I am just wondering what are the methods which can hide all the transactions and also able to validate transactions in an block chain?

Question: I am new to block chain and was looking at how block chain work mainly proof of stake based . They check validity by going through all the transactions which is something concerning as everyone can see the transactions. So what are ways to hide all transactions and also make everyone able to check validity of new block.
This question is not only for block chain relm but also for cryptography.
Answer:
So what are ways to hide all transactions

In the blockchain used by Bitcoin it is not ever possible to hide transaction details because the integrity of the whole system depends on those being public.
However the sensitive parts of those details are mostly Bitcoin-addresses and amounts. There is a privacy issue if observers can infer information by comparing use of the same address across multiple transactions.
This is why Bitcoin (for example) is often described as not anonymous but as psedonymous. You can't see people's names in transaction data but you can see the Bitcoin-addresses.
Generally people hide their identity by

never re-using Bitcoin-addresses and by
using coin tumblers.

This makes it very very difficult for third-party observers to associate a transaction with a specific person.
Answer: Generally, what you want to hide is the correspondence between outputs and inputs. So, for example, say you send me one unit of currency and then I send one unit of currency to someone else. What we don't need to hide:

You had one unit of currency to send.
You wanted to send that one unit of currency somewhere.
You no longer have the one unit of currency you had in step 1.
I had one unit of currency.
I want to send that one unit of currency somewhere.
My transfer of one unit of currency will prevent me from sending one unit of currency that I could previous send.

What we don't want to reveal:

The one unit of currency that I transferred is the same unit of currency that you transferred.

There are various cryptographic techniques that can be used to reveal the six things we do need to reveal without revealing the one thing we don't want to reveal. Zcash, for example, does this by having a person prove that they rendered unusable one output that they previously could have used without revealing which output they've rendered unusable. So if you send me one unit of zcash and I send one unit of zcash somewhere, it is not possible to connect the unit you send me with the unit I sent. All you know is that I previously had one unit of zcash I could send and now I do not, but it can be any unit of zcash send previously.


How do I build a city without industrial zones?

Question: I remember when I was playing this last year I built a city with absolutely zero industrial zones, and no need for them. How do I do this?
Answer: According to this thread you can absolutely play without building industrial zones. I think the key to it is as stated (bold is my emphasis):

"You can build fully functional cities where all the goods are simply imported from outside the map, having all your peeps working in offices"

You'll just have to make up for any of the industrial demand elsewhere basically.
Someone else commented:

"My current city is at 132K strong and with almost constant residential and commercial demand, with near to 0 industrial demand. Around 80% of all industrial buildings are already abandoned and the city keeps growing nevertheless."

So it seems you can either opt out of it and try to import to meet any demand, or there may just be minimal demand. If your sims are educated and there are less of a workforce for industrial jobs those buildings will be abandoned but that won't necessarily stop your city from growing.
Comment: Thanks, I will give it a go. Just gotta make sure my city access is perfect!


Domain Access - restrict content for only authenticated users (and keep domain specific settings)

Question: I have a site using domain with multiple subdomains.
I want to display some of the particular domains. I can do this with the "Publish to *" field in the domain access options. How do I also restrict access to some content types so that only authenticated users can access these content types and also work with domain access?
I had the module content_access installed to prevent ANONYMOUS USERS from viewing specific content types but this was causing problems with domain as it would write to the node_access table realm=all & view=1 for all content types. This meant that all domains could get access to the content even though the check boxes were set to one specific domain. I think the node_access permission logic is connected with OR.
Any guidance would be appreciated!
Answer: Actually I found the issue was with the content_access module. It was overriding the settings for the domain access.
Once this was turned of domain was able to operate as designed with just the 'publish to ...' settings.


What was the first band considered to be punk?

Question: Punk is a very distinctive sub genre of rock with it's own very interesting sound, look, and persona. Which band was the first band that was classified as a punk band and start this trend?
Comment: [The start of punk](https://books.google.com/books?id=SpGmxL8tTAEC&pg=PA6&lpg=PA6&dq=may+1971+creem+looney+tunes&source=bl&ots=2f6mLfnobN&sig=-HfoiamrvL4MYqEwKrwnM1n9MFE&hl=en&sa=X&ei=wOslVciOHYLdsATl7ICwAw&ved=0CEIQ6AEwCQ#v=onepage&q=may%201971%20creem%20looney%20tunes&f=false) was the band who brought us the song '96 Tears'.  Bet you didn't expect that.  ;o)
Comment: Iggy Pop(?) could be mentioned in addition to the answer here.
Comment: The Sex Pistols would be my answer, but this is really subjective regardless of any one person's opinion.
Comment: again, subjective, but I've always gone for the [Standells with "Dirty Water"](https://en.wikipedia.org/wiki/The_Standells)
Answer: I would actually disagree that punk is a distinctive subgenre. Punk is a pretty broad variety of sounds unified by philosophy and some aesthetics.
Punk as a label for a music and culture is generally considered born in late 70's London. Some people would actually say that punk traces back as much to Malcolm McLaren, who created the Sex Pistols and was otherwise influential in the culture, as much as to any band. No doubt devotees of UK punk could name precursors.
But many would argue that Punk was born in early 70's New York, with groups like the Ramones, and arguably, even the Velvet Underground. I've heard Detroit's MC5 labeled as punk, and they started in the 60's. And some people would include the 60's garage rock scene as punk, which is how you get claims like in Johnny Bones' comment. The Wikipedia Timeline of
   Punk labels that period "protopunk."
Sorry, you'll rarely get a straight "who was the first" answer out of me (in any genre.)
Comment: Yup.  You'll get the same answer to "What was the first metal song".  And you'll see some of the same bands mentioned in the PROTO phase (MC5 in particular.) Excellent Non-Answer.
Answer: To expand on the New York roots of punk, folk singer Jeffrey Lewis has a great little song about the origins of punk that goes all the way back to the 50's.
Check out Jeff's history of punk here: https://www.youtube.com/watch?v=fnmrAthgi8g
I would personally argue that most of what he is talking about in the song is what was going on in music that lead up to Punk (what Joe calls protopunk in the post above), he does however mention that in 1971 Lester Bangs was the first person to use the word "Punk" in print to describe enthusiastic teenage rock music, and in 1972 Lenny K coined the term "Punk Rock" in the liner notes of a Garage Rock compilation called 'Nuggets'.
As far as what we know now to be the spikey hair, torn clothes template look of punk rock as made famous by the Sex Pistols comes directly from musician Richard Hell. Malcolm Mclaren (the manager of the Sex Pistols) credits himself for taking Richard Hell's look back to England in 1974(ish) to feed to the London youth via his clothing shop "Sex", where his wife, fashion designer Vivienne Westwood recreated the Richard Hell look with the addition of bondage gear, tartan patterns and chrome studs that we recognize today as the quintessential punk look.
Answer: Punk covers such a broad range of sounds, styles, and subgenres that I don't really think this has a definitive answer.
Punk in New York, London and Australia all sort of happened independently around about the same time in the early 70's. I do believe the Damned were the first punk band to release a single amongst the 70's English bands, as were The Saints in Australia.
But then as mentioned above you had the proto punk bands of the 60's such as The Stooges and The MC5 who were definitely punk in sound and attitude.
The Lenny Kaye Nuggets also mentioned above, and I do believe it was ? and the Mysterians who did 96 Tears.
Go back to the fifties and you had the original rockers who all embodied the "Spirit of Punk" Jerry Lee Lewis, Eddie Cochran, Gene Vincent, early Elvis.
The blues of Robert Johnson?
There really is no definitive answer to What band was the first to be considered punk? Everyone's opinions will vary greatly.


Activation of Swedish personummer

Question: I was a resident of Sweden but moved after living there for 2 years. Can I move back with my minor son who holds a Swedish passport? Can I reactivate my Swedish personummer and get a duplicate card?
Comment: There was another question like this recently. The residence permit is cancelled if you leave Sweden for more than a year, apparently. You should be able to call skatteverket on the telephone and find out.
Comment: There is probably not much you can do from India. If you need help understanding the documents (ie validity) you can post scans (with your name etc blacked out).
Comment: Thanku for responding.  As I don't have the card,  the lifetime residence permit is stamped on the passport that I used then.  I only know the personummer so I am trying to find out if I can still get a duplicate ID card.
Comment: Some say that the ID validity is lifetime. So I guess it is not valid if the residence permit is not.  Thankyou for your help
Comment: No the cards are normally valid for five years I think.
Comment: The ID number is likely still valid. That is, if you moved to Sweden, you would use the same number. But, as @TomasBy said, your residence permit is unlikely to be valid.
Answer:
Can I reactivate my Swedish personummer and get a duplicate card?

When you get your Swedish personal number, it is valid for life.
Therefore, if you can get a visa or other form of permit to live in Sweden again, you can just resume using the personal number that you were assigned in the past.
However, whether you can simply move to Sweden with your son is another question — probably not, but do post the question separately.
Comment: While the number *itself* applies to you for life, that doesn't mean the rights that people tend to associate with the number (but actually come from registration) do. What matters is whether you are registered in Sweden (folkbokförd). And if a non-EEA citizen, have residence permit etc.
Answer: It's unclear exactly what you're asking about.
If you lived in Sweden before and were folkbokförd (registered in the population register) then you will have received a personnummer. You keep that number for life. However, you do not keep the status of being folkbokförd for life, which is the part that actually matters. If you leave Sweden, you cease to be folkbokförd as living in Sweden and lose the rights associated with that. If you return to Sweden and later get folkbokförd again they will reopen your record and reuse the number. I'm not sure what happens to Swedish ID cards (not the National kind citizens can get from police) if you leave, I suspect they may cancel it but I'm not sure, and in any case it's only 400 SEK to get a new one.
None of that has any relevance to whether you have the right to move back to Sweden or get a residence permit, though, if that's what you're asking. If you had a residence permit in Sweden and left, it is no longer valid. If you are an EEA or Swiss national, or moving together as a family member with one, you are allowed to move back to Sweden without needing a permit though.
If your son holds Swedish citizenship then, in theory, you can move back to Sweden with them as their family member under EEA rules, but that only works if you're moving from an EEA country, which I'm guessing (from your other posts) you're not. Your best bet is probably to apply to Migrationsverket for a new residence permit based on your son's citizenship?

Activation of Swedish personummer


How was the historical definition of the meter used in practice?

Question: The meter was initially defined as $10^{-7}$ times the distance of the north pole to the equator. How exactly was this definition used to fabricate the actual meter sticks from which the standard meter bar -which subsequently actually determined how long one meter was- was selected?
Answer: Once the definition in terms of the length of the meridian was accepted, the French sent several expeditions to measure the meridian. On the basis of these expeditions, the reference meter (a stick of a special alloy, which has very little thermal expansion) was made and kept
under controlled conditions. Later, when more precise measurements of Earth were made, it was decided to change the definition, and use the standard reference stick
instead of the length of the meridian.
See, for example this article
Comment: @Marc: That's a purely technical problem. Some stick was necessary in the process of measuring the meridian, to set a unit of length in the triangulation process. After the measuring, from this stick a new one can be manufactued to match the given part of the meridian.
Comment: Given this numerical value of the length of the meridian, how did they actually fabricate a stick with the length of a ten-millionth?
Comment: Copypaste from Wikipedia entry 'Toise':
 In 1735 two geodetic standards were calibrated against the Toise of Châtelet. One of them, the Toise of Peru was used for the Spanish-French Geodesic Mission. In 1766 the Toise of Peru became the official standard of length in France and was renamed Toise of the Academy (French: Toise de l'Académie). In 1799, after the remeasurement of the Paris meridian arc (French: Méridienne de France) between Dunkirk and Barcelona by Delambre and Mechain, the metre was defined as 3 pieds (feet) and 11.296 lignes (lines) of the Toise of the Academy.[2]


If a web site shows me what my password was changed to, is it stored as plain text?

Question: I just changed the password on a school-related web site.  After completing the change successfully, the next page showed what the password was changed to.  Can I conclude from this that the password is not being stored only as a hash?
Comment: This is also worrysome for a different reason: Showing the password on screen makes it vulnerable to [shoulder surfing](http://en.wikipedia.org/wiki/Shoulder_surfing_%28computer_security%29). When the website is school-related, it is to be expected that people use it in a classroom with many other people present who are able to see their screen. This makes this even more negligent.
Comment: Showing it on screen not only raises shoulder surfing concerns, but history concerns as well.  If the browser history is not properly managed (read: cleared constantly) then someone could sit down at a PC, search for the password change page in the history folder, and come up with a bunch of passwords in one swing.
Comment: It might never be hashed; it might instead be encrypted/decrypted. Without seeing the server-side code (which could be any level of sophistication), there's no way we can know.
Comment: It might be wiser to differentiate between "stored in a way it can be retrieved" (be it plain text or reversible encryption) and "stored in an unretrievable way" (one way hashing).
Answer: No, you cannot conclude that.
The password can be hashed on the server-side only, which implies that the password is sent in plain text to the server and stored in a variable. Then, nothing stops the Web application from displaying the sent password to the user, in the case where the very same script that has received the password is giving you the feedback about the password change.
On the other hand, if a whole other module gives you the password in plain text (perhaps a password recovery function), then you could conclude that it is not hashed.
Edit: To avoid any confusion, in this case "plain text" does not refer to SSL in any way, it simply suggests that the password is not sent pre-hashed to the server.
Comment: You cannot conclude that the password was stored in plain text, but please note that being **not hashed** does not exactly mean that the password is being stored in **plain**.

It's possible that some (reversible) encryption is used, but from a security standpoint it's almost the same as being stored in plain text.

If someone gains ilegitimate access to the server's database to obtain the "encrypted" version of the password, they're equally likely to be able to obtain the private keys to decypher it.

The only thing you can conclude is that you should **never trust** an administrator.
Comment: This doesn't include the possibility that it was simply stored in the session from page to page, and that they faked it when they said authoritatively "it was changed to password1". They could have simply assumed "Well, if it wasn't changed successfully it wouldn't have made it to this page, so we can safely say whatever was sent was successfully set."
Comment: @corsiKa We could bring up many different cases like what you just described and without seeing the actual code, we can only suppose. The important part is the conclusion.
Answer: You can't conclude the password was stored in plain text if it is redisplayed soon after you changed it.   On the other hand if it is displayed after a while (days for instance) it may be a good hint that the password is indeed not hashed (it is stored in plain text or encrypted).
Anyhow, redisplaying a password is clearly not a best practice because it may compromise much more than the web site that is actually being visited.
Answer: As others have mentioned this doesn't necessarily mean the password is stored in plain text but is a bad sign and bad practice.
Some ways to determine if your password is stored in plain text are:

Using the password recovery to see if it's emailed to you (this indicates plain text or 2 way encryption at the most).
Check the password requirements, if there's a low max length (for example 15 - 20 chars) that's a good indicator that it's stored in plain text.

In general you should be using a unique password for every site, especially if you see any indicators that it's not stored properly.
Comment: If there is low max length it indicates that the developer does things because they sound good or because they are done in other places, without questioning whether it's a good idea. It doesn't indicate it's stored in plain text. Many high profile companies do this, including microsoft, blizzard, my bank, etc
Comment: The most common reason I've seen for a low max length is it's stored in the DB as varchar(15) for example. It's possible it's simply applied for no reason but that's why I said it's an indicator rather than 100% sure.
Answer: No it doesn't. The password is probably sent to the page where it's displayed to you and at the same time it's stored. We cant say if it's stored hashed or not but displaying the password to you does not mean it's not hashed. Like the other answers, I do agree that it's a terrible idea to show the password on the next page in plain text. It's bad anyhow to show it. Not the best example but what if you changed your password when you're (in your case) with a student next to you. You tell him to turn around while you type in your password. You say you typed in your password to him, he turns around, the next page is loading and the person can just see your password. My friend was in the same situation and I saw his password.
Answer: Just ask the admin.
Really, my experience is that they'll tell you if they're storing the password in plain text.
To answer your question directly, no based on the information you've provided it's not possible to know if the password is stored (locally or remotely) in plain text beyond that session.


What is the point of the infrared focus markers?

Question: I am talking about the red values that comes after the infinity value. Why do they exist and how do you use them properly?
Comment: There are no infrared focus markings in the image you have included. It looks like you obtained this image from Digital Photography School, where they use it to illustrate [focusing range and distance scale](https://digital-photography-school.com/what-the-numbers-on-your-lens-mean/), not anything specifically related to infrared photography.
Comment: Possible duplicate of [Why is infrared light's focus point different from that of visible light?](https://photo.stackexchange.com/questions/70407/why-is-infrared-lights-focus-point-different-from-that-of-visible-light)
Comment: You should see page 11 of this Canon lens manual, at https://www.usa.canon.com/internet/portal/us/home/support/details/lenses/ef/telephoto-zoom/ef-70-200mm-f-2-8l-is-ii-usm?tab=manuals    They may be surprised to hear that.
Comment: Please include an image of what you are asking about
Answer: Lenses may have different markings, which include:

Lines associated with different focal lengths in various colors.  Such lenses are varifocal zooms, where the focus point changes with the focal length. This is in contrast to parfocal zooms, which maintains focus when focal length is changed.
Lines associated with aperture F-numbers in various colors. These are depth of field indicators.
Red dots and lines, often unmarked, such as what osullic describes. These are infrared focus indicators. They are used to correct focus when using infrared film. They are often not needed for digital infrared because focus can be adjusted using Live View.
Dots or lines near the aperture ring. Often associated with the letters W or T. These show the aperture range for wide and telephoto focal lengths on variable-aperture zooms.

According to the EF70-200mm f/2.8L IS II USM manual, the red 70 and 100 are infrared indices (emphasis added).

The infrared index corrects the focus setting when using
  monochrome infrared film. Focus on the subject
  manually, then adjust the distance setting by moving the
  focusing ring to the corresponding infrared index mark.

The infrared index position is based on a
  wavelength of 800 nm.
The compensation amount differs depending on
  the focal length. Use the indicated focal length as
  a guide when setting the compensation amount.
Be sure to observe the manufacturer's
  instructions when using infrared film.
Use a red filter when you take the picture.
Comment: The indicators on the 70-200 *ARE* infrared markings... as explained in the Canon 70-200mm owners manual (pg 11).
http://gdlp01.c-wss.com/gds/2/0300003612/02/ef70-200f28lisiiusm-im3-eng.pdf
Answer: Focal length --- The distance from the lens to the image plane when the camera is focused at infinity ( ∞ as far as the eye can see). The flag on the field --- each color of light comes to a focus at a different distance. Violet has the shortest focal length because violet has the shortest wave length. Green comes to a focus next, followed by yellow, then red. Infrared comes to a focus the furthest downstream from the lens because infrared has the longest wavelength.
Because each color comes to a focus at a different distance from the lens, the size (magnification) of image for each color will be different. The longer the wavelength, the greater the projection distance (lens to image), and the larger the image will be.
This phenomenon is called "Chromatic Aberration". Hat's off to John Dollond, an optician, in 1757; he configured a lens array consisting of a strong positive lens made from flint glass and a weak negative lens made from crown glass. This combination mitigates but does not eradicate chromatic aberration.
His lens creation is called an achromatic lens (without color error). In this design, the red image and the blue image come to a focus on the same plane. Lenses that are not well corrected for chromatic aberration display a color fringe that outlines the rim of objects. This fringing is due to the fact that the total image is comprised of an array of different size images. The longer the projection distance --  the larger the image.
Camera lenses are not usually corrected for the extra-long throw of infrared because mostly we image in the visual range.
If we image in the infrared range of frequencies, these images will be out-of-focus unless we manually make a correction. Hence, infrared has its own focusing index marked on the lens barrel.
Comment: My answer is based on the posters verbal description. My answer explains the normally red dot or line adjacent to the infinity index on the focus scale of many lens barrels.
Answer: I am not sure if you are asking the wrong question (in respect of the image you have linked to), or if you are linking to an image that doesn't show what you are asking about...
Look at this image - the engraved distance that aligns with the larger black dot is the distance that is in focus for normal photography. The distance that aligns with the smaller red dot is the distance that is in focus for infrared photography. The lens focuses visible light and infrared light in different ways, so the lens is focused on a different distance depending on if you are photographing using visible light or infrared light.
Comment: The 70mm/100mm markings on the 70-200mm are IR markings; the offset varies with FL. Some zoom lenses show the offset for some FL's as shown, and as seen in this image: https://www.flickr.com/photos/steevithak/7276073576/
Others show it as an arc for all FL's as shown in this image: https://www.flickr.com/photos/steevithak/7987369476/
Most modern lenses do not show the IR offset at all... I think it is because modern lenses have a very short focus throw (i.e. the offset would be very small).
Comment: @StevenKersting Digital cameras usually don't have the option to shoot in infrared, so there isn't any need to correct focus for infrared.
Comment: Good point...most have an IR filter over the sensor.
Comment: the lens does _not_ focus visible light and infrared light in different ways.  The angle of refraction is simply dependent on the frequency of the light and lens designers do not typically go to the effort to align IR with visible frequencies.
Answer: As far as I know, those markers are related to infrared light. Because infrared have longer waves than visible light, lenses need different markers when you take photos for infrared photography.
Answer: The 70-200mm lens shown has two infrared indices, one for 70mm and one for 100mm.  Since IR filters block visible light, the markings are used for manual focus using the range scale rather than the viewfinder.
Comment: The 70-200mm shown does have them; one for 70mm and one for 100mm.


How do you determine power flow direction in a transmission line?

Question: Below is a picture of a typical transmission line(about 200 kV). Is there a simple physics experiment which can be performed safely near the line, to determine the power flow direction. Or in other words: where is the generator and where a consumer.
Comment: given its AC i think you might struggle as there shouldn't be any difference between the forward voltage and the reverse.
Answer: Actually, you don't need to measure things at two different positions along the wire to determine the power flow. You can do this with measurements taken at a single position. You must measure both current and voltage. The measuring device is built so that it rotates based on the relative phase of the current and voltage; and the direction of rotation corresponds to the direction of power flow. That's what happens in the power meter connected to your house. If you couldn't measure power flow this way it would be very hard for the electric utility to charge you for power.
EDIT: The power meter in your house of course touches the wires, but standing on the ground under a transmission line you can do something similar. You can have two pickups, a coil and a straight antenna, and you could feed them into an xy-oscilloscope. Pure reactive power should show a straight diagonal trace, and real power should show a circular loop. The problem is that you won't be able to see the direction the loop is tracing...clockwise or counterclockwise. You would need to compare the direction of rotation to a known field source, e.g. a short line you've set up purposely for calibration. You've got to make sure you're consistent with the relative physical orientation of the two pickups. In effect you're measuring the Poynting vector.
If you had two guitar amplifiers, you could amplify your pickups and feed them into an ordinary household power meter, which is already set up to convert the relative phases into an actual mechanical rotation that you can see. Of course you've still got to orient your pickups consistently and calibrate the direction of rotation against a known power flow.
Comment: Yes, you are right. I was worried about the fact that there is power returning to the plant, but you get that too.
Comment: @Marty: The power meter is not a right answer. The question is to determine power flow direction without a direct connection to the line.
Comment: @Martin--- you can determine all these quantities away from the wire by field measurements. This is equivalent to the Poynting vector business you want.
Comment: @Ron: Not quite. The mentioned power meter measures only the active power. The Poynting vector includes the whole power flow(active + reactive). The active power is transmitted for ex. to your computer. The reactive power can be compared to the foam in a glass of beer : it is not the real stuff, but there is no way to avoid it and the glass must be oversized unless you will have overflow.
Comment: @Martin: The "reactive power" is just the power returning to the plant from the returning line. This is not an objection.
Comment: I believe this is the correct answer. Basically you get a direction when you measure the current. The voltage either leads or lags the current and that defines the power flow. (Uh, not sure which.)
Comment: @Carl: I agree, this is actually a good answer. But the question itself asks for a physics experiment. There is no physics experiments suggested in this answer.
Comment: @RonMaimon There is no power flowing back to the plant.  The plant produces power and that power is delivered through the lines.  Now, *current* does flow back to the plant through the lines.  However, in 3-phase power there is no return line.  The sum of the current in all lines is always zero, so there is no net current flowing through the entire system of wires either!  This is the magic of 3-phase power.
Comment: @Zassou; With 3-phase, you can do the "experiment" on any single one of the three lines. You'll get the power flow for that line. Assuming things are balanced, you will get 1/3 of the total power.
Comment: @CarlBrannen Yes, you are expressing the correct physical picture.  The instantaneous power delivered in any given line will be a sinusoid with the form $A*sin(\omega t-\theta)+B$, and the average, $B$, will be 1/3rd of the total power.
Comment: Wait, power would be of the form $A*sin(2 \omega t - \theta)+B$ if we take $\omega$ to be the frequency of the circuit, or the frequency of the current and voltage.  I don't want to leave my comment with an incorrect equation.
Answer: Measuring T-line power flow from the ground without contact is tricky, especially near the tower. The tower is a solidly grounded structure and tends to sink the EM fields to ground, and the conductors are far from your position (high in the air). Better to move to mid-span where there is no tower and the conductors are closer to the ground. Also better to select a single-circuit power line (the photo above shows a double-circuit tower).
Voltage can be estimated with a capacitive voltage divider by using a horizontal-flat-plate capacitor on a grounded pole. The bottom plate connects to the grounded pole (is grounded), and the top plate floats at a voltage proportional to line voltage. Put a plastic sheet between them for insulation. The measurement will be corrupted by the unequal contribution of the 3 phases, but the closest phase will dominate. Be careful - this top plate can reach several hundred volts depending on the line voltage and distance from line to capacitor. It won't hurt you (too high impedance) but might damage a voltmeter.
Current can be estimated by detecting the magnetic field at ground level using a loop of wire. The varying mag field from the AC current flow in the line will couple to the coil and produce an EMF. If the coil is open circuit, this results in a 60 Hz voltage across the terminals. If it is closed circuit, the result is a 60 Hz current through the loop. Again, the value is corrupted by the 3 phases, but the closest phase will dominate. Us the right hand rule to orient your coil to determine the direction of current flow. Move the coil around to get the largest output.
Calibration is not really possible for an accurate measurement of power flow unless you have a real flow measurement to compare to, but if you are substantially closer to one outside phase than to the center and other outside phase, you should be able to compare voltage phase and current phase to determine power flow direction.
Recall that REAL Current Transformers have an orientation indication, telling you that if power is positive (voltage and current are in phase) then power flow is in a known direction. Your ground set will change power flow direction if you flip the coil around. But you can figure that out by starting with a line where you know the direction of real power flow (away from an operating generator).
If you plan to use an Arduino or other microcontroller to measure and calculate for you, be aware of the voltages and scale appropriately. A high impedance measurement device might see too high a voltage from the plate capacitor and be damaged. You can scale using a capacitive voltage divider before connecting to your measurement input. Start with a high voltage voltmeter connected to top and bottom plate set on highest AC range to get a feel for the output voltage. The indictive coil voltage is a crap-shoot - try putting a 100 ohm resistor across the open terminals and measure with a voltmeter.
Make sense?
Answer: The relevant equation is that of complex power in an AC circuit:
$$\vec{S}=\frac{\vec{V} \vec{I}^{*}}{2}=\frac{V I}{2} \angle -\phi$$
This is to say, the complex power flowing through a line is equal to the complex voltage times the conjugate of the complex current divided by two.  Those not familiar with AC circuits will have a tough time with the complex variables, but let's turn to the following definitions for illustration.  Note that I'm going to establish voltage as the reference angle.
$$S=P+jQ$$
$$\vec{I}=I \angle \phi$$
$$\vec{V}=V \angle 0^{\circ}$$
The real power is $P$ and the imaginary power is $Q$.  The interesting thing to note is that $P$ can be either negative or positive.  Before applying any of this however, you must have a reference direction.  You're looking at the line, you can look either right or left, you establish one of those directions as positive, and then $P$ will follow as either negative or positive and if positive, it flows in the direction you're looking.
Here is an illustration, although I think this differs in convention by the sign of $\phi$.

Now, here is what you need to establish the direction of power flow:

A reference direction
The angle between the voltage and current

Exactly how you measure this is certainly the difficult part.  I will defer to other answer regarding that.  But provided that you do, if $\phi \in (-\pi/2,\pi/2)$ then the power flows in the positive direction and if $\phi \in (\pi/2, 3\pi/2)$ it flows in the negative direction.
Answer: When power is consumed, the voltage and current rises and fall together (with some variation due to power factor).  As you consume energy from the grid the voltage generally stays the same but the current rises and falls depending on your consumption.  As you reduce your demand to zero, the current falls to zero, then when you start feeding into the grid, the current becomes negative with respect to voltage (ie. 180 degrees out of phase).  So to determine energy flow, you need to know the current in the wire and whether that current is negative or positive with respect to the voltage.
You can do this by measuring the voltage and current at the same time (instantaneous values), then multiply them together, if the answer is negative, you are feeding into the grid, if it's positive, you are using power.  How you do this is the tricky bit, a current clamp and a voltage transformer with the output calculated within a micro-controller (ie. Arduino). Could also use a current clamp and an antenna wire near the power wire with a circuit tuned to your mains frequency (measuring the emf), again results calculated via a micro-controller.  Been trying to find a better/easier way to do this without contact, but as yet haven't found an easy answer?   The measuring current via a current clamp is easy, but the voltage transformer and emf antenna for me have produced some erratic results.
Answer: With a high-powered rifle, shoot one of the lines in two at the middle. Observe the two ends. The one that sparks the most is the line going back to the generator.
When these power lines carry DC, I believe it is impossible to easily determine the direction of current flow.
For AC lines, it's fairly easy; one times the 60Hz signal. Use two receivers separated by long enough to get 60Hz out of phase. If the speed of light is 186,000 miles per second, and the speed of wave transmission in the lines is on that order, then a 1% phase difference will need a distance of 0.05 x 186,000 miles/second x (1/60th seconds) = 31 miles.

I learned something from the comments on this question: power companies nowadays adjust the phases of their power lines by putting capacitors and inductors in the line. They do this fairly often and their effect is to modify the relative phase. So if you do measure the field at two points near the wire, make sure that there's not a power station in between your measurements. To learn more about this, try googling "power transmission"+shunt+series
Comment: You're being funny, right? :) You're using the high powered rifle in safe mode by ensuring it's not pointing towards the person using it, but towards the pylon. It snaps the cable in two in the middle, bringing the high voltage cable to the ground, causing criminal damage, a power cut in some local area, as well as your picture in the local newspaper and on police files lol ;)


What is the relationship between angle of attack and wake turbulence?

Question: It is said that when the preceding airplane is heavy, clean, and slow, wake turbulence is much hazardous due to greater angle of attack is requried. However, why does increasing angle of attack result in increase in wake turbulence? (or wing tip vortices)
Answer: It is not the angle of attack - downwash intensity grows with lift squared and inversely to the squares of wingspan and speed. Please read this answer on how wake turbulence forms. Now let's look at the parameters you listed:

Heavy: Yes, the heavier the aircraft, the more lift needs to be created. Induced drag grows with the square of lift.
Clean: Not really. With or without flaps the amount of lift is the same. Only the lift distribution over span might be different, but this does not make much of a difference for the wake.
Slow: Absolutely! Induced drag is proportional to the inverse of speed squared.

What is missing from the list is wing span which lets induced drag grow with the inverse of its square. The angle of attack is only indirectly responsible for induced drag because lift is (within limits) proportional to the angle of attack.
Answer: Wake turbulence is proportional to lift, and lift increases as you increase the angle of attack. Assuming an identical weight and configuration, an airplane on approach will produce less wake turbulence than one in the flare for landing, and an airplane on its takeoff roll will produce less turbulence than one which has rotated.


why do overweight individuals sweat more than ordinary people?

Question: A common phenomenon that I have noticed while traveling in buses is that overweight individuals seem to sweat a lot more than people with ordinary weight. Is this a coincidence or is there some science behind this?
Comment: This study found that only [2.3% of the variation in whole body sweat loss was explained by body fat.](http://www.ncbi.nlm.nih.gov/pubmed/26316511) However, body size had greater effect. Could you update your question to include a link to reputable evidence that overweight individuals do sweat more?
Comment: @Michael_A The study is about exercise and is not ceteris paribus with the study of obesity on sweat.
Comment: The question is based on an anecdotal observation of obese people sweating a lot on buses.  So no the study is not an equal comparison, the study is superior; they specifically isolate the effects of body fat on sweating. It is specific to exercise but what would be equal evidence, does the study need to involve buses?
Answer: Well there are some overall, simplified answers, but every individual is ..well.. individual.
First there is the ratio of volume to area. As interaction between two mediums normally is depended on their common/shared surface. If we state, that an overweight person A has more volume than a skinny person B of same height, A also has a larger surface as B, but not in the same scale the volume is increased.
The easiest way to describe is with spheres, let's assume bellies are kind of spherical ;-) . A sphere with diameter 2r=1d (hint: one dimension) has a surface of π4r²=πd² (hint: 2dimensions; 2nd power 2²=4; d²=(2r)²=4r²) and a volume of $$\pi\frac{4}{3}r^3=\pi\frac{8}{6}r^3=\pi\frac{1}{6}d^3$$ (hint: 3dimensions; 3rd power 2³=8).
So, if we manipulate r it's manipulated to the 2nd power for surface and to the 3rd power for volume.
So, if we double the radius, we have 4 times the surface, but 8 times the volume.
Humans are biochemical machines, we take an energyform we can exploit to fuel our processes keeping us alive. These processes also produce heat, which is kind of a nice sideeffect allowing us to operate in cold climate. But in hot climate we need to get rid of the heat.
As I stated before, interaction is surface based. Person A has a lot more heat producing volume than B, but the surface isn't that much bigger, so A's surface has a higher urgency to interact with the medium around than B's surface (so more sweat for example). Also more tissue produces more heat. But again disclaimer: different tissues have different activities.
Furthermore fatty tissue has an insulating effect, which reduce interaction even more. Other way round the heatloss of an overweight person isn't as dramatic as for a skinny person in sudden cold.
But these are simplified answers, there's much more to it. Like bloodpressure, thyroid, biological activity. Which can be influenced by so many more things.
Comment: Great answer! It would be great to get more about primary and secondary factors of sweating.
Comment: It would be great to get sources here.


How accurate is cisco's "show proc cpu history" compare to snmp's cpu loading?

Question: I'm using snmp to monitor my cisco router's cpu loading, but the number has a large difference with show proc cpu history's output. When sh tells me cpu loading is 7x%, the snmp only gets 2x%. Which number's accuracy is higher than another one?
Answer: The differences will be due to different ways of averaging and also the different sample period.
Some background (I wrote the command):
The intention was that this command was to be used to look for patterns in CPU utilisation, aiding the correlation of transient issues with CPU spikes (specifically call control errors with CPU spikes and call rate on the as5800 series).
"show proc cpu history" is graphing the 5 second CPU value as obtained from the "core" of IOS.
For the last 60 seconds this is accurate, bearing in mind that the values only update every 5 seconds. It will be quite spiky and unpredictable due to the run to completion nature of IOS.
After every 60 seconds an average is calculated from the collected data and stored as a data point in the 60 minute graph.
After 60 minutes an average of the hour graph is calculated and stored in the 72hr graph.
The way that the averages are calculated mean that there are bound to be variances. However it uses very little memory or CPU overhead to maintain the data. Given that the command has to run on the smallest router and line card upwards that was more important than accuracy.
Answer: 'show proc cpu history' can show one minute, one hour or 72 hours of history
(http://www.cisco.com/en/US/products/sw/iosswrel/ps1828/products_tech_note09186a00800a65d0.shtml#showprochistory)
The OIDs for Cisco show 5 second, 1 minute or 5 minute busy percentage intervals
(http://www.cisco.com/en/US/tech/tk648/tk362/technologies_tech_note09186a0080094a94.shtml#topic1).
The difference could be the interval duration being used.
Answer: To a large extent, it doesn't really matter all that much.  One gives you one number, and one gives you a another number nearby.  Use the SNMP one to graph and collect with, and don't worry too much about the 'actual real guaranteed usage'.  This is most likely due to different sampling intervals, and the impossibility of actually getting a instantaneous rate (i.e, in any particular time slice, the CPU is either 100% or 0%).


How to find out the amount of sectors available in a RAID physical disk for replacement?

Question: So, to start with, let me confess I have no knowledge of RAID besides what I read in a few APC mags 5 years back and what the acronym stands for. Everything I know now comes from assumptions and the past day's research. We have a LSI MegaRaid array in our companies DCSERVER. It predates me at the company and I had no hand in it's setup. It consists of 2 drive groups - 2 280 Gb SAS drives make up a 280 Gb virtual drive, and another set of 4 1Tb drives makes up what was (I believe) an almost 4 Tb virtual drive. Based on this (and no other information, because I couldn't find where to look for it) I think we use only striping, no mirroring on the second group, whereas the first is just a mirrored drive for redundancy.
So that's the situation. A little while ago one of the drives in the second group died. Right now it shows as a 0 Bytes Unconfigured bad drive. The virtual drive it is in shows as degraded but still works for now. The physical drive itself (and the other three in the same group) are all the same drive (Seagate ST31000640SS fwiw) but this drive is now EOL and we can't get one from our supplier. I have read that I need to know how many sectors are in the disc when formatted, so I can replace it with one that has more, or at least no less. Most of the info I have thusfar I got from MegaRAID's Storage Manager, but sectors in a disk doesn't appear to be listed anywhere. Does anyone know the best place to go looking for this?
I know fsutil will give that to me for the virtual drive, will this correlate exactly or functionally to the number in one physical drive? I would also be incredibly grateful for any answer that does not require me turning off/restarting the server or removing the disk.
Comment: Why don't you get a warranty replacement drive?
Answer: The Seagate is a standard 1TB nearline 3G SAS disk. It's end-of-life because it's been replaced by 6G SAS variants. You can find the specific model easily on eBay if you need. But a good replacement is the Seagate ST1000NM0001.


Active Directory in a DMZ

Question: What is the best way to manage user accounts for Windows servers in a DMZ? We are expanding our web presence and adding several IIS servers to our DMZ. I would prefer not to manage a bunch of local accounts or, on the other hand, expose our internal Active Directory servers directly to the DMZ either. Is there a standard approach to this problem?
Answer: You can create a separate AD for the DMZ and really lock down the domain controllers in the DMZ.  That way you have two spots to maintain accounts, and you can take it a step further by establishing a trust so that you can log into your DMZ AD with your internal AD accounts.
Answer: The Active Directory team at Microsoft has released a guide with best practices for running AD in a DMZ.
Active Directory Domain Services in the Perimeter Network (Windows Server 2008)
The guide covers the following AD models for the perimeter network:

No Active Directory (local accounts)
Isolated forest model
Extended corporate forest model
Forest trust model

This guide contains direction for determining whether Active Directory Domain Services (AD DS) is appropriate for your perimeter network (also known as the DMZs or extranets), the various models for deploying AD DS in perimeter networks, and planning and deployment information for Read Only Domain Controllers (RODCs) in the perimeter network.
Because RODCs provide new capabilities for perimeter networks, most of the content in this guide describes how to plan for and deploy this new Windows Server 2008 feature. However, the other Active Directory models introduced in this guide are also viable solutions for your perimeter network.
Answer: It would depend on how you intend to manage the users.
If the users already exist internally, my approach would be to use the existing AD structure.
If it's just a matter of having 10 IIS boxes, that all need the same user account access, then stand up a seperate AD structure inside the DMZ.
If the user accounts only need to exist on each box.  Then local accounts will be the best approach.
As with everything, exposure is a trade-off for security.  But a properly configured firewall will not put your AD at significant risk, just by joinging your IIS boxes to the domain.

Active Directory in a DMZ


Two free basis of a free abelian group

Question: We have a free abelian group $A(X)$, where $X$ is its free basis, and let $Y$ another free basis for $A(X)$. We know that every $g\in A(X)$ can be expressed as $g=a_1x_1+...+a_nx_n$ where the $a_i$'s are integers and $x_i$'s are pairwise distincts elements of $X$ (this is called the normal form of $g$ with respect to the basis $X$), and similarly for $Y$.
Let $x\in X$.
I want to prove that there exists $y\in Y$ such that $y=a_0x+a_1x_1+...+a_nx_n$ with $a_0\neq 0$, that is, $x$ appears in the normal form of $y$ with respect to the basis $X$.
I tried to use that $Y$ is a free basis, but I don't know how to find such a $y$.
Any hint? Thanks :)
Answer: Take any y in Y and $a_0=1$. That will work by the definition of a basis.

Two free basis of a free abelian group


Sharepoint 2013 Navigation

Question: It is possible to change the name of my Sub site Navigation? At the moment I have two links, One is called Issue Log which takes me to my homepage and the another also called Issue Log which takes me to a custom list.  I would like to rename the Homepage Link to be Issue Management
Comment: Click the gear icon which is present in your SharePoint site > Then click on site settings > Once you are in site settings page, click on the navigation present under Look and feel. Once you are in the navigation page, under "Structural Navigation: Editing and Sorting" go to current navigation and select the link which you would like rename and click on edit then change it.
Answer: You can alter the navigation items from the site settings page:

{yoursite}/_layouts/15/settings.aspx

You can access this section from the Settings cog too:

On the site settings page you should have a Look and Feel section. Check for a Navigation option in this section:

If you don't see this option, you may first need to enable the site publishing feature. To do so, click on site features:

Scroll down and locate the publishing feature, and then enable it:

Go back to site settings and click on Navigation. On the navigation page you will see the section that corresponds to your left hand side navigation on the site:

Use the controls to add, remove and edit links. You may need to create a new link called "Issue Management" and have it point to your list.

Sharepoint 2013 Navigation


Can I create a boot disk for 10.6 or 10.7 on a PC (to be used on a Mac?)

Question: I have a Macbook Pro that had a hard drive failure, I've replaced the hard drive but I don't have a boot disk of any kind.  I could just order a Snow Leopard DVD, but I have to wait a few days for this.  So I'm wondering if it would be possible to download either Snow Leopard or Lion to a DVD from a PC that I have access to, that I could then use as a boot disk on the Mac.  Is this possible?
Answer: Is it humanly possible, if you received an ISO from some source, that you could create a burnable disc from a PC? Yes, no reason why not.
That being said, if you have upgraded the firmware on a recent-enough MacBook Pro, and have a fast enough connection to pull down a OS install disc, you could use internet recovery:
Apple's Knowledge Base Article for Internet Recovery-Capable Macs
I believe this won't work if you hadn't run this updater on your Mac after already upgrading to Lion, but it would pull down a recovery partition of less than a GB first, from which you could at least browse the web with the 'get help online' Safari Kiosk mode, or go on to do a full reinstall.
Beyond the 10.6 disc, there is also a USB drive for Lion that can be purchased as well, of course. Good luck
Comment: Actually if I recall correctly there should be also an option to restore from Time Machine. Might be quicker.
Comment: @bdecaf Would you be able to provide more info on this? Sounds interesting.
Answer: The Mac OS is copyrighted and Apple does not give it away.  It comes with a Mac when you buy the Mac, but otherwise you have to buy it.  Thus there is no legal way for you to get a copy without paying for it.  Apple only supports downloadable software purchases via the AppStore, which only runs on Macs so far.  So no, there's no legal way for you to download the OS on a PC.  That said, you can probably find an illegal copy of an install DVD somewhere.
Don't you have the DVD that came with your MacBook Pro? That's the normal way to recover.  I guess you're not near an AppleStore, either, or you could go there and have them install Lion on your MBP.
Do you have a TimeMachine backup?  Some other kind of backup?  If you had a Carbon Copy Cloner backup then you could boot from that.
Answer: Yes, technically you can create a Mac OSX boot disk on a PC. For Lion, you will need the image, a file named InstallESD.dmg (which can be written using something like UltraISO).
You can acquire the needed file either by downloading the Lion installer from the Mac App Store (requires a Mac initially, you can copy the files to a PC afterwards) or downloading the file from other sources (hint:torrents).
Legally you should be covered in most jurisdiction since installing Lion requires your purchased it (and usually you are entitled to own a backup copy) but you know you shouldn't get legal advice from the Internet.
Answer: If you own your legal copies of software, then you can use Alcohol in Windows, or Daemon tools, or even Nero (Nero is tricky) to do a 1:1 burn from your DVD into the HD, or from a HD into a DVD.
You can also buy MacDrive for Windows to look into HFS+ disks, specially double optical disks with different files viewable depending if you insert the CD or DVD into a Windows or a Mac computer.
I once had a mac with a broken optical drive (this works in MacBook air too), you can copy your free linux or any other boot disk into a blank external HD, or even a flash drive (they are extremely fast) and boot your mac with holding the Option (Alt) key, boot img will show up in the white screen.
This link has pretty much all the info you need for copying CDs in windows.
http://www.tomshardware.com/forum/243423-32-image-flash
I believe I can trust that you will assume responsibility over your actions, and that you own all the licenses to the software you want to copy.
I am just giving information here. What you do with it is your problem, not mine.


Why are all the textures in my file pink?

Question: I made a character, and its one of my first times texturing, and I saved my character into a new folder, and when I came back to the model ALL the textures were pink, I used to know what to do, but I stopped texturing, how do I bring my textures back?
Answer: Pink means that the texture files are missing.
If the texture files are still on your system, then it sounds like the textures are referenced relative to the blend file (the default behavior). This means that if you move the blend file and you don't move the textures, blender won't be able to find them.
There are several things you can do:

Use the Find Missing Files operator in Info > File > External Data to let blender try to find the files for you:

This will give you a file browser with which you can select a directory which you think contains some (or all) missing files. Blender will then recursively search through all files and subdirectories of the selected directory for files with the same names as the missing files.
Note that if the directory is big (contains lots of files and subdirectories), this might take a while. Blender will appear frozen while the operator runs, but don't panic.
With the blend file in the original location (so the textures are loaded correctly), press Make All Paths Absolute in Info > File > External Data,
then save the blendfile. Now blender can find the textures (provided they don't move) no matter where the file is on the system.
Pack the textures into the blendfile. Press Info > File > External Data > Pack into blendfile. This will embed the image data into the blendfile itself, so your file may become rather large. However, this means that blender will always be able to find the textures no matter what (even if the file is put on another computer).
Move the textures to be in the same position relative to the new blend as they were to the old blend. E.g., if the textures are in a directory that is in the same directory as the old .blend, move that directory into the directory containing the new .blend.
Comment: Note, in my case, "missing" simply meant that Blender didn't like the file name. `MyTexture_1024.jpg` did not work, but renaming it to `MyTexture.jpg` did work.
Answer: Pink display means missing texture image. Maybe you forgot to pack the image files or save them to external files, before saving the .blend file and closing Blender.
If that's the case, unfortunately you'll have to re-make the texture images..
Answer: Altought this is resolved already, here is a help:
When you open texture tab, find this:

Make sure to change pink color to black. Than it should be fixed, I think...
Comment: Welcome to the site :) This is useful information to have here, thanks for adding it. But note that this won't bring the textures back, it will just change the pinkness to blackness instead.
Comment: Ohhh that's where the Pink of Doom™ comes from!
Comment: @gandalf3 By the way, there is no need to Pack into .blend file always you save game- it is annoying and hard to remember. You can check the box in _File->External Data_ so it does it automaticly;)
Comment: @Meri On the top you could look for 3 icons - Earth, cube and checkers. Click on cube.
P.S. This is old post, those days I had so low knowledge of Blender. It has grown a lot so this answer made by me seams to be foolish:D
Comment: @AdriansNetlis. Hi. Please can you tell me where I can find the texture tab? Because in Textures I have brush-texture and brush mask. I can't find the screen what you are talking about.
Comment: @AdriansNetlis Thank you but I can' find those options. I am in the cube and I have opened every ticker. I'll do the model again. Thank you for answering.
Answer: I had a similar issue where the textures disappeared. You should make sure the textures are downloaded. If you save your files in iCloud I suggest you double check the folder with the model and texture.


Which keys are used to activate substitution in Ultimate Ninja Storm 2?

Question: Which keys are use to activate substitution in Ultimate Ninja Storm 2 on PC?
Comment: PC? Ultimate Ninja Storm 2 is only available for the Xbox 360 and Playstation 3.
Comment: What console are you playing this on?
Answer: While playing as that character in free battle, press start and go to 'Combo List'.
Answer: Ignoring the fact that the game isn't available on the PC, here's the answer:
Substitution Jutsu is activated by pressing the same button you would use for guarding/blocking just before an attack would hit you. If the attack was a melee attack, you would be placed behind your opponent, ready to retaliate, and if the attack was a ranged attack you would simply appear above your current position, avoiding the attack.
On the PS3, the default buttons for blocking are R2 and L2 (the lower shoulder buttons) and on the Xbox 360 the default buttons are the corresponding LT and RT.


Which Catalog I will buy Pantone Solid or Color Bridge?

Question: What is the difference PANTONE 340 U and PANTONE 340 UP? Is the UP color CMYK process printed color or not? Because they are really different. I want to buy pantone catalog today and I don't know Color Bridge is enough for me? For example I am generally using Pantone 320 C and this color is our company branding color. If I send something to print I am using Pantone 320C, If I sent something to print as CMYK, I am using 100,0,31,5 CMYK. So Color Bridge is enough for me? What is including this cartela?
Answer: I would recommend getting a Color Bridge set that includes both C and U. Each Color Bridge will contain a solid swatch next to its process analog, so you get everything in two guides.
Comment: *That is, everything but some specialty libraries that don't generally have process analogs, like metallics, hexachromes, etc.
Comment: I bought Color Bridge today. So this first square is showing how special pantone solid color will seem on paper and right side square is showing CMYK process color? If it's right I bought right and perfect one. But difference is very big between special solid color and CMYK process color.
Comment: Yes. It's easier to see with a loupe, but the left is generally the solid ink, while the right is PANTONE's official CMYK formula. Some colors are much closer than others. The colors that are farther off are due to pigments mixed into the ink that fall outside of the CMYK gamut, like fluorescent colors. It should be noted that many modern printers, like the HP Indigo series and some 6-ink printers, can come closer to the solid swatch than the guide may indicate.
Answer: Here are the most recent Pantone Colour Suffix Differences from the PANTONE Help Center:

CV = computer video. This designation is used to denote that a color is an electronic simulation of a PANTONE Color. It is used in older versions of software applications that license PANTONE Colors, e.g., Adobe Illustrator, Macromedia FreeHand, QuarkXPress, Adobe Photoshop, etc.
    CVC = computer video, coated paper. This denotes electronic simulation of the color specifically as it appears on coated paper; "CVU" does the same on uncoated paper.
    C = coated paper, i.e., PANTONE 185 C
    U = uncoated paper, i.e., PANTONE 185 U
    CP = coated paper, process simulation, i.e., PANTONE 185 CP (used in PANTONE+ COLOR BRIDGE COATED).
    UP = uncoated paper, process simulation, i.e., PANTONE 185 UP (used in PANTONE+ COLOR BRIDGE UNCOATED).
    The following designations for PANTONE Colors used in earlier versions of PANTONE COLOR BRIDGE are now obsolete:
    PC = process simulation, coated paper, i.e., PANTONE 185 PC.
    UP= uncoated paper, process simulation, i.e., PANTONE 185 UP.
    EC - Euro process simulation, coated paper, i.e., PANTONE 185 EC. This was used in the European version which is now obsolete.


ESP8266 & websockets

Question: At the moment, I'm using various operating systems and devices like the Raspberry pi to control lights and other stuff over websockets. I use websockets since they added the support on Chrome. I write a lot of Javascript stuff for fun. Websockets allow you to communicate with another server without the need of reloading a page. It's a lot better than Ajax. Once the connection is open with a web server data can travel both ways. No unnecessary headers to send. No unnecessary requests. You just send only the data you want, this in both directions. AND FAST, DAMN FAST.
For example I use Javascript's requestAnimationframe to send RGB values (based on music frequency) to lamps connected to the network. requestAnimationframe executes approximately at 60 Hz. But that's not the highest speed, I also created some "web controllers" to control servos and other stuff with touch and mouse events. In that case it probably touches transmission frequencies of 200-300 data packets (normally I use JSON- encoded strings) or more per second.
Websocket servers have also broadcast which allows you for example to control multiple RGB lamps based on the music you play from basically every modern device that has a browser. I don't use "normal" sockets because of the simple fact that there is no support for sockets in a standard web browser. So I would need to create a custom iOS app, custom Windows app, custom Android app. I said that we know that websockets are made for a fast multi-user / multi-device / bidirectional communication. And it should be really fast or it's useless.
Lately I have a lot of fun with electronics and MCUs, so I made even more lamps and stuff controlled from Arduinos, ATtinys and other microcontrollers. I'm new to C++ but since I write Javascript code since the previous century I just have to slightly modify old Javascript functions to run in the Arduino IDE.
But for sure I'm not ready to write a perfect library for an MCU, so I need to use what I find online.
Apparently there are not many people into websockets. I tested 2-3 Arduino websockets libraries and couldn't get them to work properly.
The last one I tested(Links2004) works but I can't send a 4 decimal string faster than 2 times per second or it crashes.
All I did was to add this code for testing:
void onWebsocketMessage(uint8_t * payload) {
 analogWrite(13,atoi((const char *)payload));
}

Where payload is the data received.
Problems that could slow down/crash everything:

My code. Does atoi take too much to execute?
My code. Is the (const char *) cast filling memory?
The lib itself?

I know that the CPU memory or whatever else is not the problem because of this video:
https://www.youtube.com/watch?v=8ISbmQTbjDI
He gets realtime stats from the controller at 200-600 Hz.
While it's supercool and I could just install that "custom firmware" I prefer to stay in the Arduino IDE for now.
How to fix websockets on the ESP8266 device using Arduino IDE?
Or maybe can I extract only the websocket part from that firmware (CNLohr's Video)?
Suggest another lib?
I posted here because I use the Arduino IDE. And the ESP8266 has also been part of the Arduino world for a while. And maybe some not so popular Arduino-based websockets work also on the ESP8266.
Wouldn't it be nice to control your ws2812b strip with a web interface showing the preview like this?
http://jsfiddle.net/dgws3usa/5/

EDIT
links2004 @ github

The network should be fine. It's a relatively expensive Cisco/Linksys N router at 20cm/8inch away from the ESP8266 module.
Luckily the module I'm using is one of the modules listed in the Arduino IDE, the MOD-WIFI-ESP8266-DEV, but I have another one with fewer GPIOs.
I just noticed now that I programmed it at 80 Mhz instead of 160 Mhz.
The program I uploaded consists only of the basic websockets server example with in addition just the code posted above.
If atoi is the problem/is slow, what are other ways to convert the received array to a string?
I use both the latest versions of the Arduino ESP8266 port and the arduinoWebSockets. At least I guess so. I followed the install instructions one day before I asked this question.
By crash I mean, while moving the range slider, if updating in realtime with addEventListener('input',function,false) at some point (after 1 sec/ 3-4 messages send/received) it stops sending or receiving data. By the way, the video you posted seems to work properly with a lot more code. Also that guy updates in realtime with oninput vs 'onchange', which would only update when the user releases the slider.
I think for now I can't use Serial.setDebugOutput(true); as I didn't get the serial communication working. I'm using a cheap CH340G to program the chip.

Japanese post.

I'm doing exatly the same thing but in a much simpler way. No web server, no ping pongs, no serial stuff, I don't use complex functions to elaborate the web server's data. Altough his example works.
He is doing, code-wise, a lot more than I do.
for(i=0; i<4; i++) {
  mask[i] = client.read();
}
byte m_data[data_len];
char data_c[data_len];
Serial.print("Receive Data = ");
for(i = 0; i1-0x30);
    break;
  case 3:
    data_b = ((data_c[0]-0x30)*100) + ((data_c1-0x30)*10) + (data_c2-0x30);
    break;
  }
  LED_PWM(data_b);

My full "test" code:
#include <Arduino.h>
#include <ESP8266WiFi.h>
#include <ESP8266WiFiMulti.h>
#include <WebSocketsServer.h>
#include <Hash.h>
ESP8266WiFiMulti WiFiMulti;
WebSocketsServer webSocket=WebSocketsServer(81);
void webSocketEvent(uint8_t num,WStype_t type,uint8_t * payload,size_t lenght) {
  switch(type) {
    case WStype_DISCONNECTED:
      break;
    case WStype_CONNECTED:
      {
      IPAddress ip=webSocket.remoteIP(num);
      }
      break;
    case WStype_TEXT:
      analogWrite(13,atoi((const char *)payload)); // MY CODE
      webSocket.broadcastTXT(payload,lenght);
      break;
    case WStype_BIN:
      hexdump(payload,lenght);
      webSocket.sendBIN(num,payload,lenght);
      break;
  }
}
void setup() {
  pinMode(13,OUTPUT); // MY CODE
  for(uint8_t t=4;t>0;t--) {
    delay(1000);
  }
  WiFiMulti.addAP("ssid","pass");
  while(WiFiMulti.run()!=WL_CONNECTED) {
    delay(100);
  }
  webSocket.begin();
  webSocket.onEvent(webSocketEvent);
}
void loop() {
  webSocket.loop();
}

I normally write Javascript code. Converting a string to a number or vice-versa is much simpler. num=1; str=1+''; num=str*1; So all this binary array is relatively new for me.
Note that while I convert the binary array to an int now. In the future I need to convert that to a string which then will be parsed. Something like JSON. And so update more channels per message.
On the client side, like I said, I'm sending the data really fast. So if there is no buffer on the server side that could be a problem. Solving that is simple: requestanimationframe. Continuously check if the input changed. That allows you to send the data every 16-17ms. So 60 Hz. Not slower, Not faster. But again that should be the maximum pause between messages.

I said that I will reprogram it at 160 Mhz now and hope there are other ways to convert the received data faster and hope for updates relative to my code.

EDIT2
Right. The serial works. Reprogrammed the ESP8266 At 160 Mhz.
The error I get when when I set Serial.setDebugOutput(true); is:
LmacRxBlk:1

If you need some other information just ask.
EDIT3
Sorry for the late response.
webSocket.broadcastTXT(payload,lenght);

Broadcasting seems to be the problem. I just have a few minutes so for now I can't do the describe debug stuff... But I will do as soon as I have a little more time.
EDIT4 for Aditya Tannu
Added
#include <NeoPixelBus.h>
#define pixelCount 16
NeoPixelBus strip = NeoPixelBus(pixelCount,13);

Inside the webSocketEvent function
case WStype_TEXT:
for(uint8_t i=0;i<pixelCount;i++){
 strip.SetPixelColor(
  i,
  RgbColor(i==(atoi((const char *)payload)%pixelCount)?255:0,0,0)
  // i need to put the above outside of the loop.
  // it does not work if i do so
 );
}
strip.Show();
break;

HTML JS
var ws,form;
function msg(a){
  console.log(a);
}
window.onload=function() {
  form=document.getElementById('form');// change
  ws=new WebSocket('ws://IPNUMBER:PORT');// change
  ws.onopen=function() {
    ws.send('0');
  };
  ws.onmessage=msg;
  form.addEventListener('input',function() {
    ws.send(this.firstChild.value) // firstchild is the range
  }, false);
}

vid, I use a logic level converter from 3.3v to 5v: pca9306.
EDIT 5 for Links2004

I think I should rework the examples. It looks like most users don't
  understand it well.

Nono. At some point you need to broadcast back the actual position anyway.
Sorry. I forgot to test the debug stuff again. But we know it's the broadcast. We just need to send back data only when there is not too much traffic.
Answer: I tried to port Charles Lohr's implementation to esp8266/Arduino. An initial working version is up here: https://github.com/AdySan/ESPSocket
I'm able to get ~150Hz without any disconnections or crashes. I'll keep working on it to add more functionality and hopefully improve speed.

ESP8266 & websockets


How can I create custom drum beats in GarageBand?

Question: GarageBand's main solution for adding drums and rhythm to songs appears to be through pre-made drum loops and the new session drummers.  I desire more customizability with the beats I add to my songs.  How can I create custom beats in Garageband?
Comment: There is a software recommendations site, actually. http://softwarerecs.stackexchange.com/
Comment: By the way, if anyone would like to create a Garageband tag that would be superb.
Comment: I think you've asked the wrong question for this site. I suggest you edit this and instead replace pretty much the whole question with "How do I create custom drum beats in Garageband?" It is possible on the OSX version, although not on the iOS version if I recall correctly.
Comment: Okay I made some edits.  Would you suggest that drum machine software recommendations/usage belong on Super User or a similar site?
Comment: I'm not sure if any SE sites consider product recommendation requests on-topic. You might look for some more traditional forum sites for that.
Comment: The edited question seems to fix the original problem.
Comment: There is an add on extra that gives you a set of virtual drummers, you can tweak what drums they play and how they play them.
Comment: I'm asking on [Software Recs](http://softwarerecs.stackexchange.com/questions/22924/free-inexpensive-beat-grid-drum-machine-plugins-for-garageband).
Answer: GarageBand employs loops as one way of creating drums, but you're right, it is very limited especially if your interested in keeping up to date with pop music (trap, EDM, etc). There are a couple of solutions:
Drummer Tracks
This was originally a feature with Logic Pro X and has since migrated to GarageBand (OS X only). As Dave mentioned in the comments below your question, you can select a drummer from a set of styles (R&B, songwriting, etc) and select from several drummers within each style. Each drummer can be further customized by decided how many fills they perform, what sub-set of drums they use and even more. I feel it is a large step above using loops, but can be limiting if you don't use it properly. If you have all of your drummer regions set exactly the same it can be very boring so make sure that for each region it is tweaked to account for the varying dynamics that are part of most songs.
Software Instrument
This by far is the most flexible way to create drums. Create a new software instrument track, select a drum kit and get to it! The one issue with this method is that you need to know how to create a drum beat. I teach a music production course at the high school that I work at here in Toronto and lesson one with drums is that for most styles of music, the most basic drum beat possible is playing the bass drum on beat 1 followed by the snare drum on beats 2 and 4. This is a good starting point.
Another technique that I employ with my students is getting them to copy existing drum beats (bass and snare only) so that they get a feel for how producers put beats together. Of course, there are other aspects to drum like using the hi-hat, toms and cymbals.
Of course, any time you create rules in music there are a ton of examples that break those rules. I think the ultimate rule is that if it sounds good, then go for it (very subjective, I know). Hopefully this gets you started.
EDIT - Extra Info
Beat Grids (Note: Not available in GarageBand)
There are some DAWs (Digital Audio Workstations, which is what GarageBand is) that feature a tool that I call a "beat grid". There may be a more correct term for this. Here's what it looks like in a DAW called FL Studio:

It allows you to toggle on/off each sound of a drum kit. Each row represents a sound in a drum kit and each column represents a point in time in which that sound is triggered. This allows the producer to hear what their beat sounds like in real-time without having to worry if they are playing properly because there is no playing involved, only clicking of the mouse on the grid. If you have the funds, Logic Pro X is almost a carbon copy of GarageBand, but under the hood it's much more powerful. It has an instrument called Ultrabeat that allows you to use a beat grid.
Comment: Yup, what you just described is literally what that "beat grid" thing is. It's very easy to use. My students who do not understand music that well love using it! You do not have to have a good handle on what a 16th note is...you just need to use your ears and tweak your beat. Unfortunately, GarageBand does NOT have this feature (at least to my knowledge). I highly suggest Logic Pro X.
Comment: A drum machine is pretty much an instrument whereas a beat grid is a method of inputting note information in a very intuitive manner. Check out something like BPM by MOTU (it's a drum machine). It also contains a beat grid for creating beats. It's just one of many and one that I've used. [MOTU website](http://www.motu.com/products/software/BPM)
Comment: I'm thinking this is probably the best answer anyone will get on this site.  I'll probably poke around for some plugins on Software Recs.
Comment: You should definitely look into making them yourself. The problem with using tools that generate beats is that they are never as customizable as you need them to be. I'll update my answer, there is one last type of drum creation tool that is highly effective (beat grids)
Comment: Ideally I'm looking for a drum machine with high quality samples—something that provides better quality than drum kit instruments and more intuitive looping, but still lets me place every single hit.  I doubt the GarageBand defaults are gonna cut it.
Comment: Okay, so "drum machine" is more inclusive than "beat grid" it appears.  I'll consider Logic Pro X once I have the funding.  I'm really just starting out.  For now I'll look for a beat grid I can somehow integrate with GarageBand.
Answer: Another tip in GarageBand is to set up the Drummer to play something close to what you want. Then you can copy that track that it creates into a new Software Instrument Track. You can then edit that as you would like. This gives you a lot of flexibility, but also gives you a nice full sound to start off with.


What's the advantage of using short wings rather than long wings?

Question: To clarify the question, I mean the type of wing used on a Concorde or a fighter jet, vs a glider's long and thin ones. What is the aerodynamic reason for using a short wing when the plane is faster?
Answer: Another reason to have shorter wings on high-speed or maneuverable aircraft deals with the aircraft's aspect ratio, which is the ratio between its length to is breadth/chord. Longer wings (high aspect) bend more under load, and may twist, which causes structural issues. Additionally, aircraft with shorter wings (low aspect) can roll much quicker. This means that a fighter jet with short wings may roll at rates up to 720 degrees/second while a large airliner or cargo plane may roll at 15-60 degrees per second.
A third reason is parasitic drag. From the linked wikipedia article above:

While high aspect wings create less induced drag, they have greater parasitic drag, (drag due to shape, frontal area, and surface friction). This is because, for an equal wing area, the average chord (length in the direction of wind travel over the wing) is smaller. Due to the effects of Reynolds number, the value of the section drag coefficient is an inverse logarithmic function of the characteristic length of the surface, which means that, even if two wings of the same area are flying at equal speeds and equal angles of attack, the section drag coefficient is slightly higher on the wing with the smaller chord. However, this variation is very small when compared to the variation in induced drag with changing wingspan.
  For example, the section drag coefficient $c_d$; of a NACA 23012 airfoil (at typical lift coefficients) is inversely proportional to chord length to the power 0.129:
   $$ c_d \varpropto \frac{1}{(\text{chord})^{0.129}}.$$

Since parasite drag increases with airspeed, and high aspect wings have higher parasite drag, it makes sense for high-speed aircraft to have the wing that creates less drag at high speeds, and the slower aircraft to have the wing that creates less induced drag. You can see this in a simple graphic of the drag curves:

(Since the induced drag is lower at high speeds anyway, there is little point in minimizing that, rather minimize the type of drag that is a much larger factor at high speeds)
Answer: At low airspeed, the aerodynamics of long thin wings are great. The longer and thinner, the lower the induced drag (the drag inherent in creating lift, very dominant at low speeds). However, aero requirements always seem to be contrary to structures requirements. Savings in aerodynamics are often offset by increased weight of structures, and a balance needs to be struck for the best fuel economy.

The wing shape is very dependent on the maximum design speed of the craft, roughly as follows:

Subsonic < Mach 0.6: long, thin and straight please. Induced drag is the dominant design factor.
High subsonic < M0.85: friction drag becomes more dominant, induced drag is less due to higher speed, and compressibility effects start introducing quite a bit of extra drag. Wing sweep is introduced. A long, thin, swept wing creates a high amount of torsion, heavier structure etc, so unfortunately we need to keep the wings a bit shorter and stubbier. New materials and wing profiles enable longer and thinner wings again with less of a weight penalty.
Transsonic between M 0.85 and M1.2: Compressibility is such a dominant factor that the area rule is much more important in reducing drag than the wing shape. Whichever wing shape fits the area rule is best. But fuel economy in this speed region is always questionable, either slow down like all pax planes or speed up like Concorde.
Supersonic > M 1.2. Compressibility drag is all dominant, and now we want to mainly limit this form of drag. Induced drag is of no concern anymore. A very good way of limiting shock wave drag is to make sure that all of the wing stays within the shock cone streaming from the nose tip: within this cone, airspeed is lower than outside the cone. Even for military planes where fuel economy is not the dominant design factor, the performance penalty of having the wing stick out of the shock cone is considerable.

Source
Answer: You may want to take a look at this and this but generally it has to do with the fact that many things change at super sonic speeds mainly

The primary advantage of the delta wing is that, with a large enough
  angle of rearward sweep, the wing's leading edge will not contact the
  shock wave boundary formed at the nose of the fuselage as the speed of
  the aircraft approaches and exceeds transonic to supersonic speed.
Comment: @EwenW. - simply, where the wings sweep to the rear (the wingtips are aft of the wing root)
Comment: The opposite of http://en.wikipedia.org/wiki/Forward-swept_wing
Comment: Thanks! Though I'm not so sure what a "rearward sweep" refers to.
Answer: Short wing means less structural weight. But an airplane needs an optimum wing surface area (optimum for its weight, in other words the wing it needs to generate enough lift for the size of the airplane). So for the same lift, a shorter wing would be lighter, but study have shown that lift is not generated on the full span of the wing, so a short wing would not be efficient. A longer wing is much more efficient (generate more lift for its surface) but at the expense of weight (you need a beefier structure to maintain the integrity of the wing, so there is a sweet spot in between)
Answer: A high-aspect ratio wing is not only for slow flight.  lt work fine at high airspeeds too (so long as we are still well below the transonic range), as long as the wing is kept small enough to keep the wing loading appropriately high.  However, such a wing would already be flying at a rather high angle-of-attack even in wings-level flight at cruise speed, so there would be little room for pulling "extra" G's for radical maneuvering, without stalling the wing.
In the below-transonic speed range, high-aspect ratio wing are the most efficient wings possible at their optimum angle-of-attack, but they lose efficiency rapidly as the angle-of-attack is decreased below that optimum angle, compared to wings with lower aspect ratio.
A "Reno racer" with wings shaped like a sailplane's wings would either
A) stall (or at least enter the high-drag "mush" zone near the stall) while trying to "pull G's" during the turns (if the wings were small enough to be optimized for the straight portions of the race), or
B) suffer from much more parasite drag and therefore much more total drag than a lower aspect ratio wing on the straight portions of the race (if the wing were large enough to be optimized for "pulling G's" during the turns.)


Tammy a connu Tex ______ ses études à Lyon. Would you put "depuis" or "pendant" in the blank? Why?

Question: The correct answer is pendant but that doesn't make sense because Tammy still knows Tex in the present. So wouldn't this be considered an ongoing present action? So depuis should be the answer; not pendant, right?
Answer: There are 2 points about this sentence :

About tenses

Here, we are talking about an event (implied by the use of the "passé composé"). You meet someone once, then you know him/her. So here, you refer to the moment you met him, not about the fact you know him at the present.
To use depuis, which continues in the present, you would have to change the tense, and so use present, in order to say you are still in touch with him :

Tammy connait Tex depuis sa 3ème année de Fac à Lyon.

We would say "Tammy connaissait Tex depuis..." if we mean Tammy doesn't know Tex anymore, or if one of them is gone.

 2. About the moment description
To use depuis, you have to talk about a precise moment, implicitly saying it was a short period of time:

Tammy connait Tex depuis sa 3ème année de Fac à Lyon.

Note that saying "depuis ses études" sounds weird... Maybe because of the pronom possessif "ses". We would better say "depuis la Fac" for instance, which talks about the same period of life.
Whereas pendant is used when you talk about a period, and implicitly saying it lasted a certain time (it was not brieve).
Here, it is not precise enough to be used with depuis.
Note you could use depuis with those kind of elements :

depuis la maternelle, depuis le lycée, depuis qu'on est enfants, depuis la nuit des temps, depuis qu'on a travaillé ensemble...

Conclusion

Tammy a connu Tex pendant ses études à Lyon

is the correct answer.
Comment: Most of you answer is correct and helpful. But it is wrong to claim that *passé composé* is used for brieve actions. *Il a écrit son autobiographie en trois ans* is a perfectly natural sentence. The difference between *passé composé* and *imparfait*, is event vs context. (Which is an event better intuition to understand the use of tenses here.)
Comment: Thank you @StéphaneGimenez, I edited answer not to claim this :)
Answer: The ongoing present action would be expressed by using present tense:

Tammy connait Tex depuis ses études à Lyon

This implies she still "knows" him, in the sense they're still seeing each other now.
In your sentence, this currently going relation isn't implied... She might have known (actually, met) him during her studies, but it might be they didn't see each other since then. Note that this formulation (the one from your question) might aswell be used to describe an ongoing relation, the context being there helping to understand if it's still ongoing or not :

J'ai connu ma femme/mon meilleur ami pendant mes études à Lyon


When brewing a chocolate stout, should the cacao nibs be added in the boil, the secondary, or both?

Question: When using cacao nibs to brew a chocolate stout, should they be added in the boil (if so, when?), in the secondary fermenter, or both? Is there a better ingredient to add to produce the chocolate flavor?
Answer: Most "Chocolate" stouts get their flavor from a combination of roasted malts - chocolate malt, pale chocolate malt or coffee malt. There are delicious exceptions, like Young's Double Chocolate Stout.
Nibs are dehusked, roasted cacao seeds. They are high in fat (relatively tasteless cocoa butter), which does not add much flavor and which might cause problems with head retention if you put nibs in the boil. Cocoa powder is a much more concentrated source of chocolate flavor and comes without the fat. However, it is a more highly-processed product, which some people would like to avoid.
If using nibs, you could crack them and soak them in vodka to sanitize and extract any alcohol-soluble flavors, then dump the nibs plus vodka into the secondary.
If using cocoa powder, then you could add it towards the end of the boil. Beware clumping, because it is very powdery.
Comment: I already added the 8oz in the boil. My plan was to soak the other 8oz in vodka (as you described), but only for a half hour or so to sanitize. I was then going to discard most of the vodka and only add the nibs. Is it better to add the vodka too?
Comment: You probably won't get much flavor extraction into the vodka after half an hour, so it won't hurt to leave the vodka behind.
Comment: Awesome, thanks!


What is the difference between temperature and thermodynamic temperature?

Question: My course book says that kelvin is the unit of thermodynamic temperature, then what is the difference between temperature and thermodynamic temperature.
Answer: Temperature is more of a relative notion--heat flows from higher temperature to lower temperature, but that's about it. The zero in a temperature scale is meaningless; it is an arbitrary convention. Usually, we measure temperature in Celsius, Fahrenheit, Rankine, etc (note that Kelvin measures temperature as well--but it also measures thermodynamic temperature)
Thermodynamic temperature is such that zero temperature is absolute zero (unlike Celsius, where -273.15°C is absolute zero). It is related to the energy (specifically the kinetic energy) of the molecules of a substance-- for example, in a gas, kinetic energy per molecule is $\frac12k_BT$ (rotational energy, etc can be obtained if you know the type of molecule--but temperature is principally a measure of kinetic energy). It also has strong ties with entropy.
We generally don't use "temperature" in thermodynamics, thermodynamic temperature is more convenient. Temperature is only useful in equations involving temperature difference--whereas equations involving the absolute value of temperature (Arrhenius equation in kinetics, entropy, Maxwell distribution equation, etc) demand thermodynamic temperature.
Comment: Whenever you use a temperature in any calculation rather than a temperature difference, you have to use Kelvin! (Or another thermodynamic temperature scale.) If you are working out chemical reaction rates, for example (Which aren't normally thought of as thermodynamics but kinetics.)
Comment: Do these equations involve general gas equation? @ManishEarth
Answer: There is no difference between temperature and thermodynamic temperature. Wikipedia has a nice writeup. The book likely uses the adjective in order to differentiate from ill-defined conventional connotations. Temperature is an ensemble property, e.g., an ideal gas has an average energy of $\frac{1}{2}k_BT$. Outside of equilibrium, temperature is ill-defined.
Comment: https://en.wikipedia.org/wiki/Thermodynamic_temperature is the absolute temperature
https://en.wikipedia.org/wiki/Temperature is the ensemble propery

Heat radiation is based on fourth power the absolute Temperature (e.g. Kelvin), here you cant take Celcius or Farenheit (without convertion)

Also the thermal energy is approximate proportional to the absolute Temperature, not the relative Temperture. So there is a difference.
Answer: "Thermodynamic temperature" is a misnomer.  It arises from the misinterpretation of the double adjective used in English.  For example, if we say "Jane is a Chinese History Professor," does this mean that "Jane is a Professor of History who happens to be Chinese" or that "Jane is  Professor of Chinese History"?  For the case of temperature, does "thermodynamic temperature scale" mean "thermodynamic scale of temperature" or "scale of thermodynamic temperature"?  It appears that when the kelvin was introduced into the SI, the former was intended but the physical quantity was (falsely) interpreted as the latter.


How to start customizing linux?

Question: I've heard that Android is based on linux (or unix?). That means, engineers at google modified linux code to run on android phones or tablets. I would like to become those engineers someday. Where should I start? Should I start looking at embedded linux?
Answer: Actually google did more writing an app platform / virtual machine system to run on top of linux than they did modifying linux. They basically just used it as a base to build off of, they hardly had to touch it.
As for your question, just start doing things. Get yourself some linux distros, install them on your computers or in VM's, learn your way around them, then start poking at custom platforms like embeded once you already know the ropes. Find some devices to hack, code up some projects of your own, then find some open source projects to lend a hand with. Along the way you'll figure out how to answer your own question.
Comment: // Great answer. I guess there is no short way. Just installed ubuntu :)
Answer: A good place to start would be to learn to compile the Linux Kernel.  Go to www.kernel.org and start downloading the git versions and try to compile them first.  Dont install them yet!  Just learning to build the kernel will get you going for sure.

How to start customizing linux?