172,PMS173,PMS174,PMS175,PMS176,PMS1765,PMS1767,PMS177,PMS1775,PMS1777,PMS178,PMS1785,PMS1787,PMS1788,PMS179,PMS1795,PMS1797,PMS180,PMS1805,PMS1807,PMS181,PMS1815,PMS1817,PMS182,PMS183,PMS184,PMS185,P
MS186,PMS187,PMS188,PMS189,PMS1895,PMS190,PMS1905,PMS191,PMS1915,PMS192,PMS1925,PMS193,PMS1935,PMS194,PMS1945,PMS195,PMS1955,PMS196,PMS197,PMS198,PMS199,PMS200,PMS201,PMS202,PMS203,PMS204,PMS205,PMS206,PMS207,PMS208,PMS209,PMS210,PMS211,PMS212,PMS213,PMS214,PMS215,PMS216,PMS217,PMS218,PMS219,PMS220,PMS221,PMS222,PMS223,PMS224,PMS225,PMS226,PMS227,PMS228,PMS229,PMS230,PMS231,PMS232,PMS233,PMS234,PMS235,PMS236,PMS2365,PMS237,PMS2375,PMS238,PMS2385,PMS239,PMS2395,PMS240,PMS2405,PMS241,PMS2415,PMS242,PMS2425,PMS243,PMS244,PMS245,PMS246,PMS247,PMS248,PMS249,PMS250,PMS251,PMS252,PMS253,PMS254,PMS255,PMS256,PMS2562,PMS2563,PMS2567,PMS257,PMS2572,PMS2573,PMS2577,PMS258,PMS2582,PMS2583,PMS2587,PMS259,PMS2592,PMS2593,PMS2597,PMS260,PMS2602,PMS2603,PMS2607,PMS261,PMS2612,PMS2613,PMS2617,PMS262,PMS2622,PMS2623,PMS2627,PMS263,PMS2635,PMS264,PMS2645,PMS265,PMS2655,PMS266,PMS2665,PMS267,PMS268,PMS2685,PMS269,PMS2695,PMS270,PMS2705,PMS2706,PMS2707,PMS2708,PMS271,PMS2715,PMS2716,PMS2717,PMS27
18,PMS272,PMS2725,PMS2726,PMS2727,PMS2728,PMS273,PMS2735,PMS2736,PMS2738,PMS274,PMS2745,PMS2746,PMS2747,PMS2748,PMS275,PMS2755,PMS2756,PMS2757,PMS2758,PMS276,PMS2765,PMS2766,PMS2767,PMS2768,PMS277,PMS278,PMS279,PMS280,PMS281,PMS282,PMS283,PMS284,PMS285,PMS286,PMS287,PMS288,PMS289,PMS290,PMS2905,PMS291,PMS2915,PMS292,PMS2925,PMS293,PMS2935,PMS294,PMS2945,PMS295,PMS2955,PMS296,PMS2965,PMS297,PMS2975,PMS298,PMS2985,PMS299,PMS2995,PMS300,PMS3005,PMS301,PMS3015,PMS302,PMS3025,PMS303,PMS3035,PMS304,PMS305,PMS306,PMS307,PMS308,PMS309,PMS310,PMS3105,PMS311,PMS3115,PMS312,PMS3125,PMS313,PMS3135,PMS314,PMS3145,PMS315,PMS3155,PMS316,PMS3165,PMS317,PMS318,PMS319,PMS320,PMS321,PMS322,PMS323,PMS324,PMS3242,PMS3245,PMS3248,PMS325,PMS3252,PMS3255,PMS3258,PMS326,PMS3262,PMS3265,PMS3268,PMS327,PMS3272,PMS3275,PMS3278,PMS328,PMS3282,PMS3285,PMS3288,PMS329,PMS3292,PMS3295,PMS3298,PMS330,PMS3302,PMS3305,PMS3308,PMS331,PMS332,PMS333,PMS334,PMS335,PMS336,PMS337,PMS3375,PMS338,PMS3385,PMS339,PMS3395
,PMS340,PMS3405,PMS341,PMS3415,PMS342,PMS3425,PMS343,PMS3435,PMS344,PMS345,PMS346,PMS347,PMS348,PMS349,PMS350,PMS351,PMS352,PMS353,PMS354,PMS355,PMS356,PMS357,PMS358,PMS359,PMS360,PMS361,PMS362,PMS363,PMS364,PMS365,PMS366,PMS367,PMS368,PMS369,PMS370,PMS371,PMS372,PMS373,PMS374,PMS375,PMS376,PMS377,PMS378,PMS379,PMS380,PMS381,PMS382,PMS383,PMS384,PMS385,PMS386,PMS387,PMS388,PMS389,PMS390,PMS391,PMS392,PMS393,PMS3935,PMS394,PMS3945,PMS395,PMS3955,PMS396,PMS3965,PMS397,PMS3975,PMS398,PMS3985,PMS399,PMS3995,PMS400,PMS401,PMS402,PMS403,PMS404,PMS405,PMS406,PMS407,PMS408,PMS409,PMS410,PMS411,PMS412,PMS413,PMS414,PMS415,PMS416,PMS417,PMS418,PMS419,PMS420,PMS421,PMS422,PMS423,PMS424,PMS425,PMS426,PMS427,PMS428,PMS429,PMS430,PMS431,PMS432,PMS433,PMS434,PMS435,PMS436,PMS437,PMS438,PMS439,PMS440,PMS441,PMS442,PMS443,PMS444,PMS445,PMS446,PMS447,PMS448,PMS4485,PMS449,PMS4495,PMS450,PMS4505,PMS451,PMS4515,PMS452,PMS4525,PMS453,PMS4535,PMS454,PMS4545,PMS455,PMS456,PMS457,PMS458,PMS459,PMS46
0,PMS461,PMS462,PMS4625,PMS463,PMS4635,PMS464,PMS4645,PMS465,PMS4655,PMS466,PMS4665,PMS467,PMS4675,PMS468,PMS4685,PMS469,PMS4695,PMS470,PMS4705,PMS471,PMS4715,PMS472,PMS4725,PMS473,PMS4735,PMS474,PMS4745,PMS475,PMS4755,PMS476,PMS477,PMS478,PMS479,PMS480,PMS481,PMS482,PMS483,PMS484,PMS485,PMS486,PMS487,PMS488,PMS489,PMS490,PMS491,PMS492,PMS493,PMS494,PMS495,PMS496,PMS497,PMS4975,PMS498,PMS4985,PMS499,PMS4995,PMS500,PMS5005,PMS501,PMS5015,PMS502,PMS5025,PMS503,PMS5035,PMS504,PMS505,PMS506,PMS507,PMS508,PMS509,PMS510,PMS511,PMS5115,PMS512,PMS5125,PMS513,PMS5135,PMS514,PMS5145,PMS515,PMS5155,PMS516,PMS5165,PMS517,PMS5175,PMS518,PMS5185,PMS519,PMS5195,PMS520,PMS5205,PMS521,PMS5215,PMS522,PMS5225,PMS523,PMS5235,PMS524,PMS5245,PMS525,PMS5255,PMS526,PMS5265,PMS527,PMS5275,PMS528,PMS5285,PMS529,PMS5295,PMS530,PMS5305,PMS531,PMS5315,PMS532,PMS533,PMS534,PMS535,PMS536,PMS537,PMS538,PMS539,PMS5395,PMS540,PMS5405,PMS541,PMS5415,PMS542,PMS5425,PMS543,PMS5435,PMS544,PMS5445,PMS545,PMS5455,P
MS546,PMS5463,PMS5467,PMS547,PMS5473,PMS5477,PMS548,PMS5483,PMS5487,PMS549,PMS5493,PMS5497,PMS550,PMS5503,PMS5507,PMS551,PMS5513,PMS5517,PMS552,PMS5523,PMS5527,PMS553,PMS5535,PMS554,PMS5545,PMS555,PMS5555,PMS556,PMS5565,PMS557,PMS5575,PMS558,PMS5585,PMS559,PMS5595,PMS560,PMS5605,PMS561,PMS5615,PMS562,PMS5625,PMS563,PMS5635,PMS564,PMS5645,PMS565,PMS5655,PMS566,PMS5665,PMS567,PMS568,PMS569,PMS570,PMS571,PMS572,PMS573,PMS574,PMS5743,PMS5747,PMS575,PMS5753,PMS5757,PMS576,PMS5763,PMS5767,PMS577,PMS5773,PMS5777,PMS578,PMS5783,PMS5787,PMS579,PMS5793,PMS5797,PMS580,PMS5803,PMS5807,PMS581,PMS5815,PMS582,PMS5825,PMS583,PMS5835,PMS584,PMS5845,PMS585,PMS5855,PMS586,PMS5865,PMS587,PMS5875,PMS600,PMS601,PMS602,PMS603,PMS604,PMS605,PMS606,PMS607,PMS608,PMS609,PMS610,PMS611,PMS612,PMS613,PMS614,PMS615,PMS616,PMS617,PMS618,PMS619,PMS620,PMS621,PMS622,PMS623,PMS624,PMS625,PMS626,PMS627,PMS628,PMS629,PMS630,PMS631,PMS632,PMS633,PMS634,PMS635,PMS636,PMS637,PMS638,PMS639,PMS640,PMS641,PMS642,PMS6
43,PMS644,PMS645,PMS646,PMS647,PMS648,PMS649,PMS650,PMS651,PMS652,PMS653,PMS654,PMS655,PMS656,PMS657,PMS658,PMS659,PMS660,PMS661,PMS662,PMS663,PMS664,PMS665,PMS666,PMS667,PMS668,PMS669,PMS670,PMS671,PMS672,PMS673,PMS674,PMS675,PMS676,PMS677,PMS678,PMS679,PMS680,PMS681,PMS682,PMS683,PMS684,PMS685,PMS686,PMS687,PMS688,PMS689,PMS690,PMS691,PMS692,PMS693,PMS694,PMS695,PMS696,PMS697,PMS698,PMS699,PMS700,PMS701,PMS702,PMS703,PMS704,PMS705,PMS706,PMS707,PMS708,PMS709,PMS710,PMS711,PMS712,PMS713,PMS714,PMS715,PMS716,PMS717,PMS718,PMS719,PMS720,PMS721,PMS722,PMS723,PMS724,PMS725,PMS726,PMS727,PMS728,PMS729,PMS730,PMS731,PMS732,PMS7401,PMS7402,PMS7403,PMS7404,PMS7405,PMS7406,PMS7407,PMS7408,PMS7409,PMS7410,PMS7411,PMS7412,PMS7413,PMS7414,PMS7415,PMS7416,PMS7417,PMS7418,PMS7419,PMS7420,PMS7421,PMS7422,PMS7423,PMS7424,PMS7425,PMS7426,PMS7427,PMS7428,PMS7429,PMS7430,PMS7431,PMS7432,PMS7433,PMS7434,PMS7435,PMS7436,PMS7437,PMS7438,PMS7439,PMS7440,PMS7441,PMS7442,PMS7443,PMS7444,PMS7445,PMS7
446,PMS7447,PMS7448,PMS7449,PMS7450,PMS7451,PMS7452,PMS7453,PMS7454,PMS7455,PMS7456,PMS7457,PMS7458,PMS7459,PMS7460,PMS7461,PMS7462,PMS7463,PMS7464,PMS7465,PMS7466,PMS7467,PMS7468,PMS7469,PMS7470,PMS7471,PMS7472,PMS7473,PMS7474,PMS7475,PMS7476,PMS7477,PMS7478,PMS7479,PMS7480,PMS7481,PMS7482,PMS7483,PMS7484,PMS7485,PMS7486,PMS7487,PMS7488,PMS7489,PMS7490,PMS7491,PMS7492,PMS7493,PMS7494,PMS7495,PMS7496,PMS7497,PMS7498,PMS7499,PMS7500,PMS7501,PMS7502,PMS7503,PMS7504,PMS7505,PMS7506,PMS7507,PMS7508,PMS7509,PMS7510,PMS7511,PMS7512,PMS7513,PMS7514,PMS7515,PMS7516,PMS7517,PMS7518,PMS7519,PMS7520,PMS7521,PMS7522,PMS7523,PMS7524,PMS7525,PMS7526,PMS7527,PMS7528,PMS7529,PMS7530,PMS7531,PMS7532,PMS7533,PMS7534,PMS7535,PMS7536,PMS7537,PMS7538,PMS7539,PMS7540,PMS7541,PMS7542,PMS7543,PMS7544,PMS7545,PMS7546,PMS7547,PMSBlack}
\makeatletter
\@for \x:=\list \do
{\colorbox {\x }{(\x)} }
\end{document}\endinput
0
Reply gouailles (1755) 7/19/2011 9:28:01 PM
GL <[email protected]> writes:
> From the palette, would it be possible to set up a function that give
> the correspondance between cmyk and PMS (Pantone Matching System) ?
>
> Not so easy at first glance...
it's called a lookup table.
> However, it could be quite easy to extract the CMYK values from the HTML
> file in order to provide a PMS option for xcolor in about one hour for
> a waked guy ;-)
however, it won't substitute for the purchased product, which is tuned
to the known properties of your output device (the colour parameters on
the web site are indicative only).
--
Robin Fairbairns, Cambridge
0
Reply rf10 (3613) 7/19/2011 11:11:24 PM
On Jul 19, 5:28=A0pm, GL <[email protected]> wrote:
> Le 19/07/2011 22:01, Joris Pinkse a =E9crit :
>
>
>
>
>
>
>
>
>
>
>
> >> Yes ? And this one is nice too:
>
>
> >> since it defines some named colors (easier to memorize/use/read in the
> >> source) However I didn't test them and i'm not sure of the result in a
> >> pdf. But it could be a starting point to add a "pantone" option to
> >> xcolor... may be underground (i heard Pantone colors to be "protected"=
,
> >> even if such "protection" sounds not legal in Europe...)
>
> > true, but there are far fewer of them.....
>
> Now you should compare ;-)
>
> \documentclass [a4paper]{article}
> \usepackage [cmyk]{xcolor}
> \pdfpageattr{/Group <</S /Transparency /I true /CS /DeviceRGB>>}
> \begin{document}
>
> \def\colornameprefix{XC@}
> \preparecolorset{cmyk}{}{}{%
> PMS100,0,0,0.510000,0;%
> PMS101,0,0,0.790000,0;%
> PMS102,0,0.010000,0.950000,0;%
> PMS103,0,0.030000,1,0.180000;%
> PMS104,0,0.030000,1,0.300000;%
> PMS105,0,0.030000,1,0.500000;%
> PMS106,0,0.020000,0.690000,0;%
> PMS107,0,0.040000,0.790000,0;%
> PMS108,0,0.060000,0.950000,0;%
> PMS109,0,0.100000,1,0;%
> PMS110,0,0.120000,1,0.070000;%
> PMS111,0,0.110000,1,0.270000;%
> PMS112,0,0.100000,1,0.380000;%
> PMS113,0,0.070000,0.660000,0;%
> PMS114,0,0.080000,0.730000,0;%
> PMS115,0,0.090000,0.800000,0;%
> PMS116,0,0.160000,1,0;%
> PMS117,0,0.180000,1,0.150000;%
> PMS118,0,0.180000,1,0.270000;%
> PMS119,0,0.120000,1,0.490000;%
> PMS120,0,0.090000,0.580000,0;%
> PMS1205,0,0.050000,0.310000,0;%
> PMS121,0,0.110000,0.690000,0;%
> PMS1215,0,0.090000,0.450000,0;%
> PMS122,0,0.170000,0.800000,0;%
> PMS1225,0,0.170000,0.620000,0;%
> PMS123,0,0.240000,0.940000,0;%
> PMS1235,0,0.290000,0.910000,0;%
> PMS124,0,0.280000,1,0.060000;%
> PMS1245,0,0.280000,1,0.180000;%
> PMS125,0,0.260000,1,0.260000;%
> PMS1255,0,0.270000,1,0.340000;%
> PMS126,0,0.250000,1,0.370000;%
> PMS1265,0,0.270000,1,0.510000;%
> PMS127,0,0.070000,0.500000,0;%
> PMS128,0,0.110000,0.650000,0;%
> PMS129,0,0.160000,0.770000,0;%
> PMS130,0,0.300000,1,0;%
> PMS131,0,0.320000,1,0.090000;%
> PMS132,0,0.280000,1,0.300000;%
> PMS133,0,0.200000,1,0.560000;%
> PMS134,0,0.110000,0.450000,0;%
> PMS1345,0,0.140000,0.470000,0;%
> PMS135,0,0.190000,0.600000,0;%
> PMS1355,0,0.200000,0.560000,0;%
> PMS136,0,0.270000,0.760000,0;%
> PMS1365,0,0.290000,0.720000,0;%
> PMS137,0,0.350000,0.900000,0;%
> PMS1375,0,0.400000,0.900000,0;%
> PMS138,0,0.420000,1,0.010000;%
> PMS1385,0,0.440000,1,0.070000;%
> PMS139,0,0.370000,1,0.230000;%
> PMS1395,0,0.410000,1,0.370000;%
> PMS140,0,0.270000,1,0.540000;%
> PMS1405,0,0.360000,1,0.630000;%
> PMS141,0,0.190000,0.510000,0;%
> PMS142,0,0.280000,0.760000,0;%
> PMS143,0,0.350000,0.850000,0;%
> PMS144,0,0.480000,1,0;%
> PMS145,0,0.470000,1,0.080000;%
> PMS146,0,0.430000,1,0.330000;%
> PMS147,0,0.280000,1,0.560000;%
> PMS148,0,0.160000,0.370000,0;%
> PMS1485,0,0.270000,0.540000,0;%
> PMS149,0,0.230000,0.470000,0;%
> PMS1495,0,0.330000,0.670000,0;%
> PMS150,0,0.350000,0.700000,0;%
> PMS1505,0,0.420000,0.770000,0;%
> PMS151,0,0.480000,0.950000,0;%
> PMS152,0,0.510000,1,0.010000;%
> PMS1525,0,0.580000,1,0.100000;%
> PMS153,0,0.460000,1,0.180000;%
> PMS1535,0,0.530000,1,0.380000;%
> PMS154,0,0.460000,1,0.340000;%
> PMS1545,0,0.530000,1,0.720000;%
> PMS155,0,0.120000,0.280000,0;%
> PMS1555,0,0.220000,0.340000,0;%
> PMS156,0,0.220000,0.420000,0;%
> PMS1565,0,0.340000,0.490000,0;%
> PMS157,0,0.430000,0.700000,0;%
> PMS1575,0,0.450000,0.720000,0;%
> PMS158,0,0.610000,0.970000,0;%
> PMS1585,0,0.560000,0.900000,0;%
> PMS159,0,0.660000,1,0.070000;%
> PMS1595,0,0.590000,1,0.050000;%
> PMS160,0,0.620000,1,0.320000;%
> PMS1605,0,0.560000,1,0.300000;%
> PMS161,0,0.520000,1,0.640000;%
> PMS1615,0,0.560000,1,0.430000;%
> PMS162,0,0.150000,0.220000,0;%
> PMS1625,0,0.310000,0.370000,0;%
> PMS163,0,0.310000,0.440000,0;%
> PMS1635,0,0.390000,0.480000,0;%
> PMS164,0,0.460000,0.730000,0;%
> PMS1645,0,0.490000,0.660000,0;%
> PMS165,0,0.590000,0.960000,0;%
> PMS1655,0,0.630000,0.910000,0;%
> PMS166,0,0.640000,1,0;%
> PMS1665,0,0.680000,1,0;%
> PMS167,0,0.600000,1,0.170000;%
> PMS1675,0,0.670000,1,0.280000;%
> PMS168,0,0.570000,1,0.590000;%
> PMS1685,0,0.680000,1,0.440000;%
> PMS169,0,0.200000,0.200000,0;%
> PMS170,0,0.400000,0.440000,0;%
> PMS171,0,0.530000,0.680000,0;%
> PMS172,0,0.660000,0.880000,0;%
> PMS173,0,0.690000,1,0.040000;%
> PMS174,0,0.700000,1,0.360000;%
> PMS175,0,0.650000,1,0.600000;%
> PMS176,0,0.250000,0.180000,0;%
> PMS1765,0,0.380000,0.210000,0;%
> PMS1767,0,0.270000,0.120000,0;%
> PMS177,0,0.450000,0.400000,0;%
> PMS1775,0,0.470000,0.290000,0;%
> PMS1777,0,0.580000,0.360000,0;%
> PMS178,0,0.590000,0.560000,0;%
> PMS1785,0,0.670000,0.500000,0;%
> PMS1787,0,0.760000,0.600000,0;%
> PMS1788,0,0.840000,0.880000,0;%
> PMS179,0,0.790000,1,0;%
> PMS1795,0,0.940000,1,0;%
> PMS1797,0,1,0.990000,0.040000;%
> PMS180,0,0.790000,1,0.110000;%
> PMS1805,0,0.910000,1,0.230000;%
> PMS1807,0,1,0.960000,0.280000;%
> PMS181,0,0.740000,1,0.470000;%
> PMS1815,0,0.900000,1,0.510000;%
> PMS1817,0,0.900000,1,0.660000;%
> PMS182,0,0.260000,0.100000,0;%
> PMS183,0,0.460000,0.210000,0;%
> PMS184,0,0.680000,0.410000,0;%
> PMS185,0,0.910000,0.760000,0;%
> PMS186,0,1,0.810000,0.040000;%
> PMS187,0,1,0.790000,0.200000;%
> PMS188,0,0.970000,1,0.500000;%
> PMS189,0,0.370000,0.100000,0;%
> PMS1895,0,0.280000,0.070000,0;%
> PMS190,0,0.550000,0.220000,0;%
> PMS1905,0,0.410000,0.090000,0;%
> PMS191,0,0.760000,0.380000,0;%
> PMS1915,0,0.710000,0.200000,0;%
> PMS192,0,1,0.680000,0;%
> PMS1925,0,1,0.550000,0;%
> PMS193,0,1,0.660000,0.130000;%
> PMS1935,0,1,0.570000,0.050000;%
> PMS194,0,1,0.640000,0.330000;%
> PMS1945,0,1,0.560000,0.190000;%
> PMS195,0,1,0.600000,0.550000;%
> PMS1955,0,1,0.600000,0.370000;%
> PMS196,0,0.250000,0.040000,0;%
> PMS197,0,0.450000,0.100000,0;%
> PMS198,0,0.780000,0.330000,0;%
> PMS199,0,1,0.620000,0;%
> PMS200,0,1,0.630000,0.120000;%
> PMS201,0,1,0.630000,0.290000;%
> PMS202,0,1,0.610000,0.430000;%
> PMS203,0,0.340000,0.030000,0;%
> PMS204,0,0.580000,0.030000,0;%
> PMS205,0,0.840000,0.090000,0;%
> PMS206,0,1,0.380000,0.030000;%
> PMS207,0,1,0.430000,0.190000;%
> PMS208,0,1,0.360000,0.370000;%
> PMS209,0,1,0.340000,0.530000;%
> PMS210,0,0.390000,0.060000,0;%
> PMS211,0,0.550000,0.080000,0;%
> PMS212,0,0.720000,0.110000,0;%
> PMS213,0,0.950000,0.270000,0;%
> PMS214,0,1,0.340000,0.080000;%
> PMS215,0,1,0.350000,0.270000;%
> PMS216,0,0.950000,0.400000,0.490000;%
> PMS217,0,0.280000,0,0;%
> PMS218,0.020000,0.610000,0,0;%
> PMS219,0.010000,0.880000,0,0;%
> PMS220,0,1,0.130000,0.170000;%
> PMS221,0,1,0.150000,0.300000;%
> PMS222,0,1,0.100000,0.590000;%
> PMS223,0,0.460000,0,0;%
> PMS224,0.010000,0.630000,0,0;%
> PMS225,0.010000,0.830000,0,0;%
> PMS226,0,1,0,0;%
> PMS227,0,1,0.070000,0.190000;%
> PMS228,0,1,0.040000,0.410000;%
> PMS229,0,1,0.150000,0.600000;%
> PMS230,0,0.340000,0,0;%
> PMS231,0.010000,0.520000,0,0;%
> PMS232,0.030000,0.670000,0,0;%
> PMS233,0.110000,1,0,0;%
> PMS234,0.060000,1,0,0.260000;%
> PMS235,0.050000,1,0,0.400000;%
> PMS236,0.010000,0.300000,0,0;%
> PMS2365,0.020000,0.270000,0,0;%
> PMS237,0.030000,0.490000,0,0;%
> PMS2375,0.100000,0.570000,0,0;%
> PMS238,0.060000,0.630000,0,0;%
> PMS2385,0.190000,0.790000,0,0;%
> PMS239,0.110000,0.790000,0,0;%
> PMS2395,0.270000,0.950000,0,0;%
> PMS240,0.180000,0.940000,0,0;%
> PMS2405,0.340000,1,0,0;%
> PMS241,0.270000,1,0,0.020000;%
> PMS2415,0.330000,1,0,0.080000;%
> PMS242,0.100000,1,0,0.490000;%
> PMS2425,0.370000,1,0,0.260000;%
> PMS243,0.050000,0.290000,0,0;%
> PMS244,0.090000,0.380000,0,0;%
> PMS245,0.140000,0.530000,0,0;%
> PMS246,0.290000,0.900000,0,0;%
> PMS247,0.360000,1,0,0;%
> PMS248,0.400000,1,0,0.020000;%
> PMS249,0.400000,1,0,0.280000;%
> PMS250,0.050000,0.180000,0,0;%
> PMS251,0.130000,0.390000,0,0;%
> PMS252,0.240000,0.560000,0,0;%
> PMS253,0.430000,0.950000,0,0;%
> PMS254,0.500000,1,0,0;%
> PMS255,0.510000,1,0,0.250000;%
> PMS256,0.070000,0.200000,0,0;%
> PMS2562,0.190000,0.350000,0,0;%
> PMS2563,0.220000,0.330000,0,0;%
> PMS2567,0.290000,0.360000,0,0;%
> PMS257,0.140000,0.340000,0,0;%
> PMS2572,0.300000,0.470000,0,0;%
> PMS2573,0.300000,0.430000,0,0;%
> PMS2577,0.400000,0.450000,0,0;%
> PMS258,0.430000,0.760000,0,0;%
> PMS2582,0.460000,0.720000,0,0;%
> PMS2583,0.460000,0.630000,0,0;%
> PMS2587,0.590000,0.660000,0,0;%
> PMS259,0.560000,1,0,0.150000;%
> PMS2592,0.600000,0.900000,0,0;%
> PMS2593,0.610000,0.890000,0,0;%
> PMS2597,0.850000,1,0,0;%
> PMS260,0.520000,1,0,0.260000;%
> PMS2602,0.630000,1,0,0.030000;%
> PMS2603,0.690000,1,0,0.020000;%
> PMS2607,0.810000,1,0,0.070000;%
> PMS261,0.480000,1,0,0.400000;%
> PMS2612,0.640000,1,0,0.140000;%
> PMS2613,0.630000,1,0,0.150000;%
> PMS2617,0.790000,1,0,0.150000;%
> PMS262,0.450000,1,0,0.550000;%
> PMS2622,0.580000,1,0,0.440000;%
> PMS2623,0.590000,1,0,0.320000;%
> PMS2627,0.770000,1,0,0.310000;%
> PMS263,0.100000,0.140000,0,0;%
> PMS2635,0.280000,0.270000,0,0;%
> PMS264,0.260000,0.280000,0,0;%
> PMS2645,0.400000,0.360000,0,0;%
> PMS265,0.540000,0.560000,0,0;%
> PMS2655,0.540000,0.490000,0,0;%
> PMS266,0.790000,0.900000,0,0;%
> PMS2665,0.620000,0.600000,0,0;%
> PMS267,0.890000,1,0,0;%
> PMS268,0.820000,1,0,0.120000;%
> PMS2685,0.960000,1,0,0.100000;%
> PMS269,0.780000,1,0,0.330000;%
> PMS2695,0.910000,1,0,0.490000;%
> PMS270,0.310000,0.270000,0,0;%
> PMS2705,0.400000,0.300000,0,0;%
> PMS2706,0.190000,0.090000,0,0;%
> PMS2707,0.170000,0.060000,0,0;%
> PMS2708,0.260000,0.100000,0,0;%
> PMS271,0.430000,0.370000,0,0;%
> PMS2715,0.570000,0.450000,0,0;%
> PMS2716,0.450000,0.290000,0,0;%
> PMS2717,0.290000,0.120000,0,0;%
> PMS2718,0.670000,0.410000,0,0;%
> PMS272,0.580000,0.480000,0,0;%
> PMS2725,0.770000,0.680000,0,0;%
> PMS2726,0.790000,0.660000,0,0;%
> PMS2727,0.710000,0.420000,0,0;%
> PMS2728,0.960000,0.690000,0,0;%
> PMS273,1,0.960000,0,0.080000;%
> PMS2735,1,0.950000,0,0;%
> PMS2736,1,0.910000,0,0;%
> PMS2738,1,0.870000,0,0.020000;%
> PMS274,1,1,0,0.280000;%
> PMS2745,1,0.950000,0,0.150000;%
> PMS2746,1,0.920000,0,0.100000;%
> PMS2747,1,0.860000,0,0.150000;%
> PMS2748,1,0.880000,0,0.150000;%
> PMS275,0.980000,1,0,0.430000;%
> PMS2755,1,0.970000,0,0.300000;%
> PMS2756,1,0.940000,0,0.290000;%
> PMS2757,1,0.820000,0,0.300000;%
> PMS2758,1,0.800000,0,0.260000;%
> PMS276,0.980000,1,0,0.550000;%
> PMS2765,1,0.970000,0,0.450000;%
> PMS2766,1,0.940000,0,0.470000;%
> PMS2767,1,0.780000,0,0.540000;%
> PMS2768,1,0.780000,0,0.440000;%
> PMS277,0.270000,0.070000,0,0;%
> PMS278,0.390000,0.140000,0,0;%
> PMS279,0.680000,0.340000,0,0;%
> PMS280,1,0.720000,0,0.180000;%
> PMS281,1,0.720000,0,0.320000;%
> PMS282,1,0.680000,0,0.540000;%
> PMS283,0.350000,0.090000,0,0;% ...
>
great, thanks.
0
Reply pinkse (345) 7/20/2011 12:18:34 AM
Le 20/07/2011 01:11, Robin Fairbairns a �crit :
> GL<[email protected]> writes:
>
>> From the palette, would it be possible to set up a function that give
>> the correspondance between cmyk and PMS (Pantone Matching System) ?
>>
>> Not so easy at first glance...
>
> it's called a lookup table.
I meant arithmetics, not a graph ! (P;M;S) = f(c;m;y;k) where f is an
analytic expression
>> However, it could be quite easy to extract the CMYK values from the HTML
>> file in order to provide a PMS option for xcolor in about one hour for
>> a waked guy ;-)
>
> however, it won't substitute for the purchased product, which is tuned
> to the known properties of your output device (the colour parameters on
> the web site are indicative only).
Ah thanks.
There is also a nice palette in PDF format here (14 pages):
http://www.benedict.edu/divisions/inseff/mis/pdf
/web/bc_web_dev_pantone_color_bridge_cmyk_pc.pdf
0
Reply gouailles (1755) 7/20/2011 6:56:40 AM
GL <[email protected]> writes:
> Le 20/07/2011 01:11, Robin Fairbairns a \'ecrit :
>> GL<[email protected]> writes:
>>
>>> From the palette, would it be possible to set up a function that give
>>> the correspondance between cmyk and PMS (Pantone Matching System) ?
>>>
>>> Not so easy at first glance...
>>
>> it's called a lookup table.
>
> I meant arithmetics, not a graph ! (P;M;S) = f(c;m;y;k) where f is an
> analytic expression
i don't believe such a thing exists; pantone predates the days when
things were done digitally, i suspect (and see my comment about tuning).
>>> However, it could be quite easy to extract the CMYK values from the HTML
>>> file in order to provide a PMS option for xcolor in about one hour for
>>> a waked guy ;-)
well, of course.
>> however, it won't substitute for the purchased product, which is tuned
>> to the known properties of your output device (the colour parameters on
>> the web site are indicative only).
>
> Ah thanks.
>
> There is also a nice palette in PDF format here (14 pages):
>
> http://www.benedict.edu/divisions/inseff/mis/pdf
> /web/bc_web_dev_pantone_color_bridge_cmyk_pc.pdf
but again, it's necessarily a single-destination table.
(i always glaze over when looking at paint-colour charts for my own
house. part of my problem, i suspect, is that my colour vision is a bit
askew, so that i often can't see the difference between things other
people worry about, and my choices tend to be overridden as too
strident. my new wife -- of nearly 10 years -- has far worse eyesight
than mine ... and we need choose paint some time soon ... i wonder how
the exercise will go ...)
--
Robin Fairbairns, Cambridge
0
Reply rf10 (3613) 7/20/2011 9:15:53 AM
On Jul 20, 5:15=A0am, Robin Fairbairns <[email protected]> wrote:
> GL <[email protected]> writes:
> > Le 20/07/2011 01:11, Robin Fairbairns a \'ecrit :
> >> GL<[email protected]> =A0writes:
>
> >>> =A0From the palette, would it be possible to set up a function that g=
ive
> >>> the correspondance between cmyk and PMS (Pantone Matching System) ?
>
> >>> Not so easy at first glance...
>
> >> it's called a lookup table.
>
> > I meant arithmetics, not a graph ! (P;M;S) =3D f(c;m;y;k) where f is an
> > analytic expression
>
> i don't believe such a thing exists; pantone predates the days when
> things were done digitally, i suspect (and see my comment about tuning).
>
> >>> However, it could be quite easy to extract the CMYK values from the H=
TML
> >>> file in order to provide a PMS option for xcolor in about one hour fo=
r
> >>> a waked guy ;-)
>
> well, of course.
>
> >> however, it won't substitute for the purchased product, which is tuned
> >> to the known properties of your output device (the colour parameters o=
n
> >> the web site are indicative only).
>
> > Ah thanks.
>
> > There is also a nice palette in PDF format here (14 pages):
>
> >http://www.benedict.edu/divisions/inseff/mis/pdf
> > /web/bc_web_dev_pantone_color_bridge_cmyk_pc.pdf
>
> but again, it's necessarily a single-destination table.
>
> (i always glaze over when looking at paint-colour charts for my own
> house. =A0part of my problem, i suspect, is that my colour vision is a bi=
t
> askew, so that i often can't see the difference between things other
> people worry about, and my choices tend to be overridden as too
> strident. =A0my new wife -- of nearly 10 years -- has far worse eyesight
> than mine ... and we need choose paint some time soon ... i wonder how
> the exercise will go ...)
> --
> Robin Fairbairns, Cambridge
t.
Pick white. ;-)
0
Reply pinkse (345) 7/20/2011 12:03:44 PM
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Is there a way in plain TeX, pdftex, pdflatex, Context or other TeX variant to assign Pantone colors by Pantone number? I am familiar with the RGB and CMYK facilities. Alternatively, is there a Pantone to CMYK cross reference available? I understand that such a cross reference is at best an approximation. I found a list of 62 CMYK colors somewhere with Pantone numbers for most. Can anyone give me a more complete list? -- John Culleton Able Indexers and Typesetters "John Culleton" <[email protected]> schrieb im Newsbeitrag news:[email protected]... &...
newbie multiple question: color replace.. pantone color... in give eps image.
Hi all, I am working on a project.. I was given an .eps file that is cmyk but when opned looks like greyscale.. 2 boxes have names one them and each box crresponds to colors of the logo the boxes.. the logo is made of 2 colors... My questions.. the two colors by the boxes are PMS 165 2X CVC and PMS REFLEX BLUE CVC what are these colors in PS CS? When I do a color pick and go under custom I am oevrwhelmed by the PANTONE options ... The file given to me is an EPS.. when I open it in AI CS it just shows as a single image and when I outline it its just a rectangle... so I cant use AI to play w...
xcolor : \color versus \textcolor \colorbox \fcolorbox \color@fbox : Why so much fantasy ?
Hello, \color is defined with an optional argument [model]{color} \textcolor is defined with #1#{ \colorbox with #1#{ \colorlet {r}{red} \textcolor r{some text} breaks while {\color r some text } is happy. So: Why so much fantasy in the parsing of the parameters ? Regards GL <[email protected]> wrote: > \color is defined with an optional argument [model]{color} > > \textcolor is defined with #1#{ > > \colorbox with #1#{ > > > \colorlet {r}{red} > \textcolor r{some text} breaks > > while {\color r some text } is hap...
pdflatex and color package
Hi all, I got a strange error when I tried to add some coloured to a fairly complex document using pdflatex. As soon as I load the 'color' package with 'pdftex' as option, I get many error messages of the following type: For every 'figure' environment I get the following 3 error messages: ************************************************************ ! Too many }'s. \color@endbox ->\color@endgroup \egroup l.32 \end{figure} You've closed more groups than you opened. Such booboos are generally harmless, so keep going. ! LaTeX Error: \begin{document} ended...
No color using xcolor
Hi everyone, I was trying to find out how to use colors in LaTeX documents. I've found xcolor and thought that would suit me best for what I need. However there is no color in output, apart from gray. Whatever color I choose the output is presented in grayscale. For example look at this code: \documentclass[a4paper,12pt]{report} \usepackage{xcolor} \begin{document} \textcolor[rgb]{1.0,1.0,0.5}{foo text} \end{document} The above is supposed to present foo text in light yellow color, however all I see is pale, barely readable, gray. It seems that the text's color is being "...
Wrong colors with xcolor?
Hi, I've posted this already in the German newsgroup but without any answer and it's kind of urgent... Have you ever experienced that colors from xcolor are not quite correct? At the moment I have just looked at the TFT (no print) but with several PDF viewers. I set a color with RGB (e.g. with \textcolor). But it looks different than how GIMP shows this color or how Gnuplot uses this color in his diagrams. Since two independent tool behave equal and differ from xcolor I guess xcolor is wrong here. The problem is that I want to set some Text in the same color I have used in Gnu...
xcolor \color and \colorlet
Hello, xcolor \color is robust, why is not \colorlet ? Yours sincerely. GL <[email protected]> wrote: > Hello, > > xcolor \color is robust, why is not \colorlet ? Probably because the author of xcolor didn't think that \colorlet would go in a moving argument. Ciao Enrico Le 19/03/2011 14:19, Enrico Gregorio a �crit : > GL<[email protected]> wrote: > >> Hello, >> >> xcolor \color is robust, why is not \colorlet ? > > Probably because the author of xcolor didn't think > that \colorlet would go in...
Color Definitions and Pantones
Hi The CMYK color definitions given to me by the company graphic designers are not being displayed correctly in Frame. For example, if I select Pantone 2582 the CMYK values are 47.0, 65.0, 0.0, 0.0. But, if I enter these values myself, I get a completely different color. Curiously (and I'm sure this is related to the same issue), if I select, let's say, Pantone 2582 then change one of the CMYK values by adding an extra zero to the end (for example change Cyan from 47.0 to 47.00) the color changes to something completely different! This isn't just an artefact c...
Pantone colors in Ps-Tricks
Hi All, In my document, I need a Pantone color in some boxes. I used the below commands to obtain my requirement. I got the exact output in all the places except in the gradient. For gradient, automatically color changed to CMYK equivalent, but I need that also in Pantone. I used "dvips" to convert .dvi to PS and Adobe Distiller to convert PS to PDF. Kindly suggest is there any way to meet my requirement? My commands are below: ********************************* % Using spot colors with xcolor and pstricks. % process with: % $latex xcpst %$ dvips -h tex.pro -h xcolor.pro -h spot.p...
Quark and new Pantone colors
Hi all, How do you update the Pantone colors library in Quark? I have tried both eps and qxd files downloaded from Pantone's web site but it does not work for me. After following the instruction at Pantone's web site, I still dont see the new colors in the solid to process library. Any help, please? Thanks. P.S. I can open up that qxd files and see the new colors but how do I import them into Quark's color library? Regards, Tony Tony Low wrote: > > How do you update the Pantone colors library in Quark? I have tried both > eps and qxd files downloaded from Pan...
PSP7 Color Question
I discoverded Pantone colors for the first time and also discovered psp7 doesn't support them. However, are they any color charts and codes available for PSP7 that allows you to get the same shades and textures that you can get with Pantone? Or close at least? I really like the reflective colors in Pantone. Thanks in article [email protected], e-Lou at lojobe@"nospam"hotmail.com wrote on 05/25/2004 4:33 PM: > I discoverded Pantone colors for the first time and also discovered psp7 > doesn't support them. That is because... Pantone color through laser printers Hi All, I'm having a problem understanding how laser printers deal with Pantone color. As I understand it, the printer will need to convert the Pantone color to what it think is the respective CMYK values and create the closest match. What I don't understand is what this conversion logic is based on. I have a PDF that has a logo made in Pantone 321 C. When I print it locally on a laser printer I get a completely different color in comparison to another print vendor that is printing the same PDF. Could someone please point me in the direction if enlightenment, as there is cle... (xcolor) color series computation Hello, On the following example, the color series of "type" {last} ends with green. But green is not displayed... I mean not the real green. How does xcolor computes the colors ? step by step or by the mean of a barycentre between the "boundaries" / limits ? Depending on the colors and the number of tones in the series, you can get funny results... % ---------------------------------------------- \documentclass [a4paper]{minimal} \usepackage [svgnames]{xcolor} \begin{document} \definecolorseries {series}{rgb}{last}{RoyalBlue}{green} \resetcolorseries[4]{series} { \r... What do designers know about Pantone colors Not all colors are created equal - aside from the actual color itself, that is. With offset printing inks there are quite a few strange differences between the colors. Pantone Yellow Pantone colors are usually set to overprint black (or vice-versa). In printing, the black always goes down first. Pantone yellow is somewhat opaque and is not suitable for overprinting. Printers quite often substitute process yellow in this case which means a slight color shift. Pantone yellow is a strong color. Pantone Orange is a strong color and very vibrant. It always prints well. Pantone Warm Red and... Pantone colors in Illustrator CS I have to make a drawing with pantone colors in Illustrator Cs but the names of the pantone colors are different than the conventional numbers. If I open the pantone palet and select a color the name is like this; PANTONE DS 7-2C. Does anybody know how I can find for example pms 201? Thanks in advance. [email protected] (kathleen) wrote in news:[email protected]: > I have to make a drawing with pantone colors in Illustrator Cs but the > names of the pantone colors are different than the conventional > numbers. If I open the pantone palet a... Typesetting colored boxes with pdflatex How can I do something like blah blah blah [C] blah blah where [C] is a colored box with a black frame around? It has to work with pdflatex. /David David Rasmussen <[email protected]> writes: > How can I do something like > > blah blah blah [C] blah blah > > where [C] is a colored box with a black frame around? > > It has to work with pdflatex. % how about \fcolorbox{framecolor}{bgcolor}{text} %? % (color.sty req'd. Consult the grfguide for predefined colors and % package options regarding pdflatex(1). HTH Ulrich -- Getting lost in the \temporals... About "pantone colors" Dear all How can I use "pantone color" in TeX. I want to make a box filled with "Pantone 285 CV". How can I use the panton color instead of ordinary color. Thanks and Regards Saravanan,M. [email protected] (Saravanan,M.) writes: > Dear all > > How can I use "pantone color" in TeX. I want to make a box filled with > "Pantone 285 CV". How can I use the panton color instead of ordinary > color. You need a basic course on Google --> http://www.ethoughts.org/colors.htm -- Maurizio Loreti http://... Defining a color with its wavelength in xcolor Hello, I need to define a lot of color to draw the effect of a prism on a "white" color beam. I have already done the pstricks code for that, with a refraction angle depending on the wavelength, but I need to define the color of the rays, using xcolor. I went trought xcolor documentation but I did not see a simple way to do that. Since I know quite nothing about color representation in computer (or in printing), any help would be highly appreciated :-) Thank you in advance. Best regards -- Kristof "Christophe Jorssen" <[email protected]> writ... PSP7 Color Question I discoverded Pantone colors for the first time and also discovered psp7 doesn't support them. However, are they any color charts and codes available for PSP7 that allows you to get the same shades and textures that you can get with Pantone? Or close at least? I really like the reflective colors in Pantone. Thanks in article [email protected], e-Lou at lojobe@"nospam"hotmail.com wrote on 05/25/2004 4:33 PM: > I discoverded Pantone colors for the first time and also discovered psp7 > doesn't support them. That is because...
Pantone Colors in PSP 8
Greetings All: The work I do requires extensive use of Pantone Colors. If you are not familiar with Pantone, they are the industry standard for color definitions and commercial printing. I have a program from Pantone (ColorWeb Pro 2.0) which gives you a matrix for color selection. You input the Pantone color code and immediately get a color swatch with the equivalent RGB/HSL values. This program worked great with PSP 7.X where you could use the standard Windows color picker. With ColorWeb Pro active, all you had to do was click on the foreground/background color box and the Pan... | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7625756859779358, "perplexity": 15235.19767746539}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-41/segments/1410657132025.91/warc/CC-MAIN-20140914011212-00007-ip-10-196-40-205.us-west-1.compute.internal.warc.gz"} |
https://rockpool.ai/reference/_autosummary/training.adversarial_jax.pga_attack.html | training.adversarial_jax.pga_attack(params_flattened: List, net: Callable[[numpy.ndarray], numpy.ndarray], rng_key: Any, inputs: numpy.ndarray, net_out_original: numpy.ndarray, tree_def_params: Any, mismatch_loss: Callable[[numpy.ndarray, numpy.ndarray], float], attack_steps: int = 10, mismatch_level: float = 0.025, initial_std: float = 0.001) Tuple[List, Dict][source]
Performs the PGA (projected gradient ascent) based attack on the parameters of the network given inputs.
This function performs an attack on the parameters of a network, using the gradient of a supplied loss. Starting from an initial set of parameters $$\Theta$$ (params_flattened), we iteratively modify the parameters in order to worsen a supplied loss function mismatch_loss. mismatch_loss measures a comparison between the output of the network at the initial parameters (net_out_original) and the output of the network at the modified parameters $$\Theta^*$$. We compute the gradient of mismatch_loss w.r.t. the modified parameters $$\Theta^*$$, and step in a projected direction along the sign of the gradient.
The step size at each iteration for a parameter p is given by (mismatch_level * abs(p)) / attack_steps.
Parameters
• params_flattened (List) – Flattened pytree that was obtained using jax.tree_util.tree_flatten of the network parameters (obtained by net.parameters())
• net (Callable) – A function (e.g. Sequential object) that takes an np.ndarray and generates another np.ndarray
• rng_key (JaxRNGKey) – A Jax random key
• attack_steps (int) – Number of PGA steps to be taken
• mismatch_level (float) – Size by which the adversary can perturb the weights ($$\zeta$$). Attack will be in $$[\Theta-\zeta \cdot |\Theta|,\Theta+\zeta \cdot |\Theta|]$$
• initial_std (float) – Initial perturbation ($$\zeta_{initial}$$) of the parameters according to $$\Theta + \zeta_{initial} \cdot R \odot |\Theta| \; ; R \sim \mathcal{N}(0,\mathbf{I})$$
• inputs (np.ndarray) – Inputs that will be passed through the network
• net_out_original (np.ndarray) – Outputs of the network using the original weights
• tree_def_params (JaxTreeDef) – Tree structure obtained by calling jax.tree_util.tree_flatten on theta_star_unflattened. Basically defining the shape of theta/theta_star
• mismatch_loss (Callable) – Mismatch loss. Takes as input two np.ndarray s and returns a float. Example: KL divergence between softmaxed logits of the networks. Signature: mismatch_loss(target, net_output).
Returns
Tuple comprising $$\Theta^*$$ in flattened form and a dictionary holding the grads and losses for every PGA iteration
Return type
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https://www.fractalai.org/dl/2020/02/10/policy-gradient-actor-critic.html | What if we could learn the policy parameters directly? We can approach this problem by thinking of policies abstractly - Let’s consider a class of policies defined by $\theta$ and refer to such a policy as $\pi_{\theta}(a|s)$ which is a probability distribution over the action space conditioned on the state $s$. These parameters $\theta$ could be the parameters of a neural network or a simple polynomial or anything really.
Let’s note define a metric $J$ which can be used to evaluate the quality of a policy $\pi_{\theta}$. What we really want to do is maximize the expected future reward, so naturally we can write
where $R(s_{t}, a_{t})$ is the reward given by taking action $a$ in state $s$ and time $t$. The optimal set of parameters for the policy can then be written as
Now consider a trajectory $\tau = (s_{1}, a_{1}, s_{2}, a_{2}, …, s_{T})$ which is a sequence of state-action pairs until the terminal state. We are trying to learn $\theta$ that maximizes the reward of some trajectory. So in the spirit of gradient descent, we are going to take actions within our environment to sample a trajectory and then use the rewards gained from that trajectory to adjust our parameters. We can write our loss function as
where $R(\tau)$ is the cumulative reward gained by our trajectory. Our objective is to take the gradient of this function with respect to $\theta$ so that we can use the gradient descent update rule to adjust our parameters, but the reward function is not known and may not even be differentiable, but with a few clever tricks we can estimate the gradient. Recall that for any continuous function $f(x)$, $\mathbb{E}[f(x)] = \int_{-\infty}^{\infty}p(x)f(x)dx$ where $p(x)$ is the probability of event $x$ occurring. So we have
and
Where the third line follows from the fact that $\nabla_{x}f(x) = f(x)\nabla_{x}\log(f(x))$. The fact that we have turned the gradient of our cost function $J$ into an expectation is good because that means we can estimate it by sampling data. The last piece of the puzzle is to figure out how to calculate $\nabla_{\theta}\log(\pi_{\theta}(\tau))$. Note that we can rewrite $\pi_{\theta}(\tau)$ as
Convince yourself that the above relation is true. $\pi_{\theta}(\tau)$ is the probability of trajectory $\tau$ happening. It is the probability of starting in $s_{1}$, then taking action $a_{1}$ given $s_{1}$, then transitioning to state $s_{2}$ given $a_{1}$ in $s_{1}$, and so on. This joint probability can be factored out. The last step is to realize $p(a_{t}|s_{t})$ is the definition of $\pi_{\theta}(a_{t}|s_{t})$. Now
This simplication is enough for us to completed our estimate of the policy gradient $\nabla_{\theta}J(\theta)$.
Where $N$ is just the number of episodes (analogous to epochs) we do. Having a set of $N$ trajectories and then averaging the policy gradient estimate over each of them makes this estimate more robust. Now that we can estimate the policy gradient, we simply would update our parameters in the familiar way
One interpretation of this result is that we are trying to maximize the log likelihood of trajectories that give good rewards and minimize the log likelihood of those that don’t. This is the idea behind the REINFORCE algorithm which is
1. sample $N$ trajectories by running the policy
2. estimate the policy gradient like above
3. update the parameters $\theta$
4. Repeat until converged
### Actor Critic
One issue with vanilla policy gradients is that its very hard to assign credit to state-action pairs that resulted in good reward because we only consider the total reward $\sum_{t=1}^{T}R(a_{t}, s_{t})$. The trajectories are noisy. But if we had the $Q$ function, we would know what state-action pairs were good. In other words, we would estimate the gradient of $J$ as
The idea of actor-critic is that we have an actor that samples trajectories using the policy, and a critic that critiques the policy using the $Q$ function. Since we don’t have the optimal $Q$ functions, we can estimate it like we did in deep Q learning. So we could have a policy network that takes in a state and returns a probability distribution over the action space (i.e. $\pi_{\theta}(a|s))$ and a $Q$ network that takes in a state-action pair and returns its Q value estimate. Let’s say this network is parameterized by a generic variable $\beta$. Note that these don’t have to be neural networks, but for the sake of this guide I’ll just say “network”. So we have networks $\pi_{\theta}$ and $Q_{\beta}$. The general actor-critic algorithm then goes like
1. Initialize $s, \theta, \beta$
2. Repeat until converged:
• Sample action $a$ from $\pi_{\theta}(\cdot|s)$
• Receive reward $r$ and sample next state $s’ \sim p(s’|s, a)$
• Use the critic to evaluate the actor and update the policy similar to like we did in policy gradients: $\theta \leftarrow \theta - \alpha\nabla_{\theta}\log(\pi_{\theta}(a|s))Q_{\beta}(s, a)$
• Update the critic according to some loss metric: $\text{MSE Loss} = (Q_{t+1}(s, a) - (r + \max_{a’}Q_{t}(s’, a’)))^{2}$
• Update $\beta$ using backprop or whatever update rule
Of course you can sample whole trajectories instead of one state-action pair at a time. Different types of actor-critic result from changing the “critic”. In REINFORCE, the critic was simply the reward we got from the trajectory. In actor-critic, the critic is the Q function. Another popular choice is called advantage actor-critic, in which the critic is the advantage functions
Where V is the value function (recall value iteration). The advantage function A tells us how much better is taking action $a$ in state $s$ than the expected cumulative reward of being in state $s$.
This concludes our discussion of RL for the Deep Learning section. In the future I will make more RL-related guides that focus on more advanced topics and current research. Feel free to reach out with any questions or if you notice something you think is inaccurate and I’ll do my best to respond! | {"extraction_info": {"found_math": true, "script_math_tex": 1, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8877618908882141, "perplexity": 261.4203750979743}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-29/segments/1593655911896.73/warc/CC-MAIN-20200710175432-20200710205432-00317.warc.gz"} |
http://noj.io/problem/p/1037/always-on-the-run | # Always On the Run
1000ms 65536K
6 3
Difficult
Description
Screeching tires. Searching lights. Wailing sirens. Police cars everywhere. Trisha Quickfinger did it again! Stealing the 'Mona Lisa' had been more difficult than planned, but being the world's best art thief means expecting the unexpected. So here she is, the wrapped frame tucked firmly under her arm, running to catch the northbound metro to Charles-de-Gaulle airport.
But even more important than actually stealing the painting is to shake off the police that will soon be following her. Trisha's plan is simple: for several days she will be flying from one city to another, making one flight per day. When she is reasonably sure that the police has lost her trail, she will fly to Atlanta and meet her 'customer' (known only as Mr. P.) to deliver the painting.
Her plan is complicated by the fact that nowadays, even when you are stealing expensive art, you have to watch your spending budget. Trisha therefore wants to spend the least money possible on her escape flights. This is not easy, since airlines prices and flight availability vary from day to day. The price and availability of an airline connection depends on the two cities involved and the day of travel. Every pair of cities has a 'flight schedule' which repeats every few days. The length of the period may be different for each pair of cities and for each direction.
Although Trisha is a good at stealing paintings, she easily gets confused when booking airline flights. This is where you come in.
Input
The input contains the descriptions of several scenarios in which Trisha tries to escape. Every description starts with a line containing two integers n and k. n is the number of cities through which Trisha's escape may take her, and k is the number of flights she will take. The cities are numbered 1, 2, ..., n, where 1 is Paris, her starting point, and n is Atlanta, her final destination. The numbers will satisfy 2 ≤ n ≤ 10 and 1 ≤ k ≤ 1000. Next you are given n(n - 1) flight schedules, one per line, describing the connection between every possible pair of cities. The first n - 1 flight schedules correspond to the flights from city 1 to all other cities (2, 3, ..., n), the next n - 1 lines to those from city 2 to all others (1, 3, 4, ..., n), and so on.
The description of the flight schedule itself starts with an integer d, the length of the period in days, with 1 ≤ d ≤ 30. Following this are d non-negative integers, representing the cost of the flight between the two cities on days 1, 2, ..., d. A cost of 0 means that there is no flight between the two cities on that day.
So, for example, the flight schedule "3 75 0 80" means that on the first day the flight costs 75, on the second day there is no flight, on the third day it costs 80, and then the cycle repeats: on the fourth day the flight costs 75, there is no flight on the fifth day, etc.
The input is terminated by a scenario having n = k = 0.
Output
For each scenario in the input, first output the number of the scenario, as shown in the sample output. If it is possible for Trisha to travel k days, starting in city 1, each day flying to a different city than the day before, and finally (after k days) arriving in city n, then print "The best flight costs x.", where x is the least amount that the k flights can cost.
If it is not possible to travel in such a way, print "No flight possible.".
Print a blank line after each scenario.
Sample Input
3 6
2 130 150
3 75 0 80
7 120 110 0 100 110 120 0
4 60 70 60 50
3 0 135 140
2 70 80
2 3
2 0 70
1 80
0 0
Sample Output
Scenario #1
The best flight costs 460.
Scenario #2
No flight possible.
Source
Editor
on 2006-10-02 16:49:16 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.15417057275772095, "perplexity": 1356.864159501341}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-26/segments/1529267864148.93/warc/CC-MAIN-20180621114153-20180621134153-00373.warc.gz"} |
https://www.microscopyu.com/gallery-images/indian-muntjac-cells-with-lysotracker-2 | # Indian Muntjac Cells with LysoTracker
### UV-2B Longpass Emission (Wide Bandwidth Excitation) Ultraviolet Set
Fluorescence emission intensity from a culture of Indian Muntjac deerskin fibroblast cells adherent on a cover glass. Nuclei in the cells were targeted with the nucleic acid probe SYTOX Green, which has an excitation maximum at 504 nanometers and an emission maximum at 523 nanometers when bound to DNA in cultured cells and tissue sections. In addition, the cells were stained with LysoTracker Blue DND-22 (targeting lysosomes; excitation at 373 nanometers and emission at 422 nanometers) and Alexa Fluor 568 phalloidin (targeting actin; excitation at 578 nanometers and emission at 600 nanometers). Note the presence of signal from both the red and green fluorophores in the image above. In addition, the image displays increased contrast and a darker background when compared to images captured with the related Nikon longpass UV-2A filter combination. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8891305923461914, "perplexity": 7212.113182804562}, "config": {"markdown_headings": true, "markdown_code": false, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-16/segments/1585371665328.87/warc/CC-MAIN-20200407022841-20200407053341-00276.warc.gz"} |
http://forum.symthic.com/battlefield-1-general-discussion/11145-in-the-name-of-the-tsar-expansion-confirmed-information-and-speculation/index21.html?s=671898971b88598e5313ba08cdd2d3675d1358de | Welcome to symthic forums! We would love if you'd register!
You don't have to be expert in bit baking, everyone is more than welcome to join our community.
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## "In the Name of the Tsar" Expansion: Confirmed Information and Speculation
Hey! If this is your first visit on symthic.com, also check out our weapon damage charts.
Currently we have charts for Battlefield 3, Call of Duty: Black Ops 2, Medal of Honor: Warfighter and Call of Duty: Modern Warfare 3
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Friday, July 7th 2017, 7:09am
### Quoted from "CReaperDorian"
In the world of the metallic cartridge, it is silly. However, back when cap-and-ball revolvers were still in common use, carrying extra loaded cylinders wouldn't have been a bad idea (assuming the revolver had relatively fast and easy disassembly and reassembly). DICE must have gotten this idea from old cap-and-ball revolvers, me thinks.
I remember seeing a Western years and years ago where the protagonist did exactly this, had like four spare cylinders on him and swapped them out. (Edit: Pale Rider was the one, I finally know the name now)
As for how practical it is in BF1, we don't have the reload times yet but I'm gonna go out on a limb and say that the empty cylinder swap reload is going to be notably faster than the six-round (one remaining) reload.
Who Enjoys, Wins
This post has been edited 1 times, last edit by "BleedingUranium" (Jul 7th 2017, 7:20am)
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Friday, July 7th 2017, 7:52am
Yeah, it'll likely be faster. Although, I must say that if DICE is that concerned about the revolver's reload speed, they could have implemented the 1910 model with a swing-out cylinder. Of course, the Nagant M1895 is the iconic model and the one that actually saw use (the 1910 models are almost certainly unicorns today).
### Spoiler
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Tuesday, July 18th 2017, 8:24am
Double-post bump update!
Bumpdate?
Uri is seemingly correct about the amount of actual new guns, thankfully. The Maxim SMG, General Liu Rifle, Perino M1908, Vetterli M1870, and Obrez have been supposedly "leaked" via the CTE.
This post has been edited 2 times, last edit by "CReaperDorian" (Jul 18th 2017, 8:31am)
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Tuesday, July 18th 2017, 9:40am
What leaks do you speak of?
Another high capacity SMG? Reddit will be unbearable for a few weeks after its release lol.
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Tuesday, July 18th 2017, 2:13pm
### Quoted from "CReaperDorian"
Uri is seemingly correct about the amount of actual new guns, thankfully. The Maxim SMG, General Liu Rifle, Perino M1908, Vetterli M1870, and Obrez have been supposedly "leaked" via the CTE.
If that's the case, then I count one SMG for assault (the maxim SMG), one SLR for medic (General Liu Rifle), one LMG for support (Perino M1908 ) and one BA for scout (Vetterli M1870). I could see Obrez, as it is a sawed off bolt action rifle, go to scout; be used as a pistol; or even perhaps another tanker/pilot weapon (god, I hope not). My running theory was that one main class would get one additional weapon for every DLC (after assault got two new weapons in TSNP), that a different other main class would get an extra weapon in this update, and then another class would get an extra weapon in the next update, and so on. So, after all the DLCs, all classes would have an equal number of weapons, but depending on what they do with the Obrez, that complicates my theory.
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Tuesday, July 18th 2017, 2:29pm
### Quoted from "dwojtk"
My running theory was that one main class would get one additional weapon for every DLC (after assault got two new weapons in TSNP), that a different other main class would get an extra weapon in this update, and then another class would get an extra weapon in the next update, and so on. So, after all the DLCs, all classes would have an equal number of weapons, but depending on what they do with the Obrez, that complicates my theory.
That might quite possibly have been the original plan, but it seems at some point DICE decided to add a lot more content to this DLC, so we're getting extra maps and likely more weapons as well.
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Tuesday, July 18th 2017, 4:50pm
### Quoted from "dwojtk"
My running theory was that one main class would get one additional weapon for every DLC (after assault got two new weapons in TSNP), that a different other main class would get an extra weapon in this update, and then another class would get an extra weapon in the next update, and so on. So, after all the DLCs, all classes would have an equal number of weapons, but depending on what they do with the Obrez, that complicates my theory.
That might quite possibly have been the original plan, but it seems at some point DICE decided to add a lot more content to this DLC, so we're getting extra maps and likely more weapons as well.
Well it's kinda obvious that these weapons were selected prior to the original plan even being in place before they expanded the DLC. I have a hunch some of these weapons were intended for Turning Tides or even Apocalypse, heck they could have been slated for free content updates. I just know that they didn't scramble last minute to pick all the extra Tsar weapons to model, animate, and balance; it seems the devs are pooling content that was previously meant for implementation later on.
To Aim Assist or not to Aim Assist, that is the question.
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### Quoted from "Zer0Cod3x"
the Sebstalder is quiet good since it can 3hit kill at any distanc ,but In my opinion i actually thikn the sweeper is better, its got a really really fast firerate that can beat alll those Noobmaticos, Helregall adn shitguns in close quarters , and its also really accurate out to like l;ong range,. overall great allround gun, jsut my 2\$ tho
### My "Contributions"
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Tuesday, July 18th 2017, 4:57pm
Qu
### Quoted from "CReaperDorian"
Uri is seemingly correct about the amount of actual new guns, thankfully. The Maxim SMG, General Liu Rifle, Perino M1908, Vetterli M1870, and Obrez have been supposedly "leaked" via the CTE.
If that's the case, then I count one SMG for assault (the maxim SMG), one SLR for medic (General Liu Rifle), one LMG for support (Perino M1908 ) and one BA for scout (Vetterli M1870). I could see Obrez, as it is a sawed off bolt action rifle, go to scout; be used as a pistol; or even perhaps another tanker/pilot weapon (god, I hope not). My running theory was that one main class would get one additional weapon for every DLC (after assault got two new weapons in TSNP), that a different other main class would get an extra weapon in this update, and then another class would get an extra weapon in the next update, and so on. So, after all the DLCs, all classes would have an equal number of weapons, but depending on what they do with the Obrez, that complicates my theory.
Quite an interesting selection, where exactly did this leak? Cannot find it.
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Tuesday, July 18th 2017, 8:48pm
### Quoted from "CReaperDorian"
Double-post bump update!
Bumpdate?
Uri is seemingly correct about the amount of actual new guns, thankfully. The Maxim SMG, General Liu Rifle, Perino M1908, Vetterli M1870, and Obrez have been supposedly "leaked" via the CTE.
I'd love to know where the leak came from, I can't find anything on reddit, but these all look really interesting. Edit: The only other person I can seem to find who knows about them is this German Youtuber, but I can't understand more than a few words here and there, so no idea on source. I'd expect they're in the game files in some way, but I'm just surprised no one else is talking about them.
I'm so happy the Maxim SMG is in, that adorable chibi belt-fed MG. 9x19mm (same as MP 18 ) with an 80-round capacity, fed from 8 seperate M1909 Hotchkiss style strip-clips each holding 10 rounds, all automatically fed into the gun one after each other. And presumably replaced one at a time as well. No idea on RoF, but this gun should definitely prove interesting.
The General Liu rifle looks interesting as well, and being chambered in 7.92x57mm (M1916, Mondragon, M1906) with a six-round capacity; it looks like we have a partner-rifle for the M1906. Interesting to see a Chinese weapon in here too.
The Perino Model 1908 finally gives us an Italian MG, as well as an MG that looks remarkably similar to the iconic Maxim family. Firing 6.5x52mm (Cei-Rigotti, but won't share damage model) at 450rpm, using 25-round "strip clips" like the M1909 Hotchkiss, it should be rather comparable to that gun. It should be noted that, as far as I can tell with a quick search, it never had a stock.
The Vetterli M1870 gives us an Italian bolt action, and could go three different ways depending on how they want to do it. The original was chambered in 10.4x47mmR and was single shot, making it a potential Martini-Henry partner-weapon. However, it wasn't long before they were modified to have four-round magazines, so in that form maybe somewhere between the Martini and "normal" BAs. And then there's a third version, updated in 1915, firing 6.5x52mm (Cei-Rigotti and Perino, again not same damage model) with a six-round magazine. I suspect the final, 6.5mm Carcano version is the most likely to appear.
The Obrez is very obviously a Mosin-Nagant Carbine for Tanker/Pilot, just as every other Tanker/Pilot weapon is a shorter/longer version of an existing primary (except the Pieper). This also almost rounds out the Carbine selection, giving us a Shotgun (M1900), SMG (Stop Auto), SLR (Pieper), and Bolt Action (Obrez), leaving only an LMG.
Who Enjoys, Wins
This post has been edited 1 times, last edit by "BleedingUranium" (Jul 18th 2017, 9:00pm)
thank mr skeltal
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Tuesday, July 18th 2017, 10:43pm
Interesting collection of weapons, I figured we would get Liu's Rifle and the Maxim SMG at some point but the Vetterli M1870 and Perino M1908 caught me off guard.
I feel like the Rolling Block would have been better than a single shot Vetterli and the Carcano makes more sense as a six shot rifle, I hope this means it will get the 4 round box mag and be a high capacity black powder rifle.
I'm not sure how I feel about the Perino, on one hand it looks badass but I can't figure out how you would fire it standing let alone aim down sights thanks to its trigger placement.
This image is probably what inspired DICE to make it a primary but the trigger is on the back of the gun so this guy is doing nothing but hold the gun in a cool way.
EDIT: I guess you could fire it in the way this guy is firing a St. Etienne
I swear to god if the Obrez is a Carbine I will be pissed(unless DICE wants to make Carbines all class primaries at some point). | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.3277331590652466, "perplexity": 10770.95008153823}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-43/segments/1539583512592.60/warc/CC-MAIN-20181020055317-20181020080817-00010.warc.gz"} |
https://brilliant.org/problems/a-problem-by-swapnil-yadav/ | # A problem by Swapnil Yadav
Level pending
f(x) is a polynomial function such that f(f(1))=2 . There exists no real roots of f(x). then f(2) equals
× | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8469597101211548, "perplexity": 4049.4177120761383}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 5, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-44/segments/1476988719045.47/warc/CC-MAIN-20161020183839-00385-ip-10-171-6-4.ec2.internal.warc.gz"} |
https://forum.allaboutcircuits.com/threads/initial-conditions-of-switched-circuits.44252/ | # Initial Conditions of Switched Circuits
Discussion in 'Homework Help' started by jegues, Oct 14, 2010.
1. ### jegues Thread Starter Well-Known Member
Sep 13, 2010
735
45
See figure for question and my attempt.
I redrew the circuit at a time just before time 0.
Doing a KVL in loop 1, 2 and 3 I concluded that V1(0-) = 24V. I'm not 100% confident about this result, is it correct? If not, how do I go about finding V1(0-)?
I redrew the circuit again at a time just after time 0.
I have no clue how I'm suppose to find I2(0+) and V1(0+) here. Can someone get me started?
Thanks again!
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• ###### 7.8-7A1P2.JPG
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2. ### t_n_k AAC Fanatic!
Mar 6, 2009
5,448
790
V1(0-) won't be 24V.
The circuit has stabilized before t=0.
At this time ...
The inductor will look like a short and the capacitor will charge to a value determined by the voltage divider formed by the 24V supply and the series combination of the 20Ω and 80Ω resistors. The value of V1 and the capacitor voltage will be the same, since there will be no steady state voltage drop across the inductor.
3. ### t_n_k AAC Fanatic!
Mar 6, 2009
5,448
790
For the t=0+ case one approach is to treat the inductor as a current source and the capacitor as a voltage source - just for that instant. Then say apply superposition (or whatever method suits you) to find the unknown quantities.
The notional current source value will be the steady state inductor current at t=0-.
This approach only works because you are only required to solve for values at the instant the switch closes.
4. ### jegues Thread Starter Well-Known Member
Sep 13, 2010
735
45
Okay so my BIG mistake was that I interpreted/read the question wrong.
The circuit is already at steady state when the switch closes. So at t(0-) my capacitor and inductor should be their steady state equivalents respectively. (Open circuit, short circuit)
Then once the switch closes, t(0+), I can model my capacitor and inductor accordingly.
I'm going to try this problem again from scratch and I'll post my results!
Thanks again tnk, your help is always appreciated!
5. ### jegues Thread Starter Well-Known Member
Sep 13, 2010
735
45
UPDATE: I've reattempted the problem and came up with a final solution.
See the figures attached for my 2nd attempt at this problem.
Okay so basically what I did was I redrew the correct circuits for t(0-) and t(0+).
In the t(0-) circuit I solved for V1(0-) using a voltage divider as tnk mentioned, and clearly one can see that i2(0-) is 0.
I also obtained Vc and Il.
Then I went to my t(0+) circuit and applied mesh analysis. From these results I was able to solve for V1(0+) and i2(0+).
Does anyone see any errors in my work/results?
I'm really hoping I finally got this one down! Let me know what you think!
Thanks again!
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6. ### Jony130 AAC Fanatic!
Feb 17, 2009
4,511
1,272
I to check you result for V1(0+) write this nodal equation
$240mA = \frac{V1}{80} - \frac{(24V - V1) }{80}$
And when I solve this I get this result for V1(0+)
V1(0+) = 21.6V
Your mesh equation is not correct becaues of a current source in the circuit
7. ### jegues Thread Starter Well-Known Member
Sep 13, 2010
735
45
Okay I agree that my mesh equation must be wrong, but I'm not sure where exactly I went wrong. Can you see it? I don't see how the current source is causing any problems.
EDIT: I found my mistake. I had an algebra error in my equation *,
It should be,
$160i_{2} = 4.8 \rightarrow i_{2} = 0.03A$
Then one will find that,
$V_{1}(0+) = 21.6V$
Last edited: Oct 15, 2010
8. ### Jony130 AAC Fanatic!
Feb 17, 2009
4,511
1,272
good job, but for this circuit the nodal analysis is much faster.
9. ### jegues Thread Starter Well-Known Member
Sep 13, 2010
735
45
Yup I realize that now, but if I didn't notice it at the time. I need more practice I guess...
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1,082 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 4, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8225487470626831, "perplexity": 3125.499527076578}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-51/segments/1544376824822.41/warc/CC-MAIN-20181213123823-20181213145323-00099.warc.gz"} |
https://infoscience.epfl.ch/record/198080 | Infoscience
Journal article
# Impact of Annealing on the Early Hydration of Tricalcium Silicate
It was recently proposed that the induction period observed during the hydration of tricalcium silicate could be explained by the build-up of ions in solution. Due to the importance of defects in this mechanism, this work describes the effect of different annealing effects on the defect structure and hydration behavior of C3S. The impact of annealing on the crystal structure was checked by X-ray diffraction and the defect structure studied by transmission electron microscopy. The hydration kinetics were followed by isothermal calorimetry of pastes. Scanning electron microscopy was used to look at the microstructure formation. It was observed that grinding created a highly deformed layer on the surface of the grains, which disappeared after annealing. The defect structure was closely related to the length of the induction period observed in pastes by calorimetry. There was no observable effect on the morphology of C-S-H during hydration, but the number of calcium hydroxide nuclei was less in pastes from annealed material. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9463725090026855, "perplexity": 2035.1795297044976}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-05/segments/1516084886792.7/warc/CC-MAIN-20180117003801-20180117023801-00001.warc.gz"} |
http://www.r-bloggers.com/our-friend-the-age-earnings-profile/ | # Our Friend the Age-Earnings Profile
March 7, 2011
By
(This article was first published on Back Side Smack » R Stuff, and kindly contributed to R-bloggers)
I like Labor Economics. Partially because it has a nice mix of theory and practical empiricism, but mostly because it seems to be a sub-field with a number of agreed upon stylized facts that grow not out of micro theory but out of hundreds of empirical studies. One of those facts is the age-earnings profile [PDF]. Basically, as individuals age they experience relatively rapid wage growth in their 20s and 30s and slowing wage growth in their 40s and 50s. There is quite a bit of discussion over what causes the age earnings profile. Internal labor markets, growth of human capital, employee matches, etc. There are a number of competing theories and not all of them are mutually exclusive. But the profile itself is pretty robust.
What does the profile look like?
From AEP
Above is a scatterplot of log earnings per hour against age. It was drawn from a small sub-sample of the March 2002 Current Population Survey (Basically New England + NY, NJ and PA). Education in this sub-sample was coded as “college” or “high school” with dropouts from either removed from the sample, so we don’t get a true age-earnings profile. A true profile would subtract years of education (and some number like 5-6 for years between birth and education starting) from age to get a measure of experience. But you can see the basic shape of the age earnings profile in the plot. A slight increase in the average log earnings over the first 10-20 years in the workforce, then a flattening of the earnings curve. I have not actually plotted a regression of log earnings on wage, but we could. We could certainly fit a linear regression, but we would see a big relationship between age and the residuals (giving us the impression that a linear fit doesn’t capture the data). We could also add a quadratic term into the linear regression (e.g. lm(log(earnings) ~ age + I(age^2))) or we could use a spline term in the regression.
One thing to consider when determining the form of regression is other control variables. On this same dataset, we can see the distribution of earnings among high school and college graduates:
From AEP
The distributions are not conditional on age, race or sex, but we can see a great deal more variation on earnings among college graduates than high school graduates. So we could also imagine that the AEP would be shaped somewhat differently for college graduates. There are a few reasons why this might be. First of all, high school graduates are probably more likely to be involved in hourly work rather than salaried work and measuring hourly wages is probably much more accurate than imputing an hourly wage from salary information. I would also imagine that since high school graduate earnings are lower they also are more likely to face binding lower constraints (minimum wage laws, etc.) and might vary less. Either way we can expect to see a different shape among high school graduates than among college graduates.
Code for this post is below. It includes a lot more than the above graph because it was part of a homework assignment. Some of the code is cool (especially converting binary factors to single columns with levels), but most of it is housekeeping.
R-bloggers.com offers daily e-mail updates about R news and tutorials on topics such as: visualization (ggplot2, Boxplots, maps, animation), programming (RStudio, Sweave, LaTeX, SQL, Eclipse, git, hadoop, Web Scraping) statistics (regression, PCA, time series, trading) and more... | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.15434911847114563, "perplexity": 1511.4235225518353}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-48/segments/1386163056120/warc/CC-MAIN-20131204131736-00010-ip-10-33-133-15.ec2.internal.warc.gz"} |
http://physics.aps.org/articles/v4/70 | # Viewpoint: Surface nanobubbles or Knudsen bubbles?
, Department of Applied Mathematics, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200, Australia
Published September 6, 2011 | Physics 4, 70 (2011) | DOI: 10.1103/Physics.4.70
#### Knudsen Gas Provides Nanobubble Stability
James R. T. Seddon, Harold J. W. Zandvliet, and Detlef Lohse
Published September 6, 2011 | PDF (free)
The mysterious stability of nanobubbles on surfaces is a puzzle baffling soft matter and colloid scientists. Bubbles inside a fluid tend to be spherical, but surface bubbles have the appearance of blisters with typical widths of $1000$ nanometers (nm) and heights of $20\phantom{\rule{0.333em}{0ex}}\text{nm}$. The existence of surface bubbles was proposed to explain the extremely long range and the magnitude of the strongly attractive forces observed between hydrophobic surfaces in water [1]. Nanobubbles are of interest because they are easily produced and are stable, and as such, their presence may be altering many aqueous interfaces and exerting influence on processes as diverse as froth flotation to the transportation of anticancer drugs across membranes. Classically, bubbles will deflate, leading to an increase in Laplace pressure (the pressure differential inside and outside a bubble) and a positive feedback loop that results in their rapid disappearance. However, surface nanobubbles, seemingly unaware of the rules, can remain stable for days. Now, writing in Physical Review Letters, James Seddon and coauthors [2] at the University of Twente, the Netherlands, have proposed an explanation for this stability, whereby the properties of the gas within a nanobubble generate a recirculation of the surrounding liquid, which effectively ensures that the gas escaping the bubble through diffusion is recaptured and the bubble lifetime is extended.
The existence of surface nanobubbles was confirmed through atomic force microscope images, produced by groups in China [3] and Japan [4]. The Chinese group, led by Jun Hu, demonstrated that the creation of nanobubbles on a hydrophobic surface could be induced through a technique known as solvent exchange. Typically, the solvents employed are water and ethanol, which are miscible. When water displaces ethanol, a pure ethanol phase momentarily wets the surface before diffusing into the water. In doing so, excess gas is left behind at the interface and spherical cap nanobubbles are formed, with heights typically $<100\phantom{\rule{0.333em}{0ex}}\text{nm}$ and widths up to $10$ microns. For their part, the Japanese group of Ishida and Higashitani showed that the process of immersing a hydrophobic surface in water leads to incomplete wetting and the production of nanobubbles. Nanobubbles can also be produced by electrolysis and temperature change. As ethanol is often employed in cleaning regimes and the temperature changes required to induce nanobubbles are small ($<10$ °$\text{C}$), it can be seen that nanobubbles may be present in a great many circumstances. Additionally, AFM studies reveal that the contact angle of nanobubbles is significantly higher (as measured through the more dense aqueous phase) than microscopic bubbles and that stability is largely unaffected by pH, electrolytes, and surfactants. The stability of nanobubbles has been a central question since they were first suggested. So what is the source of this surprising stability? We must consider two scenarios, both of which, at first glance, appear unlikely: either gas is not leaving the bubble, or it is leaving the bubble, but it is being replaced at approximately the same rate.
Even the purest of solutions contain quantities of insoluble material. William Ducker proposed that this insoluble material accumulates at the surface of nanobubbles, and in doing so, decreases the surface tension and thereby the Laplace pressure [5]. This would also alter the contact angle. From experiments, we now know that nanobubbles become unstable at high surfactant concentrations. The inference is that the stabilizing material is transported from the nanobubble surface to the surfactant micelles by the detergent action of the surfactant. An alternative explanation is that the oil-like interior of a micelle is a sink for gas molecules and the resulting increase in gas solubility leads to the disappearance of nanobubbles.
The Twente group has investigated the second scenario, that is, diffusion out of nanobubbles is occurring, but a dynamic equilibrium exists such that gas molecules return to the nanobubble and long term stability results [6]. The development of these ideas over several years has led to the current work. The most recent advance assumes that nanobubbles are so small that in most cases a gas molecule passing from one side to the other will do so without colliding with another gas molecule. Such a gas is called a Knudsen gas. The Twente group argues that gas molecules within the nanobubble have a net flow towards the gas-liquid interface (see Fig. 1) due to the difference between the surface facing out and that facing the fluid, and that the collisions that would normally randomize such a flow do not take place in a Knudsen gas. As molecules dissolve into the liquid, the momentum transfer leads to a circulating flow in the liquid near the interface that returns the gas molecules to the substrate, and ultimately, the nanobubble. The energy required to drive this flow is small and can be supplied thermally by the substrate over the timescale that nanobubbles are observed. The team also provides force measurements taken above a nanobubble as evidence of this flow. Of course, this theory is predicated on the gas being a Knudsen gas. When bubbles exceed a certain height (calculated to be $\sim 100\phantom{\rule{0.333em}{0ex}}\text{nm}$), the Knudsen conditions are no longer met and the mechanism ceases to operate. Hence acceptance of this theory would rightly lead to nanobubbles at surfaces becoming known as “Knudsen bubbles.”
Complicating the case for this mechanism are reports that nanobubbles are also stable in bulk solution. The group of To Ngai in Hong Kong uses nanobubbles to induce a depletion force that is measured by total internal reflection microscopy [7], and recently, Ohgaki and co-workers in Osaka have shown images of bulk nanobubble replicas obtained using freeze fracture, and they report that nanobubble lifetime extends to two weeks [8]. Such bubbles cannot be stabilised by the Knudsen bubble model, which is dependent on the symmetry-breaking effect of the surface. However, the alternative explanation of Ducker [5] can still be applied to bulk nanobubbles. Hence, for these and other reasons, the nanobubble community is eagerly anticipating independent verification of bulk nanobubbles.
Another challenge to the Twente model is the observation of a gas phase at surfaces with an altogether different morphology. Known as “micropancakes” because of their shape [9], these gas phases extend large distances laterally but are only a few nanometers high. Their upper surface is parallel with the substrate. Furthermore, they can coexist with nanobubbles, and nanobubbles are even observed on top of micropancakes. The recognition that nanobubbles and other gaseous objects are stable challenges our understanding and requires that we consider the role they may be playing in many processes. This work defines an upper bound for the height of nanobubbles and connects the surprisingly high contact angles between the bubble and the surface, exhibited by nanobubbles, to their stability. The Twente group theorizes that the bubble is filled with a so-called Knudsen gas, which is so dilute that the mean free path is larger than the containing vessel, or in this case, bubble. As such, the very small size of surface nanobubbles—or Knudsen bubbles—may be the source of their stability rather than the cause of their disappearance.
### References
1. J. L. Parker, P. M. Claesson, and P. Attard, J. Phys. Chem. 98, 8468 (1994).
2. J. R. T. Seddon, H. J. W. Zandvliet, and D. Lohse, Phys. Rev. Lett. 107, 116101 (2011).
3. S. T. Lou Z. Q. Ouyang, Y. Zhang, X. J. Li, J. Hu, M. Q. Li, and F. J. Yang, J. Vac. Sci. Technol. B 18, 2573 (2000).
4. N. Ishida, T. Inoue, M. Miyahara, and K. Higashitani, Langmuir 16, 6377 (2000).
5. W. A. Ducker, Langmuir 25, 8907 (2009).
6. M. P. Brenner and D. Lohse, Phys. Rev. Lett 101, 214505 (2008).
7. F. Jin, X. J. Gong, J. Ye, and T. Ngai, Soft Matter 4, 968 (2008).
8. K. Ohgaki, N. Q. Khanh, Y. Joden, A. Tsuji, and T. Nakagawa, Chem. Eng. Sci. 65, 1296 (2010).
9. X. H. Zhang, X. D. Zhang, J. L. Sun, Z. X. Zhang, G. Li, H. P. Fang, X. D. Xiao, X. C. Zeng, and J. Hu, Langmuir 23, 1778 (2007).
### About the Author: Vincent S. J. Craig
Vince Craig is Head of the Department of Applied Mathematics at the Australian National University (ANU) in the Research School of Physics and Engineering. He completed both his B.Sc. (chemistry, 1993) and Ph.D. degrees (Research School of Physics, 1997) at the ANU before postdoctoral positions at the University of California, Davis, and the University of Newcastle, New South Wales. He is currently the recipient of an ARC Future Fellowship on the topic of specific ion effects. His other research interests include the direct measurement of surface forces, both quasistatic and dynamic, interfacial adsorption of surfactants and polymers, bubble coalescence in electrolyte solutions, and nanobubbles. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 7, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7490290403366089, "perplexity": 2118.293326253089}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-52/segments/1418802771374.156/warc/CC-MAIN-20141217075251-00005-ip-10-231-17-201.ec2.internal.warc.gz"} |
http://mathhelpforum.com/calculus/214920-rate-change-problem-print.html | rate of change problem
• Mar 17th 2013, 01:40 AM
asifrahman1988
rate of change problem
Alabama Instruments Company has set up a production line to manufacture a new calculator. The rate of production of these calculators after t weeks is
dx
dt = 5000(1−(100/(t+10)^2)) calculators per week.
(Notice that production approaches 5000 per week as time goes on, but the initial production is lower because ot the workers’ unfamiliarity with the new techniques.) Find the number of calculators produced from the beginning of the third week to the end of the fourth week
• Mar 17th 2013, 02:40 AM
Prove It
Re: rate of change problem
Your equation is $\displaystyle \frac{dx}{dt} = 5000 \left( 1 - \frac{100}{(t + 10)^2} \right)$.
Rewrite this as $\displaystyle \frac{dx}{dt} = 5000 - 500\,000(t + 10)^{-2}$ and integrate. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 2, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.740570604801178, "perplexity": 2305.093280509658}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-26/segments/1498128320869.68/warc/CC-MAIN-20170626221252-20170627001252-00037.warc.gz"} |
https://www.hepdata.net/search/?q=&collaboration=HERMES&sort_order=&page=1&sort_by=latest | Showing 19 of 19 results
#### Transverse-target-spin asymmetry in exclusive $\omega$-meson electroproduction
The collaboration Airapetian, A. ; Akopov, N. ; Akopov, Z. ; et al.
Eur.Phys.J. C75 (2015) 600, 2015.
Inspire Record 1391139
Hard exclusive electroproduction of $\omega$ mesons is studied with the HERMES spectrometer at the DESY laboratory by scattering 27.6 GeV positron and electron beams off a transversely polarized hydrogen target. The amplitudes of five azimuthal modulations of the single-spin asymmetry of the cross section with respect to the transverse proton polarization are measured. They are determined in the entire kinematic region as well as for two bins in photon virtuality and momentum transfer to the nucleon. Also, a separation of asymmetry amplitudes into longitudinal and transverse components is done. These results are compared to a phenomenological model that includes the pion pole contribution. Within this model, the data favor a positive $\pi\omega$ transition form factor.
4 data tables
The amplitudes of the five sine and two cosine modulations as determined in the entire kinematic region. The results receive an additional 8.2% scale uncertainty corresponding to the target-polarization uncertainty.
The definition of intervals and the mean values of the kinematic variables.
Results on the kinematic dependences of the five asymmetry amplitudes $A_{UT}$ and two amplitudes $A_{UU}$. The first two columns correspond to the $-t'$ intervals $0.00 - 0.07 - 0.20$ GeV$^2$ and the last two columns to the $Q^{2}$ intervals $1.00 - 1.85 - 10.00$ GeV$^2$. The results receive an additional 8.2% scale uncertainty corresponding to the target-polarization uncertainty.
More…
#### Spin density matrix elements in exclusive $\omega$ electroproduction on $^1$H and $^2$H targets at 27.5 GeV beam energy
The collaboration Airapetian, A. ; Akopov, N. ; Akopov, Z. ; et al.
Eur.Phys.J. C74 (2014) 3110, 2014.
Inspire Record 1305286
Exclusive electroproduction of $\omega$ mesons on unpolarized hydrogen and deuterium targets is studied in the kinematic region of $Q^2> 1.0$ GeV$^2$ , 3.0 GeV $< W <$ 6.3 GeV, and $-t'< 0.2$ GeV$^2$ . Results on the angular distribution of the $\omega$ meson, including its decay products, are presented. The data were accumulated with the HERMES forward spectrometer during the 1996–2007 running period using the 27.6 GeV longitudinally polarized electron or positron beam of HERA. The determination of the virtual-photon longitudinal-to-transverse cross-section ratio reveals that a considerable part of the cross section arises from transversely polarized photons. Spin density matrix elements are presented in projections of $Q^2$ or $-t'$ . Violation of $s$ -channel helicity conservation is observed for some of these elements. A sizable contribution from unnatural-parity-exchange amplitudes is found and the phase shift between those amplitudes that describe transverse $\omega$ production by longitudinal and transverse virtual photons, $\gamma ^{*L} \rightarrow \omega _{T}$ and $\gamma ^{*T} \rightarrow \omega _{T}$ , is determined for the first time. A hierarchy of helicity amplitudes is established, which mainly means that the unnatural-parity-exchange amplitude describing the $\gamma ^*_T \rightarrow \omega _T$ transition dominates over the two natural-parity-exchange amplitudes describing the $\gamma ^*_L \rightarrow \omega _L$ and $\gamma ^*_T \rightarrow \omega _T$ transitions, with the latter two being of similar magnitude. Good agreement is found between the HERMES proton data and results of a pQCD-inspired phenomenological model that includes pion-pole contributions, which are of unnatural parity.
9 data tables
The 23 unpolarized and polarized $\omega$ SDMEs from the proton and deuteron data.
The 23 unpolarized and polarized $\omega$ SDMEs for the proton data in $Q^2$ intervals: $1.00 - 1.57 - 2.55 - 10.00$ GeV$^2$.
The 23 unpolarized and polarized $\omega$ SDMEs for the proton data in $-t'$ intervals: $0.000 - 0.044 - 0.105 - 0.200$ GeV$^2$.
More…
#### Inclusive Measurements of Inelastic Electron and Positron Scattering from Unpolarized Hydrogen and Deuterium Targets
The collaboration Airapetian, A. ; Akopov, N. ; Akopov, Z. ; et al.
JHEP 1105 (2011) 126, 2011.
Inspire Record 894309
3 data tables
Results on the differential Born cross section $\frac{d^2\sigma^p}{dx\,dQ^2}$ and $F_2^p$. The statistical uncertainty $\delta_{stat.}$ and the systematic uncertainties $\delta_{PID}$ (particle identification), $\delta_{model}$ (model dependence outside the acceptance), $\delta_{mis.}$ (misalignment), and $\delta_{rad.}$ (Bethe-Heitler efficiencies) are given in percent. Corresponding $x$ bin numbers and $Q^2$ bin numbers and the average values $\langle x \rangle$ and $\langle {Q^2} \rangle$ are listed in the first four columns. The overall normalization uncertainty is 7.6 %. The structure function $F_2^p$ is derived using the parameterization $R=R_{1998}$.
Results on the differential Born cross section $\frac{d^2\sigma^d}{dx\,dQ^2}$ and $F_2^d$. The statistical uncertainty $\delta_{stat.}$ and the systematic uncertainties $\delta_{PID}$ (particle identification), $\delta_{model}$ (model dependence outside the acceptance), $\delta_{mis.}$ (misalignment), and $\delta_{rad.}$ (Bethe-Heitler efficiencies), are given in percent. Corresponding $x$ bin numbers and $Q^2$ bin numbers and the average values $\langle x \rangle$ and $\langle{Q^2}\rangle$ are listed in the first four columns. The overall normalization uncertainty is 7.5 %. The structure function $F_2^d$ is derived using the parameterization $R=R_{1998}$.
Results on the inelastic Born cross-section ratio ${\sigma^d}/{\sigma^p}$. The statistical uncertainty $\delta_{stat.}$, the systematic uncertainty $\delta_{rad.}$ due to radiative corrections and $\delta_{model}$ due to the model dependence outside the acceptance are given in percent. The average values of $x$ and $Q^2$ are listed in the first two columns. The overall normalization uncertainty is 1.4$\%$.
#### Measurement of the virtual-photon asymmetry $A_2$ and the spin-structure function $g_2$ of the proton
The collaboration Airapetian, A. ; Akopov, N. ; Akopov, Z. ; et al.
Eur.Phys.J. C72 (2012) 1921, 2012.
Inspire Record 1082840
4 data tables
The spin-structure function $xg_2(x,Q^2)$ and virtual-photon asymmetry $A_2(x,Q^2)$ of the proton in bins of $(x,Q^2)$, see text for details. Statistical and systematic uncertainties are presented separately.
The spin-structure function $xg_2$ and the virtual-photon asymmetry $A_2$ of the proton after evolving to common $Q^2$ and averaging over in each $x$-bin (see text for details). Statistical and systematic uncertainties are presented separately.
Correlation matrix for $xg_2$ in 9 $x$-bins (as in Table 2).
More…
#### Multiplicities of charged pions and kaons from semi-inclusive deep-inelastic scattering by the proton and the deuteron
The collaboration Airapetian, A. ; Akopov, N. ; Akopov, Z. ; et al.
Phys.Rev. D87 (2013) 074029, 2013.
Inspire Record 1208547
Multiplicities in semi-inclusive deep-inelastic scattering are presented for each charge state of \pi^\pm and K^\pm mesons. The data were collected by the HERMES experiment at the HERA storage ring using 27.6 GeV electron and positron beams incident on a hydrogen or deuterium gas target. The results are presented as a function of the kinematic quantities x_B, Q^2, z, and P_h\perp. They represent a unique data set for identified hadrons that will significantly enhance our understanding of the fragmentation of quarks into final-state hadrons in deep-inelastic scattering.
64 data tables
pi+ multiplicities from HERMES, Target: H, Target: D, VM subtracted.
pi- multiplicities from HERMES, Target: H, Target: D, VM subtracted.
K+ multiplicities from HERMES, Target: H, Target: D, VM subtracted.
More…
#### Beam-Spin Asymmetries in the Azimuthal Distribution of Pion Electroproduction
The collaboration Airapetian, A. ; Akopov, Z. ; Amarian, M. ; et al.
Phys.Lett. B648 (2007) 164-170, 2007.
Inspire Record 735612
A measurement of the beam-spin asymmetry in the azimuthal distribution of pions produced in semi-inclusive deep-inelastic scattering off protons is presented. The measurement was performed using the {HERMES} spectrometer with a hydrogen gas target and the longitudinally polarized 27.6 GeV positron beam of HERA. The sinusoidal amplitude of the dependence of the asymmetry on the angle $\phi$ of the hadron production plane around the virtual photon direction relative to the lepton scattering plane was measured for $\pi^+,\pi^-$ and $\pi^0$ mesons. The dependence of this amplitude on the Bjorken scaling variable and on the pion fractional energy and transverse momentum is presented. The results are compared to theoretical model calculations.
6 data tables
Beam SSA as a function of Z, X, hadronic PT and Q**2.
Beam SSA as a function of Z, X, hadronic PT and Q**2.
Beam SSA as a function of Z, X, hadronic PT and Q**2.
More…
#### Precise determination of the spin structure function g(1) of the proton, deuteron and neutron
The collaboration Airapetian, A. ; Akopov, N. ; Akopov, Z. ; et al.
Phys.Rev. D75 (2007) 012007, 2007.
Inspire Record 726689
Precise measurements of the spin structure functions of the proton $g_1^p(x,Q^2)$ and deuteron $g_1^d(x,Q^2)$ are presented over the kinematic range $0.0041 \leq x \leq 0.9$ and $0.18$ GeV$^2$ $\leq Q^2 \leq 20$ GeV$^2$. The data were collected at the HERMES experiment at DESY, in deep-inelastic scattering of 27.6 GeV longitudinally polarized positrons off longitudinally polarized hydrogen and deuterium gas targets internal to the HERA storage ring. The neutron spin structure function $g_1^n$ is extracted by combining proton and deuteron data. The integrals of $g_1^{p,d}$ at $Q^2=5$ GeV$^2$ are evaluated over the measured $x$ range. Neglecting any possible contribution to the $g_1^d$ integral from the region $x \leq 0.021$, a value of $0.330 \pm 0.011\mathrm{(theo.)}\pm0.025\mathrm{(exp.)}\pm 0.028$(evol.) is obtained for the flavor-singlet axial charge $a_0$ in a leading-twist NNLO analysis.
23 data tables
Integrals of G1 for P, DEUT and N targets.. The second DSYS systematic error is due to the uncertainty in the parameterizations (R, F2, A2, Azz, omegaD).. The third DSYS systematic error is due to the uncertainty in evolving to a common Q**2.
Integrals of G1 for the Non-Singlet contributions.. The second DSYS systematic error is due to the uncertainty in the parameterizations (R, F2, A2, Azz, omegaD).. The third DSYS systematic error is due to the uncertainty in evolving to a common Q**2. Axis error includes +- 5.2/5.2 contribution.
Integrals of G1 over different X ranges for P target at various Q*2 values. The second DSYS systematic error is due to the uncertainty in the parameterizations (R, F2, A2, Azz, omegaD).. The third DSYS systematic error is due to the uncertainty in evolving to a common Q**2. Axis error includes +- 5.2/5.2 contribution.
More…
#### Double spin asymmetries in the cross-section of rho0 and phi production at intermediate-energies
The collaboration Airapetian, A. ; Akopov, N. ; Akopov, Z. ; et al.
Eur.Phys.J. C29 (2003) 171-179, 2003.
Inspire Record 613068
Double-spin asymmetries in the cross section of electroproduction of $\rho^0$ and $\phi$ mesons on the proton and deuteron are measured at the HERMES experiment. The photoabsorption asymmetry in exclusive $\rho^0$ electroproduction on the proton exhibits a positive tendency. This is consistent with theoretical predictions that the exchange of an object with unnatural parity contributes to exclusive $\rho^0$ electroproduction by transverse photons. The photoabsorption asymmetry on the deuteron is found to be consistent with zero. Double-spin asymmetries in $\rho^0$ and $\phi$ meson electroproduction by quasi-real photons were also found to be consistent with zero: the asymmetry in the case of the $\phi$ meson is compatible with a theoretical prediction which involves $s\bar{s}$ knockout from the nucleon.
7 data tables
The photoabsorption asymmetry A1 for exclusive RHO0 production.
The photoabsorption asymmetry A1 for exclusive PHI electroproduction.
The photoabsorption asymmetry A1 for electroproduction of RHO0 mesons by quasi-real photons.
More…
#### Double spin asymmetry in the cross-section for exclusive rho0 production in lepton - proton scattering
The collaboration Airapetian, A. ; Akopov, N. ; Akopov, Z. ; et al.
Phys.Lett. B513 (2001) 301-310, 2001.
Inspire Record 553236
7 data tables
The photoabsorption asymmetry A1 for exclusive RHO0 production.
The photoabsorption asymmetry A1 for exclusive RHO0 production as a function of Q**2.
The photoabsorption asymmetry A1 for exclusive RHO0 production as a function of W.
More…
#### The Q**2 dependence of the generalized Gerasimov-Drell-Hearn integral for the deuteron, proton and neutron
The collaboration Airapetian, A. ; Akopov, N. ; Akopov, Z. ; et al.
Eur.Phys.J. C26 (2003) 527-538, 2003.
Inspire Record 600098
The Gerasimov-Drell-Hearn (GDH) sum rule connects the anomalous contribution to the magnetic moment of the target nucleus with an energy-weighted integral of the difference of the helicity-dependent photoabsorption cross sections. The data collected by HERMES with a deuterium target are presented together with a re-analysis of previous measurements on the proton. This provides a measurement of the generalised GDH integral covering simultaneously the nucleon-resonance and the deep inelastic scattering regions. The contribution of the nucleon-resonance region is seen to decrease rapidly with increasing $Q^2$. The DIS contribution is sizeable over the full measured range, even down to the lowest measured $Q^2$. As expected, at higher $Q^2$ the data are found to be in agreement with previous measurements of the first moment of $g_1$. From data on the deuteron and proton, the GDH integral for the neutron has been derived and the proton--neutron difference evaluated. This difference is found to satisfy the fundamental Bjorken sum rule at $Q^2 = 5$ GeV$^2$.
6 data tables
The value of the GDH integral, as a function of Q**2 , for the deuteron in three W**2 regions, the total ( > 1 GeV**2), the nucleon resonance ( 1 to 4.2 GeV**2) and the DIS (4.2 to 45 GeV**2).
The value of the GDH integral, as a function of Q**2 , for the proton in three W**2 regions, the total ( > 1 GeV**2), the nucleon resonance ( 1 to 4.2 GeV**2) and the DIS (4.2 to 45 GeV**2).
The value of the GDH integral, as a function of Q**2 , for the neutron in three W**2 regions, the total ( > 1 GeV**2), the nucleon resonance ( 1 to 4.2 GeV**2) and the DIS (4.2 to 45 GeV**2).
More…
#### Multiplicity of charged and neutral pions in deep inelastic scattering of 27.5-GeV positrons on hydrogen
The collaboration Airapetian, A. ; Akopov, N. ; Akopov, Z. ; et al.
Eur.Phys.J. C21 (2001) 599-606, 2001.
Inspire Record 554660
Measurements of the individual multiplicities of pi+, pi- and pi0 produced in the deep-inelastic scattering of 27.5 GeV positrons on hydrogen are presented. The average charged pion multiplicity is the same as for neutral pions, up to approximately z= 0.7, where z is the fraction of the energy transferred in the scattering process carried by the pion. This result (below z= 0.7) is consistent with isospin invariance. The total energy fraction associated with charged and neutral pions is 0.51 +/- 0.01 (stat.) +/- 0.08 (syst.) and 0.26 +/- 0.01 (stat.) +/- 0.04 (syst.), respectively. For fixed z, the measured multiplicities depend on both the negative squared four momentum transfer Q^2 and the Bjorken variable x. The observed dependence on Q^2 agrees qualitatively with the expected behaviour based on NLO-QCD evolution, while the dependence on x is consistent with that of previous data after corrections have been made for the expected Q^2-dependence.
4 data tables
The measured PI0 multiplicity. Additional 9 PCT systematic error.
The measured multiplicity for charged pions, individually and the average. Additional 7 PCT systematic error.
The charged pion multiplicity as a function of x for four different z regions.
More…
#### The Q**2 dependence of the generalized Gerasimov-Drell-Hearn integral for the proton
The collaboration Airapetian, A. ; Akopov, N. ; Akushevich, I. ; et al.
Phys.Lett. B494 (2000) 1-8, 2000.
Inspire Record 531949
The dependence on Q^2 (the negative square of the 4-momentum of the exchanged virtual photon) of the generalised Gerasimov-Drell-Hearn integral for the proton has been measured in the range 1.2 GeV^2 < Q^2 < 12 GeV^2 by scattering longitudinally polarised positrons on a longitudinally polarised hydrogen gas target. The contributions of the nucleon-resonance and deep-inelastic regions to this integral have been evaluated separately. The latter has been found to dominate for Q^2 > 3 GeV^2, while both contributions are important at low Q^2. The total integral shows no significant deviation from a 1/Q^2 behaviour in the measured Q^2 range, and thus no sign of large effects due to either nucleon-resonance excitations or non-leading twist.
1 data table
The GDH integral as a function of Q2 in the resonance region (W**2 = 1 to 4.2 GeV**2), the measured region (W**2=4.2 to 45 GeV**2), and the total region (W**2= 1 to 45 GeV**2).
#### Exclusive leptoproduction of rho0 mesons from hydrogen at intermediate virtual photon energies
The collaboration Airapetian, A. ; Akopov, N. ; Akushevich, I. ; et al.
Eur.Phys.J. C17 (2000) 389-398, 2000.
Inspire Record 526550
Measurements of the cross section for exclusive virtual-photoproduction of rho^0 mesons from hydrogen are reported. The data were collected by the HERMES experiment using 27.5 GeV positrons incident on a hydrogen gas target in the HERA storage ring. The invariant mass W of the photon-nucleon system ranges from 4.0 to 6.0 GeV, while the negative squared four-momentum Q^2 of the virtual photon varies from 0.7 to 5.0 GeV^2. The present data together with most of the previous data at W > 4 GeV are well described by a model that infers the W-dependence of the cross section from the dependence on the Bjorken scaling variable x of the unpolarized structure function for deep-inelastic scattering. In addition, a model calculation based on Off-Forward Parton Distributions gives a fairly good account of the longitudinal component of the rho^0 production cross section for Q^2 > 2 GeV^2.
2 data tables
Cross sections are corrected for radiative effects (which typically amount s to 18 PCT).
Longitudinal cross sections. The listed uncertainties include both the total error on the measured RHO0 photoproduction cross sections and the error on theparametrization of R for W<7 GeV.
#### Measurement of the spin asymmetry in the photoproduction of pairs of high p(T) hadrons at HERMES
The collaboration Airapetian, A. ; Akopov, N. ; Amarian, M. ; et al.
Phys.Rev.Lett. 84 (2000) 2584-2588, 2000.
Inspire Record 503784
We present a measurement of the longitudinal spin asymmetry A_|| in photoproduction of pairs of hadrons with high transverse momentum p_T. Data were accumulated by the HERMES experiment using a 27.5 GeV polarized positron beam and a polarized hydrogen target internal to the HERA storage ring. For h+h- pairs with p_T^h_1 > 1.5 GeV/c and p_T^h_2 > 1.0 GeV/c, the measured asymmetry is A_|| = -0.28 +/- 0.12 (stat.) +/- 0.02 (syst.). This negative value is in contrast to the positive asymmetries typically measured in deep inelastic scattering from protons, and is interpreted to arise from a positive gluon polarization.
1 data table
Asymmetry measurement with a PT cut of 1.5 GeV on the hadron with the higher PT, and 1.0 GeV on the hadron with the lower PT.
#### Determination of the deep inelastic contribution to the generalized Gerasimov-Drell-Hearn integral for the proton and neutron
The collaboration Ackerstaff, K. ; Airapetian, A. ; Akopov, N. ; et al.
Phys.Lett. B444 (1998) 531-538, 1998.
Inspire Record 476388
The virtual photon absorption cross section differences [sigma_1/2-sigma_3/2] for the proton and neutron have been determined from measurements of polarised cross section asymmetries in deep inelastic scattering of 27.5 GeV longitudinally polarised positrons from polarised 1H and 3He internal gas targets. The data were collected in the region above the nucleon resonances in the kinematic range nu < 23.5 GeV and 0.8 GeV**2 < Q**2 < 12 GeV**2. For the proton the contribution to the generalised Gerasimov-Drell-Hearn integral was found to be substantial and must be included for an accurate determination of the full integral. Furthermore the data are consistent with a QCD next-to-leading order fit based on previous deep inelastic scattering data. Therefore higher twist effects do not appear significant.
13 data tables
Gerasimov-Drell-Hearn sum rule for proton as a function of Q2.
Gerasimov-Drell-Hearn sum rule for neutron as a function of Q2 (integral spans from Q2/2M to infinity instead of zero to infinity, see paper).
Cross section difference for the proton data. Statistical errors only.
More…
#### The Flavor asymmetry of the light quark sea from semiinclusive deep inelastic scattering
The collaboration Ackerstaff, K. ; Airapetian, A. ; Akopov, N. ; et al.
Phys.Rev.Lett. 81 (1998) 5519-5523, 1998.
Inspire Record 473345
The flavor asymmetry of the light quark sea of the nucleon is determined in the kinematic range 0.02<x<0.3 and 1 GeV^2<Q^2<10 GeV^2, for the first time from semi-inclusive deep-inelastic scattering. The quantity (dbar(x)-ubar(x))/(u(x)-d(x)) is derived from a relationship between the yields of positive and negative pions from unpolarized hydrogen and deuterium targets. The flavor asymmetry dbar-ubar is found to be non-zero and x dependent, showing an excess of dbar over ubar quarks in the proton.
1 data table
The ratio of parton distribution functions (PDF) is determined from the ratio of the differencies between charged pion yields for proton and neutron targets: (N_p(pi-)-N_n(pi-))/(N_p(pi+)-N_n(pi+)).
#### Measurement of the proton spin structure function g1(p) with a pure hydrogen target
The collaboration Airapetian, A. ; Akopov, N. ; Akushevich, I. ; et al.
Phys.Lett. B442 (1998) 484-492, 1998.
Inspire Record 473421
A measurement of the proton spin structure function g1p(x,Q^2) in deep-inelastic scattering is presented. The data were taken with the 27.6 GeV longitudinally polarised positron beam at HERA incident on a longitudinally polarised pure hydrogen gas target internal to the storage ring. The kinematic range is 0.021<x<0.85 and 0.8 GeV^2<Q^2<20 GeV^2. The integral Int_{0.021}^{0.85} g1p(x)dx evaluated at Q0^2 of 2.5 GeV^2 is 0.122+/-0.003(stat.)+/-0.010(syst.).
2 data tables
The second systematic errors listed for G1/F1 (G1) are the uncertainties concerning R (R and F2).
G1 evolved at Q2 = 2.5 GeV**2, assuming G1/F1 to be independent of Q2. The second systematic errors listed for are the uncertainties concerning R and F2.
#### Measurement of the neutron spin structure function g1(n) with a polarized He-3 internal target
The collaboration Ackerstaff, K. ; Airapetian, A. ; Akushevich, I. ; et al.
Phys.Lett. B404 (1997) 383-389, 1997.
Inspire Record 440904
Results are reported from the HERMES experiment at HERA on a measurement of the neutron spin structure function $g_1~n(x,Q~2)$ in deep inelastic scattering using 27.5 GeV longitudinally polarized positrons incident on a polarized $~3$He internal gas target. The data cover the kinematic range $0.023<x<0.6$ and $1 (GeV/c)~2 < Q~2 <15 (GeV/c)~2$. The integral $\int_{0.023}~{0.6} g_1~n(x) dx$ evaluated at a fixed $Q~2$ of $2.5 (GeV/c)~2$ is $-0.034\pm 0.013(stat.)\pm 0.005(syst.)$. Assuming Regge behavior at low $x$, the first moment $\Gamma_1~n=\int_0~1 g_1~n(x) dx$ is $-0.037\pm 0.013(stat.)\pm 0.005(syst.)\pm 0.006(extrapol.)$.
2 data tables
No description provided.
Data extrapolated to full x region. Second systematic error is the error on this extrapolation.
#### Hadronization in semi-inclusive deep-inelastic scattering on nuclei
The collaboration Airapetian, A. ; Akopov, N. ; Akopov, Z. ; et al.
Nucl.Phys. B780 (2007) 1-27, 2007.
Inspire Record 749249
A series of semi-inclusive deep-inelastic scattering measurements on deuterium, helium, neon, krypton, and xenon targets has been performed in order to study hadronization. The data were collected with the HERMES detector at the DESY laboratory using a 27.6 GeV positron or electron beam. Hadron multiplicities on nucleus A relative to those on the deuteron, R_A^h, are presented for various hadrons (\pi^+, \pi^-, \pi^0, K^+, K^-, p, and \bar{p}) as a function of the virtual-photon energy \nu, the fraction z of this energy transferred to the hadron, the photon virtuality Q^2, and the hadron transverse momentum squared p_t^2. The data reveal a systematic decrease of R_A^h with the mass number A for each hadron type h. Furthermore, R_A^h increases (decreases) with increasing values of \nu (z), increases slightly with increasing Q^2, and is almost independent of p_t^2, except at large values of p_t^2. For pions two-dimensional distributions also are presented. These indicate that the dependences of R_A^{\pi} on \nu and z can largely be described as a dependence on a single variable L_c, which is a combination of \nu and z. The dependence on L_c suggests in which kinematic conditions partonic and hadronic mechanisms may be dominant. The behaviour of R_A^{\pi} at large p_t^2 constitutes tentative evidence for a partonic energy-loss mechanism. The A-dependence of R_A^h is investigated as a function of \nu, z, and of L_c. It approximately follows an A^{\alpha} form with \alpha \approx 0.5 - 0.6.
228 data tables
PI+ multiplicty ratio (Helium/Deuterium) as a function of NU.
K+ multiplicty ratio (Helium/Deuterium) as a function of NU.
P multiplicty ratio (Helium/Deuterium) as a function of NU.
More… | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9725467562675476, "perplexity": 3844.2158666950754}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-18/segments/1555578616424.69/warc/CC-MAIN-20190423234808-20190424020808-00409.warc.gz"} |
http://meta.tex.stackexchange.com/questions/1272/why-doesnt-maths-render-as-maths | Why doesn't maths render as maths?
On some other SE sites, code in between dollar signs gets rendered as mathematics (using MathJaX, I believe). This doesn't seem to work here? Why not? And how do I get round it?
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See this question. You should know the answer to this, since you requested the behaviour :) – Lev Bishop Apr 18 '11 at 18:02
@Lev: My apologies, I meant to leave a comment on this but forgot. This is a "FAQ" question - I don't want to know the answer but I want to be able to point people to this question if they wonder about it. – Loop Space Apr 18 '11 at 18:11
This online LaTeX-to-png converter by Kyle Woodward can be helpful for short runs: 1.618034.com/latex.php – episanty Feb 18 '13 at 18:03
On this site, we want to see the actual code far more often than we want to see the rendered output, so MathJaX is not enabled for this site. If you want to show the result of some input, you need to create an image of the output and upload it. One of the simplest methods of getting an image from your code is to use the standalone package (see Compile a latex document into a png image that's as short as possible. for more details). To upload it, click on the "add image" button at the top of the text box (the box symbol next to the one with the 1s and 0s) and, if you have at least 10 reputation points, you will be able to upload the image and have it embedded in your question/answer.
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– naught101 Apr 3 '12 at 4:12
Also, MathJaX does not use TeX and thus renders differently and doesn't support all of (La)TeX and its packages. – Caramdir Jun 1 '12 at 3:34
People wanting to show ConTeXt output can use \startTEXpage...\stopTEXpage. The resulting PDF will be exactly as large as the content. You can upload the result directly --- tex.se takes care of the conversion to PNG. – Esteis Dec 8 '12 at 13:52
As someone who includes images in almost all of his questions and answers, can I say that this behaviour is annoying and IMHO basically unjustified? Make the escape code as complicated as you will but why don't you let people decide whether they want to show code, exactly rendered result or just the ballpark? In this question of mine I had to fiddle around with HTML markup and I really missed math.SX who use TeX where we don't tex.stackexchange.com/q/102149/13450 – Christian Mar 12 '13 at 17:18
@Christian I'm sorry you feel like that, but your last remark shows the source of the problem. Maths-SX does not use TeX. They use MathJaX. MathJaX is not TeX. I don't know a lot about MathJaX, but I don't think it supports siunitx and certainly doesn't support pgfmath. So MathJaX wouldn't have helped you and you would still have had to fiddle around with the HTML markup (not that I understand what fiddling you needed to do, sorry for being dense). What is so hard about uploading a screenshot? – Loop Space Mar 12 '13 at 19:15
@AndrewStacey Well, nothing is hard about uploading a screenshot. It's just time consuming and it's actually more time consuming then fiddling around with unicode chars and markup. When I said "TeX", I meant TeX markup/syntax, not one of the actual kernels. Now I'm going to add an answer because I need to upload a screenshot ;) – Christian Mar 12 '13 at 19:22
Just as a follow-up to the exchange with Andrew in the other answer, this is what my fiddling vs. what I would have like looks on tex.SE compared to math.SX:
No, it's not dramatic that this doesn't work and I could help myself with simple markup and by digging for that $\times$ sign. My point is, that it is a simple convenience that is already implemented, whose availability doesn't hurt anybody and creating an actual TeX file for this, compiling it, converting it to a PNG file and uploading it is so overkill for this use case. And I'm not even sure how well inline images work here.
And concerning the HTML/unicode solution compared to the TeX syntax: the latter might not be rendered by TeX but it still looks much better than what I came up with. Yes, I might have fetched a real minus sign from some unicode table, too, but the more work I have to invest to make such a simple thing look decent, the stronger – I feel – my point becomes really.
Just as a convenience, here's my question again that sparked these posts: Omit zeros before the decimal point and convert scientific notation in siunitx
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I'd say an image isn't really essential in your case, as a 'reference' version can be constructed happily in TeX code: $.80$ $-.12$, etc. Also it's about common cases: tex-sx is not a site about maths, it's about typesetting, and most of the time that's not maths. – Joseph Wright Mar 13 '13 at 8:07
In this case I feel that you want to use MathJaX to produce a particular rendering on the screen and the fact that MathJaX emulates TeX is irrelevant to this - it is simply convenient because you know it. Moreover, your question (as I read it) isn't about the look of the output but its format, in which case getting the right unicode characters isn't so important. Even simply writing 4.44 x 10^{-16} would do to show what output you want. So I'm afraid that I disagree with your conclusion and still think that MathJaX would cause more hassle than its worth. – Loop Space Mar 13 '13 at 10:00
@AndrewStacey You are right in your analysis that it's a mere convenience for the author and the reader of a post but so is TeX itself. It's not like an ugly book doesn't convey the same information as one with beautiful typesetting. And yes, it's just for math and it just makes sense because people on the site already know the syntax. I could accept this as a simple difference in opinion if I understood what exactly the hassle is that MathJaX would cause. You only said "people don't want this" and "there are alternatives", none of which is about hassle. – Christian Mar 13 '13 at 11:25
This particular question-and-answer was meant as a quick reference for people to link to. There was more discussion on meta and my arguments can be found at meta.tex.stackexchange.com/q/7/86 – Loop Space Mar 13 '13 at 12:14
@AndrewStacey Thanks for the pointer. None of the arguments there apply but I'll shut up anyway because it's pretty clear that you've made up your mind and I'm not going to change that. I can use the time I saved by not discussing this further to make like a million screenshots and figure out how to inline them. – Christian Mar 13 '13 at 20:01
When I first started hanging out here, having no mathjax support seemed stupid but as time passed by I'm now very very happy that it's not turned on. Especially the problems we had with a few of new users here it would have been a true nightmare. I understand why you feel this choice is dumb but I'm almost sure that your views will change especially when you start spotting the difference of MathJax and TeX from a distance and seeing how people force themselves for the proper commands to communicate in TeX lingo. – percusse Mar 13 '13 at 22:31
@percusse I'm sure I'll one day start to see the woman in the red dress but that still doesn't make such a post user-friendly to beginners, i.e. people who have been using TeX for less than 20 years or so :) – Christian Mar 14 '13 at 7:31
@Christian: I think you'll find that once you set up a system for easily taking screenshots, the problem basically disappears. For example, on Ubuntu I just press the Windows key and draw a rectangle around the desired area, and it automatically saves that as an image in a predefined folder. Click "Upload image", select the file, done. Since you're going to have a LaTeX editor and PDF viewer open when working on a question anyway, this really only requires minimal effort. – Jake Mar 16 '13 at 13:21
@Jake Yeah well, up until now, I much prefer a workflow that is independent on screen resolution and subpixel rendering by using the Gimp to render a PDF page into an image. Should I more often need a quick and ugly screenshot to cater to the needs of TeX.SE, I might need to set up such a mechanism as well. It would not make using math that I don't yet have in a TeX file much more easy to produce. – Christian Mar 16 '13 at 14:19
I could combine your suggestion with a system that makes producing math from TeX syntax more easy ... like math.SE, thereby utterly perverting the intentions of this artificial restriction which – I must confess – would fill me with great joy and deep satisfaction. – Christian Mar 16 '13 at 14:21 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8581365942955017, "perplexity": 984.7812689652477}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-35/segments/1409535917663.12/warc/CC-MAIN-20140901014517-00167-ip-10-180-136-8.ec2.internal.warc.gz"} |
https://www.shaalaa.com/question-paper-solution/cbse-science-10th-class-10-2018-2019_16881 | Science 31/3/3 2018-2019 CBSE Class 10 Question Paper Solution
Science [31/3/3]
Date & Time: 14th March 2019, 2:30 pm
Duration: 3h
(i) All Questions are Compulsary .
(ii) Internal Choice is given in Sections B ,C , D and E .
Section A
[1]1
Define 1 kilowatt hour.
Concept: Electric Power
Chapter: [0.042] Effects of Current
[1]2
Generally, we do not clean natural ponds or lakes but an aquarium needs periodic cleaning. Why?
Concept: Concept of Eco-System
Chapter: [0.052000000000000005] Our Environment
Section B
[2]3
List two causes of presbyopia. Draw labelled diagram of a lens used for the correction of this defect of vision.
Concept: Eye Defect and Its Correction: Myopia Or Near-sightedness
Chapter: [0.03] Natural Phenomena
[2]4
Show the formation of Na2O by the transfer of electrons.
Concept: Chemical Equation
Chapter: [0.015] Chemical Reactions
[2]5
[2]5.a
List in tabular form two differences between reflex action and walking.
Concept: Human Brain - Reflex Action
Chapter: [0.023] Control and Co-ordination in Animals and Plants
OR
[2]5.b
List in tabular form two differences between pepsin and trypsin.
Concept: The Digestive System in Human
Chapter: [0.024] Life Processes
Section C
[3]6
Name the process used to harness nuclear energy these days. Explain it briefly. List two advantages of using nuclear energy in place of fossil fuels.
Concept: Nuclear Energy
Chapter: [0.053] Sources of Energy
[3]7
Why are forests considered “biodiversity hot spots”? Suggest four approaches towards the conservation of forests.
Concept: Natural Resources - Forests and Wild Life - Stakeholders
Chapter: [0.051] Management of Natural Resources
[3]8
[3]8.a
What is atmospheric reflection? Explain with the help of a labelled diagram that the position of a star as seen by us is not its true position.
Concept: Refraction of Light
Chapter: [0.03] Natural Phenomena
OR
[3]8.b
When do we consider a student sitting in the class to be myopic? List two causes of this defect. Explain using a ray diagram how this defect of eye can be corrected.
Concept: Eye Defect and Its Correction: Myopia Or Near-sightedness
Chapter: [0.03] Natural Phenomena
[3]9
Write the chemical formula of washing soda. How can it be obtained from baking soda? List two industries in which washing soda is used for other purposes than washing clothes.
Concept: Properties of Acids
Chapter: [0.013999999999999999] Acids, Bases and Salts
[3]10
[3]10.a
Out of three metals P, Q and R, P is less reactive than Q and R is more reactive than P and Q both. Suggest an activity to arragne P, Q and R in order of their decreasing reactivity.
Concept: Acids
Chapter: [0.013999999999999999] Acids, Bases and Salts
OR
[3]10.b
Name the ore of mercury. With the help of balanced chemical equations, explain the process of extraction of mercury from its ore.
Concept: Difference Between Metals, Non-metals, and Metalloids
Chapter:
[3]11
(a) How is possible valency of an element determined from the electronic configuration of its atom ?
(b) Determine the valency of an element X whose atomic number is 15.
Concept: History of Periodic Table: Early Attempts at the Classification of Elements
Chapter: [0.013000000000000001] Periodic Classification of Elements
[3]12
What is haemoglobin? State the consequences of deficiency of haemoglobin in our bodies.
Concept: Concept of Transportation
Chapter: [0.024] Life Processes
[3]13
[3]13.a
Explain the following :
(a) Speciation
(b) Natural Selection
Concept: Evolution and Classification - Introduction
Chapter: [0.021] Heredity and Evolution
OR
[3]13.b
Mendel, in one of his experiments with pea plants, crossed a variety of pea plant having round seeds with one having wrinkled seeds. State Mendel’s observations giving reasons of F1 and F2 progeny of this cross. Also, list any two contrasting characters, other than round seeds of pea plants that Mendel used in his experiments.
Concept: Rules for the Inheritance of Traits - Mendel’S Contributions
Chapter: [0.021] Heredity and Evolution
[3]14
Explain the ways in which glucose is broken down in absence or shortage of oxygen.
Concept: Carbon: a Versatile Element
Chapter: [0.011000000000000001] Carbon Compounds
[3]15
List in tabular form three distinguishing features between cerebrum and cerebellum.
Concept: Human Brain - Reflex Action
Chapter: [0.023] Control and Co-ordination in Animals and Plants
Section D
[5]16
[5]16.a
What is hydrocarbon? Give its one example.
Concept: Carbon: a Versatile Element
Chapter: [0.011000000000000001] Carbon Compounds
[5]16.b
Give the structural difference between saturated and unsaturated hydrocarbons with two examples each.
Concept: Carbon: a Versatile Element
Chapter: [0.011000000000000001] Carbon Compounds
[5]16.c
Name of the following compounds :
Concept: Carbon: a Versatile Element
Chapter: [0.011000000000000001] Carbon Compounds
[5]17
[5]17.a
(a) What is double displacement reaction? Explain with an example.
(b) A small amount of quick lime is added to water in a beaker.
(i) Name and define the type of reaction that has taken place.
(ii) Write balanced chemical equation for the above reaction and the chemical name of the product formed.
(iii) List two main observations of this reaction.
Concept: Types of Chemical Change or Chemical Reaction - Direct Combination (or Synthesis) Reaction
Chapter: [0.015] Chemical Reactions
OR
[5]17.b
(a) Design an acitivity to demonstrate the decomposition reaction of lead nitrate.
(b) Draw labelled diagram of the experimental set-up. List two main observations.
(c) Write balanced chemical equation for the reaction stating the physical state of the reactant and the products.
Concept: Difference Between Metals, Non-metals, and Metalloids
Chapter:
[5]18
[5]18.a
List four characteristics of the image formed by a concave lens of focal length 20 cm when the object is placed at a distance of 40 cm from its optical centre.
Concept: Refraction of Light
Chapter: [0.03] Natural Phenomena
[5]18.b
The size of image of an object by a convex lens of focal length 20 cm is observed to be reduced to 1/3 rd of its size . Find the distance of the object from the optical centre of the lens .
Concept: Refraction of Light
Chapter: [0.03] Natural Phenomena
[5]19
[5]19.a
Three resistors of resistances R1 , R2 and R are connected (i) in series, and (ii) in parallel. Write expressions for the equivalent resistance of the combination in each case.
Concept: Effects of Current Introduction
Chapter: [0.042] Effects of Current
OR
[5]19.b
Two identical resistros of 12 Omega each are connected to a battery of 3V . Calculate the ratio of the power consumed by the resulting combinations with minimum resistance and maximum resistance.
Concept: Effects of Current Introduction
Chapter: [0.042] Effects of Current
[5]19.c
Write the relation between resistance and electrical resistivity of the material of a conductor in the shape of a cylinder of length 'l' and area of cross-section 'A' . Hence derive the S.I. unit of electrical resistivity.
Concept: Factors on Which the Resistance of a Conductor Depends
Chapter: [0.042] Effects of Current
[5]19.d
Resistance of a metal wire of length 5 m is 100 Ω . If the area of cross - section of the wire is 3 × 10^-7 "m"^2 , Calculate the resistivity of the metal .
Concept: Factors on Which the Resistance of a Conductor Depends
Chapter: [0.042] Effects of Current
[5]20
[5]20.a
Name and state the rule of determine the direction of force experienced by a current carrying straight conductor placed in a uniform magnetic field which is perpendicular to it.
Concept: Fleming’s Left Hand Rule
Chapter: [0.040999999999999995] Magnetic Effects of Current
[5]20.b
Draw a labelled diagram of an electric motor.
Concept: Electric Motor
Chapter: [0.040999999999999995] Magnetic Effects of Current
[5]21
[5]21.a
What is reproduction? List its two types.
Concept: Human Reproductive System
Chapter: [0.022000000000000002] Reproduction
[5]21.b
How are the modes of reproduction different in unicellular and multicellular organisms?
Concept: Human Reproductive System
Chapter: [0.022000000000000002] Reproduction
(OR)
[5]21.c
What are Sexually Transitted Diseases (STD)? List two viral and two bacterial STDs.
Concept: Reproductive Health
Chapter: [0.022000000000000002] Reproduction
[5]21.d
What is contraception ? List three reasons for adopting contraceptive methods.
Concept: Reproductive Health
Chapter: [0.022000000000000002] Reproduction
Section E
[2]22
(OR)
[2]22.a
In the expriment of preparing a temporary mount of a leaf peel to observe stomata, we use two liquids other than water. Name these two liquids and state when and why these liquids are used.
Concept: Mode of Nutrition in Plant - Heterotrophic Nutrition
Chapter: [0.024] Life Processes
[2]22.b
List four precautions in proper sequence which we observe while preparing a temporary mount of a leaf peel.
Concept: Mode of Nutrition in Plant - Heterotrophic Nutrition
Chapter: [0.024] Life Processes
[2]23
A student has set up "CO2 is released during respiration”. After about 1 hour he observes no change in the water level in the delivery tube. Write two possible resons for the failure of the experiment.
Concept: Respiration
Chapter: [0.024] Life Processes
[2]24
Consider the sacle of voltmeter shown in the diagram and answer the following questions :
(a) What is the least count of the voltmeter?
(b) What is the reading shown by the voltmeter ?
(c) If the voltmeter is connected across a resistor of 20 Omega how much current is flowing through the resistor?
Concept: Ohm’s Law
Chapter: [0.042] Effects of Current
[2]25
(OR)
[2]25.a
List in proper sequence the steps of the experiment for determining the approximate focal length of a given concave mirror by obtaining the image of a distant object.
Concept: Refraction of Light
Chapter: [0.03] Natural Phenomena
[2]25.b
A student has to trace the path of a ray of light passing through a rectangular glass slab for four different values of angle of incidence.
(a) Write two important precautions for this experiment.
(b) List two conclusions the student will draw based on his experiment.
Concept: Concave Mirror
Chapter: [0.03] Natural Phenomena
[2]26
List the conclusions you will draw while studying the following properties of ethanoic acid :
(a) Odour
(b) Solubility in water
(c) Effect on litmus paper
(d) Reaction with sodium hydrogen carbonate
Concept: Carbon: a Versatile Element
Chapter: [0.011000000000000001] Carbon Compounds
[2]27
[2]27.a
What is observed after about 1 hour of adding the strips of copper and aluminium separately to ferrous sulphate solution filled in two beakers ? Name the reaction if any change in colour is noticed. Also, write chemical equation for the reaction.
Concept: Difference Between Metals, Non-metals, and Metalloids
Chapter:
(OR)
[2]27.b
A student wants to study a decomposition reaction by taking ferrous sulphate crystals. Write two precautions he must observe while performing the experiment.
Concept: Types of Chemical Change or Chemical Reaction - Decomposition Reactions
Chapter: [0.015] Chemical Reactions
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• For finding solution of question papers no need to refer so multiple sources like textbook or guides. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6425133943557739, "perplexity": 4653.1429255353705}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-21/segments/1620243988775.25/warc/CC-MAIN-20210507060253-20210507090253-00401.warc.gz"} |
http://community.boredofstudies.org/showthread.php?s=&goto=lastpost&threadid=351289 | # Thread: International Baccalaureate Maths Marathon
1. ## International Baccalaureate Maths Marathon
$Decided to open up a thread on all questions related to the IB Diploma . The IB is a curriculum offered by most New South Wales schools and around the world as well. Thought we could get a bit more discussion up and going on a single thread.$
$Will start off with this question From SL Cambridge Page 150 Q 4$
$The sum of the first three terms of a geometric sequence is 23 \frac{3}{4} , and the sum of the first four terms is 40 \frac{5}{8}. Find the first term and the common ratio$
2. ## Re: International Baccalaureate Marathon 2016
Originally Posted by davidgoes4wce
$Decided to open up a thread on all questions related to the IB Diploma . The IB is a curriculum offered by most New South Wales schools and around the world as well. Thought we could get a bit more discussion up and going on a single thread.$
$Will start off with this question From SL Cambridge Page 150 Q 4$
$The sum of the first three terms of a geometric sequence is 23 \frac{3}{4} , and the sum of the first four terms is 40 \frac{5}{8}. Find the first term and the common ratio$
Are you sure the IB is offered by most New South Wales schools? I thought it was relatively uncommon in NSW schools.
3. ## Re: International Baccalaureate Marathon 2016
Here was my attempt:
$S_3=\frac{a(r^3-1)}{r-1}$
$\frac{95}{4}=\frac{a(r^3-1)}{r-1} \textcircled{1}$
$S_4=\frac{a(r^4-1)}{r-1}$
$\frac{325}{8}=\frac{a(r^4-1)}{r-1} \textcircled{2}$
4. ## Re: International Baccalaureate Marathon 2016
Originally Posted by InteGrand
Are you sure the IB is offered by most New South Wales schools? I thought it was relatively uncommon in NSW schools.
I should have taken the word 'most' out of it. But I do know that St.Andrews Cathedral and Newington are 2 schools that offer it.
5. ## Re: International Baccalaureate Marathon 2016
Originally Posted by InteGrand
Are you sure the IB is offered by most New South Wales schools? I thought it was relatively uncommon in NSW schools.
Most rich private schools lel
6. ## Re: International Baccalaureate Marathon 2016
$T_4=S_4-S_3$
$T_4=\frac{325}{8}-\frac{95}{4} =\frac{135}{8}$
$Equating T_4=ar^{4-1}$
$\frac{135}{8}=ar^3$
7. ## Re: International Baccalaureate Marathon 2016
Originally Posted by Nailgun
Most rich private schools lel
The thing I learnt also, especially in NSW= rich doesn't necessarily mean better.
8. ## Re: International Baccalaureate Marathon 2016
Originally Posted by davidgoes4wce
The thing I learnt also, especially in NSW= rich doesn't necessarily mean better.
words to live by
9. ## Re: International Baccalaureate Marathon 2016
I also get the feeling this question has substitution and cancelling involved, would be great if somebody can get the derived working out as I spent around 15-20 minutes on the question.
10. ## Re: International Baccalaureate Marathon 2016
Originally Posted by InteGrand
Are you sure the IB is offered by most New South Wales schools? I thought it was relatively uncommon in NSW schools.
some
11. ## Re: International Baccalaureate Marathon 2016
Originally Posted by davidgoes4wce
I should have taken the word 'most' out of it. But I do know that St.Andrews Cathedral and Newington are 2 schools that offer it.
Trinity Grammar, MLC, Ravenswood, Kambala, Queenswood, Monte Sant Angelo, S.C.E.G.G.S. Redlands, . . . .
12. ## Re: International Baccalaureate Marathon 2016
Originally Posted by davidgoes4wce
$Decided to open up a thread on all questions related to the IB Diploma . The IB is a curriculum offered by most New South Wales schools and around the world as well. Thought we could get a bit more discussion up and going on a single thread.$
$Will start off with this question From SL Cambridge Page 150 Q 4$
$The sum of the first three terms of a geometric sequence is 23 \frac{3}{4} , and the sum of the first four terms is 40 \frac{5}{8}. Find the first term and the common ratio$
ar³ = 135/8 from the difference of the series.
a(1+r+r²+r³) = 205/8
1+r⁻¹+r⁻²+r⁻³ = 41/27
which is the quotient of the above two expressions.
From here, it can be solved for r⁻¹ and then a can be found.
13. ## Re: International Baccalaureate Marathon 2016
ar³ = 135/8 from the difference of the series.
a(1+r+r²+r³) = 205/8
1+r⁻¹+r⁻²+r⁻³ = 41/27
which is the quotient of the above two expressions.
From here, it can be solved for r⁻¹ and then a can be found.
You did everything right except for that last line
1+r^-1+r^-2+r^-3=65/27
It's been a long day, and you had to do the division, which correctly pointed out. This is the kind of question they put to a Year 11, I think after today I will just stick to the Haeese textbooks (which are considerably easier).
14. ## Re: International Baccalaureate Marathon 2016
$S_4= \frac{325}{8}$
$a+ar^2+ar^3+ar^4=\frac{325}{8}$
$Dividing both LHS and RHS by ar^3=\frac{135}{8}$
$\frac{a+ar+ar^2+ar^3}{ar^3}=\frac{325}{8} \div \frac{135}{8}$
$r^{-3}+r^{-2}+r^{-1}+1=\frac{325}{135}$
$r^{-3}+r^{-2}+r^{-1}+1=\frac{65}{27}$
From there you have to use Trial and Error to solve for r or a graphics calculating facility (where they have Equation Solver )
15. ## Re: International Baccalaureate Marathon 2016
This is a Band 6 Question in IB maths..........................In IB they have 7 bands
16. ## Re: International Baccalaureate Marathon 2016
Originally Posted by davidgoes4wce
This is a Band 6 Question in IB maths..........................In IB they have 7 bands
what fun.
what fun.
Just Saying
18. ## Re: International Baccalaureate Marathon 2016
What do you reckon is harder, NSW maths or IB maths?
19. ## Re: International Baccalaureate Marathon 2016
Originally Posted by Rathin
What do you reckon is harder, NSW maths or IB maths?
Does this really have to be asked
20. ## Re: International Baccalaureate Marathon 2016
Originally Posted by leehuan
Does this really have to be asked
Do you mean the answer is obvious, or the question isn't of interest?
21. ## Re: International Baccalaureate Marathon 2016
im just curious lol
22. ## Re: International Baccalaureate Marathon 2016
My legal teacher full roasts us on how dumb we are and how much 'better' the IB kids are and whatnot...
23. ## Re: International Baccalaureate Marathon 2016
Originally Posted by InteGrand
Do you mean the answer is obvious, or the question isn't of interest?
The former haha
24. ## Re: International Baccalaureate Marathon 2016
The IB is a more rigorous and demanding programme than the NSW HSC.
You can't just pick a group of any subjects that you fancy from a menu of 100 items. If you choose the IB Maths (HL), and opted for the "Calculus" [previously called the 'Series & Differential Equations'], as most schools here do, you have to do: Sequences & Series [and their convergence/divergence, Squeeze Thm, L'Hopital's, etc ], Improper Integrals, Power Series, Maclaurin & Taylor series, Error Term, Radius and Interval of Covergence etc, Differential Equations etc.
The core course includes: vectors, dot and cross product, and Equations (vector, parametric, Cartesian) of a line, a plane , their intersection, solution sets to a set of linear equations in x, y, z.
25. ## Re: International Baccalaureate Marathon 2016
I think I'll be honest, if you read the Haeese Maths textbooks (which are published in Adelaide), you would say the NSW curriculum is harder.
Let's not kid ourselves, doing an international recognised curriculum you would generally expect the standards to be alot higher.
IB Maths November 2014
Maths Studies Candidates 2455
Maths SL Candidates 4093
Maths HL candidates 1333
IB Maths May 2014
Maths Studies 29,235
Maths SL 38,926
Maths HL 11,484
From what I gather there are two testing seasons one in May and one in November. From what I gather , is that the students in Australia prepare for the November exam. Whereas the Northern Hemisphere counterparts have to prepare for the May.
Australia has the largest intake participation in November according to the IB website with 1916/11125=17.22% candidates participating.
United States of America has the largest intake participation in May according to the IB Website with 73,028/137,330=53.17% candidates participating.
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http://mathhelpforum.com/advanced-algebra/73612-span-print.html | # Span
• February 14th 2009, 01:10 PM
krepka
Span
Let W be the set of all (X1, X2, X3, X4, X5) in R5 which satisfy
2X1-X2+4/3X3-X4=0
X1+2/3X3-X5=0
9X1-3X2+6X3-3X4-3X5=0
Find a finite set of vectors which spans W
Does this mean I have to find the vectors such that
c1V1+c2V2+c3V3+c4V4+c5V5=(X1, X2, X3, X4, X5) for some uknown V? And if so, what's the best way to go about it, by row-reducing the matrix above?
Thanks.
• February 14th 2009, 02:17 PM
HallsofIvy
Quote:
Originally Posted by krepka
Let W be the set of all (X1, X2, X3, X4, X5) in R5 which satisfy
2X1-X2+4/3X3-X4=0
X1+2/3X3-X5=0
9X1-3X2+6X3-3X4-3X5=0
Find a finite set of vectors which spans W
Does this mean I have to find the vectors such that
c1V1+c2V2+c3V3+c4V4+c5V5=(X1, X2, X3, X4, X5) for some uknown V? And if so, what's the best way to go about it, by row-reducing the matrix above?
Thanks.
Since there is no "V" in what you give, I have to answer no! But if your question is "Do I have to find vectors (not necessarily 5) so that every (X1, X2, X3, X4, X5) can be written as a linear combination of them (c1V1+ c2V2+ ...)" then the answer is yes.
In fact, because you have 5 variables with 3 equations you will need at least 5- 3= 2 such vectors and the equations are dependent, up to 4. And I see now that math2009 has shown that they are NOT independent. 3 vectors are required
yes, you could row-reduce a matrix but I would recommend this: use the three equations to solve for three of the "X"s in terms of the other two, say solve for X3, X4, and X5 in terms of X1 and X2. Then setting X1= 1, X2= 0 will give you one vector in that set and setting X1= 0, X2= 1 will give you another. The choices of "1, 0" then "0, 1" ensure those vectors are independent so they will span the set (in fact they form a basis for the subspace).
• February 14th 2009, 03:32 PM
math2009
$\vec{x} \in W\ ,W\ is\ subspace\ of\ R^5\ ,A=\begin{bmatrix} 2&-1&\frac{4}{3}&-1&0 \\1&0&\frac{2}{3}&0&-1 \\9&-3&6&-3&-3 \end{bmatrix}\ , A\vec{x}=\vec{0},\ W=ker(A)$
We convert the problem "find W" to "find kernel of matrix A".
$rref(A)=\begin{bmatrix} 1&0&\frac{2}{3}&0&-1 \\0&1&0&1&-2 \\ 0&0&0&0&0 \end{bmatrix}\ , rank(A)=2,dim(ker(A))=5-rank(A)=3$, we need at least 3 linear independent vectors to span $W$
$W=\begin{bmatrix} -\frac{2}{3}m+t\\ -n+2t \\m \\n \\t \end{bmatrix}=m\begin{bmatrix} -\frac{2}{3}\\ 0 \\1 \\0 \\0 \end{bmatrix}+n\begin{bmatrix} 0\\ -1 \\0 \\1 \\0 \end{bmatrix}+t\begin{bmatrix} 1\\ 2 \\0 \\0 \\1 \end{bmatrix}=span(\begin{bmatrix} -\frac{2}{3}\\ 0 \\1 \\0 \\0 \end{bmatrix},\begin{bmatrix} 0\\ -1 \\0 \\1 \\0 \end{bmatrix},\begin{bmatrix} 1\\ 2 \\0 \\0 \\1 \end{bmatrix})$
• February 14th 2009, 05:18 PM
krepka
Thanks for the replies. Following your method, HallsofIvy, I got
(1,0,0,2,1);(0,1,0,-1,0); and (0,0,1,4/3,2/3). These are different from math2009's answers. Given that I don't yet know what "the kernel of A" is, I'm going to trust that the vectors I found form the basis for the subspace.
Thanks again.
• February 14th 2009, 07:47 PM
math2009
$\begin{bmatrix} 1\\ 0 \\0 \\2 \\1 \end{bmatrix}=2\begin{bmatrix} 0\\ -1 \\0 \\1 \\0 \end{bmatrix}+\begin{bmatrix} 1\\ 2 \\0 \\0 \\1 \end{bmatrix} \ , \
\begin{bmatrix} 0\\ 1 \\0 \\-1 \\0 \end{bmatrix}=-\begin{bmatrix} 0\\ -1 \\0 \\1 \\0 \end{bmatrix}$
, $\begin{bmatrix} 0\\ 0 \\1 \\ \frac{4}{3} \\ \frac{2}{3} \end{bmatrix}=\begin{bmatrix} -\frac{2}{3}\\ 0 \\1 \\0 \\0 \end{bmatrix}+\frac{4}{3} \begin{bmatrix} 0\\ -1 \\0 \\1 \\0 \end{bmatrix}+\frac{2}{3} \begin{bmatrix} 1\\ 2 \\0 \\0 \\1 \end{bmatrix}
$
It means we have the same solution. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 6, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.805233359336853, "perplexity": 524.9908134032037}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-41/segments/1410657123996.28/warc/CC-MAIN-20140914011203-00345-ip-10-196-40-205.us-west-1.compute.internal.warc.gz"} |
http://math.stackexchange.com/users/23431/pbs?tab=activity&sort=all&page=10 | pbs
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App developer, Research Associate, and Lecturer of and dabbler in Mathematics.
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Mar26 accepted Why does this product diverge? Mar26 comment Why does this product diverge? Ok, thanks all I think I've cleared this up now. Basically it all depends on what we mean by an infinite product. Using the standard "sequence of partial products" then we have divergence, but if we explicitly state @Sabyasachi's intention, $$\lim_{n\to\infty}\prod_{k=1}^{2n}a_n,$$ then we have convergence. Delicate! Mar26 comment Why does this product diverge? This is where I misunderstand. The upper index in the product is always $2n$, so by definition the product is never defined with an upper index of $2n+1$. Maybe this is one of those "murky" $\infty$ areas since $\infty$ is not a natural number? ... Mar26 asked Why does this product diverge? Mar26 comment Necessary/sufficient conditions for an infinite product to be exactly equal to $1$ When $p=1$, taking logarithms gives $\log p=0$ not $\log p=\infty$. Is that a typo? Mar26 revised Necessary/sufficient conditions for an infinite product to be exactly equal to $1$ added 82 characters in body Mar25 comment Necessary/sufficient conditions for an infinite product to be exactly equal to $1$ Yes, I thought so. Thanks. Is this still the case if the $a_n$ are monotone decreasing or increasing? Mar25 asked Necessary/sufficient conditions for an infinite product to be exactly equal to $1$ Mar19 revised Find $(a+ib)^{492}$ given that $(a+ib)^{493}=1$ added 5 characters in body Mar13 comment Logarithmic quotient Given the distinction made, what base logarithm is $\log$ here ? Also - you're missing a bracket second line up from the bottom. Mar13 comment Describing the sequence A224239. Analytic Combinatorics may be of help. Try constructing a class of combinatorial objects you require and then apply a transfer function to obtain a generating function which you can solve explicitly or asymptotically. Mar9 comment Help finding value of x in logarithms? Presumably you $\log$ is base $10$? Mar9 comment Help finding value of x in logarithms? Raise both sides to the power $1/8.4$. Mar8 comment Can every definite integral be computed symbolically? But what about when $b=\infty$... Mar4 revised if $f(x) = \int_{t=1}^{t=x^2} t\sin^2(t)\operatorname d\!t$ then $\frac{\operatorname d\!f(x)}{\operatorname d\!x}=?$ added 2 characters in body Mar4 suggested suggested edit on Is the intersection empty? Feb28 accepted Solution of “quadratic equation” involving functional coefficients. Feb27 revised Solution of “quadratic equation” involving functional coefficients. added 12 characters in body Feb27 revised Solution of “quadratic equation” involving functional coefficients. edited body Feb27 asked Solution of “quadratic equation” involving functional coefficients. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9015511870384216, "perplexity": 1054.6367087036288}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-41/segments/1410657137145.1/warc/CC-MAIN-20140914011217-00086-ip-10-234-18-248.ec2.internal.warc.gz"} |
https://xplaind.com/408368/cost-functions | # Cost Functions
A cost function is a mathematical relationship between cost and output. It tells how costs change in response to changes in output.
Even though relationship between a firm’s costs and output can be studies using cost tables (which show total cost, total variable cost and marginal cost for each unit) or graphs which plot different cost curves, a cost function is the most compact and direct method of encapsulating information about a firm’s costs.
Cost functions typically have cost as a dependent variable and output i.e. quantity as an independent variable. Such cost functions do not account for any changes in cost of inputs because they assume fixed input prices.
## Types of Cost Functions
Typical cost functions are either linear, quadratic and cubic.
A linear cost function is such that exponent of quantity is 1. It is appropriate only for cost structures in which marginal cost is constant.
A quadratic cost function, on the other hand, has 2 as exponent of output. It represents a cost structure where average variable cost is U-shaped.
A cubic cost function allows for a U-shaped marginal cost curve. The cost function in the example below is a cubic cost function.
Total cost function is the most fundamental output-cost relationship because functions for other costs such as variable cost, average variable cost and marginal cost, etc. can be derived from the total cost function.
## Example
Imagine you work at a firm whose total cost (TC) function is as follows:
$$\text{TC}\ =\ \text{0.1Q}^\text{3}-\ \text{2Q}^\text{2}+\text{60Q}+\text{200}\$$
Average total cost function can be derived by dividing the total cost function by Q:
$$\text{ATC}\ =\ \frac{\text{TC}}{\text{Q}}=\text{0.1Q}^\text{2}-\ \text{2Q}+\text{60}+\frac{\text{200}}{\text{Q}}\$$
The constant value in a total cost function represent the total fixed cost. Function for total variable cost can be arrived at by subtracting the constant value from the total cost function:
$$\text{VC}=\text{TC}\ -\ \text{FC}\$$
$$\text{VC}=\ \text{0.1Q}^\text{3}-\ \text{2Q}^\text{2}+\text{60Q}$$
Average variable cost function equals total variable cost divided by Q:
$$\text{AVC}=\frac{\text{VC}}{\text{Q}}=\ \text{0.1Q}^\text{2}-\ \text{2Q}+\text{60}$$
Marginal cost equals the slope of the total cost curve which in turn equals the first derivative of the total cost function.
$${\text{MC}} _ \text{Q}=\frac{\text{dTC}}{\text{dQ}}\ =\ \text{0.3Q}^\text{2}-\ \text{4Q}+\text{60}\$$
Cost functions can be used to create cost tables and cost curves. By plugging different quantity levels in the cost functions determined above, we can create a cost table which can be used to plot the cost curves.
The total cost and total variable cost curves represented by functions discussed above give us the following graph:
Since the total cost function is a cubic-function, the average variable cost curve and the marginal cost curve are U-shaped as shown below. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.16316255927085876, "perplexity": 736.957759007193}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-26/segments/1560628001138.93/warc/CC-MAIN-20190627115818-20190627141818-00471.warc.gz"} |
http://math.stackexchange.com/questions/202760/prove-the-trigonometric-identity?answertab=oldest | # Prove the trigonometric identity
$$\cos^2\alpha-\cos^4\alpha+\sin^4\alpha=\frac{1}{2}-\frac{1}{2}\cos2\alpha$$
-
Welcome to math.SE: since you are new, I wanted to let you know a few things about the site. In order to get the best possible answers, it is helpful if you say in what context you encountered the problem, and what your thoughts on it are; this will prevent people from telling you things you already know, and help them give their answers at the right level. – Julian Kuelshammer Oct 14 '12 at 13:25
Implement the formula:
1) $1-\cos^2\alpha=\sin^2\alpha$
2) $\cos2\alpha=\cos^2\alpha-\sin\alpha$
3) $1=\sin^2\alpha+\cos^2\alpha$
Now turn the proof given identity.
$\cos^2\alpha-\cos^4\alpha+\sin^4\alpha=\frac{1}{2}-\frac{1}{2}\cos2\alpha$
$\cos^2\alpha(1-\cos^2\alpha)+\sin^4\alpha=\frac{1}{2}(1-\cos2\alpha)$
$\cos^2\alpha\sin^2\alpha+\sin^4\alpha=\frac{1}{2}(\sin^2\alpha+\cos^2\alpha-\cos^2\alpha+\sin^2\alpha)$
$\sin^2\alpha(\cos^2\alpha+\sin^2\alpha)=\frac{1}{2}\cdot 2\sin^2\alpha$
$\sin^2\alpha=\sin^2\alpha$
-
This is badly formatted: One says in effect that if a certain equality holds, then $\sin^2\alpha=\sin^2\alpha$, and concludes that that equality holds. One should be "$=$" between, for example, $\cos^2\alpha-\cos^4\alpha+\sin^4\alpha$ and the thing on the line after it, $\cos^2\alpha(1-\cos^2\alpha+\sin^4\alpha$, and so on. – Michael Hardy Sep 26 '12 at 13:09
Use the identities, $\sin^2\alpha+\cos^2\alpha=1$ and $\cos2\alpha=1-2\sin^2\alpha$
Since, $\cos^2\alpha-\cos^4\alpha=\cos^2\alpha(1-\cos^2\alpha)=\cos^2\alpha\cdot\sin^2\alpha$
So, $$\cos^2\alpha-\cos^4\alpha+\sin^4\alpha=\cos^2\alpha\cdot\sin^2\alpha+\sin^4\alpha$$ $$=\sin^2\alpha(\cos^2\alpha+\sin^2\alpha)$$ $$=\sin^2\alpha=\frac{1-\cos2\alpha}{2}$$
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$$\cos^2\alpha-\cos^4\alpha+\sin^4\alpha=\cos^2\alpha+(\sin^4\alpha-\cos^4\alpha)=$$ $$=\cos^2\alpha+(\sin^2\alpha+\cos^2\alpha)(\sin^2\alpha-\cos^2\alpha)=\cos^2\alpha+\sin^2\alpha-\cos^2\alpha=$$ $$=\sin^2\alpha=1/2-1/2\cos2\alpha$$ Over!
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Yes ,youare right! – Riemann Sep 26 '12 at 11:46
This is a better answer than the "accepted" one. – Michael Hardy Sep 26 '12 at 13:09 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8776759505271912, "perplexity": 729.63344592355}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-22/segments/1432207929656.4/warc/CC-MAIN-20150521113209-00020-ip-10-180-206-219.ec2.internal.warc.gz"} |
http://lists.gnu.org/archive/html/emacs-devel/2004-06/msg00703.html | emacs-devel
[Top][All Lists]
## Re: query-replace-interactive not documented
From: Richard Stallman Subject: Re: query-replace-interactive not documented Date: Wed, 16 Jun 2004 12:57:42 -0400
If there are always to be parens around, then there would be no need for
!. One could just write
\\footnote{\\label{fn:$$+ replace-count$$}
I prefer the \! syntax, since it does not mess up the parens.
! is used in many programs to mean "execute" (usually
with a shell command, but we can ignore that).
Using \' does not seem to make sense, since this is not quoting. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9348267316818237, "perplexity": 4272.283548899581}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-41/segments/1410657134511.2/warc/CC-MAIN-20140914011214-00299-ip-10-234-18-248.ec2.internal.warc.gz"} |
https://math.stackexchange.com/questions/2356410/trouble-with-pumping-lemma | # Trouble with Pumping Lemma
I need to know if this language $$L = \{ \ (a^2b^2c^2)^n \mid n > 0\ \}$$ is regular or not.
Since it is trivial to design an FSA with a loop that accepts that language, it is regular. For example here is my FSA that accept language L using draw.io
I'm trying to prove that it is regular by using the pumping lemma.
My try:
Suppose $L$ is regular.
I choose $3$ as pumping length $P$
$$|S| \geqq P$$
Using my string $S = aabbcc\ aabbcc\ aabbcc$
The first block is $x$, the second is $y$ and the third is $z.$
I pump $y$ in $yy$ and I got
$aabbcc\ aabbcc\ aabbcc\ aabbcc$
And this satisfies the first condition because $xy^iz \in L$ The second is satisfied also because $|y|>0.$
But I need some help for the third condition that is
$$|xy|\leq P$$
$|xy|$ is the length of the first string or the second, where I applied the pumping lemma? How can I calculate this?
Since $P$ is $3$ (because it is chosen by me) I can't verify this language.
Any help appreciated. Thank you.
As a preliminary observation, your automaton assumes that the alphabet is $\{aa,bb,cc\}$. If the alphabet is $\{a,b,c\}$ instead, you need seven states.
With the preliminary out of the way, the pumping lemma for regular languages is typically used to prove that a language is not regular (as noted by @ChistianIvicevic). All you can do if the language is regular is to verify that it satisfies the conditions spelled out in the lemma. Let's see why you are having difficulty doing that.
The lemma says that for a regular language $L$ there exists a constant $P$, which is known as the pumping length, such that some condition that depends on $P$ is true.
This means that in verifying that the pumping lemma holds for $L$, you don't get to pick an arbitrary $P$: you have to find a value that works. If you have an automaton for $L$ with $n$ states, it's easy: $P$ should be at least $n$. (Why? Because the pumping lemma rests on a simple application of the pigeonholing principle: if there are more letters in an accepted word than states in the automaton, at least one state will be visited twice when the automaton reads the word.)
Assuming your automaton has four states (that is, $aa$ is a single letter) $P=3$ is not a good choice. With $P=4$ you can still choose the same $S$ as you did, though $S' = aabbcc~aabbcc$ is enough for demonstration purposes.
Now you can split $S'$ into $x=\epsilon$, $y=aabbcc$, and $z=aabbcc$ and verify that all conditions are met.
Alternatively, you can split $S$ into $x=\epsilon$, $y=aabbcc$, and $z=aabbcc~aabbcc$ and verify that all conditions are met.
The lemma says that there exists $P$ (you have to pick a good one) such that for any $S$ in $L$ of length at least $P$ (here you get to choose freely among the words in the language that are long enough) there is a way to write $S$ as $xyz$ (once again, you have to split correctly, not arbitrarily) such that all conditions are met.
In your example, you chose $P$ and the way to split $S$ arbitrarily. Therefore the fact that not all the conditions on $x,y,z$ were satisfied does not contradict the pumping lemma.
If you have an automaton for $L$, as you do, not only picking $P$, but also splitting a word in $L$ is easy: just run it through the automaton and find the first state visited more than once. Then $x$ is the prefix of the word that takes the automaton to that state the first time, $y$ is the segment of the word that causes the automaton to loop back to that state, and $z$ is the rest of the word.
Your language is $(aabbcc)^+$ (= $aabbcc(aabbcc)^*$ if you prefer). Since it is given by a regular expression, it is regular. No need of computing an automaton for that.
The pumping lemma states that all regular languages satisfy certain conditions but the converse it not true. A language that satisfies mentioned conditions may still be non-regular. Thus the pumping lemma is a necessary but not sufficient condition.
To prove a language is regular you can either:
1. Construct an NFA that accepts the language.
2. Construct a regular expression that describes all words from the language.
3. Construct a regular grammar that matches the language.
You just have to show correctness in each variant. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.85892653465271, "perplexity": 149.39274386177414}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-22/segments/1558232256215.47/warc/CC-MAIN-20190521022141-20190521044141-00155.warc.gz"} |
https://www.gamedev.net/forums/topic/696756-command-frames-and-tick-synchronization/?page=1 | Command Frames and Tick Synchronization
Recommended Posts
Posted (edited)
Hello,
This is actually my first post after being a lurker for quite some time here.
For the last couple of days I try to get my head around the concept of Overwatch's multiplayer architecture after watching the GDC 2017 talks by Timothy Ford ("Overwatch Gameplay Architecture and Netcode") and Dan Reed ("Networking Scripted Weapons and Abilities in Overwatch"). ( I hope someone here has Vault Access :D)
As usual with such complex systems Overwatch seems to combine different approaches to hide latency. Among others, the ones I am mostly interested in are, Command Frames and State Synchronization. I think I understood both concepts but I have problems adding them up.
1) Ford talks about the client being in the future by ~ half the RTT plus one command frame. This ensures that all commands sent from the client to the server tend to arrive when the server is actually at the tick referenced in the command. If that's correct my assumption would be the following:
• Server is at tick 1000.
• RTT is ~ 10 ticks -> around 10*16.6 ms.
• Client simulates tick 1005 and sends command associated with tick 1005.
<5 ticks later>
• Server is at tick 1005 and received a client command. (maybe its already queued in a buffer).
• Server applies command and sends state for tick 1006 (State_N + Input_N = State_N=1).
• RTT might still be 10 ticks.
• Client simulates tick 1010.
<5 ticks later>
• Server is at tick 1010...
• Client received State for tick 1005 and checks internal buffers for prediction.
Does that really apply? Does the client really simulate half-rtt in the future?
2) How do I handle ticks at the start of the game? My network layer requires a timestamp to work and I'd use ticks in the main game loop. Do I have something like a grace period until the client can calculate the required ticks to move to the future (by calling simulation.Tick(1/60f) for the number of ticks to be in the future)?
3) If I run the simulation at 60Hz and the network layer at say 20Hz. Do I have 60 Inputs that I send from Client to Server or 20?
I know, this is somewhat similar to other questions in this forum, but I feel like this particular talk has never been discussed?
Cheers,
poettlr
Edited by poettlr
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Quote
Does that really apply? Does the client really simulate half-rtt in the future?
Yes, this frequently happens, especially in action games.
Quote
How do I handle ticks at the start of the game?
Typically, the first connection message will tell you what tick the server was at, and you can snap your tick delta to that value plus some guess to get within the ballpark. A few more packets will then get the tick offset "dialed in" using whatever normal mechanism you use to synchronize tick/time offsets. If all of the servers are on a synchronized clock, this happens during login, so your tick is already synchronized when you start listing available games to join. If you use user-hosted servers, then you need to synchronize when you first get introduced to the user-hosted server, which can typically happen while you're loading the game level and doing other pre-game / lobby activities.
Quote
Do I have 60 Inputs that I send from Client to Server or 20?
Typically 60.
Note that, with modern systems running at 120 Hz or 144 Hz, and Virtual Reality benefiting from up to 120 Hz update rate, you may want to re-think the "60 Hz is the base rate" common wisdom, and run your loop faster. USB has a latency of a single millisecond if you have really good mice/keyboards/gamepads.
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I actually use dedicated servers but they are managed via a REST API.
So for now my last big problem will be client/server time synchronization, after searching through the forum I have some plans on how I want to approach that. I plan to include the server time and server tick (at the time of sending the packet) in all state sync packets or send the server time/tick at a given interval (be it at 5Hz or less). Since my network layer already provides me with RTT I think I have all variables in place to do that.
Probably something including a stopwatch.ElapsedTimeMilliseconds since the last received packet on the client. Or just using the RTT since the game should run on a fixed loop anyway.
Is there a list of possible frame/time sync algorithms or a paper to read into?
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Typically, you'll want to include the "current client tick" in each client-to-server message.
The server would record its tick as soon as it receives the message.
Then, when the server sends a message to the client, it will include the following information:
The last tick you sent was A. I received it at tick B. When I send you this message, it's now tick C.
The client can then use this information, plus the tick D at which it received the server update, to calculate an appropriate offset.
Alternatively, the client can just include its tick, and the server just includes "you were X ticks behind/ahead in the last message you sent" in the response. Beware overlapping adjustments that will make the client offset gyrate wildly, though. You can typically get pretty good with a simple algorithm:
• Each time you're more than 32 ticks off, adjust by one-quarter the amount in the appropriate direction.
• Each time you're more than 15 ticks off but less than 33, adjust by one-eighth the amount in the appropriate direction.
• Each time you're late by 0 to 15 ticks, adjust backward by one tick.
• Each time you're early by 1 to 7 ticks, leave it be. (Or some other value for "7" for how much jitter compensation you're prepared to accept.)
• Each time you're early by 8 to 15 ticks, adjust forward by one tick.
This will converge somewhat slowly, but is tolerant to "overshoot" where the server will keep sending you "you're late" messages for a bit after you make an adjustment, because of the latency and overlapping messages involved. There are of course other more stateful mechanisms, using generation counters or packet serial numbers or such, in the algorithm/protocol.
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8 hours ago, hplus0603 said:
Alternatively, the client can just include its tick, and the server just includes "you were X ticks behind/ahead in the last message you sent" in the response. Beware overlapping adjustments that will make the client offset gyrate wildly, though.
I just tried that. In a simple Unity Update Loop with two different flavors.
a) Advance the Simulation N-times if needed. But don't advance but adjust tick backwards if we are too far in the future.
ulong clientTick;
//not pretty
void Update() {
int offsetFromServer = GetLastServerOffset();
int ticksToSimulate = 0;
if(offset < -32) {
ticksToSimulate = (int) (Math.Abs(offset) * 1f/4f);
} else if(offset < -15) {
ticksToSimulate = (int) (Math.Abs(offset) * 1f/8f);
} else if(offset < 0) {
ticksToSimulate = 2;
} else if(offset > 32) {
clientTick -= (int) (offset * 1f/4f); //?
} else if(offset > 15) {
clientTick -= (int) (offset * 1f/8f); //?
} else if(offset > 8) {
clientTick -= 1; //?
} else {
//offset >= 0 && offset < 8
ticksToSimulate = 1;
}
if(ticksToSimulate > 0) {
SimulateFor(ticksToSimulate);
}
}
That.. well did not work as expected. Setting the clientTick to the past is also probably not a good idea?
b) Based on the offset adjust the time between ticks without touching the actual tickDelta for the simulation. If the client is too far behind Simulate() is called more often but still uses a fixed delta of 16ms internally.
ulong clientTick;
float tickRate = 1/60f;
double lastTickTime = 0;
//not pretty //Note hacky unity update running at 300fps+
void Update() {
if(lastTickTime + adjustedTickRate <= Time.time) {
int offsetFromServer = GetLastServerOffset();
if(offset < -32) {
} else if(offset < -15) {
} else if(offset < 0) {
} else if(offset > 32) {
} else if(offset > 15) {
} else if(offset > 8) {
} else {
}
Simulate();
lastTickTime = Time.time;
}
}
Do you have any pointers on how to adjust the client tick in a better way? Did you have something like this in your mind?
Both versions seem to need a fail-safe of either setting the clienttick to nearly the server tick if it is too far off and the second version (b) needs a very long time to adjust the client tick to ~ the server tick. Maybe mix both versions?
Another thing bugging my mind is: Should I take the RTT into account and recalculate the offset on the client side before using it for adjustments? Like a "hey I already did that adjustment in the last frame, I should be fine"-kinda way.
Cheers
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Like a "hey I already did that adjustment in the last frame, I should be fine"-kinda way.
Yes, that's the "danger of adjusting too much because of overlapping outstanding messages" problem I talked about. There are multiple ways to implement that.
Another way would be to send your current tick and your current offset to the server, and the server would then send a recommended offset back. That would let you adjust without the risk of oscillation.
Or you can go all science on the problem and look at the NTP protocol (or PTP) although those protocols solve a slightly different problem. For games, all that matters is that events happen in the same order, and inputs arrive at the server ahead of the time they're needed, which means that clock skew in one direction is much worse than clock skew in the other direction.
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On 5/8/2018 at 6:58 AM, poettlr said:
So for now my last big problem will be client/server time synchronization
If it's of any help, I just implemented this recently: https://pastebin.com/EaAK9Fce
After connecting, the client starts sending timestamped messages to the server periodically, which include it's own clock value and a guess of the server's clock value. The server responds by sending the client's clock value back to them, along with the server's actual clock value, and the error between that and their guess.
The client can compare their own clock at the time of receipt to their clock value included in the packet to measure the RTT. They can use the server's clock value to compute a delta between the client/server clocks (allowing them to convert times on one clock to times on the other), and can use the "guess error" value to tell how well calibrated their last attempt was.
I keep collecting a lot of these deltas/errors, and then use some statistics to make an educated guess. Each time the client gets a new response, they push the computed delta and error values into some vectors. They then calculate the standard deviation and the median of each vector, and then calculate a 32% truncated mean (the average, but ignoring any values that are further than 1 std dev from the median)... They then report these means as the "correct" delta value to use when trying to convert between client/server clocks.
I also report a made up "confidence" score, which is weighted by now many samples it's based on (more timing packets = more confidence), how many passed the filter (less outliers / tighter distribution = more confidence), and the mean error value reported by the server (server reports that our guesses are fairly close = more confidence). Once my confidence score reaches some arbitrary threshold, I stop sending these timing packets and assume that the clock is synchronized.
If, at any point during gameplay, the client realizes that a packet has arrived at the client before it was sent from the server, then obviously our clock synchronization was wrong (the alternative of faster-than-light internet is less likely...) so the age of such packets is immediately subtracted from the clock sync delta to get it back to a plausible level. So far this situation has only popped up on LAN where the pings can drop extremely low
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Once my confidence score reaches some arbitrary threshold, I stop sending these timing packets and assume that the clock is synchronized.
Thanks for sharing!
You might want to keep the timing information in your general packet headers, to be able to adjust to changing network conditions (both lower and higher pings, as well as changing variance) on the fly, without having to see an "impossible" event. I imagine you can actually do this even for the initial set-up -- if timing is part of the packet headers, you don't need to explicitly send separate timing messages.
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10 hours ago, hplus0603 said:
You might want to keep the timing information in your general packet headers, to be able to adjust to changing network conditions
Yeah I guess that if you're sending ~1KB sized packets, a few bytes of timer info is a small overhead. If my syncing code works, the goal is to synchronise the two clocks globally, regardless of ping, etc. i.e. If you photograph the client/server screens simultaneously, you would hopefully see the exact same clock value. So if my code works initially, varying network conditions don't affect it
However, my code only seems to manage to achieve sync within a few dozen milliseconds, not complete accuracy... Which is enough error for time travelling events to be noticed on LAN and require corrections to the clock sync to be applied later
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In practice, you'll want sync to be such, that the packet from the client arrives at the server slightly ahead of when it's needed. The "slightly" value should typically be about three standard deviations of your jitter, so 99.7% of all packets arrive ahead of their being needed.
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× | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.2565344572067261, "perplexity": 2898.4165620728795}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-43/segments/1539583512836.0/warc/CC-MAIN-20181020142647-20181020164147-00079.warc.gz"} |
https://math.stackexchange.com/questions/1925710/necessary-and-sufficient-conditions-nehari | # Necessary and Sufficient Conditions - Nehari
I want to find necessary and sufficient conditions in order that the following problem has a solution:
Given complex numbers $a_0,\ldots,a_n$ consider the problem to find all complex function $f$, $$f(\lambda)=\sum_{\nu=0}^{\infty}{\lambda^\nu f_\nu},$$
satisfying the following three conditions:
• $f_j=a_j$ for $j=0,\ldots,n$;
• $\sum_{\nu=0}^{\infty}|f_\nu|<\infty$;
• $\sup_{\lambda\in \mathbb{D}}|f(\lambda)|<1,$ where $\mathbb{D}$ is the open unit disk in the complex plane.
First, I had no idea how to start, however after some research I found out that this problem looks similar to a Nehari extension problem. see: https://www.encyclopediaofmath.org/index.php/Nehari_extension_problem
Apparently, a lot is known about the Nehari extension problem. So, I have tried to reduce my problem to a Nehari EP to use the existence theorems, but have had no success. How can I transform this system into a Nehari extension problem?
Any hints are appreciated.
• Do you mean $\sup_\lambda |f(\lambda)|$? Supremum over what set? – Robert Israel Sep 13 '16 at 20:52
• @RobertIsrael Sorry. See edit. – KayL Sep 13 '16 at 21:00 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8465301394462585, "perplexity": 290.2486042765082}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-35/segments/1566027315321.52/warc/CC-MAIN-20190820092326-20190820114326-00254.warc.gz"} |
https://icml.cc/Conferences/2021/ScheduleMultitrack?event=12804 | Timezone: »
Subgaussian Importance Sampling for Off-Policy Evaluation and Learning
Alberto Maria Metelli · Alessio Russo · Marcello Restelli
Importance Sampling (IS) is a widely used building block for a large variety of off-policy estimation and learning algorithms. However, empirical and theoretical studies have progressively shown that vanilla IS leads to poor estimations whenever the behavioral and target policies are too dissimilar. In this paper, we analyze the theoretical properties of the IS estimator by deriving a probabilistic deviation lower bound that formalizes the intuition behind its undesired behavior. Then, we propose a class of IS transformations, based on the notion of power mean, that are able, under certain circumstances, to achieve a subgaussian concentration rate. Differently from existing methods, like weight truncation, our estimator preserves the differentiability in the target distribution. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8731130361557007, "perplexity": 945.9102902387538}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-49/segments/1669446711552.8/warc/CC-MAIN-20221209213503-20221210003503-00834.warc.gz"} |
https://healthmanagement.org/products/view/vertical-electrophoresis-chamber-for-dna-sequencing-phero-seq-3345-e-without-lid-biotec-fischer | ### Vertical electrophoresis chamber / for DNA sequencing PHERO-seq 3345-E without lid BIOTEC-FISCHER PHERO-seq 3345-E without lid
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The PHERO-seq 2050-E and PHERO-seq 3345-E are ideal for a variety of large format vertical gel applications, these units offer advanced features for enhancing gel resolution and ease of use, essential when handling gels of this size. Each unit contains ultra soft silicone seals for easy plate sealing and trouble free runs, even over extended run times. Resolution is enhanced by using an aluminium heat sink plate, essential for even sample migration. Added convenience is provided by a removable lower buffer tank and upper buffer drainage tap. Special buffer chambers allow either low buffer volumes to be used for economy or high buffer volumes to be used for extended runs. A wide range of interchangeable comb and spacer options allows a large number of techniques to be easily accomplished including; DNA Sequencing, 2-D analysis, Micro-satellite analysis, DNA fingerprinting, Gel shift assays, Single-Strand Conformation Polymorphism (SSCP), Heteroduplex and Oligonucleotide analysis.
a:2:{i:0;a:2:{s:4:"name";s:5:"Type:";s:3:"val";s:8:"vertical";}i:1;a:2:{s:4:"name";s:22:"Other characteristics:";s:3:"val";s:18:"for DNA sequencing";}}
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× × × × × × | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.856472909450531, "perplexity": 23762.46689081346}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-47/segments/1510934805265.10/warc/CC-MAIN-20171119023719-20171119043719-00739.warc.gz"} |
https://bitbucket.org/crcx/retro-language | # Retro Language
## Overview
Retro is a concatenative, stack-based programming language with roots in Forth. It is intended to be clean and practical.
All code, documentation, and any binaries included are provided under the ISC License unless otherwise noted in the source. Please feel free to take, use, and modify Retro as you see fit.
## Development
Development is managed using the Bazaar version control system. Our primary repository is hosted on Launchpad.net
You can obtain a current copy of the code by doing:
bzr branch lp:retro-language
We also publish hourly snapshots of the code to the website.
## Documentation
Retro comes with a variety of documents describing the language, virtual machine, and implementation details. Most of these are in ReStructured Text (ReST) format and can be converted to other formats using docutils. A stylesheet is included for HTML output.
## Getting Help
We have an irc channel on the freenode network. Join #retro on irc.freenode.net. If you ask a question, please be patient. We have large idle times, but the channel is logged (see http://rx-core.org/dev/rancid) and we generally try to answer questions in a reasonible time period.
You can also ask questions on the mailing list. Signups, and a public archive, are at http://groups.google.com/group/retro-10 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.15470072627067566, "perplexity": 3351.9557877262528}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-34/segments/1502886117519.92/warc/CC-MAIN-20170823035753-20170823055753-00400.warc.gz"} |
https://physics.stackexchange.com/questions/453616/derive-porosity-from-stiffness-value | # Derive Porosity from Stiffness Value
I have the Young's modulus (stiffness) values of a hydro-gel scaffolds, and I need to know the porosity of those scaffolds.
I read about Nielsen Equation, which is this: $$E = \frac{E_0 (1 - P) ^ 2}{1 + \frac{P}{f - 1}}$$ where $$E$$ is Young’s modulus, $$E_0$$ is Young’s modulus for pore-less sample, $$P$$ is volume fraction of porosities, and $$f$$ is shape factor.
I have the following questions:
1. How to get the values of $$f$$ and $$E_0$$?
2. Any other methods to calculate porosity given material stiffness?
• Although I don't have it on hand to check, you may find Gibson and Ashby's Cellular Solids helpful, as it links scaffold geometries to mechanical properties. – Chemomechanics Jan 11 at 22:40 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 7, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8154176473617554, "perplexity": 1064.7085766139514}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-13/segments/1552912203021.14/warc/CC-MAIN-20190323201804-20190323223804-00540.warc.gz"} |
https://planetmath.org/discretevaluationring | # discrete valuation ring
A discrete valuation ring $R$ is a principal ideal domain with exactly one nonzero maximal ideal $M$. Any generator $t$ of $M$ is called a uniformizer or uniformizing element of $R$; in other words, a uniformizer of $R$ is an element $t\in R$ such that $t\in M$ but $t\notin M^{2}$.
Given a discrete valuation ring $R$ and a uniformizer $t\in R$, every element $z\in R$ can be written uniquely in the form $u\cdot t^{n}$ for some unit $u\in R$ and some nonnegative integer $n\in\mathbb{Z}$. The integer $n$ is called the order of $z$, and its value is independent of the choice of uniformizing element $t\in R$.
Title discrete valuation ring Canonical name DiscreteValuationRing Date of creation 2013-03-22 12:16:40 Last modified on 2013-03-22 12:16:40 Owner djao (24) Last modified by djao (24) Numerical id 9 Author djao (24) Entry type Definition Classification msc 13F30 Classification msc 13H10 Synonym DVR Related topic LocalRing Related topic DiscreteValuation Related topic Valuation Defines uniformizer Defines uniformizing element Defines order | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 18, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.5589009523391724, "perplexity": 606.0598496408737}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-47/segments/1542039743248.7/warc/CC-MAIN-20181117020225-20181117042225-00527.warc.gz"} |
https://quantumcomputing.stackexchange.com/questions/8685/secret-sharing-though-quantum-operations | # Secret sharing though quantum operations
I have a secret say $$s$$. I have a dealer $$D$$ and three participants $$A, B, C$$. I want to share this secret $$s$$ in such a way that the participation of all $$3$$ is essential to reconstruct the secret. Now for creating the shares, I use some classical sharing algorithms and create shares $$s_A,s_B,s_C$$. Now how do I distribute these shares among the participants quantum mechanically using qudits? What I thought is the following steps.
First, let the basis be $$\{|0\rangle, |1\rangle,.....,|d-1\rangle\}.$$ Now since each of the participant $$A, B, C$$ has his/her share, one of them starts the reconstruction process by first preparing a $$|0\rangle$$ and taking its Fourier transform, so I get $$|\phi\rangle_1=\sum_{y=0}^{d-1}|y\rangle_1$$Now the next step is to initialize two $$|0\rangle$$ states and perform the CNOT gate on them with the first qudit as the control, so to get $$|\phi\rangle_2=\sum_{y=0}^{d-1}|y\rangle_1|y\rangle_2|y\rangle_3$$After this step we perform the Quantum Fourier transformation on all the particles to get $$|\phi\rangle_3=\sum_{y=0}^{d-1}\sum_{k_1=0}^{d-1}\sum_{k_2=0}^{d-1}\sum_{k_3=0}^{d-1}\omega^{(k_1+k_2+k_3)y}|k_1\rangle_1|k_2\rangle_2|k_3\rangle_3$$ Now since the summation is finite i rearrange the terms to get $$|\phi\rangle_3=\sum_{k_1=0}^{d-1}\sum_{k_2=0}^{d-1}\sum_{k_3=0}^{d-1}\sum_{y=0}^{d-1}\omega^{(k_1+k_2+k_3)y}|k_1\rangle_1|k_2\rangle_2|k_3\rangle_3$$ With $$\sum_{i=0}^{d-1}\omega^i=0$$, we have the condition that the state left after this operation will be subject to the condition that $$k_1+k_2+k_3=0\;mod\;d$$ , we will have $$|\phi\rangle_3=\sum_{k_1=0}^{d-1}\sum_{k_2=0}^{d-1}\sum_{k_3=0}^{d-1}|k_1\rangle_1|k_2\rangle_2|k_3\rangle_3$$
now after preparing this state each participant $$A,B,C$$ applies a transformation $$U_{s_B},U_{s_A},U_{s_C}$$ which gives the state as $$|\phi\rangle_3=\sum_{k_1=0}^{d-1}\sum_{k_2=0}^{d-1}\sum_{k_3=0}^{d-1}|k_1+s_A\rangle_1|k_2+s_B\rangle_2|k_3+ s_C\rangle_3$$ After peparing this state the state is returned by the participants to the dealer who measures state for the shares and if it is right then announces the result/secret. Now my questions are:
(i) Even though this is a very preliminary effort, can somebody tell me whether can we can actually do this?
(ii) My second question is if this is possible then can we improve this scheme to achieve the condition for the detection of a fraudulent participant? Can somebody help??
There is one main key point in the description of your question: Is $$s$$ meant to be a classical secret or a quantum secret?
If $$s$$ is meant to be a classical secret, then the answer is yes, but there is not really much quantum in the positive answer. If $$s_A$$, $$s_B$$, and $$s_C$$ are all $$d$$-state digits, then there is a simple construction that works in which $$s$$ is also a $$d$$-state digit. (There is also a simple argument that you cannot make $$s$$ any larger than this.) Namely, you should choose $$s_A$$ and $$s_B$$ uniformly and independently at random, and the then choose $$s_C$$ such that $$s = s_A + s_B + s_C$$ in the abelian group $$\mathbb{Z}/d$$. If you want to make this look quantum, then you can, because you store a digit in a qudit. You can turn $$s_A$$ into $$|s_A\rangle$$, etc. Then you are free to measure all three and take their sum, or just measure their sum. The problem with this answer is that you did more than necessary to share the secret. You only used the qudits as classical digits of the same size. This is like taking a million-dollar luxury car to the supermarket when you could have done the exact same thing with a \\$5,000 used car.
Let's say instead that $$s$$ is meant to be a quantum secret $$|s\rangle$$. Then first of all, your language for extracting the secret is not correct. If the dealer measures everything to gain the secret, then the result cannot be a quantum state $$|s\rangle$$, because everything has been measured and all quantum superposition is then gone. Moreover, the shares must be entangled for this to work, so they are not separate states $$|s_A\rangle$$, $$|s_B\rangle$$, and $$|s_C\rangle$$, but rather a joint state $$|s_{ABC}\rangle$$. To extract $$|s\rangle$$, the dealer must carefully apply some unitary operator to the joint state to get out $$|s\rangle$$ as a piece of some larger state, without measuring $$|s\rangle$$ itself.
So let's say those are the rules. We can go back and borrow a different concept from classical secret-sharing. Namely, instead of 3 parties we may have $$\ell$$ parties. Instead of saying that we need all of the parties together to learning everything and with any fewer we know nothing, we can have the weaker condition that for some $$t < \ell$$, any set of $$t$$ or fewer parties cannot say anything about the secret. Then there is a remarkable fact that a quantum secret-sharing with these rules is exactly the same thing as a quantum error-correcting code (QECC) of length $$\ell$$ using $$d$$-state qudits, with minimum error distance $$t+1$$. Classical error correction is in a natural sense dual to classical secret-sharing. Quantum error correction turns out to be a self-dual problem that is the same as quantum secret-sharing.
If we take the original question in its quantum form, the question becomes finding a QECC of length 3 with $$d$$-state qudits and minimum distance 3. I don't think that any such code exists that can store any non-trivial information, although I would have to do some review to remember how to prove that. I don't even expect there to be such a code with minimum distance 2 (so that only each individual party has no glimpse of the secret) if you want to the secret to have as many as $$d$$ states when $$d=2$$. I can check this in the special class of additive codes, and I can say non-rigorously that additive codes are sometimes optimal. However, if the parameters are $$\ell = 3$$, $$t = 2$$, and $$d$$ an odd integer, then I think that there is an additive QECC of this type. We can assume that $$d=p$$ is prime (because otherwise we can factor $$d$$ and make separate codes). Then we can choose three non-zero exponents $$s,t,u \in \mathbb{Z}/p$$ that sum to zero, and we can make a quantum code that stores one qudit using the quantum parity checks $$X \otimes X \otimes X$$ and $$Z^s \otimes Z^t \otimes Z^u$$. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 63, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8916131258010864, "perplexity": 228.46829697281515}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-31/segments/1627046154175.76/warc/CC-MAIN-20210801092716-20210801122716-00270.warc.gz"} |
http://cvgmt.sns.it/paper/3219/ | # Continuity for the Monge mass transfer problem in two dimensions
created by santambro on 27 Oct 2016
modified on 29 Jul 2018
[BibTeX]
Accepted Paper
Inserted: 27 oct 2016
Last Updated: 29 jul 2018
Journal: Arch. Rati. Mech. An.
Year: 2018
Notes:
-- Second and strongly revised version --
Abstract:
In this paper, we prove the continuity of the monotone optimal mapping of the Monge mass transfer problem in two dimensions under certain conditions on the domains and the mass distributions. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8804009556770325, "perplexity": 4662.546048784745}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-43/segments/1539583516480.46/warc/CC-MAIN-20181023153446-20181023174946-00443.warc.gz"} |
https://gemseo.readthedocs.io/en/stable/_modules/gemseo.problems.sobieski.core.problem.html | gemseo / problems / sobieski / core
problem module¶
The Sobieski’s SSBJ problem.
class gemseo.problems.sobieski.core.problem.SobieskiProblem(dtype='float64')[source]
Bases: object
The Sobieski’s SSBJ problem.
This problem seeks to maximize the range of a supersonic business jet (SSBJ) over a bounded design space whilst satisfying inequality constraints.
The objective and constraint functions come from a system of four disciplines:
1. the structure, computing the total aircraft mass $$y_{1,4,0}$$ and $$y_{1,2,0}$$, the fuel mass $$y_{1,4,1}$$, the wing twist $$y_{1,2,1}$$ and the five stress constraints $$g_{1,0},\ldots,g_{4,0}$$.
2. the aerodynamics discipline, computing the lift $$y_{2,1}$$, drag $$y_{2,3}$$, lift-to-drag ratio and pressure gradient constraint $$g_2$$,
3. the propulsion, computing the engine mass $$y_{3,1,0}$$, the engine scale factor $$y_{3,2,0}$$, which is also the constraint $$g_{3,0}$$, the specific fuel consumption $$y_{3,4,0}$$, the engine temperature constraint $$g_{3,1}$$, and the throttle setting constraint $$g_{3,2}$$
4. the mission, computing the range $$y_{4,0}$$.
Notes
• The structure, aerodynamics, propulsion and mission disciplines are numbered from 1 to 4.
• The variable $$y_{i,j,k}$$ is a coupling variable from the discipline $$i$$ to the discipline $$j$$.
• The aerodynamics, structure and propulsion disciplines are strongly coupled, i.e. each of them depends directly or indirectly on the others, and provide inputs to the mission discipline.
The design variables can be classified into four groups:
• the design variables which are inputs to at least two disciplines,
• $$x_{0,0}$$: the thickness-to-chord ratio,
• $$x_{0,1}$$: the altitude (ft),
• $$x_{0,2}$$: the Mach number,
• $$x_{0,3}$$: the aspect ratio,
• $$x_{0,4}$$: the wing sweep (deg),
• $$x_{0,5}$$: the wing surface area (ft 2),
• the design variables which are inputs of the structure discipline only:
• $$x_{1,0}$$: the wing taper ratio,
• $$x_{1,1}$$: the wingbox x-sectional area
• the design variables which are inputs of the aerodynamics discipline only:
• $$x_{2,0}$$: the skin friction coefficient,
• the design variables which are inputs of the propulsion discipline only:
• $$x_{3,0}$$: the throttle setting (engin mass flow).
Lastly, this problem is based on five constants:
• $$c_0$$: the minimum fuel weight,
• $$c_1$$: the miscellaneous weight,
• $$c_2$$: the maximum load factor,
• $$c_3$$: the reference engine weight,
• $$c_4$$: the minimum drag coefficient.
Parameters:
dtype (str) –
The data type for the NumPy arrays, either “float64” or “complex128”.
By default it is set to “float64”.
get_bounds_by_name(variables_names)[source]
Return the lower and upper bounds of variables.
Parameters:
variables_names (Sequence[str]) – The names of the variables.
Returns:
The lower and upper bounds of the variables; the array components keep the order of the variables.
Return type:
get_constraints(design_vector, true_cstr=False)[source]
Compute all the constraints.
Parameters:
• design_vector (ndarray) – The design vector.
• true_cstr (bool) –
If True, return the value of the constraint outputs. Otherwise, return the distance to the corresponding constraint thresholds.
By default it is set to False.
Returns:
The value of the constraints $$g_1$$, $$g_2$$ and $$g_3$$.
Return type:
get_default_inputs(names=None)[source]
Return the default variable values at the default initial point.
Parameters:
names (str | Iterable[str] | None) – The names of the variables of interest. If None, use all the variables of the problem.
Returns:
The default values of some variables at the default initial point.
Return type:
dict[str, ndarray]
get_default_inputs_equilibrium(names=None)[source]
Return the default variable values at a multidisciplinary feasible point.
The coupling variables are at the equilibrium, in the sense of the multidisciplinary analysis (MDA).
Parameters:
names (str | Iterable[str] | None) – The names of the variables of interest. If None, use all the variables of the problem.
Returns:
The default values of some variables at a multidisciplinary feasible point.
Return type:
dict[str, ndarray]
get_default_inputs_feasible(names=None)[source]
Return the default variable values at the default initial feasible point.
Parameters:
names (str | Iterable[str] | None) – The names of the variables of interest. If None, use all the variables of the problem.
Returns:
The default values of some variables at the default initial feasible point.
Return type:
dict[str, ndarray]
get_random_input(names=None, seed=None)[source]
Return a randomized starting point related to some input variables.
Parameters:
• names (str | Iterable[str] | None) – The names of the variables. If None, use all the input variables.
• seed (int | None) – The seed for the random number generation. If None, do not set the seed.
Returns:
The randomized starting point.
Return type:
ndarray
get_sobieski_constraints(g_1, g_2, g_3, true_cstr=False)[source]
Return either the value of the constraints or the distance to the thresholds.
Parameters:
• g_1 (ndarray) – The constraints from the structure discipline: g_1[0] to g_1[4] are the stresses on wing and g_1[5] is the wing twist.
• g_2 (ndarray) – The constraint (pressure gradient) from the aerodynamics discipline.
• g_3 (ndarray) –
The constraints from the propulsion discipline: g_3[0] is the engine scale factor,
g_3[1] is the engine temperature and g_3[2] is the throttle setting constraint.
• true_cstr (ndarray) –
If True, return the value of the outputs. Otherwise, return the distance to the corresponding constraint thresholds.
By default it is set to False.
Returns:
The constraints or the distance to the thresholds, according to true_cstr.
Return type:
ndarray
get_x0_feasible(names=None)[source]
Return a feasible starting point related to some input variables.
Parameters:
names (str | Iterable[str] | None) – The names of the variables. If None, use all the input variables.
Returns:
The feasible starting point.
Return type:
ndarray
normalize_inputs(input_vector)[source]
Normalize an input vector with respect to the variable bounds.
Parameters:
input_vector (ndarray) – The input vector.
Returns:
The normalized input vector with components in $$[0,1]$$.
Return type:
ndarray
unnormalize_inputs(input_vector)[source]
Unnormalize an input vector with respect to the variable bounds.
Parameters:
input_vector (ndarray) – The normalized input vector.
Returns:
The input vector in the variable space.
Return type:
ndarray
CONTRAINTS_NAMES = ('Stress_x1', 'Stress_x2', 'Stress_x3', 'Stress_x4', 'Stress_x5', 'Twist', 'Pgrad', 'ESF', 'Temperature', 'Throttle')
CONTRAINTS_NAMES_INEQUALITY = ('c_Stress_x1', 'c_Stress_x2', 'c_Stress_x3', 'c_Stress_x4', 'c_Stress_x5', 'c_Twist_upper', 'c_Twist_lower', 'c_Pgrad', 'c_ESF_upper', 'c_ESF_lower', 'c_Throttle', 'c_Temperature')
COUPLING_VARIABLES_NAMES = ('Total weight', 'Fuel weight', 'Wing twist', 'Lift', 'Drag', 'Lift/Drag', 'SFC', 'Engine weight')
DV_NAMES = ('TaperRatio', 'SectionalArea', 'Cf', 'Throttle_setting', 'eta', 'h', 'Mach', 'AR', 'Phi', 'sref')
DV_NAMES_NORMALIZED = ('x_TaperRatio', 'x_SectionalArea', 'x_Cf', 'x_Throttle_setting', 'x_eta', 'x_h', 'x_Mach', 'x_AR', 'x_Phi', 'x_sref')
ESF_LOWER_LIMIT = 0.5
ESF_UPPER_LIMIT = 1.5
STRESS_LIMIT = 1.09
TEMPERATURE_LIMIT = 1.02
TWIST_LOWER_LIMIT = 0.8
TWIST_UPPER_LIMIT = 1.04
USE_ORIGINAL_DESIGN_VARIABLES_ORDER: ClassVar[bool] = False
Whether to sort the DesignSpace as in [SSAJr98].
If so, the order of the design variables will be "x_1", "x_2", "x_3" and "x_shared". Otherwise, "x_shared", "x_1", "x_2" and "x_3".
property aerodynamics: SobieskiAerodynamics
The aerodynamics discipline.
property constants: ndarray
The constant vector.
property design_bounds: tuple[numpy.ndarray, numpy.ndarray]
The lower and upper bounds of the design variables.
property design_space: DesignSpace
The design space.
property design_space_with_physical_naming: DesignSpace
The design space with physical naming.
property initial_design: ndarray
The initial design $$x$$.
property mission: SobieskiMission
The mission discipline.
property optimum_design: ndarray
The optimal design vector found by Sobieski with BLISS.
property optimum_range: ndarray
The optimal range found by Sobieski with BLISS.
property propulsion: SobieskiPropulsion
The propulsion discipline.
property structure: SobieskiStructure
The structure discipline.
Examples using SobieskiProblem¶
Basic history
Basic history
Constraints history
Constraints history
Correlations
Correlations
Gantt Chart
Gantt Chart
Objective and constraints history
Objective and constraints history
Optimization History View
Optimization History View
Parallel coordinates
Parallel coordinates
Pareto front
Pareto front
Robustness
Robustness
Scatter plot matrix
Scatter plot matrix
Self-Organizing Map
Self-Organizing Map
Variables influence
Variables influence
Scalable diagonal discipline
Scalable diagonal discipline
Plug a surrogate discipline in a Scenario
Plug a surrogate discipline in a Scenario
BiLevel-based DOE on the Sobieski SSBJ test case
BiLevel-based DOE on the Sobieski SSBJ test case
BiLevel-based MDO on the Sobieski SSBJ test case
BiLevel-based MDO on the Sobieski SSBJ test case
IDF-based MDO on the Sobieski SSBJ test case
IDF-based MDO on the Sobieski SSBJ test case
MDF-based DOE on the Sobieski SSBJ test case
MDF-based DOE on the Sobieski SSBJ test case
MDF-based MDO on the Sobieski SSBJ test case
MDF-based MDO on the Sobieski SSBJ test case
Application: Sobieski’s Super-Sonic Business Jet (MDO)
Application: Sobieski's Super-Sonic Business Jet (MDO)
Simple disciplinary DOE example on the Sobieski SSBJ test case
Simple disciplinary DOE example on the Sobieski SSBJ test case
Empirical estimation of statistics
Empirical estimation of statistics | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.4967414438724518, "perplexity": 16684.570274336227}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2023-06/segments/1674764500154.33/warc/CC-MAIN-20230204205328-20230204235328-00252.warc.gz"} |
https://link.springer.com/article/10.1007/s00211-016-0838-6 | Numerische Mathematik
, Volume 136, Issue 1, pp 215–248
# Ultraconvergence of high order FEMs for elliptic problems with variable coefficients
• Wen-ming He
• Zhimin Zhang
• Qingsong Zou
Article
## Abstract
In this paper, we investigate local ultraconvergence properties of the high-order finite element method (FEM) for second order elliptic problems with variable coefficients. Under suitable regularity and mesh conditions, we show that at an interior vertex, which is away from the boundary with a fixed distance, the gradient of the post-precessed kth $$(k\ge 2)$$ order finite element solution converges to the gradient of the exact solution with order $$\mathcal{O}(h^{k+2} (\mathrm{ln} h)^3)$$. The proof of this ultraconvergence property depends on a new interpolating operator, some new estimates for the discrete Green’s function, a symmetry theory derived in [26], and the Richardson extrapolation technique in [20]. Numerical experiments are performed to demonstrate our theoretical findings.
## Mathematics Subject Classification
65N30 65N25 65N15
## Notes
### Acknowledgments
The authors would like to thank both the anonymous referees for their careful reading of the paper and their valuable comments which leads to a significant improvement of the paper. The first author is supported in part by the National Natural Science Foundation of China (11671304, 11171257, 11301396), the Zhejiang Provincial Natural Science Foundation, China (No. LY15A010015). The second author is supported in part by the National Natural Science Foundation of China (11471031,91430216) and the US National Science Foundation through grant U1530401. The third author is supported in part by the National Natural Science Foundation of China through grants 11571384 and 11428103, by the Fundamental Research Funds for the Central Universities through grant 16lgjc80, and by Guangdong Provincial Natural Science Foundation of China through grant 2014A030313179.
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# Combustion chamber of CFM model didn't burn
Experimenter
Hi, I'm using the IFP library to build a model of Turbocharged CNG Gasoline Engine. But currently i've found that after i added the turbo group , the CFM combustion chamber didn't burn. All the parameters i've set seem normal . Are there other parameters that can effect the combustion deeply?
# Re: Combustion chamber of CFM model didn't burn
Siemens Valued Contributor
Hi,
Adding a turbocharger should not change the combustion phasing. It will increase the intake mass flow rate and so, increase the volumetric efficiency. In the CFM combustion chambers, the turbulence maps (cut-off/tumble) are function of the volumetric efficiency.
I recommend to:
- check if the volumetric efficiency is correct,
- check if your turbulence maps are defined for those values (if not, a linear extrapoaltion is done and can lead to inconsistent values)
Cordially,
Thomas | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8423675894737244, "perplexity": 4617.023110602814}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-05/segments/1516084890795.64/warc/CC-MAIN-20180121155718-20180121175718-00176.warc.gz"} |
http://mathhelpforum.com/algebra/154459-sigma-notation.html | # Math Help - sigma notation
1. ## sigma notation
how to write in correct way:
to calculate the sum of odd numbers between 1 and n;
to calculate the sum of even numbers between 2 and n;
n
E (i+2) --> do you agree?
i=2
2. I would say, for even numbers:
$\sum_{i=0}^{n}(2i+2)$
and for odd:
$\sum_{i=0}^{n}(2i+1)$
how to write in correct way:
to calculate the sum of odd numbers between 1 and n;
to calculate the sum of even numbers between 2 and n;
n
E (i+2) --> do you agree?
i=2
$\displaystyle\sum_{i=2}^n(i+2)=4+5+6+.....+(n-1)+n+(n+1)+(n+2)$
$\displaystyle\sum_{i=1}^{\frac{n+1}{2}}(2i-1)=1+3+5+...+n$
or
$\displaystyle\sum_{i=0}^{\frac{n-1}{2}}(2i+1)=1+3+5+...+n$
for n even, sum of the odd numbers is...
$\displaystyle\sum_{i=1}^{\frac{n}{2}}(2i-1)=1+3+5+...+(n-1)$
or
$\displaystyle\sum_{i=0}^{\frac{n-2}{2}}(2i+1)=1+3+5+...+(n-1)$
That's if "between" is meant to include i=1 and i=n, rather than exclude them | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 7, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9697790741920471, "perplexity": 2328.0764207933466}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-41/segments/1410657137190.70/warc/CC-MAIN-20140914011217-00266-ip-10-234-18-248.ec2.internal.warc.gz"} |
https://www.physicsforums.com/threads/white-green-blue-vitriol.156428/ | # White/Green/Blue Vitriol
1. Feb 15, 2007
### chaoseverlasting
I need to find the structure of$$CuSO_4.5H_2O$$, $$ZnSO_4.7H_2O$$ and $$FeSO_4.7H_2O$$.
Ive looked at J.D. Lee for them but cant seem to find them, maybe im looking in the wrong place. I cant find something worthwhile on the net either. All I seem to hit are actual pictures of the salts/solutions but not the actual structure. Please help. If you can point out a link or something, Id be really greatful.
2. Feb 15, 2007
### chaoseverlasting
3. Feb 15, 2007
### chemisttree
If so, try searching for X-ray crystal structure of...
4. Feb 16, 2007
### chaoseverlasting
no... that not what im looking for... im looking for the molecular structure...
5. Feb 16, 2007
### chemisttree
The molecular structure in the crystal form will be presented as the X-Ray crystal structure. The molecular structure for ionic compounds is fairly meaningless in solution. The ions dissociate and are usually surrounded by solvent molecules. That fraction that is present in solution in undissociated form is actually continuously forming ions; said ions are continuously reforming undissociated species.
Different solvents or ligands may have different crystal fields and solvent shells which result in different arrangements of ligands/solvent around ions. This phenomenon gives rise to ionic species that have different spectral properties in differing solvents or with different ligands. Search on Debye Huckel Theory, Crystal Field Theory and 10DQ.
6. Feb 17, 2007
### chaoseverlasting
Yeah, I think its the Lewis structure Im looking for. Like diborane has the sturcture with the banana bonds (3c-2e bonds).
7. Feb 18, 2007
### chaoseverlasting
Nobody knows the molecular structure??? Im not talking about the structure in solution... the anhydrous form....
8. Feb 20, 2007
### chemisttree
Review the rules for determining Lewis structures.
If you are having difficulty, google "lewis dot structures". There are useful resources that will assist you.
Similar Discussions: White/Green/Blue Vitriol | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.3082389831542969, "perplexity": 4882.161585857262}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-13/segments/1490218189686.31/warc/CC-MAIN-20170322212949-00479-ip-10-233-31-227.ec2.internal.warc.gz"} |
https://yozh.org/2011/08/22/mmm047/ | # MMM XLVII
## Image Details
This is actually an image of the normal, everyday, run-of-the-mill Mandelbrot set that I first introduced last year. However, there is one small alteration. Before applying the iteration function, each point on the plane is mapped to its inverse. For instance, the point $$0.5+0.5i$$ is mapped to $$1.0-1.0i$$. Note that
$$(0.5+0.5i)(1.0-1.0i) = 0.5 – 0.5i + 0.5i – 0.5i^2 = 1,$$
hence the two points are inverses, as they multiply to 1.
This process of mapping points to their inverses has the effect of (more or less) turning the Mandelbrot set “inside-out.” Now the large whitish region that surrounds the image is made up of points in the Mandelbrot set, while the more colorful regions are actually outside of the set. What this means is that we should still be able to find some of the regions of interest which have been identified in previous posts.
For instance, this image contains a seahorse valley. If you look very carefully at the leftmost portion of the larger image (linked above—approx. 11.7 MB), you should be able to spot it. The seahorses are lined up on the left side of the valley. On the other end of the image, trailing off to point, there is a parade of elephants. Other recognizable features may present themselves, though the resolution of the image and the number of iterations may limit our ability to actually spot them.
This entry was posted in MMM and tagged , , . Bookmark the permalink. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6667217016220093, "perplexity": 490.30172842085545}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-21/segments/1620243992440.69/warc/CC-MAIN-20210517180757-20210517210757-00245.warc.gz"} |
https://www.aimsciences.org/article/doi/10.3934/krm.2015.8.309 | # American Institute of Mathematical Sciences
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June 2015, 8(2): 309-333. doi: 10.3934/krm.2015.8.309
## On the homogeneous Boltzmann equation with soft-potential collision kernels
1 Department of Mathematics, College of Natural Sciences, Chung-Ang University, 84 Heukseok-Ro, Dongjak-Gu, Seoul 156-756
Received August 2014 Revised January 2015 Published March 2015
We consider the well-posedness problem for the space-homogeneous Boltzmann equation with soft-potential collision kernels. By revisiting the classical Fourier inequalities and fractional integrals, we deduce a set of bilinear estimates for the collision operator on the space of integrable functions possessing certain degree of smoothness and we apply them to prove the local-in-time existence of a solution to the Boltzmann equation in both integral form and the original one. Uniqueness and stability of solutions are also established.
Citation: Yong-Kum Cho. On the homogeneous Boltzmann equation with soft-potential collision kernels. Kinetic and Related Models, 2015, 8 (2) : 309-333. doi: 10.3934/krm.2015.8.309
##### References:
[1] R. Alexandre, L. Desvillettes, C. Villani and B. Wennberg, Entropy dissipation and long-range interactions, Arch. Ration. Mech. Anal., 152 (2000), 327-355. doi: 10.1007/s002050000083. [2] L. Arkeryd, On the Boltzmann equation, Part I: Existence, Part II: The full initial value problem, Arch. Rational Mech. Anal., 45 (1972), 1-16. [3] L. Arkeryd, Intermolecular forces of infinite range and the Boltzmann equation, Arch. Rational Mech. Anal., 77 (1981), 11-21. doi: 10.1007/BF00280403. [4] F. Bouchut and L. Desvillettes, A proof of the smoothing properties of the positive part of Boltzmann's kernel, Rev. Mat. Iberoamericana, 14 (1998), 47-61. doi: 10.4171/RMI/233. [5] A. V. Bobylev, Fourier transform method in the theory of the Boltzmann equation for Maxwell molecules, Dokl. Akad. Nauk SSSR, 225 (1975), 1041-1044. [6] E. Carlen, M. Carvalho and X. Lu, On strong convergence to equilibrium for the Boltzmann equation with soft potentials, J. Stat. Phys., 135 (2009), 681-736. doi: 10.1007/s10955-009-9741-1. [7] C. Cercignani, R. Illner and M. Pulvirenti, The Mathematical Theory of Dilute Gases, Springer-Verlag, New York, 1994. doi: 10.1007/978-1-4419-8524-8. [8] Y.-K. Cho and H. Yun, On the gain of regularity for the positive part of Boltzmann collision operator associated with soft potentials, Kinetic and Related Models, 5 (2012), 769-786. doi: 10.3934/krm.2012.5.769. [9] L. Desvillettes and C. Mouhot, Stability and uniqueness for the spatially homogeneous Boltzmann equation with long-range interactions, Arch. Rational Mech. Anal., 193 (2009), 227-253. doi: 10.1007/s00205-009-0233-x. [10] N. Fournier and G. Héléne, On the uniqueness for the spatially homogeneous Boltzmann equation with a strong angular singularity, J. Stat. Phys., 131 (2008), 749-781. doi: 10.1007/s10955-008-9511-5. [11] L. Grafakos, On multilinear fractional integrals, Studia Math., 102 (1992), 49-56. [12] T. Goudon, On Boltzmann equations and Fokker-Planck asymptotics: Influence of grazing collisions, J. Stat. Phys., 89 (1997), 751-776. doi: 10.1007/BF02765543. [13] C. Kenig and E. M. Stein, Multilinear estimates and fractional integration, Math. Research Letters, 6 (1999), 1-15. doi: 10.4310/MRL.1999.v6.n1.a1. [14] P.-L. Lions, Compactness in Boltzmann's equation via Fourier integral operators and applications, I, II, J. Math. Kyoto Univ., 34 (1994), 391-427, 429-461. [15] X. Lu and Y. Zhang, On nonnegativity of solutions of the Boltzmann equation, Transport Theor. Stat., 30 (2001), 641-657. doi: 10.1081/TT-100107420. [16] S. Mischler and B. Wennberg, On the spatially homogeneous Boltzmann equation, Ann. Inst. Henri Poincaré, 16 (1999), 467-501. doi: 10.1016/S0294-1449(99)80025-0. [17] C. Mouhot and C. Villani, Regularity theory for the spatially homogeneous Boltzmann equation with cut-off, Arch. Rational Mech. Anal., 173 (2004), 169-212. doi: 10.1007/s00205-004-0316-7. [18] K. T. Smith, Primer of Modern Analysis, Springer-Verlag, New York, 1983. [19] E. M. Stein, Singular Integrals and Differentiabilty Properties of Functions, Princeton Univ. Press, 1970. [20] E. M. Stein, Harmonic Analysis: Real-Variable Methods, Orthogonality, and Oscillatory Integrals, Princeton Univ. Press, 1993. [21] C. Villani, On a new class of weak solutions to the spatially homogeneous Boltzmann and Landau equations, Arch. Rational Mech. Anal., 143 (1998), 273-307. doi: 10.1007/s002050050106. [22] C. Villani, A review of mathematical topics in collisional kinetic theory, in Handbook of Mathematical Fluid Dynamics, Vol. I, North-Holland, Amsterdam, 2002, 71-305. doi: 10.1016/S1874-5792(02)80004-0.
show all references
##### References:
[1] R. Alexandre, L. Desvillettes, C. Villani and B. Wennberg, Entropy dissipation and long-range interactions, Arch. Ration. Mech. Anal., 152 (2000), 327-355. doi: 10.1007/s002050000083. [2] L. Arkeryd, On the Boltzmann equation, Part I: Existence, Part II: The full initial value problem, Arch. Rational Mech. Anal., 45 (1972), 1-16. [3] L. Arkeryd, Intermolecular forces of infinite range and the Boltzmann equation, Arch. Rational Mech. Anal., 77 (1981), 11-21. doi: 10.1007/BF00280403. [4] F. Bouchut and L. Desvillettes, A proof of the smoothing properties of the positive part of Boltzmann's kernel, Rev. Mat. Iberoamericana, 14 (1998), 47-61. doi: 10.4171/RMI/233. [5] A. V. Bobylev, Fourier transform method in the theory of the Boltzmann equation for Maxwell molecules, Dokl. Akad. Nauk SSSR, 225 (1975), 1041-1044. [6] E. Carlen, M. Carvalho and X. Lu, On strong convergence to equilibrium for the Boltzmann equation with soft potentials, J. Stat. Phys., 135 (2009), 681-736. doi: 10.1007/s10955-009-9741-1. [7] C. Cercignani, R. Illner and M. Pulvirenti, The Mathematical Theory of Dilute Gases, Springer-Verlag, New York, 1994. doi: 10.1007/978-1-4419-8524-8. [8] Y.-K. Cho and H. Yun, On the gain of regularity for the positive part of Boltzmann collision operator associated with soft potentials, Kinetic and Related Models, 5 (2012), 769-786. doi: 10.3934/krm.2012.5.769. [9] L. Desvillettes and C. Mouhot, Stability and uniqueness for the spatially homogeneous Boltzmann equation with long-range interactions, Arch. Rational Mech. Anal., 193 (2009), 227-253. doi: 10.1007/s00205-009-0233-x. [10] N. Fournier and G. Héléne, On the uniqueness for the spatially homogeneous Boltzmann equation with a strong angular singularity, J. Stat. Phys., 131 (2008), 749-781. doi: 10.1007/s10955-008-9511-5. [11] L. Grafakos, On multilinear fractional integrals, Studia Math., 102 (1992), 49-56. [12] T. Goudon, On Boltzmann equations and Fokker-Planck asymptotics: Influence of grazing collisions, J. Stat. Phys., 89 (1997), 751-776. doi: 10.1007/BF02765543. [13] C. Kenig and E. M. Stein, Multilinear estimates and fractional integration, Math. Research Letters, 6 (1999), 1-15. doi: 10.4310/MRL.1999.v6.n1.a1. [14] P.-L. Lions, Compactness in Boltzmann's equation via Fourier integral operators and applications, I, II, J. Math. Kyoto Univ., 34 (1994), 391-427, 429-461. [15] X. Lu and Y. Zhang, On nonnegativity of solutions of the Boltzmann equation, Transport Theor. Stat., 30 (2001), 641-657. doi: 10.1081/TT-100107420. [16] S. Mischler and B. Wennberg, On the spatially homogeneous Boltzmann equation, Ann. Inst. Henri Poincaré, 16 (1999), 467-501. doi: 10.1016/S0294-1449(99)80025-0. [17] C. Mouhot and C. Villani, Regularity theory for the spatially homogeneous Boltzmann equation with cut-off, Arch. Rational Mech. Anal., 173 (2004), 169-212. doi: 10.1007/s00205-004-0316-7. [18] K. T. Smith, Primer of Modern Analysis, Springer-Verlag, New York, 1983. [19] E. M. Stein, Singular Integrals and Differentiabilty Properties of Functions, Princeton Univ. Press, 1970. [20] E. M. Stein, Harmonic Analysis: Real-Variable Methods, Orthogonality, and Oscillatory Integrals, Princeton Univ. Press, 1993. [21] C. Villani, On a new class of weak solutions to the spatially homogeneous Boltzmann and Landau equations, Arch. Rational Mech. Anal., 143 (1998), 273-307. doi: 10.1007/s002050050106. [22] C. Villani, A review of mathematical topics in collisional kinetic theory, in Handbook of Mathematical Fluid Dynamics, Vol. I, North-Holland, Amsterdam, 2002, 71-305. doi: 10.1016/S1874-5792(02)80004-0.
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2020 Impact Factor: 1.432 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8221824169158936, "perplexity": 2252.095636578796}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-21/segments/1652662519037.11/warc/CC-MAIN-20220517162558-20220517192558-00785.warc.gz"} |
http://www.emis.de/classics/Erdos/cit/20400905.htm | ## Zentralblatt MATH
Publications of (and about) Paul Erdös
Zbl.No: 204.00905
Autor: Erdös, Paul; Rado, R.
Title: Partition relations and transitivity domains of binary relations (In English)
Source: J. Lond. Math. Soc. 42, 624-633 (1967).
Review: The main theorem is Theorem 2: For all positive integers m and n, for some positive integer l(m,n), for each ordinal number \alpha, \omega\alpha l(m,n) ––> (m,\omega\alpha n)2; if l\alpha(m,n) is the least such l(m,n) for a given \alpha, then \gamma \mapsto(m,\omega\alpha n)2 for each \gamma > \omega\alpha l\alpha (m,n), and
l\alpha(m,n) \leq (2n-3)-1[2m-1(n-1)m+n-2];
if m > 1, then l0(m,n) \leq l\alpha (m,n).
This generalizes some of Theorem 1, which handles the case \alpha = 0 and was proved by the same authors [Bull. Am. Math. Soc. 62, 427-489 (1956; Zbl 071.05105), Theorem 25]; Theorem 1 includes also a characterization of l0(m,n). Among other results, Theorem 4 is an extension (the statement of which is not the obvious one) to infinite a of a result attributed to R. Stearns: If a is a finite cardinal, if \prec is a relation trichotomous on a set S, then \prec is transitive on some subset of S having cardinal a provided that |S| \geq 2n-1.
{Reviewer's remarks:
(1) It is easily seen that l0(m,2) as characterized by Theorem 1 is the least integer l such that for each set S with cardinal \geq l, for each relation \prec trichotomous on S, \prec is transitive on some subset of S having cardinal a. Specializing the estimate for l\alpha (m,n) in Theorem 2 to n = 2 yields the Stearns result.
(2) Theorem 1 is slightly misstated. If m = 1, \gamma \mapsto (m,\omega0n)2'' should be changed by replacing \gamma by \omega0(l0(m,n)-1).
(3) In the footnote on p. 625 (n-1)\mu'' should be replaced by (2(n-1))\mu''.
(4) On p. 627, (i) is not quite adequate but becomes so on replacing for x in A'\beta'', by for each x in A'\beta and |U0(x)A\gamma| = \aleph\alpha for some x in A\beta'', and (ii) is not quite adequate but becomes so on inserting and |U0(x)A\gamma| < \aleph\alpha for some x in A\beta'' after |U0(\bar x)A\gamma| = \aleph\alpha''. [The iteration of the operators O\lambda then becomes adequate for the task at hand.] The last sentence of the third paragraph of (ii) appears to be an inaccurate oversimplication. [It is clear from the rather involved proof of Theorem 2, to which these points attach, that these inaccuracies were not in the original thinking things through. There are only a few others, which are more easily spotted.]
(5) In line with (1) above and the discussion of l0(m,n) on p. 624, the condition under (i) in Theorem 4 is best possible not only for 1 \leq a \leq 3 but also for 1 \leq a \leq 4}.
Reviewer: A.H.Kruse
Classif.: * 05D10 Ramsey theory
03E05 Combinatorial set theory (logic)
04A20 Combinatorial set theory
© European Mathematical Society & FIZ Karlsruhe & Springer-Verlag | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9802266955375671, "perplexity": 1827.7268245754312}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 5, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-22/segments/1464049274119.11/warc/CC-MAIN-20160524002114-00131-ip-10-185-217-139.ec2.internal.warc.gz"} |
https://en.wikibooks.org/wiki/Principles_of_Economics/Elasticity | # Principles of Economics/Elasticity
Elasticity refers to the degree to which one value changes when another does. Supply and demand change with respect to price; investment and savings change with respect to interest rate. The name is "X elasticity of Y" where a change in X causes a change of magnitude (the elasticity * Y):
where
• ${\displaystyle P_{i}}$ is initial price
• ${\displaystyle P_{f}}$ is final price
• ${\displaystyle S_{i}}$ is initial supply
• ${\displaystyle S_{f}}$ is final supply
• ${\displaystyle D_{i}}$ is initial demand
• ${\displaystyle D_{f}}$ is final demand
• ${\displaystyle r_{i}}$ is initial interest
• ${\displaystyle r_{f}}$ is final interest
• ${\displaystyle I_{i}}$ is initial investment
• ${\displaystyle I_{f}}$ is final investment
• ${\displaystyle S_{i}}$ is initial savings
• ${\displaystyle S_{f}}$ is final savings
Price elasticity of demand
${\displaystyle ={\frac {\%changeinD}{\%changeinP}}={\frac {\frac {D_{f}-D_{i}}{(D_{f}+D_{i})/2}}{\frac {P_{f}-P_{i}}{(P_{f}+P_{i})/2}}}}$
Price elasticity of supply
${\displaystyle ={\frac {\%changeinS}{\%changeinP}}={\frac {\frac {S_{f}-S_{i}}{(S_{f}+S_{i})/2}}{\frac {P_{f}-P_{i}}{(P_{f}+P_{i})/2}}}}$
Interest elasticity of investment
${\displaystyle ={\frac {\%changeinI}{\%changeinr}}={\frac {\frac {I_{f}-I_{i}}{(I_{f}+I_{i})/2}}{\frac {r_{f}-r_{i}}{(r_{f}+r_{i})/2}}}}$
Interest elasticity of savings
${\displaystyle ={\frac {\%changeinS}{\%changeinr}}={\frac {\frac {S_{f}-S_{i}}{(S_{f}+S_{i})/2}}{\frac {r_{f}-r_{i}}{(r_{f}+r_{i})/2}}}}$
## Cross elasticities
The elasticities mentioned above refer to one object. Cross elasticities refer to the effects of something's price, interest, etc. on something else. This comes into play with substitute and complementary goods and services for the consumer | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 16, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9243857264518738, "perplexity": 3302.9953617766337}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-29/segments/1593655899931.31/warc/CC-MAIN-20200709100539-20200709130539-00525.warc.gz"} |
https://en.wikipedia.org/wiki/Ring_of_sets | # Ring of sets
Not to be confused with Ring (mathematics).
In mathematics, there are two different notions of a ring of sets, both referring to certain families of sets. In order theory, a nonempty family of sets ${\displaystyle {\mathcal {R}}}$ is called a ring (of sets) if it is closed under intersection and union. That is, the following two statements are true for all sets ${\displaystyle A}$ and ${\displaystyle B}$,
1. ${\displaystyle A,B\in {\mathcal {R}}}$ implies ${\displaystyle A\cap B\in {\mathcal {R}}}$ and
2. ${\displaystyle A,B\in {\mathcal {R}}}$ implies ${\displaystyle A\cup B\in {\mathcal {R}}.}$[1]
In measure theory, a ring of sets ${\displaystyle {\mathcal {R}}}$ is instead a nonempty family closed under unions and set-theoretic differences.[2] That is, the following two statements are true for all sets ${\displaystyle A}$ and ${\displaystyle B}$ (including when they are the same set),
1. ${\displaystyle A,B\in {\mathcal {R}}}$ implies ${\displaystyle A\setminus B\in {\mathcal {R}}}$ and
2. ${\displaystyle A,B\in {\mathcal {R}}}$ implies ${\displaystyle A\cup B\in {\mathcal {R}}.}$
This implies the empty set is in ${\displaystyle {\mathcal {R}}}$. It also implies that ${\displaystyle {\mathcal {R}}}$ is closed under symmetric difference and intersection, because of the identities
1. ${\displaystyle A\,\triangle \,B=(A\setminus B)\cup (B\setminus A)}$ and
2. ${\displaystyle A\cap B=A\setminus (A\setminus B).}$
(So a ring in the second, measure theory, sense is also a ring in the first, order theory, sense.) Together, these operations give ${\displaystyle {\mathcal {R}}}$ the structure of a boolean ring. Conversely, every family of sets closed under both symmetric difference and intersection is also closed under union and differences. This is due to the identities
1. ${\displaystyle A\cup B=(A\,\triangle \,B)\,\triangle \,(A\cap B)}$ and
2. ${\displaystyle A\setminus B=A\,\triangle \,(A\cap B).}$
## Examples
If X is any set, then the power set of X (the family of all subsets of X) forms a ring of sets in either sense.
If (X,≤) is a partially ordered set, then its upper sets (the subsets of X with the additional property that if x belongs to an upper set U and x ≤ y, then y must also belong to U) are closed under both intersections and unions. However, in general it will not be closed under differences of sets.
The open sets and closed sets of any topological space are closed under both unions and intersections.[1]
On the real line R, the family of sets consisting of the empty set and all finite unions of intervals of the form (a, b], a,b in R is a ring in the measure theory sense.
If T is any transformation defined on a space, then the sets that are mapped into themselves by T are closed under both unions and intersections.[1]
If two rings of sets are both defined on the same elements, then the sets that belong to both rings themselves form a ring of sets.[1]
## Related structures
A ring of sets (in the order-theoretic sense) forms a distributive lattice in which the intersection and union operations correspond to the lattice's meet and join operations, respectively. Conversely, every distributive lattice is isomorphic to a ring of sets; in the case of finite distributive lattices, this is Birkhoff's representation theorem and the sets may be taken as the lower sets of a partially ordered set.[1]
A field of subsets of X is a ring that contains X and is closed under relative complement. Every field, and so also every σ-algebra, is a ring of sets in the measure theory sense.
A semi-ring (of sets) is a family of sets ${\displaystyle {\mathcal {S}}}$ with the properties
1. ${\displaystyle \emptyset \in {\mathcal {S}},}$
2. ${\displaystyle A,B\in {\mathcal {S}}}$ implies ${\displaystyle A\cap B\in {\mathcal {S}},}$ and
3. ${\displaystyle A,B\in {\mathcal {S}}}$ implies ${\displaystyle A\setminus B=\bigcup _{i=1}^{n}C_{i}}$ for some disjoint ${\displaystyle C_{1},\dots ,C_{n}\in {\mathcal {S}}.}$
Clearly, every ring (in the measure theory sense) is a semi-ring.
A semi-field of subsets of X is a semi-ring that contains X.
## References
1. Birkhoff, Garrett (1937), "Rings of sets", Duke Mathematical Journal, 3 (3): 443–454, doi:10.1215/S0012-7094-37-00334-X, MR 1546000.
2. ^ De Barra, Gar (2003), Measure Theory and Integration, Horwood Publishing, p. 13, ISBN 9781904275046. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 28, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9812574982643127, "perplexity": 313.7577139476982}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-17/segments/1492917121752.57/warc/CC-MAIN-20170423031201-00318-ip-10-145-167-34.ec2.internal.warc.gz"} |
http://aas.org/archives/BAAS/v35n5/aas203/366.htm | AAS 203rd Meeting, January 2004
Session 120 Gravitational Lensing
Poster, Thursday, January 8, 2004, 9:20am-4:00pm, Hanover Hall
## [120.10] The Most Widely Separated Lensed QSO
A.R. Marble, C.D. Impey, K.A. Eriksen, L. Bai (University of Arizona), L. Miller (Oxford)
We present optical spectroscopy of the QSO pair 2QZ J1435+0008. Discovered in the 2dF QSO Survey, this pair has a redshift of z = 2.378 and an angular separation of 33\arcsec. Data taken with the MMT show that the spectra of the two QSOs are very similar over the region between Lyman-\alpha and C~IV emission, consistent with a lensing interpretation. An analysis of the Lyman-\alpha forest blueward of the emission redshift provides even stronger support for the lens hypothesis. The almost perfect correlation between the HI absorption along the two sightlines is consistent with converging sightlines that traverse the IGM on sub-galaxy scales, but is inconsistent with being binary QSOs, where the diverging sightlines would span a comoving transverse scale of ~1 Mpc. 2QZ J1435+0008 thus appears to be a gravitational lens, with by far the widest angular separation among the ~80 known examples of QSOs with multiple image formation.
Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9168018102645874, "perplexity": 9528.225882465145}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-48/segments/1386164943590/warc/CC-MAIN-20131204134903-00048-ip-10-33-133-15.ec2.internal.warc.gz"} |
https://hal.inria.fr/hal-01644518 | # Fast solution of boundary integral equations for elasticity around a crack network: a comparative study
4 ALPINES - Algorithms and parallel tools for integrated numerical simulations
LJLL - Laboratoire Jacques-Louis Lions, Institut National des Sciences Mathématiques et de leurs Interactions, Inria de Paris
Abstract : Because of the non-local nature of the integral kernels at play, the discretization of boundary integral equations leads to dense matrices, which would imply high computational complexity. Acceleration techniques, such as hierarchical matrix strategies combined with Adaptive Cross Approximation (ACA), are available in literature. Here we apply such a technique to the solution of an elastostatic problem, arising from industrial applications, posed at the surface of highly irregular cracks networks.
Type de document :
Pré-publication, Document de travail
2017
Littérature citée [15 références]
https://hal.inria.fr/hal-01644518
Contributeur : Pierre Marchand <>
Soumis le : mercredi 22 novembre 2017 - 13:37:03
Dernière modification le : mardi 15 mai 2018 - 14:50:04
### Fichier
main.pdf
Fichiers produits par l'(les) auteur(s)
### Identifiants
• HAL Id : hal-01644518, version 1
### Citation
Ibtihel Ben Gharbia, Marcella Bonazzoli, Xavier Claeys, Pierre Marchand, Pierre-Henri Tournier. Fast solution of boundary integral equations for elasticity around a crack network: a comparative study. 2017. 〈hal-01644518〉
### Métriques
Consultations de la notice
## 313
Téléchargements de fichiers | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8806018233299255, "perplexity": 10752.39930046058}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-26/segments/1529267863407.58/warc/CC-MAIN-20180620011502-20180620031502-00048.warc.gz"} |
https://physics.stackexchange.com/questions/562251/how-does-the-force-of-charge-between-particles-change-with-velocity | # How does the force of charge between particles change with velocity?
I'm sure how fast a particle moves must have some relativistic effect, or maybe also classical ones too. Suppose you fixed the positions of two charged particles. Suppose you're in a lab frame and in a paradoxical but analytically useful way, you fix the position of a particle but change its velocity towards or away from you at varying speeds.
How does the charge the lab frame measure vary due to super-relativistic effects? If the particle moves away near the speed of light, is its charge higher than it would be classically or something like that?
• Does this answer your question? How can we prove charge invariance under Lorentz Transformation? – DavidH Jun 27 '20 at 18:36
• So force is Lorentz invariant? – CheeseMongoose Jun 27 '20 at 18:52
• Your question asks two different things: How charge varies, and how force varies. – G. Smith Jun 27 '20 at 19:03
• So the force a charged particle exerts on another charged particle is in no way dependent on the charged particle's charge? Because if you say force isn't invariant yet force depends on charge which is invariant, it seems like a contradiction. – CheeseMongoose Jun 27 '20 at 19:05
• Force does depend on charge, but not only on charge. – G. Smith Jun 27 '20 at 19:08
Charge is independent of velocity. For example, the charge of a proton is $$1.6\times 10^{-19}$$ coulombs whether it is at rest or zooming around the Large Hadron Collider at 0.99999999 c. Charge is a Lorentz-invariant quantity.
$$f^\mu=qF^\mu{}_\nu u^\nu.$$
Here $$f^\mu$$ is the four-vector describing the electromagnetic force, $$F^\mu{}_\nu$$ is the four-tensor describing the electromagnetic field, and $$u^\mu$$ is the four-vector describing the velocity of the charge.
If one understands this notation, it makes clear that forces, EM fields, and velocities have straightforward Lorentz transformations, but the charge $$q$$ must be Lorentz-invariant because otherwise the right side would fail to be a four-vector like the left side is. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 6, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9342482089996338, "perplexity": 491.5075425939748}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-31/segments/1627046153521.1/warc/CC-MAIN-20210728025548-20210728055548-00060.warc.gz"} |
https://www.physicsforums.com/threads/linear-velocity-of-a-rotating-body.327899/ | # Linear velocity of a rotating body
1. Jul 30, 2009
### rugapark
1. The problem statement, all variables and given/known data
A flat rigid body is rotating with angular velocity 3 rads-1 about an axis in the
direction of the vector (i + 2 j + 3 k) and passing through the point (1, 1, 0) on
the body. Find the linear velocity of the point P = (1, 0, 1) on the body.
(You may use the result v = w x r .)
2. Relevant equations
v= w x r
3. The attempt at a solution
i have no idea where to go with this - i need to find r, but not sure how to go about using the coordinates given.
2. Jul 30, 2009
### HallsofIvy
Staff Emeritus
Do you mean 3 rads/sec (often written just "3 s-1") ?
First you need to know the radius of the circle the point is moving in. Draw a line from (1, 0, 1) to the line x= 1+ t, y= 1+ 2t, z= 3t. The plane containing (1, 0, 1) and perpendicular to i+ 2j+ 3k is (x-1)+ 2y+ 3(z-1)= 0. The line passes through that plane at (1+ t- 1)+ 2(1+ 2t)+ 3(3t-1)= 14t- 1= 0 or t= 1/14. x= 1+ 1/14, y= 1+ 2/14, z= 3/14 or (15/14, 16/14, 3/14). The distance from that point to (1, 0, 1) is
$$\sqrt{(1- 15/14)^2+ (-16/14)^2+ (1- 3/14)^2}$$
$$= \sqrt{1/196+ 256/196+ 121/196}$$
$$= 3\sqrt{42}/14$$
and that is the radius of the circle the point is moving in. (Better check my arithmetic- that looks peculiar.) From the radius you can calculate the distance corresponding to 3 radians and so the distance the particle moves in one second.
3. Aug 1, 2009
### rugapark
how did you get the x, y and z to equal those three? and where did the t's come from?
thanks for the help!
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http://mathhelpforum.com/discrete-math/33468-what-recursive-definition-1-1-n-print.html | # What is the recursive definition for 1 + (-1)^n?
• April 6th 2008, 04:56 PM
cuddll1
What is the recursive definition for 1 + (-1)^n?
What is the recursive definition for $1 + (-1)^n$?
• April 6th 2008, 05:15 PM
TheEmptySet
Quote:
Originally Posted by cuddll1
What is the recursive definition for $1 + (-1)^n$?
$a_0=0,a_1=2$
$a_{n+2}=a_n$
• April 6th 2008, 05:33 PM
Soroban
Hello, cuddll1!
Quote:
What is the recursive definition for: . $1 + (-1)^n$ ?
. . $a_{n+1} \;=\;a_n + (-1)^n\!\cdot\!2$
• April 6th 2008, 05:45 PM
cuddll1
Quote:
Originally Posted by Soroban
Hello, cuddll1!
. . $a_{n+1} \;=\;a_n + (-1)^n\!\cdot\!2$
so then using n = 1
$
a_(1+1) = a_2
= a_1 + (-1)^1 *2
= 0 + (-1)*2
= -2
$
doesn't it? but doesn't $a_2 = 2$ and not -2
I think your solution will work with (-1)^(n+1) instead of $(-1)^n$
Am I right?
Thanks for everyones help! =] | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 10, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8670579195022583, "perplexity": 6326.606398318625}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-26/segments/1466783398075.47/warc/CC-MAIN-20160624154958-00006-ip-10-164-35-72.ec2.internal.warc.gz"} |
https://www.gradesaver.com/textbooks/math/geometry/CLONE-df935a18-ac27-40be-bc9b-9bee017916c2/appendix-a-a-3-inequalities-exercises-page-551/16a | ## Elementary Geometry for College Students (7th Edition) Clone
$2\gt$-1
$-6\gt$-9 adding 8 to both sides −6+8 = 2 -9+8= -1 $2\gt$-1 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.43710294365882874, "perplexity": 7173.949009828874}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-43/segments/1570986664662.15/warc/CC-MAIN-20191016041344-20191016064844-00079.warc.gz"} |
http://mathoverflow.net/revisions/38792/list | 4 added 151 characters in body
I guess the question is somehow elementary to experts, but I'd like to put down my arguments, which appear doubtful, and see if they are correct and if corrections and improvements are possible.
The setting is as follows: $k$ is the base field of characteristic zero, $G$ a connected semi-simple $k$-group, and $Rep(G)$ the Tannakian category of finite-dimensional algebraic $k$-representations of $G$, with the canonical fiber functor in $k$-vector spaces, whose objects are called $k$-representations for short. Unless otherwise stated, reductive $k$-groups are connected.
The motivation is as follows: for $H$ semi-simple $k$-subgroup of $G$, one has the restriction functor: $Rep(G)\rightarrow Rep(H)$ sending a $k$-representation $V$ of $G$ to the restriction $V$ as a $k$-representation of $H$. What kind of irreducible $k$-representation of $G$ remains irreducible viewed in $Rep(H)$?
Recall that a reductive $k$-group is $k$-isotropic if it contains a $k$-split $k$-torus, and $k$-anisotropic if otherwise.
fact: for $H\subset G$ a semi-simple $k$-subgroup, $H$ extends to a parabolic $k$-subgroup $H\subset P\subsetneq G$ if and only if $Z(H,G)$ the centralizer of $H$ in $G$ is $k$-isotropic. (from this one also sees that if $L$ is the Levi $k$-subgroup of a $k$-parabolic $P$, then its connected center $C(L)$ is $k$-isotropic.)
claim: let $H$ be a semi-simple $k$-subgroup of $G$ as above, such that $Z(H,G)$ is $k$-anisotropic, then for any irreducible $k$-representation $(\rho,V)$ of $G$, its restriction to $H$ is irreducible as an algebraic $k$-representation of $H$. Conversely, if the restriction functor $Rep(G)\rightarrow Rep(H)$ respects irreducibility, with $H\subset G$ a semi-simple $k$-subgroup, then $Z(H,G)$ is $k$-anisotropic.
Sketch of the proof: To prove the first part, assume that for some irreducible $(\rho,V)$, the restriction to $H$ is not irreducible. Then in $Rep(H)$ one has a non-trivial splitting $V=V_1\oplus V_2$. Define $F_0(V)=V$, $F_1=V_1$, $F_2=0$ etc, one gets a non-trivial decreasing filtration on $V$. $V$ generates a full Tannakian subcategory, which is of the form $Rep(G')$, equipped with the non-trivial filtration generated by $F(V)$. By Tannaka duality, $Rep(G')\rightarrow Rep(G)$ corresponds to an epimorphism $G\rightarrow G'$. $G'$ is thus semi-simple. The non-trivial filtration on $Rep(G')$ corresponds to a cocharacter defined over $k$, which is equivalently characterized by $k$-parabolic $P'$ of $G'$, and $P'$ lifts to a $k$-parabolic $P$ of $G$. One checks easily that $P$ contains $H$, because $H$ preserves the filtration generated by $F(V)$. This shows that $Z(H,G)$ is $k$-isotropic.
Conversely, when $Z(H,G)$ is $k$-isotropic, $H$ extends to a non-trivial $k$-parabolic $H\subset P\subsetneq G$. This gives a filtration on $Rep(G)$, preserved by $P$ and $H$. In particular, there exists at least one irreducible $k$-representation $(\rho,V)$ of $G$ on which $F(V)$ is non-trivial, and then the restriction of $\rho$ to $H$ splits non-trivially.
Here I use the notion of filtration on $Rep(G)$, which means for each $V\in Rep(G)$ one has a finite separated exhaustive decreasing filtration $F(V)$, moving functorially: it respects the tensor products and direct sums in the filtered sense, and is strict with respect to all exact sequences in $Rep(G)$. To see a filtration on $Rep(G')$ extends to a filtration on $Rep(G)$ for an epimorphism $G\rightarrow G'$ as above, it suffices to transfer to the Lie algebra side: $LieG=LieG'\oplus Lie G''$ for some semi-simple $k$-subgroup $G''$ of $G$, then use the fact that $Rep(LieG)$ equals the "exterior tensor product" of $Rep(LieG')$ with $Rep(LieG'')$, and pass equivalently to the $k$-group side, as $k$ is of characteristic zero. In this way the filtration on $Rep(G')$, together with the trivial filtration on $Rep(G'')$, gives a filtration on $Rep(G)$ by tensorial construction.
I would like to know if the above arguments makes sense. If it is, is there any other elementary proof, essentially different (modulo the Tannakian duality). Moreover, what if one allows reductive $k$-subgroup? Does that imply the claim that over $\mathbb{R}$, if one takes a pair of compact groups, say $SO_3\subset SO_4$, every irreducible representation of $SO_4$ remains irreducible when restricted to $SO_3$? and does it have anything to do with the branching rule? I would be grateful if further references, like expository articles, are mentioned concerning branching rules for reductive $k$-groups, even in the case of non-algebraically base field (I guess one might do something from the algebraically closed case through Galois descent, but I'm quite lost when doing this for reductive $k$-groups.)
Thanks a lot.
3 Spelling corrected
# whenWhen does an irreducible representation remains ireducible after restriction to a semi-simple subgroup?
I guess the question is somehow elementary to experts, but I'd like to put down my arguments, which appear doubtful, and see if they are correct and if corrections and improvements are possible.
The setting is as follows: $k$ is the base field of characteristic zero, $G$ a connected semi-simple $k$-group, and $Rep(G)$ the Tannakian category of finite-dimensional algebraic $k$-representations of $G$, with the canonical fiber functor in $k$-vecor k$-vector spaces, whose objects are called$k$-representations for short. Unless otherwise stated, reductive$k$-groups are connected. The motivation is as follows: for$H$semi-simple$k$-subgroup of$G$, one has the restriction functor:$Rep(G)\rightarrow Rep(H)$sending a$k$-representation$V$of$G$to the restriction$V$as a$k$-representation of$H$. What kind of irreducible$k$-representation of$G$remains irreducible viewed in$Rep(H)$? Recall that a reductive$k$-group is$k$-isotropic if it contains a$k$-split$k$-torus, and$k$-anisotropic if otherwise. fact: for$H\subset G$a semi-simple$k$-subgroup,$H$extends to a parablic parabolic$k$-subgroup$H\subset P\subsetneq G$if and only if$Z(H,G)$the centralizer of$H$in$G$is$k$-isotropic. (from this one also sees that if$L$is the Levi$k$-subgroup of a$k$-parabolic$P$, then its connected center$C(L)$is$k$-isotropic.) claim: let$H$be a semi-simple$k$-subgroup of$G$as above, such that$Z(H,G)$is$k$-anisotropic, then for any irreducible$k$-representation$(\rho,V)$of$G$, its restriction to$H$is irreducible as an algebraic$k$-represnetation k$-representation of $H$. Conversely, if the retriction restriction functor $Rep(G)\rightarrow Rep(H)$ respects irreducibility, with $H\subset G$ a semi-simple $k$-subgroup, then $Z(H,G)$ is $k$-anisotropic.
Sketch of the proof: To prove the first part, assume that for some irreducible $(\rho,V)$, the restriction to $H$ is not irreducible. Then in $Rep(H)$ one has a non-trivial splitting $V=V_1\oplus V_2$. Define $F_0(V)=V$, $F_1=V_1$, $F_2=0$ etc, one gets a non-trivial decreasing filtration on $V$. $V$ generates a full Tannakian subcategory, which is of the form $Rep(G')$, equipped with the non-trivial filtration generated by $F(V)$. By Tannaka duality, $Rep(G')\rightarrow Rep(G)$ corresponds to an epimorphism $G\rightarrow G'$. $G'$ is thus semi-simple. The non-trivial filtration on $Rep(G')$ corresponds to a cocharacter defined over $k$, which is equivalently characterized by $k$-parabolic $P'$ of $G'$, and $P'$ lifts to a $k$-parabolic $P$ of $G$. One checks easily that $P$ contains $H$, because $H$ preserves the filtration generated by $F(V)$. This shows that $Z(H,G)$ is $k$-isotropic.
Conversely, when $Z(H,G)$ is $k$-isotropic, $H$ extends to a non-trivial $k$-parabolic $H\subset P\subsetneq G$. This gives a filtration on $Rep(G)$, preserved by $P$ and $H$. In particular, there exists at least one irreducible $k$-represnetation k$-representation$(\rho,V)$of$G$on which$F(V)$is non-trivial, and then the restriction of$\rho$to$H$splits non-trivially. Here I use the notion of filtration on$Rep(G)$, which means for each$V\in Rep(G)$one has a finite separated exhaustive decreasing filtration$F(V)$, moving functorially: it respects the tensor products and direc direct sums in the filtred filtered sense, and is strict with respect to all exact sequences in$Rep(G)$. To see a filtration on$Rep(G')$extends to a filtration on$Rep(G)$for an epimorphism$G\rightarrow G'$as above, it suffices to transfer to the Lie algebra side:$LieG=LieG'\oplus Lie G''$for some semi-simple$k$-subgroup$G''$of$G$, then use the fact that$Rep(LieG)$equals the "exterior tensor product" of$Rep(LieG')$with$Rep(LieG'')$, and pass equivalently to the$k$-group side, as$k$is of characteristic zero. I would like to know if the above arguments makes sense. If it is, is there any other elementary proof, essentially different (modulo the Tannakian duality). Moreover, what if one allows reductive$k$-subgroup? Does that imply the claim that over$\mathbb{R}$, if one takes a pair of compact groups, say$SO_3\subset SO_4$, every irreducible represenation representation of$SO_4$remains irreducible when restricted to$SO_3$? and does it have anything to do with the branching rule? I would be grateful if further references, like expository articles, are mentioned concerning branching rules for reductive$k$-groups, even in the case of non-algebraically base field (I guess one might do something from the algebraically closed case through Galois descent, but I'm quite lost when doing this for reductive$k$-groups.) Thanks a lot. 2 added 14 characters in body I guess the question is somehow elementary to experts, but I'd like to put down my arguments, which appear doubtful, and see if they are correct and if corrections and improvements are possible. The setting is as follows:$k$is the base field of characteristic zero,$G$a connected semi-simple$k$-group, and$Rep(G)$the Tannakian category of finite-dimensional algebraic$k$-representations of$G$, with the canonical fiber functor in$k$-vecor spaces, whose objects are called$k$-representations for short. Unless otherwise stated, reductive$k$-groups are connected. The motivation is as follows: for$H$semi-simple$k$-subgroup of$G$, one has the restriction functor:$Rep(G)\rightarrow Rep(H)$sending a$k$-representation$V$of$G$to the restriction$V$as a$k$-representation of$H$. What kind of irreducible$k$-representation of$G$remains irreducible viewed in$Rep(H)$? Recall that a reductive$k$-group is$k$-isotropic if it contains a$k$-split$k$-torus, and$k$-anisotropic if otherwise. fact: for$H\subset G$a semi-simple$k$-subgroup,$H$extends to a parablic$k$-subgroup$H\subset P\subsetneq G$if and only if$Z(H,G)$the centralizer of$H$in$G$is$k$-isotropic. (from this one also sees that if$L$is the Levi$k$-subgroup of a$k$-parabolic$P$, then its connected center$C(L)$is$k$-isotropic.) claim: let$H$be a semi-simple$k$-subgroup of$G$as above, such that$Z(H,G)$is$k$-anisotropic, then for any irreducible$k$-representation$(\rho,V)$of$G$, its restriction to$H$is irreducible as an algebraic$k$-represnetation of$H$. Conversely, if the retriction functor$Rep(G)\rightarrow Rep(H)$respects irreducibility, with$H\subset G$a semi-simple$k$-subgroup, then$Z(H,G)$is$k$-anisotropic. Sketch of the proof: To prove the first part, assume that for some irreducible$(\rho,V)$, the restriction to$H$is not irreducible. Then in$Rep(H)$one has a non-trivial splitting$V=V_1\oplus V_2$. Define$F_0(V)=V$,$F_1=V_1$,$F_2=0$etc, one gets a non-trivial decreasing filtration on$V$.$V$generates a full Tannakian subcategory, which is of the form$Rep(G')$, equipped with the non-trivial filtration generated by$F(V)$. By Tannaka duality,$Rep(G')\rightarrow Rep(G)$corresponds to an epimorphism$G\rightarrow G'$.$G'$is thus semi-simple. The non-trivial filtration on$Rep(G')$corresponds to a cocharacter defined over$k$, which is equivalently characterized by$k$-parabolic$P'$of$G'$, and$P'$lifts to a$k$-parabolic$P$of$G$. One checks easily that$P$contains$H$, because$H$preserves the filtration generated by$F(V)$. This shows that$Z(H,G)$is$k$-isotropic. Conversely, when$Z(H,G)$is$k$-isotropic,$H$extends to a non-trivial$k$-parabolic$H\subset P\subsetneq G$. This gives a filtration on$Rep(G)$, preserved by$P$and$H$. In particular, there exists at least one irreducible$k$-represnetation$(\rho,V)$of$G$on which$F(V)$is non-trivial, and then the restriction of$\rho$to$H$splits non-trivially. Here I use the notion of filtration on$Rep(G)$, which means for each$V\in Rep(G)$one has a finite separated exhaustive decreasing filtration$F(V)$, moving functorially: it respects the tensor products and direc sums in the filtred sense, and is strict with respect to all exact sequences in$Rep(G)$. To see a filtration on$Rep(G')$extends to a filtration on$Rep(G)$for an epimorphism$G\rightarrow G'$as above, it suffices to transfer to the Lie algebra side:$LieG=LieG'\oplus Lie G''$for some semi-simple$k$-subgroup$G''$of$G$, then use the fact that$Rep(LieG)$equals the "exterior tensor product" of$Rep(LieG')$with$Rep(LieG'')$, and pass equivalently to the$k$-group side, as$k$is of characteristic zero. I would like to know if the above arguments makes sense. If it is, is there any other elementary proof, essentially different (modulo the Tannakian duality). Moreover, what if one allows reductive$k$-subgroup? Does that imply the claim that over$\mathbb{R}$, if one takes a pair of compact groups, say$SO_3\subset SO_4$, every irreducible represenation of$SO_4$remains irreducible when restricted to$SO_3$? and does it have anything to do with the branching rule? I would be grateful if further references, like expository articles, are mentioned concerning branching rules for reductive$k$-groups, even in the case of non-algebraically base field (I guess one might do something from the algebraically closed case through Galois descent, but I'm quite lost when doing this for reductive$k\$-groups.)
Thanks a lot.
1 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9764245748519897, "perplexity": 270.3022795352607}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368705948348/warc/CC-MAIN-20130516120548-00006-ip-10-60-113-184.ec2.internal.warc.gz"} |
http://www.actuarialoutpost.com/actuarial_discussion_forum/showthread.php?s=80ea725b6a537fc8eedd431bc85f2775&mode=hybrid&t=338195 | Actuarial Outpost LTAM prerequisites
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#1
02-12-2019, 04:42 PM
trent216904 SOA Join Date: Jun 2018 College: IUSB Posts: 10
LTAM prerequisites
On the LTAM page of SOA's website, it states, "A thorough knowledge of calculus, probability (as covered in Exam P), mathematical statistics (as covered in VEE Mathematical Statistics) and interest theory (as covered in Exam FM) is assumed." I've already passed P and FM (and am taking IFM next month), but I haven't taken the MS VEE yet. I was planning on taking LTAM in October, and I'm not sure I can fit in the MS course before then - I'm starting work in June, so I don't want to pay for VEE course now since if I wait a few months, my employer will pay for it. However, if I start the VEE in June, I don't think that will give me enough time to study for LTAM.
Anyways, all that to ask: will I be ok studying for LTAM without the MS VEE, or is it something that would be really beneficial to have under my belt before LTAM?
#2
02-12-2019, 04:50 PM
Abraham Weishaus Member SOA AAA Join Date: Oct 2001 Posts: 7,237
The only use of statistics is in the part of the course discussing mortality rate estimation. You can probably get by without it, since the statistical methods used to derive the formulas (like MLE and its variance) are not directly tested on.
#3
02-12-2019, 05:09 PM
DyalDragon Member SOA Join Date: Apr 2009 Location: Here Studying for the hell of it... College: AASU Favorite beer: This one... Posts: 32,548
Quote:
Originally Posted by trent216904 On the LTAM page of SOA's website, it states, "A thorough knowledge of calculus, probability (as covered in Exam P), mathematical statistics (as covered in VEE Mathematical Statistics) and interest theory (as covered in Exam FM) is assumed." I've already passed P and FM (and am taking IFM next month), but I haven't taken the MS VEE yet. I was planning on taking LTAM in October, and I'm not sure I can fit in the MS course before then - I'm starting work in June, so I don't want to pay for VEE course now since if I wait a few months, my employer will pay for it. However, if I start the VEE in June, I don't think that will give me enough time to study for LTAM. Anyways, all that to ask: will I be ok studying for LTAM without the MS VEE, or is it something that would be really beneficial to have under my belt before LTAM?
In my experience, any study manual worth the paper it's printed on (or online study lecture course) will include review of the necessary basics.
If you prefer to use the recommended textbooks from the syllabus you may need to track down some online resources for any topics you might need a refresher on.
__________________
P FM MFE MLC C Predictive Analytics
VEE FAP FAP FAP FAP FAP FAP FAP FAP APC
Last edited by DyalDragon; 02-12-2019 at 05:13 PM..
#4
02-25-2019, 03:28 PM
gaudettj Member SOA Join Date: Nov 2013 Location: Canada Studying for FAP / C Favorite beer: All of the Above Posts: 246
If you had the skills to pass P and FM, you should have the knowledge required to understand the material. Anything new will be developed as you progress through the course, and from what I remember, it had very little overlap with mathematical statistics other than the stuff already covered in the first two exams.
__________________
________________________
VEE's P FM IFM SRM LTAM FAP PA STAM APC
#5
03-02-2019, 11:24 AM
NchooseK Member SOA Join Date: Nov 2012 Location: Philly area Studying for PA, LTAM, FA (FAP) College: Swarthmore College (BA Mathematics), Villanova University (MS Applied Stat) Favorite beer: I don't drink beer, but I love the Dos Equis commercials. Posts: 353
Pre-reqs and potentially familiar topics. Everything is covered in a good manual, such as CA.
Calculus:
• The integral ${\normal \int} \, te^{-kt} \, \mathrm{d}t$
• Finite and infinite geometric sums
• Basic "u" substitution and appropriately adjusting limits of integration.
• VERY basic differentiation.
• Limits only as they apply to improper integrals.
Math:
• Rules of logs and exponents.
• Rules of inequalities; flipping sign when multiplying a negative.
• Recursion.
• Counting--I'm not kidding. Use your fingers if it helps!
• Matrix multiplication.
• Linear Interpolation.
• Cubic Splines.
Probability/Statistics:
• Expectation, Variance and Covariance operators (including linear combinations)
• Compute Variance from first two moments
• Independence, Mutual Exclusivity.
• Normal Approximation
• Double Expectation and Conditional Variance
• Bernoulli Shortcut for Variance
• Distribution and density/mass functions.
• Be prepared to answer a (short response) question in the context of the Central Limit Theorem or the Law of Large Numbers. Cursory understanding fine.
• Sums and products of Standard Normal RVs. Moments. Independence.
• Relationship and conversion between Normal and Log Normal. Means and Variances.
• Empirical Distr, Histogram (function), Ogive
• Exponential Distr. Recognize its form and know its mean.
• Confidence Intervals.
• Logit Function.
• Compute Correlation $\rho$ from Covariance and Variances/Standard Deviations.
Financial Math / Other:
• Though the section on spot and forward rates has been removed, know these since a few problems require it.
• Interest rates, compounding, 1/m-thly payments, annualization, discount rate,
__________________
Exams: P | FM | C | MFE | LTAM | SRM Credit | PA
VEE: Statistics | Finance | Economics
FAP: 1 | 2 | 3 | 4 | IA | 6 | 7 | FA
Conferences: APC
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https://www.aimsciences.org/article/doi/10.3934/era.2015.22.12 | American Institute of Mathematical Sciences
January 2015, 22: 12-19. doi: 10.3934/era.2015.22.12
Smoothing 3-dimensional polyhedral spaces
1 Steklov Institute, St. Petersburg, Russian Federation 2 Institut für Mathematik, Friedrich-Schiller-Universität Jena, Germany 3 Mathematics Department, Pennsylvania State University, United States 4 National Research University, Higher School of Economics, Moscow, Russian Federation
Received November 2014 Published June 2015
We show that 3-dimensional polyhedral manifolds with nonnegative curvature in the sense of Alexandrov can be approximated by nonnegatively curved 3-dimensional Riemannian manifolds.
Citation: Nina Lebedeva, Vladimir Matveev, Anton Petrunin, Vsevolod Shevchishin. Smoothing 3-dimensional polyhedral spaces. Electronic Research Announcements, 2015, 22: 12-19. doi: 10.3934/era.2015.22.12
References:
[1] C. Böhm and B. Wilking, Manifolds with positive curvature operators are space forms,, \emph{Ann. of Math. (2)}, 167 (2008), 1079. doi: 10.4007/annals.2008.167.1079. Google Scholar [2] B.-L. Chen, G. Xu and Z. Zhang, Local pinching estimates in 3-dim Ricci flow,, \emph{Math. Res. Lett.}, 20 (2013), 845. doi: 10.4310/MRL.2013.v20.n5.a3. Google Scholar [3] R. S. Hamilton, A compactness property for solutions of the Ricci flow,, \emph{Amer. J. Math.}, 117 (1995), 545. doi: 10.2307/2375080. Google Scholar [4] V. Kapovitch, Regularity of limits of noncollapsing sequences of manifolds,, \emph{Geom. Funct. Anal.}, 12 (2002), 121. doi: 10.1007/s00039-002-8240-1. Google Scholar [5] A. Petrunin, Polyhedral approximations of Riemannian manifolds,, \emph{Turkish J. Math.}, 27 (2003), 173. Google Scholar [6] T. Richard, Lower bounds on Ricci flow invariant curvatures and geometric applications,, \emph{J. Reine Angew. Math.}, 703 (2015), 27. doi: 10.1515/crelle-2013-0042. Google Scholar [7] M. Simon, Ricci flow of almost non-negatively curved three manifolds,, \emph{J. Reine Angew. Math.}, 630 (2009), 177. doi: 10.1515/CRELLE.2009.038. Google Scholar [8] M. Simon, Ricci flow of non-collapsed three manifolds whose Ricci curvature is bounded from below,, \emph{J. Reine Angew. Math.}, 662 (2012), 59. doi: 10.1515/CRELLE.2011.088. Google Scholar [9] W. Spindeler, $S^1$-Actions on 4-Manifolds and Fixed Point Homogeneous Manifolds of Nonnegative Curvature,, Ph.D. Thesis, (2014). Google Scholar
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References:
[1] C. Böhm and B. Wilking, Manifolds with positive curvature operators are space forms,, \emph{Ann. of Math. (2)}, 167 (2008), 1079. doi: 10.4007/annals.2008.167.1079. Google Scholar [2] B.-L. Chen, G. Xu and Z. Zhang, Local pinching estimates in 3-dim Ricci flow,, \emph{Math. Res. Lett.}, 20 (2013), 845. doi: 10.4310/MRL.2013.v20.n5.a3. Google Scholar [3] R. S. Hamilton, A compactness property for solutions of the Ricci flow,, \emph{Amer. J. Math.}, 117 (1995), 545. doi: 10.2307/2375080. Google Scholar [4] V. Kapovitch, Regularity of limits of noncollapsing sequences of manifolds,, \emph{Geom. Funct. Anal.}, 12 (2002), 121. doi: 10.1007/s00039-002-8240-1. Google Scholar [5] A. Petrunin, Polyhedral approximations of Riemannian manifolds,, \emph{Turkish J. Math.}, 27 (2003), 173. Google Scholar [6] T. Richard, Lower bounds on Ricci flow invariant curvatures and geometric applications,, \emph{J. Reine Angew. Math.}, 703 (2015), 27. doi: 10.1515/crelle-2013-0042. Google Scholar [7] M. Simon, Ricci flow of almost non-negatively curved three manifolds,, \emph{J. Reine Angew. Math.}, 630 (2009), 177. doi: 10.1515/CRELLE.2009.038. Google Scholar [8] M. Simon, Ricci flow of non-collapsed three manifolds whose Ricci curvature is bounded from below,, \emph{J. Reine Angew. Math.}, 662 (2012), 59. doi: 10.1515/CRELLE.2011.088. Google Scholar [9] W. Spindeler, $S^1$-Actions on 4-Manifolds and Fixed Point Homogeneous Manifolds of Nonnegative Curvature,, Ph.D. Thesis, (2014). Google Scholar
[1] Yafeng Li, Guo Sun, Yiju Wang. A smoothing Broyden-like method for polyhedral cone constrained eigenvalue problem. Numerical Algebra, Control & Optimization, 2011, 1 (3) : 529-537. doi: 10.3934/naco.2011.1.529 [2] Alberto Farina, Enrico Valdinoci. A pointwise gradient bound for elliptic equations on compact manifolds with nonnegative Ricci curvature. Discrete & Continuous Dynamical Systems - A, 2011, 30 (4) : 1139-1144. doi: 10.3934/dcds.2011.30.1139 [3] Xumin Jiang. Isometric embedding with nonnegative Gauss curvature under the graph setting. Discrete & Continuous Dynamical Systems - A, 2019, 39 (6) : 3463-3477. doi: 10.3934/dcds.2019143 [4] Diego Castellaneta, Alberto Farina, Enrico Valdinoci. A pointwise gradient estimate for solutions of singular and degenerate pde's in possibly unbounded domains with nonnegative mean curvature. Communications on Pure & Applied Analysis, 2012, 11 (5) : 1983-2003. doi: 10.3934/cpaa.2012.11.1983 [5] Joel Spruck, Ling Xiao. Convex spacelike hypersurfaces of constant curvature in de Sitter space. Discrete & Continuous Dynamical Systems - B, 2012, 17 (6) : 2225-2242. doi: 10.3934/dcdsb.2012.17.2225 [6] Yoshikazu Giga, Yukihiro Seki, Noriaki Umeda. On decay rate of quenching profile at space infinity for axisymmetric mean curvature flow. Discrete & Continuous Dynamical Systems - A, 2011, 29 (4) : 1463-1470. doi: 10.3934/dcds.2011.29.1463 [7] Matthias Bergner, Lars Schäfer. Time-like surfaces of prescribed anisotropic mean curvature in Minkowski space. Conference Publications, 2011, 2011 (Special) : 155-162. doi: 10.3934/proc.2011.2011.155 [8] Chiara Corsato, Franco Obersnel, Pierpaolo Omari, Sabrina Rivetti. On the lower and upper solution method for the prescribed mean curvature equation in Minkowski space. Conference Publications, 2013, 2013 (special) : 159-169. doi: 10.3934/proc.2013.2013.159 [9] Elias M. Guio, Ricardo Sa Earp. Existence and non-existence for a mean curvature equation in hyperbolic space. Communications on Pure & Applied Analysis, 2005, 4 (3) : 549-568. doi: 10.3934/cpaa.2005.4.549 [10] Hongjie Ju, Jian Lu, Huaiyu Jian. Translating solutions to mean curvature flow with a forcing term in Minkowski space. Communications on Pure & Applied Analysis, 2010, 9 (4) : 963-973. doi: 10.3934/cpaa.2010.9.963 [11] Qinian Jin, YanYan Li. Starshaped compact hypersurfaces with prescribed $k$-th mean curvature in hyperbolic space. Discrete & Continuous Dynamical Systems - A, 2006, 15 (2) : 367-377. doi: 10.3934/dcds.2006.15.367 [12] Nicolas Bedaride. Entropy of polyhedral billiard. Discrete & Continuous Dynamical Systems - A, 2007, 19 (1) : 89-102. doi: 10.3934/dcds.2007.19.89 [13] Oleksandr Misiats, Nung Kwan Yip. Convergence of space-time discrete threshold dynamics to anisotropic motion by mean curvature. Discrete & Continuous Dynamical Systems - A, 2016, 36 (11) : 6379-6411. doi: 10.3934/dcds.2016076 [14] Ruyun Ma, Man Xu. Connected components of positive solutions for a Dirichlet problem involving the mean curvature operator in Minkowski space. Discrete & Continuous Dynamical Systems - B, 2019, 24 (6) : 2701-2718. doi: 10.3934/dcdsb.2018271 [15] Ye Tian, Qingwei Jin, Zhibin Deng. Quadratic optimization over a polyhedral cone. Journal of Industrial & Management Optimization, 2016, 12 (1) : 269-283. doi: 10.3934/jimo.2016.12.269 [16] Janusz Mierczyński. Averaging in random systems of nonnegative matrices. Conference Publications, 2015, 2015 (special) : 835-840. doi: 10.3934/proc.2015.0835 [17] Chaoqian Li, Yaqiang Wang, Jieyi Yi, Yaotang Li. Bounds for the spectral radius of nonnegative tensors. Journal of Industrial & Management Optimization, 2016, 12 (3) : 975-990. doi: 10.3934/jimo.2016.12.975 [18] Przemysław Górka. Quasi-static evolution of polyhedral crystals. Discrete & Continuous Dynamical Systems - B, 2008, 9 (2) : 309-320. doi: 10.3934/dcdsb.2008.9.309 [19] Gurkan Ozturk, Mehmet Tahir Ciftci. Clustering based polyhedral conic functions algorithm in classification. Journal of Industrial & Management Optimization, 2015, 11 (3) : 921-932. doi: 10.3934/jimo.2015.11.921 [20] Chinmay Kumar Giri. Index-proper nonnegative splittings of matrices. Numerical Algebra, Control & Optimization, 2016, 6 (2) : 103-113. doi: 10.3934/naco.2016002
2018 Impact Factor: 0.263 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7469823360443115, "perplexity": 6443.2046277476775}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-35/segments/1566027313996.39/warc/CC-MAIN-20190818185421-20190818211421-00236.warc.gz"} |
https://iwaponline.com/wst/article-abstract/27/5-6/449/3874/Thermic-Sludge-Treatment?redirectedFrom=PDF | Chemical pretreatment changes the composition of waste water by reducing the paniculate organic matter.
A lower biological sludge production from the sewage facilitates nitrification.
The denitrification capacity of the sewage is decreased, but the fraction of low molecular substances is not influenced by the chemical treatment.
To increase the denitrification capacity, the organic matter removed can be hydrolised into a readily degradable form and used as an electron donor. In Tampere waste water plant the sludge is hydrolysed at 150° C in a low pH environment.
The carbon source was increasing the capacity of the anoxic zone.
The sludge dewatering characteristics were improved.
The sludge is divided into two fractions, one with paniculate organic matter, the other containing a solution of organic and inorganic substances. The heavy metals can be separated and the precipitant recovered and recycled.
This content is only available as a PDF. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8382325768470764, "perplexity": 5964.471412049826}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-43/segments/1634323585246.50/warc/CC-MAIN-20211019074128-20211019104128-00082.warc.gz"} |
https://www.freemathhelp.com/trig-double-angles.html | # Solve Trig Problems With Double- or Half-Angles
The double and half angle formulas can be used to find the values of unknown trig functions. For example, you might not know the sine of 15 degrees, but by using the half angle formula for sine, you can figure it out based on the commonly known value of sin(30) = 1/2.
They are also useful for certain integration problems where a double or half angle formula may make things much simpler to solve.
## Double Angle Formulas:
You'll notice that there are several listings for the double angle for cosine. That's because you can substitute for either of the squared terms using the basic trig identity $$\sin^2+\cos^2=1$$.
## Half Angle Formulas:
These are a little trickier because of the plus or minus. It's not that you can use BOTH, but you have to figure out the sign on your own. For example, the sine of 30 degrees is positive, as is the sine of 15. However, if you were to use 200, you'd find that the sine of 200 degrees is negative, while the sine of 100 is positive. Just remember to look at a graph and figure out the sines and you'll be fine. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9673099517822266, "perplexity": 201.4137040794858}, "config": {"markdown_headings": true, "markdown_code": false, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-30/segments/1500549423842.79/warc/CC-MAIN-20170722022441-20170722042441-00638.warc.gz"} |
https://figshare.com/articles/Expression_of_RavK_causes_cytotoxicity_in_both_yeast_and_mammalian_cells_and_reduces_the_F-actin_content_in_mammalian_cells_/4592743/1 | ## Expression of RavK causes cytotoxicity in both yeast and mammalian cells and reduces the F-actin content in mammalian cells.
2017-01-27T04:30:02Z (GMT) by
<p><b>A</b>. A schematic diagram of RavK. The blue box highlighted the position and the sequence of the predicted HE<sub>XX</sub>H motif. <b>B</b>. Expression of RavK induces yeast growth arrest in an H<sub>95</sub>E<sub>XX</sub>H<sub>99</sub>-dependent manner. Yeast strains expressing RavK or the indicated mutants under the control of the galactose-inducible promoter were serial-diluted and spotted onto plates containing glucose or galactose, respectively. Plates were incubated at 30°C for 48 h before image acquisition. <b>C</b>. Expression of RavK and the indicated mutants in yeast. Yeast strains grown in glucose medium to saturation were washed with water 5 times and split equally to 2 halves. One half was frozen immediately (sample 1), the other half was induced in galactose medium for 8 h (sample 2). Total proteins of all samples were resolved by SDS/PAGE and probed by immunoblotting with a RavK-specific antibody. The 3-phosphoglycerate kinase (PGK) was used as a loading control. <b>D</b>. RavK reduces F-actin content in COS-1 cells. COS-1 cells transfected by the indicated plasmids for 24 h were fixed and subjected to Texas-red-conjugated phalloidin staining. Images from one representative were shown and similar results were obtained in at least three experiments. Bar, 20 μm. E. Integrated pixel density of phalloidin staining in cells expressing indicated proteins plotted as average F-actin intensity per cell. N>60 per condition; error bars represent standard error of the mean (SEM); A.U., arbitrary units; ****, <i>p</i><0.0001. F. The spread cell area of cells expressing indicated proteins plotted as average area per cell. N>60 per condition; N.S., not significant; *, <i>p</i><0.05.</p> | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8533875346183777, "perplexity": 19490.670780296212}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-51/segments/1544376831334.97/warc/CC-MAIN-20181219045716-20181219071716-00636.warc.gz"} |
http://inventtolearn.com/3n/ | # The 3N problem
SCENARIO
You and your noted mathematician colleagues convene in (virtual) Geneva to present brilliant theories pertaining to one of the world’s great mysteries, the elusive 3n Problem.
BACKGROUND
The 3N problem offers a fantastic world of exploration for learners of all ages. (I have done this with kids as young as the third grade.)
The problem is known by several other names, including: Ulam’s problem, the Hailstone problem, the Syracuse problem, Kakutani’s problem, Hasse’s algorithm, Thwaite’s Conjecture 3X+1 Mapping and the Collatz problem.
The 3N problem has a simple set of rules. Put a positive integer (1, 2, 3, etc…) in a “machine.” If the number is even, cut in half – if it is odd, multiply it by 3 and add 1. Then put the resulting value back through the machine. For example, 5 becomes 16, 16 becomes 8, becomes 4, 4 becomes 2, 2 becomes 1, and 1 becomes 4. Mathematicians have observed that any number placed into the machine will eventually be reduced to a repeating pattern of 4…2…1…
This observation has yet to be proven since only a few billion integers have been tested. The 4…2…1… pattern therefore remains a conjecture.
The computer will serve as your lab assistant – smart enough to work hard without sleep, food or pay, but not so smart that it does the thinking for you. It will collect data and represent it in three different ways for you. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8445913195610046, "perplexity": 1214.1105996957717}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-26/segments/1498128320070.48/warc/CC-MAIN-20170623151757-20170623171757-00198.warc.gz"} |
https://www.studyadda.com/ncert-solution/ratio-and-propotion_q22/545/45372 | • # question_answer 22) Ekta earns Rs. 1500 in 10 days. How much will she earn in 30 days?
Here, the number of days is known and money earns is unknown. Given, Ekta earns in 10 days = Rs. 1500 $\therefore$ Ekta earns in 1 day = Rs. $\frac{1500}{10}=$ Rs. 150 $\therefore$ Ekta earns in 30 days = Rs. $150\times 30=$Rs. 4500 Hence, Ekta earns Rs. 4500 in 30 days. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8445809483528137, "perplexity": 8026.375504084894}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-43/segments/1570987822458.91/warc/CC-MAIN-20191022155241-20191022182741-00494.warc.gz"} |
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Showing results 1 to 25 of 1000 Search took 0.11 seconds. Search: Posts Made By: Wacky
Forum: Soap Box 2012-03-05, 14:52 Replies: 94 Views: 5,166 Posted By Wacky The problem with "a-la-carte" pricing is that... The problem with "a-la-carte" pricing is that your idea of an acceptable price point is far too low to support the "fringe" audiences of each of those channels. Although you are willing to pay for...
Forum: Puzzles 2012-03-04, 20:53 Replies: 20 Views: 2,041 Posted By Wacky What is "snow"? (Last... What is "snow"? (Last year, we were even asking "What is rain?")
Forum: Soap Box 2011-12-22, 20:44 Replies: 137 Views: 7,352 Posted By Wacky Bob, I think that your last post exposes the... Bob, I think that your last post exposes the fundamental cause of this conflict in viewpoints. AFAICT, you view questions in this forum as if they were being ask by someone who is in the...
Forum: Linux 2011-12-12, 15:52 Replies: 20 Views: 3,170 Posted By Wacky It would, perhaps be better if you would actually... It would, perhaps be better if you would actually provide the details of your observations and not just your conclusions. For example, what CPU are you using? Are the hard drives equal in speed and...
Forum: Soap Box 2011-10-04, 13:57 Replies: 1,649 Views: 87,804 Posted By Wacky Brian, Although I support "the advocacy of... Brian, Although I support "the advocacy of legal recognition ...", I do not wish to be such an advocate, nor do I wish to advocate for the opposition. I will point out that you are making an...
Forum: Soap Box 2011-10-03, 22:57 Replies: 1,649 Views: 87,804 Posted By Wacky Because you are not stating, correctly, just what... Because you are not stating, correctly, just what the NIS (or is it now ICE) is doing.
Forum: Soap Box 2011-10-03, 22:51 Replies: 1,649 Views: 87,804 Posted By Wacky Although I believe that marriage is a religious... Although I believe that marriage is a religious sacrament limited to the joining of a man and a woman, I support the recognition of relationships in other communities which represent "permanent"...
Forum: Soap Box 2011-09-27, 13:46 Replies: 1,649 Views: 87,804 Posted By Wacky The NIS is tasked with detecting fraudulent... The NIS is tasked with detecting fraudulent marriages. Rather than REQUIRING "love", the assessment of that, along with other aspects of the relationship, is utilized as an indicator of the nature of...
Forum: Soap Box 2011-09-27, 05:34 Replies: 1,649 Views: 87,804 Posted By Wacky But, it is just your opinion that it should be a... But, it is just your opinion that it should be a requirement that "M" implies "L". Although you have reasoned argument to advocate it, that is not a presently accepted requirement. And, you are...
Forum: Soap Box 2011-09-26, 17:36 Replies: 1,649 Views: 87,804 Posted By Wacky Now, I think that it is appropriate to point to a... Now, I think that it is appropriate to point to a logical fallacy. I would say that you present an argument that marriage should include love, etc. -- Perhaps, more formally, that for a marriage...
Forum: Soap Box 2011-09-25, 15:37 Replies: 1,649 Views: 87,804 Posted By Wacky Here, you appear to be claiming that your... Here, you appear to be claiming that your interpretation of "marriage" is rational. Zeta-Flux did not, in any way, claim that your interpretation was irrational. He did claim that there are other...
Forum: Soap Box 2011-09-24, 22:29 Replies: 1,649 Views: 87,804 Posted By Wacky No, by law, a man and a woman are allowed to... No, by law, a man and a woman are allowed to marry, with some limits. That law may have the effect that you note. However, as worded, each individual man or woman is afforded the same "right" to...
Forum: Soap Box 2011-09-24, 21:33 Replies: 1,649 Views: 87,804 Posted By Wacky I'm sorry, but you are wrong. Motivation does not... I'm sorry, but you are wrong. Motivation does not create the right, the wording of the law does. As things currently stand, in most jurisdictions, the law does not grant the right. Whether, or not,...
Forum: Factoring 2011-07-22, 11:45 Replies: 20 Views: 3,191 Posted By Wacky Do it! One Ring to rule them all, One Ring... Do it! One Ring to rule them all, One Ring to find them, One Ring to bring them all and in the darkness bind them. Yes, Bob, I know the definition of "Field" and "Ring". But "One Field" just...
Forum: Cunningham Tables 2011-04-25, 13:31 Replies: 5 Views: 7,501 Posted By Wacky Bob, What website? AFAIK, NFSNet has been... Bob, What website? AFAIK, NFSNet has been inactive for some time now. Richard
2011-03-29, 14:21 Replies: 26 Views: 4,208 Posted By Wacky I will repeat William's request. Show us the... I will repeat William's request. Show us the framework from which the equations are derived. I suspect that your variables and equations could be expressed in a matrix notation that would be much...
2011-02-04, 13:51 Replies: 410 Views: 19,182 Posted By Wacky No. The difference is that you have specified ANY... No. The difference is that you have specified ANY sets, A and B which are elements of C. They have excluded certain pairs of sets. Which pairs have they excluded? Why is that important?
2011-02-04, 12:55 Replies: 410 Views: 19,182 Posted By Wacky Do you see the difference between your definition... Do you see the difference between your definition and theirs?
Forum: Soap Box 2011-01-28, 15:53 Replies: 21 Views: 1,005 Posted By Wacky In some jurisdictions, there are two, or more,... In some jurisdictions, there are two, or more, sentences which are more severe than "life". Since most sentences come with the possibility of parole, and, for that purpose, "life" is treated as...
2011-01-25, 14:13 Replies: 410 Views: 19,182 Posted By Wacky I think that you may understand the concept, but... I think that you may understand the concept, but not how to properly express the counter example. Try it like this: Assume that A and B are male parents and that E and F are a female parents. ...
Forum: Lounge 2011-01-23, 19:52 Replies: 31 Views: 2,866 Posted By Wacky That number is much more comparable to my USSD... That number is much more comparable to my USSD $0.089/kWh. Wow! You certainly have a lot added on -- the "extra" is 150% of the cost-of-goods. I can see 20%, or so, as VAT/sales tax. But where... Forum: Forum Feedback 2011-01-23, 19:42 Replies: 40 Views: 4,697 Posted By Wacky Actually, it should not be too hard to manage.... Actually, it should not be too hard to manage. Everyone starts in the "standard" class and then those who demonstrate that they deserve it are "promoted" to a special class that has (perhaps... Forum: Lounge 2011-01-23, 15:52 Replies: 31 Views: 2,866 Posted By Wacky It is very hard to compare things on that basis.... It is very hard to compare things on that basis. In my situation, there are no additional taxes. Additionally, many of the electric utilities in Texas are still owned by the local governments. Those... Forum: Lounge 2011-01-22, 20:08 Replies: 31 Views: 2,866 Posted By Wacky USD$0.089/kWh, but 5% of that amount is my... USD \$0.089/kWh, but 5% of that amount is my proration of a fixed "availability" charge. We get a lower rate in the winter than in the summer. In the summer, to meet peak demand, they have to use...
Forum: Puzzles 2011-01-21, 22:43 Replies: 11 Views: 1,873 Posted By Wacky 100 dices "Dices" is a perfectly good word. Unfortunately, it is usually used as a verb. So cut the guy some slack.
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https://www.saranextgen.com/homeworkhelp/doubts.php?id=50249 | # Two forces P and Q of magnitude 2F and 3F, respectively, are at an angle with each other. If the force Q is doubled, then their resultant also gets doubled. Then, the angle is: (a) 300 (b) 600 (c) 900 (d) 1200
## Question ID - 50249 :- Two forces P and Q of magnitude 2F and 3F, respectively, are at an angle with each other. If the force Q is doubled, then their resultant also gets doubled. Then, the angle is: (a) 300 (b) 600 (c) 900 (d) 1200
3537
4F2+9F2+12F2cos=R2
4F2+36 F2+24 F2 cos=4R2
4F2+36 F2+24 F2cos
=4(13F2+12F2cos)= 52 F2 +48F2cos
cos ==
Next Question :
The actual value resistance R, shown in the figure is 30. This is measured in an experiment as showing using the standard formula R=, where V and I are the readings of the voltmeter and ammeter, respectively. If the measured value of R is 5% less, then the internal resistance of the voltmeter is: (a) 350 (b) 570 (c) 35 (d) 600 | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.958806037902832, "perplexity": 1405.8346419313295}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-49/segments/1669446710533.96/warc/CC-MAIN-20221128135348-20221128165348-00765.warc.gz"} |
https://courses.cs.cornell.edu/cs2800/wiki/index.php/SP20:Lecture_3_prep | # SP20:Lecture 3 prep
Please come to lecture 3 knowing the following definitions (you can click on the terms or symbols for more information, or you can review the entire lecture notes from last semester here):
Definition: Subset
If and are sets, then is a subset of (written ) if every is also in
Definition: Power set
The power set of a set (written )is the set of all subsets of . Formally, .
Definition: Union
If and are sets, then the union of and (written ) is given by .
Definition: Intersection
If and are sets, then the intersection of and (written ) is given by .
Definition: Set difference
If and are sets, then the set difference minus (written ) is given by . | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9152601361274719, "perplexity": 1520.570534711383}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-43/segments/1634323587659.72/warc/CC-MAIN-20211025092203-20211025122203-00638.warc.gz"} |
http://swmath.org/software/9154 | # CPsuperH
CPsuperH: a computational tool for Higgs phenomenology in the minimal supersymmetric standard model with explicit CP-violation. We provide a detailed description of the Fortran code CPsuperH, a newly-developed computational package that calculates the mass spectrum and decay widths of the neutral and charged Higgs bosons in the Minimal Supersymmetric Standard Model with explicit CP violation. The program is based on recent renormalization-group-improved diagrammatic calculations that include dominant higher-order logarithmic and threshold corrections, b-quark Yukawa-coupling resummation effects and Higgs-boson pole-mass shifts. The code CPsuperH is self-contained (with all subroutines included), is easy and fast to run, and is organized to allow further theoretical developments to be easily implemented. 1 The fact that the masses and couplings of the charged and neutral Higgs bosons are computed at a similar high-precision level makes it an attractive tool for Tevatron, LHC and LC studies, also in the CP-conserving case.
## Keywords for this software
Anything in here will be replaced on browsers that support the canvas element
## References in zbMATH (referenced in 11 articles , 1 standard article )
Showing results 1 to 11 of 11.
Sorted by year (citations) | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9204556941986084, "perplexity": 2162.542275724272}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-39/segments/1568514578201.99/warc/CC-MAIN-20190923193125-20190923215125-00515.warc.gz"} |
http://www.zora.uzh.ch/23837/ | # Measurement of diffractive scattering of photons with large momentum transfer at HERA
Aaron, F D; Alexa, C; Andreev, V; Antunovic, B; Aplin, S; Müller, K; Nowak, K; Robmann, P; Schmitz, C; Schöning, A; Straumann, U; Truöl, P; H1 Collaboration (2009). Measurement of diffractive scattering of photons with large momentum transfer at HERA. Physics Letters B, 672(3):219-226.
## Abstract
The first measurement of diffractive scattering of quasi-real photons with large momentum transfer γp→γY, where Y is the proton dissociative system, is made using the H1 detector at HERA. The measurement is performed for initial photon virtualities Q2<0.01 GeV2. Single differential cross sections are measured as a function of W, the incident photon–proton centre of mass energy, and t, the square of the four-momentum transferred at the proton vertex, in the range 175<W<247 GeV and 4<|t|<36 GeV2. The W dependence is well described by a model based on perturbative QCD using a leading logarithmic approximation of the BFKL evolution. The measured |t| dependence is harder than that predicted by the model and those observed in exclusive vector meson production.
The first measurement of diffractive scattering of quasi-real photons with large momentum transfer γp→γY, where Y is the proton dissociative system, is made using the H1 detector at HERA. The measurement is performed for initial photon virtualities Q2<0.01 GeV2. Single differential cross sections are measured as a function of W, the incident photon–proton centre of mass energy, and t, the square of the four-momentum transferred at the proton vertex, in the range 175<W<247 GeV and 4<|t|<36 GeV2. The W dependence is well described by a model based on perturbative QCD using a leading logarithmic approximation of the BFKL evolution. The measured |t| dependence is harder than that predicted by the model and those observed in exclusive vector meson production.
## Citations
3 citations in Web of Science®
8 citations in Scopus®
## Altmetrics
Detailed statistics
Item Type: Journal Article, refereed, original work 07 Faculty of Science > Physics Institute 530 Physics English 23 February 2009 25 Nov 2009 16:05 05 Apr 2016 13:32 Elsevier 0370-2693 10.1016/j.physletb.2009.01.019 http://arxiv.org/abs/0810.3096v2
Permanent URL: http://doi.org/10.5167/uzh-23837 | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9712519645690918, "perplexity": 5030.639646319823}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-40/segments/1474738662018.69/warc/CC-MAIN-20160924173742-00137-ip-10-143-35-109.ec2.internal.warc.gz"} |
http://planetmath.org/rigid | # rigid
## Primary tabs
Synonym:
rigidity result, rigidity theorem, rigidity
Type of Math Object:
Definition
Major Section:
Reference
Groups audience:
## Mathematics Subject Classification
### Rigid
I don't quite understand this definition. To me, it is not clear what a "degree of freedom" is, or what does it mean to be determined by a 'limited' number of them. Limited in what sense? (assuming we know what a degree of freedom is)
### Re: Rigid
I think the intent of the entry is to give a feel for what the notion of rigidity should be, and how it's used in mathematical conversation, rather than a definition of the term itself.
While somewhat nonstandard, I do think entries like this have a place in the encyclopedia...being able to communicate ideas of imprecisely-defined notions is something that mathematicians do. This notion or "rigidity" is yet another piece of vocabulary at their disposal.
So my suggestion for matte is that he make it more clear that this is not a formal definition (actually, I think the first sentence of Version 1 of this entry was pretty good)...how about something like
"The term 'rigid' is used in mathematics to describe a collection of objects in which each object is completely determined by fewer parameters than expected."
Hope this helps,
Cam | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 10, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.5653659105300903, "perplexity": 727.6663825090693}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-04/segments/1484560280242.65/warc/CC-MAIN-20170116095120-00105-ip-10-171-10-70.ec2.internal.warc.gz"} |
http://quant.stackexchange.com/questions/8738/constant-maturity-futures-price-methodology | # Constant maturity futures price methodology
What is the correct methodology to compute constant maturity futures price.
I've met in some papers that do the following. To create constant maturity synthetic futures prices with maturity $m = 30, 60,...,180$ days. We should take a pair of futures that straddle the chosen maturity $m$ with maturities $s<m<l$ measured in days until expiration.
Then the price is derived using the following formula: $$p_m = \alpha p_s + (1-\alpha)p_l,\, \alpha = \frac{l-m}{l-s}$$
1. Should the maturity be rounded to days?
2. What happens when shorter futures comes closer to expiration. On which date and how we roll over the pair? Is it recommended to roll over futures several days before expiration. In this case we should have negative $\alpha$.
3. What are the limitations of this methodology? What are general assumptions?
4. We can take only daily closing prices or we can use more frequent data?
- | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8114233613014221, "perplexity": 1559.422430529851}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-23/segments/1406510274866.27/warc/CC-MAIN-20140728011754-00055-ip-10-146-231-18.ec2.internal.warc.gz"} |
https://human.libretexts.org/Bookshelves/Religious_Studies/Book%3A_Six_Ways_of_Being_Religious_(Cannon)/15%3A_Comparing_Buddhism_and_Christianity_by__Means_of_the_Framework/15.04%3A_Notes | Skip to main content
# 15.4: Notes
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1. See Winston L. King, Zen and the Way of the Sword: Arming the Samurai Psyche (New York: Oxford Unversity Press, 1993); and Marcus Bull, Knightly Piety and the Lay Response to the First Crusade: The Limousin and Gascony c.970-c.1130(New York: Oxford University Press, 1993).
2. It is not clear to me that transcendence of egoism is the ultimate goal in both traditions. It certainly appears to be so in certain formulations of Buddhism, whereas most knowledgeable Christians would consider it only part of the goal, a penultimate goal, or a by-product of attaining the goal of at-onement with God in Christ.
3. See Julia Ching,"Paradigms of the Self in Buddhism and Christianity,"Buddhist Christian Studies 4 (1984), 31-50; and Winston L. King, "No-Self, No-Mind, and Emptiness Revisited," Buddhist-Christian Dialogue: Mutual Renewal and Transformation, eds. Paul 0. Ingram and Frederick]. Streng (Honolulu: University of Hawaii Press, 1986), pp. 155-176.
4. See the recommended readings at the end of this chapter.
This page titled 15.4: Notes is shared under a CC BY-NC 4.0 license and was authored, remixed, and/or curated by Dale Cannon (Independent) via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.
• Was this article helpful? | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8280996084213257, "perplexity": 5929.632368273023}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-33/segments/1659882570879.1/warc/CC-MAIN-20220808213349-20220809003349-00758.warc.gz"} |
http://astrophysicsformulas.com/astronomy-formulas-astrophysics-formulas/temperature-in-kelvin-to-kev-conversion/ | # Temperature in Kelvin to keV Conversion
Practicing astrophysicists routinely refer to temperatures in units of eV or keV, even though this is wrong, because temperature is not dimensionally equivalent to energy. Nevertheless, they still do it, with the Boltzmann constant being implicitly included in the conversion. Here are formulas for temperature in Kelvin to keV conversion.
$E({\rm eV}) = \frac{kT}{e}$
because 1 eV is by definition the energy required to move a charge $e$ through a potential difference of 1 volt and is equal to $1.6 \times 10^{-19} \times 1$ Joules. Thus
$T \ ({\rm eV}) = 8.625 \times 10^{-5} \ T \ ({\rm Kelvin})$
and
$T \ ({\rm keV}) = 8.625 \ \times 10^{-4} \left(\frac{T \ ({\rm Kelvin})}{10^{4} \ {\rm Kelvin}} \right)$
where $k=1.3806504 \times 10^{-23}$ Joules/Kelvin is the Boltzmann constant (source: NIST).
Details:
With $k=1.38 \times 10^{-23} \ \rm J \ K^{-1}$, $kT({\rm Kelvin})$ is in Joules, divide by the electron charge, $e$, to get eV, then divide by 1000 to get keV:
$\frac{k}{1000 e} = \frac{1.38 \times 10^{-23}}{1000 \times 1.6 \times 10^{-19}} = 8.625 \times 10^{-8}$ | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 2, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8392608165740967, "perplexity": 746.5204306263829}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-51/segments/1512948594665.87/warc/CC-MAIN-20171217074303-20171217100303-00113.warc.gz"} |
https://toywiki.xyz/discrete_dlpp_dp.html | # Discrete directed last passage percolations and directed polymers
directed_last_passage_percolation directed_polymer
Definition. The directed last passage percolation (DLPP) $$Z_0(n, m)$$ on integer lattice $$\pint_{>0} \times \pint_{>0}$$, where each vertex $$(i, j)$$ has weight $$a_{ij}$$, is defined as the maximum over directed paths from $$(1, 1)$$ to $$(n, m)$$:
$Z_0(n, m) = \max_{\pi: (1, 1) \to (n, m)} \sum_{(i, j) \in \pi_i} a_{ij}, \qquad (1)$
where recall from Greene's theorem that a directed path $$\pi: (1, 1) \to (n, m)$$ is a collection of coordinates $$(n_1, k_1) = (1, 1), (n_2, k_2), ..., (n_{r - 1}, k_{r - 1}), (n_r, k_r) = (n, m)$$ such that
$(n_i - n_{i - 1}, k_i - k_{i - 1}) \in \{(0, 1), (1, 0)\}.$
Definition. The directed polymer (DP) $$Z_1(n, m)$$ is defined as a geometric lifting of the $$Z_0(n, m)$$:
$Z_1(n, m) = \log \left(\sum_{\pi: (1, 1) \to (n, m)} \prod_{(i, j) \in \pi} e^{a_{ij}}\right). \qquad (2)$
The DLPP (or the Manhattan Tourist problem) is a typical example of dynamic programming, where one can rely on the recursive formula:
$Z_0(n, m) = (Z_0(n - 1, m) \vee Z_0(n, m - 1)) + a_{nm}. \qquad (3)$
Similarly for DP:
$Z_1(n, m) = \log(\exp(Z_1(n - 1, m)) + \exp(Z_1(n, m - 1))) + a_{nm}$
And these formulas in turn are alternative definitions of the DLPP and DP.
Let us focus on a square enclosed by vertices $$(n - 1, m - 1), (n - 1, m), (n, m - 1), (n, m)$$. By defining for $$b = 0, 1$$
\begin{align} U_b &= Z_b(n, m - 1) - Z_b(n - 1, m - 1) \\ V_b &= Z_b(n - 1, m) - Z_b(n - 1, m - 1) \\ X_b &= a_{n, m} \\ U_b' &= Z_b(n, m) - Z_b(n - 1, m) \\ V_b' &= Z_b(n, m) - Z_b(n, m - 1) \end{align}
By writing $$X_b' = U_b - U_b' + X_b$$ one can derive that $$U_b, V_b, X_b, U_b', V_b', X_b'$$ satisfy the Case 1 and 3 of the Burke property respectively when $$b = 0, 1$$.
Due to this link, we define the $$q$$- and $$qt$$-analog of the DLPP according to Case 4 and 5 of the Burke property:
Definition. We define the $$q$$- and $$qt$$-analog of the DLPP as follows:
\begin{align} Z (1, 1) &= a_{1, 1} \\ Z (n, 1) &= a_{n, 1} + Z (n - 1, 1), \qquad n > 1 \\ Z (1, m) &= a_{1, m} + Z (1, n - 1), \qquad m > 1 \\ Z (n, m) &= a_{n, m} + Z (n - 1, m) + Z (n, m - 1) - Z (n - 1, m - 1) - X'(n, m), \qquad m, n > 1. \end{align}
where
1. for $$q$$-analog: $X'(n, m) \sim q\text{Hyp}(Z(n, m - 1) - Z(n - 1, m - 1), \infty, Z(n - 1, m) - Z(n - 1, m - 1))$ where $$q$$Hyp is the q-hypergeometric distribution.
2. for $$qt$$-analog: $X'(n, m) \sim qt\text{IHyp}(Z(n, m - 1) - Z(n - 1, m - 1), Z(n - 1, m) - Z(n - 1, m - 1))$ where $$qt$$IHyp is the $$qt$$-infhypergeometric distribution defined in burke_property.
Remark. As per burke_property, the $$qt$$DLPP reduces to the $$q$$DLPP when $$t = 0$$, and to the usual DLPP when $$t = q$$.
Open. Find a global definition for the $$q$$- and $$qt$$-DLPP (like (1)(2) in the language of directed paths), i.e. analogues of greene_theorem restricted to the first row of the output tableaux.
The Burke property results in strong law of large numbers in the DLPP and DP models with equilibrium boundary conditions. Here we give the $$qt$$-version. The other cases are similar.
Definition. Let $$0 < \alpha, \beta < 1$$. The $$qt$$-deformed DLPP with equilibrium boundary condition is the one on integer lattice $$\pint \times \pint$$ with the following weights:
\begin{align} a_{0, 0} &\equiv 0 \\ a_{n, 0} &\sim qt\text{Geom}(\alpha), \qquad n > 0 \\ a_{0, m} &\sim qt\text{Geom}(\beta), \qquad m > 0 \\ a_{n, m} &\sim qt\text{Geom}(\alpha\beta), \qquad m, n > 0. \end{align}
Claim. Consider the $$qt$$-deformed DLPP with equilibrium boundary condition, we have almost surely
$\lim_{N \to \infty} {Z(\lfloor N x \rfloor, \lfloor N y \rfloor) \over N} = x \gamma(\alpha) + y \gamma(\beta),$
where $$\gamma(\alpha)$$ is the first moment of $$qt\text{Gemo}(\alpha)$$.
Proof. Similar to that of the version of DLPP with geometric weights ($$q = t$$) in e.g. Theorem 4.12 of [{romik14}]. $$\square$$
## References
• [romik14] The surprising mathematics of longest increasing subsequences, , 2014. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 3, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9999914169311523, "perplexity": 1318.8011558253202}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-17/segments/1618038077810.20/warc/CC-MAIN-20210414095300-20210414125300-00374.warc.gz"} |
https://worldwidescience.org/topicpages/a/acoustic+noise.html | #### Sample records for acoustic noise
1. Acoustics Noise Test Cell
Federal Laboratory Consortium — The Acoustic Noise Test Cell at the NASA/Caltech Jet Propulsion Laboratory (JPL) is located adjacent to the large vibration system; both are located in a class 10K...
2. Acoustic Imaging of Combustion Noise
Ramohalli, K. N.; Seshan, P. K.
1984-01-01
Elliposidal acoustic mirror used to measure sound emitted at discrete points in burning turbulent jets. Mirror deemphasizes sources close to target source and excludes sources far from target. At acoustic frequency of 20 kHz, mirror resolves sound from region 1.25 cm wide. Currently used by NASA for research on jet flames. Produces clearly identifiable and measurable variation of acoustic spectral intensities along length of flame. Utilized in variety of monitoring or control systems involving flames or other reacting flows.
3. Identification of Turbomachinery Noise Sources Using Acoustical Holography Project
National Aeronautics and Space Administration — Evaluation and enhancement of the acoustical performance of turbomachinery requires knowledge of the acoustic sources. However, the noise generation mechanisms...
4. Aero-acoustic noise of wind turbines. Noise prediction models
Maribo Pedersen, B. [ed.
1997-12-31
Semi-empirical and CAA (Computational AeroAcoustics) noise prediction techniques are the subject of this expert meeting. The meeting presents and discusses models and methods. The meeting may provide answers to the following questions: What Noise sources are the most important? How are the sources best modeled? What needs to be done to do better predictions? Does it boil down to correct prediction of the unsteady aerodynamics around the rotor? Or is the difficult part to convert the aerodynamics into acoustics? (LN)
5. Airframe Noise Prediction by Acoustic Analogy: Revisited
Farassat, F.; Casper, Jay H.; Tinetti, A.; Dunn, M. H.
2006-01-01
The present work follows a recent survey of airframe noise prediction methodologies. In that survey, Lighthill s acoustic analogy was identified as the most prominent analytical basis for current approaches to airframe noise research. Within this approach, a problem is typically modeled with the Ffowcs Williams and Hawkings (FW-H) equation, for which a geometry-independent solution is obtained by means of the use of the free-space Green function (FSGF). Nonetheless, the aeroacoustic literature would suggest some interest in the use of tailored or exact Green s function (EGF) for aerodynamic noise problems involving solid boundaries, in particular, for trailing edge (TE) noise. A study of possible applications of EGF for prediction of broadband noise from turbulent flow over an airfoil surface and the TE is, therefore, the primary topic of the present work. Typically, the applications of EGF in the literature have been limited to TE noise prediction at low Mach numbers assuming that the normal derivative of the pressure vanishes on the airfoil surface. To extend the application of EGF to higher Mach numbers, the uniqueness of the solution of the wave equation when either the Dirichlet or the Neumann boundary condition (BC) is specified on a deformable surface in motion. The solution of Lighthill s equation with either the Dirichlet or the Neumann BC is given for such a surface using EGFs. These solutions involve both surface and volume integrals just like the solution of FW-H equation using FSGF. Insight drawn from this analysis is evoked to discuss the potential application of EGF to broadband noise prediction. It appears that the use of a EGF offers distinct advantages for predicting TE noise of an airfoil when the normal pressure gradient vanishes on the airfoil surface. It is argued that such an approach may also apply to an airfoil in motion. However, for the prediction of broadband noise not directly associated with a trailing edge, the use of EGF does not
6. Shaping and Timing Gradient Pulses to Reduce MRI Acoustic Noise
Segbers, Marcel; Sierra, Carlos V. Rizzo; Duifhuis, Hendrikus; Hoogduin, Johannes M.
2010-01-01
A method to reduce the acoustic noise generated by gradient systems in MRI has been recently proposed; such a method is based on the linear response theory. Since the physical cause of MRI acoustic noise is the time derivative of the gradient current, a common trapezoid current shape produces an aco
7. Adaptive Drainage Slots for Acoustic Noise Attenuation Project
National Aeronautics and Space Administration — Cornerstone Research Group, Inc. (CRG), proposes to demonstrate feasibility in the reduction of noise attributed to drainage slots in jet engine acoustic liners....
8. Advanced Acoustic Blankets for Improved Aircraft Interior Noise Reduction Project
National Aeronautics and Space Administration — In this project advanced acoustic blankets for improved low frequency interior noise control in aircraft will be developed and demonstrated. The improved performance...
9. Adaptive Drainage Slots for Acoustic Noise Attenuation Project
National Aeronautics and Space Administration — Cornerstone Research Group, Inc. (CRG) demonstrated feasibility in the reduction of noise attributed to drainage slots in jet engine acoustic liners. This was...
10. Active-passive gradient shielding for MRI acoustic noise reduction.
Edelstein, William A; Kidane, Tesfaye K; Taracila, Victor; Baig, Tanvir N; Eagan, Timothy P; Cheng, Yu-Chung N; Brown, Robert W; Mallick, John A
2005-05-01
An important source of MRI acoustic noise-magnet cryostat warm-bore vibrations caused by eddy-current-induced forces-can be mitigated by a passive metal shield mounted on the outside of a vibration-isolated, vacuum-enclosed shielded gradient set. Finite-element (FE) calculations for a z-gradient indicate that a 2-mm-thick Cu layer wrapped on the gradient assembly can decrease mechanical power deposition in the warm bore and reduce warm-bore acoustic noise production by about 25 dB. Eliminating the conducting warm bore and other magnet parts as significant acoustic noise sources could lead to the development of truly quiet, fully functioning MRI systems with noise levels below 70 dB.
11. High Temperature Acoustic Noise Reduction Materials Project
National Aeronautics and Space Administration — The proposed innovation is to use combustion synthesis techniques to manufacture ceramic-based acoustic liners capable of withstanding temperatures up to 2500?C....
12. Acoustic noise reduction in a 4 T MRI scanner.
Mechefske, Chris K; Geris, Ryan; Gati, Joseph S; Rutt, Brian K
2002-01-01
High-field, high-speed magnetic resonance imaging (MRI) can generate high levels of noise. There is ongoing concern in the medical and imaging research communities regarding the detrimental effects of high acoustic levels on auditory function, patient anxiety, verbal communication between patients and health care workers and ultimately MR image quality. In order to effectively suppress the noise levels inside MRI scanners, the sound field needs to be accurately measured and characterized. This paper presents the results of measurements of the sound radiation from a gradient coil cylinder within a 4 T MRI scanner under a variety of conditions. These measurement results show: (1) that noise levels can be significantly reduced through the use of an appropriately designed passive acoustic liner; and (2) the true noise levels that are experienced by patients during echo planar imaging.
13. Passive Acoustic Thermometry Using Low-Frequency Deep Water Noise
2015-09-30
help develop a totally passive means for monitoring the ocean environment using only ambient noise. A potential scenario benefiting from the proposed...Passive structural health monitoring of a high-speed naval ship from ambient vibrations. J. Acoust. Soc. Am. 129, 2991-2999, (2011). 13b. R. Snieder...thermometry using Cross-correlation processing of deep water ambient noise. OBJECTIVE Our previous research effort has demonstrated that coherent
14. An improved probe noise approach for acoustic feedback cancellation
Guo, Meng; Jensen, Søren Holdt; Jensen, Jesper
2012-01-01
-state error of the adaptive algorithm in a multiple-microphone and single-loudspeaker audio system. This is obtained through a specifically designed probe noise signal and a corresponding probe noise enhancement strategy. We show the effects of the proposed probe noise approach by deriving analytical......The perhaps most challenging problem in acoustic feedback cancellation using adaptive filters is the bias problem. It is well-known that a probe noise approach can effectively prevent this problem. However, when the probe noise must be inaudible and the steady-state error of the adaptive filter...... must be unchanged, this approach causes a significantly decreased convergence rate of the adaptive filter, and might thereby be less useful in practical applications. In this work, we propose a new probe noise approach which significantly increases the convergence rate while maintaining the steady...
15. Perceptual learning of acoustic noise generates memory-evoked potentials.
Andrillon, Thomas; Kouider, Sid; Agus, Trevor; Pressnitzer, Daniel
2015-11-01
Experience continuously imprints on the brain at all stages of life. The traces it leaves behind can produce perceptual learning [1], which drives adaptive behavior to previously encountered stimuli. Recently, it has been shown that even random noise, a type of sound devoid of acoustic structure, can trigger fast and robust perceptual learning after repeated exposure [2]. Here, by combining psychophysics, electroencephalography (EEG), and modeling, we show that the perceptual learning of noise is associated with evoked potentials, without any salient physical discontinuity or obvious acoustic landmark in the sound. Rather, the potentials appeared whenever a memory trace was observed behaviorally. Such memory-evoked potentials were characterized by early latencies and auditory topographies, consistent with a sensory origin. Furthermore, they were generated even on conditions of diverted attention. The EEG waveforms could be modeled as standard evoked responses to auditory events (N1-P2) [3], triggered by idiosyncratic perceptual features acquired through learning. Thus, we argue that the learning of noise is accompanied by the rapid formation of sharp neural selectivity to arbitrary and complex acoustic patterns, within sensory regions. Such a mechanism bridges the gap between the short-term and longer-term plasticity observed in the learning of noise [2, 4-6]. It could also be key to the processing of natural sounds within auditory cortices [7], suggesting that the neural code for sound source identification will be shaped by experience as well as by acoustics.
16. Perceptual Learning of Acoustic Noise by Individuals with Dyslexia
Agus, Trevor R.; Carrión-Castillo, Amaia; Pressnitzer, Daniel; Ramus, Franck
2014-01-01
Purpose: A phonological deficit is thought to affect most individuals with developmental dyslexia. The present study addresses whether the phonological deficit is caused by difficulties with perceptual learning of fine acoustic details. Method: A demanding test of nonverbal auditory memory, "noise learning," was administered to both…
17. Development of an acoustic actuator for launch vehicle noise reduction.
Henderson, Benjamin K; Lane, Steven A; Gussy, Joel; Griffin, Steve; Farinholt, Kevin M
2002-01-01
In many active noise control applications, it is necessary that acoustic actuators be mounted in small enclosures due to volume constraints and in order to remain unobtrusive. However, the air spring of the enclosure is detrimental to the low-frequency performance of the actuator. For launch vehicle noise control applications, mass and volume constraints are very limiting, but the low-frequency performance of the actuator is critical. This work presents a novel approach that uses a nonlinear buckling suspension system and partial evacuation of the air within the enclosure to yield a compact, sealed acoustic driver that exhibits a very low natural frequency. Linear models of the device are presented and numerical simulations are given to illustrate the advantages of this design concept. An experimental prototype was built and measurements indicate that this design can significantly improve the low-frequency response of compact acoustic actuators.
18. Airframe noise measurements by acoustic imaging
Kendall, J. M.
1977-01-01
Studies of the noise produced by flow past wind tunnel models are presented. The central objective of these is to find the specific locations within a flow which are noisy, and to identify the fluid dynamic processes responsible, with the expectation that noise reduction principles will be discovered. The models tested are mostly simple shapes which result in types of flow that are similar to those occurring on, for example, aircraft landing gear and wheel cavities. A model landing gear and a flap were also tested. Turbulence has been intentionally induced as appropriate in order to simulate full-scale effects more closely. The principal technique involves use of a highly directional microphone system which is scanned about the flow field to be analyzed. The data so acquired are presented as a pictorial image of the noise source distribution. An important finding is that the noise production is highly variable within a flow field and that sources can be attributed to various fluid dynamic features of the flow. Flow separation was not noisy, but separation closure usually was.
19. Acoustic FMRI noise: linear time-invariant system model.
Rizzo Sierra, Carlos V; Versluis, Maarten J; Hoogduin, Johannes M; Duifhuis, Hendrikus Diek
2008-09-01
Functional magnetic resonance imaging (fMRI) enables sites of brain activation to be localized in human subjects. For auditory system studies, however, the acoustic noise generated by the scanner tends to interfere with the assessments of this activation. Understanding and modeling fMRI acoustic noise is a useful step to its reduction. To study acoustic noise, the MR scanner is modeled as a linear electroacoustical system generating sound pressure signals proportional to the time derivative of the input gradient currents. The transfer function of one MR scanner is determined for two different input specifications: 1) by using the gradient waveform calculated by the scanner software and 2) by using a recording of the gradient current. Up to 4 kHz, the first method is shown as reliable as the second one, and its use is encouraged when direct measurements of gradient currents are not possible. Additionally, the linear order and average damping properties of the gradient coil system are determined by impulse response analysis. Since fMRI is often based on echo planar imaging (EPI) sequences, a useful validation of the transfer function prediction ability can be obtained by calculating the acoustic output for the EPI sequence. We found a predicted sound pressure level (SPL) for the EPI sequence of 104 dB SPL compared to a measured value of 102 dB SPL. As yet, the predicted EPI pressure waveform shows similarity as well as some differences with the directly measured EPI pressure waveform.
20. Shaping and timing gradient pulses to reduce MRI acoustic noise.
Segbers, Marcel; Rizzo Sierra, Carlos V; Duifhuis, Hendrikus; Hoogduin, Johannes M
2010-08-01
A method to reduce the acoustic noise generated by gradient systems in MRI has been recently proposed; such a method is based on the linear response theory. Since the physical cause of MRI acoustic noise is the time derivative of the gradient current, a common trapezoid current shape produces an acoustic gradient coil response mainly during the rising and falling edge. In the falling edge, the coil acoustic response presents a 180 degrees phase difference compared to the rising edge. Therefore, by varying the width of the trapezoid and keeping the ramps constant, it is possible to suppress one selected frequency and its higher harmonics. This value is matched to one of the prominent resonance frequencies of the gradient coil system. The idea of cancelling a single frequency is extended to a second frequency, using two successive trapezoid-shaped pulses presented at a selected interval. Overall sound pressure level reduction of 6 and 10 dB is found for the two trapezoid shapes and a single pulse shape, respectively. The acoustically optimized pulse shape proposed is additionally tested in a simulated echo planar imaging readout train, obtaining a sound pressure level reduction of 12 dB for the best case.
1. Performing Active Noise Control and Acoustic Experiments Remotely
Imran Khan
2012-12-01
Full Text Available This paper presents a novel and advanced remotely controlled laboratory for conducting Active Noise Control (ANC, acoustic and Digital Signal Processing (DSP experiments. The laboratory facility, recently developed by Blekinge Institute of Technology (BTH Sweden, supports remote learning through internet covering beginners level such as simple experimental measurements to advanced users and even researchers such as algorithm development and their performance evaluation on DSP. The required software development for ANC algorithms and equipment control are carried out anywhere in the world remotely from an internet-connected client PC using a standard web browser. The paper describes in detail how ANC, acoustic and DSP experiments can be performed remotely The necessary steps involved in an ANC experiment such as validity of ANC, forward path estimation and active control applied to a broad band random noise [0-200Hz] in a ventilation duct will be described in detail. The limitations and challenges such as the forward path and nonlinearities pertinent to the remote laboratory setup will be described for the guidance of the user. Based on the acoustic properties of the ventilation duct some of the possible acoustic experiments such as mode shapes analysis and standing waves analysis etc. will also be discussed in the paper.
2. Topography and biological noise determine acoustic detectability on coral reefs
Cagua, Edgar F.
2013-08-19
Acoustic telemetry is an increasingly common tool for studying the movement patterns, behavior and site fidelity of marine organisms, but to accurately interpret acoustic data, the variability, periodicity and range of detectability between acoustic tags and receivers must be understood. The relative and interactive effects of topography with biological and environmental noise have not been quantified on coral reefs. We conduct two long-term range tests (1- and 4-month duration) on two different reef types in the central Red Sea to determine the relative effect of distance, depth, topography, time of day, wind, lunar phase, sea surface temperature and thermocline on detection probability. Detectability, as expected, declines with increasing distance between tags and receivers, and we find average detection ranges of 530 and 120 m, using V16 and V13 tags, respectively, but the topography of the reef can significantly modify this relationship, reducing the range by ~70 %, even when tags and receivers are in line-of-sight. Analyses that assume a relationship between distance and detections must therefore be used with care. Nighttime detection range was consistently reduced in both locations, and detections varied by lunar phase in the 4-month test, suggesting a strong influence of biological noise (reducing detection probability up to 30 %), notably more influential than other environmental noises, including wind-driven noise, which is normally considered important in open-water environments. Analysis of detections should be corrected in consideration of the diel patterns we find, and range tests or sentinel tags should be used for more than 1 month to quantify potential changes due to lunar phase. Some studies assume that the most usual factor limiting detection range is weather-related noise; this cannot be extrapolated to coral reefs. © 2013 Springer-Verlag Berlin Heidelberg.
3. Topography and biological noise determine acoustic detectability on coral reefs
Cagua, E. F.; Berumen, M. L.; Tyler, E. H. M.
2013-12-01
Acoustic telemetry is an increasingly common tool for studying the movement patterns, behavior and site fidelity of marine organisms, but to accurately interpret acoustic data, the variability, periodicity and range of detectability between acoustic tags and receivers must be understood. The relative and interactive effects of topography with biological and environmental noise have not been quantified on coral reefs. We conduct two long-term range tests (1- and 4-month duration) on two different reef types in the central Red Sea to determine the relative effect of distance, depth, topography, time of day, wind, lunar phase, sea surface temperature and thermocline on detection probability. Detectability, as expected, declines with increasing distance between tags and receivers, and we find average detection ranges of 530 and 120 m, using V16 and V13 tags, respectively, but the topography of the reef can significantly modify this relationship, reducing the range by ~70 %, even when tags and receivers are in line-of-sight. Analyses that assume a relationship between distance and detections must therefore be used with care. Nighttime detection range was consistently reduced in both locations, and detections varied by lunar phase in the 4-month test, suggesting a strong influence of biological noise (reducing detection probability up to 30 %), notably more influential than other environmental noises, including wind-driven noise, which is normally considered important in open-water environments. Analysis of detections should be corrected in consideration of the diel patterns we find, and range tests or sentinel tags should be used for more than 1 month to quantify potential changes due to lunar phase. Some studies assume that the most usual factor limiting detection range is weather-related noise; this cannot be extrapolated to coral reefs.
4. Acoustic noise simulation for switched reluctance motors with audible output p
Rasmussen, P.O.; Blaabjerg, F.; Pedersen, J.K.; Kjaer, P.C. [Aalborg Univ., Inst. of Energy Technology (Denmark); Miller, T.J.E. [Univ. of Glasgow, SPEED Lab., Dep. of Electronics and Electrical Engineering (United Kingdom)
1999-07-01
Acoustic noise in switched reluctance motors is one of the last problems which have to be solved before a more widespread use will come. In order to design a low noise Switched Reluctance Motor drive, simulation tools are needed, and this paper describes a design programme where acoustic noise of electromagnetic origin can be estimated and even be heard by the motor-designer. The design program is based on a new, simple developed vibrational and acoustic model where the parameters can be calculated based on the geometry of the motor. The vibrational and acoustic model is verified in both time and frequency domain where vibrations and acoustic noise have been considered. (au)
5. Analysis of Vibration and Acoustic Noise in Permanent Magnet Motors.
Hwang, Sangmoon
The drive motor is a frequent source of vibration and acoustic noise in many precision spindle motors. One of the electromagnetic sources of vibration in permanent magnet motors is the torque ripple, consisting of the reluctance torque and electromagnetic torque fluctuation. This type of vibration is becoming more serious with the advent of new high-grade magnets with increased flux density. Acoustic noise of electromagnetic origin is difficult to predict and its exact mechanism is unclear. The mechanism of noise generation should be revealed to design a quieter motor which is the modern customer's demand. For motor operation at low speeds and loads, torque ripple due to the reluctance torque is often a source of vibration and control difficulty. The reluctance torque in a motor was calculated from the flux density by a finite element method and the Maxwell stress method. Effects of design parameters, such as stator slot width, permanent slot width, airgap length and magnetization direction, were investigated. Magnet pole shaping, by gradually decreasing the magnet thickness toward edges, yields a sinusoidal shape of the reluctance torque with reduced harmonics, thus reducing the vibration. This dissertation also presents two motor design techniques: stator tooth notching and rotor pole skewing with magnet pole shaping, and the effect of each method on the output torque. The analysis shows that the reluctance torque can be nearly eliminated by the suggested designs, with minimal sacrifice of the output torque. In permanent magnet DC motors, the most popular design type is the trapezoidal back electro-motive force (BEMF), for switched DC controllers. It is demonstrated that the output torque profile of one phase energized is qualitatively equivalent to the BEMF profile for motors with reduced reluctance torque. It implies that design of BEMF profile is possible by magnetic modeling of a motor, without expensive and time-consuming experiments for different designs
6. Active vibration and noise control by hybrid active acoustic panels
Stoebener, U.; Gaul, L. [Stuttgart Univ. (Germany). Inst. A fuer Mechanik
2001-07-01
In the present paper a hybrid passive and active treatment for vibration and noise reduction of plate type structures is proposed. The treatment is manufactured as sandwich structure and is called hybrid active acoustic panel. The passive component is used to reduce the vibration and sound radiation for high frequencies whereas the active part of the system is designed for the low frequency range. By selecting the thickness of the passive damping layer a certain frequency limit is defined, which divides the high and low frequency range. The actuator and sensor layout of the active component is evaluated by using the mode shapes of the low frequency range. According to the evaluated layout a hybrid active acoustic panel is manufactured and experimentally tested. The experimental results validate the proposed concept. (orig.)
7. Effects of acoustic noise on the auditory nerve compound action potentials evoked by electric pulse trains.
Nourski, Kirill V; Abbas, Paul J; Miller, Charles A; Robinson, Barbara K; Jeng, Fuh-Cherng
2005-04-01
This study investigated the effects of acoustic noise on the auditory nerve compound action potentials in response to electric pulse trains. Subjects were adult guinea pigs, implanted with a minimally invasive electrode to preserve acoustic sensitivity. Electrically evoked compound action potentials (ECAP) were recorded from the auditory nerve trunk in response to electric pulse trains both during and after the presentation of acoustic white noise. Simultaneously presented acoustic noise produced a decrease in ECAP amplitude. The effect of the acoustic masker on the electric probe was greatest at the onset of the acoustic stimulus and it was followed by a partial recovery of the ECAP amplitude. Following cessation of the acoustic noise, ECAP amplitude recovered over a period of approximately 100-200 ms. The effects of the acoustic noise were more prominent at lower electric pulse rates (interpulse intervals of 3 ms and higher). At higher pulse rates, the ECAP adaptation to the electric pulse train alone was larger and the acoustic noise, when presented, produced little additional effect. The observed effects of noise on ECAP were the greatest at high electric stimulus levels and, for a particular electric stimulus level, at high acoustic noise levels.
8. Acoustic confort at home: Noise emitted by house installations. Recommendations in order to avoid such noise
Jimenez, Santiago
2002-11-01
The present survey consists of the analysis and the study of the solutions used at present in the installations of water supply and elevators. It has been carried out from the acoustic point of view. In order to achieve a thorough study a pilot plant was built in the Laboratory of Acoustics of the School of Industrial Engineering of Terrassa. This pilot plant reproduced different kinds of installations of the water supply in houses. And it has allowed us to systematize the measures and also to determine the optimum solutions from the acoustic perspective. In accordance with the objectives and the process of the survey, the solutions regularly employed in the facilities of water supply and elevators in houses have been analyzed, and levels of noise associated to these facilities have been also presented. A summary of the results obtained in the plant has been included, according to diverse variables. Both the conclusions of the analysis of the data obtained in the laboratory and those of the installations of the houses have been also compared, which has allowed us to describe a series of suggestions with the purpose of reducing the acoustic emission of this type of installations, and increase the acoustic comfort at home. (To be presented in Spanish.)
9. Applied acoustics concepts, absorbers, and silencers for acoustical comfort and noise control alternative solutions, innovative tools, practical examples
Fuchs, Helmut V
2013-01-01
The author gives a comprehensive overview of materials and components for noise control and acoustical comfort. Sound absorbers must meet acoustical and architectural requirements, which fibrous or porous material alone can meet. Basics and applications are demonstrated, with representative examples for spatial acoustics, free-field test facilities and canal linings. Acoustic engineers and construction professionals will find some new basic concepts and tools for developments in order to improve acoustical comfort. Interference absorbers, active resonators and micro-perforated absorbers of different materials and designs complete the list of applications.
10. Acoustic modeling of fan noise generation and scattering in a modular duct system
Nijhof, Marten; Beltman, Marco; Wijnant, Ysbrand; Boer, de André
2005-01-01
Fan noise is an important noise source in computers. The noise spectrum of fans contains tonal noise, found at the so-called Blade Passing Frequency (BPF) and its higher harmonics, that plays an important role in the perceived sound quality. An acoustic resonator integrated in the duct of an in-duct
11. Effects of Classroom Acoustics and Self-Reported Noise Exposure on Teachers' Well-Being
Kristiansen, Jesper; Persson, Roger; Lund, Soren Peter; Shibuya, Hitomi; Nielsen, Per Moberg
2013-01-01
Beyond noise annoyance and voice problems, little is known about the effects that noise and poor classroom acoustics have on teachers' health and well-being. The aim of this field study was therefore to investigate the effects of perceived noise exposure and classroom reverberation on measures of well-being. Data on self-reported noise exposure,…
12. An efficient feedback active noise control algorithm based on reduced-order linear predictive modeling of FMRI acoustic noise.
Kannan, Govind; Milani, Ali A; Panahi, Issa M S; Briggs, Richard W
2011-12-01
Functional magnetic resonance imaging (fMRI) acoustic noise exhibits an almost periodic nature (quasi-periodicity) due to the repetitive nature of currents in the gradient coils. Small changes occur in the waveform in consecutive periods due to the background noise and slow drifts in the electroacoustic transfer functions that map the gradient coil waveforms to the measured acoustic waveforms. The period depends on the number of slices per second, when echo planar imaging (EPI) sequencing is used. Linear predictability of fMRI acoustic noise has a direct effect on the performance of active noise control (ANC) systems targeted to cancel the acoustic noise. It is shown that by incorporating some samples from the previous period, very high linear prediction accuracy can be reached with a very low order predictor. This has direct implications on feedback ANC systems since their performance is governed by the predictability of the acoustic noise to be cancelled. The low complexity linear prediction of fMRI acoustic noise developed in this paper is used to derive an effective and low-cost feedback ANC system.
13. Acoustic noise in deep ice and environmental conditions at the South Pole
Karg, Timo
2008-01-01
To study the acoustic properties of the Antarctic ice the South Pole Acoustic Test Setup (SPATS) was installed in the upper part of drill holes for the IceCube neutrino observatory. An important parameter for the design of a future acoustic neutrino telescope is the acoustic background noise in the ice and its spatial and temporal variations. We study the absolute noise level depth profile from SPATS data and discuss systematic uncertainties. The measured noise is very stable over one year of data taking, and we estimate the absolute noise level to be < 10 mPa in the frequency range from 10 kHz to 50 kHz at depths below 200 m. This noise level is of the same order of magnitude as observed by ocean based acoustic neutrino detection projects in good weather conditions.
14. Characteristics Analysis of Joint Acoustic Echo and Noise Suppression in Periodic Drillstring Waveguide
Li Cheng
2014-01-01
Full Text Available A new method of wireless data telemetry used by oil industry uses compressional acoustic waves to transmit downhole information from the bottom hole to the surface. Unfortunately, acoustic echoes and drilling vibration noises in periodic drillstring are a major issue in transmission performance. A combined acoustic echo and noise suppression method based on wave motion characteristic in drillstring is adopted to enhance an upward-going transmitted acoustic signal. The presented scheme consists of a primary acoustic echo canceller using an array of two accelerometers for dealing with the downward-going noises and a secondary acoustic insulation structure for restraining the upward-going vibration noises. Furthermore, the secondary acoustic insulation structure exhibits a banded and dispersive spectral structure because of periodic groove configuration. By using a finite-differential algorithm for the one-dimensional propagation of longitudinal waves, acoustic receiving characteristics of transmitted signals are simulated with additive Gaussian noise in a periodic pipe structure of limited length to investigate the effects on transmission performance optimization. The results reveal that the proposed scheme can achieve a much lower error bit ratio over a specified acoustic isolation frequency range with a 30–40 dB reduction in the average noise level compared to traditional single-receiver scheme.
15. Acoustic Array Development for Wind Turbine Noise Characterization
Buck, S.; Roadman, J.; Moriarty, P.; Palo, S.
2013-11-01
This report discusses the design and use of a multi-arm, logarithmic spiral acoustic array by the National Renewable Energy Laboratory (NREL) for measurement and characterization of wind turbine-generated noise. The array was developed in collaboration with a team from the University of Colorado Boulder. This design process is a continuation of the elliptical array design work done by Simley. A description of the array system design process is presented, including array shape design, mechanical design, design of electronics and the data acquisition system, and development of post-processing software. System testing and calibration methods are detailed. Results from the initial data acquisition campaign are offered and discussed. Issues faced during this initial deployment of the array are presented and potential remedies discussed.
16. IDENTIFICATION AND MONITORING OF NOISE SOURCES OF CNC MACHINE TOOLS BY ACOUSTIC HOLOGRAPHY METHODS
Jerzy Józwik
2016-06-01
Full Text Available The paper presents the analysis of sound field emitted by selected CNC machine tools. The identification of noise sources and level was measured by acoustic holography for the 3-axis DMC 635eco machine tool and the 5-axis vertical machining centre DMU 65 monoBlock. The acoustic holography method allows precise identification and measurement of noise sources at different bandwidths of frequency. Detection of noise sources in tested objects allows diagnosis of their technical condition, as well as choice of effective means of noise reduction, which is highly significant from the perspective of minimising noise at the CNC machine operator workstation. Test results were presented as acoustic maps in various frequency ranges. Noise sources of the machine tool itself were identified, as well as the range of noise influence and the most frequent places of reflections and their span. The results of measurements were presented in figures and diagrams.
17. The effects of acoustical refurbishment of classrooms on teachers’ perceived noise exposure and noise-related health symptoms
Kristiansen, Jesper; Lund, Søren Peter; Persson, Roger
2015-01-01
Objectives: To investigate whether acoustical refurbishment of classrooms for elementary and lower secondary grade pupils affected teachers’ perceived noise exposure during teaching and noise-related health symptoms. Methods: Two schools (A and B) with a total of 102 teachers were subjected...... of RT and activity sound levels were measured before and after refurbishment. Data on perceived noise exposure, disturbance attributed to different noise sources, voice symptoms, and fatigue after work were collected over a year in a total of six consecutive questionnaires. Results: Refurbished...... classrooms were associated with lower perceived noise exposure and lower ratings of disturbance attributed to noise from equipment in the class compared with unrefurbished classrooms. No associations between the classroom refurbishment and health symptoms were observed. Before acoustical refurbishment...
18. Automatic classification of urban traffic noise onboard an acoustic monitoring system
Wessels, P.W.; Zon, A.T. van; Basten, T.G.H.
2013-01-01
Recent developments in acoustic monitoring systems make it possible to measure complex noise situations, like urban traffic noise, continuously. Monitoring provides more insight in the noise situation, from which more specific and (cost) effective measures can be taken. Monitoring also allows direct
19. Temporal pattern of acoustic imaging noise asymmetrically modulates activation in the auditory cortex.
Ranaweera, Ruwan D; Kwon, Minseok; Hu, Shuowen; Tamer, Gregory G; Luh, Wen-Ming; Talavage, Thomas M
2016-01-01
This study investigated the hemisphere-specific effects of the temporal pattern of imaging related acoustic noise on auditory cortex activation. Hemodynamic responses (HDRs) to five temporal patterns of imaging noise corresponding to noise generated by unique combinations of imaging volume and effective repetition time (TR), were obtained using a stroboscopic event-related paradigm with extra-long (≥27.5 s) TR to minimize inter-acquisition effects. In addition to confirmation that fMRI responses in auditory cortex do not behave in a linear manner, temporal patterns of imaging noise were found to modulate both the shape and spatial extent of hemodynamic responses, with classically non-auditory areas exhibiting responses to longer duration noise conditions. Hemispheric analysis revealed the right primary auditory cortex to be more sensitive than the left to the presence of imaging related acoustic noise. Right primary auditory cortex responses were significantly larger during all the conditions. This asymmetry of response to imaging related acoustic noise could lead to different baseline activation levels during acquisition schemes using short TR, inducing an observed asymmetry in the responses to an intended acoustic stimulus through limitations of dynamic range, rather than due to differences in neuronal processing of the stimulus. These results emphasize the importance of accounting for the temporal pattern of the acoustic noise when comparing findings across different fMRI studies, especially those involving acoustic stimulation.
20. Characterizing response to elemental unit of acoustic imaging noise: an FMRI study.
Tamer, Gregory G; Luh, Wen-Ming; Talavage, Thomas M
2009-07-01
Acoustic imaging noise produced during functional magnetic resonance imaging (fMRI) studies can hinder auditory fMRI research analysis by altering the properties of the acquired time-series data. Acoustic imaging noise can be especially confounding when estimating the time course of the hemodynamic response (HDR) in auditory event-related fMRI (fMRI) experiments. This study is motivated by the desire to establish a baseline function that can serve not only as a comparison to other quantities of acoustic imaging noise for determining how detrimental is one's experimental noise, but also as a foundation for a model that compensates for the response to acoustic imaging noise. Therefore, the amplitude and spatial extent of the HDR to the elemental unit of acoustic imaging noise (i.e., a single ping) associated with echoplanar acquisition were characterized and modeled. Results from this fMRI study at 1.5 T indicate that the group-averaged HDR in left and right auditory cortex to acoustic imaging noise (duration of 46 ms) has an estimated peak magnitude of 0.29% (right) to 0.48% (left) signal change from baseline, peaks between 3 and 5 s after stimulus presentation, and returns to baseline and remains within the noise range approximately 8 s after stimulus presentation.
1. The effect of human activity noise on the acoustic quality in open plan office
Dehlbæk, Tania Stenholt; Jeong, Cheol-Ho; Brunskog, Jonas
2016-01-01
A disadvantage of open plan offices is the noise annoyance. Noise problems in open plan offices have been dealt with in several studies, and standards have been set up. Still, what has not been taken into account is the effect of human activity noise on acoustic conditions. In this study, measure...... D2,S have an impact on the variation in the activity noise. At 1 kHz, the technical background noise influences human activity noise positively. In both octave bands, the human activity noise level varies significantly with the office type, from a call center to a lawyer’s office....
Xu, Jinshan; Deng, Zhiqun; Martinez, Jayson J.; Carlson, Thomas J.; Myers, Joshua R.; Weiland, Mark A.; Jones, Mark E.
2011-09-30
Admiralty Inlet has been selected as a potential tidal energy site. It is located near shipping lanes, is a highly variable acoustic environment, and is frequented by the highly endangered southern resident killer whale (SRKW). Resolving environmental impacts is the first step to receiving approval to deploy tidal turbines at Admiralty Inlet. Of particular concern is the potential for blade strike or other negative interactions between the SRKW and the tidal turbine. A variety of technologies including passive and active monitoring systems are being considered as potential tools to determine the presence of SRKW in the vicinity of the turbines. Broadband noise level measurements are critical for the determination of design and operation specifications of all marine and hydrokinetic energy capture technologies. Acoustic environment data at the proposed site was acquired at different depths using a cabled vertical line array (VLA) with four calibrated hydrophones. The sound pressure level (SPL) power spectrum density was estimated based on the fast Fourier transform. This study describes the first broadband SPL measurements for this site at different depths with frequency ranging from 10 kHz to 480 kHz in combination with other information. To understand the SPL caused by this bedload transport, three different pressure sensors with temperature and conductivity were also assembled on the VLA to measure the conditions at the hydrophone deployment depth. The broadband SPL levels at frequency ranges of 3 kHz to 7 kHz as a function of depth were estimated. Only the hydrophone at an average depth of 40 m showed the strong dependence of SPL with distance from the bottom, which was possibly caused by the cobbles shifting on the seabed. Automatic Identification System data were also studied to understand the SPL measurements.
3. Cylindrical acoustical holography applied to full-scale jet noise.
Wall, Alan T; Gee, Kent L; Neilsen, Tracianne B; Krueger, David W; James, Michael M
2014-09-01
Near-field acoustical holography methods are used to predict sound radiation from an engine installed on a high-performance military fighter aircraft. Cylindrical holography techniques are an efficient approach to measure the large and complex sound fields produced by full-scale jets. It is shown that a ground-based, one-dimensional array of microphones can be used in conjunction with a cylindrical wave function field representation to provide a holographic reconstruction of the radiated sound field at low frequencies. In the current work, partial field decomposition methods and numerical extrapolation of data beyond the boundaries of the hologram aperture are required prior to holographic projection. Predicted jet noise source distributions and directionality are shown for four frequencies between 63 and 250 Hz. It is shown that the source distribution narrows and moves upstream, and that radiation directionality shifts toward the forward direction, with increasing frequency. A double-lobe feature of full-scale jet radiation is also demonstrated.
4. Noise Reduction Evaluation of Multi-Layered Viscoelastic Infinite Cylinder under Acoustical Wave Excitation
Mofakhami, M.R.; H. Hosseini Toudeshky; Sh. Hosseini Hashemi
2008-01-01
In this paper sound transmission through the multilayered viscoelastic air filled cylinders subjected to the incident acoustic wave is studied using the technique of separation of variables on the basis of linear three dimensional theory of elasticity. The effect of interior acoustic medium on the mode maps (frequency vs geometry) and noise reduction is investigated. The effects of internal absorption and external moving medium on noise reduction are also evaluated. The dynamic viscoelastic p...
5. Acoustic fMRI noise : Linear time-invariant system model
Sierra, Carlos V. Rizzo; Versluis, Maarten J.; Hoogduin, Johannes M.; Duifhuis, Hendrikus (Diek)
2008-01-01
Functional magnetic resonance imaging (fMRI) enables sites of brain activation to be localized in human subjects. For auditory system studies, however, the acoustic noise generated by the scanner tends to interfere with the assessments of this activation. Understanding and modeling fMRI acoustic noi
6. Acoustical and Perceptual Comparison of Noise Reduction and Compression in Hearing Aids
Brons, Inge; Houben, Rolph; Dreschler, Wouter A.
2015-01-01
Purpose: Noise reduction and dynamic-range compression are generally applied together in hearing aids but may have opposite effects on amplification. This study evaluated the acoustical and perceptual effects of separate and combined processing of noise reduction and compression. Design: Recordings of the output of 4 hearing aids for speech in…
7. An acoustic vector based approach to locate low frequency noise sources in 3D
Bree, H.-E. de; Ostendorf, C.; Basten, T.
2009-01-01
Although low frequency noise is an issue of huge societal importance, traditional acoustic testing methods have limitations in finding the low frequency source. It is hard to determine the direction of the noise using traditional microphones. Three dimensional sound probes capturing the particle vel
8. Reduction of tire road noise by acoustic absorption: Numerical evaluation of the pass-by noise level reduction using the normal incidence acoustic absorption coefficient
Hamet, J. F.
2004-01-01
Convention GRD2/2000/30202; Rapport de recherche; Comments: This report is an INRETS-LTE edition of the SILVIA -INRETS-013-WP2 report "Estimation of the attenuation of rolling noise by acoustic absorption", dated 19/09/2004. Summary: Part of INRETS task in the SILVIA project is to study the influence of the pavement characteristics on the generation and the propagation of road traffic noise using existing models. This work addresses the reduction of tire-road noise by absorption effects. It a...
9. A First Look at the DGEN380 Engine Acoustic Data from a Core-Noise Perspective
Hultgren, Lennart S.
2015-01-01
This work is a first look at acoustic data acquired in the NASA Glenn Research Center Aero-Acoustic Propulsion Laboratory using the Price Induction DGEN380 small turbofan engine, with particular emphasis on broadband combustor (core) noise. Combustor noise is detected by using a two-signal source separation technique employing one engine-internal sensor and one semi-far-field microphone. Combustor noise is an important core-noise component and is likely to become a more prominent contributor to overall airport community noise due to turbofan design trends, expected aircraft configuration changes, and advances in fan-noise-mitigation techniques. This work was carried out under the NASA Fundamental Aeronautics Program, Fixed Wing Project, Quiet Performance Subproject
10. Characterization of vibration and acoustic noise in a gradient-coil insert.
Yao, G Z; Mechefske, C K; Rutt, B K
2004-09-01
High-speed switching of current in gradient coils within high magnetic field strength magnetic resonance imaging (MRI) scanners results in high acoustic sound pressure levels (SPL) in and around these machines. To characterize the vibration properties as well as the acoustic noise properties of the gradient coil, a finite-element (FE) model was developed using the dimensional design specifications of an available gradient-coil insert and the concentration of the copper windings in the coil. This FE model was then validated using experimentally collected vibration data. A computational acoustic noise model was then developed based on the validated FE model. The validation of the finite-element analysis results was done using experimental modal testing of the same gradient coil in a free-free state (no boundary constraints). Based on the validated FE model, boundary conditions (supports) were added to the model to simulate the operating condition when the gradient-coil insert is in place in an MRI machine. Vibration analysis results from the FE model were again validated through experimental vibration testing with the gradient-coil insert installed in the MRI scanner and excited using swept sinusoidal time waveforms. The simulation results from the computational acoustic noise model were also validated through experimental noise measurement from the gradient-coil insert in the MRI scanner using swept sinusoidal time waveform inputs. Comparisons show that the FE model predicts the vibration properties and the computational acoustic noise model predicts the noise characteristic properties extremely accurately.
11. Modeling hemodynamic responses in auditory cortex at 1.5 T using variable duration imaging acoustic noise.
Hu, Shuowen; Olulade, Olumide; Castillo, Javier Gonzalez; Santos, Joseph; Kim, Sungeun; Tamer, Gregory G; Luh, Wen-Ming; Talavage, Thomas M
2010-02-15
A confound for functional magnetic resonance imaging (fMRI), especially for auditory studies, is the presence of imaging acoustic noise generated mainly as a byproduct of rapid gradient switching during volume acquisition and, to a lesser extent, the radiofrequency transmit. This work utilized a novel pulse sequence to present actual imaging acoustic noise for characterization of the induced hemodynamic responses and assessment of linearity in the primary auditory cortex with respect to noise duration. Results show that responses to brief duration (46 ms) imaging acoustic noise is highly nonlinear while responses to longer duration (>1 s) imaging acoustic noise becomes approximately linear, with the right primary auditory cortex exhibiting a higher degree of nonlinearity than the left for the investigated noise durations. This study also assessed the spatial extent of activation induced by imaging acoustic noise, showing that the use of modeled responses (specific to imaging acoustic noise) as the reference waveform revealed additional activations in the auditory cortex not observed with a canonical gamma variate reference waveform, suggesting an improvement in detection sensitivity for imaging acoustic noise-induced activity. Longer duration (1.5 s) imaging acoustic noise was observed to induce activity that expanded outwards from Heschl's gyrus to cover the superior temporal gyrus as well as parts of the middle temporal gyrus and insula, potentially affecting higher level acoustic processing.
12. Characterization of High-Power Rocket and Jet Noise Using Near-Field Acoustical Holography
2010-01-01
Structural fatigue, hearing damage, and community disturbances are all consequences of rocket and jet noise, especially as they become more powerful. Noise-reduction schemes require accurate characterization of the noise sources within rocket plumes and jets. Nearfield acoustical holography (NAH) measurements were made to visualize the sound field in the jet exhaust region of an F-22 Raptor. This is one of the largest-scale applications of NAH since its development in the 1980s. A scan-based ...
13. Numerical Comparison of Active Acoustic and Structural Noise Control in a Stiffened Double Wall Cylinder
Grosveld, Ferdinand W.
1996-01-01
The active acoustic and structural noise control characteristics of a double wall cylinder with and without ring stiffeners were numerically evaluated. An exterior monopole was assumed to acoustically excite the outside of the double wall cylinder at an acoustic cavity resonance frequency. Structural modal vibration properties of the inner and outer shells were analyzed by post-processing the results from a finite element analysis. A boundary element approach was used to calculate the acoustic cavity response and the coupled structural-acoustic interaction. In the frequency region of interest, below 500 Hz, all structural resonant modes were found to be acoustically slow and the nonresonant modal response to be dominant. Active sound transmission control was achieved by control forces applied to the inner or outer shell, or acoustic control monopoles placed just outside the inner or outer shell. A least mean square technique was used to minimize the interior sound pressures at the nodes of a data recovery mesh. Results showed that single acoustic control monopoles placed just outside the inner or outer shells resulted in better sound transmission control than six distributed point forces applied to either one of the shells. Adding stiffeners to the double wall structure constrained the modal vibrations of the shells, making the double wall stiffer with associated higher modal frequencies. Active noise control obtained for the stiffened double wall configurations was less than for the unstiffened cylinder. In all cases, the acoustic control monopoles controlled the sound transmission into the interior better than the structural control forces.
14. Sediment Acoustics: Wideband Model, Reflection Loss and Ambient Noise Inversion
2011-09-01
grain contact in water- saturated sand," J. Acoust. Soc. Am., vol. 124, pp. EL296-301, (2008). N. P. Chotiros, and M. J. Isakson. "Shear and...34Frame bulk modulus of porous granular marine sediments," J. Acoust. Soc. Am. 120, 699-710, (2006). B. J. Kraft and C. P. de Moustier, "Detailed
15. Aero-Acoustics of Modern Transonic Fans—Fan Noise Reduction from Its Sources
L. Xu; J.D. Denton
2003-01-01
The noise of aerodynamics nature from modern transonic fan is examined from its sources with the perspective of noise reduction through aero-acoustics design using advanced Computational Fluid Dynamics (CFD) tools.In particular the problems associated with the forward propagating noise in the front is addressed. It is identified that the shock wave spillage from the leading edge near the fan tip is the main source of the tone noise. Two different approaches have been studied to reduce the forward arc tone noise and two state-of-art transonic fans are designed using the strategies developed. The following rig tests show that while the fans exhibit other noise problems,the primary goals of noise reduction have been achieved through both fans and the novel noise reduction concept vindicated.
16. Beaked whale (Mesoplodon densirostris) passive acoustic detection in increasing ambient noise.
Ward, Jessica; Jarvis, Susan; Moretti, David; Morrissey, Ronald; Dimarzio, Nancy; Johnson, Mark; Tyack, Peter; Thomas, Len; Marques, Tiago
2011-02-01
Passive acoustic detection is being increasingly used to monitor visually cryptic cetaceans such as Blainville's beaked whales (Mesoplodon densirostris) that may be especially sensitive to underwater sound. The efficacy of passive acoustic detection is traditionally characterized by the probability of detecting the animal's sound emissions as a function of signal-to-noise ratio. The probability of detection can be predicted using accepted, but not necessarily accurate, models of the underwater acoustic environment. Recent field studies combining far-field hydrophone arrays with on-animal acoustic recording tags have yielded the location and time of each sound emission from tagged animals, enabling in-situ measurements of the probability of detection. However, tagging studies can only take place in calm seas and so do not reflect the full range of ambient noise conditions under which passive acoustic detection may be used. Increased surface-generated noise from wind and wave interaction degrades the signal-to-noise ratio of animal sound receptions at a given distance leading to a reduction in probability of detection. This paper presents a case study simulating the effect of increasing ambient noise on detection of M. densirostris foraging clicks recorded from a tagged whale swimming in the vicinity of a deep-water, bottom-mounted hydrophone array.
17. Acoustic temperature measurement in a rocket noise field.
Giraud, Jarom H; Gee, Kent L; Ellsworth, John E
2010-05-01
A 1 μm diameter platinum wire resistance thermometer has been used to measure temperature fluctuations generated during a static GEM-60 rocket motor test. Exact and small-signal relationships between acoustic pressure and acoustic temperature are derived in order to compare the temperature probe output with that of a 3.18 mm diameter condenser microphone. After preliminary plane wave tests yielded good agreement between the transducers within the temperature probe's ∼2 kHz bandwidth, comparison between the temperature probe and microphone data during the motor firing show that the ±∼3 K acoustic temperature fluctuations are a significant contributor to the total temperature variations.
18. Evaluation of Neural Networks Performance in Active Cancellation of Acoustic Noise
2014-12-01
Full Text Available Active Noise Control (ANC works on the principle of destructive interference between the primary disturbance field heard as undesired noise and the secondary field which is generated from control actuators. In the simplest system, the disturbance field can be a simple sine wave, and the secondary field is the same sine wave but 180 degrees out of phase. This research presents an investigation on the use of different types of neural networks in active noise control. Performance of the multilayer perceptron (MLP, Elman and generalized regression neural networks (GRNN in active cancellation of acoustic noise signals is investigated and compared in this paper. Acoustic noise signals are selected from a Signal Processing Information Base (SPIB database. In order to compare the networks appropriately, similar structures and similar training and test samples are deduced for neural networks. The simulation results show that MLP, GRNN, and Elman neural networks present proper performance in active cancellation of acoustic noise. It is concluded that Elman and MLP neural networks have better performance than GRNN in noise attenuation. It is demonstrated that designed ANC system achieve good noise reduction in low frequencies.
19. Phase-Sensitive Noise Suppression in a Photoacoustic Sensor based on Acoustic Circular Membrane Modes
Lassen, Mikael; Balslev-Harder, David; Petersen, Jan C
2014-01-01
A photoacoustic (PA) sensor based on higher order acoustic modes is demonstrated. The PA sensor is designed to enhance the gas-detection performance and simultaneously suppress ambient noise sources (e.g. flow noise, electrical noise and external acoustic noise). Two microphones are used and positioned such that the PA signals are ($\\pi$) out of phase. Ambient acoustic noise are approximately in the same phase and will be subtracted and thus improve the SNR. In addition, by placing the gas in- and outlets so that the gas flows through the node of the first higher order membrane mode the coupling of flow noise is approximately 20 dB lower compared with flow through the fundamental mode at 5 L/min. The noise reduction and thus the increase in sensitivity is demonstrated by measuring vibrational lines of methanol and methane using a broadband interband cascade laser emitting radiation at 3.38 $\\mu$m. A signal-to-noise improvement of 20 (26 dB) using higher order modes are demonstrated compared with the fundament...
20. Embedded Acoustic Sensor Array for Engine Fan Noise Source Diagnostic Test: Feasibility of Noise Telemetry via Wireless Smart Sensors
Zaman, Afroz; Bauch, Matthew; Raible, Daniel
2011-01-01
Aircraft engines have evolved into a highly complex system to meet ever-increasing demands. The evolution of engine technologies has primarily been driven by fuel efficiency, reliability, as well as engine noise concerns. One of the sources of engine noise is pressure fluctuations that are induced on the stator vanes. These local pressure fluctuations, once produced, propagate and coalesce with the pressure waves originating elsewhere on the stator to form a spinning pressure pattern. Depending on the duct geometry, air flow, and frequency of fluctuations, these spinning pressure patterns are self-sustaining and result in noise which eventually radiate to the far-field from engine. To investigate the nature of vane pressure fluctuations and the resulting engine noise, unsteady pressure signatures from an array of embedded acoustic sensors are recorded as a part of vane noise source diagnostics. Output time signatures from these sensors are routed to a control and data processing station adding complexity to the system and cable loss to the measured signal. "Smart" wireless sensors have data processing capability at the sensor locations which further increases the potential of wireless sensors. Smart sensors can process measured data locally and transmit only the important information through wireless communication. The aim of this wireless noise telemetry task was to demonstrate a single acoustic sensor wireless link for unsteady pressure measurement, and thus, establish the feasibility of distributed smart sensors scheme for aircraft engine vane surface unsteady pressure data transmission and characterization.
1. Ambient Noise Surface Wave Tomography for Geotechnical Monitoring Using "Large N" Distributed Acoustic Sensing
Ajo Franklin, J. B.; Lindsey, N.; Martin, E. R.; Wagner, A. M.; Robertson, M.; Bjella, K.; Gelvin, A.; Ulrich, C.; Wu, Y.; Freifeld, B. M.; Daley, T. M.; Dou, S.
2015-12-01
Surface wave tomography using ambient noise sources has found broad application at the regional scale but has not been adopted fully for geotechnical applications despite the abundance of noise sources in this context. The recent development of Distributed Acoustic Sensing (DAS) provides a clear path for inexpensively recording high spatial resolution (survey as well as direct-push data on ice content. We also compare vintages of ambient noise DAS data to evaluate the short-term repeatability of the technique in the face of changing noise environments. The resulting dataset demonstrates the utility of using DAS for real-time shear-modulus monitoring in support of critical infrastructure.
2. Noise Impact and Improvement on Indoors Acoustic Comfort for the Building Adjacent to Heavy Traffic Road
Li Zhisheng; Li Dongmei; Mei Sheng; Zhang Guoqiang; Liu Jianlong
2007-01-01
3. Intelligent background noise reduction technology in cable fault locator using the magneto-acoustic synchronous method
Mi, JianWei; Huang, JiFa; Fang, XiaoLi; Fan, LiBin
2017-01-01
The magneto-acoustic synchronous method has found wide application in accurate positioning of power cable fault due to its advantages of high accuracy and strong ability to reject interference. In the view of principle, the magneto-acoustic synchronous method needs to detect the discharge sound signal and electromagnetic signal emitted from the fault point, but the discharge sound signal is easy to be interfered by the ambient noise around and the magnetic sound synchronization. Therefore, it is challenging to quickly and accurately detect the fault location of cable especially in strong background noise environment. On the other hand, the spectral subtraction is a relatively traditional and effective method in many intelligent background noise reduction technologies, which is characterized by a relatively small computational cost and strong real-time performance. However, its application is limited because the algorithm displays poor performance in low Signal to Noise Ratio (SNR) environment. Aiming at the shortcoming of the spectral subtraction that de-noising effect is weak in low SNR environment, this paper proposes an improved spectral subtraction combining the magnetic sound synchronous principle and analyzing the properties of discharging sound. This method can accurately estimate noise in real time and optimize the performance of the basic spectral subtraction thus solving the problem that the magneto-acoustic synchronous method is unsatisfactory for positioning cable fault in the strong background noise environment.
4. Extraction and application of the low dimensional dynamical component from underwater acoustic target radiating noise
LIANG Juan; LU Jiren
2001-01-01
Signal processing in phase space based on nonlinear dynamics theory is a new method for underwater acoustic signal processing. One key problem when analyzing actual acoustic signal in phase space is how to reduce the noise and lower the embedding dimension. In this paper, local-geometric-projection method is applied to obtain low dimensional element from various target radiating noise and the derived phase portraits show obviously low dimensional attractors. Furthermore, attractor dimension and cross prediction error are used for classification. It concludes that combining these features representing the geometric and dynamical properties respectively shows effects in target classification.
5. Structural and acoustic noise radiated by CD drives
Nijhof, Marten J.J.; Beltman, Willem M.
2005-01-01
Optical drives inside PCs operate at high speed, which may result in significant noise. These drives function both as airborne and structural vibration sources. Three main paths can be distinguished through which noise is emitted to the surroundings: (1) the vibrations of the front of the drive emit
6. Acoustical topology optimization for Zwicker's loudness model - Application to noise barriers
Kook, Junghwan; Koo, Kunmo; Hyun, Jaeyub;
2012-01-01
Traditionally, the objective of design optimization of an acoustic system is to reduce physical acoustic properties, i.e., sound pressure and power. However, since these parameters are not sufficient to present the relation of physical sound stimulus with human perceptual judgment, physical...... acoustic properties may not represent adequate parameters for optimizing acoustic devices. In this paper, we first present a design method for acoustical topology optimization by considering human's subjective conception of sound. To consider human hearing characteristics. Zwicker's loudness is calculated...... the finite element method. The sensitivity of the main specific loudness is calculated using the adjoint variable method and the chain rule. To demonstrate the effectiveness of the proposed method, various examples of noise barriers are presented with different source and receiver locations. The results...
7. Towards a Comprehensive Model of Jet Noise Using an Acoustic Analogy and Steady RANS Solutions
Miller, Steven A. E.
2013-01-01
An acoustic analogy is developed to predict the noise from jet flows. It contains two source models that independently predict the noise from turbulence and shock wave shear layer interactions. The acoustic analogy is based on the Euler equations and separates the sources from propagation. Propagation effects are taken into account by calculating the vector Green's function of the linearized Euler equations. The sources are modeled following the work of Tam and Auriault, Morris and Boluriaan, and Morris and Miller. A statistical model of the two-point cross-correlation of the velocity fluctuations is used to describe the turbulence. The acoustic analogy attempts to take into account the correct scaling of the sources for a wide range of nozzle pressure and temperature ratios. It does not make assumptions regarding fine- or large-scale turbulent noise sources, self- or shear-noise, or convective amplification. The acoustic analogy is partially informed by three-dimensional steady Reynolds-Averaged Navier-Stokes solutions that include the nozzle geometry. The predictions are compared with experiments of jets operating subsonically through supersonically and at unheated and heated temperatures. Predictions generally capture the scaling of both mixing noise and BBSAN for the conditions examined, but some discrepancies remain that are due to the accuracy of the steady RANS turbulence model closure, the equivalent sources, and the use of a simplified vector Green's function solver of the linearized Euler equations.
8. High levels of sound pressure: acoustic reflex thresholds and auditory complaints of workers with noise exposure
Alexandre Scalli Mathias Duarte
2015-08-01
Full Text Available INTRODUCTION: The clinical evaluation of subjects with occupational noise exposure has been difficult due to the discrepancy between auditory complaints and auditory test results. This study aimed to evaluate the contralateral acoustic reflex thresholds of workers exposed to high levels of noise, and to compare these results to the subjects' auditory complaints.METHODS: This clinical retrospective study evaluated 364 workers between 1998 and 2005; their contralateral acoustic reflexes were compared to auditory complaints, age, and noise exposure time by chi-squared, Fisher's, and Spearman's tests.RESULTS: The workers' age ranged from 18 to 50 years (mean = 39.6, and noise exposure time from one to 38 years (mean = 17.3. We found that 15.1% (55 of the workers had bilateral hearing loss, 38.5% (140 had bilateral tinnitus, 52.8% (192 had abnormal sensitivity to loud sounds, and 47.2% (172 had speech recognition impairment. The variables hearing loss, speech recognition impairment, tinnitus, age group, and noise exposure time did not show relationship with acoustic reflex thresholds; however, all complaints demonstrated a statistically significant relationship with Metz recruitment at 3000 and 4000 Hz bilaterally.CONCLUSION: There was no significance relationship between auditory complaints and acoustic reflexes.
9. Flow-induced noise simulation using detached eddy simulation and the finite element acoustic analogy method
Kai Liu
2016-06-01
Full Text Available Signals in long-distance pipes are complex due to flow-induced noise generated in special structure, and the computation of these noise sources is difficult and time-consuming. To address this problem, a hybrid method based on computational fluid dynamics and Lighthill’s acoustic analogy theory is proposed to simulate flow-induced noise, with the results showing that the method is sufficient for noise predictions. The proposed method computes the turbulent flow field using detached eddy simulation and then calculates turbulence-generated sound using the finite element acoustic analogy method, which solves acoustic sources as volume sources. The velocity field obtained in the detached eddy simulation computation provides the sound source through interpolation between the computational fluid dynamics and acoustic meshes. The hybrid method is validated and assessed by comparing data from the cavity in pipe and large eddy simulation results. The peak value of flow-induced noise calculated at the monitor point is in good agreement with experimental data available in the literature.
10. A New Probe Noise Approach For Acoustic Feedback Cancellation In Hearing Aids
Guo, Meng; Jensen, Søren Holdt; Jensen, Jesper
Acoustic feedback is a big challenge in hearing aids. If not appropriately treated, the feedback limits the maximum possible amplification and may lead to significant sound distortions. In a state-of-the-art hearing aid, an acoustic feedback cancellation (AFC) system is used to compensate...... systems is the biased adaptive filter estimation problem, especially when tonal signals such as music and alarm tones enter the hearing aid microphones. The consequences of this biased estimation might be significant sound distortion or even worse, howling. In principle, unbiased adaptive filter...... estimation can be achieved by adding a probe noise signal to the receiver signal and basing the estimation on the probe noise signal. However, the traditional probe noise approach requires a high-level probe noise signal, which is clearly audible and annoying for the hearing aid user. Hence, this high probe...
11. Acoustic Noise of MRI Scans of the Internal Auditory Canal and Potential for Intracochlear Physiological Changes
Busada, M A; Ibrahim, G; Huckans, J H
2012-01-01
Magnetic resonance imaging (MRI) is a widely used medical imaging technique to assess the health of the auditory (vestibulocochlear) nerve. A well known problem with MRI machines is that the acoustic noise they generate during a scan can cause auditory temporary threshold shifts (TTS) in humans. In addition, studies have shown that excessive noise in general can cause rapid physiological changes of constituents of the auditory within the cochlea. Here, we report in-situ measurements of the acoustic noise from a 1.5 Tesla MRI machine (GE Signa) during scans specific to auditory nerve assessment. The measured average and maximum noise levels corroborate earlier investigations where TTS occurred. We briefly discuss the potential for physiological changes to the intracochlear branches of the auditory nerve as well as iatrogenic misdiagnoses of intralabyrinthine and intracochlear schwannomas due to hypertrophe of the auditory nerve within the cochlea during MRI assessment.
12. Local-linear-prediction analysis for underwater acoustic target radiated noise
LIANG Juan; LU Jiren
2002-01-01
Local-linear-prediction in phase space is performed for the underwater acoustic target radiated noise. Relation curve of average prediction error versus neighboring points' number is calculated. The result is used in judging the nonlinearity of radiated noise time series, and obtaining the appropriate form and coefficients of predicting model. The line and continuous spectral component are predicted respectively. Choice of some model parameters minimizing the prediction error is also discussed.
13. Energy-Based Acoustic Measurement System for Rocket Noise Project
National Aeronautics and Space Administration — Accurate estimates of the vibroacoustic loading placed on space vehicles and payloads during launch require knowledge of the rocket noise source properties. Given...
14. Initial Integration of Noise Prediction Tools for Acoustic Scattering Effects
Nark, Douglas M.; Burley, Casey L.; Tinetti, Ana; Rawls, John W.
2008-01-01
This effort provides an initial glimpse at NASA capabilities available in predicting the scattering of fan noise from a non-conventional aircraft configuration. The Aircraft NOise Prediction Program, Fast Scattering Code, and the Rotorcraft Noise Model were coupled to provide increased fidelity models of scattering effects on engine fan noise sources. The integration of these codes led to the identification of several keys issues entailed in applying such multi-fidelity approaches. In particular, for prediction at noise certification points, the inclusion of distributed sources leads to complications with the source semi-sphere approach. Computational resource requirements limit the use of the higher fidelity scattering code to predict radiated sound pressure levels for full scale configurations at relevant frequencies. And, the ability to more accurately represent complex shielding surfaces in current lower fidelity models is necessary for general application to scattering predictions. This initial step in determining the potential benefits/costs of these new methods over the existing capabilities illustrates a number of the issues that must be addressed in the development of next generation aircraft system noise prediction tools.
15. Workers' exposure to noise inside complex acoustic environments in Canada : a qualitative analysis
Hertil, S. [Inst. of Noise Control Engineers, Calgary, AB (Canada)
2007-07-01
Occupational noise regulations in Canada have limits on the permissible exposure of a worker to noise in the workplace. These limits are set in terms of an 8-hour average sound level of 85 dBA, with limits of 135 dBC on peak sound pressure levels. However, these noise regulations do not specify any qualitative limits on noise levels and are not clear enough for providing adequate protection of workers against low-frequency noise and inaudible air vibrations and infrasound commonly found in heavy industrial sites and power generation plants. This paper presented actual sound level data that was collected at various power plants in Canada during the period 1995 - 2005. It was shown that noise in the work place includes inaudible low-frequency noise and air vibrations that are impossible to detect by dosimeters or type 1 and type 2 hand held sound level meters. The paper described exposure to noise inside a small, gas-fired generator hall; exposure to noise inside a large steam processing plant; exposure to noise in the area of roller ball mills; noise quality inside a steam processing plant; noise quality inside a coal ball mill building; noise quality inside a large water feed pump area; and quality of noise inside a steam turbine hall. The frequencies that are harmful to workers were identified in an effort to design noise control features for machinery or equipment and to develop abatement measures to protect workers operating in complex acoustic environments. It was concluded that noise control is a collective task that should be undertaken by many professionals from all the fields related to health, safety, hearing and hearing conservation. 3 refs., 2 tabs., 6 figs.
16. Robustness of intrinsic connectivity networks in the human brain to the presence of acoustic scanner noise
Langers, Dave R. M.; van Dijk, Pim
2011-01-01
Evoked responses in functional magnetic resonance imaging (fMRI) are affected by the presence of acoustic scanner noise (ASN). Particularly, stimulus-related activation of the auditory system and deactivation of the default mode network have repeatedly been shown to diminish. In contrast, little is
17. Wind Turbine Acoustic Investigation: Infrasound and Low-Frequency Noise--A Case Study
Ambrose, Stephen E.; Rand, Robert W.; Krogh, Carmen M. E.
2012-01-01
Wind turbines produce sound that is capable of disturbing local residents and is reported to cause annoyance, sleep disturbance, and other health-related impacts. An acoustical study was conducted to investigate the presence of infrasonic and low-frequency noise emissions from wind turbines located in Falmouth, Massachusetts, USA. During the…
18. A scalable acoustic sensor network for model based monitoring of urban traffic noise
Basten, T.G.H.; Wessels, P.W.; Eerden, F.J.M. van der
2012-01-01
A good understanding of the acoustic environment due to traffic in urban areas is very important. Long term monitoring within large areas provides a clear insight in the actual noise situation. This is needed to take appropriate and cost efficient measures; to asses the effect of measures by compari
19. Load influence on gear noise. [mathematical model for determining acoustic pressure level as function of load
Merticaru, V.
1974-01-01
An original mathematical model is proposed to derive equations for calculation of gear noise. These equations permit the acoustic pressure level to be determined as a function of load. Application of this method to three parallel gears is reported. The logical calculation scheme is given, as well as the results obtained.
20. A measure of acoustic noise generated from transcranial magnetic stimulation coils.
Dhamne, Sameer C; Kothare, Raveena S; Yu, Camilla; Hsieh, Tsung-Hsun; Anastasio, Elana M; Oberman, Lindsay; Pascual-Leone, Alvaro; Rotenberg, Alexander
2014-01-01
The intensity of sound emanating from the discharge of magnetic coils used in repetitive transcranial magnetic stimulation (rTMS) can potentially cause acoustic trauma. Per Occupational Safety and Health Administration (OSHA) standards for safety of noise exposure, hearing protection is recommended beyond restricted levels of noise and time limits. We measured the sound pressure levels (SPLs) from four rTMS coils with the goal of assessing if the acoustic artifact levels are of sufficient amplitude to warrant protection from acoustic trauma per OSHA standards. We studied the SPLs at two frequencies (5 and 10 Hz), three machine outputs (MO) (60, 80 and 100%), and two distances from the coil (5 and 10 cm). We found that the SPLs were louder at closer proximity from the coil and directly dependent on the MO. We also found that in all studied conditions, SPLs were lower than the OSHA permissible thresholds for short (8 h) exposure.
1. Adaptive Noise Reduction Techniques for Airborne Acoustic Sensors
2012-01-01
25 4.3 Super Kraft Monocoupe 90A RC airplane. . . . . . . . . . . . . . . . . . . . . . . 27 4.4 Access panel for fuselage of...begin clipping. This is an important consideration for airborne acoustic sensing, as the sound level aboard a UAV must not cause saturation of the...specifications of the Monocoupe used for this experiment are in Table 4.3. 26 Figure 4.3: Super Kraft Monocoupe 90A RC airplane. Figure 4.4: Access panel for
2. A novel full scale experimental characterization of wind turbine aero-acoustic noise sources - preliminary results
Aagaard Madsen, Helge; Bertagnolio, Franck; Fischer, Andreas;
2016-01-01
The paper describes a novel full scale experiment on a 500 kW wind turbine with the main objective to characterize the aero-acoustic noise sources. The idea behind the instrumentation is to study the link and correlation between the surface pressure (SP) fluctuations in the boundary layer...... of the blade and the noise on the ground in a distance of about one rotor diameter. In total six surface microphones were used to measure the SP at the leading edge (LE) and trailing edge (TE) of the blade. In parallel noise was measured by eight microphones placed on plates on the ground around the turbine...
3. Effects of noise and acoustics in schools on vocal health in teachers.
Cutiva, Lady Catherine Cantor; Burdorf, Alex
2015-01-01
Previous studies on the influence of noise and acoustics in the classroom on voice symptoms among teachers have exclusively relied on self-reports. Since self-reported physical conditions may be biased, it is important to determine the role of objective measurements of noise and acoustics in the presence of voice symptoms. To assess the association between objectively measured and self-reported physical conditions at school with the presence of voice symptoms among teachers. In 12 public schools in Bogotα, we conducted a cross-sectional study among 682 Colombian school workers at 377 workplaces. After signed the informed consent, participants filled out a questionnaire on individual and work-related conditions and the nature and severity of voice symptoms in the past month. Short-term environmental measurements of sound levels, temperature, humidity, and reverberation time were conducted during visits at the workplaces, such as classrooms and offices. Logistic regression analysis was used to determine associations between work-related factors and voice symptoms. High noise levels outside schools (odds ratio [OR] = 1.83; 95% confidence interval [CI]: 1.12-2.99) and self-reported poor acoustics at the workplace (OR = 2.44; 95% CI: 1.88-3.53) were associated with voice symptoms. We found poor agreement between the objective measurements and self-reports of physical conditions at the workplace. This study indicates that noise and acoustics may play a role in the occurrence of voice symptoms among teachers. The poor agreement between objective measurements and self-reports of physical conditions indicate that these are different entities, which argue for inclusion of physical measurements of the working environment in studies on the influence of noise and acoustics on vocal health.
4. The Prediction of Jet Noise Ground Effects Using an Acoustic Analogy and a Tailored Green's Function
Miller, Steven A. E.
2013-01-01
An assessment of an acoustic analogy for the mixing noise component of jet noise in the presence of an infinite surface is presented. The reflection of jet noise by the ground changes the distribution of acoustic energy and is characterized by constructive and destructive interference patterns. The equivalent sources are modeled based on the two-point cross- correlation of the turbulent velocity fluctuations and a steady Reynolds-Averaged Navier-Stokes (RANS) solution. Propagation effects, due to reflection by the surface and refaction by the jet shear layer, are taken into account by calculating the vector Green's function of the linearized Euler equations (LEE). The vector Green's function of the LEE is written in relation to Lilley's equation; that is, approximated with matched asymptotic solutions and the Green's function of the convective Helmholtz equation. The Green's function of the convective Helmholtz equation for an infinite flat plane with impedance is the Weyl-van der Pol equation. Predictions are compared with an unheated Mach 0.95 jet produced by a nozzle with an exit diameter of 0.3302 meters. Microphones are placed at various heights and distances from the nozzle exit in the peak jet noise direction above an acoustically hard and an asphalt surface. The predictions are shown to accurately capture jet noise ground effects that are characterized by constructive and destructive interference patterns in the mid- and far-field and capture overall trends in the near-field.
5. A simulation study of harmonics regeneration in noise reduction for electric and acoustic stimulation.
Hu, Yi
2010-05-01
Recent research results show that combined electric and acoustic stimulation (EAS) significantly improves speech recognition in noise, and it is generally established that access to the improved F0 representation of target speech, along with the glimpse cues, provide the EAS benefits. Under noisy listening conditions, noise signals degrade these important cues by introducing undesired temporal-frequency components and corrupting harmonics structure. In this study, the potential of combining noise reduction and harmonics regeneration techniques was investigated to further improve speech intelligibility in noise by providing improved beneficial cues for EAS. Three hypotheses were tested: (1) noise reduction methods can improve speech intelligibility in noise for EAS; (2) harmonics regeneration after noise reduction can further improve speech intelligibility in noise for EAS; and (3) harmonics sideband constraints in frequency domain (or equivalently, amplitude modulation in temporal domain), even deterministic ones, can provide additional benefits. Test results demonstrate that combining noise reduction and harmonics regeneration can significantly improve speech recognition in noise for EAS, and it is also beneficial to preserve the harmonics sidebands under adverse listening conditions. This finding warrants further work into the development of algorithms that regenerate harmonics and the related sidebands for EAS processing under noisy conditions.
6. Intensity of noise in the classroom and analysis of acoustic emissions in schoolchildren
Almeida Filho, Nelson de
2012-01-01
Full Text Available Introduction: Noise-induced hearing loss is a sensorineural hearing loss, usually bilateral, irreversible and progressive with time of exposure. As the noise made by children in school may be considered detrimental, the study looks of their occurrence in Taubaté's schools. Objective: To determine if students are exposed to noise intensity affecting the cochlea, define the profile of these schoolchildren, demonstrating the occurrence of changes in cochlear activity following exposure to noise in a day of class. Method: Study's way prospective transversal cross sectional cut with 28 elementary school students in the first half of 2009. Questionnaires for assessing preexisting cochlear damage . Evaluation of cochlear function by analysis of acoustic emissions evoked distortion product, made before the students come into class and immediately after the end of these. Measurement of noise inside the classrooms and recreation areas during the interval. Results: 57.1% accused some hearing loss in the examinations before class. By day's end, 04 girls and 03 boys had worsened in relation of the first examination. The noise reached levels higher than recommended at the three class rooms. The largest number of students with worsening, belong to the class room with higher noise level. The noise during the intervals is also excessive. Conclusions: The noise in this school is above the limit. 42.85% of students who had experienced worsening had school performance inadequate. 25% had worse after noise exposure in a school day.
7. Characterizing noise in nonhuman vocalizations: Acoustic analysis and human perception of barks by coyotes and dogs
Riede, Tobias; Mitchell, Brian R.; Tokuda, Isao; Owren, Michael J.
2005-07-01
Measuring noise as a component of mammalian vocalizations is of interest because of its potential relevance to the communicative function. However, methods for characterizing and quantifying noise are less well established than methods applicable to harmonically structured aspects of signals. Using barks of coyotes and domestic dogs, we compared six acoustic measures and studied how they are related to human perception of noisiness. Measures of harmonic-to-noise-ratio (HNR), percent voicing, and shimmer were found to be the best predictors of perceptual rating by human listeners. Both acoustics and perception indicated that noisiness was similar across coyote and dog barks, but within each species there was significant variation among the individual vocalizers. The advantages and disadvantages of the various measures are discussed.
8. Improved jet noise modeling using a new acoustic time scale
Azarpeyvand, M.; Self, R.H.; Golliard, J.
2006-01-01
To calculate the noise emanating from a turbulent flow (such as a jet flow) using Lighthill's analogy, knowledge concerning the unsteady characteristics of the turbulence is required. Specifically, the form of the turbulent correlation tensor together with various time and length-scales and convecti
9. Hunting at the highway: traffic noise reduces foraging efficiency in acoustic predators.
Siemers, Björn M; Schaub, Andrea
2011-06-07
Noise pollution from human traffic networks and industrial activity impacts vast areas of our planet. While anthropogenic noise effects on animal communication are well documented, we have very limited understanding of noise impact on more complex ecosystem processes, such as predator-prey interactions, albeit urgently needed to devise mitigation measures. Here, we show that traffic noise decreases the foraging efficiency of an acoustic predator, the greater mouse-eared bat (Myotis myotis). These bats feed on large, ground-running arthropods that they find by listening to their faint rustling sounds. We measured the bats' foraging performance on a continuous scale of acoustically simulated highway distances in a behavioural experiment, designed to rule out confounding factors such as general noise avoidance. Successful foraging bouts decreased and search time drastically increased with proximity to the highway. At 7.5 m to the road, search time was increased by a factor of five. From this increase, we predict a 25-fold decrease in surveyed ground area and thus in foraging efficiency for a wild bat. As most of the bats' prey are predators themselves, the noise impact on the bats' foraging performance will have complex effects on the food web and ultimately on the ecosystem stability. Similar scenarios apply to other ecologically important and highly protected acoustic predators, e.g. owls. Our study provides the empirical basis for quantitative predictions of anthropogenic noise impacts on ecosystem processes. It highlights that an understanding of the effects of noise emissions and other forms of 'sensory pollution' are crucially important for the assessment of environmental impact of human activities.
10. Noise reduction of a composite cylinder subjected to random acoustic excitation
Grosveld, Ferdinand W.; Beyer, T.
1989-01-01
Interior and exterior noise measurements were conducted on a stiffened composite floor-equipped cylinder, with and without an interior trim installed. Noise reduction was obtained for the case of random acoustic excitation in a diffuse field; the frequency range of interest was 100-800-Hz one-third octave bands. The measured data were compared with noise reduction predictions from the Propeller Aircraft Interior Noise (PAIN) program and from a statistical energy analysis. Structural model parameters were not predicted well by the PAIN program for the given input parameters; this resulted in incorrect noise reduction predictions for the lower one-third octave bands where the power flow into the interior of the cylinder was predicted on a mode-per-mode basis.
11. Acoustic theory of axisymmetric multisectioned ducts. [reduction of turbofan engine noise
Zorumski, W. E.
1974-01-01
Equations are developed for the acoustic field in a duct system which is made up of a number of connected circular and annular ducts. These equations are suitable for finding the acoustic field inside of and radiated from an aircraft turbofan engine. Acoustic modes are used as generalized coordinates in order to develop a set of matrix equations for the acoustic field. Equations for these modes are given for circular and annular ducts with uniform flow. Modal source equations are derived for point acoustic sources. General equations for mode transmission and reflection are developed and detailed equations are derived for ducts with multiple sections of acoustic treatment and for ducts with circumferential splitter rings. The general theory is applied to the special case of a uniform area circular duct with multisection liners and it is shown that the mode reflection effects are proportional to differences of the acoustic admittances of adjacent liners. A numerical example is given which shows that multisection liners may provide greater noise suppression than uniform liners.
12. The ecological and evolutionary consequences of noise-induced acoustic habitat loss
Tennessen, Jennifer Beissinger
Anthropogenic threats are facilitating rapid environmental change and exerting novel pressures on the integrity of ecological patterns and processes. Currently, habitat loss is the leading factor contributing to global biodiversity loss. Noise created by human activities is nearly ubiquitous in terrestrial and marine systems, and causes acoustic habitat loss by interfering with species' abilities to freely send and receive critical acoustic biological information. My dissertation investigates how novel sounds from human activities affect ecological and evolutionary processes in space and time in marine and terrestrial systems, and how species may cope with this emerging novel pressure. Using species from both marine and terrestrial systems, I present results from a theoretical investigation, and four acoustic playback experiments combining laboratory studies and field trials, that reveal a range of eco-evolutionary consequences of noiseinduced acoustic habitat loss. First, I use sound propagation modeling to assess how marine shipping noise reduces communication space between mother-calf pairs of North Atlantic right whales (Eubalaena glacialis ), an important unit of an endangered species. I show that shipping noise poses significant challenges for mother-calf pairs, but that vocal compensation strategies can substantially improve communication space. Next, in a series of acoustic playback experiments I show that road traffic noise impairs breeding migration behavior and physiology of wood frogs (Lithobates sylvaticus ). This work reveals the first evidence that traffic noise elicits a physiological stress response and suppresses production of antimicrobial peptides (a component of the innate immune response) in anurans. Further, wood frogs from populations with a history of inhabiting noisy sites mounted reduced physiological stress responses to continuous traffic noise exposure. This research using wood frogs suggests that chronic traffic noise exposure has
13. Ocean acoustic remote sensing using ambient noise: results from the Florida Straits
Brown, M. G.; Godin, O. A.; Zang, X.; Ball, J. S.; Zabotin, N. A.; Zabotina, L. Y.; Williams, N. J.
2016-07-01
Noise interferometry is the process by which approximations to acoustic Green's functions, which describe sound propagation between two locations, are estimated by cross-correlating time series of ambient noise measured at those locations. Noise-interferometry-based approximations to Green's functions can be used as the basis for a variety of inversion algorithms, thereby providing a purely passive alternative to active-source ocean acoustic remote sensing. In this paper we give an overview of results from noise interferometry experiments conducted in the Florida Straits at 100 m depth in December 2012, and at 600 m depth in September/October 2013. Under good conditions for noise interferometry, estimates of cross-correlation functions are shown to allow one to perform advanced phase-coherent signal processing techniques to perform waveform inversions, estimate currents by exploiting non-reciprocity, perform time-reversal/back-propagation calculations and investigate modal dispersion using time-warping techniques. Conditions which are favourable for noise interferometry are identified and discussed.
14. Novel Acoustic Feedback Cancellation Approaches In Hearing Aid Applications Using Probe Noise and Probe Noise Enhancement
Guo, Meng; Jensen, Søren Holdt; Jensen, Jesper
2012-01-01
Adaptive filters are widely used in acoustic feedback cancellation systems and have evolved to be state-of-the-art. One major challenge remaining is that the adaptive filter estimates are biased due to the nonzero correlation between the loudspeaker signals and the signals entering the audio syst...... the proposed approaches much more attractive in practical applications. We demonstrate this through a simulation experiment with audio signals in a hearing aid acoustic feedback cancellation system, where the convergence rate is improved by as much as a factor of 10....
15. Noise Reduction Evaluation of Multi-Layered Viscoelastic Infinite Cylinder under Acoustical Wave Excitation
M.R. Mofakhami
2008-01-01
Full Text Available In this paper sound transmission through the multilayered viscoelastic air filled cylinders subjected to the incident acoustic wave is studied using the technique of separation of variables on the basis of linear three dimensional theory of elasticity. The effect of interior acoustic medium on the mode maps (frequency vs geometry and noise reduction is investigated. The effects of internal absorption and external moving medium on noise reduction are also evaluated. The dynamic viscoelastic properties of the structure are rigorously taken into account with a power law technique that models the viscoelastic damping of the cylinder. A parametric study is also performed for the two layered infinite cylinders to obtain the effect of viscoelastic layer characteristics such as thickness, material type and frequency dependency of viscoelastic properties on the noise reduction. It is shown that using constant and frequency dependent viscoelastic material with high loss factor leads to the uniform noise reduction in the frequency domain. It is also shown that the noise reduction obtained for constant viscoelastic material property is subjected to some errors in the low frequency range with respect to those obtained for the frequency dependent viscoelastic material.
16. Odeon, a design tool for auditorium acoustics, noise control and loudspeaker systems
Christensen, Claus Lynge
2001-01-01
The ODEON software was originally developed for prediction of auditorium acoustics. However current editions of the software are not limited to these fields, but also allow prediction in rooms such as churches and mosques, interior noise control, design of room acoustics and sound distribution...... systems in public rooms such as foyers, underground stations and airports. Some of the features in ODEON 5.0 Combined are; two methods for global estimation of reverberation time, various point response calculations providing decay curves, reflectograms, miscellaneous parameter graphs, 3D maps, multi......-source calculations including point, line and surface sources, facilities for noise control calculations and multi-channel auralization using fully filtered BRIR’s....
17. Robust Distributed Noise Reduction in Hearing Aids with External Acoustic Sensor Nodes
Marc Moonen
2009-01-01
Full Text Available The benefit of using external acoustic sensor nodes for noise reduction in hearing aids is demonstrated in a simulated acoustic scenario with multiple sound sources. A distributed adaptive node-specific signal estimation (DANSE algorithm, that has a reduced communication bandwidth and computational load, is evaluated. Batch-mode simulations compare the noise reduction performance of a centralized multi-channel Wiener filter (MWF with DANSE. In the simulated scenario, DANSE is observed not to be able to achieve the same performance as its centralized MWF equivalent, although in theory both should generate the same set of filters. A modification to DANSE is proposed to increase its robustness, yielding smaller discrepancy between the performance of DANSE and the centralized MWF. Furthermore, the influence of several parameters such as the DFT size used for frequency domain processing and possible delays in the communication link between nodes is investigated.
18. Computational Aero-acoustics As a Tool For Turbo-machinery Noise Reduction
Dyson, Rodger W.
2003-01-01
This talk will provide an overview of the field of computational aero-acoustics and its use in fan noise prediction. After a brief history of computational fluid dynamics, some of the recent developments in computational aero-acoustics will be explored. Computational issues concerning sound wave production, propagation, and reflection in practical turbo-machinery applications will be discussed including: (a) High order/High Resolution Numerical Techniques. (b) High Resolution Boundary Conditions. [c] MIMD Parallel Computing. [d] Form of Governing Equations Useful for Simulations. In addition, the basic design of our Broadband Analysis Stator Simulator (BASS) code and its application to a 2 D rotor wake-stator interaction will be shown. An example of the noise produced by the wakes from a rotor impinging upon a stator cascade will be shown.
19. Theoretical vibro-acoustic modeling of acoustic noise transmission through aircraft windows
Aloufi, Badr; Behdinan, Kamran; Zu, Jean
2016-06-01
In this paper, a fully vibro-acoustic model for sound transmission across a multi-pane aircraft window is developed. The proposed model is efficiently applied for a set of window models to perform extensive theoretical parametric studies. The studied window configurations generally simulate the passenger window designs of modern aircraft classes which have an exterior multi-Plexiglas pane, an interior single acrylic glass pane and a dimmable glass ("smart" glass), all separated by thin air cavities. The sound transmission loss (STL) characteristics of three different models, triple-, quadruple- and quintuple-paned windows identical in size and surface density, are analyzed for improving the acoustic insulation performances. Typical results describing the influence of several system parameters, such as the thicknesses, number and spacing of the window panes, on the transmission loss are then investigated. In addition, a comparison study is carried out to evaluate the acoustic reduction capability of each window model. The STL results show that the higher frequencies sound transmission loss performance can be improved by increasing the number of window panels, however, the low frequency performance is decreased, particularly at the mass-spring resonances.
20. Cogging Torque and Acoustic Noise Reduction in High Torque BLDC Motors by Teeth Pairings
Lee, Sang Min [Halla Climate Control Co. (Korea, Republic of); Hwang, Sang Moon [Pusan National University (Korea, Republic of)
1999-03-01
This paper investigates reduction of acoustic noise and cogging torque in a BLDC motor with larger stator slot open width. Using energy method, cogging torque is analytically determined with airgap MMF function and airgap permeance function and confirmed by FEM analysis. It show that the cogging torque is firstly governed by N{sub L} G{sub NL} B{sub NL} with the fundamental period of N{sub L}, where N{sub L} is the least common multiple of the number of slots and the number of poles, G{sub NL}, airgap permeance function and B{sub NL}, airgap MMF function. It also shows that there exist several tooth width which minimizes the cogging torque, for the motors that smaller slot open width or stator teeth notching is not available. And it proposes a teeth pairing with two different tooth width which can effectively eliminate the cogging torque and thus the acoustic noise. Experimental results show that the proposed teeth pairing reduces the cogging torque by 85% and the acoustic noise by 3.1 dB. (author). 9 refs., 13 figs., 1 tab.
1. Acoustic Noise Alters Selective Attention Processes as Indicated by Direct Current (DC Brain Potential Changes
Karin Trimmel
2014-09-01
2. Acoustic noise alters selective attention processes as indicated by direct current (DC) brain potential changes.
Trimmel, Karin; Schätzer, Julia; Trimmel, Michael
2014-09-26
3. Study on acoustical properties of sintered bronze porous material for transient exhaust noise of pneumatic system
Li, Jingxiang; Zhao, Shengdun; Ishihara, Kunihiko
2013-05-01
A novel approach is presented to study the acoustical properties of sintered bronze material, especially used to suppress the transient noise generated by the pneumatic exhaust of pneumatic friction clutch and brake (PFC/B) systems. The transient exhaust noise is impulsive and harmful due to the large sound pressure level (SPL) that has high-frequency. In this paper, the exhaust noise is related to the transient impulsive exhaust, which is described by a one-dimensional aerodynamic model combining with a pressure drop expression of the Ergun equation. A relation of flow parameters and sound source is set up. Additionally, the piston acoustic source approximation of sintered bronze silencer with cylindrical geometry is presented to predict SPL spectrum at a far-field observation point. A semi-phenomenological model is introduced to analyze the sound propagation and reduction in the sintered bronze materials assumed as an equivalent fluid with rigid frame. Experiment results under different initial cylinder pressures are shown to corroborate the validity of the proposed aerodynamic model. In addition, the calculated sound pressures according to the equivalent sound source are compared with the measured noise signals both in time-domain and frequency-domain. Influences of porosity of the sintered bronze material are also discussed.
4. Effect of scanner acoustic background noise on strict resting-state fMRI
C. Rondinoni
2013-04-01
Full Text Available Functional MRI (fMRI resting-state experiments are aimed at identifying brain networks that support basal brain function. Although most investigators consider a ‘resting-state' fMRI experiment with no specific external stimulation, subjects are unavoidably under heavy acoustic noise produced by the equipment. In the present study, we evaluated the influence of auditory input on the resting-state networks (RSNs. Twenty-two healthy subjects were scanned using two similar echo-planar imaging sequences in the same 3T MRI scanner: a default pulse sequence and a reduced “silent” pulse sequence. Experimental sessions consisted of two consecutive 7-min runs with noise conditions (default or silent counterbalanced across subjects. A self-organizing group independent component analysis was applied to fMRI data in order to recognize the RSNs. The insula, left middle frontal gyrus and right precentral and left inferior parietal lobules showed significant differences in the voxel-wise comparison between RSNs depending on noise condition. In the presence of low-level noise, these areas Granger-cause oscillations in RSNs with cognitive implications (dorsal attention and entorhinal, while during high noise acquisition, these connectivities are reduced or inverted. Applying low noise MR acquisitions in research may allow the detection of subtle differences of the RSNs, with implications in experimental planning for resting-state studies, data analysis, and ergonomic factors.
5. Active structural acoustic control of noise from power transformers; Aktive Laermdaemmung von Leistungstransformatoren mit Gegenlaerm
Brungardt, K.; Vierengel, J.; Weissmann, K. [Quiet Power Systems Inc., New York, NY (United States); Schemel, G.; Lorin, P. [ABB Secheron SA, Genf (Switzerland)
1998-04-06
Population growth and tougher zoning regulations mean transformer noise is a growing problem for electric utilities. Transformer noise is dominanted by low frequency tones which are difficult to control by passive means, but are effectively attenuated by active noise control. This paper details a novel noise control system that actively attenuates transformer noise using a combination of structural actuators mounted on the radiating surface of the transformer tank, and specially designed resonant acoustic devices located just off the tank surface. An adaptive selfcalibrating, multi-channel controller is used to automatically respond to changes in noise level during transformer operation. Performance results have been proven at a number of field installations in utility substations, and an installation case study is provided here as an example. (orig.) [Deutsch] Beim Betrieb von Leistungstransformatoren entstehen Geraeusche, die besonders in der Naehe von Wohngebieten als stoerend empfunden werden. Zunehmend strengere Laermschutzverordnungen erfordern daher Massnahmen um die Geraeuschentwicklung von Transformatoren zu reduzieren. Die passive Daempfung dieses Brummens durch Bauten ist oft mit hohen Kosten verbunden und bereitet Schwierigkeiten bei der Umsetzung. Fuer Abhilfe sorgt ein neuartiges System, das den Transformatorenlaerm aktiv daempft. Dabei setzt man zur Reduktion des Transformatorenlaerms neuartige, durch adaptive Algorythmen gesteuerte Aktuatoren ein, die den stoerenden Laerm direkt am Transformator selbst daempfen. (orig.)
6. Noise reduction in acoustic measurements with a particle velocity sensor by means of a cross-correlation technique
Honschoten, van J.W.; Druyvesteyn, W.F.; Kuipers, H.; Raangs, R.; Krijnen, G.J.M.
2004-01-01
In this paper a method is presented to reduce the noise level of a particle velocity sensor, a thermal two-wire sensor sensitive to acoustic particle velocities, which yields a reduction of the noise of 30 dB. The method is based on utilisation of cross- instead of auto-correlation spectra of two of
7. Validation of an Aero-Acoustic Wind Turbine Noise Model Using Advanced Noise Source Measurements of a 500kW Turbine
Bertagnolio, Franck; Aagaard Madsen, Helge; Fischer, Andreas
2016-01-01
The measurement of a 500 kW stall-regulated wind turbine is investigated. Microphones located relatively close to the wind turbine are used to measure its acoustic emission. The operational conditions of the turbine, such as wind speed, are simultaneously monitored. In parallel, a wind turbine....... A good qualitative agreement is found. When wind speed increases, the rotor noise model shows that at high frequencies the stall noise becomes dominant. It also shows that turbulent inflow noise is dominant at low frequencies for all wind speeds and that trailing edge noise is dominant at low wind speeds...... and at frequencies above 200 Hz....
8. Military jet noise source imaging using multisource statistically optimized near-field acoustical holography.
Wall, Alan T; Gee, Kent L; Neilsen, Tracianne B; McKinley, Richard L; James, Michael M
2016-04-01
The identification of acoustic sources is critical to targeted noise reduction efforts for jets on high-performance tactical aircraft. This paper describes the imaging of acoustic sources from a tactical jet using near-field acoustical holography techniques. The measurement consists of a series of scans over the hologram with a dense microphone array. Partial field decomposition methods are performed to generate coherent holograms. Numerical extrapolation of data beyond the measurement aperture mitigates artifacts near the aperture edges. A multisource equivalent wave model is used that includes the effects of the ground reflection on the measurement. Multisource statistically optimized near-field acoustical holography (M-SONAH) is used to reconstruct apparent source distributions between 20 and 1250 Hz at four engine powers. It is shown that M-SONAH produces accurate field reconstructions for both inward and outward propagation in the region spanned by the physical hologram measurement. Reconstructions across the set of engine powers and frequencies suggests that directivity depends mainly on estimated source location; sources farther downstream radiate at a higher angle relative to the inlet axis. At some frequencies and engine powers, reconstructed fields exhibit multiple radiation lobes originating from overlapped source regions, which is a phenomenon relatively recently reported for full-scale jets.
9. Effect of train type on annoyance and acoustic features of the rolling noise.
Kasess, Christian H; Noll, Anton; Majdak, Piotr; Waubke, Holger
2013-08-01
This study investigated the annoyance associated with the rolling noise of different railway stock. Passbys of nine train types (passenger and freight trains) equipped with different braking systems were recorded. Acoustic features showed a clear distinction of the braking system with the A-weighted energy equivalent sound level (LAeq) showing a difference in the range of 10 dB between cast-iron braked trains and trains with disk or K-block brakes. Further, annoyance was evaluated in a psychoacoustic experiment where listeners rated the relative annoyance of the rolling noise for the different train types. Stimuli with and without the original LAeq differences were tested. For the original LAeq differences, the braking system significantly affected the annoyance with cast-iron brakes being most annoying, most likely as a consequence of the increased wheel roughness causing an increased LAeq. Contribution of the acoustic features to the annoyance was investigated revealing that the LAeq explained up to 94% of the variance. For the stimuli without differences in the LAeq, cast-iron braked train types were significantly less annoying and the spectral features explained up to 60% of the variance in the annoyance. The effect of these spectral features on the annoyance of the rolling noise is discussed.
10. Usefulness of acoustic noise reduction in brain MRI using Quiet-T{sub 2}-
Lee, Se Jy [Dept. of Medical science Graduate school, Chonnam National University, Gwangju (Korea, Republic of); Kim, Young Keun [Dept. of Radiotechnology, Gwangju Health university, Gwangju (Korea, Republic of)
2016-03-15
Acoustic noise during magnetic resonance imaging (MRI) is the main source for patient discomfort. we report our preliminary experience with this technique in neuroimaging with regard to subjective and objective noise levels and image quality. 60 patients(29 males, 31 females, average age of 60.1) underwent routine brain MRI with 3.0 Tesla (MAGNETOM Tim Trio; Siemens, Germany) system and 12-channel head coil. Q-T{sub 2} and T{sub 2} sequence were performed. Measurement of sound pressure levels (SPL) and heart rate on Q-T{sub 2} and T{sub 2} was performed respectively. Quantitative analysis was carried out by measuring the SNR, CNR, and SIR values of Q-T{sub 2}, T{sub 2} and a statistical analysis was performed using independent sample T-test. Qualitative analysis was evaluated by the eyes for the overall quality image of Q-T{sub 2} and T{sub 2}. A 5-point evaluation scale was used, including excellent(5), good(4), fair(3), poor(2), and unacceptable(1). The average noise and peak noise decreased by 15dBA and 10dBA on T2 and Q-T2 test. Also, the average value of heartbeat rate was lower in Q-T2 for 120 seconds in each test, but there was no statistical significance. The quantitative analysis showed that there was no significant difference between CNR and SIR, and there was a significant difference (p<0.05) as SNR had a lower average value on Q-T{sub 2}. According to the qualitative analysis, the overall quality image of 59 case T{sub 2} and Q-T{sub 2} was evaluated as excellent at 5 points, and 1 case was evaluated as good at 4 points due to a motion artifact. Q-T{sub 2} is a promising technique for acoustic noise reduction and improved patient comfort.
11. Long term memory for noise: evidence of robust encoding of very short temporal acoustic patterns.
Jayalakshmi Viswanathan
2016-11-01
Full Text Available Recent research has demonstrated that humans are able to implicitly encode and retain repeating patterns in meaningless auditory noise. Our study aimed at testing the robustness of long-term implicit recognition memory for these learned patterns. Participants performed a cyclic/non-cyclic discrimination task, during which they were presented with either 1-s cyclic noises (CNs (the two halves of the noise were identical or 1-s plain random noises (Ns. Among CNs and Ns presented once, target CNs were implicitly presented multiple times within a block, and implicit recognition of these target CNs was tested 4 weeks later using a similar cyclic/non-cyclic discrimination task. Furthermore, robustness of implicit recognition memory was tested by presenting participants with looped (shifting the origin and scrambled (chopping sounds into 10- and 20-ms bits before shuffling versions of the target CNs. We found that participants had robust implicit recognition memory for learned noise patterns after 4 weeks, right from the first presentation. Additionally, this memory was remarkably resistant to acoustic transformations, such as looping and scrambling of the sounds. Finally, implicit recognition of sounds was dependent on participant’s discrimination performance during learning. Our findings suggest that meaningless temporal features as short as 10 ms can be implicitly stored in long-term auditory memory. Moreover, successful encoding and storage of such fine features may vary between participants, possibly depending on individual attention and auditory discrimination abilities.
12. Room acoustic analysis of blower unit and noise control plan in the typical steel industry
2013-02-01
Full Text Available Introduction: In the steel industry,air blowers used to supply compressed air are considered as sources of annoying noise. This study aims to acoustics analysis of theairblower workroomand sound source characteristics in order to present noise controlmeasuresinthe steel industry. .Material and Method: Measurement of noiselevel and its frequency analysis was performed usingsound levelmetermodelof CASELLA-Cell.450. Distribution of noise level in the investigated workroom in form of noise map was provided using Surfer software. In addition, acoustic analysis of workroom and control room was performed in view point of soundabsorption andinsulation. Redesignofdoor and window of controlroom and installation of soundabsorbing materialson theceiling of the workroom were proposed and the efficiency of these interventionswasestimated. .Result: The totalsound pressurelevelin the blower workroom was 95.4 dB(L and the dominant frequency was 2000Hz. Sound pressure level inside the room control was 80.1dB(A. The average absorption coefficient and reverberation time in the blower workroom was estimated equal to 0.082 Sab.m2 and 3.9 seconds respectively. These value in control room was 0.04 Sab.m2 and 3/4 seconds respectively. In control room, sound transmission loss between the two parts of the wall dividing was 13.7 dB(A. The average of noise dose in blower operators was 230%. With the installation of sound absorber on ceiling of workroom, average of absorption coefficient can increase to 0.33 Sab.m2 and sound transmission loss of the new designed door and window was estimated equal to 20dB. . Conclusion: The main cause of noise leakage in the control room was insufficient insulation properties of door and windows. By replacing the door and window and installation of sound absorbing on ceiling of workroom, the noise dose can reduce to 49.6%. New Improved door and window of control room can reduce noise dose to 69.65% solely.
13. Acoustics. Measurement of sound insulation in buildings and of building elements. Laboratory measurements of the reduction of transmitted impact noise by floor coverings on a heavyweight standard floor
British Standards Institution. London
1998-01-01
Acoustics. Measurement of sound insulation in buildings and of building elements. Laboratory measurements of the reduction of transmitted impact noise by floor coverings on a heavyweight standard floor
14. Effects of acoustic hood on noise, CFC-11, and particulate matter in a recycling system for waste refrigerator cabinet.
Guo, Jie; Fang, Wenxiong; Yang, Yichen; Xu, Zhenming
2014-11-01
The mechanical-physical process was proven to be technologically feasible for waste refrigerator recycling and has been widely used in the typical e-waste recycling factories in China. In this study, effects of the acoustic hood on the reduction of noise level, CFC-11, and heavy metals (Cr, Ni, Cu, Cd, and Pb) in particulate matter (PM) were evaluated. For noise pollution, the noise level inside and outside the acoustic hood was 96.4 and 78.9 dB, respectively. Meanwhile, it had a significant effect on A-weighted sound level with a reduction from 98.3 to 63.6 dB. For CFC-11 exposure, abundant CFC-11 (255 mg/m(3)) was detected in the acoustic hood. However, the mean concentration of CFC-11 at the outline of polyurethane foam collection was obviously diminished to 14 mg/m(3), and no CFC-11 was monitored around the acoustic hood. The concentrations of PM and heavy metals in PM outside the acoustic hood were lower than those inside the acoustic hood due to the physical barriers of the acoustic hood. Based on the risk assessment, only adverse health effect caused by Pb might likely appear. All the results can provide the basic data for pollution control and risk assessment in waste refrigerator recycling system.
15. Effects of Noise and Absorption on High Frequency Measurements of Acoustic-Backscatter from Fish
Masahiko Furusawa
2015-01-01
Full Text Available Quantitative echosounders operating at multiple frequencies (e.g., 18, 38, 70, 120, 200, 333, and 710 kHz are often used to observe fish and zooplankton and identify their species. At frequencies above 100 kHz, the absorption attenuation increases rapidly and decreases the signal-to-noise ratio (SNR. Also, incomplete compensation for the attenuation may result in measurement error. This paper addresses the effects of the attenuation and noise on high frequency measurements of acoustic backscatter from fish. It is shown that measurements of a fish with target strength of −40 dB at 200 m depth are limited by SNR to frequencies up to about 100 kHz. Above 100 kHz, absorption coefficients must be matched to local environmental conditions.
16. Implications for the thermal regime of acoustic noise measurements in Crater Lake, Mount Ruapehu, New Zealand
Vandemeulebrouck, J.; Hurst, A. W.; Poussielgue, N.
1994-12-01
Hydrophone measurements of acoustic noise levels in the Crater Lake of Mount Ruapehu, New Zealand were made on 18 January 1991 from an inflatable rubber boat on the lake. The greatest sound pressures were recorded in the 1 10 Hz band, with sound levels generally decreasing about 20 dB per decade from 10 Hz to 80 kHz. The low frequency noise did not have an obvious relationship to the tremor observed at a seismic station within 1 km of the lake. The comparatively low levels of middle and high frequency sound meant that at the time of measurement, direct steam input did not make a significant contribution to the heating of Crater Lake. This is consistent with the earlier conclusion that during the last decade a major part of the heat input of Crater Lake has come from lake water that was heated below the lake and recycled back into the lake.
17. Towards Truly Quiet MRI: animal MRI magnetic field gradients as a test platform for acoustic noise reduction
Edelstein, William; El-Sharkawy, Abdel-Monem
2013-03-01
Clinical MRI acoustic noise, often substantially exceeding 100 dB, causes patient anxiety and discomfort and interferes with functional MRI (fMRI) and interventional MRI. MRI acoustic noise reduction is a long-standing and difficult technical challenge. The noise is basically caused by large Lorentz forces on gradient windings--surrounding the patient bore--situated in strong magnetic fields (1.5 T, 3 T or higher). Pulsed currents of 300 A or more are switched through the gradient windings in sub-milliseconds. Experimenting with hardware noise reduction on clinical scanners is difficult and expensive because of the large scale and weight of clinical scanner components (gradient windings ~ 1000 kg) that require special handling equipment in large engineering test facilities. Our approach is to produce a Truly Quiet (test platform for acoustic noise reduction measures that can be implemented in clinical scanners. We have so far decreased noise in an animal scale imager from 108 dB to 71 dB, a 37 dB reduction. Our noise reduction measures include: a gradient container that can be evacuated; inflatable antivibration mounts to prevent transmission of vibrations from gradient winding to gradient container; vibration damping of wires going from gradient to the outside world via the gradient container; and a copper passive shield to prevent the generation of eddy currents in the metal cryostat inner bore, which in turn can vibrate and produce noise.
18. Vessel noise affects beaked whale behavior: results of a dedicated acoustic response study.
Pirotta, Enrico; Milor, Rachael; Quick, Nicola; Moretti, David; Di Marzio, Nancy; Tyack, Peter; Boyd, Ian; Hastie, Gordon
2012-01-01
Some beaked whale species are susceptible to the detrimental effects of anthropogenic noise. Most studies have concentrated on the effects of military sonar, but other forms of acoustic disturbance (e.g. shipping noise) may disrupt behavior. An experiment involving the exposure of target whale groups to intense vessel-generated noise tested how these exposures influenced the foraging behavior of Blainville's beaked whales (Mesoplodon densirostris) in the Tongue of the Ocean (Bahamas). A military array of bottom-mounted hydrophones was used to measure the response based upon changes in the spatial and temporal pattern of vocalizations. The archived acoustic data were used to compute metrics of the echolocation-based foraging behavior for 16 targeted groups, 10 groups further away on the range, and 26 non-exposed groups. The duration of foraging bouts was not significantly affected by the exposure. Changes in the hydrophone over which the group was most frequently detected occurred as the animals moved around within a foraging bout, and their number was significantly less the closer the whales were to the sound source. Non-exposed groups also had significantly more changes in the primary hydrophone than exposed groups irrespective of distance. Our results suggested that broadband ship noise caused a significant change in beaked whale behavior up to at least 5.2 kilometers away from the vessel. The observed change could potentially correspond to a restriction in the movement of groups, a period of more directional travel, a reduction in the number of individuals clicking within the group, or a response to changes in prey movement.
19. Vessel noise affects beaked whale behavior: results of a dedicated acoustic response study.
Enrico Pirotta
Full Text Available Some beaked whale species are susceptible to the detrimental effects of anthropogenic noise. Most studies have concentrated on the effects of military sonar, but other forms of acoustic disturbance (e.g. shipping noise may disrupt behavior. An experiment involving the exposure of target whale groups to intense vessel-generated noise tested how these exposures influenced the foraging behavior of Blainville's beaked whales (Mesoplodon densirostris in the Tongue of the Ocean (Bahamas. A military array of bottom-mounted hydrophones was used to measure the response based upon changes in the spatial and temporal pattern of vocalizations. The archived acoustic data were used to compute metrics of the echolocation-based foraging behavior for 16 targeted groups, 10 groups further away on the range, and 26 non-exposed groups. The duration of foraging bouts was not significantly affected by the exposure. Changes in the hydrophone over which the group was most frequently detected occurred as the animals moved around within a foraging bout, and their number was significantly less the closer the whales were to the sound source. Non-exposed groups also had significantly more changes in the primary hydrophone than exposed groups irrespective of distance. Our results suggested that broadband ship noise caused a significant change in beaked whale behavior up to at least 5.2 kilometers away from the vessel. The observed change could potentially correspond to a restriction in the movement of groups, a period of more directional travel, a reduction in the number of individuals clicking within the group, or a response to changes in prey movement.
20. Noise from high speed maglev systems: Noise sources, noise criteria, preliminary design guidelines for noise control, and recommendations for acoustical test facility for maglev research
Hanson, C. E.; Abbot, P.; Dyer, I.
1993-01-01
Noise levels from magnetically-levitated trains (maglev) at very high speed may be high enough to cause environmental noise impact in residential areas. Aeroacoustic sources dominate the sound at high speeds and guideway vibrations generate noticeable sound at low speed. In addition to high noise levels, the startle effect as a result of sudden onset of sound from a rapidly moving nearby maglev vehicle may lead to increased annoyance to neighbors of a maglev system. The report provides a base for determining the noise consequences and potential mitigation for a high speed maglev system in populated areas of the United States. Four areas are included in the study: (1) definition of noise sources; (2) development of noise criteria; (3) development of design guidelines; and (4) recommendations for a noise testing facility.
1. Prediction of the noise of flow over a cylinder by direct computation and acoustic analogy
Mani, Ali; Wang, Meng; Moin, Parviz
2007-11-01
The sound field of flow over a circular cylinder at ReD=3900 and Ma=0.4 is evaluated using Large-Eddy Simulation (LES). The acoustic results computed directly from LES are compared with those obtained using an integral solution of the Ffowcs Williams-Hawkings (FW-H) equation in conjunction with the LES source field data. The modified FW-H solution is derived using a free-space Green function which accounts for the uniform mean flow and spanwise periodicity in the flow simulation. In the implementation of the FW-H solution, the cylinder surface and three porous surfaces with different distances from the cylinder are used as integration surfaces. The effect of turbulent flow structures crossing the integration boundary on the generation of artificial noise is studied. The quadrupole terms in the FW-H equation are found to be important in canceling artificial noise regardless of their physical significance. Alternative formulations of acoustic analogy that can better handle the boundary terms will be discussed.
2. On the Application of the Raspberry Pi as an Advanced Acoustic Sensor Network for Noise Monitoring
Juan Emilio Noriega-Linares
2016-10-01
Full Text Available The concept of Smart Cities and the monitoring of environmental parameters is an area of research that has attracted scientific attention during the last decade. These environmental parameters are well-known as important factors in their affection towards people. Massive monitoring of this kind of parameters in cities is an expensive and complex task. Recent technologies of low-cost computing and low-power devices have opened researchers to a wide and more accessible research field, developing monitoring devices for deploying Wireless Sensor Networks. Gathering information from them, improved urban plans could be carried out and the information could help citizens. In this work, the prototyping of a low-cost acoustic sensor based on the Raspberry Pi platform for its use in the analysis of the sound field is described. The device is also connected to the cloud to share results in real time. The computation resources of the Raspberry Pi allow treating high quality audio for calculating acoustic parameters. A pilot test was carried out with the installation of two acoustic devices in the refurbishment works of a neighbourhood. In this deployment, the evaluation of these devices through long-term measurements was carried out, obtaining several acoustic parameters in real time for its broadcasting and study. This test has shown the Raspberry Pi as a powerful and affordable computing core of a low-cost device, but also the pilot test has served as a query tool for the inhabitants of the neighbourhood to be more aware about the noise in their own place of residence.
3. Observation of the Fundamental Nyquist Noise Limit in an Ultra-High $Q$-Factor Cryogenic Bulk Acoustic Wave Cavity
Goryachev, Maxim; van Kann, Frank; Galliou, Serge; Tobar, Michael E
2014-01-01
Thermal Nyquist noise fluctuations of high-$Q$ Bulk Acoustic Wave (BAW) cavities have been observed at cryogenic temperatures with a DC Superconducting Quantum Interference Device (SQUID) amplifier. High $Q$ modes with bandwidths of few tens of milliHz produce thermal fluctuations with a Signal-To-Noise ratio of up to 23dB. The estimated effective temperature from the Nyquist noise is in good agreement with the physical temperature of the device, confirming the validity of the equivalent circuit model and the non-existence of any excess resonator self-noise. The measurements also confirm that the quality factor remains extremely high ($Q>10^8$ at low order overtones) for very weak (thermal) system motion at low temperatures, when compared to values measured with relatively strong external excitation. This result represents an enabling step towards operating such a high-Q acoustic device at the standard quantum limit.
4. Acoustic noise reduction for vehicle engines. (Latest citations from the US Patent Bibliographic file with exemplary claims). Published Search
1994-06-01
The bibliography contains citations of selected patents concerning methods, devices, and materials to reduce acoustic noise in vehicle engines. Vehicles covered include automobiles, railway locomotives, agricultural tractors, and aircraft. Internal combustion, diesel, and gas turbine engines are covered. (Contains a minimum of 188 citations and includes a subject term index and title list.)
5. Emergence of the Green’s Functions from Noise and Passive Acoustic Remote Sensing of Ocean Dynamics
2010-09-30
environments, Acta Acustica united with Acustica , 95, no. 6, p. 963–974 (2009b) [published, refereed] O. A. Godin, Emergence of deterministic Green’s...Godin, Emergence of acoustic Green’s functions from time averages of ambient noise, Acta Acustica united with Acustica (2010) [in press, refereed
6. What's All the Noise? Differentiating Dimensions of Acoustic Stress and the Limits to Meta-Analysis: Reply to Smith (2012)
Szalma, J. L.; Hancock, P. A.
2012-01-01
Smith (2012) has provided pertinent observations on our recently published meta-analytic review (Szalma & Hancock, 2011) of the effects of acoustic noise on performance. His main points are as follows: (a) our review excluded some areas of research; (b) there were conceptual problems with our moderator analyses; and (c) limitations to…
7. Development of a model to assess acoustic treatments to reduce railway noise
Jeong, H.; Squicciarini, G.; Thompson, D. J.; Ryue, J.
2016-09-01
Porous materials have recently been used in absorptive treatments around railway tracks to reduce noise emissions. To investigate the effect of porous materials, a finite element model has been developed. 2D models for porous materials have been considered either as an equivalent fluid or as a poroelastic material based on the Biot theory. The two models have been validated and compared with each other to check the effect of the skeleton vibration. The poroelastic FE model has been coupled with a 2D acoustic boundary element model for use in railway applications. The results show that it may be necessary to include the frame vibration, especially at low frequencies where a frame resonance occurs. A method for the characterization of porous materials is also discussed. From this it is shown that the elastic properties of the material determine the resonance frequency and the magnitude.
8. Characterization of acoustic noise in a neonatal intensive care unit MRI system
Tkach, Jean A.; Li, Yu; Pratt, Ronald G.; Loew, Wolfgang; Daniels, Barret R.; Giaquinto, Randy O.; Dumoulin, Charles L. [Cincinnati Children' s Hospital Medical Center, Imaging Research Center, Department of Radiology, Cincinnati, OH (United States); Baroch, Kelly A. [Cincinnati Children' s Hospital Medical Center, Division of Audiology, Cincinnati, OH (United States); Merhar, Stephanie L. [Cincinnati Children' s Hospital Medical Center, Division of Neonatology and Pulmonary Biology, Perinatal Institute, Cincinnati, OH (United States); Kline-Fath, Beth M. [Cincinnati Children' s Hospital Medical Center, Department of Radiology, Cincinnati, OH (United States)
2014-08-15
To eliminate the medical risks and logistical challenges of transporting infants from the neonatal intensive care unit (NICU) to the radiology department for magnetic resonance imaging, a small-footprint 1.5-T MRI scanner has been developed for neonatal imaging within the NICU. MRI is known to be noisy, and exposure to excessive acoustic noise has the potential to elicit physiological distress and impact development in the term and preterm infant. To measure and compare the acoustic noise properties of the NICU MRI system against those of a conventional 1.5-T MRI system. We performed sound pressure level measurements in the NICU MRI scanner and in a conventional adult-size whole-body 1.5-T MRI system. Sound pressure level measurements were made for six standard clinical MR imaging protocols. The average sound pressure level value, reported in unweighted (dB) and A-weighted (dBA) decibels for all six imaging pulse sequences, was 73.8 dB and 88 dBA for the NICU scanner, and 87 dB and 98.4 dBA for the conventional MRI scanner. The sound pressure level values measured on the NICU scanner for each of the six MR imaging pulse sequences were consistently and significantly (P = 0.03) lower, with an average difference of 14.2 dB (range 10-21 dB) and 11 dBA (range 5-18 dBA). The sound pressure level frequency response of the two MR systems showed a similar harmonic structure above 200 Hz for all imaging sequences. The amplitude, however, was appreciably lower for the NICU scanner, by as much as 30 dB, for frequencies below 200 Hz. The NICU MRI system is quieter than conventional MRI scanners, improving safety for the neonate and facilitating siting of the unit within the NICU. (orig.)
9. Optimal virtual sensing for active noise control in a rigid-walled acoustic duct
Petersen, Dick; Zander, Anthony C.; Cazzolato, Ben S.; Hansen, Colin H.
2005-11-01
The performance of local active noise control systems is generally limited by the small sizes of the zones of quiet created at the error sensors. This is often exacerbated by the fact that the error sensors cannot always be located close to an observer's ears. Virtual sensing is a method that can move the zone of quiet away from the physical location of the transducers to a desired location, such as an observer's ear. In this article, analytical expressions are derived for optimal virtual sensing in a rigid-walled acoustic duct with arbitrary termination conditions. The expressions are derived for tonal excitations, and are obtained by employing a traveling wave model of a rigid-walled acoustic duct. It is shown that the optimal solution for the virtual sensing microphone weights is independent of the source location and microphone locations. It is also shown that, theoretically, it is possible to obtain infinite reductions at the virtual location. The analytical expressions are compared with forward difference prediction techniques. The results demonstrate that the maximum attenuation, that theoretically can be obtained at the virtual location using forward difference prediction techniques, is expected to decrease for higher excitation frequencies and larger virtual distances.
10. Testing Time and Frequency Fiber-Optic Link Transfer by Hardware Emulation of Acoustic-Band Optical Noise
Lipiński Marcin
2016-06-01
Full Text Available The low-frequency optical-signal phase noise induced by mechanical vibration of the base occurs in field-deployed fibers. Typical telecommunication data transfer is insensitive to this type of noise but the phenomenon may influence links dedicated to precise Time and Frequency (T&F fiber-optic transfer that exploit the idea of stabilization of phase or propagation delay of the link. To measure effectiveness of suppression of acoustic noise in such a link, a dedicated measurement setup is necessary. The setup should enable to introduce a low-frequency phase corruption to the optical signal in a controllable way. In the paper, a concept of a setup in which the mechanically induced acoustic-band optical signal phase corruption is described and its own features and measured parameters are presented. Next, the experimental measurement results of the T&F transfer TFTS-2 system’s immunity as a function of the fibre-optic length vs. the acoustic-band noise are presented. Then, the dependency of the system immunity on the location of a noise source along the link is also pointed out.
11. High-speed imaging, acoustic features, and aeroacoustic computations of jet noise from Strombolian (and Vulcanian) explosions
Taddeucci, J.; Sesterhenn, J.; Scarlato, P.; Stampka, K.; Del Bello, E.; Pena Fernandez, J. J.; Gaudin, D.
2014-05-01
High-speed imaging of explosive eruptions at Stromboli (Italy), Fuego (Guatemala), and Yasur (Vanuatu) volcanoes allowed visualization of pressure waves from seconds-long explosions. From the explosion jets, waves radiate with variable geometry, timing, and apparent direction and velocity. Both the explosion jets and their wave fields are replicated well by numerical simulations of supersonic jets impulsively released from a pressurized vessel. The scaled acoustic signal from one explosion at Stromboli displays a frequency pattern with an excellent match to those from the simulated jets. We conclude that both the observed waves and the audible sound from the explosions are jet noise, i.e., the typical acoustic field radiating from high-velocity jets. Volcanic jet noise was previously quantified only in the infrasonic emissions from large, sub-Plinian to Plinian eruptions. Our combined approach allows us to define the spatial and temporal evolution of audible jet noise from supersonic jets in small-scale volcanic eruptions.
12. Study of performance of acoustic fixture for using in noise reduction rate tests of hearing protection devices
zam Biabani
2016-06-01
Full Text Available Introduction:One of the recommended methods for evaluation effectiveness of hearing protection is use the acoustic fixture accordance with standard ISO 4869-3. The aim of this study was evaluate the acoustic performance of fixture for using in noise reduction rate tests of hearing protection devices in the laboratory. Methods: In this cross-sectional study , noise reduction rates of five common ear muffs used in the Iran industries were investigated based on the ISO 11904 standard, microphone in real ear method, using noise dosimeter (SVANTEK , Model SV102 equipped with microphone SV25 model which can install inside the ear on 30 subjects under laboratory conditions. Also, noise reduction rate of earmuffs was determined using the fixture model AVASINA9402 accordance with standard procedures. Data were analyzed using the software SPSS21. Results: The results showed the real noise reduction rates of the earmuffs on the studied subjects are from 59% to 94% nominal reduction rates. That rates for the ear muffs on the studied fixture are from 64% to 92.The results showed that the noise reduction rates of the ear muffs on subjects compared with and noise reduction rates of the ear muffs on fixture were not statistically significant (p> 0.05. Conclusion: The results showed the accuracy of noise reduction rate of earmuffs using the fixture compared with real subjects is acceptable. Hence, the fixture is good choice for environments where there’s no possibility of acoustic evaluation on real subjects, also for quality control of productions in the earmuff manufacturers.
13. Acoustic plane waves normally incident on a clamped panel in a rectangular duct. [to explain noise reduction curves for reducing interior noise in aircraft
Unz, H.; Roskam, J.
1979-01-01
The theory of acoustic plane wave normally incident on a clamped panel in a rectangular duct is developed. The coupling theory between the elastic vibrations of the panel (plate) and the acoustic wave propagation in infinite space and in the rectangular duct is considered. The partial differential equation which governs the vibration of the panel (plate) is modified by adding to its stiffness (spring) forces and damping forces, and the fundamental resonance frequency and the attenuation factor are discussed. The noise reduction expression based on the theory is found to agree well with the corresponding experimental data of a sample aluminum panel in the mass controlled region, the damping controlled region, and the stiffness controlled region. All the frequency positions of the upward and downward resonance spikes in the sample experimental data are identified theoretically as resulting from four cross interacting major resonance phenomena: the cavity resonance, the acoustic resonance, the plate resonance, and the wooden back panel resonance.
14. Concurrent identification of aero-acoustic scattering and noise sources at a flow duct singularity in low Mach number flow
Sovardi, Carlo; Jaensch, Stefan; Polifke, Wolfgang
2016-09-01
A numerical method to concurrently characterize both aeroacoustic scattering and noise sources at a duct singularity is presented. This approach combines Large Eddy Simulation (LES) with techniques of System Identification (SI): In a first step, a highly resolved LES with external broadband acoustic excitation is carried out. Subsequently, time series data extracted from the LES are post-processed by means of SI to model both acoustic propagation and noise generation. The present work studies the aero-acoustic characteristics of an orifice placed in a duct at low flow Mach numbers with the "LES-SI" method. Parametric SI based on the Box-Jenkins mathematical structure is employed, with a prediction error approach that utilizes correlation analysis of the output residuals to avoid overfitting. Uncertainties of model parameters due to the finite length of times series are quantified in terms of confidence intervals. Numerical results for acoustic scattering matrices and power spectral densities of broad-band noise are validated against experimental measurements over a wide range of frequencies below the cut-off frequency of the duct.
15. A geometric Model for the Spatial Correlation of an Acoustic Vector Field in Surface-generated Noise
Yiwang Huang; Qunyan Ren; Ting Li
2012-01-01
Spatial correlation of sound pressure and particle velocity of the surface noise in horizontally stratified media was demonstrated,with directional noise sources uniformly distributed on the ocean surface.In the evaluation of particle velocity,plane wave approximation was applied to each incident ray.Due to the equivalence of the sound source correlation property and its directivity,solutions for the spatial correlation of the field were transformed into the integration of the coherent function generated by a single directional source.As a typical horizontally stratified media,surface noise in a perfect waveguide was investigated.Correlation coefficients given by normal mode and geometric models show satisfactory agreement.Also,the normalized covariance between sound pressure and the vertical component of particle velocity is proportional to acoustic absorption coefficient,while that of the surface noise in semi-infinitely homogeneous space is zero.
16. TU-F-CAMPUS-I-04: Head-Only Asymmetric Gradient System Evaluation: ACR Image Quality and Acoustic Noise
Weavers, P; Shu, Y; Tao, S; Bernstein, M [Mayo Clinic, Rochester, Minnesota (United States); Lee, S; Piel, J; Foo, T [GE Global Research, Niskayuna, NY (United States); Mathieu, J-B [GE Healthcare, Florence, SC (Italy)
2015-06-15
17. Acoustic signal detection through the cross-correlation method in experiments with different signal to noise ratio and reverberation conditions
Adrián-Martínez, S; Bou-Cabo, M; Felis, I; Llorens, C; Martínez-Mora, J A; Saldaña, M
2015-01-01
The study and application of signal detection techniques based on cross-correlation method for acoustic transient signals in noisy and reverberant environments are presented. These techniques are shown to provide high signal to noise ratio, good signal discernment from very close echoes and accurate detection of signal arrival time. The proposed methodology has been tested on real data collected in environments and conditions where its benefits can be shown. This work focuses on the acoustic detection applied to tasks of positioning in underwater structures and calibration such those as ANTARES and KM3NeT deep-sea neutrino telescopes, as well as, in particle detection through acoustic events for the COUPP/PICO detectors. Moreover, a method for obtaining the real amplitude of the signal in time (voltage) by using cross correlation has been developed and tested and is described in this work.
18. Observation of the Kibble-Zurek Mechanism in Microscopic Acoustic Crackling Noises
Ghaffari, H. O.; Griffth, W. A.; Benson, P. M.; Xia, K.; Young, R. P.
2016-02-01
Characterizing the fast evolution of microstructural defects is key to understanding “crackling” phenomena during the deformation of solid materials. For example, it has been proposed using atomistic simulations of crack propagation in elastic materials that the formation of a nonlinear hyperelastic or plastic zone around moving crack tips controls crack velocity. To date, progress in understanding the physics of this critical zone has been limited due to the lack of data describing the complex physical processes that operate near microscopic crack tips. We show, by analyzing many acoustic emission events during rock deformation experiments, that the signature of this nonlinear zone maps directly to crackling noises. In particular, we characterize a weakening zone that forms near the moving crack tips using functional networks, and we determine the scaling law between the formation of damages (defects) and the traversal rate across the critical point of transition. Moreover, we show that the correlation length near the transition remains effectively frozen. This is the main underlying hypothesis behind the Kibble-Zurek mechanism (KZM) and the obtained power-law scaling verifies the main prediction of KZM.
19. Characterization of electro-acoustics impedance and its application to active noise control
HOU Hong; YANG Jianhua
2004-01-01
Characteristics of radiation impedance and its inducing variation of electrical impedance for a controllable source have been investigated. An impedance-based error criterion has been proposed and its application to Active Noise Control is demonstrated through a coil driven loudspeaker. A general formula of radiation impedance is derived for two control strategies, according to the criterion of total acoustic power output. The radiation impedances of some commonly used sound sources are calculated. We discuss in detail the relation between variation of the input electrical impedance and radiation impedance for the two control strategies. The measured data of the input electrical impedance from a loudspeaker agree fairly well with theoretical analysis. An AC- bridge circuit is designed in order to measure the weak variation of electrical impedance resulted from radiation impedance. The bridge relative output is unique for a certain control strategy, from which an impedance-based error criterion is then proposed and the implementation of its application to an active control system is analyzed.Numerical results of such criterion are presented. An analogue control system is set up and experiments are carried out in a semi-anechoic chamber to verify the new control approach.
20. Tone and Broadband Noise Separation from Acoustic Data of a Scale-Model Counter-Rotating Open Rotor
Sree, David; Stephens, David B.
2014-01-01
Renewed interest in contra-rotating open rotor technology for aircraft propulsion application has prompted the development of advanced diagnostic tools for better design and improved acoustical performance. In particular, the determination of tonal and broadband components of open rotor acoustic spectra is essential for properly assessing the noise control parameters and also for validating the open rotor noise simulation codes. The technique of phase averaging has been employed to separate the tone and broadband components from a single rotor, but this method does not work for the two-shaft contra-rotating open rotor. A new signal processing technique was recently developed to process the contra-rotating open rotor acoustic data. The technique was first tested using acoustic data taken of a hobby aircraft open rotor propeller, and reported previously. The intent of the present work is to verify and validate the applicability of the new technique to a realistic one-fifth scale open rotor model which has 12 forward and 10 aft contra-rotating blades operating at realistic forward flight Mach numbers and tip speeds. The results and discussions of that study are presented in this paper.
1. Tone and Broadband Noise Separation from Acoustic Data of a Scale-Model Contra-Rotating Open Rotor
Sree, Dave; Stephens, David B.
2014-01-01
Renewed interest in contra-rotating open rotor technology for aircraft propulsion application has prompted the development of advanced diagnostic tools for better design and improved acoustical performance. In particular, the determination of tonal and broadband components of open rotor acoustic spectra is essential for properly assessing the noise control parameters and also for validating the open rotor noise simulation codes. The technique of phase averaging has been employed to separate the tone and broadband components from a single rotor, but this method does not work for the two-shaft contra-rotating open rotor. A new signal processing technique was recently developed to process the contra-rotating open rotor acoustic data. The technique was first tested using acoustic data taken of a hobby aircraft open rotor propeller, and reported previously. The intent of the present work is to verify and validate the applicability of the new technique to a realistic one-fifth scale open rotor model which has 12 forward and 10 aft contra-rotating blades operating at realistic forward flight Mach numbers and tip speeds. The results and discussions of that study are presented in this paper.
2. NASA/AHS rotorcraft noise reduction program - NASA Langley Acoustics Division contributions
Martin, Ruth M.
1989-01-01
An account is given of the contributions made by NASA-Langley's rotorcraft noise research programs over the last five years. Attention has been given to the broadband and blade-vortex interaction noise sources; both analytical and empirical noise-prediction codes have been developed and validated for several rotor noise sources, and the 'Rotonet' comprehensive system-noise prediction capability has been instituted. Among the technologies explored for helicopter noise reduction have been higher harmonic control and active vibration-suppression.
3. 智能软降噪算法研究%AN INTELLIGENT SOFT ACOUSTIC NOISE REDUCTION ALGORITHM
叶尔江·哈力木; 曼苏乐; 古丽米拉·克孜尔别克; 张秀彬
2013-01-01
In this paper, an intelligent soft acoustic noise reduction algorithm is proposed in light of the properties of complex, chaotic and unknown the noise spatial distribution has. Based on defining the description of typical "unknown noise signal groups" in the definition of " generalised noise" , the algorithm employs decomposition operation of transformation matrix to make the noise sources express their spatial location in polar coordinate, therefore it is able to decompose and locate the noise sources emerged from different positions of spatial regions with various emission direction angles. At the same time, this algorithm makes use of the " unknown noise signal groups containing foreseen specific frequency signals" , and extracts the useful "foreseen singles" in condition of removing all the noise interference to achieve the effect of effective cancelling out the noise signals.%针对噪声空间分布的复杂性、混沌性和未知性提出一种智能软降噪算法.该算法在建立“广义噪声”定义下典型“未知噪声信号群”描述的基础上,通过转换矩阵的分解运算,使得噪声源以极坐标来表达其空间位置,因此能够将来自空域不同位置及其发射方向角的噪声源进行分解与定位.同时利用“包含预知特定频率信号的未知噪声信号群”,将其中有用“预知信号”在去除所有噪声干扰的情况下提取出来,达到高效镇噪效果.
4. Design and optimization of a noise reduction system for infrasonic measurements using elements with low acoustic impedance.
Alcoverro, Benoit; Le Pichon, Alexis
2005-04-01
The implementation of the infrasound network of the International Monitoring System (IMS) for the enforcement of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) increases the effort in the design of suitable noise reducer systems. In this paper we present a new design consisting of low impedance elements. The dimensioning and the optimization of this discrete mechanical system are based on numerical simulations, including a complete electroacoustical modeling and a realistic wind-noise model. The frequency response and the noise reduction obtained for a given wind speed are compared to statistical noise measurements in the [0.02-4] Hz frequency band. The effects of the constructive parameters-the length of the pipes, inner diameters, summing volume, and number of air inlets-are investigated through a parametric study. The studied system consists of 32 air inlets distributed along an overall diameter of 16 m. Its frequency response is flat up to 4 Hz. For a 2 m/s wind speed, the maximal noise reduction obtained is 15 dB between 0.5 and 4 Hz. At lower frequencies, the noise reduction is improved by the use of a system of larger diameter. The main drawback is the high-frequency limitation introduced by acoustical resonances inside the pipes.
5. Acoustic textiles
Nayak, Rajkishore
2016-01-01
This book highlights the manufacturing and applications of acoustic textiles in various industries. It also includes examples from different industries in which acoustic textiles can be used to absorb noise and help reduce the impact of noise at the workplace. Given the importance of noise reduction in the working environment in several industries, the book offers a valuable guide for companies, educators and researchers involved with acoustic materials.
6. Acoustic Database for Turbofan Engine Core-Noise Sources. I; Volume
Gordon, Grant
2015-01-01
were processed using software that accounts for the effects of convective and conductive heat transfer. The software was developed under previous NASA sponsored programs. Compensated temperature spectra and compensated time histories corresponding to the dynamic temperature of the gas stream were generated. Auto-spectral and cross-spectral analyses of the data were performed to investigate spectral features, acoustic circumferential mode content, signal coherence, and time delays. The dynamic temperature data exhibit a wideband and fairly flat spectral content. The temperature spectra do not change substantially with operating speed. The pressure spectra in the combustor and ITD exhibit generally similar shapes and amplitudes, making it difficult to identify any features that suggest the presence of indirect combustion noise. Cross-spectral analysis reveal a strong correlation between pressure and temperature fluctuations in the ITD, but little correlation between temperature fluctuations at the entrance of the HPT and pressure fluctuations downstream of it. Temperature fluctuations at the entrance of the low pressure turbine were an order of magnitude smaller than those at the entrance to the high pressure turbine. Time delay analysis of the temperature fluctuations in the combustor was inconclusive, perhaps due to the substantial mixing that occurs between the upstream and downstream locations. Time delay analysis of the temperature fluctuations in the ITD indicate that they convect at the mean flow speed. Analysis of the data did not reveal any convincing indications of the presence of indirect combustion noise. However, this analysis has been preliminary and additional exploration of the data is recommended including the use of more sophisticated signal processing to explore subtle issues that have been revealed but which are not yet fully understood or explained.
7. Acoustic Performance of Novel Fan Noise Reduction Technologies for a High Bypass Model Turbofan at Simulated Flights Conditions
Elliott, David M.; Woodward, Richard P.; Podboy, Gary G.
2010-01-01
Two novel fan noise reduction technologies, over the rotor acoustic treatment and soft stator vane technologies, were tested in an ultra-high bypass ratio turbofan model in the NASA Glenn Research Center s 9- by 15-Foot Low-Speed Wind Tunnel. The performance of these technologies was compared to that of the baseline fan configuration, which did not have these technologies. Sideline acoustic data and hot film flow data were acquired and are used to determine the effectiveness of the various treatments. The material used for the over the rotor treatment was foam metal and two different types were used. The soft stator vanes had several internal cavities tuned to target certain frequencies. In order to accommodate the cavities it was necessary to use a cut-on stator to demonstrate the soft vane concept.
8. Noise reduction as affected by the extent and distribution of acoustic treatment in a turbofan engine inlet
Minner, G. L.; Homyak, L.
1976-01-01
An inlet noise suppressor for a TF-34 engine designed to have three acoustically treated rings was tested with several different ring arrangements. The configurations included: all three rings; two outer rings; single outer ring; single intermediate ring, and finally no rings. It was expected that as rings were removed, the acoustic performance would be degraded considerably. While a degradation occurred, it was not as large as predictions indicated. In fact, the prediction showed good agreement with the data only for the full-ring inlet configuration. The under-predictions which occurred with ring removal were believed a result of ignoring the presence of spinning modes which are known to damp more rapidly in cylindrical ducts than would be predicted by least attenuated mode or plane wave analysis.
9. Dual-tree complex wavelet transform and SVD based acoustic noise reduction and its application in leak detection for natural gas pipeline
Yu, Xuchao; Liang, Wei; Zhang, Laibin; Jin, Hao; Qiu, Jingwei
2016-05-01
During the last decades, leak detection for natural gas pipeline has become one of the paramount concerns of pipeline operators and researchers across the globe. However, acoustic wave method has been proved to be an effective way to identify and localize leakage for gas pipeline. Considering the fact that noises inevitably exist in the acoustic signals collected, noise reduction should be enforced on the signals for subsequent data mining and analysis. Thus, an integrated acoustic noise reduction method based on DTCWT and SVD is proposed in this study. The method is put forward based on the idea that noise reduction strategy should match the characteristics of the noisy signal. According to previous studies, it is known that the energy of acoustic signals collected under leaking condition is mainly concentrated in low-frequency portion (0-100 Hz). And ultralow-frequency component (0-5 Hz), which is taken as the characteristic frequency band in this study, can propagate a relatively longer distance and be captured by sensors. Therefore, in order to filter the noises and to reserve the characteristic frequency band, DTCWT is taken as the core to conduct multilevel decomposition and refining for acoustic signals and SVD is employed to eliminate noises in non-characteristic bands. Both simulation and field experiments show that DTCWT-SVD is an excellent method for acoustic noise reduction. At the end of this study, application in leakage localization shows that it becomes much easier and a little more accurate to estimate the location of leak hole after noise reduction by DTCWT-SVD.
10. Acoustic and Laser Doppler Anemometer Results for Confluent, 22-Lobed, and Unique-Lobed Mixer Exhaust Systems for Subsonic Jet Noise Reduction
Salikuddin, M.; Martens, S.; Shin, H.; Majjigi, R. K.; Krejsa, Gene (Technical Monitor)
2002-01-01
The objective of this task was to develop a design methodology and noise reduction concepts for high bypass exhaust systems which could be applied to both existing production and new advanced engine designs. Special emphasis was given to engine cycles with bypass ratios in the range of 4:1 to 7:1, where jet mixing noise was a primary noise source at full power takeoff conditions. The goal of this effort was to develop the design methodology for mixed-flow exhaust systems and other novel noise reduction concepts that would yield 3 EPNdB noise reduction relative to 1992 baseline technology. Two multi-lobed mixers, a 22-lobed axisymmetric and a 21-lobed with a unique lobe, were designed. These mixers along with a confluent mixer were tested with several fan nozzles of different lengths with and without acoustic treatment in GEAE's Cell 41 under the current subtask (Subtask C). In addition to the acoustic and LDA tests for the model mixer exhaust systems, a semi-empirical noise prediction method for mixer exhaust system is developed. Effort was also made to implement flowfield data for noise prediction by utilizing MGB code. In general, this study established an aero and acoustic diagnostic database to calibrate and refine current aero and acoustic prediction tools.
11. Application of acoustic noise and self-potential localization techniques to a buried hydrothermal vent (Waimangu Old Geyser site, New Zealand)
Vandemeulebrouck, J.; Roux, P.; Gouédard, P.; Legaz, A.; Revil, A.; Hurst, A. W.; Bolève, A.; Jardani, A.
2010-02-01
A seismo-acoustic and self-potential survey has been performed in the hydrothermal area of the old Waimangu Geyser (New Zealand), which was violently erupting a century ago. Nowadays, no surface activity is visible there. We set-up an array of 16 geophones and recorded a high and steady acoustic ambient noise. We applied the matched field processing (MFP) approach to the acoustic data to locate the sources responsible for the ambient noise. The white noise constraint processor reveals the presence of a unique and well-focused acoustic source at a depth of 1.5 m below the seismic array. For this very shallow source, the application of MFP enabled the determination of both the source location and the dispersion curve of seismic velocity. The study was completed by self-potential (SP) measurements on several profiles around the acoustic noise source, which displayed a large positive anomaly above it. The results of the SP inversion gave an electric streaming current density source very close to the acoustic one. Both sources likely belong to a shallow hydrothermal structure interpreted as a small convective cell of boiling water beneath an impermeable layer. The joint application of these methods is a promising technique to recognize hydrothermal structures and to study their dynamics.
12. A seismic field test with a Low-level Acoustic Combustion Source and Pseudo-Noise codes
Askeland, Bjørn; Ruud, Bent Ole; Hobæk, Halvor; Mjelde, Rolf
2009-01-01
The Low-level Acoustic Combustion Source (LACS) which can fire its pulses at a high rate, has been tested successfully as a seismic marine source on shallow ice-age sediments in Byfjorden at Bergen, Norway. Pseudo-Noise pulsed signals with spiky autocorrelation functions were used to detect the sediments. Each transmitted sequence lasted 10 s and contained 43 pulses. While correlation gave a blurry result, deconvolution between the near-field recordings and the streamer recordings gave a clear seismic section. Compared to the section acquired with single air-gun shots along the same profile, the LACS gave a more clear presentation of the sediments and basement.
13. The noise environment of a school classroom due to the operation of utility helicopters. [acoustic measurements of helicopter noise during flight over building
Hilton, D. A.; Pegg, R. J.
1974-01-01
Noise measurements under controlled conditions have been made inside and outside of a school building during flyover operations of four different helicopters. The helicopters were operated at a condition considered typical for a police patrol mission. Flyovers were made at an altitude of 500 ft and an airspeed of 45 miles per hour. During these operations acoustic measurements were made inside and outside of the school building with the windows closed and then open. The outside noise measurements during helicopter flyovers indicate that the outside db(A) levels were approximately the same for all test helicopters. For the windows closed case, significant reductions for the inside measured db(A) values were noted for all overflights. These reductions were approximately 20 db(A); similar reductions were noted in other subjective measuring units. The measured internal db(A) levels with the windows open exceeded published classroom noise criteria values; however, for the windows-closed case they are in general agreement with the criteria values.
14. Near noise field characteristics of Nike rocket motors for application to space vehicle payload acoustic qualification
Hilton, D. A.; Bruton, D.
1977-01-01
Results of a series of noise measurements that were made under controlled conditions during the static firing of two Nike solid propellant rocket motors are presented. The usefulness of these motors as sources for general spacecraft noise testing was assessed, and the noise expected in the cargo bay of the orbiter was reproduced. Brief descriptions of the Nike motor, the general procedures utilized for the noise tests, and representative noise data including overall sound pressure levels, one third octave band spectra, and octave band spectra were reviewed. Data are presented on two motors of different ages in order to show the similarity between noise measurements made on motors having different loading dates. The measured noise from these tests is then compared to that estimated for the space shuttle orbiter cargo bay.
15. Acoustic evaluation and adjustment of an open-plan office through architectural design and noise control.
Passero, Carolina Reich Marcon; Zannin, Paulo Henrique Trombetta
2012-11-01
Arranging office space into a single open room offers advantages in terms of easy exchange of information and interaction among coworkers, but reduces privacy and acoustic comfort. Thus, the purpose of this work was to evaluate the acoustic quality of a real open-plan office and to propose changes in the room to improve the acoustic conditioning of this office. The computational model of the office under study was calibrated based on RT and STI measurements. Predictions were made of the RT and STI, which generated the radius of distraction r(D), and the rate of spatial decay of sound pressure levels per distance doubling DL(2) in the real conditions of the office and after modifications of the room. The insertion of dividers between work stations and an increase in the ceiling's sound absorption improved the acoustic conditions in the office under study.
16. Noise
Noise is all around you, from televisions and radios to lawn mowers and washing machines. Normally, you ... sensitive structures of the inner ear and cause noise-induced hearing loss. More than 30 million Americans ...
17. Recommendations for improved acceptance of wind farm projects in France with regard to acoustic noise
Dutilleux, P.; Gabriel, J. [Deutsches Windenergie-Institut GmbH (DEWI), Wilhelmshaven (Germany)
2008-03-15
From the consideration of the various acoustic issues that are raised by wind farm projects, the similarities and differences of approaches and methods used in France and in Germany are reviewed. Recommendations to the acousticians, to the wind turbine manufacturers, to the developers and to the operators are derived with the objective of improving the acoustic quality of wind farm projects and their acceptance by the population. (orig.)
18. Experimental and theoretical characterization of acoustic noise from a 7.6 m diameter yaw controlled teetered rotor wind turbine
Moroz, E. [Univ. of Texas at El Paso, Dept. of Mechanical and Industrial Engineering, El Paso, TX (United States)
1997-12-31
An experimental investigation into the acoustic noise from a small (7.6 m diameter) teetered rotor wind turbine, set at various yaw angles up to 90 degrees of yaw, was conducted. The results revealed a 1/3 octave spectra which was dominated by a broad peak in the higher frequency range, at all yaw angles investigated. This prompted a theoretical investigation to reveal the mechanisms producing the dominant feature in the experimentally obtained noise spectra and resulted in the development of a wind turbine aerodynamic noise prediction coce, WTNOISE. The location near busy roads and the relatively rough terrain of the wind test site caused difficulties in obtaining useful noise spectral information below 500Hz. However, sufficiently good data was obtained above 500Hz to clearly show a dominant hump in the spectrum, centered between 3000 and 4000Hz. Although the local Reynolds number for the blade elements was around 500,000 and one might expect Laminar flow over a significant portion of the blade, the data did not match the noise spectra predicted when Laminar flow was assumed. Given the relatively poor surface quality of the rotor blades and the high turbulence of the test site it was therefore assumed that the boundary layer on the blade may have tripped relatively early and that the turbulent flow setting should be used. This assumption led to a much better correlation between experiment and predictions. The WTNOISE code indicated that the broad peak in the spectrum was most likely caused by trailing edge bluntness noise. Unfortunately time did not allow for modifications to the trailing edge to be investigated. (au)
19. Experimental investigation of shock-cell noise reduction for dual-stream nozzles in simulated flight comprehensive data report. Volume 1: Test nozzles and acoustic data
Yamamoto, K.; Janardan, B. A.; Brausch, J. F.; Hoerst, D. J.; Price, A. O.
1984-01-01
Parameters which contribute to supersonic jet shock noise were investigated for the purpose of determining means to reduce such noise generation to acceptable levels. Six dual-stream test nozzles with varying flow passage and plug closure designs were evaluated under simulated flight conditions in an anechoic chamber. All nozzles had combined convergent-divergent or convergent flow passages. Acoustic behavior as a function of nozzle flow passage geometry was measured. The acoustic data consist primarily of 1/3 octave band sound pressure levels and overall sound pressure levels. Detailed schematics and geometric characteristics of the six scale model nozzle configurations and acoustic test point definitions are presented. Tabulation of aerodynamic test conditions and a computer listing of the measured acoustic data are displayed.
20. Still in Womb: Intrauterine Acoustic Embedded Active Noise Control for Infant Incubators
Lichuan Liu
2008-01-01
effect”, that is, by using intrauterine and maternal heart sounds, proven to be beneficial to infant health, for soothing the infant and masking the residual noise. A computer model for audio-integrated noise cancellation utilizing experimentally measured transfer functions is developed for simulations using real medical equipment noise. The simulation of the audio integrated ANC system produced optimal results and the system was further validated by real-time experiments to be robust and efficient.
1. An Intelligent Sensor Array Distributed System for Vibration Analysis and Acoustic Noise Characterization of a Linear Switched Reluctance Actuator
2012-01-01
This paper proposes a distributed system for analysis and monitoring (DSAM) of vibrations and acoustic noise, which consists of an array of intelligent modules, sensor modules, communication bus and a host PC acting as data center. The main advantages of the DSAM are its modularity, scalability, and flexibility for use of different type of sensors/transducers, with analog or digital outputs, and for signals of different nature. Its final cost is also significantly lower than other available commercial solutions. The system is reconfigurable, can operate either with synchronous or asynchronous modes, with programmable sampling frequencies, 8-bit or 12-bit resolution and a memory buffer of 15 kbyte. It allows real-time data-acquisition for signals of different nature, in applications that require a large number of sensors, thus it is suited for monitoring of vibrations in Linear Switched Reluctance Actuators (LSRAs). The acquired data allows the full characterization of the LSRA in terms of its response to vibrations of structural origins, and the vibrations and acoustic noise emitted under normal operation. The DSAM can also be used for electrical machine condition monitoring, machine fault diagnosis, structural characterization and monitoring, among other applications. PMID:22969364
2. An Intelligent Sensor Array Distributed System for Vibration Analysis and Acoustic Noise Characterization of a Linear Switched Reluctance Actuator
2012-06-01
Full Text Available This paper proposes a distributed system for analysis and monitoring (DSAM of vibrations and acoustic noise, which consists of an array of intelligent modules, sensor modules, communication bus and a host PC acting as data center. The main advantages of the DSAM are its modularity, scalability, and flexibility for use of different type of sensors/transducers, with analog or digital outputs, and for signals of different nature. Its final cost is also significantly lower than other available commercial solutions. The system is reconfigurable, can operate either with synchronous or asynchronous modes, with programmable sampling frequencies, 8-bit or 12-bit resolution and a memory buffer of 15 kbyte. It allows real-time data-acquisition for signals of different nature, in applications that require a large number of sensors, thus it is suited for monitoring of vibrations in Linear Switched Reluctance Actuators (LSRAs. The acquired data allows the full characterization of the LSRA in terms of its response to vibrations of structural origins, and the vibrations and acoustic noise emitted under normal operation. The DSAM can also be used for electrical machine condition monitoring, machine fault diagnosis, structural characterization and monitoring, among other applications.
3. An intelligent sensor array distributed system for vibration analysis and acoustic noise characterization of a linear switched reluctance actuator.
2012-01-01
This paper proposes a distributed system for analysis and monitoring (DSAM) of vibrations and acoustic noise, which consists of an array of intelligent modules, sensor modules, communication bus and a host PC acting as data center. The main advantages of the DSAM are its modularity, scalability, and flexibility for use of different type of sensors/transducers, with analog or digital outputs, and for signals of different nature. Its final cost is also significantly lower than other available commercial solutions. The system is reconfigurable, can operate either with synchronous or asynchronous modes, with programmable sampling frequencies, 8-bit or 12-bit resolution and a memory buffer of 15 kbyte. It allows real-time data-acquisition for signals of different nature, in applications that require a large number of sensors, thus it is suited for monitoring of vibrations in Linear Switched Reluctance Actuators (LSRAs). The acquired data allows the full characterization of the LSRA in terms of its response to vibrations of structural origins, and the vibrations and acoustic noise emitted under normal operation. The DSAM can also be used for electrical machine condition monitoring, machine fault diagnosis, structural characterization and monitoring, among other applications.
4. Optimization of Fixed Microphone Array in High Speed Train Noises Identification Based on Far-Field Acoustic Holography
Rujia Wang
2017-01-01
Full Text Available Acoustical holography has been widely applied for noise sources location and sound field measurement. Performance of the microphones array directly determines the sound source recognition method. Therefore, research is very important to the performance of the microphone array, its array of applications, selection, and how to design instructive. In this paper, based on acoustic holography moving sound source identification theory, the optimization method is applied in design of the microphone array, we select the main side lobe ratio and the main lobe area as the optimization objective function and then put the optimization method use in the sound source identification based on holography, and finally we designed this paper to optimize microphone array and compare the original array of equally spaced array with optimization results; by analyzing the optimization results and objectives, we get that the array can be achieved which is optimized not only to reduce the microphone but also to change objective function results, while improving the far-field acoustic holography resolving effect. Validation experiments have showed that the optimization method is suitable for high speed trains sound source identification microphone array optimization.
5. Core Noise: Implications of Emerging N+3 Designs and Acoustic Technology Needs
Hultgren, Lennart S.
2011-01-01
This presentation is a summary of the core-noise implications of NASA's primary N+3 aircraft concepts. These concepts are the MIT/P&W D8.5 Double Bubble design, the Boeing/GE SUGAR Volt hybrid gas-turbine/electric engine concept, the NASA N3-X Turboelectric Distributed Propulsion aircraft, and the NASA TBW-XN Truss-Braced Wing concept. The first two are future concepts for the Boeing 737/Airbus A320 US transcontinental mission of 180 passengers and a maximum range of 3000 nm. The last two are future concepts for the Boeing 777 transpacific mission of 350 passengers and a 7500 nm range. Sections of the presentation cover: turbofan design trends on the N+1.5 time frame and the already emerging importance of core noise; the NASA N+3 concepts and associated core-noise challenges; the historical trends for the engine bypass ratio (BPR), overall pressure ratio (OPR), and combustor exit temperature; and brief discussion of a noise research roadmap being developed to address the core-noise challenges identified for the N+3 concepts. The N+3 conceptual aircraft have (i) ultra-high bypass ratios, in the rage of 18 - 30, accomplished by either having a small-size, high-power-density core, an hybrid design which allows for an increased fan size, or by utilizing a turboelectric distributed propulsion design; and (ii) very high OPR in the 50 - 70 range. These trends will elevate the overall importance of turbomachinery core noise. The N+3 conceptual designs specify the need for the development and application of advanced liners and passive and active control strategies to reduce the core noise. Current engineering prediction of core noise uses semi-empirical methods based on older turbofan engines, with (at best) updates for more recent designs. The models have not seen the same level of development and maturity as those for fan and jet noise and are grossly inadequate for the designs considered for the N+3 time frame. An aggressive program for the development of updated noise
6. Acoustic tags on wild harbour porpoises reveal context-specific reactions to ship noise
Teilmann, Jonas; Wisniewska, Danuta Maria; Johnson, Mark
While cetacean auditory systems have evolved to cope with underwater noise from natural sources, there is a growing concern that anthropogenic noise may disrupt the behavior, impair the hearing or compromise the general health of cetaceans. Evaluation of the effect of anthropogenic sounds...
7. Changes in distortion product oto-acoustic emissions after exposure to continuous and impulsive noise
de Toro, Miguel Angel Aranda; Ordoñez, Rodrigo Pizarro; Hammershøi, Dorte
2012-01-01
and legislation correlates to a higher risk of hearing damage. Subjects were exposed to two types of binaural recordings consisting of a continuous broad-band noise-exposure normalized to LEX,8h = 80 dBA and the interaction of the previous stimulus with a noise of impulsive character normalized to LEX,8h = 75 + 5...
8. Changes in distortion product oto-acoustic emissions after exposure to continuous and impulsive noise
de Toro, Miguel Angel Aranda; Ordoñez, Rodrigo Pizarro; Hammershøi, Dorte
2012-01-01
and legislation correlates to a higher risk of hearing damage. Subjects were exposed to two types of binaural recordings consisting of a continuous broad-band noise-exposure normalized to LEX,8h = 80~dB and the interaction of the previous stimulus with a noise of impulsive character normalized to LEX,8h = 75 + 5...
9. 对MRI系统噪声的法规要求及测试方法%Regulatory Requirements and Testing Methods of MRI Acoustic Noise
薛廷强; 裴茂增; 何超明
2014-01-01
MRI扫描过程中梯度线圈受变化的洛伦茨力作用会产生振动并发出噪声。过高的噪声除了会引起病人不适外，还可能影响成像效果。本文总结并分析了MRI噪声相关的法规要求及相应测试方法，旨在为相关人员客观评估MRI系统的声学噪声特性，确保系统安全，测试相应降噪措施提供参考。%Gradient coil which is subjected to a variational Lorentz force during MRI scanning can cause gradient coil vibration and then produce acoustic noise. Exorbitant acoustic noise can cause discomfort for patients, and also can affect imaging quality. This paper summarized and analyzed the regulatory requirements and corresponding testing methods of MRI acoustic noise in order to provide reference information for relevant staff to objectively evaluate acoustic noise features of MRI system to ensure system safety and test noise reduction measures.
10. A note on the acoustic-phonetic characteristics of non-native English vowels produced in noise
Li, Chi-Nin; Munro, Murray J.
2003-10-01
The Lombard reflex occurs when people unconsciously raise their vocal levels in the presence of loud background noise. Previous work has established that utterances produced in noisy environments exhibit increases in vowel duration and fundamental frequency (F0), and a shift in formant center frequencies for F1 and F2. Most studies of the Lombard reflex have been conducted with native speakers; research with second-language speakers is much less common. The present study examined the effects of the Lombard reflex on foreign-accented English vowel productions. Seven female Cantonese speakers and a comparison group of English speakers were recorded producing three vowels (/i u a/) in /bVt/ context in quiet and in 70 dB of masking noise. Vowel durations, F0, and the first two formants for each of the three vowels were measured. Analyses revealed that vowel durations and F0 were greater in the vowels produced in noise than those produced in quiet in most cases. First formants, but not F2, were consistently higher in Lombard speech than in normal speech. The findings suggest that non-native English speakers exhibit acoustic-phonetic patterns similar to those of native speakers when producing English vowels in noisy conditions.
11. On Acoustic Feedback Cancellation Using Probe Noise in Multiple-Microphone and Single-Loudspeaker Systems
Guo, Meng; Elmedyb, Thomas Bo; Jensen, Søren Holdt;
2012-01-01
of the adaptive estimation is significantly decreased when keeping the steady-state error unchanged. The goal of this work is to derive analytic expressions for the system behavior such as convergence rate and steady-state error for a multiple-microphone and single-loudspeaker audio system, where the acoustic...
12. Nonlinear Acoustics in a Dispersive Continuum: Random Waves, Radiation Pressure, and Quantum Noise.
1983-03-01
Karpman , Nonlinear Waves in Dispersive Media, Pergamon Press, New York, 1975, p. 76. 26. R. Beyers, Nonlinear Acoustics, U.S. Government Printing...20301 U. S. Army Research nffice 2 copies Box 12211 Research Triangle Park tlorth Carolina 27709 Defense Technical Information Center 12 copies Cameron
13. Numerical Simulation of Acoustic Wave Propagation to Assess Noise-Induced Damage to Human Hearing
2009-07-19
there. 3.2 Two-stage acoustic integral-equation solver Conventional Lippmann- Schwinger integral equations, when applied to high- contrast problems...an inhomogeneous body by means of the volumetric integral equations (the Lippmann- Schwinger equations). In this case, the fact that only a small
14. System for Acquisition and Analysis of Energy-Based Acoustic Data for Rocket Noise Project
National Aeronautics and Space Administration — Accurate estimates of the vibroacoustic loading placed on space vehicles and payloads during launch require knowledge of the rocket noise source properties. Given...
15. Acoustic evaluation of a novel swept-rotor fan. [noise reduction in turbofan engines
Lucas, J. G.; Woodward, R. P.; Mackinnon, M. J.
1978-01-01
Inlet noise and aerodynamic performance are presented for a high tip speed fan designed with rotor blade leading edge sweep that gives a subsonic component of inlet Mach number normal to the edge at all radii. The intent of the design was to minimize the generation of rotor leading edge shock waves thereby minimizing multiple pure tone noise. Sound power level and spectral comparisons are made with several high-speed fans of conventional design. Results show multiple pure tone noise at levels below those of some of the other fans and this noise was initiated at a higher tip speed. Aerodynamic performance of the fan did not meet design goals for this first build which applied conventional design procedures to the swept fan geometry.
16. Acoustic analysis of aft noise reduction techniques measured on a subsonic tip speed 50.8 cm (twenty inch) diameter fan. [quiet engine program
Stimpert, D. L.; Clemons, A.
1977-01-01
Sound data which were obtained during tests of a 50.8 cm diameter, subsonic tip speed, low pressure ratio fan were analyzed. The test matrix was divided into two major investigations: (1) source noise reduction techniques; and (2) aft duct noise reduction with acoustic treatment. Source noise reduction techniques were investigated which include minimizing second harmonic noise by varying vane/blade ratio, variation in spacing, and lowering the Mach number through the vane row to lower fan broadband noise. Treatment in the aft duct which includes flow noise effects, faceplate porosity, rotor OGV treatment, slant cell treatment, and splitter simulation with variable depth on the outer wall and constant thickness treatment on the inner wall was investigated. Variable boundary conditions such as variation in treatment panel thickness and orientation, and mixed porosity combined with variable thickness were examined. Significant results are reported.
17. A Robust Approach For Acoustic Noise Suppression In Speech Using ANFIS
Martinek, Radek; Kelnar, Michal; Vanus, Jan; Bilik, Petr; Zidek, Jan
2015-11-01
18. [Comparision of forced expiratory time, recorded by two spirometers with flow sensors of various types, and acoustic duration of tracheal forced expiratory noises].
Malaeva, V V; Pochekutova, I A; Korenbaum, V I
2015-01-01
In the sample of 44 volunteers forced expiratory time values obtained in spirometers, equipped with flow sensor of Lilly type and turbine flow sensor, and acoustic duration of tracheal forced expiratory noises are compared. It is shown that spirometric forced expiratory time is dependent on flow sensor type. Therefore it can't be used in diagnostic aims.
19. Acoustic Noise Test Report for the U.S. Department of Energy 1.5-Megawatt Wind Turbine
Roadman, Jason [National Renewable Energy Lab. (NREL), Golden, CO (United States); Huskey, Arlinda [National Renewable Energy Lab. (NREL), Golden, CO (United States)
2015-07-01
A series of tests were conducted to characterize the baseline properties and performance of the U.S. Department of Energy (DOE) 1.5-megawatt wind turbine (DOE 1.5) to enable research model development and quantify the effects of future turbine research modifications. The DOE 1.5 is built on the platform of GE's 1.5-MW SLE commercial wind turbine model. It was installed in a nonstandard configuration at the NWTC with the objective of supporting DOE Wind Program research initiatives such as A2e. Therefore, the test results may not represent the performance capabilities of other GE 1.5-MW SLE turbines. The acoustic noise test documented in this report is one of a series of tests carried out to establish a performance baseline for the DOE 1.5 in the NWTC inflow environment.
20. Duct wall impedance control as an advanced concept for acoustic suppression enhancement. [engine noise reduction
Dean, P. D.
1978-01-01
A systems concept procedure is described for the optimization of acoustic duct liner design for both uniform and multisegment types. The concept was implemented by the use of a double reverberant chamber flow duct facility coupled with sophisticated computer control and acoustic analysis systems. The optimization procedure for liner insertion loss was based on the concept of variable liner impedance produced by bias air flow through a multilayer, resonant cavity liner. A multiple microphone technique for in situ wall impedance measurements was used and successfully adapted to produce automated measurements for all liner configurations tested. The complete validation of the systems concept was prevented by the inability to optimize the insertion loss using bias flow induced wall impedance changes. This inability appeared to be a direct function of the presence of a higher order energy carrying modes which were not influenced significantly by the wall impedance changes.
1. Computational Acoustics of Noise Propagation in Fluids - Finite and Boundary Element Methods
Marburg, Steffen
2008-01-01
Among numerical methods applied in acoustics, the Finite Element Method (FEM) is normally favored for interior problems whereas the Boundary Element Method (BEM) is quite popular for exterior ones. That is why this valuable reference provides a complete survey of methods for computational acoustics, namely FEM and BEM. It demonstrates that both methods can be effectively used in the complementary cases. The chapters by well-known authors are evenly balanced: 10 chapters on FEM and 10 on BEM. An initial conceptual chapter describes the derivation of the wave equation and supplies a unified approach to FEM and BEM for the harmonic case. A categorization of the remaining chapters and a personal outlook complete this introduction. In what follows, both FEM and BEM are discussed in the context of very different problems. Firstly, this comprises numerical issues, e.g. convergence, multi-frequency solutions and highly efficient methods; and secondly, solutions techniques for the particular difficulties that arise wi...
2. Possibilities of Railway Development in Lithuania: the Analysis of Regulations for Railway Design in the Aspect of Reduction of Acoustic Noise
Aja Tumavičė
2016-02-01
Full Text Available All over the world railways are of the least-polluting vehicles, and they became increasingly popular. However, the noise emission from railway infrastructure is the most problematic issue, especially at the development planning stage. This article presents analysis of Lithuanian regulations for railway design in the aspect of reduction of acoustic noise. It analyses regulations, which are mandatory for Lithuanian railway designers and builders. In addition, the overview of regulations’provisions, which are related to noise mitigation measures, are presented.
3. Thin broadband noise absorption through acoustic reactance control by electro-mechanical coupling without sensor.
Zhang, Yumin; Chan, Yum-Ji; Huang, Lixi
2014-05-01
Broadband noise with profound low-frequency profile is prevalent and difficult to be controlled mechanically. This study demonstrates effective broadband sound absorption by reducing the mechanical reactance of a loudspeaker using a shunt circuit through electro-mechanical coupling, which induces reactance with different signs from that of loudspeaker. An RLC shunt circuit is connected to the moving coil to provide an electrically induced mechanical impedance which counters the cavity stiffness at low frequencies and reduces the system inertia above the resonance frequency. A sound absorption coefficient well above 0.5 is demonstrated across frequencies between 150 and 1200 Hz. The performance of the proposed device is superior to existing passive absorbers of the same depth (60 mm), which has lower frequency limits of around 300 Hz. A passive noise absorber is further proposed by paralleling a micro-perforated panel with shunted loudspeaker which shows potentials in absorbing band-limit impulse noise.
4. Combined acoustical and visual performance of noise barriers in mitigating the environmental impact of motorways.
Jiang, Like; Kang, Jian
2016-02-01
This study investigated the overall performance of noise barriers in mitigating environmental impact of motorways, taking into consideration their effects on reducing noise and visual intrusions of moving traffic, but also potentially inducing visual impact themselves. A laboratory experiment was carried out, using computer-visualised video scenes and motorway traffic noise recordings to present experimental scenarios covering two traffic levels, two distances of receiver to road, two types of background landscape, and five barrier conditions including motorway only, motorway with tree belt, motorways with 3 m timber barrier, 5m timber barrier, and 5m transparent barrier. Responses from 30 participants of university students were gathered and perceived barrier performance analysed. The results show that noise barriers were always beneficial in mitigating environmental impact of motorways, or made no significant changes in environmental quality when the impact of motorways was low. Overall, barriers only offered similar mitigation effect as compared to tree belt, but showed some potential to be more advantageous when traffic level went high. 5m timber barrier tended to perform better than the 3m one at the distance of 300 m but not at 100 m possibly due to its negative visual effect when getting closer. The transparent barrier did not perform much differently from the timber barriers but tended to be the least effective in most scenarios. Some low positive correlations were found between aesthetic preference for barriers and environmental impact reduction by the barriers.
5. 声学建模预测降噪效果%Prediction of Noise Reduction Effect with Acoustic Modeling
郝娇; 翟国庆
2013-01-01
某星级酒店配套冷却塔噪声对所在5A级风景区声环境影响较大，将冷却塔视为二个侧面进风口、二个顶部排风口共4个面声源，在确定4个面声源的相对源强（A计权声功率级）大小情况下，采用Cadna/A软件进行声学建模，通过与实测值比较，最终校验确定4个面声源绝对源强，科学预测冷却塔正常运行工况下，上述4个面声源对厂界及界外敏感建筑处的噪声贡献值。在此基础上，对照降噪目标，并结合景区声景观要求，通过Cadna/A预测降噪效果，工程实施后降噪效果实测值与预测值基本一致。%The noise of cooling tower influenced much bigger to the sound environment of 5 A level scenic spot. The modeling of acoustic was developed by Cadna/A to predict the noise contribution value of 2 air intakes and 2 air outlets which was regarded as 4 area sources when cooling towers were working. To define the absolute A-weighted sound power level according to the relative value by comparing the measured and predicted value. Based on it, to design and optimize noise reduction projects. After the treatment, the measured and predicted value showing no difference, which meet the required environment limit and soudscape.
6. Effects of Tidal Turbine Noise on Fish Task 2.1.3.2: Effects on Aquatic Organisms: Acoustics/Noise - Fiscal Year 2011 - Progress Report - Environmental Effects of Marine and Hydrokinetic Energy
Halvorsen, Michele B.; Carlson, Thomas J.; Copping, Andrea E.
2011-09-30
Naturally spawning stocks of Chinook salmon (Oncorhynchus tshawytscha) that utilize Puget Sound are listed as threatened (http://www.nwr.noaa.gov/ESA-Salmon-Listings/Salmon-Populations/ Chinook/CKPUG.cfm). Plans exist for prototype tidal turbines to be deployed into their habitat. Noise is known to affect fish in many ways, such as causing a threshold shift in auditory sensitivity or tissue damage. The characteristics of noise, its spectra and level, are important factors that influence the potential for the noise to injure fish. For example, the frequency range of the tidal turbine noise includes the audiogram (frequency range of hearing) of most fish. This study (Effects on Aquatic Organisms, Subtask 2.1.3.2: Acoustics) was performed during FY 2011 to determine if noise generated by a 6-m-diameter open-hydro turbine might affect juvenile Chinook salmon hearing or cause barotrauma. After they were exposed to simulated tidal turbine noise, the hearing of juvenile Chinook salmon was measured and necropsies performed to check for tissue damage. Experimental groups were (1) noise exposed, (2) control (the same handling as treatment fish but without exposure to tidal turbine noise), and (3) baseline (never handled). Preliminary results indicate that low levels of tissue damage may have occurred but that there were no effects of noise exposure on the auditory systems of the test fish.
7. Vessel Noise Affects Beaked Whale Behavior: Results of a Dedicated Acoustic Response Study
2012-08-01
strict accordance with the US Animal Welfare Act following the relevant recommendations of the Guide for the Care and Use of Laboratory Animals of the...Institutional Animal Care and Use Committees and the Animal Welfare and the Ethics Committee of the University of St Andrews. 2.2 Background The exposure...Washington DC: National Academy Press. 192 p. 5. Nowacek DP, Thorne LH, Johnston DW, Tyack PL (2007) Responses of cetaceans to anthropogenic noise. Mammal Rev
8. 大口径天然气管道音波信号的降噪方法%Noise Reduction for Large-Diameter Gas Pipeline Acoustic Signals
梁伟; 张来斌; 郭磊
2012-01-01
According to the characteristics of nonlinear system when large-diameter gas pipeline runs, lo-cal-projective noise reduction method is used to reduce the strong background noises mixed in acoustic signals. The theoretical basis, the algorithm steps as well as the mathematical model of local-projective noise reduction method are introduced. Furthermore, the key parameters of algorithm, embedding dimension and delay time, are described respectively and calculated by corresponding methods. The original acoustic signals of three different field operation conditions are de-noised, and the results show that the signal-to-noise ratio is increased by 20. 7～38. 2 dB, which illustrates the effective and practical local-projective noise reduction method can realize correct separation of acoustic feature signals from noises.%针对大口径天然气管道运行的非线性系统的特点,利用局部投影降噪方法对高含噪声的音波信号进行降噪处理.介绍了局部投影降噪方法的理论基础、算法步骤和数学模型,对该算法中的关键参数嵌入维数和时间延迟分别进行了说明,并用相应的方法进行求解计算.对现场3种不同工况的原始音波数据进行降噪分析,结果显示信噪比提高了20.7～38.2 dB,说明了局部投影降噪方法对音波信号降噪的有效性和实用性,能实现噪声与特征信号的正确分离.
9. Acoustic emission noise from sodium vapour bubble collapsing: detection, interpretation, modelling and simulation
Dentico, G.; Pacilio, V.; Papalia, B.; Taglienti, S.; Tosi, V.
1982-01-01
Sodium vapour bubble collapsing is detected by means of piezoelectric accelorometers coupled to the test section via short waveguides. The output analog signal is processed by transforming it into a time series of pulses through the setting of an amplitude threshold and the shaping of a standard pulse (denominated 'event') every time the signal crosses that border. The number of events is counted in adjacent and equal time duration samples and the waiting time distribution between contiguous events is measured. Up to the moment, six kinetic properties have been found for the mentioned time series. They help in setting a stochastic model in which the subministration of energy into a liquid sodium medium induces the formation of vapour bubbles and their consequent collapsing delivers acoustic pulses. Finally, a simulation procedure is carried out: a Polya's urn model is adopted for simulating event sequences with a priori established requisites.
10. Resizing buffer rods for ultrasound testing of food products with acoustic noise considerations.
García-Álvarez, Javier; García-Hernández, Miguel J; Novoa-Díaz, Daniel F; Turó Peroy, Antoni; Chávez Domínguez, Juan Antonio; Salazar Soler, Jordi
2013-01-01
Buffer rods can be used to perform non-destructive and on-line analysis of food and beverage products. These rods, usually solid cylinders, can be long and heavy for certain applications. In this paper, a resizing analytic procedure is described. Buffer rods designed following this new procedure can be several times shorter than the conventionally designed ones, optimising thus their weight and cost. The signal to noise ratio (SNR) of the resized buffers is also studied in order to determine their practical usability. To this effect, simulations and experiments are conducted using metal and plastic buffer rod materials appropriate for food and beverage testing such as aluminium and polyethylene.
11. Vibro-Acoustic Analysis of Computer Disk Drive Components with Emphasis on Electro-Mechanical Noise Sources.
Lee, Ming-Ran
Vibro-acoustic characteristics of compact electro -mechanical devices are not well understood. This study examines fundamental research issues in this area through the example case of a 3.5" personal computer hard disk drive. In particular, a narrow band mathematical model of the drive has been developed to predict prominent pure tones over the high frequency range (1-6.5 KHz). Through detailed analytical studies, it has been found that the motor torque pulsation of the brushless d.c. motor is the source for this noise problem. Accordingly, a simplified disk drive model consisting of motor driving a single disk is used to investigate key components, with emphasis on the development of new mathematical models to describe the source, path and radiator characteristics. Two different mathematical models have been developed for brushless d.c. motor to predict the torque spectrum associated with invertor switching logic, pulse width modulation control scheme, eccentricity, and magnetic saturation. Frequency contents of predicted variables are identified and matched with measured sound data. Additionally, the Galerkin's method (or modified harmonic balance) is also employed successfully to develop an efficient computational scheme which predicts the Fourier coefficients of torque pulsations directly including various effects associated with inductance harmonics and the fluctuation of rotor angular velocity. For the radiator (annular disk), modal base formulations of sound radiation have been developed by approximating disk eigen-functions. Specifically, the effects of modal coupling and source rotation on radiated sound are investigated. Analytical predictions match well with numerical results obtained by using a boundary element program. New mobility transfer functions (path) are derived to couple the source and radiator formulations in order to construct an overall vibro-acoustic model. Potential areas of further research including experimental validation are discussed.
12. Comparing Intensity Elicited Maximum Reflex Amplitude Between Noise Induced Hearing Loss & Acoustic Trauma at 1 kHz, Contra laterally, and Investigate Relationship Between Amplitude and Hearing Impairment
Dr. Yones Lotfi
2001-05-01
Full Text Available Method and Materials; this cross sectional descriptive and analytic survey was done at Golestan navy hospital in Tehran, between June 1998 and March 1999 on total of 69 male subject (104 ears, 50 acoustic trauma & 54 noise induced H.L between 20 to 40 ears old. Results: The mean acoustic reflex threshold at 1 kHz showed there is no significant difference between two groups. 2- The intensity elicited maximum reflex amplitude at 1 kHz didn;t produce at a significant linear correlation with subjects age and ear canal volume in both groups. 3- The intensity elicited maximum reflex amplitude in NIHL group wasn't shown a significant correlation with ear compliance and gradient. 4- The mean Intensity (SPL elicited maximum reflex amplitude in NIHL group was more than mean intensity (SPL in acoustic trauma group. 5- The mean intensity (SL elicited maximum reflex amplitude in NIHL group was More than mean intensity (SL in acoustic trauma group. Conclusion: Acoustic reflex amplitude is reduced for subjects with NIHL compared with acoustic trauma subjects.
13. Research for Noise Reduction Effect of Different Inlet Acoustic Liner Splices%声衬拼缝对进气道降噪效果影响研究
徐俊伟; 马向东; 周宇穗
2015-01-01
随着商用航空发动机涵道比的增大，风扇噪声已是目前飞机最主要的噪声源之一。通过在进气道内壁安装声学声衬，可以有效降低风扇前传声。针对某型飞机发动机进气道，利用管道模态方法对该进气道不同声衬拼缝宽度和不同声衬拼缝数量进行降噪量计算和分析。计算结果表明，在拼缝数量不变的情况下，随着拼缝宽度的增大，进气道对一阶风扇通过频率噪声的降噪效果逐步下降。在拼缝总宽度不变的情况下，拼缝数目越多，单个拼缝宽度越小，则进气道降噪效果越好。%With the increase of commercial aircraft engine bypass ratio, fan noise becomes one of the main noise sources in aircraft. Acoustic liner installed at the inner wall can reduce forward fan noise effectively. Directed at one aircraft engine inlet, duct mode method is utilized to calculate noise reduction with different acoustic liner widths and different acoustic liner splices. The results show that inlet noise reduction capability to first order blade pass frequency decreases with splice quantity unchanged and width increase. Under the condition of total splice width unchanged, noise reduction capability increases with more splices and single splice width decreases.
14. Lexico-semantic and acoustic-phonetic processes in the perception of noise-vocoded speech: implications for cochlear implantation.
Carolyn eMcGettigan
2014-02-01
Full Text Available Noise-vocoding is a transformation which, when applied to speech, severely reduces spectral resolution and eliminates periodicity, yielding a stimulus that sounds like a harsh whisper (Scott, Blank et al. 2000. This process simulates a cochlear implant, where the activity of many thousand hair cells in the inner ear is replaced by direct stimulation of the auditory nerve by a small number of tonotopically-arranged electrodes. Although a cochlear implant offers a powerful means of restoring some degree of hearing to profoundly deaf individuals, the outcomes for spoken communication are highly variable (Moore and Shannon 2009. Some variability may arise from differences in peripheral representation (e.g. the degree of residual nerve survival but some may reflect differences in higher-order linguistic processing. In order to explore this possibility, we used noise-vocoding to explore speech recognition and perceptual learning in normal-hearing listeners tested across several levels of the linguistic hierarchy: segments (consonants and vowels, single words, and sentences. Listeners improved significantly on all tasks across two test sessions. In the first session, individual differences analyses revealed two independently varying sources of variability: one lexico-semantic in nature and implicating the recognition of words and sentences, and the other an acoustic-phonetic factor associated with words and segments. However, consequent to learning, by the second session there was a more uniform covariance pattern concerning all stimulus types. A further analysis of phonetic feature recognition allowed greater insight into learning-related changes in perception and showed that, surprisingly, participants did not make full use of cues that were preserved in the stimuli (e.g. vowel duration. We discuss these findings in relation cochlear implantation, and suggest auditory training strategies to maximise speech recognition performance in the absence of
15. The use of a global index of acoustic assessment for predicting noise in industrial rooms and optimizing the location of machinery and workstations.
Pleban, Dariusz
2014-01-01
This paper describes the results of a study aimed at developing a tool for optimizing the location of machinery and workstations. A global index of acoustic assessment of machines was developed for this purpose. This index and a genetic algorithm were used in a computer tool for predicting noise emission of machines as well as optimizing the location of machines and workstations in industrial rooms. The results of laboratory and simulation tests demonstrate that the developed global index and the genetic algorithm support measures aimed at noise reduction at workstations.
16. Nonlinear acoustics in a dispersive continuum: Random waves, radiation pressure, and quantum noise
Cabot, M. A.
The nonlinear interaction of sound with sound is studied using dispersive hydrodynamics which derived from a variational principle and the assumption that the internal energy density depends on gradients of the mass density. The attenuation of sound due to nonlinear interaction with a background is calculated and is shown to be sensitive to both the nature of the dispersion and decay bandwidths. The theoretical results are compared to those of low temperature helium experiments. A kinetic equation which described the nonlinear self-inter action of a background is derived. When a Deybe-type cutoff is imposed, a white noise distribution is shown to be a stationary distribution of the kinetic equation. The attenuation and spectrum of decay of a sound wave due to nonlinear interaction with zero point motion is calculated. In one dimension, the dispersive hydrodynamic equations are used to calculate the Langevin and Rayleigh radiation pressures of wave packets and solitary waves.
17. Investigation of acoustic properties of a rigid foam with application to noise reduction in light aircraft
Holmer, C. I.
1972-01-01
A analytic model of sound transmission into an aircraft cabin was developed as well as test procedures which appropriately rank order properties which affect sound transmission. The proposed model agrees well with available data, and reveals that the pertinent properties of an aircraft cabin for sound transmission include: stiffness of cabin walls at low frequencies (as this reflects on impedance of the walls) and cabin wall transmission loss and interior absorption at mid and high frequencies. Below 315 Hz the foam contributes substantially to wall stiffness and sound transmission loss of typical light aircraft cabin construction, and could potentially reduce cabin noise levels by 3-5 db in this frequency range at a cost of about 0:2 lb/sq. ft. of treated cabin area. The foam was found not to have significant sound absorbing properties.
18. Development of nonlinear acoustic propagation analysis tool toward realization of loud noise environment prediction in aeronautics
Kanamori, Masashi, E-mail: [email protected]; Takahashi, Takashi, E-mail: [email protected]; Aoyama, Takashi, E-mail: [email protected] [Japan Aerospace Exploration Agency, 7-44-1, Jindaijihigashi-machi, Chofu, Tokyo (Japan)
2015-10-28
Shown in this paper is an introduction of a prediction tool for the propagation of loud noise with the application to the aeronautics in mind. The tool, named SPnoise, is based on HOWARD approach, which can express almost exact multidimensionality of the diffraction effect at the cost of back scattering. This paper argues, in particular, the prediction of the effect of atmospheric turbulence on sonic boom as one of the important issues in aeronautics. Thanks to the simple and efficient modeling of the atmospheric turbulence, SPnoise successfully re-creates the feature of the effect, which often emerges in the region just behind the front and rear shock waves in the sonic boom signature.
19. Psychophysiological acoustics of indoor sound due to traffic noise during sleep
Tulen, J. H. M.; Kumar, A.; Jurriëns, A. A.
1986-10-01
The relation between the physical characteristics of sound and an individual's perception of its as annoyance is complex and unclear. Sleep disturbance by sound is manifested in the physiological responses to the sound stimuli and the quality of sleep perceived in the morning. Both may result in deterioration of functioning during wakefulness. Therefore, psychophysiological responses to noise during sleep should be studied for the evaluation of the efficacy of sound insulation. Nocturnal sleep and indoor sound level were recorded in the homes of 12 subjects living along a highway with high traffic density. Double glazing sound insulation was used to create two experimental conditions: low insulation and high insulation. Twenty recordings were made per subject, ten recordings in each condition. During the nights with low insulation the quality of sleep was so low that both performance and mood were negatively affected. The enhancement of sound insulation was not effective enough to increase the restorative effects of sleep. The transient and peaky characteristics of traffic sound were also found to result in non-adaptive physiological responses during sleep. Sound insulation did have an effect on noise peak characteristics such as peak level, peak duration and slope. However, the number of sound peaks were found to be the same in both conditions. The relation of these sound peaks detected in the indoor recorded sound level signal to characteristics of passing vehicles was established, indicating that the sound peaks causing the psychophysiological disturbances during sleep were generated by the passing vehicles. Evidence is presented to show that the reduction in sound level is not a good measure of efficacy of sound insulation. The parameters of the sound peaks, as described in this paper, are a better representation of psychophysiological efficacy of sound insulation.
20. Advanced Jet Noise Exhaust Concepts in NASA's N+2 Supersonics Validation Study and the Environmentally Responsible Aviation Project's Upcoming Hybrid Wing Body Acoustics Test
Henderson, Brenda S.; Doty, Mike
2012-01-01
Acoustic and flow-field experiments were conducted on exhaust concepts for the next generation supersonic, commercial aircraft. The concepts were developed by Lockheed Martin (LM), Rolls-Royce Liberty Works (RRLW), and General Electric Global Research (GEGR) as part of an N+2 (next generation forward) aircraft system study initiated by the Supersonics Project in NASA s Fundamental Aeronautics Program. The experiments were conducted in the Aero-Acoustic Propulsion Laboratory at the NASA Glenn Research Center. The exhaust concepts presented here utilized lobed-mixers and ejectors. A powered third-stream was implemented to improve ejector acoustic performance. One concept was found to produce stagnant flow within the ejector and the other produced discrete-frequency tones (due to flow separations within the model) that degraded the acoustic performance of the exhaust concept. NASA's Environmentally Responsible Aviation (ERA) Project has been investigating a Hybrid Wing Body (HWB) aircraft as a possible configuration for meeting N+2 system level goals for noise, emissions, and fuel burn. A recently completed NRA led by Boeing Research and Technology resulted in a full-scale aircraft design and wind tunnel model. This model will be tested acoustically in NASA Langley's 14-by 22-Foot Subsonic Tunnel and will include dual jet engine simulators and broadband engine noise simulators as part of the test campaign. The objectives of the test are to characterize the system level noise, quantify the effects of shielding, and generate a valuable database for prediction method development. Further details of the test and various component preparations are described.
1. Acoustics. Noise emitted by machinery and equipment. Measurement of emission sound pressure levels at a work station and at other specified positions. Engineering method in an essentially free field over a reflecting plane
British Standards Institution. London
1996-01-01
Acoustics. Noise emitted by machinery and equipment. Measurement of emission sound pressure levels at a work station and at other specified positions. Engineering method in an essentially free field over a reflecting plane
2. Control of low-frequency noise for piping systems via the design of coupled band gap of acoustic metamaterials
Li, Yanfei; Shen, Huijie; Zhang, Linke; Su, Yongsheng; Yu, Dianlong
2016-07-01
Acoustic wave propagation and sound transmission in a metamaterial-based piping system with Helmholtz resonator (HR) attached periodically are studied. A transfer matrix method is developed to conduct the investigation. Calculational results show that the introduction of periodic HRs in the piping system could generate a band gap (BG) near the resonant frequency of the HR, such that the bandwidth and the attenuation effect of HR improved notably. Bragg type gaps are also exist in the system due to the systematic periodicity. By plotting the BG as functions of HR parameters, the effect of resonator parameters on the BG behavior, including bandwidth, location and attenuation performance, etc., is examined. It is found that Bragg-type gap would interplay with the resonant-type gap under some special situations, thereby giving rise to a super-wide coupled gap. Further, explicit formulation for BG exact coupling is extracted and some key parameters on modulating the width and the attenuation coefficient of coupled gaps are investigated. The coupled gap can be located to any frequency range as one concerned, thus rendering the low-frequency noise control feasible in a broad band range.
3. Noise suppression in curved glass shells using macro-fiber-composite actuators studied by the means of digital holography and acoustic measurements
P. Mokrý
2015-02-01
Full Text Available The paper presents methods and experimental results of the semi-active control of noise transmission in a curved glass shell with attached piezoelectric macro fiber composite (MFC actuators. The semi-active noise control is achieved via active elasticity control of piezoelectric actuators by connecting them to an active electric shunt circuit that has a negative effective capacitance. Using this approach, it is possible to suppress the vibration of the glass shell in the normal direction with respect to its surface and to increase the acoustic transmission loss of the piezoelectric MFC-glass composite structure. The effect of the MFC actuators connected to the negative capacitance shunt circuit on the surface distribution of the normal vibration amplitude is studied using frequency-shifted digital holography (FSDH. The principle of the used FSDH method is described in the paper. The frequency dependence of the acoustic transmission loss through the piezoelectric MFC-glass composite structure is estimated using measurements of the specific acoustic impedance of the curved glass shell. The specific acoustic impedance is measured using two microphones and a laser Doppler vibrometer (LDV. The results from the LDV measurements are compared with the FSDH data. The results of the experiments show that using this approach, the acoustic transmission loss in a glass shell can be increased by 36 dB in the frequency range around 247 Hz and by 25 dB in the frequency range around 258 Hz. The experiments indicate that FSDH measurements provide an efficient tool that can be used for fast and accurate measurements of the acoustic transmission loss in large planar structures.
4. Data analysis results of the second sea trial of ambient noise imaging with acoustic lens in 2014: Two-dimensional target images affected by direction of field of view and spatial noise distribution
Mori, Kazuyoshi; Ogasawara, Hanako; Tsuchiya, Takenobu; Endoh, Nobuyuki
2016-07-01
An aspherical lens with an aperture diameter of 1.0 m has been designed and fabricated to develop a prototype system for ambient noise imaging (ANI). A sea trial of silent target detection using the prototype ANI system was conducted under only natural ocean ambient noise at Uchiura Bay in November 2010. It was verified that targets are successfully detected under natural ocean ambient noise, mainly generated by snapping shrimps. Recently, we have built a second prototype ANI system using an acoustic lens with a two-dimensional (2D) receiver array with 127 elements corresponding to a field of view (FOV) spanning 15° horizontally by 9° vertically. In this study, we investigated the effects of the direction of the FOV and the spatial noise distribution on the 2D target image obtained by ANI. Here, the noise sources in front of the target are called “front light”, and those at the rear of the target are called “back light”. The second sea trial was conducted to image targets arranged in the FOV and measure the positions of noise sources at Uchiura Bay in November 10-14, 2014. For front light, the pixel values in the on-target directions were greater than those in other directions owing to the dominant target scatterings. Reversely, for back light, the pixel values in the on-target directions were lower than those in other directions owing to the dominant direct noises such as “silhouette”.
5. 声屏障声学设计与计算机仿真应用%Acoustic Design of Sound Barriers and Simulation of Their Noise Control Performance
陈永光; 袁启慧; 蔡伟明; 郑佰平
2013-01-01
In order to analyze the acoustic design process of sound barriers, survey analysis of traffic noise in the region around the residential buildings adjacent to an avenue was conducted. Based on the data obtained, three preliminary designs of sound insulation reflective barriers with different top structures were done for this region. To verify the result, acoustic software of Virtual. Lab Acoustic was applied to simulate the noise control performance of the three sound barriers. The simulation results show that the design of the vertical sound barrier can meet the practical noise reduction requirements effectively.%通过对重庆市某道路某处居民楼所存在的噪声污染情况进行实际监测，根据声屏障声学设计的步骤设计出适合该区域的三个不同顶部造型的声屏障，采用声学软件Virtual. Lab Acoustic对三种声屏障的降噪效果进行模拟，对模拟结果进行分析；确认直立型声屏障的设计可满足要求。
6. Effects of scanner acoustic noise on intrinsic brain activity during auditory stimulation
Yakunina, Natalia [Kangwon National University, Institute of Medical Science, School of Medicine, Chuncheon (Korea, Republic of); Kangwon National University Hospital, Neuroscience Research Institute, Chuncheon (Korea, Republic of); Kang, Eun Kyoung [Kangwon National University Hospital, Department of Rehabilitation Medicine, Chuncheon (Korea, Republic of); Kim, Tae Su [Kangwon National University Hospital, Department of Otolaryngology, Chuncheon (Korea, Republic of); Kangwon National University, School of Medicine, Department of Otolaryngology, Chuncheon (Korea, Republic of); Min, Ji-Hoon [University of Michigan, Department of Biopsychology, Cognition, and Neuroscience, Ann Arbor, MI (United States); Kim, Sam Soo [Kangwon National University Hospital, Neuroscience Research Institute, Chuncheon (Korea, Republic of); Kangwon National University, School of Medicine, Department of Radiology, Chuncheon (Korea, Republic of); Nam, Eui-Cheol [Kangwon National University Hospital, Neuroscience Research Institute, Chuncheon (Korea, Republic of); Kangwon National University, School of Medicine, Department of Otolaryngology, Chuncheon (Korea, Republic of)
2015-10-15
Although the effects of scanner background noise (SBN) during functional magnetic resonance imaging (fMRI) have been extensively investigated for the brain regions involved in auditory processing, its impact on other types of intrinsic brain activity has largely been neglected. The present study evaluated the influence of SBN on a number of intrinsic connectivity networks (ICNs) during auditory stimulation by comparing the results obtained using sparse temporal acquisition (STA) with those using continuous acquisition (CA). Fourteen healthy subjects were presented with classical music pieces in a block paradigm during two sessions of STA and CA. A volume-matched CA dataset (CAm) was generated by subsampling the CA dataset to temporally match it with the STA data. Independent component analysis was performed on the concatenated STA-CAm datasets, and voxel data, time courses, power spectra, and functional connectivity were compared. The ICA revealed 19 ICNs; the auditory, default mode, salience, and frontoparietal networks showed greater activity in the STA. The spectral peaks in 17 networks corresponded to the stimulation cycles in the STA, while only five networks displayed this correspondence in the CA. The dorsal default mode and salience networks exhibited stronger correlations with the stimulus waveform in the STA. SBN appeared to influence not only the areas of auditory response but also the majority of other ICNs, including attention and sensory networks. Therefore, SBN should be regarded as a serious nuisance factor during fMRI studies investigating intrinsic brain activity under external stimulation or task loads. (orig.)
7. Acoustic and Laser Doppler Anemometer Results for Confluent and 12-Lobed E(exp 3) Mixer Exhaust Systems for Subsonic Jet Noise Reduction
Salikuddin, M.; Babbit, R. R.; Shin, H.; Wisler, S.; Janardan, B. A.; Majjigi, R. K.; Bridges, James (Technical Monitor)
2002-01-01
8. Study of Harmonics-to-Noise Ratio and Critical-Band Energy Spectrum of Speech as Acoustic Indicators of Laryngeal and Voice Pathology
Cholayya Niranjan U
2007-01-01
Full Text Available Acoustic analysis of speech signals is a noninvasive technique that has been proved to be an effective tool for the objective support of vocal and voice disease screening. In the present study acoustic analysis of sustained vowels is considered. A simple -means nearest neighbor classifier is designed to test the efficacy of a harmonics-to-noise ratio (HNR measure and the critical-band energy spectrum of the voiced speech signal as tools for the detection of laryngeal pathologies. It groups the given voice signal sample into pathologic and normal. The voiced speech signal is decomposed into harmonic and noise components using an iterative signal extrapolation algorithm. The HNRs at four different frequency bands are estimated and used as features. Voiced speech is also filtered with 21 critical-bandpass filters that mimic the human auditory neurons. Normalized energies of these filter outputs are used as another set of features. The results obtained have shown that the HNR and the critical-band energy spectrum can be used to correlate laryngeal pathology and voice alteration, using previously classified voice samples. This method could be an additional acoustic indicator that supplements the clinical diagnostic features for voice evaluation.
9. Study of Harmonics-to-Noise Ratio and Critical-Band Energy Spectrum of Speech as Acoustic Indicators of Laryngeal and Voice Pathology
Niranjan U. Cholayya
2007-01-01
Full Text Available Acoustic analysis of speech signals is a noninvasive technique that has been proved to be an effective tool for the objective support of vocal and voice disease screening. In the present study acoustic analysis of sustained vowels is considered. A simple k-means nearest neighbor classifier is designed to test the efficacy of a harmonics-to-noise ratio (HNR measure and the critical-band energy spectrum of the voiced speech signal as tools for the detection of laryngeal pathologies. It groups the given voice signal sample into pathologic and normal. The voiced speech signal is decomposed into harmonic and noise components using an iterative signal extrapolation algorithm. The HNRs at four different frequency bands are estimated and used as features. Voiced speech is also filtered with 21 critical-bandpass filters that mimic the human auditory neurons. Normalized energies of these filter outputs are used as another set of features. The results obtained have shown that the HNR and the critical-band energy spectrum can be used to correlate laryngeal pathology and voice alteration, using previously classified voice samples. This method could be an additional acoustic indicator that supplements the clinical diagnostic features for voice evaluation.
10. Application of an Aligned and Unaligned Signal Processing Technique to Investigate Tones and Broadband Noise in Fan and Contra-Rotating Open Rotor Acoustic Spectra
Miles, Jeffrey Hilton; Hultgren, Lennart S.
2015-01-01
The study of noise from a two-shaft contra-rotating open rotor (CROR) is challenging since the shafts are not phase locked in most cases. Consequently, phase averaging of the acoustic data keyed to a single shaft rotation speed is not meaningful. An unaligned spectrum procedure that was developed to estimate a signal coherence threshold and reveal concealed spectral lines in turbofan engine combustion noise is applied to fan and CROR acoustic data in this paper (also available as NASA/TM-2015-218865). The NASA Advanced Air Vehicles Program, Advanced Air Transport Technology Project, Aircraft Noise Reduction Subproject supported the current work. The fan and open rotor data were obtained under previous efforts supported by the NASA Quiet Aircraft Technology (QAT) Project and the NASA Environmentally Responsible Aviation (ERA) Project of the Integrated Systems Research Program in collaboration with GE Aviation, respectively. The overarching goal of the Advanced Air Transport (AATT) Project is to explore and develop technologies and concepts to revolutionize the energy efficiency and environmental compatibility of fixed wing transport aircrafts. These technological solutions are critical in reducing the impact of aviation on the environment even as this industry and the corresponding global transportation system continue to grow.
11. 发动机声激励下的车内高频噪声分析%Vehicle Interior High Frequency Noise under Engine Acoustic Excitation
杜爱民; 邵长慧; 邵建旺; 魏娜
2016-01-01
In order to research the vehicle interior high frequency noise and the performance of sound package under the engine acoustic excitation ,the statistical energy analysis and sound package models were built with VA One software .Both the power-based noise reduction test and the engine noise measurement were conducted to verify the accuracy of vehicle model .The cowl panel and floor were identified to be the main noise transfer paths according to the energy contribution of driver head and leg a-coustic cavity ,which laid the foundation for the optimization of sound package and the control of vehicle interior noise in the fu-ture .%为研究发动机声激励下中高频噪声和整车声学包隔声性能,在VA One软件中建立整车统计能量分析模型和声学包模型,并进行基于能量的整车隔声量测试和发动机噪声采集试验,验证了整车模型的准确性.通过对驾驶员头部声腔和腿部声腔的输入能量贡献量分析,发现前围和地板是车内噪声的主要传播路径,为后续汽车声学包的优化设计和车内噪声控制提供了帮助.
12. Investigation into the response of the auditory and acoustic communications systems in the Beluga whale (Delphinapterus leucas) of the St. Lawrence River Estuary to noise, using vocal classification
Scheifele, Peter Martin
2003-06-01
Noise pollution has only recently become recognized as a potential danger to marine mammals in general, and to the Beluga Whale (Delphinapterus leucas) in particular. These small gregarious Odontocetes make extensive use of sound for social communication and pod cohesion. The St. Lawrence River Estuary is habitat to a small, critically endangered population of about 700 Beluga whales who congregate in four different sites in its upper estuary. The population is believed to be threatened by the stress of high-intensity, low frequency noise. One way to determine whether noise is having an effect on an animal's auditory ability might be to observe a natural and repeatable response of the auditory and vocal systems to varying noise levels. This can be accomplished by observing changes in animal vocalizations in response to auditory feedback. A response such as this observed in humans and some animals is known as the Lombard Vocal Response, which represents a reaction of the auditory system directly manifested by changes in vocalization level. In this research this population of Beluga Whales was tested to determine whether a vocalization-as-a-function-of-noise phenomenon existed by using Hidden Markhov "classified" vocalizations as targets for acoustical analyses. Correlation and regression analyses indicated that the phenomenon does exist and results of a human subjects experiment along with results from other animal species known to exhibit the response strongly implicate the Lombard Vocal Response in the Beluga.
13. Acoustic imaging system
Kendall, J. M., Jr.
1977-01-01
Tool detects noise sources by scanning sound "scene" and displaying relative location of noise-producing elements in area. System consists of ellipsoidal acoustic mirror and microphone and a display device.
14. Preliminary Work for Modeling the Propellers of an Aircraft as a Noise Source in an Acoustic Boundary Element Analysis
Vlahopoulos, Nickolas; Lyle, Karen H.; Burley, Casey L.
1998-01-01
An algorithm for generating appropriate velocity boundary conditions for an acoustic boundary element analysis from the kinematics of an operating propeller is presented. It constitutes the initial phase of Integrating sophisticated rotorcraft models into a conventional boundary element analysis. Currently, the pressure field is computed by a linear approximation. An initial validation of the developed process was performed by comparing numerical results to test data for the external acoustic pressure on the surface of a tilt-rotor aircraft for one flight condition.
15. Analysis of binary mixtures of aqueous aromatic hydrocarbons with low-phase-noise shear-horizontal surface acoustic wave sensors using multielectrode transducer designs.
Bender, Florian; Mohler, Rachel E; Ricco, Antonio J; Josse, Fabien
2014-11-18
The present work investigates a compact sensor system that provides rapid, real-time, in situ measurements of the identities and concentrations of aromatic hydrocarbons at parts-per-billion concentrations in water through the combined use of kinetic and thermodynamic response parameters. The system uses shear-horizontal surface acoustic wave (SH-SAW) sensors operating directly in the liquid phase. The 103 MHz SAW sensors are coated with thin sorbent polymer films to provide the appropriate limits of detection as well as partial selectivity for the analytes of interest, the BTEX compounds (benzene, toluene, ethylbenzene, and xylenes), which are common indicators of fuel and oil accidental releases in groundwater. Particular emphasis is placed on benzene, a known carcinogen and the most challenging BTEX analyte with regard to both regulated levels and its solubility properties. To demonstrate the identification and quantification of individual compounds in multicomponent aqueous samples, responses to binary mixtures of benzene with toluene as well as ethylbenzene were characterized at concentrations below 1 ppm (1 mg/L). The use of both thermodynamic and kinetic (i.e., steady-state and transient) responses from a single polymer-coated SH-SAW sensor enabled identification and quantification of the two BTEX compounds in binary mixtures in aqueous solution. The signal-to-noise ratio was improved, resulting in lower limits of detection and improved identification at low concentrations, by designing and implementing a type of multielectrode transducer pattern, not previously reported for chemical sensor applications. The design significantly reduces signal distortion and root-mean-square (RMS) phase noise by minimizing acoustic wave reflections from electrode edges, thus enabling limits of detection for BTEX analytes of 9-83 ppb (calculated from RMS noise); concentrations of benzene in water as low as ~100 ppb were measured directly. Reliable quantification of BTEX
16. Long-term, passive exposure to non-traumatic acoustic noise induces neural adaptation in the adult rat medial geniculate body and auditory cortex.
Lau, Condon; Zhang, Jevin W; McPherson, Bradley; Pienkowski, Martin; Wu, Ed X
2015-02-15
Exposure to loud sounds can lead to permanent hearing loss, i.e., the elevation of hearing thresholds. Exposure at more moderate sound pressure levels (SPLs) (non-traumatic and within occupational limits) may not elevate thresholds, but could in the long-term be detrimental to speech intelligibility by altering its spectrotemporal representation in the central auditory system. In support of this, electrophysiological and behavioral changes following long-term, passive (no conditioned learning) exposure at moderate SPLs have recently been observed in adult animals. To assess the potential effects of moderately loud noise on the entire auditory brain, we employed functional magnetic resonance imaging (fMRI) to study noise-exposed adult rats. We find that passive, pulsed broadband noise exposure for two months at 65 dB SPL leads to a decrease of the sound-evoked blood oxygenation level-dependent fMRI signal in the thalamic medial geniculate body (MGB) and in the auditory cortex (AC). This points to the thalamo-cortex as the site of the neural adaptation to the moderately noisy environment. The signal reduction is statistically significant during 10 Hz pulsed acoustic stimulation (MGB: pnoise exposure has a greater effect on the processing of higher pulse rate sounds. This study has enhanced our understanding of functional changes following exposure by mapping changes across the entire auditory brain. These findings have important implications for speech processing, which depends on accurate processing of sounds with a wide spectrum of pulse rates.
17. Acoustic testing of a 1.5 pressure ratio low tip speed fan with a serrated rotor (QEP fan B scale model). [reduction of engine noise
Kazin, S. B.; Paas, J. E.; Minzner, W. R.
1973-01-01
A scale model of the bypass flow region of a 1.5 pressure ratio, single stage, low tip speed fan was tested with a serrated rotor leading edge to determine its effects on noise generation. The serrated rotor was produced by cutting teeth into the leading edge of the nominal rotor blades. The effects of speed and exhaust nozzle area on the scale models noise characteristics were investigated with both the nominal rotor and serrated rotor. Acoustic results indicate the serrations reduced front quadrant PNL's at takeoff power. In particular, the 200 foot (61.0 m) sideline noise was reduced from 3 to 4 PNdb at 40 deg for nominal and large nozzle operation. However, the rear quadrant maximum sideline PNL's were increased 1.5 to 3 PNdb at approach thust and up to 2 PNdb at takeoff thust with these serrated rotor blades. The configuration with the serrated rotor produced the lowest maximum 200 foot (61.0 m) sideline PNL for any given thust when the large nozzle (116% of design area) was employed.
18. Problems in Nonlinear Acoustics: Scattering of Sound by Sound, Parametric Arrays, Focused Sound Beams, and Noncollinear Tone-Noise Interactions
1988-07-01
of Texas at Austin 3(ARL:UT). 3 A. Background The problem of the scattering of sound by sound, as well as the terminology, was introduced3 by Ingard ...Texas at Austin, June 1987. [2] U. Ingard and D. C. Pridmore-Brown, "Scattering of Sound by Sound," J. Acoust. Soc. Am. 28, 367-369 (1956). [3] R. T
19. 泡沫铝层合结构钢球磨煤机隔声罩降噪性能研究%Study on reduction noise properties of foamed aluminum laminated structure acoustical enclosure for ball mill
于英华; 余国军
2012-01-01
In order to explore a new way for reduction noise of ball mill,the view point of using foamed aluminum laminated structure in ball mill acoustical enclosures was put forward based noise properties of ball mill.The laminated structure plate used to ball mills acoustical enclosures was designed,reduction noise properties of it were studied by theoretical analysis and test.The results show that the new ball mill acoustical enclosures can improve the reduction noise and environmental protection capabilities of the ball mill acoustical enclosure.%为探索钢球磨煤机的降噪新途径,针对钢球磨煤机噪声的特点,提出将泡沫铝层合结构应用于钢球磨煤机隔声罩中的观点。设计了泡沫铝钢球磨煤机隔声罩板的层合结构,并运用理论分析和实验分析的方法对其降噪性能进行研究。结果表明,用泡沫铝层合结构制造钢球磨煤机隔声罩,可提高隔声罩的降噪性能,并可提高隔声罩环保性能。
20. A research program to reduce interior noise in general aviation airplanes. Design of an acoustic panel test facility
Roskam, J.; Muirhead, V. U.; Smith, H. W.; Henderson, T. D.
1977-01-01
The design, construction, and costs of a test facility for determining the sound transmission loss characteristics of various panels and panel treatments are described. The pressurization system and electronic equipment used in experimental testing are discussed as well as the reliability of the facility and the data gathered. Tests results are compared to pertinent acoustical theories for panel behavior and minor anomalies in the data are examined. A method for predicting panel behavior in the stiffness region is also presented.
1. Conceptual design study of advanced acoustic composite nacelle. [for achieving reductions in community noise and operating expense
Goodall, R. G.; Painter, G. W.
1975-01-01
Conceptual nacelle designs for wide-bodied and for advanced-technology transports were studied with the objective of achieving significant reductions in community noise with minimum penalties in airplane weight, cost, and in operating expense by the application of advanced composite materials to nacelle structure and sound suppression elements. Nacelle concepts using advanced liners, annular splitters, radial splitters, translating centerbody inlets, and mixed-flow nozzles were evaluated and a preferred concept selected. A preliminary design study of the selected concept, a mixed flow nacelle with extended inlet and no splitters, was conducted and the effects on noise, direct operating cost, and return on investment determined.
2. Springer Handbook of Acoustics
Rossing, Thomas D
2007-01-01
Acoustics, the science of sound, has developed into a broad interdisciplinary field encompassing the academic disciplines of physics, engineering, psychology, speech, audiology, music, architecture, physiology, neuroscience, and others. The Springer Handbook of Acoustics is an unparalleled modern handbook reflecting this richly interdisciplinary nature edited by one of the acknowledged masters in the field, Thomas Rossing. Researchers and students benefit from the comprehensive contents spanning: animal acoustics including infrasound and ultrasound, environmental noise control, music and human speech and singing, physiological and psychological acoustics, architectural acoustics, physical and engineering acoustics, signal processing, medical acoustics, and ocean acoustics. This handbook reviews the most important areas of acoustics, with emphasis on current research. The authors of the various chapters are all experts in their fields. Each chapter is richly illustrated with figures and tables. The latest rese...
3. 声学建模和阻尼损失系数对舱室噪声影响的研究%Study on the Influence of the Acoustic Modeling and Damping Coefficients on Cabin Noise
郑律; 朱锐
2014-01-01
文章基于统计能量法（SEA）开展了声学覆盖层敷设位置对舱室噪声的影响研究，探讨了不同损耗因子对舱室噪声的影响，计算对比表明阻尼损失系数发生改变时，声学覆盖层的抑振降噪效果亦将发生改变。%In combination with SEA, this article, based on an analysis of the influence of the laying position of the acoustic layer on cabin noise, studies the influence of different dissipation factors on cabin noise, the re-sults of which indicate that the changes of the damping coefficients have a great effect on the vibration damping and noise reduction of the acoustic layer.
4. Simulation-based conceptual design of an acoustic metamaterial with full band gap using an air-based 1-3 piezoelectric composite for ultrasonic noise control
2017-02-01
This paper aims at proposing a novel type of acoustic metamaterials with complete band gap composed of piezoelectric rods with square array as inclusions embedded in an air background (matrix). A modified plane wave expansion method accompanied with the principles of the Bloch-Floquet method with electromechanical coupling effect and also impedance spectra are used to get a band frequency and to investigate the passband for the selected cut of piezoelectric rods. We investigate both the electromechanical coupling coefficient and mechanical quality factor and their dependency to passband and bandwidth, which depends on both the density and the wave impedance of the matrix and the inclusions (rods). The ratio of the volume of inclusion to the matrix is used to define the fill factor or the so-called inclusion ratio, to introduce the bandwidth as a function of that. Furthermore, the fabrication method is presented in this paper. The results make a suitable foundation for design purposes and may develop an inherently passive ultrasonic noise control. In addition, the results provide the required guidance for a simulation-based design of elastic wave filters or wave guide that might be useful in high-precision mechanical systems operated in certain frequency ranges and switches made of piezoelectric materials; they also propose a novel type of elastic metamaterials, which is independent of the wave direction and has an equal sensitivity in all directions in which it reacts omnidirectionally and mitigates the occupational noise exposure.
5. 基于LabVIEW的微波热声信号采集及消噪处理%Acquisition and De-noising of Microwave-induced Thermo-acoustic Signals Based on LabVIEW
王华; 焦腾; 张杨; 于霄; 路国华; 吕昊; 张华; 薛慧君
2012-01-01
Objective To design a method of multi -channel massive data-recording and de-nosing of thermo-acoustic signals with strong background noise for microwave-induced thermo-acoustic tomography. Methods A program based on LabVIEW was used to resolve the data acquisition and preservation problem. The digital filtering was realized through the mix programming of LabVIEW and C language in order to do the de -noising simulation experiments of the strong background noise in the thermo-acoustic signals. Results The average digital filtering could eliminate efficiently the noise in the microwave-induced thermo-acoustic signals and improve the signal to noise ratio(SNR). Conclusion The de-noising method can be used efficiently for the extraction and elimination of most periodic weak signals. [Chinese M6dicdl Equipment Journal,2012,33(6): 8-10]%目的:研究微波热声成像中多通道的大数据量热声信号的采集保存和消除背景噪声的方法.方法:基于LabVIEW软件编程实现数据的采集与保存,并通过LabVIEW和C语言混合编程实现数字滤波,对热声信号中的强背景噪声进行消噪处理仿真实验.结果:数字平均滤波能够有效消除微波热声信号中的噪声,提高信噪比.结论:该方法可以有效地用于绝大部分具有周期特性的微弱信号提取和消噪处理.
6. Mechanics of underwater noise
Ross, Donald
1976-01-01
Mechanics of Underwater Noise elucidates the basic mechanisms by which noise is generated, transmitted by structures and radiated into the sea. Organized into 10 chapters, this book begins with a description of noise, decibels and levels, significance of spectra, and passive sonar equation. Subsequent chapters discuss sound waves in liquids; acoustic radiation fundamentals; wind-generated ocean ambient noise; vibration isolation and structural damping; and radiation by plate flexural vibrations. Other chapters address cavitation, propeller cavitation noise, radiation by fluctuating-force (dipo
7. Simulated flight acoustic investigation of treated ejector effectiveness on advanced mechanical suppresors for high velocity jet noise reduction
Brausch, J. F.; Motsinger, R. E.; Hoerst, D. J.
1986-01-01
Ten scale-model nozzles were tested in an anechoic free-jet facility to evaluate the acoustic characteristics of a mechanically suppressed inverted-velocity-profile coannular nozzle with an accoustically treated ejector system. The nozzle system used was developed from aerodynamic flow lines evolved in a previous contract, defined to incorporate the restraints imposed by the aerodynamic performance requirements of an Advanced Supersonic Technology/Variable Cycle Engine system through all its mission phases. Accoustic data of 188 test points were obtained, 87 under static and 101 under simulated flight conditions. The tests investigated variables of hardwall ejector application to a coannular nozzle with 20-chute outer annular suppressor, ejector axial positioning, treatment application to ejector and plug surfaces, and treatment design. Laser velocimeter, shadowgraph photograph, aerodynamic static pressure, and temperature measurement were acquired on select models to yield diagnositc information regarding the flow field and aerodynamic performance characteristics of the nozzles.
8. 声学引导风洞高效低噪声风扇设计%The design of the high-performance low-noise fan of the acoustic pilot wind tunnel
屈晓力; 余永生; 廖达雄; 吕金磊
2013-01-01
Arbitrary vortex method is used to design a high-performance low-noise fan for the acoustic pilot wind tunnel.In the design,a more well-distributed axial speed at the outlet of fan system is obtained by regulating the rotating speed distribution,the noise generated by rotor-stator interaction is reduced by matching more reasonable rotor-stator blade number and stator backward-swept angle.According to the results of the fan aerodynamic and acoustic experiments,the efficiency of the high-performance low-noise fan is 83.9％ at its design point,which is an obvious improvement compared with the original fan setting in acoustic pilot wind tunnel(73％),meanwhile,the inlet noise of high-performance low-noise fan is 3dB(A) lower than the inlet noise of original fan,and the outlet noise of high-performance low-noise fan is 2dB(A) lower than the outlet noise of the original fan.The experimental results indicate that arbitrary vortex method has significant advantage in fan aerodynamic and acoustic performances.%运用任意涡风扇设计方法,进行声学引导风洞高效低噪声风扇设计.在设计过程中,通过调整叶片径向旋转系数分布优化叶片出口速度分布,通过合理匹配转子、定子数目及定子后掠角度来改善动静叶的干涉噪声.气动及声学性能试验表明,高效低噪声风扇设计点气动效率达到83.9％,相比引导风洞原风扇效率的73％有了明显的提高；高效低噪声风扇入口及出口噪声分别比原风扇入口及出口噪声低3dB(A)和2dB(A).试验结果成功验证了任意涡设计方法在风扇气动及声学性能上的优越性.
9. Vibro-acoustics
Nilsson, Anders
2015-01-01
This three-volume book gives a thorough and comprehensive presentation of vibration and acoustic theories. Different from traditional textbooks which typically deal with some aspects of either acoustic or vibration problems, it is unique of this book to combine those two correlated subjects together. Moreover, it provides fundamental analysis and mathematical descriptions for several crucial phenomena of Vibro-Acoustics which are quite useful in noise reduction, including how structures are excited, energy flows from an excitation point to a sound radiating surface, and finally how a structure radiates noise to a surrounding fluid. Many measurement results included in the text make the reading interesting and informative. Problems/questions are listed at the end of each chapter and the solutions are provided. This will help the readers to understand the topics of Vibro-Acoustics more deeply. The book should be of interest to anyone interested in sound and vibration, vehicle acoustics, ship acoustics and inter...
10. Measurement system for wind turbine acoustic noise assessment based on IEC standard and Qin′s model
Sun Lei; Qin Shuren; Bo Lin; Xu Liping; Stephan Joeckel
2008-01-01
A novel measurement system specially used in noise emission assessment and verification of wind turbine generator systems is presented that complies with specifications given in IEC 61400-11 to ensure the process consistency and accuracy. Theory elements of the calculation formula used for the sound power level of wind turbine have been discussed for the first time, and detailed calculation procedure of tonality and audibility integrating narrowband analysis and psychoacoustics is described. With a microphone and two PXI cards inserted into a PC, this system is designed in Qin′s model using VMIDS development system. Benefiting from the virtual instrument architecture, it′s the first time that all assessment process have been integrated into an organic whole, which gives full advantages of its efficiency, price, and facility. Mass experiments show that its assessment results accord with the ones given by MEASNET member.
11. Acoustic biosensors
Fogel, Ronen; Seshia, Ashwin A.
2016-01-01
Resonant and acoustic wave devices have been researched for several decades for application in the gravimetric sensing of a variety of biological and chemical analytes. These devices operate by coupling the measurand (e.g. analyte adsorption) as a modulation in the physical properties of the acoustic wave (e.g. resonant frequency, acoustic velocity, dissipation) that can then be correlated with the amount of adsorbed analyte. These devices can also be miniaturized with advantages in terms of cost, size and scalability, as well as potential additional features including integration with microfluidics and electronics, scaled sensitivities associated with smaller dimensions and higher operational frequencies, the ability to multiplex detection across arrays of hundreds of devices embedded in a single chip, increased throughput and the ability to interrogate a wider range of modes including within the same device. Additionally, device fabrication is often compatible with semiconductor volume batch manufacturing techniques enabling cost scalability and a high degree of precision and reproducibility in the manufacturing process. Integration with microfluidics handling also enables suitable sample pre-processing/separation/purification/amplification steps that could improve selectivity and the overall signal-to-noise ratio. Three device types are reviewed here: (i) bulk acoustic wave sensors, (ii) surface acoustic wave sensors, and (iii) micro/nano-electromechanical system (MEMS/NEMS) sensors. PMID:27365040
12. 高速铁路声屏障声学计算模式研究%The Study of Acoustic Computing Model for the Noise Barrier of High-Speed Railway
苏卫青; 潘晓岩; 叶平
2013-01-01
基于多通道阵列式声源识别系统和多通道噪声振动实时采集分析系统,对京津城际和京沪高速铁路列车运行状态下的噪声源、空间声场分布以及声屏障降噪效果进行测试和分析.将高速列车声源等效为下部噪声和上部噪声两部分:下部噪声以轮轨噪声和车体气动噪声为主,其声源等效位置确定为轨面以上0.6m处；上部噪声以弓网噪声为主,其声源等效位置确定为轨面以上3.3m处.由此提出基于双声源作为等效声源和以1250 Hz作为等效频率的高速铁路声屏障声学计算模式,给出声屏障插入损失和加长量修正计算公式,所得到声屏障的声学计算结果与实测结果吻合.%Based on multi-channel aligned array sound source identification system and multi-channel noise vibration real-time acquisition analysis system, the noise source, the distribution of spatial sound field and the reduction effect of noise barrier were tested and analyzed under train operation state for Beijing-Tianjin intercity and Jing-Hu high-speed railway. The sound source of high-speed train is equivalent to lower part noise and upper part noise. The noise of lower part mainly includes wheel rail noise and the aerodynamic noise of car body, and its sound source is equivalent to 0. 6 m above rail surface. The noise of upper part is mainly pantograph-catenary noise, and its sound source is equivalent to 3. 3 m above rail surface. Therefore, the acoustic computing model for the noise barrier of high-speed railway is proposed, which is based on dual sound source as the equivalent sound source and 1 250 Hz as the equivalent frequency. The correction and calculation formula for the insertion loss and extension part of noise barrier is given. The obtained acoustic computing result of sound barrier agrees well with the measured result.
13. Noise sensitivity and sleep disturbance
Laszlo, H.E.; Janssen, S.A.; Babisch, W.; Hansell, A.L.
2012-01-01
It has been shown that noise induced health effects are strongly related to non-acoustical factors such as noise sensitivity. It is a stable personality trait and it can be conceptualised as a causal pathway confounder and/or effect modifier between noise and health. Furthermore noise sensitivity pa
14. Aero-acoustic Computations of Wind Turbines
Shen, Wen Zhong; Michelsen, Jess; Sørensen, Jens Nørkær
2002-01-01
A numerical algorithm for acoustic noise generation is extended to 3D flows. The approach involves two parts comprising a viscous incompressible flow part and an inviscid acoustic part. In order to simulate noise generated from a wind turbine, the incompressible and acoustic equations are written...
15. Acoustic Signal Feature Extraction of Vehicle Targets
蓝金辉; 马宝华; 李科杰
2002-01-01
Acoustic signal feature extraction is an important part of target recognition. The mechanisms for producing acoustic signals and their propagation are analyzed to extract the features of the radiated noise from different targets. Analysis of the acoustic spectra of typical vehicle targets acquired outdoors shows that the vehicles can be classified based on the acoustic spectra and amplitudes.
16. 增压发动机的进气噪声源提取和进气噪声的预测%Extraction of Intake Acoustic Source and Prediction of Intake Noise of a Turbocharged Engine
刘联鋆; 郝志勇; 钱欣怡; 胡先锋
2013-01-01
试验测量了安装不同声学负载时的增压发动机的进气噪声,分别用边界元法和计算流体动力学法(CFD法)计算了无流和有流条件下声学负载的声学特性,其中CFD法计算了负载的传递矩阵.用四负载最小二乘法提取进气噪声源,并计算了安装某负载时的进气噪声,与测量值对比,评估提取声源的准确性,发现结合CFD法计算的声源比边界元法计算值更准确,根据CFD法计算得到的进气噪声的2阶、4阶和6阶成分与测量值的最大误差为9dB.进一步结合用CFD法获得的噪声源和空滤器的传递矩阵,预测了安装空滤器时的进气噪声,预测结果不如安装负载时的预测结果准确,其2阶、4阶和6阶成分与测量值的最大误差为23 dB,但预测结果和测量结果的变化趋势一致,说明了采用CFD法计算传递矩阵,提取进气噪声源并预测进气噪声的可行性.%Measurement on intake noise of a turbocharged engine under various acoustic loads was made.Acoustic characteristics and loads were calculated using boundary element method (BEM) and computational fluid dynamics (CFD) approaches in the presence and absence of flow. Transfer matrices of the loads were calculated by CFD. A four-load least squares method was used to extract the intake acoustic source and the intake noise with certain load was calculated. Accuracy of the acoustic source was evaluated. Acoustic source extracted by CFD gains better accuracy than that by BEM. Maximum deviation of the intake noise of the calculated 2 nd, 4 th and 6 th order with CFD simulation is 9 dB to the measured results. Intake noise was predicted from the comparison of CFD calculated intake acoustic source and transfer matrix of air filter. Prediction without load is not accurate to that with load. Maximum deviation of intake noise of the calculated 2 nd, 4 th and 6 th order is 23 dB. But the trend of predicted intake noise is consistent to that of measured result
17. Analysis of Acoustic Environment Index of Aircraft Noise and Planning and Selection of the Location of Airport%机场飞机噪声声环境指标分析及规划选址分析
田瑞丽; 李洪波; 冯海波; 马丽霞
2014-01-01
The location of different sizes of airport is different, and the impact degree of the aircraft noise is different. Rational utilization of the land surrounding the airport can reduce the impact of aircraft noise. This article lists acoustic environmental indicators of aircraft noise of the different scale domestic airport, and analyzes the land use planning around the airport.%不同规模的机场，选址不同，飞机噪声影响程度不同，对机场周边土地进行合理利用，以降低飞机噪声影响，本文列出了国内不同规模机场飞机噪声的声环境指标，并对机场周围土地利用规划进行了分析。
18. Acoustic Sensitivity Analysis on Dominant Transmission Paths for Noise Reduction Design of Super-large Crude Carrier%超大型油轮降噪设计主传递路径族灵敏度方法
高处; 杨德庆
2014-01-01
针对振动噪声传递路径降噪设计是提高船舶声学性能的有效措施之一。目标舱室振动噪声传递路径并不唯一，其中多条主要路径传递了大部分振动与噪声能量。利用作者提出的基于声振熵概念及图论中K则最短路径理论的声振熵赋权图法，能够快速识别船舶舱室噪声主要传递路径族。在此基础上，计算噪声主传递路径族上声学设计参数变化对目标舱室声压影响的灵敏度，调整有关声学设计措施，此即降噪设计主传递路径族灵敏度方法。提出适用于大型船舶噪声主传递路径分析及主传递路径族灵敏度的降噪设计通用流程，通过超大型油轮降噪声学设计实例，说明了该方法的有效性。%One of the effective measures to improve the acoustic performance of ships is to perform a noise reduction design along the sound transmission path. However, there are usually several transmission paths to the target cabin, of which some dominant paths transmit a large amount of noise and vibration energy. Using the proposed vibro-acoustical entropy weighted graph method based on the vibro-acoustical entropy concept and K shortest path theory, the dominant transmission paths of the cabin noise can be identified quickly. On this basis, the sensitivity of influence of the change of the acoustic design parameters of the dominant transmission paths on the sound pressure of the target cabin is calculated. And the method for noise reduction design can be adjusted and determined efficiently. This is known as the sensitivity method of dominant transmission paths in noise reduction design. A general program of this method for noise reduction design of large ships is designed. A numerical example of a super large crude carrier is given and the results show the effectiveness of this method.
19. Handbook of Engineering Acoustics
Möser, Michael
2013-01-01
This book examines the physical background of engineering acoustics, focusing on empirically obtained engineering experience as well as on measurement techniques and engineering methods for prognostics. Its goal is not only to describe the state of art of engineering acoustics but also to give practical help to engineers in order to solve acoustic problems. It deals with the origin, the transmission and the methods of the abating different kinds of air-borne and structure-borne sounds caused by various mechanisms – from traffic to machinery and flow-induced sound. In addition the modern aspects of room and building acoustics, as well as psychoacoustics and active noise control, are covered.
20. Proceedings of the Alberta Acoustical Society's 2007 spring conference on environmental and occupational noise : leave no tone unturned. Version 2
NONE
2007-07-01
This conference provided a forum for the discussion of innovations in noise control and noise management technologies. The focus of the conference was to share practical experiences in environmental and occupational noise identification, measurement, regulation, and control. It presented research and case studies to highlight current issues and advancements in technology and software. Strategies for reducing workplace noise exposure were identified along with strategies for responsible management of human noise exposure. In addition to a plenary session, the conference included sessions on low frequency noise; modelling and measurement; noise control; occupational noise; issues related to environmental noise; wildlife and noise impacts; and, environmental regulations. The conference featured 47 presentations, of which 14 have been catalogued separately for inclusion in this database. refs., tabs., figs.
1. Wind turbine acoustics
Hubbard, Harvey H.; Shepherd, Kevin P.
1990-12-01
Available information on the physical characteristics of the noise generated by wind turbines is summarized, with example sound pressure time histories, narrow- and broadband frequency spectra, and noise radiation patterns. Reviewed are noise measurement standards, analysis technology, and a method of characterizing wind turbine noise. Prediction methods are given for both low-frequency rotational harmonics and broadband noise components. Also included are atmospheric propagation data showing the effects of distance and refraction by wind shear. Human perception thresholds, based on laboratory and field tests, are given. Building vibration analysis methods are summarized. The bibliography of this report lists technical publications on all aspects of wind turbine acoustics.
2. Application of Microporous Fiber Composite Acoustic Board in the Noise Control Engineering of Urban Substations%微孔纤维复合吸声板在城市变电站降噪中的应用
田一; 陈建胜; 刘主光; 卢卫疆; 陈新; 韩钰
2016-01-01
Due to the mismatch of noise reduction performance and the frequency feature of substation noise, the poor weather resistance and durability, most substation noise reduction material cannot limit the noise emission for a long time. Microporous fiber composite acoustic board, developed by the State Grid Corporation, conquers the shortcomings of traditional material. It consists of Aluminum fiber board and micro-perforated panel, with the sound absorption feature of large low-frequency absorption coefficient, good absorbing ability for wide frequency, environmental friendly performance and good weather resistance and durability. Microporous fiber composite acoustic board has been made into sound-absorbing wall, muffler, sound barrier and sound insulation cover and applied to the noise control engineering of substations, which makes the noise level of station boundary reach the GB12348—2008 Emission Standard for Industrial Enterprise Noise at Boundary. It has great potential in the area of noise control for urban substations.%现有的大多数变电站降噪材料，因降噪特性与变电站噪声频谱特征不匹配，以及耐候、耐久性不达标，很难长久限制噪声排放水平。由国网公司研发的新型吸声材料——微孔纤维复合吸声板克服了以上缺陷，该吸声板由铝纤维板和微穿孔板复合而成，具备“低频高效、宽频有效”的吸声特性，而且绿色环保、耐候耐久。微孔纤维复合吸声板加工而成的吸声壁面、消声器、声屏障和隔声罩已在多座变电站降噪工程中投入使用，将站界噪声控制在GB 12348—2008《工业企业厂界环境噪声排放标准》的限值要求之下，在城区变电站降噪领域中显示出广阔的应用前景。
3. 高速列车气动噪声Lighthill声类比的有限元分析%Finite Elements Analysis of High - speed Train Wind Noise in Lighthill' s Acoustic Analogy
杨晓宇; 高阳; 程亚军; 刘凤华
2011-01-01
With the constant increase of the trains' speed, the aerodynamic noise gradually succeeds the traditional track noise and becomes the main noise source of the high-speed trains. In this paper, a hybrid CFD/CAA wind noise model for the high speed trains based on Lighthill' s analogy is constructed utilizing a professional finite elements acoustic simulator ACTRAN-Aeroacoustics. Numerical results of fluid and acoustic fields are reported and discussed. Some important issues for further development of the simulation model are discussed. The simulation results show that there are three dominant locations for the aerodynamic noise sources which depend on the shape of the train. With the use of this model, the influence of the train's shape on the wind noise can be analyzed, and the optimization for low noise design of the train can be realized.%随列车行驶速度逐年提高,气动噪声源逐渐超越轮轨噪声成为高速列车最主要噪声源.通过ACTRAN -Aeroacoustics建立基于Lighthill声类比理论的高速列车气动噪声CFD/CAA混合数值分析模型.计算并讨论非定常流场与气动声场计算结果,并分析此数值模型可以进一步完善的一些重要方面.目前数值模拟结果表明列车高速行驶状态气动噪声源主要集中在与车身气动外形密切相关的三类位置上,且通过当前模型可以有效剖析列车车身气动外形设计对气动噪声的影响以及相应的高速列车低噪音优化途径.
4. Ocean acoustic reverberation tomography.
Dunn, Robert A
2015-12-01
Seismic wide-angle imaging using ship-towed acoustic sources and networks of ocean bottom seismographs is a common technique for exploring earth structure beneath the oceans. In these studies, the recorded data are dominated by acoustic waves propagating as reverberations in the water column. For surveys with a small receiver spacing (e.g., ocean acoustic reverberation tomography, is developed that uses the travel times of direct and reflected waves to image ocean acoustic structure. Reverberation tomography offers an alternative approach for determining the structure of the oceans and advancing the understanding of ocean heat content and mixing processes. The technique has the potential for revealing small-scale ocean thermal structure over the entire vertical height of the water column and along long survey profiles or across three-dimensional volumes of the ocean. For realistic experimental geometries and data noise levels, the method can produce images of ocean sound speed on a smaller scale than traditional acoustic tomography.
5. Acoustic Ground-Impedance Meter
Zuckerwar, A. J.
1983-01-01
Helmoltz resonator used in compact, portable meter measures acoustic impedance of ground or other surfaces. Earth's surface is subject of increasing acoustical investigations because of its importance in aircraft noise prediction and measurment. Meter offers several advantages. Is compact and portable and set up at any test site, irrespective of landscape features, weather or other environmental condition.
6. Noise annoys: effects of noise on breeding great tits depend on personality but not on noise characteristics
Naguib, M.; Oers, van K.; Braakhuis, A.; Griffioen, M.; Goede, de P.; Waas, J.R.
2013-01-01
Anthropogenic noise can have serious implications for animals, especially when they communicate acoustically. Yet, the impacts of noise may depend not only on noise characteristics but also on an individual's coping style or personality. We tested whether noise is more disturbing if it masks communi
7. CALCULATION OF ACOUSTIC EFFICIENCY OF PORTABLE ACOUSTIC SCREEN
Aleksandr Skvortsov
2016-03-01
Full Text Available The research of influence of life environment adverse factors on physical development and health of population is an actual problem of ecology. The aspects of the most actual problems of the modern world, namely environmental industrial noise pollution are considered in the article. Industrial facilities everywhere have noisy equipment. Noise is a significant factors of negative influenceon people and environment. Combined effects of noise and of other physical pollutions on people may cause amplification of their negative impact. If the noise pollution level from the object in a residential area exceeds the permissible levels (MPL, noise protection measures can be initiated. Today, the most common design decisions for noise protection are sound absorbing construction, noise screens and barriers, acousting housings, soundproff cabins. Many of them are popular, others are less known. The article deals with one of the most wide spread means of noise protection – a portable acoustic screen. The aim of the research is to determine the efficiency of portable acoustic screens. It is shown that the installation of such structures can reduce the average value of the sound level. The authors analyzed acoustic screens as device to reduce noise pollution. The authors offer a potable acoustic screen differing from the used easyness, mobility, minimum price and good sound protective properties. Effectiveness, a sound absorption coefficient and sound conductivity coefficient of a portable acoustic screen are evaluated. The descriptions of the algorithm calculations and the combination of technical solutions have practical originality. The results of the research demonstrate the advantages of the proposed solutions for reducing noise levels in the agro-industrial complex.
8. Active Noise Control for Dishwasher noise
Lee, Nokhaeng; Park, Youngjin
2016-09-01
The dishwasher is a useful home appliance and continually used for automatically washing dishes. It's commonly placed in the kitchen with built-in style for practicality and better use of space. In this environment, people are easily exposed to dishwasher noise, so it is an important issue for the consumers, especially for the people living in open and narrow space. Recently, the sound power levels of the noise are about 40 - 50 dBA. It could be achieved by removal of noise sources and passive means of insulating acoustical path. For more reduction, such a quiet mode with the lower speed of cycle has been introduced, but this deteriorates the washing capacity. Under this background, we propose active noise control for dishwasher noise. It is observed that the noise is propagating mainly from the lower part of the front side. Control speakers are placed in the part for the collocation. Observation part of estimating sound field distribution and control part of generating the anti-noise are designed for active noise control. Simulation result shows proposed active noise control scheme could have a potential application for dishwasher noise reduction.
9. Noise Source Location Optimization
Ed O’Keefe
1994-01-01
Full Text Available This article describes a method to determine locations of noise sources that minimize modal coupling in complex acoustic volumes. Using the acoustic source scattering capabilities of the boundary element method, predictions are made of mode shape and pressure levels due to various source locations. Combining knowledge of the pressure field with a multivariable function minimization technique, the source location generating minimum pressure levels can be determined. The analysis also allows for an objective comparison of “best/worst” locations. The technique was implemented on a personal computer for the U.S. Space Station, predicting 5–10 dB noise reduction using optimum source locations.
10. Effects of acoustic treatment on the interior noise levels of a twin-engine propeller aircraft - Experimental flight results and theoretical predictions
Beyer, T. B.; Powell, C. A.; Daniels, E. F.; Pope, L. D.
1984-01-01
In-flight noise level measurements were made within two cabin configurations of a general aviation business aircraft. The Fairchild Merlin IVC twin-engine aircraft was tested with bare walls and fiberglass insulation and in an executive trim configuration. Narrow-band and octave format data were subjected to analyses which permitted identification of the blade passage harmonics (BPH). Cabin noise level reductions (insertion losses) due to added insulation varied with position in the cabin, the BPH number, cabin pressure, and engine torque. The measurements were closely predicted using the propeller aircraft interior noise (PAIN) mode.
11. Noise suppression by noise
Vilar, J. M. G.; Rubí Capaceti, José Miguel
2001-01-01
We have analyzed the interplay between an externally added noise and the intrinsic noise of systems that relax fast towards a stationary state, and found that increasing the intensity of the external noise can reduce the total noise of the system. We have established a general criterion for the appearance of this phenomenon and discussed two examples in detail.
12. Acoustic design by topology optimization
Dühring, Maria Bayard; Jensen, Jakob Søndergaard; Sigmund, Ole
2008-01-01
To bring down noise levels in human surroundings is an important issue and a method to reduce noise by means of topology optimization is presented here. The acoustic field is modeled by Helmholtz equation and the topology optimization method is based on continuous material interpolation functions...
13. 多级轴流压气机内部声共振的噪声特征研究%Investigation into noise characteristics corresponding to acoustic resonance in a multi-stage axial compressor
栾孝驰; 沙云东; 赵奉同; 崔现智
2014-01-01
基于某型多级轴流压气机部件试验，主要研究高压一级转子叶片出现高振幅级叶片振动时，压气机流道内部的噪声特性，重点分析换算流量(ma)的变化和静子导流叶片连动角度(S0)的变化对压气机内部噪声信号的影响。分析结果表明，此现象可能与压气机环形空间中的声共振有关，压气机中发生的所有共振都在一个频率下，即声共振频率呈现锁频现象；此外，谐振最大时，声共振频率处的声能量超过了通常较大的叶片通过频率处的声能量，在整个声压级谱中占主导地位；ma 和S0的变化对声共振频率不产生影响，但ma 和S0的变化对压气机内部噪声信号特征和转子叶片振动应力幅值影响较大。研究结果对进一步研究声共振现象有一定的参考价值。%Based on a certain type of a multi-stage axial compressor rig testing,the characteristics of noise in the compressor passage compressor is investigated under the condition that blade vibrations of high amplitude levels occurred to the first rotor blades of high pressure. And the analysis focuses on the effect of the changes of the corrected mass flow( ma ) and the linkage angle of stator guide vane ( S0 ) on the noise signal in the compressor. The results show thatthis phenomenon is associated with acoustic resonance of the compressor annulus space,and the resonance occurring all over the compressor is under one single frequency,which means that the acoustic frequency locking takes place. In addition,the sound energy of the acoustic resonance frequency exceeds that of the usually dominated blade passing that frequency when the amplitude of blade vibrations reaches the maximum,which dominates in the whole sound pressure level spectrum. The acoustic resonance frequency is unaffected by and,but the changes of ma and S0 have significant influence on internal noise signal characteristics in the compressor and the vibration stress
14. Active noise control primer
Snyder, Scott D
2000-01-01
Active noise control - the reduction of noise by generating an acoustic signal that actively interferes with the noise - has become an active area of basic research and engineering applications. The aim of this book is to present all of the basic knowledge one needs for assessing how useful active noise control will be for a given problem and then to provide some guidance for designing, setting up, and tuning an active noise-control system. Written for students who have no prior knowledge of acoustics, signal processing, or noise control but who do have a reasonable grasp of basic physics and mathematics, the book is short and descriptive. It leaves for more advanced texts or research monographs all mathematical details and proofs concerning vibrations, signal processing and the like. The book can thus be used in independent study, in a classroom with laboratories, or in conjunction with a kit for experiment or demonstration. Topics covered include: basic acoustics; human perception and sound; sound intensity...
15. 噪音环境下桥梁损伤声发射定位技术研究%Research on the location technology of bridge damage based on acoustic emission under ambient noise
刘茂军; 葛若东; 王根伟
2015-01-01
为研究噪音环境下桥梁损伤的声发射定位方法，并获取相应的技术参数，在一座运营中的预应力钢筋混凝土桥梁的箱梁内部进行了声发射定位试验，通过定位参数的选取、断铅模拟损伤的声发射定位试验、声发射信号的滤波除噪、定位图聚类等一系列试验，达到了比较满意的定位效果，定位误差控制在50 mm以内，并获得了桥梁检测中的声发射门槛值、定位波速以及三个定位时间参数值[峰值定义时间( PDT)、撞击定义时间( HDT)、撞击锁闭时间( HLT)]。试验结果表明，在运营桥梁上进行声发射损伤定位时，门槛值设为40 dB可以滤除大部分环境噪音，同时通过关联图对比分析、利用数字滤波除噪，并对定位图进行聚类，可以进一步提高定位精度，最终误差可以控制在50 mm以内。研究结果可为声发射损伤定位技术在桥梁检测及监测方面的推广应用提供借鉴。%In order to develop abridge damage location method under ambient noise and to obtain corresponding acoustic emission parameters, an acoustic emission location test was performed in the box girder of an in-service pre-stressed concrete bridge. By selecting location parameters, by per-forming acoustic emission location test and breaking leads to simulate damage, by filtering acoustic emission signal and locating graph clustering, a relatively satisfying location effect is obtained with the location error controlled in less than 50 mm. The acoustic emission detection threshold, the wave velocity, as well as the three location time values including the peak definition time (PDT), hit def-inition time ( HDT) and hit locking time ( HLT) were obtained. The test shows that, during the lo-cation of damage by acoustic emission on an in-service bridge, most of the ambient noise can be fil-tered out by setting the threshold value to 40 dB, and through the correlation diagram analysis, the use of
16. Study on Diesel Engine's Oil Pan's Modal of Acoustic-Liquid-Vibration Coupling System of Noise%柴油机油底壳声液振耦合系统噪声模态研究
胡启国; 李力克; 陈万德
2013-01-01
Noise analysis for the diesel engine oil pan casing vibration analysis only and ignore the lubricating fluid and cavity effects. The use of acoustic-liquid-vibration coupling finite element theory, coupling system element model is established of oil pan, oil and internal cavity of oil pan, and the modal of the finite element is analysised, then the vibration frequency of the oil pan is measured and analysised. Research oil pan system in the acoustic fluid coupled vibration mode was significantly lower vibration and noise enhancement, especially in the strong coupling 118.26 Hz modal frequencies. Lubricating fluid in the oil pan when the low-frequency sound vibration coupled system is less liquid, at high frequencies is more significant impact on the system.%针对柴油机油底壳噪声分析中只分析壳体振动而忽略了润滑液和空腔影响,利用声液振耦合有限元理论,建立油底壳结构有限元模型,润滑油、内部空腔声学有限元模型,油底壳声液振耦合系统有限元模型,并对各有限元模型进行模态研究,然后对实际油底壳振动频谱特性进行验证分析.通过研究得到油底壳在声液振耦合系统模态下振动和噪声值明显增强,特别是在118.26 Hz强耦合模态频率下.油底壳中润滑液在低频时对声液振耦合系统影响较小,在高频时对系统影响较为明显.
17. Psycho-acoustical valuation of pleasant and less perceptible sound characters in wind turbine noise; Psyko-akustisk vaerdering av behagliga och mindre maerkbara ljudkaraktaerer i vindkraftverksljud - interaktiv utvaerdering och akustisk beskrivning av den skvalpande karaktaeren
2001-03-01
The report describes phase 3 in the ongoing project 'Perception and annoyance of wind turbine sounds'. The overall aim of the project is to increase the knowledge of annoyance and perception of wind turbine sounds in order for the industry to optimise wind turbine constructions. The specific aim for phase 3 was to evaluate the most noticeable and annoying psycho-acoustical character described as 'lapping'. The lapping characteristic was evaluated in experimental studies comprising in total 24 test subjects. With the object to obtain a pleasant sound test subjects were asked to vary four parameters related to the psycho-acoustical perception of 'lapping' in the original sound. The variations of parameters were carried out using an interactive sound processing system and done in such a way so the resulting sound always had a constant dBA level. The resulting values of three of the four parameters were significantly different compared to the original sound. A pleasant sound thus had low contents of the different lapping characteristics. While no difference was found between the original sound and the resulting sound with regard to the equivalent frequency spectra, some differences could be detected using Zwickers loudness calculations. Some differences may be attributed to a lower degree of roughness in the 'pleasant sound'. It is however more likely that the difference between the noises as regard the content of specific loudness in the frequency range of 1270 to 3150 may be of greater importance. Analysis of conventional acoustical measures were not sufficient to predict subjects perception of noticeable and unpleasant characteristics in wind turbine sounds. Further analysis should be pursued of how to best describe an unpleasant or pleasant wind turbine sound.
18. Acoustical characterization of portuguese libraries
António Pedro Oliveira de Carvalho; António Eduardo Batista da Costa
2010-01-01
This paper presents the acoustical characterization of the main reading room of 28 public li-braries in Portugal. In situ measurements were held regarding the interior sound pressure lev-els (background noise, with and without the HVAC equipment working), the Noise Criteria and Noise Rating values (NC/NR), the objective speech intelligibility using the Rapid Speech Transmission Index (RASTI) and Reverberation Time (125 to 4k Hz). Two groups of librar-ies were formed (Classic and Modern librar...
19. Classroom acoustics: Three pilot studies
Smaldino, Joseph J.
2005-04-01
This paper summarizes three related pilot projects designed to focus on the possible effects of classroom acoustics on fine auditory discrimination as it relates to language acquisition, especially English as a second language. The first study investigated the influence of improving the signal-to-noise ratio on the differentiation of English phonemes. The results showed better differentiation with better signal-to-noise ratio. The second studied speech perception in noise by young adults for whom English was a second language. The outcome indicated that the second language learners required a better signal-to-noise ratio to perform equally to the native language participants. The last study surveyed the acoustic conditions of preschool and day care classrooms, wherein first and second language learning occurs. The survey suggested an unfavorable acoustic environment for language learning.
20. Proceedings of the 1987 national conference on noise control engineering: High technology for noise control
Tichy, J.; Hayek, S.
1987-01-01
This book consists of nine sections, each containing several papers. The section titles are: Emission: Noise Sources; Physical Phenomena; Noise Control Elements; Vibration: Generation, Transmission, Isolation and Reduction; Immission: Physical Aspects of Environmental Noise; Immission: Effects of Noise; Analysis; Requirements; and Biomedical Uses of Acoustics.
1. Product Sound: Acoustically pleasant motor drives
Mathe, Laszlo
The work in this thesis is focused on the acoustic noise generated by electrical motors driven by a pulse width modulated (PWM) power electronic inverter. In a usual inverter based electrical drive, the modulation uses fixed switching frequency; that introduces a set of harmonics in the acoustic...... spectra transforming the acoustic noise generated by the motor in a strong whistling noise. To maintain high efficiency for the entire drive, the switching frequency is typically kept around 4 kHz. However, this is the range where the human ear is the most sensitive. The main goal of this thesis...... is to ameliorate this whistling acoustic noise, while maintaining the efficiency of the drive. The first chapter of the report is an introductory chapter where the motivation, objectives, limitations and an overview on electrical motor acoustics are presented. A list of main contributions of this PhD project...
2. Acoustic Liner for Turbomachinery Applications
Huff, Dennis L.; Sutliff, Daniel L.; Jones, Michael G.; Hebsur, Mohan G.
2010-01-01
The purpose of this innovation is to reduce aircraft noise in the communities surrounding airports by significantly attenuating the noise generated by the turbomachinery, and enhancing safety by providing a containment barrier for a blade failure. Acoustic liners are used in today's turbofan engines to reduce noise. The amount of noise reduction from an acoustic liner is a function of the treatment area, the liner design, and the material properties, and limited by the constraints of the nacelle or casement design. It is desirable to increase the effective area of the acoustic treatment to increase noise suppression. Modern turbofan engines use wide-chord rotor blades, which means there is considerable treatment area available over the rotor tip. Turbofan engines require containment over the rotors for protection from blade failure. Traditional methods use a material wrap such as Kevlar integrated with rub strips and sometimes metal layers (sandwiches). It is possible to substitute the soft rub-strip material with an open-cell metallic foam that provides noise-reduction benefits and a sacrificial material in the first layer of the containment system. An open-cell foam was evaluated that behaves like a bulk acoustic liner, serves as a tip rub strip, and can be integrated with a rotor containment system. Foams can be integrated with the fan-containment system to provide sufficient safety margins and increased noise attenuation. The major innovation is the integration of the foam with the containment.
3. Acoustic and economic analysis of the use of palm tree pruning waste in noise barriers to mitigate the environmental impact of motorways.
Gil-Lopez, Tomas; Medina-Molina, Manuel; Verdu-Vazquez, Amparo; Martel-Rodriguez, Basilio
2017-04-15
This research has a twofold environmental benefit. On the one hand, there is the recycling of a waste by-product and, on the other hand, the reduction of traffic noise pollution levels. The objective of this study is to determine and evaluate the use of a mixture of shredded palm tree pruning waste with dampened topsoil in the construction of noise barriers. With a view to efficiently recycling pruning waste and using an environmentally-friendly material which does not pose any environmental risks at the end of its useful life, the composition offering the best sound absorption has been analyzed. Based on the results obtained, a completely eco-friendly roadside noise barrier (RNB) 1:1 scale model was built, and noise levels measured at various points close to it. Significant sound absorption benefits were detected, not only in the shaded area behind the barrier, but also in the unprotected area immediately above the barrier. Furthermore, the economic feasibility of both the construction and recycling processes has been calculated.
4. A new de-noising method for acoustic emission signal of rolling bearings with low speed based on morphological filtering in frequency domain%基于频域形态滤波的低速滚动轴承声发射信号降噪新方法
李修文; 阳建宏; 黎敏; 徐金梧
2013-01-01
声发射检测技术以其灵敏度高、频响范围宽、信息量大等优点,为机械故障诊断提供了一条新的检测途径,但应用于旋转机械设备时,容易混入各种有色噪声.当噪声频率与声发射信号重叠时,传统的降噪方法难以满足要求.将形态滤波应用到信号频域,可以有效消除有色噪声的干扰.根据声发射频响特性,对频谱进行拟合平滑高斯白噪声的影响,最后重构到时域.仿真和实际低速轴承信号表明此方法具有较好的降噪效果,有利于信号后续的处理和分析.%Acoustic emission technique provides a new measuring approach for machinery fault diagnosis because of its characteristics of high sensitivity, wide frequency response range and containing much information. An acoustic emission signal often is mixed with a variety of color noise when applied to a rotating machinery. Traditional noise reduction methods can not meet the measuring requirements when the frequencies of noise and those of acoustic emission signals overlap. Here, morphological filtering was applied to eliminate color noise in frequency domain. According to the acoustic emission frequency response characteristic, a spectrum was fitted in order to smooth white Gaussian noise. Finally, a time domain waveform was reconstructed. The simulation results and the real signals of rolling bearings with low speed showed that the proposed methodology can achieve good effect of noise reduction, and is beneficial to the subsequent processing and analysis of signals.
5. Flow noise in sonar applications
Henke, Christian
2016-01-01
In this paper we present an investigation of flow noise in sonar applications. Based on a careful identification of the dominant coupling effects, the acoustic noise at the sensor position resulting from the turbulent wall pressure fluctuations is modelled with a system of hydrodynamic, bending and acoustic waves. We describe an analytical solution of the problem which is based on a coupled eigenfunction expansion method. Finally, it is demonstrated that the analytical solution describes the flow noise generation and propagation mechanisms of the considered sea trials.
6. Measuring Acoustic Wave Transit Time in Furnace Based on Active Acoustic Source Signal
Zhen Luo; Feng Tian; Xiao-Ping Sun
2007-01-01
Accurate measurement of transit time for acoustic wave between two sensors installed on two sides of a furnace is a key to implementing the temperature field measurement technique based on acoustical method. A new method for measuring transit time of acoustic wave based on active acoustic source signal is proposed in this paper, which includes the followings: the time when the acoustic source signal arrives at the two sensors is measured first; then, the difference of two arriving time arguments is computed, thereby we get the transit time of the acoustic wave between two sensors installed on the two sides of the furnace. Avoiding the restriction on acoustic source signal and background noise, the new method can get the transit time of acoustic wave with higher precision and stronger ability of resisting noise interference.
7. 箱型桥梁结构的面板声学贡献分析%Application of panel acoustic contribution theory in study of noise fro m simply -supprted box girder in high speed rail way
刘林芽; 付奇川; 邵文杰; 李纪阳
2015-01-01
Taking the high speed railway 32 m concrete simply -supported box bridge as the research object,the theses used finite element software to set up for high speed railway track -bridge analysis model.Then,based on the theory of vehicle -track -bridge coupling vibration,this paper analyzed the vertical vibration of the struc-ture of the bridge.A vertical vibration response was finally gotten as boundary conditions,which we use in the boundary element model of box girder structure noise prediction.At the same time,based on panel acoustic con-tribution analysis theory,the box beam body panel pressure contribution analysis and panel acoustic power analy-sis were done.In this way,we determined the largest position of body radiation noise for box beam .The results of the study show that if the train speeds up to 200 km /h on the elevated rail,box beam body radiation noise mainly occur within the range of 0 -100 Hz,of which 20 Hz and 42 Hz are prominent peak.Meanwhile,by the panel acoustic contribution analysis,we come to the conclusion that the part of main radiation noise comes from the box girder roof and the two flank flange panel.%以高速铁路32 m 混凝土简支箱型桥梁为研究对象，通过有限元软件建立了轨道－桥梁分析模型，采用车辆－轨道－桥梁耦合振动理论，分析了桥梁结构的竖向振动，并将得到的竖向振动响应作为边界条件，导入到箱梁边界元模型中预测箱梁结构噪声。同时基于面板声学贡献分析理论，进行了箱梁梁体的面板声压贡献分析和声功率贡献分析，确定箱梁梁体辐射噪声的最大部位。研究结果表明：列车以200 km／h 的速度运行在高架轨道上时，箱梁梁体辐射噪声主要集中0－100 Hz 范围内，其中在20 Hz 和42 Hz 左右有比较突出峰值。同时由面板声学贡献分析可知箱梁梁体主要辐射噪声的部位是箱梁的顶板和两侧翼缘板下面板。
8. Noise and Tinnitus
1999-03-01
Full Text Available Tinnitus from the Latin word tinnire meaning ringing is the perception of sound within the human ear in the absence of corresponding external sound. The most common cause is noise induced hearing loss. Tinnitus may be induced by an acoustic trauma or a permanent noise in the workplace. In case that Tinnitus is induced by acoustic trauma the site of lesion is commonly the base of the cochlea. Tinnitus in the senile population is mostly accompanying presbycusis. Although the incidence of permanent tinnitus following noise exposure is high, little is published about this issue. In the current article we are aimed at studying the prevalence of tinnitus in Minoo and other manufactures.
9. 潜艇涡量场和流噪声等效声中心的数值预报%Numerical simulation of vorticity field and determination of equivalent acoustic source of flow noises for submarine
杨琼方; 王永生; 张明敏
2012-01-01
为了实现潜艇湍流噪声及其等效声中心的数值预报,在分析SUBOFF潜艇拖曳和自航状态下涡量场的基础上,采用大涡模拟与声学边界元相结合的方法,在频域内预报了流噪声空间分布、测点谱源级曲线和声指向性,求取了等效声中心位置并分析了其受螺旋桨旋转作用的影响.计算结果表明：附体与艇体结合部马蹄涡和附体端面诱导项链形涡对是潜艇涡量场的主要特征,且马蹄涡系具有较高的强度和稳定性;附体尾涡脱落频率存在19.22Hz的线谱,且在尾涡测点谱曲线中得到明确体现;随着频率增加,流噪声蝶形指向性对应的辐射瓣状区间数随波数增加,且正横方向声压要强于首尾方向;流噪声等效声中心位于距艇艏0.46倍艇长处,在10Hz～1kHz内总声源级为95.09dB;艇艉桨对附体马蹄涡系影响较小,但促使等效声中心迅速移至艇艉.%After the vorticity field of SUBOFF bare hull and appended submarine with 7-bladed highly skewed propeller under self-propulsion condition was analyzed, the spatial sound pressure distribution of flow noise and the observerrs source spectrum level curve as well as sound directivity were predicted in frequency domain by coupling large eddy simulation simulation and bindary element numerical a- coustics. Then the equivalent acoustic source of flow noise was determined and the effects of propeller operation on it were analyzed. Results show that horse-shoe vortex around appendages＇ junction and counter-rotating necklace vortex pair induced by flow over appendages＇ tip surface dominate the vortex field, and the horse-shoe vortex system are strong and stable. The appendages trailing edge vortex sheds with a line spectrum of 19.22 Hz, which exists in spectrum curve of monitors in wake also. As frequency increases, the number of acoustic lobes of butterfly directivity increases, and the sound pressure is stronger in beam aspect than that of bow and
10. Communication Acoustics
Blauert, Jens
Communication Acoustics deals with the fundamentals of those areas of acoustics which are related to modern communication technologies. Due to the advent of digital signal processing and recording in acoustics, these areas have enjoyed an enormous upswing during the last 4 decades. The book...... the book a source of valuable information for those who want to improve or refresh their knowledge in the field of communication acoustics - and to work their way deeper into it. Due to its interdisciplinary character Communication Acoustics is bound to attract readers from many different areas, such as......: acoustics, cognitive science, speech science, and communication technology....
11. Reduction of the acoustic noise emission of wind turbines by modification of rotor bade tip shapes, trailing edges and pitch angles. Final report; Geraeuschminderung durch Modifikation der Blattspitze, der Blatthinterkante und des Anstellwinkels von Windkraftanlagen. Abschlussbericht
Betke, K. [Oldenburg Univ. (Germany). Inst. fuer Technische und Angewandte Physik; Gabriel, J.; Klug, H. [Deutsches Windenergie-Institut gGmbH (DEWI), Wilhelmshaven (Germany); Schumacher, K.; Wittwer, G. [Abeking und Rasmussen Faserverbundtechnik GmbH, Lemwerder (Germany); Litzka [Foerdergesellschaft Windenergie e.V., Brunsbuettel (Germany); Seel [Seewind Windenergiesysteme GmbH, Walzbachtal (Germany); Petersen; Partmann [Tacke Windtechnik GmbH und Co. KG, Rheine (Germany); Kolbert [Ventis Energietechnik GmbH, Braunschweig (Germany)
1997-12-31
In cooperation with manufacturers of wind turbines and rotor blades acoustic measurements on modified tip shapes, trailing edges and pitch angles were performed in a wind tunnel and on real turbines. The results provide manufacturers, developers and operators of wind turbines with a tool to reduce the noise radiation from wind turbines. Significant noise reductions were obtained by tip shape modifications. The sound power level of a modified 600 kW wind turbine was less than 98 dB(A). Modifications of the trailing edge were less effective than expected from theory. Sharp trailing edges were almost as effective as serrated trailing edges but both require special procedures in production and handling. Pitch angle modifications led to significant noise reductions when the angle of attack was reduced. The power curve of the modified turbine was measured and resulted in an energy loss in the range of 1% while the noise was reduced by 2 dB(A). (orig.) [Deutsch] In Zusammenarbeit mit Herstellern von Windenergieanlagen und Rotorblaettern wurden akustisch wirksame Modifikationen der Blattspitze, der Blatthinterkante und des Blatteinstellwinkels im Windkanal vermessen. Die gewonnenen Erkenntnisse wurden bei unterschiedlichen realen Windenergieanlagen umgesetzt und die erzielte Geraeuschminderung durch direkte Vergleichsmessungen vor Ort bestimmt. Aus den Ergebnissen des Projektes lassen sich allgemeine Aussagen ueber Geraeuschminderungsmassnahmen an Windenergieanlagen ableiten. Es hat sich gezeigt, dass bei vielen Windenergieanlagen deutliche Reduzierungen der Geraeuschabstrahlung durch eine Veraenderung der Blattspitzenform erzielt werden koennen (erzwungener Umschlag) vermieden werden kann. Die Modifikation der Blattspitze fuehrte zu dem niedrigsten Schalleistungspegel in der 600 kW - Leistungsklasse von unter 98 dB(A). Bei den Modifikationen der Hinterkante konnte der erhoffte Erfolg bei saegezahnfoermigen Hinterkanten im Windkanal nicht nachgewiesen werden. Im
12. 航天电子设备多余物检测信号特性的影响因素分析%Factors affecting characteristics of acoustic signals in particle impact noise detection for aerospace devices
陈金豹; 翟国富; 王淑娟; 刘泳; 王洪元
2013-01-01
According to the mechanism of sound generation and the method of spectral analysis, the influences of the operation variables and particle physical parameters on acoustic spectrum are investigated systematically in the particle impact noise detection (PIND) for aerospace devices. The particle size, physical property, acceleration and frequency of vibration conditions are considered as four factors affecting acoustic signals, and the effect laws of them are presented. The physical property is determined as the key factor, and the feasibility of particle size and material identification is confirmed using the orthogonal test method. The results are of great value for identification of particles.%依据微粒碰撞产生声波的机理,运用频谱分析法,系统地研究航天电子设备多余物噪声检测过程中各操作变量和微粒物理参数对声波频谱的影响.通过单因素试验,详细分析了微粒粒径、微粒材质属性、振动力学条件中加速度和频率等4个因素对声音信号频谱分布的影响规律.同时,采用正交试验法确定了关键影响因素为微粒材质属性,并提出了微粒材质和粒径识别的可行性.该结果为进一步识别多余物微粒的参数提供了指导依据.
13. 4th Pacific Rim Underwater Acoustics Conference
Xu, Wen; Cheng, Qianliu; Zhao, Hangfang
2016-01-01
These proceedings are a collection of 16 selected scientific papers and reviews by distinguished international experts that were presented at the 4th Pacific Rim Underwater Acoustics Conference (PRUAC), held in Hangzhou, China in October 2013. The topics discussed at the conference include internal wave observation and prediction; environmental uncertainty and coupling to sound propagation; environmental noise and ocean dynamics; dynamic modeling in acoustic fields; acoustic tomography and ocean parameter estimation; time reversal and matched field processing; underwater acoustic localization and communication as well as measurement instrumentations and platforms. These proceedings provide insights into the latest developments in underwater acoustics, promoting the exchange of ideas for the benefit of future research.
14. Acoustical Evaluation of Combat Arms Firing Range, Grand Forks AFB, North Dakota
2015-01-23
noise for the M870 and M9 in accordance with Air Force Occupational Safety and Health (AFOSH) Standard 48-20 due to acoustical reflections. Conversely...15. SUBJECT TERMS Impulse noise , impact noise , continuous noise , decay time, Combat Arms, CATM, firing range, hearing, acoustics , noise , firearms...Combat Arms instructors wearing dual hearing protection. Note: Moldex Camo ear plugs have a noise reduction rating of 33 decibels A-Weighted (dBA
15. Acoustic telemetry
National Oceanic and Atmospheric Administration, Department of Commerce — To determine movements of green turtles in the nearshore foraging areas, we deployed acoustic tags and determined their movements through active and passive acoustic...
16. Acoustic Monitoring for Spaceflight Vehicle Applications Project
National Aeronautics and Space Administration — This SBIR will develop and demonstrate acoustic sensor technology enabling real-time, remotely performed measuring and monitoring of sound pressure levels and noise...
17. Aero-Acoustic Propulsion Lab (AAPL)
Federal Laboratory Consortium — This facility is an acoustically treated geodesic dome. The 130-ft-diameter dome is 65-ft high and acts as a noise barrier, protecting adjacent Glenn buildings and...
18. Underwater Noise Modelling of Wave Energy Devices
NONE
2009-07-01
Future large-scale implementation of wave energy converts (WECs) will introduce an anthropogenic activity in the ocean which may contribute to underwater noise. The Ocean houses several marine species with acoustic sensibility; consequently the potential impact of the underwater noise needs to be addressed. At present, there are no acoustic impact studies based on acquired data. The WEAM project (Wave Energy Acoustic Monitoring) aims at developing an underwater noise monitoring plan for WECs. The development of an acoustic monitoring plan must consider the sound propagation in the ocean, identify noise sources, understand the operational characteristics and select adequate instrumentation. Any monitoring strategy must involve in-situ measurements. However, the vast distances which sound travels within the ocean, can make in-situ measurements covering the entire area of interest, impracticable. This difficulty can be partially overcome through acoustic numerical modelling. This paper presents a synthetic study, on the application of acoustic forward modelling and the evaluation of the impact of noise produced by wave energy devices on marine mammals using criteria based on audiograms of dolphins, or other species. The idea is to illustrate the application of that methodology, and to show to what extent it allows for estimating distances of impacts due to acoustic noise.
19. Acoustic comfort in large dining spaces
Chen, X.; Kang, J
2017-01-01
© 2016 Elsevier Ltd This study carried out a questionnaire field investigation in two typical large dining spaces. The results suggest that the acoustic comfort of diners has an influence on the comfort evaluation of the overall dining environment, and background noise is an important factor affecting the acoustic comfort evaluation of diners. The role of various individual sound sources in background noise has been investigated, considering general background music, speech sound, activity so...
20. Experimental Acoustic Evaluation of an Auditorium
Marina Dana Ţopa
2012-01-01
Full Text Available The paper presents a case history: the acoustical analysis of a rectangular auditorium. The following acoustical parameters were evaluated: early decay time, reverberation time, clarity, definition, and center time. The excitation signal was linear sweep sine and additional analysis was carried out: peak-to-noise ratio, reverberation time for empty and occupied room, standard deviation of acoustical parameters, diffusion, and just noticeable differences analysis. Conclusions about room’s destination and modeling were drawn in the end.
1. An acoustical model based monitoring network
Wessels, P.W.; Basten, T.G.H.; Eerden, F.J.M. van der
2010-01-01
In this paper the approach for an acoustical model based monitoring network is demonstrated. This network is capable of reconstructing a noise map, based on the combination of measured sound levels and an acoustic model of the area. By pre-calculating the sound attenuation within the network the noi
Turner, Travis L.; Rizzi, Stephen A.
1995-01-01
Interior noise and sonic fatigue are important issues in the development and design of advanced subsonic and supersonic aircraft. Conventional aircraft typically employ passive treatments, such as constrained layer damping and acoustic absorption materials, to reduce the structural response and resulting acoustic levels in the aircraft interior. These techniques require significant addition of mass and only attenuate relatively high frequency noise transmitted through the fuselage. Although structural acoustic coupling is in general very important in the study of aircraft fuselage interior noise, analysis of noise transmission through a panel supported in an infinite rigid baffle (separating two semi-infinite acoustic domains) can be useful in evaluating the effects of active/adaptive materials, complex loading, etc. Recent work has been aimed at developing adaptive and/or active methods of controlling the structural acoustic response of panels to reduce the transmitted noise1. A finite element formulation was recently developed to study the dynamic response of shape memory alloy (SMA) hybrid composite panels (conventional composite panel with embedded SMA fibers) subject to combined acoustic and thermal loads2. Further analysis has been performed to predict the far-field acoustic radiation using the finite element dynamic panel response prediction3. The purpose of the present work is to validate the panel vibration and acoustic radiation prediction methods with baseline experimental results obtained from an isotropic panel, without the effect of SMA.
3. Objective and subjective evaluation of the acoustic comfort in classrooms.
Zannin, Paulo Henrique Trombetta; Marcon, Carolina Reich
2007-09-01
The acoustic comfort of classrooms in a Brazilian public school has been evaluated through interviews with 62 teachers and 464 pupils, measurements of background noise, reverberation time, and sound insulation. Acoustic measurements have revealed the poor acoustic quality of the classrooms. Results have shown that teachers and pupils consider the noise generated and the voice of the teacher in neighboring classrooms as the main sources of annoyance inside the classroom. Acoustic simulations resulted in the suggestion of placement of perforated plywood on the ceiling, for reduction in reverberation time and increase in the acoustic comfort of the classrooms.
4. Subjective evaluation of restaurant acoustics in a virtual sound environment
Nielsen, Nicolaj Østergaard; Marschall, Marton; Santurette, Sébastien
2016-01-01
surveys report that noise complaints are on par with poor service. This study investigated the relation between objective acoustic parameters and subjective evaluation of acoustic comfort at five restaurants in terms of three parameters: noise annoyance, speech intelligibility, and privacy. At each...... location, customers filled out questionnaire surveys, acoustic parameters were measured, and recordings of restaurant acoustic scenes were obtained with a 64-channel spherical array. The acoustic scenes were reproduced in a virtual sound environment (VSE) with 64 loudspeakers placed in an anechoic room...
5. THE ACOUSTIC CONTAMINATION OF SCHOOL ENVIRONMENT DUE TO URBAN NOISES IN THE FEDERAL DISTRICT, BRASIL = A CONTAMINAÇÃO ACÚSTICA DE AMBIENTES ESCOLARES DEVIDO AOS RUÍDOS URBANOS NO DISTRITO FEDERAL, BRASIL
Alexandre Eniz
2006-01-01
Full Text Available Urban noises are more and more presents in our daily life, invading residences, work places, leisure locations, hospitals and schools, becoming a potential harm to social interaction, communication, behavior, school performance, health etc. The main objective of this work was to analyze and quantify the environmental noise in ten schools of the basic education in District Federal, Brazil. The adopted parameter was the equivalent sound pressure level Leq (A, which was evaluated according to the sound level measures following the standard established by Brazilian Association of echnical Regulations (ABNT. The background noise was measured during holidays and during regular class periods. The study detected that half of the schools researched are being “contaminated” with noise from aircraft, road traffic, trucks, advertising vehicles, motorcycles, buses among other sources, with limits outside the recommended by law. In 90% of the evaluated schools, the noise levels observed during the activities are above of the maximum values recommended for the acoustic comfort of a school. These are buildings ill-located in the city and therefore “exposed” to levels that are above of recommended by the norms. The results show a critical situation indicating the urgent need of actions with the objective of mitigating this severe type of pollution. = Os ruídos urbanos estão cada vez mais presentes em nosso cotidiano, invadindo residências, locais de trabalho, de lazer, hospitais e escolas, podendo prejudicar as relações sociais, a comunicação, o comportamento, o rendimento escolar, a saúde etc. O objetivo principal deste trabalho foi analisar e quantificar o ruído ambiental em dez escolas do Ensino Fundamental e Médio no Distrito Federal. O parâmetro adotado foi o nível de pressão sonora equivalente Leq (A, avaliado por medidores de pressão sonora, segundo as normas estabelecidas pela Associação Brasileira de NormasTécnicas (ABNT. O ru
6. Aircraft Noise Prediction
2014-01-01
This contribution addresses the state-of-the-art in the field of aircraft noise prediction, simulation and minimisation. The point of view taken in this context is that of comprehensive models that couple the various aircraft systems with the acoustic sources, the propagation and the flight trajectories. After an exhaustive review of the present predictive technologies in the relevant fields (airframe, propulsion, propagation, aircraft operations, trajectory optimisation), the paper add...
7. Acoustical quality in office workstations, as assed by occupant surveys
Jensen, Kasper Lynge
2005-01-01
We analyzed acoustic satisfaction in office environments in buildings surveyed by The Center For The Built Environment (CBE). A total of 23,450 respondents from 142 buildings were included in the analysis. Acoustic satisfaction in the CBE survey is a function of satisfaction with both noise...... and speech privacy. In the database people are significantly more dissatisfied with speech privacy than noise level (P offices are significantly more satisfied with the acoustics than occupants in cubicles (P...
8. Vibration and acoustic environments for payload/cargo integration
Hill, R. E.; Coody, M. C.
1983-01-01
Shuttle orbiter launch vibration and acoustic environments for cargo bay/payload interfaces are predicted. Data acquired during Shuttle flight tests are compared with the preflight estimates. Vibration response data for payload attachment locations are presented, along with acoustic data in the form of noise-level spectra measured at various locations in the cargo bay and space averages of the noise levels. It is shown that the payload-bay vibration and acoustic environments are generally less severe than predicted.
9. New opportunities for aircraft noise policy in the Netherlands
Kroesen, M.
2010-01-01
This papers aims (1) to provide a review of the (non-acoustic) social-psychological determinants of aircraft noise annoyance, (2) evaluate Schiphol’s noise policy from a social-psychological perspective and (3) review a governance model that can effectively address non-acoustic factors in aircraft n
10. Reduction of turbomachinery noise
Waitz, Ian A. (Inventor); Brookfield, John M. (Inventor); Sell, Julian (Inventor); Hayden, Belva J. (Inventor); Ingard, K. Uno (Inventor)
1999-01-01
11. Study of airfoil trailing edge bluntness noise
Zhu, Wei Jun; Shen, Wen Zhong; Sørensen, Jens Nørkær
2010-01-01
This paper deals with airfoil trailing edge noise with special focus on airfoils with blunt trailing edges. Two methods are employed to calculate airfoil noise: The flow/acoustic splitting method and the semi-empirical method. The flow/acoustic splitting method is derived from compressible Navier...... design or optimization. Calculations from both methods are compared with exist experiments. The airfoil blunt noise is found as a function of trailing edge bluntness, Reynolds number, angle of attack, etc.......-Stokes equations. It provides us possibilities to study details about noise generation mechanism. The formulation of the semi-empirical model is based on acoustic analogy and then curve-fitted with experimental data. Due to its high efficiency, such empirical relation is used for purpose of low noise airfoil...
12. Longitudinal bulk acoustic mass sensor
Hales, Jan Harry; Teva, Jordi; Boisen, Anja
2009-01-01
A polycrystalline silicon longitudinal bulk acoustic cantilever is fabricated and operated in air at 51 MHz. A mass sensitivity of 100 Hz/fg (1 fg=10(-15) g) is obtained from the preliminary experiments where a minute mass is deposited on the device by means of focused ion beam. The total noise i...
13. Acoustic Climb to Cruise Test
1991-01-01
Flight test film footage of three different aircraft testing the acoustical noise levels during take-off, climb, maneuvers, and touch and go landings are described. These sound tests were conducted on two fighter aircraft and one cargo aircraft. Results from mobile test vehicle are shown.
14. Acoustical Imaging
Litniewski, Jerzy; Kujawska, Tamara; 31st International Symposium on Acoustical Imaging
2012-01-01
The International Symposium on Acoustical Imaging is a unique forum for advanced research, covering new technologies, developments, methods and theories in all areas of acoustics. This interdisciplinary Symposium has been taking place continuously since 1968. In the course of the years the proceedings volumes in the Acoustical Imaging Series have become a reference for cutting-edge research in the field. In 2011 the 31st International Symposium on Acoustical Imaging was held in Warsaw, Poland, April 10-13. Offering both a broad perspective on the state-of-the-art as well as in-depth research contributions by the specialists in the field, this Volume 31 in the Series contains an excellent collection of papers in six major categories: Biological and Medical Imaging Physics and Mathematics of Acoustical Imaging Acoustic Microscopy Transducers and Arrays Nondestructive Evaluation and Industrial Applications Underwater Imaging
15. Acoustic biosensors
Fogel, Ronen; Limson, Janice; Seshia, Ashwin A.
2016-01-01
Resonant and acoustic wave devices have been researched for several decades for application in the gravimetric sensing of a variety of biological and chemical analytes. These devices operate by coupling the measurand (e.g. analyte adsorption) as a modulation in the physical properties of the acoustic wave (e.g. resonant frequency, acoustic velocity, dissipation) that can then be correlated with the amount of adsorbed analyte. These devices can also be miniaturized with advantages in terms of ...
16. Multilevel multi-integration algorithm for acoustics
Hernández Ramírez, Isaías
2005-01-01
In acoustics the study of the prediction of noise and its possible consequences has tremendously gained in importance in the past decades. A low noise level has become an essential quality as well as a marketing advantage for products and installations. For guidance in the design of silent products
17. Noise Characteristics of a Four-Jet Impingement Device Inside a Broadband Engine Noise Simulator
Brehm, Christoph; Housman, Jeffrey A.; Kiris, Cetin C.; Hutcheson, Florence V.
2015-01-01
The noise generation mechanisms for four directly impinging supersonic jets are investigated employing implicit large eddy simulations with a higher-order accurate weighted essentially non-oscillatory shock-capturing scheme. Impinging jet devices are often used as an experimental apparatus to emulate a broadband noise source. Although such devices have been used in many experiments, a detailed investigation of the noise generation mechanisms has not been conducted before. Thus, the underlying physical mechanisms that are responsible for the generation of sound waves are not well understood. The flow field is highly complex and contains a wide range of temporal and spatial scales relevant for noise generation. Proper orthogonal decomposition of the flow field is utilized to characterize the unsteady nature of the flow field involving unsteady shock oscillations, large coherent turbulent flow structures, and the sporadic appearance of vortex tubes in the center of the impingement region. The causality method based on Lighthill's acoustic analogy is applied to link fluctuations of flow quantities inside the source region to the acoustic pressure in the far field. It will be demonstrated that the entropy fluctuation term in the Lighthill's stress tensor plays a vital role in the noise generation process. Consequently, the understanding of the noise generation mechanisms is employed to develop a reduced-order linear acoustic model of the four-jet impingement device. Finally, three linear acoustic FJID models are used as broadband noise sources inside an engine nacelle and the acoustic scattering results are validated against far-field acoustic experimental data.
18. North Pacific Acoustic Laboratory: Deep Water Acoustic Propagation in the Philippine Sea
2014-09-30
acoustic predictions and for understanding the local ocean dynamics, (iii) improving our understanding of the physics of scattering by internal waves ...the scattering of the acoustic signals by ocean internal waves and/or spice (Dzieciuch, 2014). The procedure consisted of pulse compression of the...ambient noise field, and (v) understanding the relationship between the acoustic field in the water column and the seismic field in the seafloor for both
19. Student design projects in applied acoustics.
Bös, Joachim; Moritz, Karsten; Skowronek, Adam; Thyes, Christian; Tschesche, Johannes; Hanselka, Holger
2012-03-01
This paper describes a series of student projects which are intended to complement theoretical education in acoustics and engineering noise control with practical experience. The projects are also intended to enhance the students' ability to work in a team, to manage a project, and to present their results. The projects are carried out in close cooperation with industrial partners so that the students can get a taste of the professional life of noise control engineers. The organization of such a project, its execution, and some of the results from the most recent student project are presented as a demonstrative example. This latest project involved the creation of noise maps of a production hall, the acoustic analysis of a packaging machine, and the acoustic analysis of a spiral vibratory conveyor. Upon completion of the analysis, students then designed, applied, and verified some simple preliminary noise reduction measures to demonstrate the potential of these techniques.
Lyamshev, Leonid M
2004-01-01
1. High‐order numerical simulations of flow‐induced noise
Zhu, Wei Jun; Shen, Wen Zhong; Sørensen, Jens Nørkær
2011-01-01
In this paper, the flow/acoustics splitting method for predicting flow‐generated noise is further developed by introducing high‐order finite difference schemes. The splitting method consists of dividing the acoustic problem into a viscous incompressible flow part and an inviscid acoustic part...... are used for the spatial discretizations. Applications and validations of the new acoustics solver are presented for benchmark aeroacoustic problems and for flow over an NACA 0012 airfoil. Copyright © 2010 John Wiley & Sons, Ltd....
2. ACOUSTIC EMISSION ANALYZER
J. J. Almeida-Pérez
2004-12-01
Full Text Available In this paper appears a solution for acoustic emission analysis commonly known as noise. For the accomplishmentof this work a personal computer is used, besides sensors (microphones and boards designed and built for signalconditioning. These components are part of a virtual instrument used for monitoring the acoustical emission. Themain goal of this work is to develop a virtual instrument that supplies many important data as the result of ananalysis allowing to have information in an easy and friendly way. Moreover this information is very useful forstudying and resolving several situations in planning, production and testing areas.The main characteristics of the virtual instrument are: signal analysis in time, effective power measurement inDecibels (dB, average intensity taken from the principle of paired microphones, as well as the data analysis infrequency. These characteristics are included to handle two information channels.
3. Aero-Acoustic Moldeling using Large Eddy Simulation
Shen, Wen Zhong; Sørensen, Jens Nørkær
2008-01-01
The flow-acoustic splitting technique for aero-acoustic computations is extended to simulate the propagation of acoustic waves generated by three-dimensional turbulent flows. In the flow part, a sub-grid-scale turbulence model (the mixed model) is employed for Large-Eddy Simulations. The obtained...... instantaneous flow solution is employed as input for the acoustic part. At low Mach numbers the differences in scales and propagation speed between the flow and the acoustic field are quite large, hence different meshes and time-steps can be utilized for the two parts. The model is applied to compute flows past...... characteristics for angles of attack up to stall. For the acoustic solutions, predicted noise spectra are validated quantitatively against the experimental data of Brook et al. A parametrical study of the noise pattern for flows at angles of attack between 4 deg and 12 deg shows that the noise level is small...
4. Numerical Noise Prediction in Fluid Machinery
Iris PANTLE; Franco MAGAGNATO; Martin GABI
2005-01-01
Numerical methods successively became important in the design and optimization of fluid machinery. However,as noise emission is considered, one can hardly find standardized prediction methods combining flow and acoustical optimization. Several numerical field methods for sound calculations have been developed. Due to the complexity of the considered flow, approaches must be chosen to avoid exhaustive computing. In this contribution the noise of a simple propeller is investigated. The configurations of the calculations comply with an existing experimental setup chosen for evaluation. The used in-house CFD solver SPARC contains an acoustic module based on Ffowcs Williams-Hawkings Acoustic Analogy. From the flow results of the time dependent Large Eddy Simulation the time dependent acoustic sources are extracted and given to the acoustic module where relevant sound pressure levels are calculated. The difficulties, which arise while proceeding from open to closed rotors and from gas to liquid are discussed.
5. Acoustical Considerations in Planning and Design of Library Facilities.
Wrightson, Denelle; Wrightson, John M.
1999-01-01
Discusses acoustical demands in public libraries to consider during the design and construction process of new or renovated library space. Topics include intrusive noises; overly reverberant spaces; lack of speech privacy; sound transmission class; noise criteria; reverberation time and noise reduction coefficient; space planning; sound systems;…
6. Noise environment reduction foam spheres in space
Scharton, Terry; Kern, Dennis; Badilla, Gloria
1989-01-01
The advent of lightweight fairings for new spacecraft and the increased thrust of new launch vehicles have intensified the need for better techniques for predicting and for reducing the low frequency noise environment of spacecraft at liftoff. This paper presents a VAPEPS (VibroAcoustic Payload Environment Prediction System) parametrical analysis of the noise reduction of spacecraft fairings and explores a novel technique for increasing the low frequency noise reduction of lightweight fairing by approximately 10 dB.
7. XV-15 Low-Noise Terminal Area Operations Testing
Edwards, B. D.
1998-01-01
Test procedures related to XV-15 noise tests conducted by NASA-Langley and Bell Helicopter Textron, Inc. are discussed. The tests. which took place during October and November 1995, near Waxahachie, Texas, documented the noise signature of the XV-15 tilt-rotor aircraft at a wide variety of flight conditions. The stated objectives were to: -provide a comprehensive acoustic database for NASA and U.S. Industry -validate noise prediction methodologies, and -develop and demonstrate low-noise flight profiles. The test consisted of two distinct phases. Phase 1 provided an acoustic database for validating analytical noise prediction techniques; Phase 2 directly measured noise contour information at a broad range of operating profiles, with emphasis on minimizing 'approach' noise. This report is limited to a documentation of the test procedures, flight conditions, microphone locations, meteorological conditions, and test personnel used in the test. The acoustic results are not included.
8. Acoustical Imaging
Akiyama, Iwaki
2009-01-01
The 29th International Symposium on Acoustical Imaging was held in Shonan Village, Kanagawa, Japan, April 15-18, 2007. This interdisciplinary Symposium has been taking place every two years since 1968 and forms a unique forum for advanced research, covering new technologies, developments, methods and theories in all areas of acoustics. In the course of the years the volumes in the Acoustical Imaging Series have developed and become well-known and appreciated reference works. Offering both a broad perspective on the state-of-the-art in the field as well as an in-depth look at its leading edge research, this Volume 29 in the Series contains again an excellent collection of seventy papers presented in nine major categories: Strain Imaging Biological and Medical Applications Acoustic Microscopy Non-Destructive Evaluation and Industrial Applications Components and Systems Geophysics and Underwater Imaging Physics and Mathematics Medical Image Analysis FDTD method and Other Numerical Simulations Audience Researcher...
9. Battlefield acoustics
Damarla, Thyagaraju
2015-01-01
This book presents all aspects of situational awareness in a battlefield using acoustic signals. It starts by presenting the science behind understanding and interpretation of sound signals. The book then goes on to provide various signal processing techniques used in acoustics to find the direction of sound source, localize gunfire, track vehicles, and detect people. The necessary mathematical background and various classification and fusion techniques are presented. The book contains majority of the things one would need to process acoustic signals for all aspects of situational awareness in one location. The book also presents array theory, which is pivotal in finding the direction of arrival of acoustic signals. In addition, the book presents techniques to fuse the information from multiple homogeneous/heterogeneous sensors for better detection. MATLAB code is provided for majority of the real application, which is a valuable resource in not only understanding the theory but readers, can also use the code...
10. Acoustics Research
National Oceanic and Atmospheric Administration, Department of Commerce — Fisheries acoustics data are collected from more than 200 sea-days each year aboard the FRV DELAWARE II and FRV ALBATROSS IV (decommissioned) and the FSV Henry B....
11. Room Acoustics
Kuttruff, Heinrich; Mommertz, Eckard
The traditional task of room acoustics is to create or formulate conditions which ensure the best possible propagation of sound in a room from a sound source to a listener. Thus, objects of room acoustics are in particular assembly halls of all kinds, such as auditoria and lecture halls, conference rooms, theaters, concert halls or churches. Already at this point, it has to be pointed out that these conditions essentially depend on the question if speech or music should be transmitted; in the first case, the criterion for transmission quality is good speech intelligibility, in the other case, however, the success of room-acoustical efforts depends on other factors that cannot be quantified that easily, not least it also depends on the hearing habits of the listeners. In any case, absolutely "good acoustics" of a room do not exist.
12. Acoustic design of rotor blades using a genetic algorithm
Wells, V. L.; Han, A. Y.; Crossley, W. A.
1995-01-01
A genetic algorithm coupled with a simplified acoustic analysis was used to generate low-noise rotor blade designs. The model includes thickness, steady loading and blade-vortex interaction noise estimates. The paper presents solutions for several variations in the fitness function, including thickness noise only, loading noise only, and combinations of the noise types. Preliminary results indicate that the analysis provides reasonable assessments of the noise produced, and that genetic algorithm successfully searches for 'good' designs. The results show that, for a given required thrust coefficient, proper blade design can noticeably reduce the noise produced at some expense to the power requirements.
13. Optimizing Noise Attenuation in Aircraft Exhaust Ducts Employing Passive and Active Absorbing Splitters and Struts Project
National Aeronautics and Space Administration — NASA requires accurate numerical simulation of high bypass nacelle acoustics and the development of advanced nacelle absorption techniques to reduce engine noise...
14. Acoustic simulation of a patient's obstructed airway.
van der Velden, W C P; van Zuijlen, A H; de Jong, A T; Lynch, C T; Hoeve, L J; Bijl, H
2016-01-01
This research focuses on the numerical simulation of stridor; a high pitched, abnormal noise, resulting from turbulent airflow and vibrating tissue through a partially obstructed airway. Characteristics of stridor noise are used by medical doctors as indication for location and size of the obstruction. The relation between type of stridor and the various diseases associated with airway obstruction is unclear; therefore, simply listening to stridor is an unreliable diagnostic tool. The overall aim of the study is to better understand the relationship between characteristics of stridor noise and localization and size of the obstruction. Acoustic analysis of stridor may then in future simplify the diagnostic process, and reduce the need for more invasive procedures such as laryngoscopy under general anesthesia. In this paper, the feasibility of a coupled flow, acoustic and structural model is investigated to predict the noise generated by the obstruction as well as the propagation of the noise through the airways, taking into account a one-way coupled fluid, structure, and acoustic interaction components. The flow and acoustic solver are validated on a diaphragm and a simplified airway model. A realistic airway model of a patient suffering from a subglottic stenosis, derived from a real computed tomography scan, is further analyzed. Near the mouth, the broadband noise levels at higher frequencies increased with approximately 15-20 dB comparing the stridorous model with the healthy model, indicating stridorous sound.
15. Acoustics, computers and measurements
Truchard, James J.
2003-10-01
The human ear has created a high standard for the requirements of acoustical measurements. The transient nature of most acoustical signals has limited the success of traditional volt meters. Professor Hixson's pioneering work in electroacoustical measurements at ARL and The University of Texas helped set the stage for modern computer-based measurements. The tremendous performance of modern PCs and extensive libraries of signal processing functions in virtual instrumentation application software has revolutionized the way acoustical measurements are made. Today's analog to digital converters have up to 24 bits of resolution with a dynamic range of over 120 dB and a single PC processor can process 112 channels of FFTs at 4 kHz in real time. Wavelet technology further extends the capabilities for analyzing transients. The tools available for measurements in speech, electroacoustics, noise, and vibration represent some of the most advanced measurement tools available. During the last 50 years, Professor Hixson has helped drive this revolution from simple oscilloscope measurements to the modern high performance computer-based measurements.
16. Introducing passive acoustic filter in acoustic based condition monitoring: Motor bike piston-bore fault identification
Jena, D. P.; Panigrahi, S. N.
2016-03-01
Requirement of designing a sophisticated digital band-pass filter in acoustic based condition monitoring has been eliminated by introducing a passive acoustic filter in the present work. So far, no one has attempted to explore the possibility of implementing passive acoustic filters in acoustic based condition monitoring as a pre-conditioner. In order to enhance the acoustic based condition monitoring, a passive acoustic band-pass filter has been designed and deployed. Towards achieving an efficient band-pass acoustic filter, a generalized design methodology has been proposed to design and optimize the desired acoustic filter using multiple filter components in series. An appropriate objective function has been identified for genetic algorithm (GA) based optimization technique with multiple design constraints. In addition, the sturdiness of the proposed method has been demonstrated in designing a band-pass filter by using an n-branch Quincke tube, a high pass filter and multiple Helmholtz resonators. The performance of the designed acoustic band-pass filter has been shown by investigating the piston-bore defect of a motor-bike using engine noise signature. On the introducing a passive acoustic filter in acoustic based condition monitoring reveals the enhancement in machine learning based fault identification practice significantly. This is also a first attempt of its own kind.
17. FLOW NOISE MEASUREMENT OF SURFACE SHIP WITH TOWED MODEL
2008-01-01
In this article, a new acoustic test technique using towed model was introduced to study flow noise caused by a surface ship. The project of model test was be properly designed for acoustic signal collecting and with the help of appropriate data processing method different kinds of acoustic sources could be successfully identified. A lot of work about fuid noise could be carried on with the towed model, and the noise corresponding to low frequency which is especially interested for its long distance radiating with small attenuation could also be studied in this way.
18. Noise-induced hearing loss
Mariola Sliwinska-Kowalska
2012-01-01
Full Text Available Noise-induced hearing loss (NIHL still remains a problem in developed countries, despite reduced occupational noise exposure, strict standards for hearing protection and extensive public health awareness campaigns. Therefore NIHL continues to be the focus of noise research activities. This paper summarizes progress achieved recently in our knowledge of NIHL. It includes papers published between the years 2008-2011 (in English, which were identified by a literature search of accessible medical and other relevant databases. A substantial part of this research has been concerned with the risk of NIHL in the entertainment sector, particularly in professional, orchestral musicians. There are also constant concerns regarding noise exposure and hearing risk in "hard to control" occupations, such as farming and construction work. Although occupational noise has decreased since the early 1980s, the number of young people subject to social noise exposure has tripled. If the exposure limits from the Noise at Work Regulations are applied, discotheque music, rock concerts, as well as music from personal music players are associated with the risk of hearing loss in teenagers and young adults. Several recent research studies have increased the understanding of the pathomechanisms of acoustic trauma, the genetics of NIHL, as well as possible dietary and pharmacologic otoprotection in acoustic trauma. The results of these studies are very promising and offer grounds to expect that targeted therapies might help prevent the loss of sensory hair cells and protect the hearing of noise-exposed individuals. These studies emphasize the need to launch an improved noise exposure policy for hearing protection along with developing more efficient norms of NIHL risk assessment.
19. Acoustic Localization with Infrasonic Signals
Threatt, Arnesha; Elbing, Brian
2015-11-01
Numerous geophysical and anthropogenic events emit infrasonic frequencies (wind turbines and tornadoes. These sounds, which cannot be heard by the human ear, can be detected from large distances (in excess of 100 miles) due to low frequency acoustic signals having a very low decay rate in the atmosphere. Thus infrasound could be used for long-range, passive monitoring and detection of these events. An array of microphones separated by known distances can be used to locate a given source, which is known as acoustic localization. However, acoustic localization with infrasound is particularly challenging due to contamination from other signals, sensitivity to wind noise and producing a trusted source for system development. The objective of the current work is to create an infrasonic source using a propane torch wand or a subwoofer and locate the source using multiple infrasonic microphones. This presentation will present preliminary results from various microphone configurations used to locate the source.
20. Developing active noise control systems for noise attenuation in ducts
Campos, Rosely V.; Ivo, Rodrigo C.; Medeiros, Eduardo B.
2002-11-01
The present work describes some of the research effort on Active Noise Control (ANC) being jointly developed by the Catholic University of Minas Gerais (PUC-MINAS) and the Federal University of Minas Gerais (UFMG). Considerations about the implementation of Digital Signal Processing for noise control in ducts has been presented. The objective is to establish a study on Active Noise Control in ducts combining geometry and acoustic parameters modification together with adaptive digital filtering implementation. Both algorithm and digital signal processing details are also discussed. The main results for a typical application where real attenuation has been obtained are presented and considered according to their use in developing real applications. The authors also believe that the present text should provide an interesting overview for both designers and students concerned about Active Noise Control in ducts. (To be presented in Portuguese.)
1. Uncertainty analysis in acoustic investigations
2013-01-01
The problem of uncertainty assessment in acoustic investigations is presented in the hereby paper. The aspect of the uncertainty asymmetry in processing of data obtained in the measuring test of sound levels, determined in decibels, was sketched. On the basis of the analysis of data obtained in the continuous monitoring of road traffic noise in Krakow typical probability distributions for a day, evening and night were determined. The method of the uncertainty assessment based on the propagati...
2. Noise Estimation and Noise Removal Techniques for Speech Recognition in Adverse Environment
Shrawankar, Urmila; Thakare, Vilas
2010-01-01
International audience; Noise is ubiquitous in almost all acoustic environments. The speech signal, that is recorded by a microphone is generally infected by noise originating from various sources. Such contamination can change the characteristics of the speech signals and degrade the speech quality and intelligibility, thereby causing significant harm to human-to-machine communication systems. Noise detection and reduction for speech applications is often formulated as a digital filtering pr...
3. Noise Reduction with Microphone Arrays for Speaker Identification
Cohen, Z
2011-12-22
Reducing acoustic noise in audio recordings is an ongoing problem that plagues many applications. This noise is hard to reduce because of interfering sources and non-stationary behavior of the overall background noise. Many single channel noise reduction algorithms exist but are limited in that the more the noise is reduced; the more the signal of interest is distorted due to the fact that the signal and noise overlap in frequency. Specifically acoustic background noise causes problems in the area of speaker identification. Recording a speaker in the presence of acoustic noise ultimately limits the performance and confidence of speaker identification algorithms. In situations where it is impossible to control the environment where the speech sample is taken, noise reduction filtering algorithms need to be developed to clean the recorded speech of background noise. Because single channel noise reduction algorithms would distort the speech signal, the overall challenge of this project was to see if spatial information provided by microphone arrays could be exploited to aid in speaker identification. The goals are: (1) Test the feasibility of using microphone arrays to reduce background noise in speech recordings; (2) Characterize and compare different multichannel noise reduction algorithms; (3) Provide recommendations for using these multichannel algorithms; and (4) Ultimately answer the question - Can the use of microphone arrays aid in speaker identification?
4. Analysis tools for the design of active structural acoustic control systems
Oude Nijhuis, Marco Hendrikus Hermanus
2003-01-01
Acoustic noise is an important problem in the modern society and provides much of the impetus for the development of noise reduction techniques. Passive methods, such as the use of sound absorbing materials, provide an adequate solution to many noise problems, but for noise reduction at low frequenc
5. Curing the noise epidemic
Mazer, Susan
2005-09-01
The argument is made that design does not stop when the fixed architectural and acoustical components are in place. Spaces live and breathe with the people who reside in them. Research and examples are presented that show that noise, auditory clutter, thrives on itself in hospitals. Application of the Lombard reflex studies fit into the hospital setting, but do not offer solutions as to how one might reduce the impact. In addition, the basis for looking at the noise component as a physical as well cultural dynamic will be addressed. Whether the result of the wrong conversation in the wrong place or the right conversation in an unfortunate place, talk mixed with sounds of technology is shown to cause its own symptoms. From heightened anxiety and stress to medical errors, staff burnout, or HIPAA violations, the case is made that noise is pandemic in hospitals and demands financial and operational investment. An explanation of how to reduce noise by design of the dynamic environment - equipment, technology, staff protocols is also provided.
6. International Conference on Acoustics and Vibration
2017-01-01
The book provides readers with a snapshot of recent research and industrial trends in field of industrial acoustics and vibration. Each chapter, accepted after a rigorous peer-review process, reports on a selected, original piece of work presented and discussed at International Conference on Acoustics and Vibration (ICAV2016), which was organized by the Tunisian Association of Industrial Acoustics and Vibration (ATAVI) and held March 21-23, in Hammamet, Tunisia. The contributions, mainly written by north African authors, covers advances in both theory and practice in a variety of subfields, such as: smart materials and structures; fluid-structure interaction; structural acoustics as well as computational vibro-acoustics and numerical methods. Further topics include: engines control, noise identification, robust design, flow-induced vibration and many others.This book provides a valuable resource for both academics and professionals dealing with diverse issues in applied mechanics. By combining advanced theori...
7. Software for neutrino acoustic detection and localization
Bouhadef, B. [INFN Sezione Pisa, Polo Fibonacci, Largo Bruno Pontecorvo 3, 56127 Pisa (Italy); Dipartimento di Fisica, ' E. Fermi' University of Pisa, Largo Pontecorvo 3, 56127 Pisa (Italy)], E-mail: [email protected]
2009-06-01
The evidence of the existing of UHE (E>10{sup 19}eV) cosmic rays and its possible connection to UHE neutrino suggests the building of an acoustic telescope for neutrino, exploiting thermo-acoustic effect. We present software for neutrino acoustic signal detection and localization. The main points discussed here are the sea noise model, the determination of time differences of arrival (TDOA) between hydrophones signals, the source localization algorithm, and the telescope geometry effect. The effect of TDOAs errors and telescope geometry on the localization accuracy is also discussed.
8. Droplets Acoustics
Dahan, Raphael; Carmon, Tal
2015-01-01
Contrary to their capillary resonances (Rayleigh, 1879) and their optical resonances (Ashkin, 1977), droplets acoustical resonances were rarely considered. Here we experimentally excite, for the first time, the acoustical resonances of a droplet that relies on sound instead of capillary waves. Droplets vibrations at 37 MHz rates and 100 quality factor are optically excited and interrogated at an optical threshold of 68 microWatt. Our vibrations span a spectral band that is 1000 times higher when compared with drops previously-studied capillary vibration.
9. Reduction of Guided Acoustic Wave Brillouin Scattering in Photonic Crystal Fibers
Elser, D; Gloeckl, O; Korn, A; Leuchs, G; Lorenz, S; Marquardt, C; Marquardt, Ch.
2005-01-01
Guided Acoustic Wave Brillouin Scattering (GAWBS) generates phase and polarization noise of light propagating in glass fibers. This excess noise affects the performance of various experiments operating at the quantum noise limit. We experimentally demonstrate the reduction of GAWBS noise in a photonic crystal fiber in a broad frequency range using cavity sound dynamics. We compare the noise spectrum to the one of a standard fiber and observe a roughly 10-fold noise reduction in the frequency range up to 200 MHz.
10. Acoustic source data for medium speed IC-engines
Hynninen, A.; Turunen, R.; Åbom, Mats; Bodén, Hans
2011-01-01
Knowledge of the acoustic source characteristics of internal combustion engines (IC-engines) is of great importance when designing the exhaust duct system and its components to withstand the resulting dynamic loads and to reduce the exhaust noise emission. Number of studies has been published earlier on the low frequency in-duct exhaust noise of high speed engines. The goal of the present study is to investigate the medium speed IC-engine acoustic source characteristics numerically and experi...
11. 11th International Workshop on Railway Noise
Anderson, David; Gautier, Pierre-Etienne; Iida, Masanobu; Nelson, James; Thompson, David; Tielkes, Thorsten; Towers, David; Vos, Paul
2015-01-01
The book reports on the 11th International Workshop on Railway Noise, held on 9 – 13 September, 2013, in Uddevalla, Sweden. The event, which was jointly organized by the Competence Centre Chalmers Railway Mechanics (CHARMEC) and the Departments of Applied Mechanics and Applied Acoustics at Chalmers University of Technology in Gothenburg, Sweden, covered a broad range of topics in the field of railway noise and vibration, including: prospects, legal regulations and perceptions; wheel and rail noise; prediction, measurements and monitoring; ground-borne vibration; squeal noise and structure-borne noise; and aerodynamic noise generated by high-speed trains. Further topics included: resilient track forms; grinding, corrugation and roughness; and interior noise and sound barriers. This book, which consists of a collection of peer-reviewed papers originally submitted to the workshop, not only provides readers with an overview of the latest developments in the field, but also offers scientists and engineers essent...
12. Combined sensor noise-immunity
Vladimir A. Shchurov; Alexander V. Shchurov
2002-01-01
The paper presents statistical analysis of combined sensor noise-immunity while recording fluctuating tone against underwater dynamic noise background. The experimental data used for the analysis have been collected by a pair of four-component combined sensors centered at two depths, 150 and 300 m in deep water. Expressions for combined sensor signalto-noise ratio (SNR) for cross-spectral levels of signal and noise for both wide and narrow frequency bands have been derived. A combined sensor gain has been introduced in terms of ordinary single-point coherence function between acoustic pressure and particle velocity in acoustic wave. The estimates obtained experimentally evidence that SNR for a combined sensor with multiplicative data processing may exceed SNR for a hydrophone-based sensor by 15 to 16 dB at most for the horizontal channel of the combined sensor, and by 30 dB at most for the vertical channel (when opposite energy flows of signal and noise compensate one another).
13. Effect of non-uniform mean flow field on acoustic propagation problems in computational aeroacoustics
Si, Haiqing; Shen, Wen Zhong; Zhu, Wei Jun
2013-01-01
Acoustic propagation in the presence of a non-uniform mean flow is studied numerically by using two different acoustic propagating models, which solve linearized Euler equations (LEE) and acoustic perturbation equations (APE). As noise induced by turbulent flows often propagates from near field t...
14. ROLLING NOISE SIMULATION OF A RAILWAY VEHICLE
Traian MAZILU
2013-05-01
Full Text Available Rolling noise of the railway vehicles is occurred by the wheel/rail vibration excited bythe rolling surfaces roughness. This paper presents an acoustic model able to predict the rollingnoise level of a railway vehicle. The acoustic model is based on a wheel/rail vibration modelwhich takes into account the structural wheel vibration (Remington model and the bendingvertical waves of the rail. To this, the track model with an infinite Euler Bernoulli beam elasticallysupported on two layers is applied to simulate the effect of the ballasted track. The influence of therolling surfaces roughness and vehicle velocity on the rolling noise is investigated.
15. Hybrid Analysis of Engine Core Noise
O'Brien, Jeffrey; Kim, Jeonglae; Ihme, Matthias
2015-11-01
Core noise, or the noise generated within an aircraft engine, is becoming an increasing concern for the aviation industry as other noise sources are progressively reduced. The prediction of core noise generation and propagation is especially challenging for computationalists since it involves extensive multiphysics including chemical reaction and moving blades in addition to the aerothermochemical effects of heated jets. In this work, a representative engine flow path is constructed using experimentally verified geometries to simulate the physics of core noise. A combustor, single-stage turbine, nozzle and jet are modeled in separate calculations using appropriate high fidelity techniques including LES, actuator disk theory and Ffowcs-Williams Hawkings surfaces. A one way coupling procedure is developed for passing fluctuations downstream through the flowpath. This method effectively isolates the core noise from other acoustic sources, enables straightforward study of the interaction between core noise and jet exhaust, and allows for simple distinction between direct and indirect noise. The impact of core noise on the farfield jet acoustics is studied extensively and the relative efficiency of different disturbance types and shapes is examined in detail.
16. The Development of the Acoustic Design of NASA Glenn Research Center's New Reverberant Acoustic Test Facility
Hughes, William O.; McNelis, Mark E.; Hozman, Aron D.; McNelis, Anne M.
2011-01-01
The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) is leading the design and build of the new world-class vibroacoustic test capabilities at the NASA GRC s Plum Brook Station in Sandusky, Ohio. Benham Companies, LLC is currently constructing modal, base-shake sine and reverberant acoustic test facilities to support the future testing needs of NASA s space exploration program. The large Reverberant Acoustic Test Facility (RATF) will be approximately 101,000 ft3 in volume and capable of achieving an empty chamber acoustic overall sound pressure level (OASPL) of 163 dB. This combination of size and acoustic power is unprecedented amongst the world s known active reverberant acoustic test facilities. The key to achieving the expected acoustic test spectra for a range of many NASA space flight environments in the RATF is the knowledge gained from a series of ground acoustic tests. Data was obtained from several NASA-sponsored test programs, including testing performed at the National Research Council of Canada s acoustic test facility in Ottawa, Ontario, Canada, and at the Redstone Technical Test Center acoustic test facility in Huntsville, Alabama. The majority of these tests were performed to characterize the acoustic performance of the modulators (noise generators) and representative horns that would be required to meet the desired spectra, as well as to evaluate possible supplemental gas jet noise sources. The knowledge obtained in each of these test programs enabled the design of the RATF sound generation system to confidently advance to its final acoustic design and subsequent on-going construction.
17. Three-dimensional nonlinear acoustical holography
Niu, Yaying
Nearfield Acoustical Holography (NAH) is an acoustic field visualization technique that can be used to reconstruct three-dimensional (3-D) acoustic fields by projecting two-dimensional (2-D) data measured on a hologram surface. However, linear NAH algorithms developed and improved by many researchers can result in significant reconstruction errors when they are applied to reconstruct 3-D acoustic fields that are radiated from a high-level noise source and include significant nonlinear components. Here, planar, nonlinear acoustical holography procedures are developed that can be used to reconstruct 3-D, nonlinear acoustic fields radiated from a high-level noise source based on 2-D acoustic pressure data measured on a hologram surface. The first nonlinear acoustic holography procedure is derived for reconstructing steady-state acoustic pressure fields by applying perturbation and renormalization methods to nonlinear, dissipative, pressure-based Westervelt Wave Equation (WWE). The nonlinear acoustic pressure fields radiated from a high-level pulsating sphere and an infinite-size, vibrating panel are used to validate this procedure. Although the WWE-based algorithm is successfully validated by those two numerical simulations, it still has several limitations: (1) Only the fundamental frequency and its second harmonic nonlinear components can be reconstructed; (2) the application of this algorithm is limited to mono-frequency source cases; (3) the effects of bent wave rays caused by transverse particle velocities are not included; (4) only acoustic pressure fields can be reconstructed. In order to address the limitations of the steady-state, WWE-based procedure, a transient, planar, nonlinear acoustic holography algorithm is developed that can be used to reconstruct 3-D nonlinear acoustic pressure and particle velocity fields. This procedure is based on Kuznetsov Wave Equation (KWE) that is directly solved by using temporal and spatial Fourier Transforms. When compared
18. Noise Caused by Cavitating Butterfly and Monovar Valves
HASSIS, H.
1999-08-01
An experimental study of the effects of cavitation was carried out through an analysis of cavitating Butterfly and Monovar values. Focus is particularly placed on both unsteady pressure and acoustic pressure fluctuations. In this paper, the effects of cavitation on local fluctuation pressure (turbulence), acoustic propagation (damping and sound velocity), resonance frequencies and level of noise are presented.
19. Coupled analysis of engine noise and interior noise of an automobile
郑旭; 毛杰; 郝志勇
2015-01-01
The coupled model of a four-cylinder internal combustion engine and a dash panel was constructed to analyze the relationship between the engine noise and interior noise of an automobile. Finite element analysis, flexible multi-body dynamics, and boundary element analysis were integrated to obtain the tetrahedron-element models, structural vibration response, and radiated noise, respectively. The accuracy of the finite-element model of the engine was validated by modal analysis via single-input multi-output technology, while the dash panel was validated by sound transmission loss experiment. The block was optimized to reduce the radiated acoustic power from the engine surface. The acoustic transfer path between the engine cabin and passenger compartment was then established. The coupled analysis results reveal that the interior noise is optimized due to the engine noise reduction.
20. Evaluation of the efficiency of the shields for reduction of airplane noise effects
В. Ф. Шило
1999-09-01
Full Text Available Acoustic shield is one of the most effective means for reduction of transport noise effect, aviation included. Noise shields are widely used in world practice. Acoustic efficiency of shields depends on many factors, therefore it is necessary to use, on the designing stage, complicated methodical and computer means for their substantiation
1. Control strategies for aircraft airframe noise reduction
Li Yong; Wang Xunnian; Zhang Dejiu
2013-01-01
With the development of low-noise aircraft engine,airframe noise now represents a major noise source during the commercial aircraft's approach to landing phase.Noise control efforts have therefore been extensively focused on the airframe noise problems in order to further reduce aircraft overall noise.In this review,various control methods explored in the last decades for noise reduction on airframe components including high-lift devices and landing gears are summarized.We introduce recent major achievements in airframe noise reduction with passive control methods such as fairings,deceleration plates,splitter plates,acoustic liners,slat cove cover and side-edge replacements,and then discuss the potential and control mechanism of some promising active flow control strategies for airframe noise reduction,such as plasma technique and air blowing/suction devices.Based on the knowledge gained throughout the extensively noise control testing,a few design concepts on the landing gear,high-lift devices and whole aircraft are provided for advanced aircraft low-noise design.Finally,discussions and suggestions are given for future research on airframe noise reduction.
2. Acoustics in mechanical engineering undergraduate core courses: Challenges and opportunities
2005-04-01
Generally in an undergraduate curriculum of mechanical engineering, acoustics is not included as a core course. The major core courses deal with mechanics, design, dynamics of machinery, etc. However, engineering aspects of acoustics or noise can be included through elective courses. Given the limited slots for elective courses in a curriculum, it is difficult to run elective courses in acoustics regularly with a required number of students. The challenge is to find innovative ways to include acoustics into core courses so that all students are exposed to the field and its applications. The design and analysis of machine elements such as cams, gears, etc. are always part of core courses. It is in these contexts that the acoustics through noise aspects including multimedia can be introduced. Acoustics as an effect due to vibration as cause can be included in vibration analysis. A core course on system modeling can include acoustics. The integration of acoustical topics not only strengthens the core courses but also prepares the graduating engineer to deal with real problems better. Thus, it is important for academic acousticians to bring acoustics into the core courses. This paper presents some efforts to include the acoustics material in some core courses.
3. 空调室外机气动与声学特性的研究进展%Advances in Investigation of Acoustic and Aerodynamic Noise in Air Conditioner Outdoor Unit
杨启容; 秦静静; 吴荣华; 王硕
2015-01-01
Noise in air conditioner outdoor unit includes mechanical noise,electromagnetic noise and aerodynamic noise.The effects of mechanic and electromagnetic noise are minor but aerodynamic noise effect is the key in the duct system of air condi-tioner outdoor unit.The history and u-to-date development of noise in air conditioner outdoor unit were reviewed,The detail analy-sis is carried out from three ways of methods of numerical modeling,experimental studies and modal analysis according to refer-ences.On the basis of the analysis and summary,the further needed work of noise reduction are put forward.%空调室外机噪声包括机械噪声、电磁噪声和气动噪声，其中机械噪声和电磁噪声在常规状态下影响较小，气动噪声是空调室外机风道系统的主要噪声。本文回顾了国内外关于空调室外机气动噪音的研究历史与现状，结合文献着重从数值模拟、试验研究以及模态分析几个方面进行了分析。经过分析总结，提出了进一步降噪需要开展的工作。
4. Traffic noise reduces foraging efficiency in wild owls
Senzaki, Masayuki; Yamaura, Yuichi; Francis, Clinton D.; Nakamura, Futoshi
2016-08-01
Anthropogenic noise has been increasing globally. Laboratory experiments suggest that noise disrupts foraging behavior across a range of species, but to reveal the full impacts of noise, we must examine the impacts of noise on foraging behavior among species in the wild. Owls are widespread nocturnal top predators and use prey rustling sounds for localizing prey when hunting. We conducted field experiments to examine the effect of traffic noise on owls’ ability to detect prey. Results suggest that foraging efficiency declines with increasing traffic noise levels due to acoustic masking and/or distraction and aversion to traffic noise. Moreover, we estimate that effects of traffic noise on owls’ ability to detect prey reach >120 m from a road, which is larger than the distance estimated from captive studies with bats. Our study provides the first evidence that noise reduces foraging efficiency in wild animals, and highlights the possible pervasive impacts of noise.
5. Aircraft noise prediction
Filippone, Antonio
2014-07-01
This contribution addresses the state-of-the-art in the field of aircraft noise prediction, simulation and minimisation. The point of view taken in this context is that of comprehensive models that couple the various aircraft systems with the acoustic sources, the propagation and the flight trajectories. After an exhaustive review of the present predictive technologies in the relevant fields (airframe, propulsion, propagation, aircraft operations, trajectory optimisation), the paper addresses items for further research and development. Examples are shown for several airplanes, including the Airbus A319-100 (CFM engines), the Bombardier Dash8-Q400 (PW150 engines, Dowty R408 propellers) and the Boeing B737-800 (CFM engines). Predictions are done with the flight mechanics code FLIGHT. The transfer function between flight mechanics and the noise prediction is discussed in some details, along with the numerical procedures for validation and verification. Some code-to-code comparisons are shown. It is contended that the field of aircraft noise prediction has not yet reached a sufficient level of maturity. In particular, some parametric effects cannot be investigated, issues of accuracy are not currently addressed, and validation standards are still lacking.
6. Extra-low-noise refrigerator with active noise control system, GR-W40NVI. Nodo seigyo choseiongata reizoko GR-W40NVI
Sekiguchi, Y.; Nakanishi, K.; Saruta, S. (Toshiba Corp., Tokyo (Japan))
1991-04-20
Aiming at lowering the noise down to a domestic background noise level, development was made of GR-W40NVI, extra-low-noise refrigerator with an active noise control system. The active control for lowering the noise is methodically to artificially generate sound, reverse in phase against the noise to be generated, silence it by acoustic wave interference, and theoretically reduce the acoustic pressure to zero. Such a technology was applied to the refrigerator morphologically as follows: In order to silence the noise, generated by the compressor and three-dimensionally diffused, by a simple structure, duct structure is applied for the noise to be diffused in one direction only, by acoustically insulating and confining the compressor with exception of its thermal exhaust opening. In order to lower the noise, generated by the compressor and amplified in zonal region, the active control is applied against the low frequency noise, while the conventional acoustic insulation/absorption technology is done against the high frequency noise. In order to quickly and accurately prepare sound, reverse in phase against the noise under fluctuation, signal processing is made by using digital signal processor (DSP), hardware exclusively for it. As a result, the noise was lowered by about 7dB (1/5) for the basic type of refrigerator. 12 figs.
7. Acoustic dose and acoustic dose-rate.
Duck, Francis
2009-10-01
Acoustic dose is defined as the energy deposited by absorption of an acoustic wave per unit mass of the medium supporting the wave. Expressions for acoustic dose and acoustic dose-rate are given for plane-wave conditions, including temporal and frequency dependencies of energy deposition. The relationship between the acoustic dose-rate and the resulting temperature increase is explored, as is the relationship between acoustic dose-rate and radiation force. Energy transfer from the wave to the medium by means of acoustic cavitation is considered, and an approach is proposed in principle that could allow cavitation to be included within the proposed definitions of acoustic dose and acoustic dose-rate.
8. Utilizing computer models for optimizing classroom acoustics
Hinckley, Jennifer M.; Rosenberg, Carl J.
2002-05-01
The acoustical conditions in a classroom play an integral role in establishing an ideal learning environment. Speech intelligibility is dependent on many factors, including speech loudness, room finishes, and background noise levels. The goal of this investigation was to use computer modeling techniques to study the effect of acoustical conditions on speech intelligibility in a classroom. This study focused on a simulated classroom which was generated using the CATT-acoustic computer modeling program. The computer was utilized as an analytical tool in an effort to optimize speech intelligibility in a typical classroom environment. The factors that were focused on were reverberation time, location of absorptive materials, and background noise levels. Speech intelligibility was measured with the Rapid Speech Transmission Index (RASTI) method.
9. 2nd International Symposium on Shipboard Acoustics
1986-01-01
The first International Symposium on Shipboard Acoustics, held in Noordwijkerhout (The Netherlands) in 1976, was a meeting of invited experts, each having considerable expertise in ship acoustics. Many of the participants were dealing with research on various ship acoustical subjects, and it proved to be a good idea to discuss future investigations and new techniques. At that time acousticians learned to use real-time signal-processing techniques and attempts were made to establish sound level prediction methods based on semi-fundamental considerations instead of the methods using empirically obtained data. Time was pressing as it was assumed that, in view of the adoption of Recommendation 141 of the International Labour Conference in 1970, authorities would soon make appropriate provisions to "protect seafarers from the ill effects of noise". This resulted in several national recommendations followed by the IMO "Code on noise levels aboard ships" which was adopted by the IMO Assembly in 1981. After that, pre...
10. Diagnostic techniques for measurement of aerodynamic noise in free field and reverberant environment of wind tunnels
El-Sum, H. M. A.; Mawardi, O. K.
1973-01-01
Techniques for studying aerodynamic noise generating mechanisms without disturbing the flow in a free field, and in the reverberation environment of the ARC wind tunnel were investigated along with the design and testing of an acoustic antenna with an electronic steering control. The acoustic characteristics of turbojet as a noise source, detection of direct sound from a source in a reverberant background, optical diagnostic methods, and the design characteristics of a high directivity acoustic antenna. Recommendations for further studies are included.
11. Underwater radiated noise from modern commercial ships.
McKenna, Megan F; Ross, Donald; Wiggins, Sean M; Hildebrand, John A
2012-01-01
Underwater radiated noise measurements for seven types of modern commercial ships during normal operating conditions are presented. Calibrated acoustic data (autonomous seafloor-mounted acoustic recorder were combined with ship passage information from the Automatic Identification System. This approach allowed for detailed measurements (i.e., source level, sound exposure level, and transmission range) on ships of opportunity. A key result was different acoustic levels and spectral shapes observed from different ship-types. A 54 kGT container ship had the highest broadband source level at 188 dB re 1 μPa@1m; a 26 kGT chemical tanker had the lowest at 177 dB re 1 μPa@1m. Bulk carriers had higher source levels near 100 Hz, while container ship and tanker noise was predominantly below 40 Hz. Simple models to predict source levels of modern merchant ships as a group from particular ship characteristics (e.g., length, gross tonnage, and speed) were not possible given individual ship-type differences. Furthermore, ship noise was observed to radiate asymmetrically. Stern aspect noise levels are 5 to 10 dB higher than bow aspect noise levels. Collectively, these results emphasize the importance of including modern ship-types in quantifying shipping noise for predictive models of global, regional, and local marine environments.
12. Jet engine noise and infrared plume correlation field campaign
Cunio, Phillip M.; Weber, Reed A.; Knobel, Kimberly R.; Smith, Christine; Draudt, Andy
2015-09-01
Jet engine noise can be a health hazard and environmental pollutant, particularly affecting personnel working in close proximity to jet engines, such as airline mechanics. Mitigating noise could reduce the potential for hearing loss in runway workers; however, there exists a very complex relationship between jet engine design parameters, operating conditions, and resultant noise power levels, and understanding and characterizing this relationship is a key step in mitigating jet engine noise effects. We demonstrate initial results highlighting the utility of high-speed imaging (hypertemporal imaging) in correlating the infrared signatures of jet engines with acoustic noise. This paper builds on prior theoretical analysis of jet engine infrared signatures and their potential relationships to jet engine acoustic emissions. This previous work identified the region of the jet plume most likely to emit both in infrared and in acoustic domains, and it prompted the investigation of wave packets as a physical construct tying together acoustic and infrared energy emissions. As a means of verifying these assertions, a field campaign to collect relevant data was proposed, and data collection was carried out with a bank of infrared instruments imaging a T700 turboshaft engine undergoing routine operational testing. The detection of hypertemporal signatures in association with acoustic signatures of jet engines enables the use of a new domain in characterizing jet engine noise. This may in turn enable new methods of predicting or mitigating jet engine noise, which could lead to socioeconomic benefits for airlines and other operators of large numbers of jet engines.
13. SIROCCO. Silent rotors by acoustic optimisation
Schepers, J.G.; Curvers, A. [ECN Wind Energy, Petten (Netherlands); Oerlemans, S. [National Aerospace Laboratory NLR, Amsterdam (Netherlands); Braun, K.; Lutz, T.; Herrig, A.; Wuerz, W. [University of Stuttgart, Stuttgart (Germany); Matesanz, A.; Garcillan, L. [Gamesa Eolica, Madrid (Spain); Fisher, M.; Koegler, K.; Maeder, T. [GE Wind Energy/GE Global Research (United States)
2007-07-15
In this paper the results from the European 5th Framework project 'SIROCCO' are described. The project started in January 2003 and will end in August 2007. The main aim of the SIROCCO project is to reduce wind-turbine aerodynamic noise significantly while maintaining the aerodynamic performance. This is achieved by designing new acoustically and aerodynamically optimised airfoils for the outer part of the blade. The project focussed primarily on reducing trailing edge noise, which was broadly believed to be the dominant noise mechanism of modern wind turbines.
14. Radiated noise of ducted fans
Eversman, Walter
The differences in the radiated acoustic fields of ducted and unducted propellers of the same thrust operating under similar conditions are investigated. An FEM model is created for the generation, propagation, and radiation of steady, rotor alone noise and exit guide vane interaction noise of a ducted fan. For a specified number of blades, angular mode harmonic, and rotor angular velocity, the acoustic field is described in a cylindrical coordinate system reduced to only the axial and radial directions. It is found that, contrary to the usual understanding of the Tyler and Sofrin (1962) result, supersonic tip speed rotor noise can be cut off if the tip Mach number is only slightly in excess of unity and if the number of blades is relatively small. If there are many blades, the fundamental angular mode number is large, and the Tyler and Sofrin result for thin annuli becomes more relevant. Shrouding of subsonic tip speed propellers is a very effective means of controlling rotor alone noise.
15. Design of sandwich acoustic window for sonar domes
YU Mengsa; LI Dongsheng; GONG Li; XU Jian
2005-01-01
Aimed at the low noise design of sonar dome in ships, a method has been presented for calculating the sonar self noise of a simplified sonar dome consisting of sandwich acoustic window and parallel acoustic cavity, which is excited by stationary random pressure fluctuation of turbulence boundary layer, using temporal and spatial double Fourier transform and wavenumber-frequency spectrum analysis. After numerically analyzing the influence of geometrical and physical parameters of acoustic window on the sonar self noise, the design method and reasonable parameters for sandwich acoustic window are proposed. The results show that the property of low noise induced by acoustic window of sandwich is dominated by the cut-off effect of longitudinal wave and transverse wave propagating in the visco-elastic layer of sandwich as well as the mismatch effect of impedance. If the thickness, density, Young's modulus and damping factor of plates and visco-elastic layer as well as the sound speed of longitudinal wave and transverse wave in the visco-elastic layer are selected reasonably, the maximum noise reduction of sandwich acoustic window is 6.5 dB greater than that of a single glass fiber reinforced plastic plate.
16. Underwater noise levels in UK waters
Merchant, Nathan D.; Brookes, Kate L.; Faulkner, Rebecca C.; Bicknell, Anthony W. J.; Godley, Brendan J.; Witt, Matthew J.
2016-11-01
Underwater noise from human activities appears to be rising, with ramifications for acoustically sensitive marine organisms and the functioning of marine ecosystems. Policymakers are beginning to address the risk of ecological impact, but are constrained by a lack of data on current and historic noise levels. Here, we present the first nationally coordinated effort to quantify underwater noise levels, in support of UK policy objectives under the EU Marine Strategy Framework Directive (MSFD). Field measurements were made during 2013-2014 at twelve sites around the UK. Median noise levels ranged from 81.5-95.5 dB re 1 μPa for one-third octave bands from 63-500 Hz. Noise exposure varied considerably, with little anthropogenic influence at the Celtic Sea site, to several North Sea sites with persistent vessel noise. Comparison of acoustic metrics found that the RMS level (conventionally used to represent the mean) was highly skewed by outliers, exceeding the 97th percentile at some frequencies. We conclude that environmental indicators of anthropogenic noise should instead use percentiles, to ensure statistical robustness. Power analysis indicated that at least three decades of continuous monitoring would be required to detect trends of similar magnitude to historic rises in noise levels observed in the Northeast Pacific.
17. Ares I Scale Model Acoustic Test Above Deck Water Sound Suppression Results
Counter, Douglas D.; Houston, Janice D.
2011-01-01
The Ares I Scale Model Acoustic Test (ASMAT) program test matrix was designed to determine the acoustic reduction for the Liftoff acoustics (LOA) environment with an above deck water sound suppression system. The scale model test can be used to quantify the effectiveness of the water suppression system as well as optimize the systems necessary for the LOA noise reduction. Several water flow rates were tested to determine which rate provides the greatest acoustic reductions. Preliminary results are presented.
18. Sonification of acoustic emission data
Raith, Manuel; Große, Christian
2014-05-01
While loading different specimens, acoustic emissions appear due to micro crack formation or friction of already existing crack edges. These acoustic emissions can be recorded using suitable ultrasonic transducers and transient recorders. The analysis of acoustic emissions can be used to investigate the mechanical behavior of different specimens under load. Our working group has undertaken several experiments, monitored with acoustic emission techniques. Different materials such as natural stone, concrete, wood, steel, carbon composites and bone were investigated. Also the experimental setup has been varied. Fire-spalling experiments on ultrahigh performance concrete and pullout experiments on bonded anchors have been carried out. Furthermore uniaxial compression tests on natural stone and animal bone had been conducted. The analysis tools include not only the counting of events but the analysis of full waveforms. Powerful localization algorithms and automatic onset picking techniques (based on Akaikes Information Criterion) were established to handle the huge amount of data. Up to several thousand events were recorded during experiments of a few minutes. More sophisticated techniques like moment tensor inversion have been established on this relatively small scale as well. Problems are related to the amount of data but also to signal-to-noise quality, boundary conditions (reflections) sensor characteristics and unknown and changing Greens functions of the media. Some of the acoustic emissions recorded during these experiments had been transferred into audio range. The transformation into the audio range was done using Matlab. It is the aim of the sonification to establish a tool that is on one hand able to help controlling the experiment in-situ and probably adjust the load parameters according to the number and intensity of the acoustic emissions. On the other hand sonification can help to improve the understanding of acoustic emission techniques for training
19. Noise Pollution
20. Distribution of Acoustic Power Spectra for an Isolated Helicopter Fuselage
Kusyumov A.N.
2016-01-01
Full Text Available The broadband aerodynamic noise can be studied, assuming isotropic flow, turbulence and decay. Proudman’s approach allows practical calculations of noise based on CFD solutions of RANS or URANS equations at the stage of post processing and analysis of the solution. Another aspect is the broadband acoustic spectrum and the distribution of acoustic power over a range of frequencies. The acoustic energy spectrum distribution in isotropic turbulence is non monotonic and has a maximum at a certain value of Strouhal number. In the present work the value of acoustic power peak frequency is determined using a prescribed form of acoustic energy spectrum distribution presented in papers by S. Sarkar and M. Y. Hussaini and by G. M. Lilley. CFD modelling of the flow around isolated helicopter fuselage model was considered using the HMB CFD code and the RANS equations.
1. Modern methods in analytical acoustics lecture notes
Crighton, D G; Williams, J E Ffowcs; Heckl, M; Leppington, F G
1992-01-01
Modern Methods in Analytical Acoustics considers topics fundamental to the understanding of noise, vibration and fluid mechanisms. The series of lectures on which this material is based began by some twenty five years ago and has been developed and expanded ever since. Acknowledged experts in the field have given this course many times in Europe and the USA. Although the scope of the course has widened considerably, the primary aim of teaching analytical techniques of acoustics alongside specific areas of wave motion and unsteady fluid mechanisms remains. The distinguished authors of this volume are drawn from Departments of Acoustics, Engineering of Applied Mathematics in Berlin, Cambridge and London. Their intention is to reach a wider audience of all those concerned with acoustic analysis than has been able to attend the course.
2. Acoustic Power Transmission Through a Ducted Fan
Envia, Ed
2016-01-01
For high-speed ducted fans, when the rotor flowfield is shock-free, the main contribution to the inlet radiated acoustic power comes from the portion of the rotor stator interaction sound field that is transmitted upstream through the rotor. As such, inclusion of the acoustic transmission is an essential ingredient in the prediction of the fan inlet noise when the fan tip relative speed is subsonic. This paper describes a linearized Euler based approach to computing the acoustic transmission of fan tones through the rotor. The approach is embodied in a code called LINFLUX was applied to a candidate subsonic fan called the Advanced Ducted Propulsor (ADP). The results from this study suggest that it is possible to make such prediction with sufficient fidelity to provide an indication of the acoustic transmission trends with the fan tip speed.
3. Numerical investigation of tandem-cylinder aerodynamic noise and its control with application to airframe noise
Eltaweel, Ahmed
Prediction and reduction of airframe noise are critically important to the development of quieter civil transport aircraft. The key to noise reduction is a full understanding of the underlying noise source mechanisms. In this study, tandem cylinders in cross-flow as an idealization of a complex aircraft landing gear configuration are considered to investigate the noise generation and its reduction by flow control using single dielectric barrier discharge plasma actuators. The flow over tandem cylinders at ReD = 22, 000 with and without plasma actuation is computed using large-eddy simulation. The plasma effect is modeled as a body force obtained from a semi-empirical model. The flow statistics and surface pressure frequency spectra show excellent agreement with previous experimental measurements. For acoustic calculations, a boundary-element method is implemented to solve the convected Lighthill equation. The solution method is validated in a number of benchmark problems including flows over a cylinder, a rod-airfoil configuration, and a sphere. With validated flow field and acoustic solver, acoustic analysis is performed for the tandem-cylinder configuration to extend the experimental results and understand the mechanisms of noise generation and its control. Without flow control, the acoustic field is dominated by the interaction between the downstream cylinder and the upstream wake. Through suppression of vortex shedding from the upstream cylinder, the interaction noise is reduced drastically by the plasma flow control, and the vortex-shedding noise from the downstream cylinder becomes equally important. At a free-stream Mach number of 0.2, the peak sound pressure level is reduced by approximately 16 dB. This suggests the viability of plasma actuation for active control of airframe noise. The numerical investigation is extended to the noise from a realistic landing gear experimental model. Coarse-mesh computations are performed, and preliminary results are
4. Jet Noise Diagnostics Supporting Statistical Noise Prediction Methods
Bridges, James E.
2006-01-01
The primary focus of my presentation is the development of the jet noise prediction code JeNo with most examples coming from the experimental work that drove the theoretical development and validation. JeNo is a statistical jet noise prediction code, based upon the Lilley acoustic analogy. Our approach uses time-average 2-D or 3-D mean and turbulent statistics of the flow as input. The output is source distributions and spectral directivity. NASA has been investing in development of statistical jet noise prediction tools because these seem to fit the middle ground that allows enough flexibility and fidelity for jet noise source diagnostics while having reasonable computational requirements. These tools rely on Reynolds-averaged Navier-Stokes (RANS) computational fluid dynamics (CFD) solutions as input for computing far-field spectral directivity using an acoustic analogy. There are many ways acoustic analogies can be created, each with a series of assumptions and models, many often taken unknowingly. And the resulting prediction can be easily reverse-engineered by altering the models contained within. However, only an approach which is mathematically sound, with assumptions validated and modeled quantities checked against direct measurement will give consistently correct answers. Many quantities are modeled in acoustic analogies precisely because they have been impossible to measure or calculate, making this requirement a difficult task. The NASA team has spent considerable effort identifying all the assumptions and models used to take the Navier-Stokes equations to the point of a statistical calculation via an acoustic analogy very similar to that proposed by Lilley. Assumptions have been identified and experiments have been developed to test these assumptions. In some cases this has resulted in assumptions being changed. Beginning with the CFD used as input to the acoustic analogy, models for turbulence closure used in RANS CFD codes have been explored and
5. Noise Evaluation Technique Based on Surface Pressure
Fischer, Andreas
2012-01-01
In this chapter the relevant theory for the understanding of TE noise modeling is collected. It contains the acoustic formulations of [31] and [57]. Both give a relation for the far field sound pressure in dependence of the frequency wave number spectral density of the pressure on the airfoil sur...
6. LOW-NOISE PAVEMENT AS A WAY OF LIMITATION OF TRAFFIC NOISE LEVEL
2014-11-01
Full Text Available Road surface can significantlyreduce the trafficnoise level. Depending on the characteristic of the upper surface layers the differences between the maximum rolling noise levels from passing vehicles to reach values about 10 dB (A. A special group is low-noise pavements characterized by the presence of voids above 15%. Application the porous asphalt layers or asphalt mixture type BBTM affects a significantreduction the width of land surrounded the roads where permissible equivalent sound level is exceeded. Such solutions in some cases can replace acoustic barriers. Road pavements with a higher content of voids require proper maintenance because their acoustic performances are reduced during operation.
7. Numerical simulation of generalized Langevin equation with arbitrary correlated noise.
Lü, Kun; Bao, Jing-Dong
2005-12-01
A generalized Langevin equation with arbitrary correlated noise and associated frequency-dependent friction is simulated, which can lead to anomalous diffusion. The algorithm is realized by using the Fourier transform technique to generate noise and the stochastic Runge-Kutta method to solve the whole equation. Application to an acoustic phonon model, initial preparation-dependent ballistic diffusion, is shown.
8. Status: Crewmember Noise Exposures on the International Space Station
Limardo-Rodriguez, Jose G.; Allen, Christopher S.; Danielson, Richard W.
2015-01-01
The International Space Station (ISS) provides a unique environment where crewmembers from the US and our international partners work and live for as long as 6 to 12 consecutive months. During these long-durations ISS missions, noise exposures from onboard equipment are posing concerns for human factors and crewmember health risks, such as possible reductions in hearing sensitivity, disruptions of crew sleep, interference with speech intelligibility and voice communications, interference with crew task performance, and reduced alarm audibility. It is crucial to control acoustical noise aboard ISS to acceptable noise exposure levels during the work-time period, and to also provide a restful sleep environment during the sleep-time period. Acoustic dosimeter measurements, obtained when the crewmember wears the dosimeter for 24-hour periods, are conducted onboard ISS every 60 days and compared to ISS flight rules. NASA personnel then assess the acoustic environment to which the crewmembers are exposed, and provide recommendations for hearing protection device usage. The purpose of this paper is to provide an update on the status of ISS noise exposure monitoring and hearing conservation strategies, as well as to summarize assessments of acoustic dosimeter data collected since the Increment 36 mission (April 2013). A description of the updated noise level constraints flight rule, as well as the Noise Exposure Estimation Tool and the Noise Hazard Inventory implementation for predicting crew noise exposures and recommending to ISS crewmembers when hearing protection devices are required, will be described.
9. Noise control for rapid transit cars on elevated structures
Hanson, C. E.
1983-03-01
Noise control treatments for the propulsion motor noise of rapid transit cars on concrete elevated structures and the noise reduction from barrier walls were investigated by using acoustical scale models and supplemented by field measurements of noise from trains operated by the Port Authority Transportation Corporation (PATCO) in New Jersey. The results show that vehicle skirts and undercar sound absorption can provide substantial cost-effective reductions in propulsion noise at the wayside of transit systems with concrete elevated guideways. The acoustical scale model noise reductions applied to PATCO vehicles on concrete elevated structures show reductions in the A-weighted noise levels of 5 dB for undercar sound absorption, 5 dB for vehicle skirts, and 10 dB for combined undercar absorption and vehicle skirts. Acoustical scale model results for sound barrier walls lined with absorptive treatment showed reductions from 7 dB to 12 dB of noise from vehicles in the far track, depending on the height of the wall, and reductions from 12 dB to 20 dB of noise from vehicles on the near track. Transit vehicles at high speeds where propulsion system noise dominates are 7 dB(A) noisier at 50 ft on concrete elevated structures than on at-grade on tie and ballast. Of this amount, 3 dB is due to loss of ground effect, and 4 dB is due to the absence of undercar absorption provided by ballast.
10. Magneto-acoustic imaging by continuous-wave excitation.
Shunqi, Zhang; Zhou, Xiaoqing; Tao, Yin; Zhipeng, Liu
2016-07-01
The electrical characteristics of tissue yield valuable information for early diagnosis of pathological changes. Magneto-acoustic imaging is a functional approach for imaging of electrical conductivity. This study proposes a continuous-wave magneto-acoustic imaging method. A kHz-range continuous signal with an amplitude range of several volts is used to excite the magneto-acoustic signal and improve the signal-to-noise ratio. The magneto-acoustic signal amplitude and phase are measured to locate the acoustic source via lock-in technology. An optimisation algorithm incorporating nonlinear equations is used to reconstruct the magneto-acoustic source distribution based on the measured amplitude and phase at various frequencies. Validation simulations and experiments were performed in pork samples. The experimental and simulation results agreed well. While the excitation current was reduced to 10 mA, the acoustic signal magnitude increased up to 10(-7) Pa. Experimental reconstruction of the pork tissue showed that the image resolution reached mm levels when the excitation signal was in the kHz range. The signal-to-noise ratio of the detected magneto-acoustic signal was improved by more than 25 dB at 5 kHz when compared to classical 1 MHz pulse excitation. The results reported here will aid further research into magneto-acoustic generation mechanisms and internal tissue conductivity imaging.
11. Mathematical modeling of complex noise barriers
Hayek, S.I.
1982-01-01
Mathematical modeling of the noise reduction efficiency of highway noise barriers depends on the shape and absorptivity of the barrier, the influence of the impedance of the ground under the receiver, the atmospheric conditions as well as traffic details. The mathematical model for a barrier's noise reduction requires the knowledge of point-to-point acoustic diffraction models. In many instances, the shape of the barrier is simple; such as thin wall (edge), sharp wedge, and cylindrically topped berms. However, new designs of more efficient barriers have been investigated recently.
12. Measurement of acoustical characteristics of mosques in Saudi Arabia
2003-03-01
The study of mosque acoustics, with regard to acoustical characteristics, sound quality for speech intelligibility, and other applicable acoustic criteria, has been largely neglected. In this study a background as to why mosques are designed as they are and how mosque design is influenced by worship considerations is given. In the study the acoustical characteristics of typically constructed contemporary mosques in Saudi Arabia have been investigated, employing a well-known impulse response. Extensive field measurements were taken in 21 representative mosques of different sizes and architectural features in order to characterize their acoustical quality and to identify the impact of air conditioning, ceiling fans, and sound reinforcement systems on their acoustics. Objective room-acoustic indicators such as reverberation time (RT) and clarity (C50) were measured. Background noise (BN) was assessed with and without the operation of air conditioning and fans. The speech transmission index (STI) was also evaluated with and without the operation of existing sound reinforcement systems. The existence of acoustical deficiencies was confirmed and quantified. The study, in addition to describing mosque acoustics, compares design goals to results obtained in practice and suggests acoustical target values for mosque design. The results show that acoustical quality in the investigated mosques deviates from optimum conditions when unoccupied, but is much better in the occupied condition.
13. Active noise control: A tutorial for HVAC designers
Gelin, L.J.
1997-08-01
This article will identify the capabilities and limitations of ANC in its application to HVAC noise control. ANC can be used in ducted HVAC systems to cancel ductborne, low-frequency fan noise by injecting sound waves of equal amplitude and opposite phase into an air duct, as close as possible to the source of the unwanted noise. Destructive interference of the fan noise and injected noise results in sound cancellation. The noise problems that it solves are typically described as rumble, roar or throb, all of which are difficult to address using traditional noise control methods. This article will also contrast the use of active against passive noise control techniques. The main differences between the two noise control measures are acoustic performance, energy consumption, and design flexibility. The article will first present the fundamentals and basic physics of ANC. The application to real HVAC systems will follow.
14. Theoretical investigation of noise transmission into a finite cylinder
Li, Deyu; Vipperman, Jeffrey S.
2004-05-01
A new mathematical model for characterizing noise transmission into a finite elastic cylindrical structure with application to a ChamberCore composite cylinder is presented. A plane wave obliquely impinges on the structure, the external sound field is approximated by the solution for an infinite cylinder, and the internal sound field is solved with the structural and acoustic modal interaction method. The noise reduction spectrum for characterizing noise transmission into the cylinder is defined, and the analytical model for the calculation of the noise reduction spectrum is developed. The analytical results show that the cavity resonances dominate the noise transmission into the finite cylinder, and the longitudinal acoustic modes play an important role in the noise transmission at the low frequencies. These results are matched with experimental results.
15. Spacecraft Internal Acoustic Environment Modeling
Chu, SShao-sheng R.; Allen, Christopher S.
2009-01-01
Acoustic modeling can be used to identify key noise sources, determine/analyze sub-allocated requirements, keep track of the accumulation of minor noise sources, and to predict vehicle noise levels at various stages in vehicle development, first with estimates of noise sources, later with experimental data. In FY09, the physical mockup developed in FY08, with interior geometric shape similar to Orion CM (Crew Module) IML (Interior Mode Line), was used to validate SEA (Statistical Energy Analysis) acoustic model development with realistic ventilation fan sources. The sound power levels of these sources were unknown a priori, as opposed to previous studies that RSS (Reference Sound Source) with known sound power level was used. The modeling results were evaluated based on comparisons to measurements of sound pressure levels over a wide frequency range, including the frequency range where SEA gives good results. Sound intensity measurement was performed over a rectangular-shaped grid system enclosing the ventilation fan source. Sound intensities were measured at the top, front, back, right, and left surfaces of the and system. Sound intensity at the bottom surface was not measured, but sound blocking material was placed tinder the bottom surface to reflect most of the incident sound energy back to the remaining measured surfaces. Integrating measured sound intensities over measured surfaces renders estimated sound power of the source. The reverberation time T6o of the mockup interior had been modified to match reverberation levels of ISS US Lab interior for speech frequency bands, i.e., 0.5k, 1k, 2k, 4 kHz, by attaching appropriately sized Thinsulate sound absorption material to the interior wall of the mockup. Sound absorption of Thinsulate was modeled in three methods: Sabine equation with measured mockup interior reverberation time T60, layup model based on past impedance tube testing, and layup model plus air absorption correction. The evaluation/validation was
16. Prediction for Outlet Noise of Rolling Piston Comperssor
Zhang Tieshan
2015-01-01
Full Text Available An acoustic wave equation with considering small perturbation is presented first by use of the fluidic mechanics and aerodynamics, then a theoretical model for predicting the outlet noise of rolling piston compressors is investigated, and the sound pressure and sound power of the outlet noise are formulated based on the acoustic wave equation. The experimental data and simulation results for the outlet noise with different rotation velocities have been compared with the discrepancy less than 2.6%, which verifies the approach presented in this paper.
17. Prediction of speech masking release for fluctuating interferers based on the envelope power signal-to-noise ratio
Jørgensen, Søren; Dau, Torsten
2012-01-01
segments. Predictions obtained with the short-term sEPSM are compared to data from Kjems et al. [(2009). J. Acoust. Soc. Am. 126 (3), 1415-1426] where speech is mixed with four different interferers, including speech-shaped noise, bottle noise, car noise, and a highly non-stationary cafe noise. The model...
18. Prediction of speech masking release for fluctuating interferers based on the envelope power signal-to-noise ratio
Jørgensen, Søren; Dau, Torsten
2012-01-01
EPSM are compared to data from Kjems et al. [(2009). J. Acoust. Soc. Am. 126 (3), 1415-1426] where speech is mixed with four different interferers, including speech-shaped noise, bottle noise, car noise, and a highly non-stationary cafe noise. The model accounts well for the differences in intelligibility observed...
19. Wind Turbines: Unsteady Aerodynamics and Inflow Noise
Broe, Brian Riget
; and Graham, J. M. R.: 1970, Lifting surface theory for the problem of an arbitrarily yawed sinusoidal gust incident on a thin aerofoil in incompressible flow). Two of these models are investigated to find the unsteady lift distribution or pressure difference as function of chordwise position on the aerofoil...... (Sears, W. R.: 1941; and Graham, J. M. R.: 1970). An acoustic model is investigated using a model for the lift distribution as input (Amiet, R. K.: 1975, Acoustic radiation from an airfoil in a turbulent stream). The two models for lift distribution are used in the acoustic model. One of the models...... and the perfectly isotropic turbulent model. This indicates that the models capture the aerodynamics well. Thus the measurements suggest that the noise due to atmospheric turbulence can be described and modeled by the two models for lift distribution. It was not possible to test the acoustical model...
20. Supersonic Jet Noise Reduction Using Microjets
Gutmark, Ephraim; Cuppoletti, Dan; Malla, Bhupatindra
2013-11-01
Fluidic injection for jet noise reduction involves injecting secondary jets into a primary jet to alter the noise characteristics of the primary jet. A major challenge has been determining what mechanisms are responsible for noise reduction due to varying injector designs, injection parameters, and primary jets. The current study provides conclusive results on the effect of injector angle and momentum ux ratio on the acoustics and shock structure of a supersonic Md = 1.56 jet. It is shown that the turbulent mixing noise scales primarily with the injector momentum flux ratio. Increasing the injector momentum flux ratio increases streamwise vorticity generation and reduces peak turbulence levels. It is found that the shock-related noise components are most affected by the interaction of the shocks from the injectors with the primary shock structure of the jet. Increasing momentum flux ratio causes shock noise reduction until a limit where shock noise increases again. It is shown that the shock noise components and mixing noise components are reduced through fundamentally different mechanisms and maximum overall noise reduction is achieved by balancing the reduction of both components.
1. Acoustic Issues in Human Spaceflight
Clark, Jonathan B.
2001-01-01
NASA is concerned about acute effect of sound on crew performance on International Space Station (ISS), and is developing strategies to assess and reduce acute, chronic, and delayed effects of sound. High noise levels can cause headaches, irritation, fatigue, impaired sleep, headache, and tinnitus and have resulted in an inability to hear alarms. Speech intelligibility may be more impaired for crew understanding non-native language in a noisy environment. No hearing loss occurred, but significant effects on crew performance and communication occurred. Permanent Threshold Shifts (PTS) have not been observed in the US shuttle program. Russian specification for noise in spacecraft is 60 dBA (awake) and 50 dBA (asleep) while the U.S. noise specification on ISS is NC 50 (awake) and NC 40 (asleep) with a 85 dBA hazard limit. Background noise levels of ISS modules have measured 56-69 dBA. Treadmill exercise operations measure 77 dBA. Alarms are required to be 20 dBA above ambient. Hearing protection is recommended when noise exceeds 60 dB 24 hour Leq. Countermeasures include hearing protection and design/ engineering controls. Advanced composite materials with excellent low frequency attenuation properties could be applied as a barrier protection around noisy equipment, or used on personal protective equipment worn by the crew. Hearing protection countermeasures include foam ear inserts, passive muff headsets, and active noise reduction headsets. Oto-acoustic emissions (OAE) could be used to monitor effectiveness of hearing protection countermeasures and tailor hearing protection countermeasures to individual crewmembers. Micro-gravity, vibration, toxic fumes, air quality/composition, stress, temperature, physical exertion or some combination of the above factors may have interacted with moderate long-term noise exposure to cause significant hearing loss. Longitudinal studies will need to address what co-morbidity factors, such as radiation, toxicology, microgravity
2. Sensitive acoustic vibration sensor using single-mode fiber tapers.
Li, Yi; Wang, Xiaozhen; Bao, Xiaoyi
2011-05-01
Optical fiber sensors are a good alternative to piezoelectric devices in electromagnetic sensitive environments. In this study, we reported a fiber acoustic sensor based on single-mode fiber (SMF) tapers. The fiber taper is used as the sensing arm in a Mach-Zehnder interferometer. Benefiting from their micrometer dimensions, fiber tapers have shown higher sensitivities to the acoustic vibrations than SMFs. Under the same conditions, the thinnest fiber taper in this report, with a diameter of 1.7 µm, shows a 20 dB improvement in the signal to noise ratio as compared to that of an SMF. This acoustic vibration sensor can detect the acoustic waves over the frequencies of 30 Hz-40 kHz, which is limited by the acoustic wave generator in experiments. We also discussed the phase changes of fiber tapers with different diameters under acoustic vibrations.
3. Mechanisms of active control for noise inside a vibrating cylinder
Lester, Harold C.; Fuller, Chris R.
1987-01-01
The active control of propeller-induced noise fields inside a flexible cylinder is studied with attention given to the noise reduction mechanisms inherent in the present coupled acoustic shell model. The active noise control model consists of an infinitely long aluminum cylinder with a radius of 0.4 m and a thickness of 0.001 m. Pressure maps are shown when the two external sources are driven in-phase at a frequency corresponding to Omega = 0.22.
4. NASA's Aeroacoustic Tools and Methods for Analysis of Aircraft Noise
Rizzi, Stephen A.; Lopes, Leonard V.; Burley, Casey L.
2015-01-01
Aircraft community noise is a significant concern due to continued growth in air traffic, increasingly stringent environmental goals, and operational limitations imposed by airport authorities. The ability to quantify aircraft noise at the source and ultimately at observers is required to develop low noise aircraft designs and flight procedures. Predicting noise at the source, accounting for scattering and propagation through the atmosphere to the observer, and assessing the perception and impact on a community requires physics-based aeroacoustics tools. Along with the analyses for aero-performance, weights and fuel burn, these tools can provide the acoustic component for aircraft MDAO (Multidisciplinary Design Analysis and Optimization). Over the last decade significant progress has been made in advancing the aeroacoustic tools such that acoustic analyses can now be performed during the design process. One major and enabling advance has been the development of the system noise framework known as Aircraft NOise Prediction Program2 (ANOPP2). ANOPP2 is NASA's aeroacoustic toolset and is designed to facilitate the combination of acoustic approaches of varying fidelity for the analysis of noise from conventional and unconventional aircraft. The toolset includes a framework that integrates noise prediction and propagation methods into a unified system for use within general aircraft analysis software. This includes acoustic analyses, signal processing and interfaces that allow for the assessment of perception of noise on a community. ANOPP2's capability to incorporate medium fidelity shielding predictions and wind tunnel experiments into a design environment is presented. An assessment of noise from a conventional and Hybrid Wing Body (HWB) aircraft using medium fidelity scattering methods combined with noise measurements from a model-scale HWB recently placed in NASA's 14x22 wind tunnel are presented. The results are in the form of community noise metrics and
5. Extracting Coherent Information from Noise Based Correlation Processing
2015-09-30
LONG-TERM GOALS The goal of this research is to establish methodologies to utilize ambient noise in the ocean and to determine what scenarios...None PUBLICATIONS [1] “ Monitoring deep-ocean temperatures using acoustic ambinet noise,”K. W. Woolfe, S. Lani, K.G. Sabra, W. A. Kuperman...Geophys. Res. Lett., 42,2878–2884, doi:10.1002/2015GL063438 (2015). [2] “Optimized extraction of coherent arrivals from ambient noise correlations in
6. Using VAPEPS for noise control on Space Station Freedom
Badilla, Gloria; Bergen, Thomas; Scharton, Terry
1991-01-01
Noise environmental control is an important design consideration for Space Station Freedom (SSF), both for crew safety and productivity. Acoustic noise requirements are established to eliminate fatigue and potential hearing loss by crew members from long-term exposure and to facilitate speech communication. VAPEPS (VibroAcoustic Payload Environment Prediction System) is currently being applied to SSF for prediction of the on-orbit noise and vibration environments induced in the 50 to 10,000 Hz frequency range. Various sources such as fans, pumps, centrifuges, exercise equipment, and other mechanical devices are used in the analysis. The predictions will be used in design tradeoff studies and to provide confidence that requirements will be met. Preliminary predictions show that the required levels will be exceeded unless substantial noise control measures are incorporated in the SSF design. Predicted levels for an SSF design without acoustic control treatments exceed requirements by 25 dB in some one-third octave frequency bands.
7. Tuned Chamber Core Panel Acoustic Test Results
Schiller, Noah H.; Allen, Albert R.
2016-01-01
This report documents acoustic testing of tuned chamber core panels, which can be used to supplement the low-frequency performance of conventional acoustic treatment. The tuned chamber core concept incorporates low-frequency noise control directly within the primary structure and is applicable to sandwich constructions with a directional core, including corrugated-, truss-, and fluted-core designs. These types of sandwich structures have long, hollow channels (or chambers) in the core. By adding small holes through one of the facesheets, the hollow chambers can be utilized as an array of low-frequency acoustic resonators. These resonators can then be used to attenuate low-frequency noise (below 400 Hz) inside a vehicle compartment without increasing the weight or size of the structure. The results of this test program demonstrate that the tuned chamber core concept is effective when used in isolation or combined with acoustic foam treatments. Specifically, an array of acoustic resonators integrated within the core of the panels was shown to improve both the low-frequency absorption and transmission loss of the structure in targeted one-third octave bands.
8. Background studies for acoustic neutrino detection at the South Pole
Abbasi, R; Abu-Zayyad, T; Adams, J; Aguilar, J A; Ahlers, M; Andeen, K; Auffenberg, J; Bai, X; Baker, M; Barwick, S W; Bay, R; Alba, J L Bazo; Beattie, K; Beatty, J J; Bechet, S; Becker, J K; Becker, K -H; Benabderrahmane, M L; BenZvi, S; Berdrmann, J; Berghaus, P; Berley, D; Bernardini, E; Bertrand, D; Besson, D Z; Bindig, D; Bissok, M; Blaufuss, E; Blumenthal, J; Boersma, D J; Bohm, C; Bose, D; Böser, S; Botner, O; Braun, J; Brown, A M; Buitink, S; Carson, M; Chirkin, D; Christy, B; Clem, J; Clevermann, F; Cohen, S; Colnard, C; Cowen, D F; D'Agostino, M V; Danninger, M; Daughhetee, J; Davis, J C; De Clercq, C; Demirörs, L; Denger, T; Depaepe, O; Descamps, F; Desiati, P; de Vries-Uiterweerd, G; DeYoung, T; Diaz-Vélez, J C; Dierckxsens, M; Dreyer, J; Dumm, J P; Ehrlich, R; Eisch, J; Ellsworth, R W; Engdegård, O; Euler, S; Evenson, P A; Fadiran, O; Fazely, A R; Fedynitch, A; Feusels, T; Filimonov, K; Finley, C; Fischer-Wasels, T; Foerster, M M; Fox, B D; Franckowiak, A; Franke, R; Gaisser, T K; Gallagher, J; Geisler, M; Gerhardt, L; Gladstone, L; Glüsenkamp, T; Goldschmidt, A; Goodman, J A; Grant, D; Griesel, T; Groß, A; Grullon, S; Gurtner, M; Ha, C; Hallgren, A; Halzen, F; Han, K; Hanson, K; Heinen, D; Helbing, K; Herquet, P; Hickford, S; Hill, G C; Hoffman, K D; Homeier, A; Hoshina, K; Hubert, D; Huelsnitz, W; Hülß, J -P; Hulth, P O; Hultqvist, K; Hussain, S; Ishihara, A; Jacobsen, J; Japaridze, G S; Johansson, H; Joseph, J M; Kampert, K -H; Kappes, A; Karg, T; Karle, A; Kelley, J L; Kenny, P; Kiryluk, J; Kislat, F; Klein, S R; Köhne, J -H; Kohnen, G; Kolanoski, H; Köpke, L; Kopper, S; Koskinen, D J; Kowalski, M; Kowarik, T; Krasberg, M; Krings, T; Kroll, G; Kuehn, K; Kuwabara, T; Labare, M; Lafebre, S; Laihem, K; Landsman, H; Larson, M J; Lauer, R; Lünemann, J; Madsen, J; Majumdar, P; Marotta, A; Maruyama, R; Mase, K; Matis, H S; Meagher, K; Merck, M; Mészáros, P; Meures, T; Middell, E; Milke, N; Miller, J; Montaruli, T; Morse, R; Movit, S M; Nahnhauer, R; Nam, J W; Naumann, U; Nießen, P; Nygren, D R; Odrowski, S; Olivas, A; Olivo, M; O'Murchadha, A; Ono, M; Panknin, S; Paul, L; Heros, C Pérez de los; Petrovic, J; Piegsa, A; Pieloth, D; Porrata, R; Posselt, J; Price, P B; Prikockis, M; Przybylski, G T; Rawlins, K; Redl, P; Resconi, E; Rhode, W; Ribordy, M; Rizzo, A; Rodrigues, J P; Roth, P; Rothmaier, F; Rott, C; Ruhe, T; Rutledge, D; Ruzybayev, B; Ryckbosch, D; Sander, H -G; Santander, M; Sarkar, S; Schatto, K; Schmidt, T; Schönwald, A; Schukraft, A; Schultes, A; Schulz, O; Schunck, M; Seckel, D; Semburg, B; Seo, S H; Sestayo, Y; Seunarine, S; Silvestri, A; Slipak, A; Spiczak, G M; Spiering, C; Stamatikos, M; Stanev, T; Stephens, G; Stezelberger, T; Stokstad, R G; Stössl, A; Stoyanov, S; Strahler, E A; Straszheim, T; Stür, M; Sullivan, G W; Swillens, Q; Taavola, H; Taboada, I; Tamburro, A; Tepe, A; Ter-Antonyan, S; Tilav, S; Toale, P A; Toscano, S; Tosi, D; Turčan, D; van Eijndhoven, N; Vandenbroucke, J; Van Overloop, A; van Santen, J; Vehring, M; Voge, M; Walck, C; Waldenmaier, T; Wallraff, M; Walter, M; Weaver, Ch; Wendt, C; Westerhoff, S; Whitehorn, N; Wiebe, K; Wiebusch, C H; Williams, D R; Wischnewski, R; Wissing, H; Wolf, M; Woschnagg, K; Xu, C; Xu, X W; Yodh, G; Yoshida, S; Zarzhitsky, P
2011-01-01
The detection of acoustic signals from ultra-high energy neutrino interactions is a promising method to measure the tiny flux of cosmogenic neutrinos expected on Earth. The energy threshold for this process depends strongly on the absolute noise level in the target material. The South Pole Acoustic Test Setup (SPATS), deployed in the upper part of four boreholes of the IceCube Neutrino Observatory, has monitored the noise in Antarctic ice at the geographic South Pole for more than two years down to 500 m depth. The noise is very stable and Gaussian distributed. Lacking an in-situ calibration up to now, laboratory measurements have been used to estimate the absolute noise level in the 10 to 50 kHz frequency range to be smaller than 20 mPa. Using a threshold trigger, sensors of the South Pole Acoustic Test Setup registered acoustic pulse-like events in the IceCube detector volume and its vicinity. Acoustic signals from refreezing IceCube holes and from anthropogenic sources have been used to localize acoustic e...
9. Use of acoustic vortices in acoustic levitation
Cutanda Henriquez, Vicente; Santillan, Arturo Orozco; Juhl, Peter Møller
2009-01-01
Acoustic fields are known to exert forces on the surfaces of objects. These forces are noticeable if the sound pressure is sufficiently high. Two phenomena where acoustic forces are relevant are: i) acoustic levitation, where strong standing waves can hold small objects at certain positions......, counterbalancing their weight, and ii) acoustic vortices, spinning sound fields that can impinge angular momentum and cause rotation of objects. In this contribution, both force-creating sound fields are studied by means of numerical simulations. The Boundary Element Method is employed to this end. The simulation...... of acoustical vortices uses an efficient numerical implementation based on the superposition of two orthogonal sound fields with a delay of 90° between them. It is shown that acoustic levitation and the use of acoustic vortices can be combined to manipulate objects in an efficient and controlled manner without...
10. Acoustic cryocooler
Swift, Gregory W.; Martin, Richard A.; Radenbaugh, Ray
1990-01-01
An acoustic cryocooler with no moving parts is formed from a thermoacoustic driver (TAD) driving a pulse tube refrigerator (PTR) through a standing wave tube. Thermoacoustic elements in the TAD are spaced apart a distance effective to accommodate the increased thermal penetration length arising from the relatively low TAD operating frequency in the range of 15-60 Hz. At these low operating frequencies, a long tube is required to support the standing wave. The tube may be coiled to reduce the overall length of the cryocooler. One or two PTR's are located on the standing wave tube adjacent antinodes in the standing wave to be driven by the standing wave pressure oscillations. It is predicted that a heat input of 1000 W at 1000 K will maintian a cooling load of 5 W at 80 K.
11. Experiments and simulations of flow noise inside a cylinder aligned with the flow
Elboth, Thomas; Andreassen, Øyvind; Reif, Bjørn Anders
2008-11-01
This work uses Lighthill's acoustic analogy to investigate noise generated by a turbulent boundary layer surrounding a cylinder aligned with the flow direction. Based on a DNS of channel flow with a Reynolds number Reτ=180, both the direct and the acoustic pressure fluctuations (self-noise) from the turbulent boundary layer surrounding the cylinder are computed. The computational domain is surrounded by a Perfectly Matched Layer (PML) absorbing boundary conditions. The result from the simulation is compared with noise data recorded on a purpose built experimental seismic streamer towed in the ocean. We do this to gain knowledge about how turbulent flow noise in a towed'' cylinder behaves and to compare the turbulent flow noise with other sources of noise found in towed sonar arrays, commonly used for maritime surveillance and geophysical exploration. Based on both simulations and measurements we present spectral estimates of the acoustic field and estimates of the spatial coherence distance'' of the noise.
12. Large refinery and petrochemical plant furnaces and heaters : low frequency noise measurement and noise source order-ranking
Leslie Frank, HFP Acoustical Consultants Corp. Calgary AB
2007-07-01
Large furnaces and process heaters at refineries, gas plants, and petrochemical plants produce a low-frequency tonal noise from combustion roar. They can also produce mid-frequency broadband noise from induced draft fans. The common noise generating mechanisms are turbulence, flow instability, pressure drop, mechanical friction, and component vibration. Some of these energy facilities have multiple furnaces and heaters. As such, a noise source order-ranking assessment is typically performed to determine which plant equipment is responsible for the highest sound level contributions at nearby residence locations. The order-ranking is useful in determining which noise sources may require acoustical treatment to reduce the overall sound level at each residence. These results would form the basis for evaluating the effect of noise mitigating strategies for each source, and for estimating the associated costs for each noise control scenario. The noise model results can also be used to order-rank the equipment noise sources in terms of their frequency-dependant octave band. Experience has shown that large furnaces and heaters usually rank very high in terms of predominant contributors. The combustion roar noise generating mechanism is largely responsible for the predominant amount of acoustical energy. Although some degree of noise reduction can be achieved through burner design, it was shown that noise control engineering largely occurs at the furnace and heater manufacturing or plant retrofit level. This paper presented the results of one refinery with 19 older style furnaces and heaters. 1 tab., 7 figs.
13. Acoustic telemetry.
Drumheller, Douglas Schaeffer; Kuszmaul, Scott S.
2003-08-01
Broadcasting messages through the earth is a daunting task. Indeed, broadcasting a normal telephone conversion through the earth by wireless means is impossible with todays technology. Most of us don't care, but some do. Industries that drill into the earth need wireless communication to broadcast navigation parameters. This allows them to steer their drill bits. They also need information about the natural formation that they are drilling. Measurements of parameters such as pressure, temperature, and gamma radiation levels can tell them if they have found a valuable resource such as a geothermal reservoir or a stratum bearing natural gas. Wireless communication methods are available to the drilling industry. Information is broadcast via either pressure waves in the drilling fluid or electromagnetic waves in the earth and well tubing. Data transmission can only travel one way at rates around a few baud. Given that normal Internet telephone modems operate near 20,000 baud, these data rates are truly very slow. Moreover, communication is often interrupted or permanently blocked by drilling conditions or natural formation properties. Here we describe a tool that communicates with stress waves traveling through the steel drill pipe and production tubing in the well. It's based on an old idea called Acoustic Telemetry. But what we present here is more than an idea. This tool exists, it's drilled several wells, and it works. Currently, it's the first and only acoustic telemetry tool that can withstand the drilling environment. It broadcasts one way over a limited range at much faster rates than existing methods, but we also know how build a system that can communicate both up and down wells of indefinite length.
14. A study of the prediction of cruise noise and laminar flow control noise criteria for subsonic air transports
Swift, G.; Mungur, P.
1979-01-01
General procedures for the prediction of component noise levels incident upon airframe surfaces during cruise are developed. Contributing noise sources are those associated with the propulsion system, the airframe and the laminar flow control (LFC) system. Transformation procedures from the best prediction base of each noise source to the transonic cruise condition are established. Two approaches to LFC/acoustic criteria are developed. The first is a semi-empirical extension of the X-21 LFC/acoustic criteria to include sensitivity to the spectrum and directionality of the sound field. In the second, the more fundamental problem of how sound excites boundary layer disturbances is analyzed by deriving and solving an inhomogeneous Orr-Sommerfeld equation in which the source terms are proportional to the production and dissipation of sound induced fluctuating vorticity. Numerical solutions are obtained and compared with corresponding measurements. Recommendations are made to improve and validate both the cruise noise prediction methods and the LFC/acoustic criteria.
15. Numerical modeling of wind turbine aerodynamic noise in the time domain.
Lee, Seunghoon; Lee, Seungmin; Lee, Soogab
2013-02-01
Aerodynamic noise from a wind turbine is numerically modeled in the time domain. An analytic trailing edge noise model is used to determine the unsteady pressure on the blade surface. The far-field noise due to the unsteady pressure is calculated using the acoustic analogy theory. By using a strip theory approach, the two-dimensional noise model is applied to rotating wind turbine blades. The numerical results indicate that, although the operating and atmospheric conditions are identical, the acoustical characteristics of wind turbine noise can be quite different with respect to the distance and direction from the wind turbine.
16. Core Noise Diagnostics of Turbofan Engine Noise Using Correlation and Coherence Functions
Miles, Jeffrey H.
2009-01-01
Cross-correlation and coherence functions are used to look for periodic acoustic components in turbofan engine combustor time histories, to investigate direct and indirect combustion noise source separation based on signal propagation time delays, and to provide information on combustor acoustics. Using the cross-correlation function, time delays were identified in all cases, clearly indicating the combustor is the source of the noise. In addition, unfiltered and low-pass filtered at 400 Hz signals had a cross-correlation time delay near 90 ms, while the low-pass filtered at less than 400 Hz signals had a cross-correlation time delay longer than 90 ms. Low-pass filtering at frequencies less than 400 Hz partially removes the direct combustion noise signals. The remainder includes the indirect combustion noise signal, which travels more slowly because of the dependence on the entropy convection velocity in the combustor. Source separation of direct and indirect combustion noise is demonstrated by proper use of low-pass filters with the cross-correlation function for a range of operating conditions. The results may lead to a better idea about the acoustics in the combustor and may help develop and validate improved reduced-order physics-based methods for predicting direct and indirect combustion noise.
17. 高速铁路声屏障几何形状声学性能数值模拟%Numerical Study on Acoustic Performance of High-speed Railway Noise Barriers with Different Geometric Shape
何宾; 肖新标; 周信; 温泽峰; 金学松
2016-01-01
为了弄清声屏障几何形状对高速铁路户外噪声的降噪机理和降噪效果，采用二维边界元法建立高架桥铁路声屏障噪声预测模型，分析不同几何形状结构参数对降噪性能的影响。分析中考虑列车运行速度、声源分布及频谱特性对插入损失的影响，根据车外声源识别结果建立符合我国高速铁路的声源模型；考虑车体-轨道-声屏障之间的多重反射，建立边界元计算模型；对顶部倾斜、T型、多重绕射边型、Y型、圆柱型等声屏障的结构参数的影响进行调查分析，分析中分别考虑插入损失、场点频谱及声场变化规律。研究结果表明，Y型声屏障降噪效果最好，平均插入损失提高3.4 dB(A)其次为圆柱型声屏障。%The geometrical shapes of sound barriers have an effect on high-speed railway external noise. In order to make clear the noise reduction mechanism and effect of the sound barrier with different geometric head shape, the two-dimension(2D) boundary element method(BEM) is used to develop a noise prediction model for railway noise barrier. Using the model,the structure parameters of the different sound barriers are investigated and their noise reduction performance is analyzed. With taking into account the influence of train speed, sound sources distribution and their frequency characteristics on insertion loss(IL), the sound source model of high-speed railway is developed according to the external noise source identification results. A BEM calculation model is developed on through sufficient considering the multiple reflections among train body, track and sound barrier. The noise reduction effects of sound barriers with sloping top, T-shaped top, multiple diffraction edges, Y-shaped top and cylinder-shaped top are surveyed. In the discussion, the changes of IL, frequency spectrum of field points and sound field are given. It’s shown that the noise reduction effect of Y-shaped sound barrier
18. Reduction of diesel engine exhaust noise in the petroleum mining industry. [by resonator type diffuser
Marinov, T.
1974-01-01
An important noise source in a drilling plant is Diesel engine exhaust. In order to reduce this noise, a reactive silencer of the derivative resonator type was proposed, calculated from the acoustic and design point of view and applied. As a result of applying such a silencer on the exhaust conduit of a Diesel engine the noise level dropped down to 18 db.
19. Reconstruction methods for acoustic particle detection in the deep sea using clusters of hydrophones
Richardt, C; Graf, K; Hoessl, J; Kappes, A; Katz, U; Lahmann, R; Naumann, Ch; Neff, M; Schoeck, F; 10.1016/j.astropartphys.2008.11.003
2009-01-01
This article focuses on techniques for acoustic noise reduction, signal filters and source reconstruction. For noise reduction, bandpass filters and cross correlations are found to be efficient and fast ways to improve the signal to noise ratio and identify a possible neutrino-induced acoustic signal. The reconstruction of the position of an acoustic point source in the sea is performed by using small-volume clusters of hydrophones (about 1 cubic meter) for direction reconstruction by a beamforming algorithm. The directional information from a number of such clusters allows for position reconstruction. The algorithms for data filtering, direction and position reconstruction are explained and demonstrated using simulated data.
20. Acoustics of friction.
2002-04-01
This article presents an overview of the acoustics of friction by covering friction sounds, friction-induced vibrations and waves in solids, and descriptions of other frictional phenomena related to acoustics. Friction, resulting from the sliding contact of solids, often gives rise to diverse forms of waves and oscillations within solids which frequently lead to radiation of sound to the surrounding media. Among the many everyday examples of friction sounds, violin music and brake noise in automobiles represent the two extremes in terms of the sounds they produce and the mechanisms by which they are generated. Of the multiple examples of friction sounds in nature, insect sounds are prominent. Friction also provides a means by which energy dissipation takes place at the interface of solids. Friction damping that develops between surfaces, such as joints and connections, in some cases requires only microscopic motion to dissipate energy. Modeling of friction-induced vibrations and friction damping in mechanical systems requires an accurate description of friction for which only approximations exist. While many of the components that contribute to friction can be modeled, computational requirements become prohibitive for their contemporaneous calculation. Furthermore, quantification of friction at the atomic scale still remains elusive. At the atomic scale, friction becomes a mechanism that converts the kinetic energy associated with the relative motion of surfaces to thermal energy. However, the description of the conversion to thermal energy represented by a disordered state of oscillations of atoms in a solid is still not well understood. At the macroscopic level, friction interacts with the vibrations and waves that it causes. Such interaction sets up a feedback between the friction force and waves at the surfaces, thereby making friction and surface motion interdependent. Such interdependence forms the basis for friction-induced motion as in the case of
1. Parameter Optimization Analysis of the Secondary Acoustic Sources for Power Transformer Active Noise Control%电力变压器有源降噪中次级声源的参数优化分析
王学磊; 张黎; 李庆民; 娄杰; 孙晓阳
2012-01-01
为了获得较好的全局有源降噪效果,需合理布置次级声源,次级声源参数优化是电力变压器有源降噪技术研究中的核心问题。在分析有源降噪物理机制的基础上,建立了电力变压器的噪声辐射模型,得到变压器周围声场分布与噪声源、次级声源的关系。考虑实际工程需要,将次级声源参数分为2大类,并结合噪声辐射模型,从数目、位置、源强3方面对次级声源进行参数优化。鉴于位置和源强等参数间的交互影响关系,提出对固定参数和灵活参数进行交替优选,形成基于遗传算法的渐次搜索逼近策略。通过将具体算例与基于COMSOL软件的仿真结果相比较,表明该优化策略可获得较好的全局有源降噪效果。%In order to obtain a preferable global active noise reduction,thd most important thing is the reasonable arrangement of secondary source,so parameters optimization of the secondary sources is the principal issue for active noise control technology of power transformers.On the basis of the physical mechanism of active noise reduction,we established a noise radiation model for power transformers,and obtained the relationship between the sound field distribution around the transformer and the sound source including noise source and the secondary sources.With consideration of practical requirements and by combining with the noise radiation model,key parameters of the secondary sources were divided into two categories so as to realize parameter optimization in terms of source number,location,and strength.For interactive impacts resulted from secondary source location and strength,a scheme to alternately optimize the fixed parameters and the flexible parameters was proposed,and thereby agradual search approximation strategy based on genetic algorithm was further put forward.Case studies are compared with the simulation results by COMSOL software,showing that,with the proposed optimization strategy
2. Coupled vibro-acoustic model updating using frequency response functions
Nehete, D. V.; Modak, S. V.; Gupta, K.
2016-03-01
Interior noise in cavities of motorized vehicles is of increasing significance due to the lightweight design of these structures. Accurate coupled vibro-acoustic FE models of such cavities are required so as to allow a reliable design and analysis. It is, however, experienced that the vibro-acoustic predictions using these models do not often correlate acceptably well with the experimental measurements and hence require model updating. Both the structural and the acoustic parameters addressing the stiffness as well as the damping modeling inaccuracies need to be considered simultaneously in the model updating framework in order to obtain an accurate estimate of these parameters. It is also noted that the acoustic absorption properties are generally frequency dependent. This makes use of modal data based methods for updating vibro-acoustic FE models difficult. In view of this, the present paper proposes a method based on vibro-acoustic frequency response functions that allow updating of a coupled FE model by considering simultaneously the parameters associated with both the structural as well as the acoustic model of the cavity. The effectiveness of the proposed method is demonstrated through numerical studies on a 3D rectangular box cavity with a flexible plate. Updating parameters related to the material property, stiffness of joints between the plate and the rectangular cavity and the properties of absorbing surfaces of the acoustic cavity are considered. The robustness of the method under presence of noise is also studied.
3. Generation of indirect combustion noise by compositional inhomogeneities
Magri, Luca; O'Brien, Jeff; Ihme, Matthias
2016-11-01
The generation of indirect combustion noise in nozzles and turbine stages is commonly attributed to temperature inhomogeneities and vorticity fluctuations. Here, compositional inhomogeneities in a multi-component gas mixture are shown to produce indirect noise both theoretically and numerically. The chemical potential function is introduced as an additional acoustic source mechanism. The contribution of the compositional noise is compared to the entropy noise and direct noise by considering subsonic, supersonic and shocked nozzles downstream of the combustor exit. It is shown that the compositional noise is dependent on the local mixture composition and can exceed entropy noise for fuel-lean conditions and supersonic/shocked nozzle flows. This suggests that compositional indirect combustion noise may require consideration with the implementation of advanced combustion concepts in gas turbines, including low-emissions combustors, high-power-density engine cores, or compact burners.
4. Study on noise prediction model and control schemes for substation.
Chen, Chuanmin; Gao, Yang; Liu, Songtao
2014-01-01
With the government's emphasis on environmental issues of power transmission and transformation project, noise pollution has become a prominent problem now. The noise from the working transformer, reactor, and other electrical equipment in the substation will bring negative effect to the ambient environment. This paper focuses on using acoustic software for the simulation and calculation method to control substation noise. According to the characteristics of the substation noise and the techniques of noise reduction, a substation's acoustic field model was established with the SoundPLAN software to predict the scope of substation noise. On this basis, 4 reasonable noise control schemes were advanced to provide some helpful references for noise control during the new substation's design and construction process. And the feasibility and application effect of these control schemes can be verified by using the method of simulation modeling. The simulation results show that the substation always has the problem of excessive noise at boundary under the conventional measures. The excess noise can be efficiently reduced by taking the corresponding noise reduction methods.
5. A Comprehensive Approach to Management of Workplace and Environmental Noise at NASA Lewis Research Center
Cooper, Beth A.
1995-01-01
NASA Lewis Research Center is home to more than 100 experimental research testing facilities and laboratories, including large wind tunnels and engine test cells, which in combination create a varied and complex noise environment. Much of the equipment was manufactured prior to the enactment of legislation limiting product noise emissions or occupational noise exposure. Routine facility maintenance and associated construction also contributes to a noise exposure management responsibility which is equal in magnitude and scope to that of several small industrial companies. The Noise Program, centrally managed within the Office of Environmental Programs at LRC, maintains overall responsibility for hearing conservation, community noise control, and acoustical and noise control engineering. Centralized management of the LRC Noise Program facilitates the timely development and implementation of engineered noise control solutions for problems identified via either the Hearing Conservation of Community Noise Program. The key element of the Lewis Research Center Noise Program, Acoustical and Noise Control Engineering Services, is focused on developing solutions that permanently reduce employee and community noise exposure and maximize research productivity by reducing or eliminating administrative and operational controls and by improving the safety and comfort of the work environment. The Hearing Conservation Program provides noise exposure assessment, medical monitoring, and training for civil servant and contractor employees. The Community Noise Program aims to maintain the support of LRC's neighboring communities while enabling necessary research operations to accomplish their programmatic goals. Noise control engineering capability resides within the Noise Program. The noise control engineering, based on specific exposure limits, is a fundamental consideration throughout the design phase of new test facilities, labs, and office buildings. In summary, the Noise Program
6. Responsive acoustic surfaces
Peters, Brady; Tamke, Martin; Nielsen, Stig Anton;
2011-01-01
Acoustic performance is defined by the parameter of reverberation time; however, this does not capture the acoustic experience in some types of open plan spaces. As many working and learning activities now take place in open plan spaces, it is important to be able to understand and design...... for the acoustic conditions of these spaces. This paper describes an experimental research project that studied the design processes necessary to design for sound. A responsive acoustic surface was designed, fabricated and tested. This acoustic surface was designed to create specific sonic effects. The design...... was simulated using custom integrated acoustic software and also using Odeon acoustic analysis software. The research demonstrates a method for designing space- and sound-defining surfaces, defines the concept of acoustic subspace, and suggests some new parameters for defining acoustic subspaces....
7. Noise reduction of spiral ducts.
Lapka, Wojciech; Cempel, Czesław
2007-01-01
The paper presents noise reduction (NR) of spiral ducts as a result of computational modeling of acoustic wave propagation. Three-dimensional models were created with the finite element method in COMSOL Multiphysics version 3.3. Nine models of spiral ducts with 1-9 spiral leads were considered. Time-harmonic analysis was used to predict NR, which was shown in spectral and interval frequency bands. Spiral duct performance can be seen as a comparison of NR before and after a change from a circular to a spiral duct.
8. Acoustic Green's function extraction in the ocean
Zang, Xiaoqin
The acoustic Green's function (GF) is the key to understanding the acoustic properties of ocean environments. With knowledge of the acoustic GF, the physics of sound propagation, such as dispersion, can be analyzed; underwater communication over thousands of miles can be understood; physical properties of the ocean, including ocean temperature, ocean current speed, as well as seafloor bathymetry, can be investigated. Experimental methods of acoustic GF extraction can be categorized as active methods and passive methods. Active methods are based on employment of man-made sound sources. These active methods require less computational complexity and time, but may cause harm to marine mammals. Passive methods cost much less and do not harm marine mammals, but require more theoretical and computational work. Both methods have advantages and disadvantages that should be carefully tailored to fit the need of each specific environment and application. In this dissertation, we study one passive method, the noise interferometry method, and one active method, the inverse filter processing method, to achieve acoustic GF extraction in the ocean. The passive method of noise interferometry makes use of ambient noise to extract an approximation to the acoustic GF. In an environment with a diffusive distribution of sound sources, sound waves that pass through two hydrophones at two locations carry the information of the acoustic GF between these two locations; by listening to the long-term ambient noise signals and cross-correlating the noise data recorded at two locations, the acoustic GF emerges from the noise cross-correlation function (NCF); a coherent stack of many realizations of NCFs yields a good approximation to the acoustic GF between these two locations, with all the deterministic structures clearly exhibited in the waveform. To test the performance of noise interferometry in different types of ocean environments, two field experiments were performed and ambient noise
9. Depolarized guided acoustic wave Brillouin scattering in hollow-core photonic crystal fibers
Zhong, Wenjia Elser née; Elser, Dominique; Heim, Bettina; Marquardt, Christoph; Leuchs, Gerd
2015-01-01
By performing quantum-noise-limited optical heterodyne detection, we observe polarization noise in light after propagation through a hollow-core photonic crystal fiber (PCF). We compare the noise spectrum to the one of a standard fiber and find an increase of noise even though the light is mainly transmitted in air in a hollow-core PCF. Combined with our simulation of the acoustic vibrational modes in the hollow-core PCF, we are offering an explanation for the polarization noise with a variation of guided acoustic wave Brillouin scattering (GAWBS). Here, instead of modulating the strain in the fiber core as in a solid core fiber, the acoustic vibrations in hollow-core PCF influence the effective refractive index by modulating the geometry of the photonic crystal structure. This induces polarization noise in the light guided by the photonic crystal structure.
10. Acoustic topological insulator and robust one-way sound transport
He, Cheng; Ni, Xu; Ge, Hao; Sun, Xiao-Chen; Chen, Yan-Bin; Lu, Ming-Hui; Liu, Xiao-Ping; Chen, Yan-Feng
2016-12-01
Topological design of materials enables topological symmetries and facilitates unique backscattering-immune wave transport. In airborne acoustics, however, the intrinsic longitudinal nature of sound polarization makes the use of the conventional spin-orbital interaction mechanism impossible for achieving band inversion. The topological gauge flux is then typically introduced with a moving background in theoretical models. Its practical implementation is a serious challenge, though, due to inherent dynamic instabilities and noise. Here we realize the inversion of acoustic energy bands at a double Dirac cone and provide an experimental demonstration of an acoustic topological insulator. By manipulating the hopping interaction of neighbouring ’atoms’ in this new topological material, we successfully demonstrate the acoustic quantum spin Hall effect, characterized by robust pseudospin-dependent one-way edge sound transport. Our results are promising for the exploration of new routes for experimentally studying topological phenomena and related applications, for example, sound-noise reduction.
11. Acoustic Spatiality
Brandon LaBelle
2012-06-01
Full Text Available Experiences of listening can be appreciated as intensely relational, bringing us into contact with surrounding events, bodies and things. Given that sound propagates and expands outwardly, as a set of oscillations from a particular source, listening carries with it a sensual intensity, whereby auditory phenomena deliver intrusive and disruptive as well as soothing and assuring experiences. The physicality characteristic of sound suggests a deeply impressionistic, locational "knowledge structure" – that is, the ways in which listening affords processes of exchange, of being in the world, and from which we extend ourselves. Sound, as physical energy reflecting and absorbing into the materiality around us, and even one's self, provides a rich platform for understanding place and emplacement. Sound is always already a trace of location.Such features of auditory experience give suggestion for what I may call an acoustical paradigm – how sound sets in motion not only the material world but also the flows of the imagination, lending to forces of signification and social structure, and figuring us in relation to each other. The relationality of sound brings us into a steady web of interferences, each of which announces the promise or problematic of being somewhere.
12. Acoustic Neurinomas
2011-01-01
Full Text Available Acoustic neuromas (AN are schwann cell-derived tumors that commonly arise from the vestibular portion of the eighth cranial nerve also known as vestibular schwannoma(VS causes unilateral hearing loss, tinnitus, vertigo and unsteadiness. In many cases, the tumor size may remain unchanged for many years following diagnosis, which is typically made by MRI. In the majority of cases the tumor is small, leaving the clinician and patient with the options of either serial scanning or active treatment by gamma knife radiosurgery (GKR or microneurosurgery. Despite the vast number of published treatment reports, comparative studies are few. The predominant clinical endpoints of AN treatment include tumor control, facial nerve function and hearing preservation. Less focus has been put on symptom relief and health-related quality of life (QOL. It is uncertain if treating a small tumor leaves the patient with a better chance of obtaining relief from future hearing loss, vertigo or tinnitus than by observing it without treatment. In this paper we review the literature for the natural course, the treatment alternatives and the results of AN. Finally, we present our experience with a management strategy applied for more than 30 years.
13. Aerodynamic Noise Prediction Using stochastic Turbulence Modeling
2008-01-01
Full Text Available Amongst many approaches to determine the sound propagated from turbulent flows, hybrid methods, in which the turbulent noise source field is computed or modeled separately from the far field calculation, are frequently used. For basic estimation of sound propagation, less computationally intensive methods can be developed using stochastic models of the turbulent fluctuations (turbulent noise source field. A simple and easy to use stochastic model for generating turbulent velocity fluctuations called continuous filter white noise (CFWN model was used. This method based on the use of classical Langevian-equation to model the details of fluctuating field superimposed on averaged computed quantities. The resulting sound field due to the generated unsteady flow field was evaluated using Lighthill's acoustic analogy. Volume integral method used for evaluating the acoustic analogy. This formulation presents an advantage, as it confers the possibility to determine separately the contribution of the different integral terms and also integration regions to the radiated acoustic pressure. Our results validated by comparing the directivity and the overall sound pressure level (OSPL magnitudes with the available experimental results. Numerical results showed reasonable agreement with the experiments, both in maximum directivity and magnitude of the OSPL. This method presents a very suitable tool for the noise calculation of different engineering problems in early stages of the design process where rough estimates using cheaper methods are needed for different geometries.
14. Identification of the noise using mathematical modelling
Dobeš, Josef; Kozubková, Milada; Mahdal, Miroslav
2016-03-01
In engineering applications the noisiness of a component or the whole device is a common problem. Currently, a lot of effort is put to eliminate noise of the already produced devices, to prevent generation of acoustic waves during the design of new components, or to specify the operating problems based on noisiness change. The experimental method and the mathematical modelling method belong to these identification methods. With the power of today's computers the ability to identify the sources of the noise on the mathematical modelling level is a very appreciated tool for engineers. For example, the noise itself may be generated by the vibration of the solid object, combustion, shock, fluid flow around an object or cavitation at the fluid flow in an object. For the given task generating the noise using fluid flow on the selected geometry and propagation of the acoustic waves and their subsequent identification are solved and evaluated. In this paper the principle of measurement of variables describing the fluid flow field and acoustic field are described. For the solution of fluid flow a mathematical model implemented into the CFD code is used. The mathematical modelling evaluation of the flow field is compared to the experimental data.
15. A Hybrid Approach To Tandem Cylinder Noise
Lockard, David P.
2004-01-01
Aeolian tone generation from tandem cylinders is predicted using a hybrid approach. A standard computational fluid dynamics (CFD) code is used to compute the unsteady flow around the cylinders, and the acoustics are calculated using the acoustic analogy. The CFD code is nominally second order in space and time and includes several turbulence models, but the SST k - omega model is used for most of the calculations. Significant variation is observed between laminar and turbulent cases, and with changes in the turbulence model. A two-dimensional implementation of the Ffowcs Williams-Hawkings (FW-H) equation is used to predict the far-field noise.
16. Acoustic source for generating an acoustic beam
Vu, Cung Khac; Sinha, Dipen N.; Pantea, Cristian
2016-05-31
An acoustic source for generating an acoustic beam includes a housing; a plurality of spaced apart piezo-electric layers disposed within the housing; and a non-linear medium filling between the plurality of layers. Each of the plurality of piezoelectric layers is configured to generate an acoustic wave. The non-linear medium and the plurality of piezo-electric material layers have a matching impedance so as to enhance a transmission of the acoustic wave generated by each of plurality of layers through the remaining plurality of layers.
17. Canonical Acoustics and Its Application to Surface Acoustic Wave on Acoustic Metamaterials
Shen, Jian Qi
2016-08-01
In a conventional formalism of acoustics, acoustic pressure p and velocity field u are used for characterizing acoustic waves propagating inside elastic/acoustic materials. We shall treat some fundamental problems relevant to acoustic wave propagation alternatively by using canonical acoustics (a more concise and compact formalism of acoustic dynamics), in which an acoustic scalar potential and an acoustic vector potential (Φ ,V), instead of the conventional acoustic field quantities such as acoustic pressure and velocity field (p,u) for characterizing acoustic waves, have been defined as the fundamental variables. The canonical formalism of the acoustic energy-momentum tensor is derived in terms of the acoustic potentials. Both the acoustic Hamiltonian density and the acoustic Lagrangian density have been defined, and based on this formulation, the acoustic wave quantization in a fluid is also developed. Such a formalism of acoustic potentials is employed to the problem of negative-mass-density assisted surface acoustic wave that is a highly localized surface bound state (an eigenstate of the acoustic wave equations). Since such a surface acoustic wave can be strongly confined to an interface between an acoustic metamaterial (e.g., fluid-solid composite structures with a negative dynamical mass density) and an ordinary material (with a positive mass density), it will give rise to an effect of acoustic field enhancement on the acoustic interface, and would have potential applications in acoustic device design for acoustic wave control.
18. Sodium boiling detection in LMFBRs by acoustic-neutronic cross correlation
Wright, S.A.
1977-01-01
The acoustic and neutronic noise signals caused by boiling are the signals primarily considered likely to detect sodium boiling in an LMFBR. Unfortunately, these signals may have serious signal-to-noise problems due to strong background noise sources. Neutronic-acoustic cross correlation techniques are expected to provide a means of improving the signal-to-noise ratio. This technique can improve the signal-to-noise ratio because the neutronic and acoustic signals due to boiling are highly correlated near the bubble repetition frequency, while the background noise sources are expected to be uncorrelated (or at most weakly correlated). An experiment was designed to show that the neutronic and acoustic noise signals are indeed highly correlated. The experiment consisted of simulating the void and pressure effects of local sodium boiling in the core of a zero-power reactor (ARK). The analysis showed that the neutronic and acoustic noise signals caused by boiling are almost perfectly correlated in a wide frequency band about the bubble repetition frequency. The results of the experiments were generalized to full-scale reactors to compare the inherent effectiveness of the methods which use the neutronic or acoustic signals alone with a hybrid method, which cross correlates the neutronic and acoustic signals. It was concluded that over a zone of the reactor where the void coefficient is sufficiently large (approximately 85 percent the core volume), the cross correlation method can provide a more rapid detection system for a given signal-to-noise ratio. However, where the void coefficient is small, one must probably rely on the acoustic method alone.
19. On Noise Assessment for Blended Wing Body Aircraft
Guo, Yueping; Burley, Casey L; Thomas, Russell H.
2014-01-01
A system noise study is presented for the blended-wing-body (BWB) aircraft configured with advanced technologies that are projected to be available in the 2025 timeframe of the NASA N+2 definition. This system noise assessment shows that the noise levels of the baseline configuration, measured by the cumulative Effective Perceived Noise Level (EPNL), have a large margin of 34 dB to the aircraft noise regulation of Stage 4. This confirms the acoustic benefits of the BWB shielding of engine noise, as well as other projected noise reduction technologies, but the noise margins are less than previously published assessments and are short of meeting the NASA N+2 noise goal. In establishing the relevance of the acoustic assessment framework, the design of the BWB configuration, the technical approach of the noise analysis, the databases and prediction tools used in the assessment are first described and discussed. The predicted noise levels and the component decomposition are then analyzed to identify the ranking order of importance of various noise components, revealing the prominence of airframe noise, which holds up the levels at all three noise certification locations and renders engine noise reduction technologies less effective. When projected airframe component noise reduction is added to the HWB configuration, it is shown that the cumulative noise margin to Stage 4 can reach 41.6 dB, nearly at the NASA goal. These results are compared with a previous NASA assessment with a different study framework. The approaches that yield projections of such low noise levels are discussed including aggressive assumptions on future technologies, assumptions on flight profile management, engine installation, and component noise reduction technologies. It is shown that reliable predictions of component noise also play an important role in the system noise assessment. The comparisons and discussions illustrate the importance of practical feasibilities and constraints in aircraft
20. An Acoustic Echo Cancellation System based on Adaptive Algorithm
2012-01-01
Adaptive filtering technique is one of the core technologies in digital signal processing and finds numerous application areas in science as well as in industry. Adaptive filtering technique is widely used in many applications, including echo cancellation, adaptive noise cancellation, adaptive beam forming and adaptive equalization. Acoustic echo is a common occurrence in today’s telecommunication systems. The distraction caused by the acoustic echo, reduces the speech quality in the communic...
1. Acoustic array systems theory, implementation, and application
Bai, Mingsian R; Benesty, Jacob
2013-01-01
Presents a unified framework of far-field and near-field array techniques for noise source identification and sound field visualization, from theory to application. Acoustic Array Systems: Theory, Implementation, and Application provides an overview of microphone array technology with applications in noise source identification and sound field visualization. In the comprehensive treatment of microphone arrays, the topics covered include an introduction to the theory, far-field and near-field array signal processing algorithms, practical implementations, and common applic
2. Study of acoustic signal in the process of resistance spot welding based on array sensor system
2008-01-01
This investigation was performed to study acoustic field signal in order to improve RSW quality. Researchers firstly built an acoustic array sensor system, which included 8 MPA-416 acoustic sensors, data acquisition card and LabVIEW. The system obtained the acoustic field information in the process of nugget growing. Due to the nonlinearity field signal, array sensor algorithm was utilized to quantitatively analyze the characteristics of acoustic field and reduced noise. The experiment and calculation results show that array sensor system can acquire acoustic field signal of nugget growing in the RSW process and array processing algorithm based on acoustic field can extract characteristic parameters to evaluate RSW quality. It was concluded that the acoustic array sensor system offers a new methodology for RSW quality inspection.
3. Fan Noise Source Diagnostic Test Computation of Rotor Wake Turbulence Noise
Nallasamy, M.; Envia, E.; Thorp, S. A.; Shabbir, A.
2002-01-01
An important source mechanism of fan broadband noise is the interaction of rotor wake turbulence with the fan outlet guide vanes. A broadband noise model that utilizes computed rotor flow turbulence from a RANS code is used to predict fan broadband noise spectra. The noise model is employed to examine the broadband noise characteristics of the 22-inch Source Diagnostic Test fan rig for which broadband noise data were obtained in wind tunnel tests at the NASA Glenn Research Center. A 9-case matrix of three outlet guide vane configurations at three representative fan tip speeds are considered. For all cases inlet and exhaust acoustic power spectra are computed and compared with the measured spectra where possible. In general, the acoustic power levels and shape of the predicted spectra are in good agreement with the measured data. The predicted spectra show the experimentally observed trends with fan tip speed, vane count, and vane sweep. The results also demonstrate the validity of using CFD-based turbulence information for fan broadband noise calculations.
4. Effects of Bifurcations on Aft-Fan Engine Nacelle Noise
Nark, Douglas M.; Farassat, Fereidoun; Pope, D. Stuart; Vatsa, Veer N.
2004-01-01
Aft-fan engine nacelle noise is a significant factor in the increasingly important issue of aircraft community noise. The ability to predict such noise within complex duct geometries is a valuable tool in studying possible noise attenuation methods. A recent example of code development for such predictions is the ducted fan noise propagation and radiation code CDUCT-LaRC. This work focuses on predicting the effects of geometry changes (i.e. bifurcations, pylons) on aft fan noise propagation. Beginning with simplified geometries, calculations show that bifurcations lead to scattering of acoustic energy into higher order modes. In addition, when circumferential mode number and the number of bifurcations are properly commensurate, bifurcations increase the relative importance of the plane wave mode near the exhaust plane of the bypass duct. This is particularly evident when the bypass duct surfaces include acoustic treatment. Calculations involving more complex geometries further illustrate that bifurcations and pylons clearly affect modal content, in both propagation and radiation calculations. Additionally, results show that consideration of acoustic radiation results may provide further insight into acoustic treatment effectiveness for situations in which modal decomposition may not be straightforward. The ability of CDUCT-LaRC to handle complex (non-axisymmetric) multi-block geometries, as well as axially and circumferentially segmented liners, allows investigation into the effects of geometric elements (bifurcations, pylons).
Bolčina, Matjaž
2014-01-01
Noise is everywhere. Noise is a sound that makes people stressful and irritate. It often couses sleep disorders and also health problems like different cardiovascular disorders, hearing loss…In most cases traffic noise is the most disturbing. There are different ways to prevent people from traffic noise like building noise barriers and insulation of facades. However noise barriers and insulation of facades do not prevent noise formation, but are lowering existing noise. Another disadvantage i...
6. Aeroacoustic Calculations of Wind Turbine Noise with the Actuator Line/ Navier-Stokes Technique
Debertshäuser, Harald; Shen, Wen Zhong; Zhu, Wei Jun
2016-01-01
to the local conditions and airfoil data. In the acoustic solver, the aeroacoustics is simulated by: (1) calculating the noise source using the improved engineering model (IBPM) based on the model developed by Brook, Pope and Marcolini (BPM); (2) introducing the noise source with an expected range......Noise regulations in many countries are becoming extremely strict and wind turbine noise is thus becoming a barrier for further development of onshore wind turbines. Low noise wind turbine airfoil and blade design is an important technique for noise reduction. However, the ow situation of a wind...... technique where the wind turbine flow is calculated by using the in-house actuator line/LES/Navier-Stokes technique and the acoustics is obtained by solving the acoustic perturbation equations. In the flow solver, the wind turbine blades are modelled by rotating lines with body forces determined according...
7. A survey of acoustic conditions in semi-open plan classrooms in the United Kingdom.
Greenland, Emma E; Shield, Bridget M
2011-09-01
This paper reports the results of a large scale, detailed acoustic survey of 42 open plan classrooms of varying design in the UK each of which contained between 2 and 14 teaching areas or classbases. The objective survey procedure, which was designed specifically for use in open plan classrooms, is described. The acoustic measurements relating to speech intelligibility within a classbase, including ambient noise level, intrusive noise level, speech to noise ratio, speech transmission index, and reverberation time, are presented. The effects on speech intelligibility of critical physical design variables, such as the number of classbases within an open plan unit and the selection of acoustic finishes for control of reverberation, are examined. This analysis enables limitations of open plan classrooms to be discussed and acoustic design guidelines to be developed to ensure good listening conditions. The types of teaching activity to provide adequate acoustic conditions, plus the speech intelligibility requirements of younger children, are also discussed.
8. Covert underwater acoustic communications.
Ling, Jun; He, Hao; Li, Jian; Roberts, William; Stoica, Petre
2010-11-01
Low probability of detection (LPD) communications are conducted at a low received signal-to-noise ratio (SNR) to deter eavesdroppers to sense the presence of the transmitted signal. Successful detection at intended receiver heavily relies on the processing gain achieved by employing the direct-sequence spread-spectrum (DSSS) technique. For scenarios that lack a sufficiently low SNR to maintain LPD, another metric, referred to as low probability of interception (LPI), is of interest to protect the privacy of the transmitted information. If covert communications take place in underwater acoustic (UWA) environments, then additional challenges are present. The time-varying nature of the UWA channel prevents the employment of a long spreading waveform. Furthermore, UWA environments are frequency-selective channels with long memory, which imposes challenges to the design of the spreading waveform. In this paper, a covert UWA communication system that adopts the DSSS technique and a coherent RAKE receiver is investigated. Emphasis is placed on the design of a spreading waveform that not only accounts for the transceiver structure and frequency-selective nature of the UWA channel, but also possesses a superior LPI. The proposed techniques are evaluated using both simulated and SPACE'08 in-water experimental data.
9. Acoustic Signal Processing
Hartmann, William M.; Candy, James V.
Signal processing refers to the acquisition, storage, display, and generation of signals - also to the extraction of information from signals and the re-encoding of information. As such, signal processing in some form is an essential element in the practice of all aspects of acoustics. Signal processing algorithms enable acousticians to separate signals from noise, to perform automatic speech recognition, or to compress information for more efficient storage or transmission. Signal processing concepts are the building blocks used to construct models of speech and hearing. Now, in the 21st century, all signal processing is effectively digital signal processing. Widespread access to high-speed processing, massive memory, and inexpensive software make signal processing procedures of enormous sophistication and power available to anyone who wants to use them. Because advanced signal processing is now accessible to everybody, there is a need for primers that introduce basic mathematical concepts that underlie the digital algorithms. The present handbook chapter is intended to serve such a purpose.
10. Feedforward control of sound transmission using an active acoustic metamaterial
Cheer, Jordan; Daley, Stephen; McCormick, Cameron
2017-02-01
Metamaterials have received significant interest in recent years due to their potential ability to exhibit behaviour not found in naturally occurring materials. This includes the generation of band gaps, which are frequency regions with high levels of wave attenuation. In the context of acoustics, these band gaps can be tuned to occur at low frequencies where the acoustic wavelength is large compared to the material, and where the performance of traditional passive noise control treatments is limited. Therefore, such acoustic metamaterials have been shown to offer a significant performance advantage compared to traditional passive control treatments, however, due to their resonant behaviour, the band gaps tend to occur over a relatively narrow frequency range. A similar long wavelength performance advantage can be achieved using active noise control, but the systems in this case do not rely on resonant behaviour. This paper demonstrates how the performance of an acoustic metamaterial, consisting of an array of Helmholtz resonators, can be significantly enhanced by the integration of an active control mechanism that is facilitated by embedding loudspeakers into the resonators. Crucially, it is then also shown how the active acoustic metamaterial significantly outperforms an equivalent traditional active noise control system. In both cases a broadband feedforward control strategy is employed to minimise the transmitted pressure in a one-dimensional acoustic control problem and a new method of weighting the control effort over a targeted frequency range is described.
11. Noise and Man . Noise as a Public Health Problem. Proceedings of the International Congress (6th) Held in Nice on July 5 - 9, 1993
1993-07-01
44 Pujol R Recent advances in cochlear neurobiology and new concepts in acoustic trauma...64 Puel JL Cochlear efferents and acoustic trauma...sensitive people. Effects on pregnancy remain unclear. To date, no chronic effect of noise such as increase of malformations has been observed, whereas the
12. Acoustical design of the new Cathay Pacific first class lounge
Hong, Westwood K. W.
Cathay Pacific Airways' requirement of a first class lounge for attracting the high-yield passenger market to Hong Kong presented a special challenge for the Acoustical consultant. The 500-seating lounge covers more than 2000 square meters and is claimed by Cathay to be the biggest in Asia for its first class passengers. Arup acoustics was required to design a space that provided a quiet and relaxed environment for the Commercial Important Persons after a 16 to 17-hour flight. Arup Acoustics has designed the acoustics of the Lounge in meeting a stringent low noise specification requested by the user. The design work gave a comprehensive service both to support the lead consultant Ova Arup & Partners in controlling the external aircraft noise and internal noise and to assist the architect and interior designer in providing an excellent acoustical atmosphere for the passengers to rest while waiting for an onward connection. This paper will discuss the design of the lightweight roof and special double glazing system, featured by a 20-mm-thick laminated glass for the outer pane and a 600 to 1000-mm air gap to combat aircraft noise at the Hong Kong International Airport.
13. Atlantic Herring Acoustic Surveys
National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Advanced Sampling Technologies Research Group conducts annual fisheries acoustic surveys using state-of-the-art acoustic, midwater trawling, and underwater...
14. Acoustic enhancement for photo detecting devices
Thundat, Thomas G; Senesac, Lawrence R; Van Neste, Charles W
2013-02-19
Provided are improvements to photo detecting devices and methods for enhancing the sensitivity of photo detecting devices. A photo detecting device generates an electronic signal in response to a received light pulse. An electro-mechanical acoustic resonator, electrically coupled to the photo detecting device, damps the electronic signal and increases the signal noise ratio (SNR) of the electronic signal. Increased photo detector standoff distances and sensitivities will result.
15. Active control of propeller induced noise fields inside a flexible cylinder
Lester, H. C.; Fuller, C. R.
1986-01-01
An active noise control model has been evaluated for reducing aircraft interior noise. The structural noise transmission properties of an aircraft fuselage were modelled as a flexible cylinder excited by external acoustic dipoles simulating the noise produced by twin propellers. The amplitudes of an internal distribution of monopole control sources were determined such that the area-weighted mean square acoustic pressure was minimized in the propeller plane. The noise control model was evaluated at low frequencies corresponding to the blade passage frequency and first few harmonics of a typical turbo-prop aircraft. Interior noise reductions of 20 25 dB were achieved, over a substantial region of the cylindrical cross-section, with just a few monopole control sources. The most favorable interior noise reductions were achieved when the active noise control model was used in combination with propeller source phasing.
16. NON-Shock-Plasticity/Fracture Burst Acoustic-Emission(BAE) 1''/f -Noise'' Power-Spectrum(PS) Power-Law UNIVERSALITY is Merely F =ma Time-Series Integral-Transform, aka Bak'' -SOC'' REdiscovery'' PRE(1687)-Bak'' (1988)
Siegel, Edward
2015-06-01
NON-shock plasticity/fracture BAE[E.S.:MSE 8,310(71); PSS:(a)5,601/607(71); Xl.-Latt.Defects 5,277(74); Scripta Met.:6,785(72); 8,587/617(74); 3rd Tokyo AE Symp.(76); Acta Met. 5,383(77); JMMM 7,312(78)] 1''/ ω-noise'' power-spectrum pink''-Zipf(NOT red'' =Pareto) power-law UNIVERSALITY is manifestly-demonstrated in two distinct ways to be nothing but Newton 3rd Law of Motion F = ma REdiscovery!!! (aka Bak''(1988)-SOC'':1687 0a<0) PS P(ω) = 1/ω 1 . 000 ... pink/flicker/HYPERBOLICITY.
17. Research on acoustic-structure sensitivity using FEM and BEM
ZHANG Jun; ZHAO Wenzhong; ZHANG Weiying
2007-01-01
Acoustic-structure sensitivity is used to predict the change of acoustic pressure when a structure design variable is changed. The sensitivity is significant for reducing noise of structure. Using FEM (finite element method) and BEM (boundary element method) acoustic-structure sensitiv- ity was formulated and presented. The dynamic response and response velocity sensitivity with respect to structure design variable were carried out by using structural FEM, the acous- tic response and acoustic pressure sensitivity with respect to structure velocity were carded out by using acoustic BEM. Then, acoustic-structure sensitivity was computed by linking velocity sensitivity in FEM and acoustic sensitivity in BEM. This method was applied to an empty box as an example. Acoustic pressure sensitivity with respect to structure thick- ness achieved in frequency ranges 1-100 Hz, and its change role along with stimulating frequency and design variable were analyzed. Results show that acoustic-structure sensi- tivity method linked with FEM and BEM is effective and correct.
18. Hybrid CFD/CAA Modeling for Liftoff Acoustic Predictions
Strutzenberg, Louise L.; Liever, Peter A.
2011-01-01
This paper presents development efforts at the NASA Marshall Space flight Center to establish a hybrid Computational Fluid Dynamics and Computational Aero-Acoustics (CFD/CAA) simulation system for launch vehicle liftoff acoustics environment analysis. Acoustic prediction engineering tools based on empirical jet acoustic strength and directivity models or scaled historical measurements are of limited value in efforts to proactively design and optimize launch vehicles and launch facility configurations for liftoff acoustics. CFD based modeling approaches are now able to capture the important details of vehicle specific plume flow environment, identifY the noise generation sources, and allow assessment of the influence of launch pad geometric details and sound mitigation measures such as water injection. However, CFD methodologies are numerically too dissipative to accurately capture the propagation of the acoustic waves in the large CFD models. The hybrid CFD/CAA approach combines the high-fidelity CFD analysis capable of identifYing the acoustic sources with a fast and efficient Boundary Element Method (BEM) that accurately propagates the acoustic field from the source locations. The BEM approach was chosen for its ability to properly account for reflections and scattering of acoustic waves from launch pad structures. The paper will present an overview of the technology components of the CFD/CAA framework and discuss plans for demonstration and validation against test data.
19. The Effects of Sediment Properties on Low Frequency Acoustic Propagation
2013-09-30
Experimental observations and seismo-acoustic inversions,” J. Acoust. Soc. Am. 110 (4), 1908-1916, 2001. 4. D. Rauch, “ Seismic interface waves in coastal...Predicting underwater radiated noise levels due to the first offshore wind turbine installation in the U.S.,” POMA 19, 040067 (2013). 21. Edward...offshore wind turbine noise using finite element and parabolic equation models”. This paper was co- authored by Gopu R. Potty, James H. Miller, Kevin B. Smith, and Georges Dossot.
20. Vortex noise from nonrotating cylinders and airfoils
Schlinker, R. H.; Amiet, R. K.; Fink, M. R.
1976-01-01
An experimental study of vortex-shedding noise was conducted in an acoustic research tunnel over a Reynolds-number range applicable to full-scale helicopter tail-rotor blades. Two-dimensional tapered-chord nonrotating models were tested to simulate the effect of spanwise frequency variation on the vortex-shedding mechanism. Both a tapered circular cylinder and tapered airfoils were investigated. The results were compared with data for constant-diameter cylinder and constant-chord airfoil models also tested during this study. Far-field noise, surface pressure fluctuations, and spanwise correlation lengths were measured for each configuration. Vortex-shedding noise for tapered cylinders and airfoils was found to contain many narrowband-random peaks which occurred within a range of frequencies corresponding to a predictable Strouhal number referenced to the maximum and minimum chord. The noise was observed to depend on surface roughness and Reynolds number.
1. [Effects of noise on inner ear].
Bouccara, Didier; Ferrary, Evelyne; Sterkers, Olivier
2006-11-01
The effects of noise on health depend both on individual factors and characteristics of sound exposure. In case of acoustic trauma, reversible or irreversible lesions of inner ear components are possible. Most often there is immediately an acute tinnitus and hearing loss. Audiometric tests demonstrate hearing loss on the high frequency, generally focused on 4 kHz. Immediate treatment is recommended even there is no currently indicator of the ability to restore hearing. New perspectives on treatment are directed to local treatment and/or using new procedure as antioxidative treatment. Occupational and leisure are the two conditions in which chronic exposure to noise is found. Detection and prevention of noise-induced hearing loss is easier in case of industrial workers than in case of noise exposition for musicians and other sounds and stage technicians or concert managers, and of course non-professional with exposure to amplified music.
2. Sound reduction by metamaterial-based acoustic enclosure
Shanshan Yao
2014-12-01
Full Text Available In many practical systems, acoustic radiation control on noise sources contained within a finite volume by an acoustic enclosure is of great importance, but difficult to be accomplished at low frequencies due to the enhanced acoustic-structure interaction. In this work, we propose to use acoustic metamaterials as the enclosure to efficiently reduce sound radiation at their negative-mass frequencies. Based on a circularly-shaped metamaterial model, sound radiation properties by either central or eccentric sources are analyzed by numerical simulations for structured metamaterials. The parametric analyses demonstrate that the barrier thickness, the cavity size, the source type, and the eccentricity of the source have a profound effect on the sound reduction. It is found that increasing the thickness of the metamaterial barrier is an efficient approach to achieve large sound reduction over the negative-mass frequencies. These results are helpful in designing highly efficient acoustic enclosures for blockage of sound in low frequencies.
3. Passive Acoustic Radar for Detecting Supersonic Cruise Missile
XIAO Feng; XIAO Hui
2005-01-01
A Passive Acoustic Radar is presented as a necessary complement to electromagnetic wave radar, which will be expected to be an effective means for detecting cruise missiles. Acoustic characteristics of supersonic flying projectiles with diverse shapes are expounded via experiment. It is pointed out that simulation experiment could be implemented using bullet or shell instead of cruise missile. Based on theoretical analysis and experiment, the "acoustic fingerprint" character of cruise missile is illustrated to identify it in a strong noise environment. After establishing a locating mathematical model,the technique of acoustic embattling is utilized to resolve a problem of confirming the time of early-warning, considering the fact that velocity of sound is much slower than that of light. Thereby, a whole system of passive acoustic radar for detecting supersonic cruise missile is formed.
4. The acoustics of aircraft engine-duct systems
Nayfeh, A. H.; Kaiser, J. E.; Telionis, D. P.
1973-01-01
Noise generated in aircraft engines is usually suppressed by acoustically treating the engine ducts. The optimization of this treatment requires an understanding of the transmission and attenuation of the acoustic waves. A critical review is presented of the state of the art regarding methods of determining the transmission and attenuation parameters and the effect on these parameters of (1) acoustic properties of liners, (2) the mean velocity, including uniform and shear profiles and nonparallel flow, (3) axial and transverse temperature gradients, (4) slowly and abruptly varying cross sections, and (5) finite-amplitude waves and nonlinear duct liners.
5. Localization of acoustic sensors from passive Green's function estimation.
Nowakowski, Thibault; Daudet, Laurent; de Rosny, Julien
2015-11-01
A number of methods have recently been developed for passive localization of acoustic sensors, based on the assumption that the acoustic field is diffuse. This article presents the more general case of equipartition fields, which takes into account reflections off boundaries and/or scatterers. After a thorough discussion on the fundamental differences between the diffuse and equipartition models, it is shown that the method is more robust when dealing with wideband noise sources. Finally, experimental results show, for two types of boundary conditions, that this approach is especially relevant when acoustic sensors are close to boundaries.
6. Metamaterial based embedded acoustic filters for structural applications
Hongfei Zhu
2013-09-01
Full Text Available We investigate the use of acoustic metamaterials to design structural materials with frequency selective characteristics. By exploiting the properties of acoustic metamaterials, we tailor the propagation characteristics of the host structure to effectively filter the constitutive harmonics of an incoming broadband excitation. The design approach exploits the characteristics of acoustic waveguides coupled by cavity modes. By properly designing the cavity we can tune the corresponding resonant mode and, therefore, coupling the waveguide at a prescribed frequency. This structural design can open new directions to develop broadband passive vibrations and noise control systems fully integrated in structural components.
7. In plant partial noise enclosures for the mining industry
Kinevy, P.T.
1993-10-01
The Physical and Toxic Agents Division of the Mine Safety and Health Administrations Pittsburgh Safety and Health Technology Center has conducted three joint noise control demonstrations at dry milling operations. These demonstrations were conducted on a rod mill, a roller mill, and a ball mill, in order to survey a representative sample of the more commonly utilized types of milling equipment. The noise control concept that was demonstrated involved the construction of partial enclosures surrounding the mills and then adding acoustical materials within the enclosures to absorb the build up of acoustical energy. The results of this work illustrate the feasibility of this concept, the physical principle of creating an acoustical shadow, and the ability to closely predict the amount of absorptive material required to reduce the noise levels so as to comply with the Code of Federal Regulations (CFR), Title 30.
8. The role of classroom acoustics on vocal intensity regulation and speakers’ comfort
Pelegrin Garcia, David
investigated the relationships between the classroom acoustic condition and teachers’ voice, focusing on their vocal intensity, and between the classroom acoustic condition and the sensation of acoustic comfort for a speaker. In the presence of low background noise levels, teachers were found to adjust...... in average teacher-to-student distance, but some of the variation was due to the room acoustic condition. The amount of vocal intensity variation with the room acoustic condition increased with the distance between teacher and student. In field measurements performed during typical working days, teachers......Teachers are one of the professional groups with the highest risk of suffering from voice disorders. Teachers point out classroom acoustics among the potential hazards affecting their vocal health, together with air dryness, background noise, and other environmental factors. The present project has...
9. Speech recognition in natural background noise.
Julien Meyer
Full Text Available In the real world, human speech recognition nearly always involves listening in background noise. The impact of such noise on speech signals and on intelligibility performance increases with the separation of the listener from the speaker. The present behavioral experiment provides an overview of the effects of such acoustic disturbances on speech perception in conditions approaching ecologically valid contexts. We analysed the intelligibility loss in spoken word lists with increasing listener-to-speaker distance in a typical low-level natural background noise. The noise was combined with the simple spherical amplitude attenuation due to distance, basically changing the signal-to-noise ratio (SNR. Therefore, our study draws attention to some of the most basic environmental constraints that have pervaded spoken communication throughout human history. We evaluated the ability of native French participants to recognize French monosyllabic words (spoken at 65.3 dB(A, reference at 1 meter at distances between 11 to 33 meters, which corresponded to the SNRs most revealing of the progressive effect of the selected natural noise (-8.8 dB to -18.4 dB. Our results showed that in such conditions, identity of vowels is mostly preserved, with the striking peculiarity of the absence of confusion in vowels. The results also confirmed the functional role of consonants during lexical identification. The extensive analysis of recognition scores, confusion patterns and associated acoustic cues revealed that sonorant, sibilant and burst properties were the most important parameters influencing phoneme recognition. . Altogether these analyses allowed us to extract a resistance scale from consonant recognition scores. We also identified specific perceptual consonant confusion groups depending of the place in the words (onset vs. coda. Finally our data suggested that listeners may access some acoustic cues of the CV transition, opening interesting perspectives for
10. Acoustic Communications (ACOMMS) ATD
2016-06-14
develop and demonstrate emerging undersea acoustic communication technologies at operationally useful ranges and data rates. The secondary objective...Technology Demonstration program (ACOMMS ATD) was to demonstrate long range and moderate data rate underwater acoustic communications between a submarine...moderate data rate acoustic communications capability for tactical use between submarines, surface combatants, unmanned undersea vehicles (UUVs), and other
11. Tutorial on architectural acoustics
Shaw, Neil; Talaske, Rick; Bistafa, Sylvio
2002-11-01
This tutorial is intended to provide an overview of current knowledge and practice in architectural acoustics. Topics covered will include basic concepts and history, acoustics of small rooms (small rooms for speech such as classrooms and meeting rooms, music studios, small critical listening spaces such as home theatres) and the acoustics of large rooms (larger assembly halls, auditoria, and performance halls).
12. Noise-reducing designs of machines and structures
N Tandon
2000-06-01
It is advisable and better to consider noise control measures at the design stage itself rather than after the product is manufactured and installed. The present paper describes some of the control measures that can be incorporated during the design of machines and structures. Vibration control, barriers and enclosures can be used for noise control and should be considered at the design stage. Acoustical materials which can be used for noise control purpose have been described. Some examples of noise-reducing design are also given.
13. The influence of the noise environment on crew communications
Leverton, J. W.
1978-01-01
The noise environment and how it affects crew communications in helicopters is considered. The signal to noise (S/N) ratio at the microphone and the effect of the attenuation provided by the helmet is discussed. This shows that the most important aspect is the S/N ratio at the microphone, particularly when helmets with improved attenuation characteristics are considered. Evidence is presented which shows that in high noise environments, the system S/N ratio is well below that required and hence there is an urgent need to reduce the cabin noise levels and improve the microphone rejection properties. Emphasis is placed on environmental/acoustic considerations.
14. Mapping cumulative noise from shipping to inform marine spatial planning.
Erbe, Christine; MacGillivray, Alexander; Williams, Rob
2012-11-01
Including ocean noise in marine spatial planning requires predictions of noise levels on large spatiotemporal scales. Based on a simple sound transmission model and ship track data (Automatic Identification System, AIS), cumulative underwater acoustic energy from shipping was mapped throughout 2008 in the west Canadian Exclusive Economic Zone, showing high noise levels in critical habitats for endangered resident killer whales, exceeding limits of "good conservation status" under the EU Marine Strategy Framework Directive. Error analysis proved that rough calculations of noise occurrence and propagation can form a basis for management processes, because spending resources on unnecessary detail is wasteful and delays remedial action.
15. Analysis of broadband aerodynamic noise from VS45
Dundabin, P. [Renewable Energy Systems Ltd., Glasgow, Scotland (United Kingdom)
1997-12-31
This paper describes the analysis of acoustic data taken from the VS45 at Kaiser-Wilhelm-Koog. The aim was to investigate the dependence of aerodynamic noise on tip speed and angle of attack. In particular, the dependence of noise in individual third octave bands on these variable is examined. The analysis is divided into 3 sections: data selection, data checks and analysis of broadband nacelle noise; analysis of broadband aerodynamic noise and its sensitivity to tip speed and angle of attack. (LN)
16. Vortex shedding noise of a cylinder with hairy flaps
Kamps, L.; Geyer, T. F.; Sarradj, E.; Brücker, C.
2017-01-01
This study describes the modification of acoustic noise emitted from cylinders in a stationary subsonic flow for a cylinder equipped with flexible hairy flaps at the aft part as a passive way to manipulate the flow and acoustics. The study was motivated by the results from previous water tunnel measurements, which demonstrated that hairy flaps can modify the shedding cycle behind the cylinder and can reduce the wake deficit. In the present study, wind tunnel experiments were conducted on such...
17. Study of engine noise based on independent component analysis
HAO Zhi-yong; JIN Yan; YANG Chen
2007-01-01
Independent component analysis was applied to analyze the acoustic signals from diesel engine. First the basic principle of independent component analysis (ICA) was reviewed. Diesel engine acoustic signal was decomposed into several independent components (Ics); Fourier transform and continuous wavelet transform (CWT) were applied to analyze the independent components. Different noise sources of the diesel engine were separated, based on the characteristics of different component in time-frequency domain.
18. Landing Gear Door Liners for Airframe Noise Reduction
Jones, Michael G. (Inventor); Howerton, Brian M. (Inventor); Van De Ven, Thomas (Inventor)
2014-01-01
A landing gear door for retractable landing gear of aircraft includes an acoustic liner. The acoustic liner includes one or more internal cavities or chambers having one or more openings that inhibit the generation of sound at the surface and/or absorb sound generated during operation of the aircraft. The landing gear door may include a plurality of internal chambers having different geometries to thereby absorb broadband noise.
19. SELECTED PROBLEMS OF PROTECTION AGAINST ROAD TRAFFIC NOISE
2015-11-01
Full Text Available The paper presents factors for assessment of road traffic noise level and possible actions towards the minimization of excessive noise in the roadway neighborhood. Changes of equivalent sound level values were analyzed in relation to traffic intensity, categorization and vehicles speed. In relation to measures reducing noise level in roadway’s surroundings particular attention was given to anti-noise protections and tyre/noise reduction. Acoustic effectiveness of specific solutions was showed based on chosen examples. It was proved that when admissible noise level is slightly exceeded the need for noise barrier use may be replaced by a proper design and maintenance of road pavement or by enforcement of speed limit.
20. Noise levels of dental equipment used in dental college of Damascus University
Mhd. Loutify Qsaibati; Ousama Ibrahim
2014-01-01
Background: In dental practical classes, the acoustic environment is characterized by high noise levels in relation to other teaching areas. The aims of this study were to measure noise levels produced during the different dental learning clinics, by equipments used in dental learning areas under different working conditions and by used and brand new handpieces under different working conditions. Materials and Methods: The noise levels were measured by using a noise level meter with a mic...
1. Assessment of noise levels of the equipments used in the dental teaching institution, Bangalore
2011-01-01
Context: In dental practical classes, the acoustic environment is characterized by high noise levels in relation to other teaching areas, due to the exaggerated noise produced by some of these devices and use of dental equipment by many users at the same time. Aims: To measure, analyze and compare noise levels of equipments among dental learning areas under different working conditions and also to measure and compare noise levels between used and brand new handpieces under different worki...
2. The development of technologies and devices for protection from noise generated by power equipment
Mikhailov, V. E.; Khomenok, L. A.; Yablonik, L. R.
2010-01-01
The main lines of currently conducted research and development activities on suppressing noise produced by power-generating equipment are presented. Matters related to preventing the occurrence of aeroacoustic self-excited vibrations, optimizing dissipative noise silencers, using structural methods for damping acoustic vibrations, suppressing low-frequency noise, and analyzing the effectiveness of soundproof coatings are considered. The process diagrams and parameters of devices for suppressing noise generated during discharge into the atmosphere of high-pressure gaseous media are discussed.
3. Evaluation of acoustic shock induced early hearing loss with audiometer and distortion product otoacoustic emissions
2010-01-01
Background: Acoustic shock injury has been described as a permanent injury to the auditory system either due to daily noise dose of in excess of 85 decibels or very loud impulse sound reputed to be in excess of 120 decibels and acoustic incidents. This study was performed to compare the results of audiogram and the newer diagnostic method distortion product otoacoustic emissions (DPOAEs) parameters due to acoustic shock injury in call center professionals working in a noisy environment and pr...
4. A comparative study of varying fan noise mitigation techniques in relation to sustainable design goals
Overweg, Cornelis; Fullerton, Jeff L.
2005-04-01
Green building design promotes effective use of materials and energy, improved indoor environmental quality (IEQ), and enhanced occupant comfort. These `green'' goals can occasionally conflict with common acoustical approaches used for fan noise control. A design striving for low noise levels from the ventilation system to benefit occupant comfort can inadvertently introduce elements that are contradictory to other green building objectives. For example, typical fan noise control devices introduce higher energy consumption or less beneficial indoor environmental quality. This paper discusses the acoustical, mechanical, environmental, and relative cost impacts of various fan noise control techniques.
5. Using rotor or tip speed in the acoustical analysis of small wind turbines
Acoustical noise data have been collected and analyzed on small wind turbines used for water pumping at the USDA-ARS Conservation and Production Research Laboratory (CPRL) near Bushland, Texas. This acoustical analysis differed from previous research in that the data were analyzed with rotor or tip ...
6. Acoustic pollution in hospital environments
Olivera, J. M.; Rocha, L. A.; Rotger, V. I.; Herrera, M. C.
2011-12-01
There are many different services within a hospital. This means different types of noise which can be considered as acoustic pollution. Knowing that preterm infants exposed to high amounts of noise in the NICU are at a much higher risk because of their neurologic immaturity and physiologic instability, that excessive levels of noise also affect the persons and it can also impede some studies on patients, it was proposed to evaluate the Sound Pressure Level in some services of the Instituto de Maternidad, Tucumán, Argentina. There were evaluated the Level III NICU, the laundry service, a physical space destined for a service of evoked potential and a neonatal incubator under working conditions. The measurements were performed with a type II sonometer (CENTER 322) and it was also used an incubator analyzer (FLUKE INCU) for the incubator. The average values obtained were of 63.6 dBA for the NICU, 82.5dBA for the laundry room, 52.7 dBA for the evoked potential room and 62.8 dBA in the inside of the incubator under 64 dBA in the outside. The reports were documented in compliance with the appropriate standards.
7. Unstructured, High-Order Scheme Module with Low Dissipation Flux Difference Splitting for Noise Prediction Project
National Aeronautics and Space Administration — Thorough understanding of aircraft airframe and engine noise mechanisms and the subsequent acoustic propagation to the farfield is necessary to develop and evaluate...
8. Acoustic elliptical cylindrical cloaks
Ma Hua; Qu Shao-Bo; Xu Zhuo; Wang Jia-Fu
2009-01-01
By making a comparison between the acoustic equations and the 2-dimensional (2D) Maxwell equations, we obtain the material parameter equations (MPE) for acoustic elliptical cylindrical cloaks. Both the theoretical results and the numerical results indicate that an elliptical cylindrical cloak can realize perfect acoustic invisibility when the spatial distributions of mass density and bulk modulus are exactly configured according to the proposed equations. The present work is the meaningful exploration of designing acoustic cloaks that are neither sphere nor circular cylinder in shape, and opens up possibilities for making complex and multiplex acoustic cloaks with simple models such as spheres, circular or elliptic cylinders.
9. Indoor acoustic gain design
Concha-Abarca, Justo Andres
2002-11-01
The design of sound reinforcement systems includes many variables and usually some of these variables are discussed. There are criteria to optimize the performance of the sound reinforcement systems under indoor conditions. The equivalent acoustic distance, the necessary acoustic gain, and the potential acoustic gain are parameters which must be adjusted with respect to the loudspeaker array, electric power and directionality of loudspeakers, the room acoustics conditions, the distance and distribution of the audience, and the type of the original sources. The design and installation of front of the house and monitoring systems have individual criteria. This article is about this criteria and it proposes general considerations for the indoor acoustic gain design.
10. Biological Environmental Acoustics on the Investigations for Birds Sing with Road Traffic Noise%鸟鸣声与道路交通噪声的生物环境声学研究
张继萍; 阎浩; 周晞噜; 朱生晖; 叶旭红; 杨乐
2013-01-01
The investigations on birds sing in the references are mainly on the view of birds protection, the promotion to the sonic environment or soundscape, and the impact to the environments. The former part also includes the investigating on bird survival behavior, communication, emotional expression on the biological natural characters, and mainly on the impact, interrupt, and destroy from human beings to birds. By reading the references in Chinese and the abroad, this paper comments the birds sing investigatings in China, the relationships with the road traffic noise, and the applications on soundscape protection and design.%关于鸟鸣声的研究包括了从保护鸟类的角度，以及鸟鸣声对改善声环境（声景观）和影响声环境的角度。前者又包括了对鸟类生存行为、互相通信、情绪表达的生物自然生态特性研究，以及人为环境噪声对鸟类这些活动的干扰甚至破坏的影响。通过国内外文献，调研了我国鸟鸣声研究的进展，及其与道路交通噪声的关系。
11. A jet engine noise measurement and prediction tool.
2002-11-01
In this paper, the authors describe an innovative jet engine noise measurement and prediction tool. The tool measures sound-pressure levels and frequency spectra in the far field. In addition, the tool provides predicted results while the measurements are being made. The predictions are based on an existing computational fluid dynamics database coupled to an empirical acoustic radiation model based on the far-field approximation to the Lighthill acoustic analogy. Preliminary tests of this acoustic measurement and prediction tool produced very encouraging results.
12. Analysis of noise pollution in an andesite quarry with the use of simulation studies and evaluation indices.
Kosała, Krzysztof; Stępień, Bartłomiej
2016-01-01
This paper presents the verification of two partial indices proposed for the evaluation of continuous and impulse noise pollution in quarries. These indices, together with the sound power of machines index and the noise hazard index at the workstation, are components of the global index of assessment of noise hazard in the working environment of a quarry. This paper shows the results of acoustic tests carried out in an andesite quarry. Noise generated by machines and from performed blasting works was investigated. On the basis of acoustic measurements carried out in real conditions, the sound power levels of machines and the phenomenon of explosion were determined and, based on the results, three-dimensional models of acoustic noise propagation in the quarry were developed. To assess the degree of noise pollution in the area of the quarry, the continuous and impulse noise indices were used.
13. When ambient noise impairs parent-offspring communication.
Lucass, Carsten; Eens, Marcel; Müller, Wendt
2016-05-01
Ambient noise has increased in extent, duration and intensity with significant implications for species' lives. Birds especially, because they heavily rely on vocal communication, are highly sensitive towards noise pollution. Noise can impair the quality of a territory or hamper the transmission of vocal signals such as song. The latter has significant fitness consequences as it may erode partner preferences in the context of mate choice. Additional fitness costs may arise if noise masks communication between soliciting offspring and providing parents during the period of parental care. Here, we experimentally manipulated the acoustic environment of blue tit (Cyanistes caeruleus) families within their nest boxes with playbacks of previously recorded highway noise and investigated the consequences on parent-offspring communication. We hypothesized that noise interferes with the acoustic cues of parental arrival and vocal components of offspring begging. As such we expected an increase in the frequency of missed detections, when nestlings fail to respond to the returning parent, and a decrease in parental provisioning rates. Parents significantly reduced their rate of provisioning in noisy conditions compared to a control treatment. This reduction is likely to be the consequence of a parental misinterpretation of the offspring hunger level, as we found that nestlings fail to respond to the returning parent more frequently in the presence of noise. Noise also potentially masks vocal begging components, again contributing to parental underestimation of offspring requirements. Either way, it appears that noise impaired parent-offspring communication is likely to reduce reproductive success.
14. Proceedings of the Spring noise conference 2011: what's the buzz?: innovations and issues
NONE
2011-07-01
This event is a global conference that attracts delegates and speakers from around the world to talk about environmental and occupational noise. The conference provides industry, government, the public, academics and acoustical professionals worldwide with the opportunity to share experiences and innovations in environmental and applied acoustics; specifically noise identification, measurement, regulation and control. Presentation of new research, technical developments, and case studies were given during the event. All 21 presentations from the conference were processed separately for inclusion in this database.
15. Monitoring of traffic noise in an urban area using a wireless sensor network
Wessels, P.W.; Basten, T.G.H.; Eerden, F.J.M. van der; Graafland, F.
2014-01-01
Developments in systems for monitoring environmental noise have made it possible to monitor the acoustic situation within large urban areas. The developments in hardware size and costs, combined with the developments in wireless communication allow to deploy networks with many acoustic sensors witho
16. Investigation on experimental techniques to detect, locate and quantify gear noise in helicopter transmissions
Flanagan, P. M.; Atherton, W. J.
1985-01-01
A robotic system to automate the detection, location, and quantification of gear noise using acoustic intensity measurement techniques has been successfully developed. Major system components fabricated under this grant include an instrumentation robot arm, a robot digital control unit and system software. A commercial, desktop computer, spectrum analyzer and two microphone probe complete the equipment required for the Robotic Acoustic Intensity Measurement System (RAIMS). Large-scale acoustic studies of gear noise in helicopter transmissions cannot be performed accurately and reliably using presently available instrumentation and techniques. Operator safety is a major concern in certain gear noise studies due to the operating environment. The man-hours needed to document a noise field in situ is another shortcoming of present techniques. RAIMS was designed to reduce the labor and hazard in collecting data and to improve the accuracy and repeatability of characterizing the acoustic field by automating the measurement process. Using RAIMS a system operator can remotely control the instrumentation robot to scan surface areas and volumes generating acoustic intensity information using the two microphone technique. Acoustic intensity studies requiring hours of scan time can be performed automatically without operator assistance. During a scan sequence, the acoustic intensity probe is positioned by the robot and acoustic intensity data is collected, processed, and stored.
17. Description of Anomalous Noise Events for Reliable Dynamic Traffic Noise Mapping in Real-Life Urban and Suburban Soundscapes
Francesc Alías
2017-02-01
Full Text Available Traffic noise is one of the main pollutants in urban and suburban areas. European authorities have driven several initiatives to study, prevent and reduce the effects of exposure of population to traffic. Recent technological advances have allowed the dynamic computation of noise levels by means of Wireless Acoustic Sensor Networks (WASN such as that developed within the European LIFE DYNAMAP project. Those WASN should be capable of detecting and discarding non-desired sound sources from road traffic noise, denoted as anomalous noise events (ANE, in order to generate reliable noise level maps. Due to the local, occasional and diverse nature of ANE, some works have opted to artificially build ANE databases at the cost of misrepresentation. This work presents the production and analysis of a real-life environmental audio database in two urban and suburban areas specifically conceived for anomalous noise events’ collection. A total of 9 h 8 min of labelled audio data is obtained differentiating among road traffic noise, background city noise and ANE. After delimiting their boundaries manually, the acoustic salience of the ANE samples is automatically computed as a contextual signal-to-noise ratio (SNR. The analysis of the real-life environmental database shows high diversity of ANEs in terms of occurrences, durations and SNRs, as well as confirming both the expected differences between the urban and suburban soundscapes in terms of occurrences and SNRs, and the rare nature of ANE.
18. Study on Noise Reduction Performance of Sound Barrier with Acoustic Diffusers%顶端结构为声扩散体的声屏障降噪性能研究
吴文高; 蔡俊; 刘玲
2012-01-01
In this paper several kinds of basic common Schroeder diffusers were introduced, and the diffusers were applied on the top of sound barrier. Using boundary element method, the sound barrier structure model was simulated. Significant effects of noise reduction of all diffusers were found in low frequency range with 3?5dB higher than traditional sound barrier. Also it was found that prime root diffuser (PRD) has the better insertion losses up to 0.61-1.52 dB than other diffusers at the 5 m distance back of the sound barriers. The result will provide an important reference to apply sound diffusers on the sound barrier.%介绍几种基本常见的Schroeder扩散体并分别应用于声屏障顶端.应用边界元法对扩散体声屏障的结构模型进行了模拟计算.发现所有扩散体型声屏障降噪效果显著,在低频均有非常好的降噪效果且低频降噪量比传统的声屏障要高3～5 dB.同时发现素根序列(PRD)扩散体整体降噪效果最优,其在声屏障5m后其降噪效果和其它类型的扩散体型声屏障比较,其插入损失要高0.61～1.52 dB,这为以后声扩散体应用于声屏障的工程应用提供了参考依据.
19. Investigation of noise production from a turbulent cylinder
Nitzkorski, Zane; Mahesh, Krishnan
2011-11-01
We investigate noise production by a cylinder in turbulent flow (Re = 10,000 and M = 0.2), using the Ffowcs-Williams and Hawkings acoustic analogy, where the sound sources are computed from a compressible direct numerical simulation. It has been shown that vortices passing through a data surface generate spurious noise if the quadrupole term is neglected. Our implementation of the acoustic analogy, hence, uses porous data surfaces as well as the volume term. We compare our solution to available results, examine the effect of the placement of the data surface on the noise calculation by using multiple surfaces, and the effect of different proposed correction schemes that try to compensate for neglecting the quadrupole noise.
20. Low-frequency noise reduction of lightweight airframe structures
Getline, G. L.
1976-01-01
The results of an experimental study to determine the noise attenuation characteristics of aircraft type fuselage structural panels were presented. Of particular interest was noise attenuation at low frequencies, below the fundamental resonances of the panels. All panels were flightweight structures for transport type aircraft in the 34,050 to 45,400 kg (75,000 to 100,000 pounds) gross weight range. Test data include the results of vibration and acoustic transmission loss tests on seven types of isotropic and orthotropically stiffened, flat and curved panels. The results show that stiffness controlled acoustically integrated structures can provide very high noise reductions at low frequencies without significantly affecting their high frequency noise reduction capabilities.
1. Bubble-bubble interaction: A potential source of cavitation noise
Ida, Masato
2009-01-01
The interaction between microbubbles through pressure pulses has been studied to show that it can be a source of cavitation noise. A recent report demonstrated that the acoustic noise generated by a shrimp originates from the collapse of a cavitation bubble produced when the shrimp closes its snapper claw. The recorded acoustic signal contains a broadband noise that consists of positive and negative pulses, but a theoretical model for single bubbles fails to reproduce the negative ones. Using a nonlinear multibubble model we have shown here that the negative pulses can be explained by considering the interaction of microbubbles formed after the cavitation bubble has collapsed and fragmented: Positive pulses produced at the collapse of the microbubbles hit and impulsively compress neighboring microbubbles to generate reflected pulses whose amplitudes are negative. Discussing the details of the noise generation process, we have found that no negative pulses are generated if the internal pressure of the reflecti...
2. Air-borne noise of thermal module and system for notebook personal computers:experimental study
2008-01-01
Thermal performance is the most important issue to be considered when a thermal module is designed for a notebook personal computer (PC).Because the fan causes air-borne noise and affects the user's comfort,the acoustic characteristics of the module attract more attention.Experiments were conducted to study the noise sources,the noise characteristic and the main factors influencing the noise level.The difference between the air-borne noise of the thermal module and the whole computer system was analyzed and its propagating characteristics were derived.The influence of I/O ports on the air-borne noise was also studied experimentally.
3. Wind turbines. Unsteady aerodynamics and inflow noise
Riget Broe, B.
2009-12-15
Aerodynamical noise from wind turbines due to atmospheric turbulence has the highest emphasis in semi-empirical models. However it is an open question whether inflow noise has a high emphasis. This illustrates the need to investigate and improve the semi-empirical model for noise due to atmospheric turbulence. Three different aerodynamical models are investigated in order to estimate the lift fluctuations due to unsteady aerodynamics. Two of these models are investigated to find the unsteady lift distribution or pressure difference as function of chordwise position on the aerofoil. An acoustic model is investigated using a model for the lift distribution as input. The two models for lift distribution are used in the acoustic model. One of the models for lift distribution is for completely anisotropic turbulence and the other for perfectly isotropic turbulence, and so is also the corresponding models for the lift fluctuations derived from the models for lift distribution. The models for lift distribution and lift are compared with pressure data which are obtained by microphones placed flush with the surface of an aerofoil. The pressure data are from two experiments in a wind tunnel, one experiment with a NACA0015 profile and a second with a NACA63415 profile. The turbulence is measured by a triple wired hotwire instrument in the experiment with a NACA0015 profile. Comparison of the aerodynamical models with data shows that the models capture the general characteristics of the measurements, but the data are hampered by background noise from the fan propellers in the wind tunnel. The measurements are in between the completely anisotropic turbulent model and the perfectly isotropic turbulent model. This indicates that the models capture the aerodynamics well. Thus the measurements suggest that the noise due to atmospheric turbulence can be described and modeled by the two models for lift distribution. It was not possible to test the acoustical model by the measurements
4. Noise and vibration control in aircraft: A global approach
Berhault, J.-P.; Venet, G.; Fontenot, J.
This paper proposes an approach to noise and vibration control in new and existing aircraft, employing a global approach; that is, considering all source and effects in development of the control plan. The approach employs acoustic imaging of the engines and the cabin internal space and a vibration analysis model to describe the entire system. Completion of the global analysis leads to the treatment plan, which may include various passive mounts tecnologies and/or an active noise system.
5. Inhibitory noise
Alain Destexhe
2010-03-01
Full Text Available Cortical neurons in vivo may operate in high-conductance states, in which the major part of the neuron's input conductance is due to synaptic activity, sometimes several-fold larger than the resting conductance. We examine here the contribution of inhibition in such high-conductance states. At the level of the absolute conductance values, several studies have shown that cortical neurons in vivo are characterized by strong inhibitory conductances. However, conductances are balanced and spiking activity is mostly determined by fluctuations, but not much is known about excitatory and inhibitory contributions to these fluctuations. Models and dynamic-clamp experiments show that, during high-conductance states, spikes are mainly determined by fluctuations of inhibition, or by inhibitory noise. This stands in contrast to low-conductance states, in which excitatory conductances determine spiking activity. To determine these contributions from experimental data, maximum likelihood methods can be designed and applied to intracellular recordings in vivo. Such methods indicate that action potentials are indeed mostly correlated with inhibitory fluctuations in awake animals. These results argue for a determinant role for inhibitory fluctuations in evoking spikes, and do not support feed-forward modes of processing, for which opposite patterns are predicted.
6. Peculiarities of hearing impairment depending on interaction with acoustic stimuli
Myshchenko, Iryna; Nazarenko, Vasyl; Kolganov, Anatoliy; Tereshchenko, Pavlo
2015-01-01
Aims: The functional state of the auditory analyzer of several operators groups was study. The objective of this study was to determine some characteristics of hearing impairment in relation with features of acoustic stimuli and informative significance of noise. Materials and Methods: 236 employees (middle age 35.4 ± 0.74 years) were divided into four groups according to features of noise perception at the workplaces. The levels of permanent shifts of acoustic thresholds were estimated using audiometric method. Statistical Analysis Used: Common statistical methods were used in research. Mean quantity and mean absolute errors were calculated. Statistical significance between operators' groups was calculated with 0.05 confidential intervals. Results: The peculiarities of hearing impairment in observed groups were different. Operators differentiating acoustic signals had peak of hearing impairment in the field of language frequencies, while the employees who work with noise background at the workplaces had maximal hearing threshold on the 4000 Hz frequency (P ≤ 0.05). Conclusions: Hearing impairment depends both on energy and human interaction with acoustic irritant. The distinctions in hearing impairment may be related with the necessity of recognizing of acoustic signals and their frequency characteristics. PMID:26957812
7. Measurement with verification of stationary signals and noise in extremely quiet environments: measuring below the noise floor.
Ellingson, Roger M; Gallun, Frederick J; Bock, Guillaume
2015-03-01
It can be problematic to measure stationary acoustic sound pressure level in any environment when the target level approaches or lies below the minimum measureable sound pressure level of the measurement system itself. This minimum measureable level, referred to as the inherent measurement system noise floor, is generally established by noise emission characteristics of measurement system components such as microphones, preamplifiers, and other system circuitry. In this paper, methods are presented and shown accurate measuring stationary levels within 20 dB above and below this system noise floor. Methodology includes (1) measuring inherent measurement system noise, (2) subtractive energy based, inherent noise adjustment of levels affected by system noise floor, and (3) verifying accuracy of inherent noise adjustment technique. While generalizable to other purposes, the techniques presented here were specifically developed to quantify ambient noise levels in very quiet rooms used to evaluate free-field human hearing thresholds. Results obtained applying the methods to objectively measure and verify the ambient noise level in an extremely quiet room, using various measurement system noise floors and analysis bandwidths, are presented and discussed. The verified results demonstrate the adjustment method can accurately extend measurement range to 20 dB below the measurement system noise floor, and how measurement system frequency bandwidth can affect accuracy of reported noise levels.
8. Noise and Hearing Protection
... ENTCareers Marketplace Find an ENT Doctor Near You Noise and Hearing Protection Noise and Hearing Protection Patient ... it is. How can I tell if a noise is dangerous? People differ in their sensitivity to ...
9. Occupational noise management
NONE
2010-06-15
Occupational noise is a frequently encountered on-the-job health hazard. This guide presented the responsibilities and regulatory requirements related to business activities where noise above 80 decibels is present. The guide provided a definition of noise and discussed noise hazards, types of noise, and on-the-job noise exposure. A risk assessment to noise in the work environment was also discussed. A guide to a hearing conservation program was also included. The main purpose of a hearing conservation program is the prevention of noise induced hearing loss for employees exposed to occupational noise. The components of such a program were outlined, with particular reference to noise monitoring; noise exposure control; worker education and training; hearing (audiometric) testing; and annual program review and record keeping. It was concluded that in terms of record keeping, it can be very helpful to file noise exposure assessments, particularly personal exposure measurements, with hearing test records to facilitate for future reference. refs., appendices.
10. Aero-Acoustic Optimization of the Fans and Cooling Circuit on Sncf's X 72500 Railcar
CLEON, L.-M.; WILLAIME, A.
2000-03-01
This paper presents the results of studies concerning the fans on SNCF's X 72500 railcar with a view to reducing the level of ambient noise. The paper first describes the operation of an axial fan and then the main sources of noise generated by this type of fan. The interactions between acoustic emissions and mass output are then described to illustrate the advantages of an acoustic and pneumatic predictive device. Finally, a new design of axial wheel on the SNCF railcar is described which has reduced the acoustic emission by 10 db whilst still improving the initial ventilation performance.
11. Tinnitus pitch and acoustic trauma
Cahani, M.; Paul, G.; Shahar, A.
1983-01-01
Fifty-six subjects complaining of tinnitus underwent an audiometric test and a test for identifying the analogous pitch of their tinnitus. All of the subjects reported that they had been exposed to noise in the past. The subjects were divided into two groups on the basis of their audiometric test results. Group P was composed of subjects who showed a sensorineural hearing loss typical of acoustic trauma. Group N was composed of subjects whose hearing was within normal limits. The pitch of the tinnitus in group P was concentrated in the high-frequency range, whereas in group N tinnitus pitch values were distributed over the low and mid-audiometric frequency spectrum. It was deduced that different processes are involved in the generation of tinnitus in the two groups.
12. Occupant satisfaction with the acoustical environment : green office buildings before and after treatment
Hodgson, M. [British Columbia Univ., Vancouver, BC (Canada). School of Occupational and Environmental Hygiene, Acoustics and Noise Research Group
2009-07-01
Sustainable architecture is meant to preserve the environment and conserve natural resources, as well as provide an environment for the occupants that promotes wellbeing and productivity. Occupants generally claim that the acoustical environment is the least satisfactory aspect of green office buildings. They are dissatisfied with excessive noise and poor speech privacy. This paper reported on the results of 2 studies of the acoustical environments in green office buildings before and after acoustical-control measures were installed. Acoustical quality was evaluated by occupant-satisfaction surveys and acoustical-parameter measurements. The first study, which involved 6 green office buildings, showed that buildings designed to obtain LEED ratings are unlikely to have satisfactory acoustical environments. A naturally-ventilated, green university building with a poor acoustical environment was examined in the second study. The results of this study suggest that improving acoustical environments in green buildings requires good acoustical design, with input from an acoustical specialist from the beginning of the design process. The design should consider site selection and building orientation; external envelope and penetrations in it; building layout and internal partitions; HVAC systems; appropriate dimensioning of spaces; and the amount and location of sound absorbing treatments. The study also showed that a building's energy efficiency, lighting, ventilation, air-quality and acoustics are interconnected, and that no aspect can be successfully designed in isolation. It was concluded that optimized engineering-control measures can improve poor acoustical environments. 11 refs., 1 tab., 1 fig.
13. Characterization of an Acoustic Communication Channel with Pseudorandom Binary Sequences
Walree, P.A. van; Bertolotto, G.
2007-01-01
The joint European project "UUV Covert Acoustic Communications" explores methods for underwater communication at low signal-to-noise ratios. The first phase of the project focuses on characterization of the communication channel. Sea trials were conducted in two littoral environments in September 20
14. A Flexible Acoustic Sensor Network for Various Monitoring Applications
Basten, T.G.H.; Wessels, P.W.
2013-01-01
Acoustic monitoring using a sensor network is a powerful instrument to assess and manage complex noise situations. It can provide a basis to identify appropriate and cost effective measures, and to assess their effect by comparing before and after implementation. It can also be an instrument for com
15. Acoustic waves in shock tunnels and expansion tubes
Paull, A.; Stalker, R. J.
1992-01-01
It is shown that disturbances in shock and expansion tubes can be modelled as lateral acoustic waves. The ratio of sound speed across the driver-test gas interface is shown to govern the quantity of noise in the test gas. Frequency 'focusing' which is fundamental to centered unsteady expansions is discussed and displayed in centerline pitot pressure measurements.
16. Acoustic and vibration environments for laboratory experiments in space
1981-01-01
The basic parameters of random noise and vibration are described, and typical environments for the launch phase and orbital operations are presented. For the latter, both acoustically induced and structure-borne, thruster-included vibration are addressed, using data obtained during the Skylab and Titan programs.
17. Springer handbook of acoustics
2014-01-01
Acoustics, the science of sound, has developed into a broad interdisciplinary field encompassing the academic disciplines of physics, engineering, psychology, speech, audiology, music, architecture, physiology, neuroscience, and electronics. The Springer Handbook of Acoustics is also in his 2nd edition an unparalleled modern handbook reflecting this richly interdisciplinary nature edited by one of the acknowledged masters in the field, Thomas Rossing. Researchers and students benefit from the comprehensive contents. This new edition of the Handbook features over 11 revised and expanded chapters, new illustrations, and 2 new chapters covering microphone arrays and acoustic emission. Updated chapters contain the latest research and applications in, e.g. sound propagation in the atmosphere, nonlinear acoustics in fluids, building and concert hall acoustics, signal processing, psychoacoustics, computer music, animal bioacousics, sound intensity, modal acoustics as well as new chapters on microphone arrays an...
18. Noise evaluation of automotive A/C compressor
Sameh M. Metwally, Mohamed I. Khalil, Shawki A. Abouel-seoud
2011-05-01
Full Text Available Passenger compartment's interior noise and thermal performance are essential criteria for the driving comfort of vehicles. The air-conditioning system influences both field of comfort. It creates comfortable thermal conditions. On the other hand, the noise radiation of the air-condition system's components can be annoying. The blower, the air distribution ducts and the registers affect air rush noise. In some cases, the refrigerant flow creates hissing noise. Such noise has a great influence on vehicle acoustical comfort and on overall quality perception of a vehicle Therefore, the acoustic performance of air-condition compressors become more important for passenger comfort. At engine idling and at extreme temperatures the air-condition compressor can be audible as the significant sound source. However, the aim of this paper is to quantify air-borne noise characteristics of vehicle air-condition compressor. A simulated experimental model comprises a small wooden box with dimensions of 0.5 x 0.5 x 0.5 m represented the principle of hemi-anechoic room was designed and acoustic characteristics of the sound field inside the box were determined. The air-condition compressor characteristics parameters considered in this paper are fan position and electric motor speed. In addition, a single number of the air column natural frequency is calculated. The results indicate that significant information can be obtained in order to investigate the vehicle air-condition compressor and consequently improve the vehicle interior quietness.
19. Synergistic ototoxicity due to noise exposure and aminoglycoside antibiotics.
Li, Hongzhe; Steyger, Peter S
2009-01-01
Acoustic exposure to high intensity and/or prolonged noise causes temporary or permanent threshold shifts in auditory perception, reflected by reversible or irreversible damage in the cochlea. Aminoglycoside antibiotics, used for treating or preventing life-threatening bacterial infections, also induce cytotoxicity in the cochlea. Combined noise and aminoglycoside exposure, particularly in neonatal intensive care units, can lead to auditory threshold shifts greater than simple summation of the two insults. The synergistic toxicity of acoustic exposure and aminoglycoside antibiotics is not limited to simultaneous exposures. Prior acoustic insult which does not result in permanent threshold shifts potentiates aminoglycoside ototoxicity. In addition, exposure to subdamaging doses of aminoglycosides aggravates noise-induced cochlear damage. The mechanisms by which aminoglycosides cause auditory dysfunction are still being unraveled, but likely include the following: 1) penetration into the endolymphatic fluid of the scala media, 2) permeation of nonselective cation channels on the apical surface of hair cells, and 3) generation of toxic reactive oxygen species and interference with other cellular pathways. Here we discuss the effect of combined noise and aminoglycoside exposure to identify pivotal synergistic events that can potentiate ototoxicity, in addition to a current understanding of aminoglycoside trafficking within the cochlea. Preventing the ototoxic synergy of noise and aminoglycosides is best achieved by using non-ototoxic bactericidal drugs, and by attenuating perceived noise intensity when life-saving aminoglycoside therapy is required.
20. Sound attenuation using microelectromechanical systems fabricated acoustic metamaterials
Yunker, William N.; Stevens, Colin B.; Flowers, George T.; Dean, Robert N.
2013-01-01
Unlike traditional rotational gyroscopes, microelectromechanical systems (MEMS) gyroscopes use a vibrating proof mass rather than a rotational mass to sense changes in angular rate. They are also smaller and less expensive than traditional gyroscopes. MEMS gyroscopes are known to be susceptible to the effects of acoustic noise, in particular high frequency and high power acoustic noise. Most notably, this has been proven true in aerospace applications where the noise can reach levels in excess of 120 dB and the noise frequency can exceed 20 kHz. The typical resonant frequency for the proof mass of a MEMS gyroscope is between 3 and 20 kHz. High power, high frequency acoustic noise can disrupt the output signal of the gyroscope to the point that the output becomes unreliable. In recent years, considerable research has focused on the fascinating properties found in metamaterials. A metamaterial is an artificially fabricated device or structure that is engineered to produce desired material responses that can either mimic known behaviors or produce responses that do not occur naturally in materials found in nature. Acoustic metamaterials, in particular, have shown great promise in the field of sound attenuation. This paper proposes a method to mitigate the performance degradation of the MEMS gyroscope in the presence of high power, high frequency acoustic noise by using a new acoustic metamaterial in the form of a two-dimensional array of micromachined Helmholtz resonators. The Helmholtz resonators are fabricated in a silicon wafer using standard MEMS manufacturing techniques and are designed to attenuate sound at the resonant frequency of the gyroscope proof mass. The resonator arrays were diced from the silicon wafer in one inch squares and assembled into a box open on one end in a manner to attenuate sound on all sides of the gyroscope, and to seal the gyroscope inside the box. The resulting acoustic metamaterial device was evaluated in an acoustic chamber and was | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6576298475265503, "perplexity": 3343.784616236576}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-30/segments/1500549426951.85/warc/CC-MAIN-20170727022134-20170727042134-00489.warc.gz"} |
https://www.tiredpixel.com/2013/index-4.html | # walking all combinations of infinite lists
#### Introduction
Some programming languages supply an interleave method for combining elements from infinite lists. The usual pattern for this is cycling through the set of lists, taking successive elements. When combination as a tuple is required, however, the problem becomes more complex, because of the need to ensure that every combination of elements is visited. Walking all combinations of finite lists is straightforward; it is possible to chain lists together and use an increment-and-carry method. This approach is unsuitable for infinite lists, as the first list to be incremented would never carry. It is thus necessary to weave the lists together without getting trapped in infinity.
We consider only indexed, random-access lists (that is, lists where the cost of fetching an element by its index is the same regardless of the index). For example, a list of the Fibonacci Sequence generated using a recursive method would not be suitable (regardless of the method of recursion), but the Fibonacci Sequence generated by Binet’s Formula would be acceptable. We also wish to be able to subdivide the walk of combinations in a parallelisable and state-recoverable manner (that is, we wish to be able to describe ranges of the walk in such a way that the walk can be started or continued from that point, without overlapping with unwanted combinations); thus, we do not consider methods employing nested interleaves. We show that is is possible to satisfy these properties and walk all combinations of infinite lists in a dense manner.
#### Reduction to 2 lists
We call our walk $W$ and represent the first combination walked as $W_1$, which will represent some address $(A_x, B_y)$ where $x, y$ are the indexes to be determined. The walked combinations are thus $W_1, W_2, \ldots$. Note $x, y \in \mathbb{N}$ (from which we always exclude $0$). We name the elements of List $L$ $[L_1, L_2, \ldots]$. Note that we use unity-indexing throughout.
It is sufficient to walk all combinations of only two infinite lists. That is because multiple lists can be combined in a binary tree, satisfying the required properties. For example, consider Lists $A$, $B$, $C$. Suppose it is possible to walk combinations of $A$ and $B$; then it is possible to combine these lists as List $AB$, where $AB_1$ addresses the first combination from Lists $A$ and $B$ (similar to how we use $W$ to represent our overall walk). We then walk Lists $AB$ and $C$. (This means we walk lists at different speeds for more than 2 lists, because of the binary tree. However, the walk is still dense and satisfies the required properties.)
With lists combined in this way, we consider only walking all combinations of 2 infinite lists.
#### Method for 2 lists
We claim the following satisfies the required properties for walking all combinations of 2 infinite Lists X and Y, defining the formulas thusly for subsequent convenience:
\begin{array}{rcl} m(n) & = & \left \lceil \frac{1 + \sqrt{1 + 8n}}{2} \right \rceil \newline x(n) & = & n - \frac{(m(n) - 1)(m(n) - 2)}{2} \newline y(n) & = & m(n) - x(n) \newline & where \newline n & \in & \mathbb{N} \end{array}
Using these formulas, we define the required function:
\begin{array}{rcl} f & : & \mathbb{N} \to \mathbb{Z}^2 \newline n & \mapsto & \left( x(n), y(n) \right) \end{array}
We show that the image of $f$ is in fact $\mathbb{N}^2$, that $f$ is both injective and surjective, and hence that $f$ is bijective $\mathbb{N} \to \mathbb{N}^2$. This is so we can walk $\mathbb{N}$, using $x(n)$ as the index in List X, and $y(n)$ as the index in List Y.
##### Image of $f$
$\forall n \in \mathbb{N}$, $m(n) \in \mathbb{Z}$. Thus, $x(n) \in \mathbb{Z}$ since the fraction is odd times even. Thus, $y(n) \in \mathbb{Z}$. We seek to show that $x(n), y(n) \geq 1$, meaning $x(n), y(n) \in \mathbb{N}$ and thus the image of $f$ is $\mathbb{N}^2$.
Let us define the subsets of $\mathbb{N}$:
\begin{array}{rcl} S_t & := & \left\lbrace n \in \mathbb{N} : \frac{(t - 1)(t - 2)}{2} < n \leq \frac{t(t - 1)}{2} \right\rbrace \newline & for \newline t & \in & \mathbb{N} \setminus \lbrace 1 \rbrace \end{array}
For example, $S_2 = \lbrace 1 \rbrace$, $S_3 = \lbrace 2, 3 \rbrace$, $S_4 = \lbrace 4, 5, 6 \rbrace$, etc. We note $S_2 \cup S_3 \cup S_4 \cup \dots = \mathbb{N}$, thus $S_t$ partitions $\mathbb{N}$. We observe that by construction, each $S_t$ contains precisely one triangle number.
We consider what happens when we put a triangle number into $m$:
\begin{array}{rcl} m\left( \frac{t(t - 1)}{2} \right) & = & \left \lceil \frac{1 + \sqrt{1 + 8\left( \frac{t(t - 1)}{2} \right)}}{2} \right \rceil \newline & = & \left \lceil \frac{1 + \sqrt{4\left( t - \frac{1}{2} \right)^2}}{2} \right \rceil \newline & = & \left \lceil \frac{1 + 2 \left( t - \frac{1}{2} \right)}{2} \right \rceil \newline & = & \lceil t \rceil \newline & = & t \end{array}
We observe that $m$ is non-strict increasing, since $\forall n \in \mathbb{N}$:
\begin{array}{rcl} \frac{1 + \sqrt{1 + 8(n + 1)}}{2} & > & \frac{1 + \sqrt{1 + 8n}}{2} \end{array}
and since $a < b \implies a < \lceil b \rceil \implies \lceil a \rceil \leq \lceil b \rceil$
\begin{array}{rcl} \left \lceil \frac{1 + \sqrt{1 + 8(n + 1)}}{2} \right \rceil & \geq & \left \lceil \frac{1 + \sqrt{1 + 8n}}{2} \right \rceil \newline & \implies \newline m(n+1) & \geq & m(n) \end{array}
We next take an arbitrary $s \in S_t$, and consider $m(s)$. By the construction of $S_t$:
\begin{array}{rcl} \frac{(t - 1)(t - 2)}{2} & < s & \leq \frac{t(t - 1)}{2} \newline & \implies \newline m \left( \frac{(t - 1)(t - 2)}{2} \right) & \leq m(s) & \leq m \left( \frac{t(t - 1)}{2} \right) \end{array}
since $m$ non-strict increasing, thus $t - 1 \leq m(s) \leq t$. But $m(s) \in \mathbb{Z}$, so $m(s) \in \lbrace t - 1, t \rbrace$.
We seek to exclude $m(s) = t - 1$. Let us imagine such a value is fine, and reach a contradiction.
\begin{array}{rcl} m(s) & = & \left \lceil \frac{1 + \sqrt{1 + 8s}}{2} \right \rceil \newline & \iff \newline m(s) - 1 & < \frac{1 + \sqrt{1 + 8s}}{2} & \leq m(s) \newline & \implies \newline t - 2 & < \frac{1 + \sqrt{1 + 8s}}{2} & \leq t - 1 \newline & \implies \newline 2(t - 2) - 1 & < \sqrt{1 + 8s} & \leq 2(t - 1) - 1 \newline & \implies \newline (2t - 5)^2 & < 1 + 8s & \leq (2t - 3)^2 \newline & \implies \newline \frac{(2t - 5)^2 - 1}{8} & < s & \leq \frac{(2t - 3)^2 - 1}{8} \newline & \implies \newline \frac{1}{2}t^2 - \frac{5}{2}t + 3 & < s & \leq \frac{1}{2}t^2 - \frac{3}{2}t + 1 \newline & \implies \newline \frac{(t - 2)(t - 3)}{2} & < s & \leq \frac{(t - 1)(t - 2)}{2} \end{array}
But by construction of $S_t$, $\frac{(t - 1)(t - 2)}{2} < s \leq \frac{t(t - 1)}{2}$, thus $s < s$ and we reach a contradiction.
Thus, $m(s) \in \lbrace t \rbrace$ so $m(s) = t$. Thus, for any $s \in S_t$, $m(s) = t$. This means that by partitioning $\mathbb{N}$ in this manner, we can consider each $S_t$ within which $m(s)$ is constant and the ceiling function no longer makes us anxious.
We now show that $x(n), y(n) \geq 1$. Instead of trying to show this directly, we show that it is true within every $S_t$. But since that partitions $\mathbb{N}$, it yields the required result.
Take $s \in S_t$. By construction of $S_t$:
\begin{array}{rcl} s & > & \frac{(t - 1)(t - 2)}{2} \newline & \implies \newline s - \frac{(t - 1)(t - 2)}{2} & > & 0 \newline & \implies \newline s - \frac{(t - 1)(t - 2)}{2} & \geq & 1 \newline & \implies \newline x(s) & \geq & 1 \end{array}
meaning every element in $S_t$ is strict positive, so $x(n) \geq 1 \forall n \in \mathbb{N}$.
Similarly, take $s \in S_t$. By construction of $S_t$:
\begin{array}{rcl} s & \leq & \frac{t(t - 1)}{2} \newline & = & \left( \frac{t(t - 1)}{2} + 1 \right) - 1 \newline & = & \left( \frac{(t - 1)(t - 2)}{2} + t \right) - 1 \newline & \leq & \frac{(m(s) - 1)(m(s) - 2)}{2} + m(s) - 1 \newline & \implies \newline 1 & \leq & m(s) - s + \frac{(m(s) - 1)(m(s) - 2)}{2} \newline & = & y(s) \end{array}
meaning every element in $S_t$ is strict positive, so $y(n) \geq 1 \forall n \in \mathbb{N}$.
Since we already know $f : \mathbb{N} \to \mathbb{Z}^2$, we observe that the image is in fact $\mathbb{N}^2$, so we can redefine $f : \mathbb{N} \to \mathbb{N}^2$ and say that the image and the codomain are the same.
##### Injectivity of $f$
Choose $(x_1, y_1) \in \mathbb{N}^2$ according to $f$ for some $n_1 \in \mathbb{N}$ such that:
\begin{array}{rcl} m_1 & = & \left \lceil \frac{1 + \sqrt{1 + 8n_1}}{2} \right \rceil \newline x_1 & = & n_1 - \frac{(m_1 - 1)(m_1 - 2)}{2} \newline y_1 & = & m_1 - x_1 \end{array}
Choose $(x_2, y_2) \in \mathbb{N}^2$ in a similar manner for some $n_2 \in \mathbb{N}$. Suppose $(x_1, y_1) = (x_2, y_2)$. Then $x_1 = x_2$ and $y_1 = y_2$.
Substituting, $y_2 = m_1 - x_2$. Since $y_2 = m_2 - x_2$, $m_1 = m_2$.
Also substituting, $x_1 = n_2 - \frac{(m_2 - 1)(m_2 - 2)}{2} = n_2 - \frac{(m_1 - 1)(m_1 - 2)}{2}$. Since $x_1 = n_1 - \frac{(m_1 - 1)(m_1 - 2)}{2}$, $n_1 = n_2$.
Thus $f$ is injective.
##### Surjectivity of $f$
Choose arbitrary $(x_1, y_1) \in \mathbb{N}^2$. We seek $n_1 \in \mathbb{N}$ such that $f$ is satisfied; that is:
\begin{array}{rcl} m(n_1) & = & \left \lceil \frac{1 + \sqrt{1 + 8n_1}}{2} \right \rceil \newline x_1 = x(n_1) & = & n_1 - \frac{(m(n_1) - 1)(m(n_1) - 2)}{2} \newline y_1 = y(n_1) & = & m(n_1) - x(n_1) \end{array}
It might seem straightforward to substitute and solve for $n_1$ explicitly, then calculate $m(n_1)$ explicitly, then show that $x(n_1) = x_1$ and $y(n_1) = y_1$. In this form, however, dancing with the ceiling function is tricksy. Instead, we view the problem as a system of constraints and rewrite it into a simpler form, finding $n_1$ along the way.
\begin{array}{rcl} m(n_1) & = & \left \lceil \frac{1 + \sqrt{1 + 8n_1}}{2} \right \rceil \newline x_1 & = & n_1 - \frac{(m(n_1) - 1)(m(n_1) - 2)}{2} \newline y_1 & = & m(n_1) - x_1 \end{array}
and substituting $m(n_1)$ throughout:
\begin{array}{rcl} x_1 + y_1 & = & \left \lceil \frac{1 + \sqrt{1 + 8n_1}}{2} \right \rceil \newline x_1 & = & n_1 - \frac{(x_1 + y_1 - 1)(x_1 + y_1 - 2)}{2} \end{array}
and rewriting the ceiling function as an inequality and rearranging:
\begin{array}{lcl} x_1 + y_1 - 1 < \frac{1 + \sqrt{1 + 8n_1}}{2} \leq x_1 + y_1 \newline n_1 = x_1 + \frac{(x_1 + y_1 - 1)(x_1 + y_1 - 2)}{2} \end{array}
Considering the inequality:
\begin{array}{lcl} x_1 + y_1 - 1 < \frac{1 + \sqrt{1 + 8n_1}}{2} \leq x_1 + y_1 \newline \implies 2(x_1 + y_1) - 3 < \sqrt{1 + 8n_1} \leq 2(x_1 + y_1) - 1 \newline \implies \left\lbrack 2(x_1 + y_1) - 3 \right\rbrack^2 < 1 + 8n_1 \leq \left\lbrack 2(x_1 + y_1) - 1 \right\rbrack^2 \newline \implies \frac{\left\lbrack 2(x_1 + y_1) - 3 \right\rbrack^2 - 1}{8} < n_1 \leq \frac{\left\lbrack 2(x_1 + y_1) - 1 \right\rbrack^2 - 1}{8} \newline \implies \frac{ 4(x_1 + y_1)^2 - 12(x_1 + y_1) + 8}{8} < n_1 \leq \frac{ 4(x_1 + y_1)^2 - 4(x_1 + y_1) }{8} \newline \implies \frac{1}{2}(x_1 + y_1)^2 - \frac{3}{2}(x_1 + y_1) + 1 < n_1 \leq \frac{1}{2}(x_1 + y_1)^2 - \frac{1}{2}(x_1 + y_1) \end{array}
Considering the equality:
\begin{array}{rcl} n_1 & = & x_1 + \frac{(x_1 + y_1 - 1)(x_1 + y_1 - 2)}{2} \newline & = & x_1 + \frac{1}{2}(x_1 + y_1)^2 - \frac{3}{2}(x_1 + y_1) + 1 \end{array}
Thus we can rewrite the system as:
\begin{array}{lcl} \frac{1}{2}(x_1 + y_1)^2 - \frac{3}{2}(x_1 + y_1) + 1 < n_1 \leq \frac{1}{2}(x_1 + y_1)^2 - \frac{1}{2}(x_1 + y_1) \newline n_1 = x_1 + \frac{1}{2}(x_1 + y_1)^2 - \frac{3}{2}(x_1 + y_1) + 1 \end{array}
and multiplying by $2$ and substituting $n_1$:
\begin{array}{lcl} (x_1 + y_1)^2 - 3(x_1 + y_1) + 2 < 2x_1 + (x_1 + y_1)^2 - 3(x_1 + y_1) + 2 \leq (x_1 + y_1)^2 - (x_1 + y_1) \end{array}
We now split the inequality. The LHS simplifies to $0 < x_1 \implies 1 \leq x_1$ which we know to be true. The RHS simplifies to $x_1 - (x_1 + y_1) + 1 \leq 0 \implies -y_1 \leq -1 \implies y_1 \geq 1$ which we know to be true.
So our candidate solution to the system, which must be unique if so, is:
\begin{array}{rcl} n_1 = x_1 + \frac{(x_1 + y_1 - 1)(x_1 + y_1 - 2)}{2} \end{array}
which was fairly clear at the beginning, but we have shown it satisfies all the constraints including the ceiling. Clearly, $n_1 \in \mathbb{Z}$ since the fraction is even times odd. But $x_1, y_1 \geq 1 \implies x_1 + y_1 \geq 2 \implies n_1 \geq 1$, so $n_1 \in \mathbb{N}$.
Thus, we have found $n_1 \in \mathbb{N}$ which satisfies the constraints and this $n_1 \mapsto (x_1, y_1)$, which was an arbitrary choice in $\mathbb{N}^2$. Thus $f$ is surjective.
#### Conclusion
Since $f : \mathbb{N} \to \mathbb{N}^2$ is both injective and surjective, it is bijective. We have also found explicit ways of converting between $\mathbb{N}$ and $\mathbb{N}^2$ in either direction. This $f$ satisfies the properties we required for walking all combinations of infinite Lists X and Y. We make ourselves anxious about the holes and mistakes in our argument, hope they are not too serious, and finish off the coffee. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.990602433681488, "perplexity": 685.1330282280028}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-34/segments/1502886106996.2/warc/CC-MAIN-20170820223702-20170821003702-00036.warc.gz"} |
https://www.physicsforums.com/threads/how-do-they-measure-quark-masses-quark-charges.834356/ | # How do they measure quark masses? Quark charges?
1. Sep 24, 2015
### H_Hernandez
Hello,
So, I know quarks are confined in baryons. In a proton, there are "3" quarks, but the sum of their masses is not the mass of the proton. This implies a major fraction of the proton mass comes from interactions. My question is, how then do they measure quark u and d masses? And simmilarily, their charges?
2. Sep 24, 2015
### mathman
Google "quark mass measurement". You will get lots of hits, including old entries in this forum.
3. Sep 24, 2015
### Staff: Admin
4. Sep 24, 2015
### Avodyne
It is possible to compute how the masses of quark-containing particles (such as the proton, neutron, and pion, collectively known as hadrons) depend on the quark masses. Then, the observed values of the hadron masses can be used to determine the quark masses.
For complete details, see
http://pdg.lbl.gov/2012/reviews/rpp2012-rev-quark-masses.pdf
This is a technical document, intended for experts, but I think it's pretty readable nonetheless, and gives a good picture of what physicists actually do to figure these things out. One key point is that, because quarks are confined, their "mass" does not have as clear and simple a definition as it does for unconfined particles such as the electron.
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Similar Discussions: How do they measure quark masses? Quark charges? | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9650061130523682, "perplexity": 1637.5792847676782}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-43/segments/1508187825057.91/warc/CC-MAIN-20171022022540-20171022042540-00053.warc.gz"} |
http://mathhelpforum.com/algebra/179169-mixture-problem-help.html | # Math Help - Mixture Problem Help
1. ## Mixture Problem Help
Im having trouble understanding mixture problems. (and all the other ones like distance,work rate)
So my question is...
Victor is making orange juice. He has one pitcher that contains 2 quarts of 50% concentrate, and another pitcher that contains 4 quarts of 20% concentrate. If he combines the two pitchers, how many quarts of water must he add so that he ends up with a mixture containing 25%?
A) 0.5
B)1
C) 1.2
D) 2.4
2. Originally Posted by seals123
Im having trouble understanding mixture problems. (and all the other ones like distance,work rate)
So my question is...
Victor is making orange juice. He has one pitcher that contains 2 quarts of 50% concentrate, and another pitcher that contains 4 quarts of 20% concentrate. If he combines the two pitchers, how many quarts of water must he add so that he ends up with a mixture containing 25%?
A) 0.5
B)1
C) 1.2
D) 2.4
let x = quarts of added water
2(.5) + 4(.2) + x(0) = (6+x)(.25)
3. Thanks!
I wasn't putting x for water. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8074417114257812, "perplexity": 4758.16691307931}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-23/segments/1404776435465.20/warc/CC-MAIN-20140707234035-00029-ip-10-180-212-248.ec2.internal.warc.gz"} |
http://www.mathportal.org/calculators/complex-numbers-calculator/complex-unary-operations-calculator.php | Math Calculators, Lessons and Formulas
It is time to solve your math problem
You are here:
# Calculators :: Complex numbers :: Operations with one complex number
This calculator extracts the square root, calculate the modulus, finds inverse, finds conjugate and transform complex number to polar form. The calculator will generate a detailed explanation for each operation.
## Operations with one complex number
This calculator will find absolute value, inverse, conjugate or polar for a given complex number.
You can enter either integers (10), decimal numbers(10.12) or FRACTIONS(10/3). Important: The form will NOT let you enter wrong characters (like *, (, ), y, p, ...) How to input??
0 1 2 3 4 5 6 7 8 9 - / . del
conjugate (default) modulus inverse roots polar form
Show me an explanation.
## Formulas for conjugate, modulus, inverse, polar form and roots
### Conjugate
The conjugate of the complex number z = a + bi is:
Example 1:
Example 2:
Example 3:
### Modulus (absolute value)
The absolute value of the complex number z = a + bi is:
Example 1:
Example 2:
Example 3:
### Inverse
The inverse of the complex number z = a + bi is:
Example 1: | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.967217743396759, "perplexity": 3463.4439119463177}, "config": {"markdown_headings": true, "markdown_code": false, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-18/segments/1461861700245.92/warc/CC-MAIN-20160428164140-00182-ip-10-239-7-51.ec2.internal.warc.gz"} |
https://timhagmann.com/html/ac209a/HW8.html | # CS 109A/AC 209A/STAT 121A Data Science: Homework 8¶
Harvard University
Fall 2016
Instructors: W. Pan, P. Protopapas, K. Rader
Due Date: Wednesday, November 16th, 2016 at 11:59pm
Clear namespace
In [1]:
# Clear namespace
for name in dir():
if not name.startswith('_'):
del globals()[name]
Import libraries
In [2]:
# Data manipulation
import numpy as np
import pandas as pd
# Ploting
import matplotlib
import matplotlib.pyplot as plt
%matplotlib inline
# Scientific computing
import scipy as sp
# Machine Learning
from sklearn import linear_model
from sklearn.decomposition import PCA
from sklearn.cross_validation import KFold
from sklearn import svm
from sklearn.linear_model import LogisticRegression
from sklearn.grid_search import GridSearchCV
from sklearn.cross_validation import StratifiedShuffleSplit
from sklearn.metrics import f1_score
from sklearn import tree
[Hagmann, Tim]
[CS 109a]
[-]
## Problem 1: Image Processing Revisited¶
In this problem we revisit applications of classification, with the purpose of comparing the performance of support vector classifiers with other classifiers we have learned. We'll begin with the aeriel vegetation detection problem from Homework #7.
The data is contained in dataset_1.txt and dataset_2.txt (you are encouraged to use the datasets from Homework #7 as well). The first two columns of the data contains the latitude and longitudes of randomly sampled locations in the satellite image, and the last column contains a label indicating whether the location contains vegetation (1 denotes the presence of vegetation and 0 denotes otherwise). The task is to, again, identify the vegetation regions in the image.
## Functions (necessary for the following calculations)¶
In [3]:
#-------- plot_decision_boundary
# A function that visualizes the data and the decision boundaries
# Input:
# x (predictors)
# y (labels)
# model (classifier)
# poly_flag (fits quadratic model if true, otherwise linear)
# title (title for plot)
# ax (a set of axes to plot on)
# Returns:
# ax (axes with data and decision boundaries)
def plot_decision_boundary(x, y, model, title, ax, bounds=(0, 1), poly_flag=False):
# Plot data
ax.scatter(x[y == 1, 0], x[y == 1, 1], c='darkgreen', alpha=0.6, s=60, edgecolors="None")
ax.scatter(x[y == 0, 0], x[y == 0, 1], c='black', alpha=0.6, s=60, edgecolors="None")
# Create mesh
interval = np.arange(bounds[0], bounds[1], 0.01)
n = np.size(interval)
x1, x2 = np.meshgrid(interval, interval)
x1 = x1.reshape(-1, 1)
x2 = x2.reshape(-1, 1)
xx = np.concatenate((x1, x2), axis=1)
# Predict on mesh points
if(poly_flag):
yy = model.predict(xx)
yy = yy.reshape((n, n))
# Plot decision surface
x1 = x1.reshape(n, n)
x2 = x2.reshape(n, n)
ax.contourf(x1, x2, yy, alpha=0.2, cmap='Greens')
# Label axes, set title
ax.set_title(title)
ax.set_xlabel('Latitude')
ax.set_ylabel('Longitude')
ax.grid()
return ax
In [4]:
#-------- fit_and_plot_svm_for_c
# Fit and plot SVM model for value of 'C', overlayed on a scatter plot of data
# (fit on train set and evaluate on test set)
#
# Input:
# x_train (array of train predictors)
# y_train (array of train responses)#
# x_test (array of test predictors)
# y_test (array of test responses)
# bounds (tuple of bounds for plotting)
# C (value for parameter C)
# ax (axes to plot on)
def fit_and_plot_svm_for_c(x_train, y_train, x_test, y_test, C, ax, bounds=(0, 1)):
model = svm.SVC(C=C, kernel='linear')
model.fit(x_train, y_train)
# Train and test error
tr_acc = model.score(x_train, y_train)
ts_acc = model.score(x_test, y_test)
# Plot decision boundary
plot_decision_boundary(x_train, y_train, model, \
'C = ' + str(C)\
+ ', ACC (Train) = ' + str(tr_acc)\
+ ', ACC (Test) = ' + str(ts_acc), ax, bounds)
# Plot support vectors
sv_indices = model.support_
ax.scatter(x_train[sv_indices, 0], x_train[sv_indices, 1], color='red', alpha=0.15, s=200)
return ax
In [5]:
#-------- kernel_switcher
# A Function to varying the kernels
#
# Input:
# df_train (array of train predictors)
# df_test (array of test predictors)
def kernel_switcher(df_train, df_test):
# Select x-variables
x_train = df_train[:, 0:-1]
x_test = df_test[:, 0:-1]
# Select yvariables
y_train = df_train[:, -1]
y_test = df_test[:, -1]
fig, ax = plt.subplots(1, 4, figsize = (30, 7))
kernel_list = ['linear', 'poly', 'rbf', 'sigmoid']
# Fit models
for i, kernel in enumerate(kernel_list):
# SVM
svm_fit = svm.SVC(C=10000, kernel=kernel)
svm_fit.fit(x_train, y_train)
sv_indices = svm_fit.support_
ax[i].scatter(x_train[sv_indices, 0], x_train[sv_indices, 1], color='red', alpha=0.15, s=100)
# Train and test error
tr_acc = svm_fit.score(x_train, y_train)
ts_acc = svm_fit.score(x_test, y_test)
# Plot boundaries
ax[i] = plot_decision_boundary(x_train, y_train, svm_fit,
str(kernel) + ' Kernel'+', ACC (Train) = ' + str(tr_acc)\
+ ', ACC (Test) = ' + str(ts_acc), ax[i])
In [6]:
#-------- fit_and_plot_dt
# Build a decision tree and plot the data
# Input:
# df_train (array of train predictors)
# df_test (array of test predictors)
# depth (depth of tree)
# ax (axis)
def fit_and_plot_dt(df_train, df_test, depth, ax):
x_train = df_train[:, 0:-1]
x_test = df_test[:, 0:-1]
y_train = df_train[:, -1]
y_test = df_test[:, -1]
# Tree
dt = tree.DecisionTreeClassifier(max_depth = depth)
dt.fit(x_train, y_train)
# Train and test error
tr_acc = dt.score(x_train, y_train)
ts_acc = dt.score(x_test, y_test)
# Plotting
ax = plot_tree_boundary(x_train, y_train, dt, 'Depth = ' + str(depth)\
+ ', ACC (Train) = ' + str(tr_acc)\
+ ', ACC (Test) = ' + str(ts_acc), ax)
return ax
In [7]:
#-------- plot_tree_boundary
# A function that visualizes the data and the decision boundaries
# Input:
# x (predictors)
# y (labels)
# model (the classifier you want to visualize)
# title (title for plot)
# ax (a set of axes to plot on)
# Returns:
# ax (axes with data and decision boundaries)
def plot_tree_boundary(x, y, model, title, ax):
# Plotting
ax.scatter(x[y==1, 0], x[y==1, 1], c='darkgreen', alpha=0.6, s=60, edgecolors="None")
ax.scatter(x[y==0, 0], x[y==0, 1], c='black', alpha=0.6, s=60, edgecolors="None")
# Preparation
interval = np.arange(0,1, 0.01)
n = np.size(interval)
x1, x2 = np.meshgrid(interval, interval)
x1 = x1.reshape(-1, 1)
x2 = x2.reshape(-1, 1)
xx = np.concatenate((x1, x2), axis=1)
yy = model.predict(xx)
yy = yy.reshape((n, n))
# Plot surface
x1 = x1.reshape(n, n)
x2 = x2.reshape(n, n)
ax.contourf(x1, x2, yy, alpha=0.1, cmap='Greens')
# Astetics
ax.set_title(title)
ax.set_xlabel('Latitude')
ax.set_ylabel('Longitude')
ax.grid()
return ax
### Step 1: Load the data and explore¶
Let's load the two datasets and visualize them.
In [8]:
# Load dataset_1
# Plot data
fig, ax = plt.subplots(1, 2, figsize = (20, 6))
#Plot dataset 1
x = data_1.values[:, :-1]
y = data_1.values[:, -1]
ax[0].scatter(x[y==0, 0], x[y==0, 1], label='non vegetation', c='black', alpha=0.6, s=60, edgecolors="None")
ax[0].scatter(x[y==1, 0], x[y==1, 1], label='vegetation', c='darkgreen', alpha=0.6, s=60, edgecolors="None")
ax[0].set_xlabel('Longitude')
ax[0].set_ylabel('Latitude')
ax[0].set_title('Dataset 1')
ax[0].legend(loc='best', scatterpoints = 1)
ax[0].grid()
#Plot dataset 2
x = data_2.values[:, :-1]
y = data_2.values[:, -1]
ax[1].scatter(x[y==0, 0], x[y==0, 1], label='non vegetation', c='black', alpha=0.6, s=60, edgecolors="None")
ax[1].scatter(x[y==1, 0], x[y==1, 1], label='vegetation', c='darkgreen', alpha=0.6, s=60, edgecolors="None")
ax[1].set_xlabel('Longitude')
ax[1].set_ylabel('Latitude')
ax[1].set_title('Dataset 2')
ax[1].legend(loc='best', scatterpoints = 1)
ax[1].grid()
plt.show()
It looks like the classes in dataset 1 is well separated, while the classes in dataset 2 is not. That means that while dataset 1 has no overlapp of the points dataset 2 has some.
In [9]:
# Load dataset_1
x = data_1.values[:, :-1]
y = data_1.values[:, -1]
# Fit SVM model with C = 1000, linear kernel
model = svm.SVC(C=1000, kernel='linear')
model.fit(x, y)
# Plot decision boundary
fig, ax = plt.subplots(1, 2, figsize = (20, 6))
ax[0] = plot_decision_boundary(x, y, model, 'dataset_1 (fit with entire data)', ax[0])
# Highlight the support vectors
sv_indices = model.support_ # retrieve the support vector indices
ax[0].scatter(x[sv_indices, 0], x[sv_indices, 1], color='red', alpha=0.15, s=200) # draw circles around SVs
# Isolate only support vectors and their labels
x_svs = x[sv_indices, :]
y_svs = y[sv_indices]
model.fit(x_svs, y_svs)
# Plot decision boundary with only support vectors
ax[1] = plot_decision_boundary(x_svs, y_svs, model, 'dataset_1 (refit with only SVs)', ax[1])
# Highlight the support vectors
ax[1].scatter(x_svs[:, 0], x_svs[:, 1], color='red', alpha=0.15, s=200) # draw circles around SVs
plt.show()
The above plots show, that the support vectors are the points used for calculating the hyperplane decision boundary. Removing the other points (done in plot two) has no effect on the decision boundary.
In [10]:
# Load dataset_1
x = data_2.values[:, :-1]
y = data_2.values[:, -1]
# Fit SVM model with C = 1000, linear kernel
model = svm.SVC(C=1000, kernel='linear')
model.fit(x, y)
# Plot decision boundary
fig, ax = plt.subplots(1, 2, figsize = (20, 6))
ax[0] = plot_decision_boundary(x, y, model, 'dataset_2 (fit with entire data)', ax[0])
sv_indices = model.support_ # retrieve the support vector indices
ax[0].scatter(x[sv_indices, 0], x[sv_indices, 1], color='red', alpha=0.15, s=200) # draw circles around SVs
# Isolate only support vectors and their labels
x_svs = x[sv_indices, :]
y_svs = y[sv_indices]
model.fit(x_svs, y_svs)
# Plot decision boundary with only support vectors
ax[1] = plot_decision_boundary(x_svs, y_svs, model, 'dataset_2 (refit with only SVs)', ax[1])
# Highlight the support vectors
ax[1].scatter(x_svs[:, 0], x_svs[:, 1], color='red', alpha=0.15, s=200) # draw circles around SVs
plt.show()
It appears that in both cases, the decision boundary of an SVM is completely determined by a subset of data points - the support vectors. In Dataset 1, it's possible to find a subset of points from the two classes that are well separated, SVM chooses the subset in which the classes are maximally separated (the margin between points from different classes is maximized). In Dataset 2 it is not possible. Any decision boundary will have some errors (a mix of classes on either side). That means it the selection of the support vectors are very important to optimize the model.
## Step 2: Play with values of the parameters of the model¶
In defining our support vector classifier, the parameter C and kernel have to be specified.
The parameter C is to tune the bounds of the sum of errors for the classification. That means it controls how much the of a violation of the hyperplane margin the model tolerates. It can be seen as a budget for how much the margin can be violated.
The value of C affects how many support vectors are chosen an also the variance of the model. The more support vectors are chosen the lower the variance. The bigger the C value the wider the margin and the model tollerates more violations of the margin.
This can be demonstrated with the simulation below:
In [11]:
# Load train data
x_train = data_train[:, 0:-1]
y_train = data_train[:, -1]
x_test = data_test[:, 0:-1]
y_test = data_test[:, -1]
# Fit and plot for different 'C' values
fig, ax = plt.subplots(1, 3, figsize = (15, 3))
ax[0] = fit_and_plot_svm_for_c(x_train, y_train, x_test, y_test, 0.1, ax[0], (-10, 10))
ax[1] = fit_and_plot_svm_for_c(x_train, y_train, x_test, y_test, 1, ax[1])
ax[2] = fit_and_plot_svm_for_c(x_train, y_train, x_test, y_test, 100, ax[2])
plt.tight_layout()
For dataset_2, any linear decision boundary would have some errors. In this case, SVM chooses a decision boundary by trading-off the errors for margin (i.e. balancing minimizing error with maximizing margin). It appears that the parameter $C$ controls the trade-off.
Increasing $C$ lays more emphasis on accuracy and less emphasis on the margin of separation. As a result, the model tends to overfit the train set, and perform poorly on the test set.
For $C=0.01$, the model clearly underfits the train set. For $C=100$, the model overfits the train set. For $C=1$, the fitted model misclassifies a point in the upper left corner (which could have othwerwise been classified correctly by a linear model), and achieves higher margin.
## Step 3: Push your analysis further¶
### 1. How does SVM compare with the other classifiers we know¶
As a first step we're fitting a decision tree with different dept levels to the available datasets.
### CART fitted on dataset 1¶
In [12]:
# Load train data
Plotting CART with different depth levels. The chosen levels are 1 split, 2 splits, 4 splits and 10 splits.
In [13]:
# Plot for dataset_1
fig, ax = plt.subplots(nrows=2, ncols=2, figsize=(20, 10))
# Plot data and decision boundary
ax[0, 0] = fit_and_plot_dt(train_1, test_1, 1, ax[0, 0])
ax[0, 1] = fit_and_plot_dt(train_1, test_1, 2, ax[0, 1])
ax[1, 0] = fit_and_plot_dt(train_1, test_1, 4, ax[1, 0])
ax[1, 1] = fit_and_plot_dt(train_1, test_1, 10, ax[1, 1])
plt.tight_layout()
plt.show()
As can be seen above, the depth levels doesn't matter. The points are always perfectly split in the dataset 1.
### CART fitted on dataset 2¶
In [14]:
# Load train data
Plotting CART with different depth levels. The chosen levels are 1 split, 2 splits, 4 splits and 10 splits.
In [15]:
# Plot for dataset_2
fig, ax = plt.subplots(nrows=2, ncols=2, figsize=(20, 10))
# Plot data and decision boundary
ax[0, 0] = fit_and_plot_dt(train_2, test_2, 1, ax[0, 0])
ax[0, 1] = fit_and_plot_dt(train_2, test_2, 2, ax[0, 1])
ax[1, 0] = fit_and_plot_dt(train_2, test_2, 4, ax[1, 0])
ax[1, 1] = fit_and_plot_dt(train_2, test_2, 10, ax[1, 1])
plt.tight_layout()
plt.show()
The above plots show, that the depth of the tree matters for the decision boundary. The further down the split the closer the decision boundary to the training points.
## 2. Changing the shape of the decision boundarys¶
It looks like the only decision boundaries SVM draws, so far, are lines. This is pretty limiting. Is there any way for us to change the shape of the decision boundary (how did we get logistic regression to draw curvy boundaries)?
This can be done by transforming the feature space in a non linear fashion (polynomial). In order to do this kernels can be used. Using kernels means transforming the feature vector to fitting a support vector in a high-dimensional space.
### Kernel switching on dataset 1¶
Using 4 different kernels for the SVM. Those are a linear kernel, a polynomial kernel, a rbf kernel and a sigmoid kernel
In [16]:
# Plot 4 different kernels
kernel_switcher(train_1, test_1)
### Kernel switching on dataset 2¶
In [17]:
# Plot 4 different kernels
kernel_switcher(train_2, test_2)
## 3. Which model is better for remote senseing¶
In this lab, we've only explored SVM. How does SVM compare with other classifiers in terms of addressing the challenges of remote sensing for land cover analysis?
Dataset 1
The CART classification on dataset 1 achieves a maximum test accuracy of 0.89 with a depth level of 1 compared to an accuracy of 1.0 with a linear SV and rbf kernel. The SVM performs in this setting better.
Dataset 2
On the dataset 2 the CART classifier performs the best with a depth level of 4 where it achieves an accuracy of 0.825. This in contrast to 0.7625 of the polynomial kernel of the svm. The CART tree performs for this data better.
## 4. Comparing the results¶
Compare the result of using support vector classifiers to perform classification against results obtained from other models you have learned. Which model is more appropriate for the general task of vegetation detection in aerial images (do not restrict yourself to which model performs better on just these two datasets)?
The above results show, that when modeling vegetation it can't always be assumed that the modeled areas occure in distinct cluster. The problem with SVM's is, that they are only able to model a single decision boundary between vegetation and non-vegetation. The CART approach on the other hand can also model smaller patches of land inbetween the clusters. This is done with the depth of the tree.
## 5. What is the most appropriate model¶
Which model is more appropriate for other types of image processing (hand-writting digit classification for example)
In order to address the topic of hand-writting digit classification I would argue that SVM's are more appropriate than using CART. The reason for this is, that SVM's are spare, which means that they only require a very small subset of the handwritting points. That means that SVM's are not affected by large datasets and less prone to the course of dimensionalty, i.e., they are more able to handly high dimensionality problems.
## 6. Drawbacks of SVM's¶
Are there any obvious draw backs to support vector classifiers as we have presented them to you? What might be some intuitive ways to address these draw backs?
Classical SVM's have a linear kernel and can only cut the hyperplane in a linear fashion. This was for example addressed by Burgess (1998): "Perhaps the biggest limitation of the support vector approach lies in choice of the kernel." This can be addressed by using different kernels that are able to transform the hyperplane into complex non linear decision boundaries.
A further drawback is presented by categorical variables. In order to solve this issue, the categorical variables can be recoded with dummy variables.
Last but not least a further drawback is the algorithmic complexity and extensive memory requirements of the required quadratic programming in large-scale tasks. This problem can nowadays be easierd solved trough the usage of cloud computing options like AWS, Azure or others.
## Problem 2 (Optional): Classification Competition¶
I took part in the Harvard Data Science Competition competition. My rank is 6th out of 97. The link to my profile is the following:
https://www.kaggle.com/timhagmann
## Challenge Problem: Meta Learning¶
In the problem, you are provided with 10 different previously trained prediction models for a spam classification task. The task is to investigate how can one combine these models into a single meta classification model (without retraining the individual models) that performs better than each of the individual ones?
## Functions (necessary for the following calculations)¶
In [18]:
#-------- find_mode
# Generate for the test set a mode prediction.
# Input:
# row (define the row)
def find_mode(row_index):
counts = np.unique(row_index, return_counts=True)[1]
if (len(counts) == 2 and counts[0] == counts[1]):
if np.random.random() >0.5:
return counts[0]
return counts[1]
return np.argmax(counts)
The data for this problem is provided in the files dataset_5_train.txt and dataset_5_test.txt. Each row of these files is an email described by 57 attributes, and the last column is 1 if the email is spam, and 0 otherwise.
The prediction models are provided in the file models.npy and can be loaded into an array by executing:
models = np.load('models.npy')
In [19]:
# Load models from the npy file
# Load train and test dataframe
Extract the x and y variables
In [20]:
# Extract x and y variables
x_train = train_5[:, 0:-1]
y_train = train_5[:, -1]
x_test = test_5[:, 0:-1]
y_test = test_5[:, -1]
## Make predictions¶
As before, you can make predictions using the $i^\text{th}$ using:
model[i].predict(x_test)
and score the model using:
model[i].score(x_test, y_test)
In [21]:
# Get a n x 10 prediction matrix of the training and testing testing set of the model
pred_train = np.zeros((x_train.shape[0], len(models)))
pred_test = np.zeros((x_test.shape[0], len(models)))
for i in range(len(models)):
pred_train[:, i] = models[i].predict(x_train)
pred_test[:, i] = models[i].predict(x_test)
## Create a baseline model¶
The baseline for this task is a simple combination strategy that takes a majority vote from the individual prediction models.
In [22]:
# Find mode vectories with apply
majority_vote = np.apply_along_axis(find_mode, axis=1, arr=pred_test)
baseline_accuracy = np.mean(majority_vote == y_test)
Printing the accuracy score:
In [23]:
print 'Majority vote for the baseline accuracy:', round(baseline_accuracy * 100, 2), '%'
Majority vote for the baseline accuracy: 77.87 %
The majority vote baseline ensemble model reaches a accouracy of 77.87% that should be beaten by the following ensemble model.
## Create an ensemble model¶
There are three very popular methods for combining predictions from different models. Those are:
• Bagging: Building multiple models (typically of the same type) from different subsamples of the training dataset.
• Boosting: Building multiple models (typically of the same type) each of which learns to fix the prediction errors of a prior model in the chain.
• Stacking: Building multiple models (typically of differing types) and supervisor model that learns how to best combine the predictions of the primary models.
The here used approach falls into the category of stacking. A good approach to do this is to use a GLM or logistic regression on the predictions from the 10 models. The resulting response is the y variable that indicates if an email is classified as spam or not.
Building a glm on the training data leads to the coefficients for each of the predictors that gives "weights" to the prediction generadet by the seperated models.
In [24]:
# Logistic ensemble model
log_model = LogisticRegression().fit(pred_train, y_train)
test_y_pred = log_model.predict(pred_test)
log_model_accuracy = np.mean(test_y_pred == y_test)
Printing the accuracy score:
In [25]:
print 'Ensemble model accuracy score:', round(log_model_accuracy * 100, 2), '%'
Ensemble model accuracy score: 89.6 %
The combined ensemble model build with a GLM gives an accuracy score of 89.6% which is better that the baseline score. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.24522079527378082, "perplexity": 8579.60716437381}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-31/segments/1627046154466.61/warc/CC-MAIN-20210803155731-20210803185731-00325.warc.gz"} |
https://www.physicsforums.com/threads/centripetal-acceleration.293149/ | # Centripetal Acceleration
1. Feb 17, 2009
### lauriecherie
1. The problem statement, all variables and given/known data
What would Earth's rotation period have to be for objects on the equator to have a centripetal acceleration equal to 9.8 m/s^2?
____ min
2. Relevant equations
Centripetal acceleration is equal to velocity * (2PI/T),
where T is the period in seconds.
3. The attempt at a solution
I set centripetal acceleration equal to 9.8m/s^2 and solved for T. Then I took T and divided it by 60 so I could get the answer in minutes. I came out with 4.97 min which Webassign says is incorrect. Any ideas?
Last edited: Feb 17, 2009
2. Feb 17, 2009
### LowlyPion
One way to look at it is that if the object is not to fall into the center then calculate the orbit about a mass of Earth at 1 earth radius.
So what is the period of such an orbit?
V2/R = GM/R2 = ω2R
ω2 = GM/R3 = (2π /T)2
T = 2π*(R3/GM)1/2
3. Feb 17, 2009
### lauriecherie
What does GM stand for?
4. Feb 17, 2009
### LowlyPion
That's sometimes written as μ which is the standard gravitational parameter for earth.
It is the product of earth's mass and the Universal Gravitational constant. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9562206268310547, "perplexity": 1631.565458982692}, "config": {"markdown_headings": true, "markdown_code": false, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-13/segments/1552912202781.33/warc/CC-MAIN-20190323080959-20190323102959-00185.warc.gz"} |
http://socialhacker.com/posts/page/2/ | This HOWTO describes a couple things that you can do to secure your SSH server on a Linux machine (Ubuntu, RedHat, Suse...).
This is useful because there are script kiddies all around trying to break into computers. And I imagine that botnets writers will take more interest in Linux as it's market share increases.
The pattern that I have seen is of many many requests from the same IP address trying to guess users and passwords. Most of the requests are trying to guess the root password.
There are a couple things we can do to slow these attackers. The most obvious is to configure ssh to only allow logins from a couple select users. And to disallow remote login by the root user. We can also use IPTables to only allow a limited number of connections per minute. And finaly, we can move the SSH server to a different port on the machine. I don't know if this actually causes the attackers any pause however. They may just be trying all of the open ports.
There are more complex solutions to the problem. Port knocking or log parsing come to mind. But I've opted for the simplest solution that doesn't impact usability in my case.
The use of IPTables to limit repeated connections is based on work by Kevin van Zonneveld. You can see his approach on his blog
## What is IPTables
IPTables is part of the kernels network stack (I think). It is a user configurable state machine that can be used to filter packets as they are received, before they are forwarded or before they are transmitted.
Our configuration will drop incoming packets that meet a specific set of rules.
## SSHD configuration
The file /etc/ssh/sshd_config is used to configure the ssh server on your linux machine. The changes I made to mine were to change "Port 22" to "Port xxxx" and to add "AllowUsers yyyy zzzz wwww" where xxxx is the new port you want SSH to listen to. yyyy, zzzz and wwww are the users that you want to have remove access. I also made sure that the line "PermitRootLogin no" existed and was not commented out.
## SSH configuration
If you have changed the port that sshd listens to then you will probably want to configure your ssh clients on any machine that you would like to access your server from. In your home directory on each of these machines you should find "~/.ssh/". In that directory you can create a config file. It's just called config. Put the following in that file. Again, xxxx is the new port that your ssh server is listening to.
Host your.server.name
Port xxxx
## Network scripts
In Ubuntu there are directories that contain scripts to run when an interface comes up or goes down. These are convenient places to put the IPTables commands needed to drop attackers packets. The directory for scripts to run when a network interface comes up is /etc/network/if-up.d. And the directory for scripts to run when a network interface goes down is /etc/network/if-down.d. We will create one file in the if-up.d directory and a symlink in the if-down.d directory. We do this to consolidate the logic in a single location. We can use the MODE variable to determine if the interface is coming up or going down.
In /etc/network/if-up.d/ssh-protection put the following.
#!/bin/bash
SSH_IFACE="eth1"
SSH_PORT=xxxx # This should be the port you've moved your ssh server to, or 22 if you haven't moved it.
SSH_PERIOD=60
SSH_COUNT=8
#
# Only add the rules to the interface that SSH is actually listening on.
#
if [ "$IFACE" != "$SSH_IFACE" ]; then
exit 0
fi
case "$MODE" in start) IPTABLES_ACTION="-A" ;; stop) IPTABLES_ACTION="-D" ;; esac /sbin/iptables$IPTABLES_ACTION INPUT \
-i $IFACE \ -p tcp \ --dport$SSH_PORT \
-m state \
--state NEW \
-m recent \
--set \
--name SSH
/sbin/iptables $IPTABLES_ACTION INPUT \ -i$IFACE \
-p tcp \
--dport $SSH_PORT \ -m state \ --state NEW \ -m recent \ --update \ --seconds$SSH_PERIOD \
--hitcount $SSH_COUNT \ --rttl \ --name SSH \ -j DROP This file needs to be executable by root. You can use the following command line to make it so. chmod u+x /etc/network/if-up.d/ssh-protection And in /etc/network/if-down.d create a symlink to the ssh-protection file in if-up.d using the following command line. This command line assumes you're in the if-down.d directory. ln -s ../if-up.d/ssh-protection Comment This HOWTO describes the steps required to setup your RedHat (well any Linux distro) firewall to forward the port used by gtk-gnutella to a machine on your internal network. This is useful because it allows your gtk-gnutella client to behave in a non firewalled mode and thus more of the gnutella network is available to you. In particular, other machines that are behind firewalls that can handle push requests will become available to you. ## What is Port Forwarding? Port forwarding is a feature of the IPTables system. It allows one computer to forward connections made to it so that another computer can actually process the request. If you want a very simple metaphor you can think of it as mail forwarding. Each computer has a number of addresses called ports, and IPTables allows (among other things) connections to these ports to be sent to another computer. The most common use of port forwarding that I am aware of is allowing servers to run on machines that would normally be hidden behind a firewall. ## Firewall script I am going to assume that you are using the default firewall script that comes with RedHat or whatever distribution you are running. My system is currently running RedHat 8.0 (heh, not anymore). And I am using a firewall script called rc.firewall-2.4. You should be able to find it in your /etc/rc.d directory. If you don't find it it may be that I had to install it and just don't remember. :) You can search for rc.firewall-2.4 on Google and find many copies. ## Setup My goal was to make gtk-gnutella work in a non-firewalled mode from within my firewalled LAN. To do this people suggested a line of the form: $IPTABLES -t nat -I PREROUTING -p tcp -i $EXTIF --dport 6346 -j DNAT --to 192.168.0.2:6346 Where$IPTABLES is the iptables executable, $EXTIF is the external ethernet interface (I use two ethernet cards in my firewall), port 6346 is the gtk-gnutella port and 192.168.0.2 is the machine on my internal network on which I wished to run gtk-gnutella. With the rc.firewall-2.4 script this doesn't quite work. The reason is that by default any connection that would open a new session from the outside world is dropped. This is done with the line: $IPTABLES -P FORWARD DROP
The solution is to add a rule into the FORWARD chain that causes connections from the outside world to port 6346 to not be dropped, but instead to be accepted. Then the PREROUTING rule above will be encountered and the connection will be forwarded to the internal machine as desired. The line to accomplish this is:
$IPTABLES -A FORWARD -i$EXTIF -o $INTIF -p tcp --dport 6346 -j ACCEPT I placed this right before the line: $IPTABLES -A FORWARD -j LOG
I did this because this line will will add a rule that causes all rules added after it to not be checked.
Comment
All right, now that we have some blogs up. We will want to enable SSL/TLS security, also known as https. The reason you want this may be obvious to some. But to spell it out for you, if you don’t use https to connect to your administrative pages in Movable Type while you’re sipping on your latte, then everyone else that’s on that wireless network can see you type your password in, plain as day. And by “can”, I mean there is nothing preventing them from watching your traffic. Most likely, no one is, but you never know.
There are a couple of complications that we will need to work through though. Firstly, SSL and name based virtual hosting are mostly incompatible. And secondly, unless you get a Certificate Authority, such as Verisign, to sign your SSL key you and your security conscious visitors will be presented with an ugly message from the browser saying that your site is trying to identify itself with an invalid security certificate.
First you need to enable SSL in your Apache configuration. In the Apache2 configuration for Ubuntu these files are located in /etc/apache2. You’ll need to make sure that your ports.conf file contains something like the following:
Listen 80
<IfModule mod_ssl.c>
Listen 443
</IfModule>
This causes Apache to listen on port 443 for connections as well as port 80. Port 443 is the https port. And your conf.d/namevirtualhosts file should look something like:
NameVirtualHost *:80
NameVirtualHost *:443
This tells Apache to look up virtual hosts by name for traffic coming in on either port. Next you need to make sure that your conf.d/ssl_certificate file looks something like:
SSLCertificateFile /etc/apache2/ssl/serverwide.crt
SSLCertificateKeyFile /etc/apache2/ssl/serverwide.key
You can see that I’ve called my certificate and key files serverwide to make it obvious that they are used by all domains served by this server. It is very important that these files have their permissions set so that only root can read them. You’ll also need to make symlinks from the ssl.conf and ssl.load files in your mods-available directory to your mods-enabled directory.
Now we’re ready to generate and sign our key and certificate. Once you have generated the certificate you can inspect it’s contents with this command.
openssl x509 -in serverwide.crt -noout -text
To generate a key use the following command. You will be asked for a pass phrase. It is important that you remember this pass phrase or your key will be lost to you forever. Or at least until computers are powerful enough to brute force crack your key.
openssl genrsa -des3 -rand /dev/urandom -out serverwide.key 1024
Once you have a key you can create and sign a certificate with the following command. You will be asked for the pass phrase you entered above. This is because the key is protected by that pass phrase and can’t be used without it. This certificate will be valid for one year.
openssl req -config server.config -new -key serverwide.key -out serverwide.crt -x509 -days 365
Most of the options we need to pass to OpenSSL to create and sign the certificate can be passed in a configuration file. The command line above assumes the configuration file is called server.config. Below is an example server.config file, the main lines of interest are in the alt_names section. The alt_names section is where you can put all of the virtually hosted domains on your server. The browser will look for a match with any of those domains when the server passes it the certificate we have just generated. I also found that subjectAltName had to be in both the v3_req and v3_ca sections.
[ req ]
default_bits = 1024
default_md = sha1
distinguished_name = req_distinguished_name
prompt = no
req_extensions = v3_req
x509_extensions = v3_ca
[ req_distinguished_name ]
countryName = <country code>
stateOrProvinceName = <state>
localityName = <city>
organizationName = <whatever, could be your name>
organizationalUnitName = <again, whatever>
commonName = www.domain1.com
[ v3_req ]
basicConstraints = CA:FALSE
keyUsage = nonRepudiation, digitalSignature, keyEncipherment
subjectAltName = @alt_names
[ v3_ca ]
subjectAltName = @alt_names
[ alt_names ]
DNS.1 = www.domain1.com
DNS.2 = www.domain2.com
DNS.3 = www.domain3.com
The key that we have generated will have a pass phrase associated with it (the one you entered when you generated the key). This pass phrase will need to be entered every time you restart your apache server. There are ways of removing this extra security, but if you want to do that I’ll let you look that one up elsewhere. For me with a server running on a UPS, I reboot or restart apache a couple of times a year at most. The added security is well woth it. If your server get’s compromised, and it will eventually, then your security key will be coppied. And that is as they say, a bad thing.
And finally, in your site configuration file, probably in /etc/apache2/sites-available, you will need to add the following:
<VirtualHost *:443>
ServerName www.domain1.com
ServerAlias domain1.com *.domain1.com
DocumentRoot /var/www/domain1
SSLEngine On
</VirtualHost>
This is the Virtual host configuration file for your secured site. You’ll want to add any additional configurations to it from your normal *:80 configuration section.
Comment
It was a lot harder than I anticipated to get Movable Type to run from a single global install on all of my virtually hosted domains. So in the spirit of sharing, here’s how I did it.
First, install movable type into a directory at the root of your web servers directory structure. I put mine in /var/www/shared/. The resulting directory structure contained:
/var/www/shared/cgi-bin/mt
This directory contains pretty much everything in the Movable Type tarball.
/var/www/shared/mt-static
This directory is the mt-static directory from the Movable Type tarball. I moved it out to the top level of the shared directory because I have Apache configured to not serve documents from the cgi-bin directory.
/var/www/shared/conf
This directory will contain the configuration files for all of the sites you will be virtually hosting.
Next configure apache for each of your virtually hosted domains. I assume you already have virtual hosting up and running. The configuration file for socialhacker.com looks like this:
<VirtualHost *:80>
ServerName www.socialhacker.com
ServerAlias socialhacker.com *.socialhacker.com
DocumentRoot /var/www/socialhacker
SetEnv MT_HOME /var/www/shared/cgi-bin/mt
SetEnv MT_CONFIG /var/www/shared/conf/socialhacker.cgi
ScriptAlias /cgi-bin/ /var/www/shared/cgi-bin/
Alias /mt-static/ /var/www/shared/mt-static/
</VirtualHost>
The important bits here are how you set up the alias’ and the environment variables. And all of this is covered in this article.
Finally, you need to create a configuration file in the shared/conf directry for your site. I did this by hand, which you’ll need to do as well since Movable Type won’t set most of these options in the configuration file it generates.
CGIPath /cgi-bin/mt/
StaticWebPath /mt-static/
StaticFilePath /var/www/shared/mt-static/
PluginPath /var/www/shared/cgi-bin/mt/plugins/
TemplatePath /var/www/shared/cgi-bin/mt/tmpl/
WeblogTemplatesPath /var/www/shared/cgi-bin/mt/default_templates/
ObjectDriver DBI::mysql | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.1905287504196167, "perplexity": 3236.780925710374}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-21/segments/1620243988775.25/warc/CC-MAIN-20210507060253-20210507090253-00305.warc.gz"} |
http://voloda.bazilisek.net/2014/12/visual-studio-2012-debugger-does-not-break-after-attaching-to-csharp-dotnet-process/ | # Visual Studio 2012 debugger does not break after attaching to C#/.NET process
· Read in about 2 min · (233 words) ·
I had from time to time issue debug C#/.NET applications in Visual Studio 2012 after attaching Visual Studio 2012 debugger to a process.
Symptoms were that the debugger attached to the process but neither ‘Break All’ worked. The same applied for any preset breakpoint.
For some time I thought that Visual Studio installation for somehow corrupted on my system but since I was always able to workaround it via Debug.Assert() or Debugger.Break() calls put directly into code I had never motivation to really look for a solution nor reinstall the Visual Studio.
Today I really wanted to attach to a process to see what is going on inside and the issue happened again.
After a bit of playing I realized that in the case that debugger works after attaching correctly the ‘Attach to Process’ Visual Studio dialog looks like this (see ‘Attach to’ field):
For my process it didn’t work this time and ‘Attach to Process’ dialog looked like this (again see ‘Attach to’ field):
Apparently Visual Studio in some cases does not properly detect the type of the process and does not use correct debugger settings.
In order to solve my issue I finally found the ‘Select…’ button following ‘Attach to’ field where you can disable automatic detection of the process type and manually select a different one.
After selecting ‘Manager (v4.5, 4.0)’ and attaching debugger to process again everything worked well.
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Category | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.35940438508987427, "perplexity": 4030.1272282116693}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-39/segments/1537267155561.35/warc/CC-MAIN-20180918150229-20180918170229-00134.warc.gz"} |
https://physics.stackexchange.com/questions/176760/problem-on-einstein-de-haas-experiment?noredirect=1 | # Problem on Einstein - de Haas experiment
I am a Physics student (4th year) and I'm trying to study the Einstein - de Haas effect in laboratory. That is what I got: a suspended Iron cylinder with about 5 cm height and a radius of 0.8 cm is put inside a solenoid which can create a magnetic field of 0.2 mT; we use a Titanium fiber of 0.05 mm radius to hold up the cylinder.
Now where is the problem? Well we expect that when we turn on the current and so create the magnetic field through the solenoid, the cylinder would rotate just a bit, for example 2 degrees because that is what is written in the Einstein - de Haas article... but not! We got rotation of 70° and more (to measure such a great angle we used a camera which records the piece while rotating)! Measuring the initial angular velocity with a computer, and substituting it in the formula:
$$I \omega = -(2m/e) M$$
Where $I$ is the moment of inertia, $\omega$ is the angular velocity and $M$ is the magnetization of our material (which we can obtain), we get a value so far from $(2m/e)\simeq10^{-11}rad / s \cdot T$ in fact we got something like $10^{-5}$. I know that we should obtain something like the double of $(2m/e)$ but we are neither close to it!
In conclusion: should we force ourselves to have an angle of $1°\sim5°$ and then (and only then) measure the angular velocity because this effect is measurable only with little oscillation, or we got something strange, which means that we should change the system because something is interfering? Obviously we have isolated as we can the system from air currents and ground vibrations.
If you need more information about what we are using in the experiment, just say it and I will provide them. Thanks!
New information (about the comment of HolgerFielder): the wire diameter I've already given: Titanium 0.1 mm; if you mean the diameter of the solenoid's wire, that is 2 mm almost. Coil diameter = 4 cm. Number of loops = 200. Current $\simeq$ 1.5 Ampère. From these values and using this formula for magnetic field of a solenoid with radius r and with length l (in its "central axis"):
$$B = \mu _{0} (N/l) i \cdot l/(\sqrt(l^{2} + 4 r^{2}))$$
one can obtain $B \simeq 2.2$ mT which is close to the value that we measure with the Gaussmeter (0.2 mT as I mentioned before, in the top of the question). | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9468093514442444, "perplexity": 178.41015460699703}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-43/segments/1570986673250.23/warc/CC-MAIN-20191017073050-20191017100550-00299.warc.gz"} |
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