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Coronary CT angiography: image quality, diagnostic accuracy, and potential for radiation dose reduction using a novel iterative image reconstruction technique - comparison with traditional filtered back projection
International Nuclear Information System (INIS)
To compare image noise, image quality and diagnostic accuracy of coronary CT angiography (cCTA) using a novel iterative reconstruction algorithm versus traditional filtered back projection (FBP) and to estimate the potential for radiation dose savings. Sixty five consecutive patients (48 men; 59.3 ± 7.7 years) prospectively underwent cCTA and coronary catheter angiography (CCA). Full radiation dose data, using all projections, were reconstructed with FBP. To simulate image acquisition at half the radiation dose, 50% of the projections were discarded from the raw data. The resulting half-dose data were reconstructed with sinogram-affirmed iterative reconstruction (SAFIRE). Full-dose FBP and half-dose iterative reconstructions were compared with regard to image noise and image quality, and their respective accuracy for stenosis detection was compared against CCA. Compared with full-dose FBP, half-dose iterative reconstructions showed significantly (p = 0.001 - p = 0.025) lower image noise and slightly higher image quality. Iterative reconstruction improved the accuracy of stenosis detection compared with FBP (per-patient: accuracy 96.9% vs. 93.8%, sensitivity 100% vs. 100%, specificity 94.6% vs. 89.2%, NPV 100% vs. 100%, PPV 93.3% vs. 87.5%). Iterative reconstruction significantly reduces image noise without loss of diagnostic information and holds the potential for substantial radiation dose reduction from cCTA. (orig.)
Wiener filter for filtered back projection in digital breast tomosynthesis
Conventional filtered back projection (FBP) reconstruction for digital breast tomosynthesis (DBT) can suffer from a low signal to noise ratio. Because of the strong amplification by the reconstruction filters (ramp, apodization and slice thickness), noise at high spatial frequencies can be greatly increased. Image enhancement by Wiener filtering is investigated as a possible method to improve image quality. A neighborhood wavelet coefficient window technique is used to estimate the noise content of projection images and a Wiener filter is applied to the projection images. The neighborhood wavelet coefficient window is a non-linear technique, which may cause the Wiener filters estimated before and after the application of the reconstruction filters to be different. Image quality of a FBP reconstruction with and without Wiener filtering is investigated using a Fourier-based observer detectability metric ( d' ) for evaluation. Simulations of tomosynthesis are performed in both homogeneous and anatomic textured backgrounds containing lowcontrast masses or small microcalcifications. Initial results suggest that improvements in detectability can be achieved when the Wiener filter is applied, especially when the Wiener filter is estimated for the reconstruction filtered projections.
Wang, Xinying; Mainprize, James G.; Wu, Gang; Yaffe, Martin J.
Filtered back-projection algorithm for Compton telescopes
A method for the conversion of Compton camera data into a 2D image of the incident-radiation flux on the celestial sphere includes detecting coincident gamma radiation flux arriving from various directions of a 2-sphere. These events are mapped by back-projection onto the 2-sphere to produce a convolution integral that is subsequently stereographically projected onto a 2-plane to produce a second convolution integral which is deconvolved by the Fourier method to produce an image that is then projected onto the 2-sphere.
Gunter, Donald L. (Lisle, IL)
A novel denoising method based on Radon transform and filtered back-projection reconstruction algorithm
A novel denoising method based on Radon transform and filtered back-projection (FBP) image reconstruction algorithm was proposed. This method can be considered as a special mean filter on projection line, which is different from most of the traditional filters operated on adjacent templates that could bring serious blurs to images. The details of images processed by the proposed method can be preserved relatively complete and the denoising effect is satisfactory. To verify the denoising effect of the proposed method, the simulation was designed and carried out, and the image evaluation parameters were applied to analyze the denoising effect and the detail-preserving ability quantitatively. For further understanding of the proposed method, the basic denoising principle of this method was analyzed. Noise points and information points can be distinguished: the attenuation velocity of gray scale of noise points is faster than that of information points, which was verified by the experiment. The results of different parameters in the proposed method were compared and analyzed. Several kinds of traditional filters were compared with the proposed method, and the result shows that the proposed method is better than the traditional filters in the aspects of both denoising effect and detail-preserving ability. Apart from this, the proposed method is not particular about the kind of noise; therefore, it is a powerful method to deal with atypical noise, uncertain noise, and mixed noises.
Qu, Hong-yan; Xu, Feng; Hu, Xiao-fang; Wang, Luo-bin; Zhao, Jing; Zhang, Zhong
A reconstruction algorithm for coherent scatter computed tomography based on filtered back-projection
International Nuclear Information System (INIS)
Coherent scatter computed tomography (CSCT) is a reconstructive x-ray imaging technique that yields the spatially resolved coherent-scatter form factor of the investigated object. Reconstruction from coherently scattered x-rays is commonly done using algebraic reconstruction techniques (ART). In this paper, we propose an alternative approach based on filtered back-projection. For the first time, a three-dimensional (3D) filtered back-projection technique using curved 3D back-projection lines is applied to two-dimensional coherent scatter projection data. The proposed algorithm is tested with simulated projection data as well as with projection data acquired with a demonstrator setup similar to a multi-line CT scanner geometry. While yielding comparable image quality as ART reconstruction, the modified 3D filtered back-projection algorithm is about two orders of magnitude faster. In contrast to iterative reconstruction schemes, it has the advantage that subfield-of-view reconstruction becomes feasible. This allows a selective reconstruction of the coherent-scatter form factor for a region of interest. The proposed modified 3D filtered back-projection algorithm is a powerful reconstruction technique to be implemented in a CSCT scanning system. This method gives coherent scatter CT the potential of becoming a competitive modality for medical imaging or nondestructive testing
Monte Carlo evaluation of the Filtered Back Projection method for image reconstruction in proton computed tomography
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In this paper the use of the Filtered Back Projection (FBP) Algorithm, in order to reconstruct tomographic images using the high energy (200-250 MeV) proton beams, is investigated. The algorithm has been studied in detail with a Monte Carlo approach and image quality has been analysed and compared with the total absorbed dose. A proton Computed Tomography (pCT) apparatus, developed by our group, has been fully simulated to exploit the power of the Geant4 Monte Carlo toolkit. From the simulation of the apparatus, a set of tomographic images of a test phantom has been reconstructed using the FBP at different absorbed dose values. The images have been evaluated in terms of homogeneity, noise, contrast, spatial and density resolution.
The Comparison of Iterative and Filtered Back Projection Method for Gamma-ray CT
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There are two categories for an image reconstruction, the transform based reconstruction and the iterative reconstruction technique. The transform based reconstruction is based on an inverse radon transform theory. Filtered Back Projection (FBP) method is a frequently used algorithm based on radon model. In FBP, it is assumed that the measured data consist of line integrals of the object distribution. Iterative reconstruction technique is the method in which the estimated image is progressively refined in a repetitive calculation. For X-ray CT, FBP has been the most powerful technique because it has the sufficient number of total ray-sums. Unlike the X-ray CT, there are situations where it is not possible to measure a large number of projections for the industrial gamma-ray CT. In addition to aforementioned factors, there are many different characteristics between the gamma-ray and Xray. To get a precise image from gamma-ray CT, the adequate image reconstruction algorithm should be adopted. To evaluate the algorithm suitable for gamma ray CT, comparison of iterative and FBP method result from the gamma-ray CT is introduced
Comparison of Maximum Entropy and Filtered Back-Projection Methods to Reconstruct Rapid-Scan EPR Images
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Reconstruction of two-dimensional images by filtered back-projection (FBP) and by the maximum entropy method (MEM) was compared for spectral-spatial EPR images with differing signal-to-noise ratios. Experimental projections were recorded using direct-detected rapid scans in the presence of a series of magnetic field gradients. The slow-scan absorption lineshapes were calculated by Fourier deconvolution. A Hamming filter was used in conjunction with FBP, but not for MEM. Imperfections in real ...
Comparison of adaptive statistical iterative and filtered back projection reconstruction techniques in brain CT
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Purpose: To compare image quality and visualization of normal structures and lesions in brain computed tomography (CT) with adaptive statistical iterative reconstruction (ASIR) and filtered back projection (FBP) reconstruction techniques in different X-ray tube current–time products. Materials and methods: In this IRB-approved prospective study, forty patients (nineteen men, twenty-one women; mean age 69.5 ± 11.2 years) received brain scan at different tube current–time products (300 and 200 mAs) in 64-section multi-detector CT (GE, Discovery CT750 HD). Images were reconstructed with FBP and four levels of ASIR-FBP blending. Two radiologists (please note that our hospital is renowned for its geriatric medicine department, and these two radiologists are more experienced in chronic cerebral vascular disease than in neoplastic disease, so this research did not contain cerebral tumors but as a discussion) assessed all the reconstructed images for visibility of normal structures, lesion conspicuity, image contrast and diagnostic confidence in a blinded and randomized manner. Volume CT dose index (CTDIvol) and dose-length product (DLP) were recorded. All the data were analyzed by using SPSS 13.0 statistical analysis software. Results: There was no statistically significant difference between the image qualities at 200 mAs with 50% ASIR blending technique and 300 mAs with FBP technique (p > .05). While between the image qualities at 200 mAs with FBP and 300 mAs with FBP technique a statistically significant difference (p < .05) was found. Conclusion: ASIR provided same image quality and diagnostic ability in brain imaging with greater than 30% dose reduction compared with FBP reconstruction technique
Comparison of adaptive statistical iterative and filtered back projection reconstruction techniques in brain CT
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Purpose: To compare image quality and visualization of normal structures and lesions in brain computed tomography (CT) with adaptive statistical iterative reconstruction (ASIR) and filtered back projection (FBP) reconstruction techniques in different X-ray tube current–time products. Materials and methods: In this IRB-approved prospective study, forty patients (nineteen men, twenty-one women; mean age 69.5 ± 11.2 years) received brain scan at different tube current–time products (300 and 200 mAs) in 64-section multi-detector CT (GE, Discovery CT750 HD). Images were reconstructed with FBP and four levels of ASIR-FBP blending. Two radiologists (please note that our hospital is renowned for its geriatric medicine department, and these two radiologists are more experienced in chronic cerebral vascular disease than in neoplastic disease, so this research did not contain cerebral tumors but as a discussion) assessed all the reconstructed images for visibility of normal structures, lesion conspicuity, image contrast and diagnostic confidence in a blinded and randomized manner. Volume CT dose index (CTDI{sub vol}) and dose-length product (DLP) were recorded. All the data were analyzed by using SPSS 13.0 statistical analysis software. Results: There was no statistically significant difference between the image qualities at 200 mAs with 50% ASIR blending technique and 300 mAs with FBP technique (p > .05). While between the image qualities at 200 mAs with FBP and 300 mAs with FBP technique a statistically significant difference (p < .05) was found. Conclusion: ASIR provided same image quality and diagnostic ability in brain imaging with greater than 30% dose reduction compared with FBP reconstruction technique.
Ren, Qingguo, E-mail: firstname.lastname@example.com [Department of Radiology, Hua Dong Hospital of Fudan University, Shanghai 200040 (China); Dewan, Sheilesh Kumar, E-mail: email@example.com [Department of Geriatrics, Hua Dong Hospital of Fudan University, Shanghai 200040 (China); Li, Ming, E-mail: email@example.com [Department of Radiology, Hua Dong Hospital of Fudan University, Shanghai 200040 (China); Li, Jianying, E-mail: firstname.lastname@example.com [CT Imaging Research Center, GE Healthcare China, Beijing (China); Mao, Dingbiao, E-mail: firstname.lastname@example.com [Department of Radiology, Hua Dong Hospital of Fudan University, Shanghai 200040 (China); Wang, Zhenglei, E-mail: email@example.com [Department of Radiology, Shanghai Electricity Hospital, Shanghai 200050 (China); Hua, Yanqing, E-mail: firstname.lastname@example.com [Department of Radiology, Hua Dong Hospital of Fudan University, Shanghai 200040 (China)
The influence of filtered back-projection and iterative reconstruction on partial volume correction in PET
International Nuclear Information System (INIS)
Aim: We assess the influence of the reconstruction algorithms [OS-EM for the iterative one vs. a filtered back-projection in Fourier space (DiFT)] on partial volume correction in PET employing a fully 3D 3-compartment MR based PV-correction algorithm. The gray matter voxels in the PET image - after removal of the white matter and cerebrospinal fluid contribution - are corrected voxel-by-voxel using the image resolution. Material, methods: Phantom measurements and one healthy human brain FDG study were carried out. For the OSEM reconstruction, a combination of iteration steps and subset numbers (It/Sub) was used, whereby in case of no-convergence the image resolution had to be fitted. The results from the DiFT reconstruction were equivalent to those obtained from the OSEM reconstruction with 10/32 combination for objects with widespread activity concentration. For the sphere phantom, the mean recovery based on the actual values achieved 99.2%±1.8 for all spheres and all reconstruction modes at It/Sub combinations (except for 2/8). In case of the Hoffman 3D brain phantom the mean recovery of the cortical regions was 101%±1.2 (the increase based on the uncorrected values: 35.5%±1.5), while the subcortical regions reached a mean recovery of 80% with an increase of 43.9%±2.5. For the human data, an increase of the metabolized values of several cortical regions ranged between 42% and 48% independent form the reconstruction mode. Conclusions: Our data show that the 3-compartment fully 3-D MR based PV-correction is sensitive to the choice of reconstruction algorithms and to the parameter choice. They indicate that despite improved spatial resolution, the use of the iterative reconstruction algorithm for PV-correction results in similar recovery factors when compared to a correction using DiFT reconstruction, insofar the image resolution values are fitted at the It/Sub combinations. (orig.)
Study on an improved filtered back-projection image reconstruction algorithm combined with wavelet denoising
In the process of medical imaging (MI) reconstruction, filtering of original projection data is a key step to overcome artifact of the reconstructed image. Although some classical filters can be used into FBP algorithm, some drawbacks limit its application in practice, especially for the data polluted by non-stationary random noises. To overcome the shortcomings of these traditional filtering, an improved FBP combined with a shift-invariant wavelet threshold denoising algorithm is proposed in this paper. In the experiments, the reconstructed effects were compared between the improved algorithm, classical soft and hard threshold denoising methods. Experimental results illustrated that the reconstruction effect of improved FBP algorithm is better than that of others. In addition, two evaluation standards, i.e. mean-square error (MSE), peak-to-peak signal-noise ratio (PSNR) were used to compare the results of different algorithms. It was found that the reconstructed effects of the improved FBP combined with shift-invariant wavelet hard threshold function based on RL filter is better than others. Therefore, this improved FBP algorithm has potential value in the medical imaging.
Ren, Zhong; Liu, Guodong; Huang, Zhen
Single Image Super-Resolution VIA Iterative Back Projection Based Canny Edge Detection and a Gabor Filter Prior
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Full Text Available The Iterative back-projection (IBP is a classical super-resolution method with low computational complexity that can be applied in real time applications. This paper presents an effective novel single image super resolution approach to recover a high resolution image from a single low resolution input image. The approach is based on an Iterative back projection (IBP method combined with the Canny Edge Detection and Gabor Filter to recover high frequency information. This method is applied on different natural gray images and compared with different existing image super resolution approaches. Simulation results show that the proposed algorithms can more accurately enlarge the low resolution image than previous approaches. Proposed algorithm increases the MSSIM and the PSNR and decreases MSE compared to other existing algorithms and also improves visual quality of enlarged images.
Rujul R Makwana
Imaging reconstruction based on improved wavelet denoising combined with parallel-beam filtered back-projection algorithm
The image reconstruction is a key step in medical imaging (MI) and its algorithm's performance determinates the quality and resolution of reconstructed image. Although some algorithms have been used, filter back-projection (FBP) algorithm is still the classical and commonly-used algorithm in clinical MI. In FBP algorithm, filtering of original projection data is a key step in order to overcome artifact of the reconstructed image. Since simple using of classical filters, such as Shepp-Logan (SL), Ram-Lak (RL) filter have some drawbacks and limitations in practice, especially for the projection data polluted by non-stationary random noises. So, an improved wavelet denoising combined with parallel-beam FBP algorithm is used to enhance the quality of reconstructed image in this paper. In the experiments, the reconstructed effects were compared between the improved wavelet denoising and others (directly FBP, mean filter combined FBP and median filter combined FBP method). To determine the optimum reconstruction effect, different algorithms, and different wavelet bases combined with three filters were respectively test. Experimental results show the reconstruction effect of improved FBP algorithm is better than that of others. Comparing the results of different algorithms based on two evaluation standards i.e. mean-square error (MSE), peak-to-peak signal-noise ratio (PSNR), it was found that the reconstructed effects of the improved FBP based on db2 and Hanning filter at decomposition scale 2 was best, its MSE value was less and the PSNR value was higher than others. Therefore, this improved FBP algorithm has potential value in the medical imaging.
Ren, Zhong; Liu, Guodong; Huang, Zhen
Comparison of the clinical value of a method of iterative reconstruction with that of filtered back-projection in SPECT of the liver
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We have tested an iterative reconstruction procedure against the usual filtered back-projection in 14 patients with SPECT-examinations of various liver diseases. The aim of the examinations was to assess the presence of liver tumors in most cases. Further indications were Budd-Chiari syndromes and a liver malconfiguration in one case. Three of six haemangiomas and both liver metastases were better delineated with the iterative method, in one patient the haemangioma was visible only with this method. An irregular pattern after filtered back-projection led to misinterpretation as multiple metastases in another patient in whom there was no irregularity after iteration. Diagnostic improvement was not reached in the Budd-Chiari syndromes or in an atypical liver configuration, with a more homogeneous pattern after iteration however. The iterative reconstruction procedure was superior to the filtered back-projection method in the detection of small focal liver diseases. (orig.)
Motion-compensated and gated cone beam filtered back-projection for 3-D rotational X-ray angiography.
This paper presents a method to reconstruct moving objects from cone beam X-ray projections acquired during a single rotational run using a given motion vector field. The method is applicable to voxel driven cone-beam filtered back-projection reconstruction approaches. Here, a formulation based on the algorithm of Feldkamp, Davis, and Kress (FDK) is presented. The motion correction is applied during the back-projection step by shifting the voxel to be reconstructed according to the motion vector field. The method is applied to three-dimensional (3-D) rotational X-ray angiography. Projections from a beating coronary heart phantom are simulated. Motion-compensated reconstructions with varying accuracy of the applied motion field are carried out for a late diastolic heart phase and compared to the reconstruction obtained with the standard FDK-method from projections of the corresponding motion-free model in the same heart phase. Furthermore, gated reconstructions are calculated by weighting the projections according to their cardiac phase without using a motion vector field. Different gating window widths are applied, and the reconstructions are compared. Using the correct motion field with the motion-compensated reconstruction, the image quality of the standard reconstruction from the corresponding motion-free coronary model can almost be recovered. The reconstructed image quality stays acceptable if the accuracy of the motion field sampling points is better than 1 mm. The gated reconstructions with a window width of 15%-20% of the cardiac cycle lead to superior results compared to nearest neighbor gating, especially for histogram based visualization and analysis. The motion-compensated reconstructions provide sharp images of the coronaries far surpassing the image quality of gated reconstructions. PMID:16827490
Schäfer, Dirk; Borgert, Jörn; Rasche, Volker; Grass, Michael
Filtered back projection method for corn-beam X-ray CT
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X-ray computed tomography can provide clearly the internal structure of the cross-section of the human-body as the image of X-ray absorption coefficient. Though conventional CT provides only a transversal image of the body or organs of interest, three-dimensional structures of organs are needed for clinical diagnosis or radiation therapy planning. In this research we studied the reconstructing algorithm for divergent X-ray CT which can provide 3-D image with one rotational scan. As the results we have found a new deblurred filter function. The evaluation of the algorithm has been done by computer simulation. The fairly good reconstructing results have been achieved. (author)
Chest computed tomography using iterative reconstruction vs filtered back projection (Part 1): evaluation of image noise reduction in 32 patients
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To assess noise reduction achievable with an iterative reconstruction algorithm. 32 consecutive chest CT angiograms were reconstructed with regular filtered back projection (FBP) (Group 1) and an iterative reconstruction technique (IRIS) with 3 (Group 2a) and 5 (Group 2b) iterations. Objective image noise was significantly reduced in Group 2a and Group 2b compared with FBP (p < 0.0001). There was a significant reduction in the level of subjective image noise in Group 2a compared with Group 1 images (p < 0.003), further reinforced on Group 2b images (Group 2b vs Group 1; p < 0.0001) (Group 2b vs Group 2a; p = 0.0006). The overall image quality scores significantly improved on Group 2a images compared with Group 1 images (p = 0.0081) and on Group 2b images compared with Group 2a images (p < 0.0001). Comparative analysis of individual CT features of mild lung infiltration showed improved conspicuity of ground glass attenuation (p < 0.0001), ill-defined micronodules (p = 0.0351) and emphysematous lesions (p < 0.0001) on Group 2a images, further improved on Group 2b images for ground glass attenuation (p < 0.0001), and emphysematous lesions (p = 0.0087). Compared with regular FBP, iterative reconstructions enable significant reduction of image noise without loss of diagnostic information, thus having the potential to decrease radiation dose during chest CT examinations. (orig.)
Why do commercial CT scanners still employ traditional, filtered back-projection for image reconstruction?
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Despite major advances in x-ray sources, detector arrays, gantry mechanical design and especially computer performance, one component of computed tomography (CT) scanners has remained virtually constant for the past 25 years—the reconstruction algorithm. Fundamental advances have been made in the solution of inverse problems, especially tomographic reconstruction, but these works have not been translated into clinical and related practice. The reasons are not obvious and seldom discussed. This review seeks to examine the reasons for this discrepancy and provides recommendations on how it can be resolved. We take the example of field of compressive sensing (CS), summarizing this new area of research from the eyes of practical medical physicists and explaining the disconnection between theoretical and application-oriented research. Using a few issues specific to CT, which engineers have addressed in very specific ways, we try to distill the mathematical problem underlying each of these issues with the hope of demonstrating that there are interesting mathematical problems of general importance that can result from in depth analysis of specific issues. We then sketch some unconventional CT-imaging designs that have the potential to impact on CT applications, if the link between applied mathematicians and engineers/physicists were stronger. Finally, we close with some observations on how the link could be strengthened. There is, we believe, an important opportunity to rapidly improve the performance of CT and related tomographic imaging techniques by addressing these issues. (topical review)
Investigation of the quantitative accuracy of 3D iterative reconstruction algorithms in comparison to filtered back projection method: a phantom study
Introduction: Single-Photon Emission Computed Tomography (SPECT) is used to measure and quantify radiopharmaceutical distribution within the body. The accuracy of quantification depends on acquisition parameters and reconstruction algorithms. Until recently, most SPECT images were constructed using Filtered Back Projection techniques with no attenuation or scatter corrections. The introduction of 3-D Iterative Reconstruction algorithms with the availability of both computed tomography (CT)-based attenuation correction and scatter correction may provide for more accurate measurement of radiotracer bio-distribution. The effect of attenuation and scatter corrections on accuracy of SPECT measurements is well researched. It has been suggested that the combination of CT-based attenuation correction and scatter correction can allow for more accurate quantification of radiopharmaceutical distribution in SPECT studies (Bushberg et al., 2012). However, The effect of respiratory induced cardiac motion on SPECT images acquired using higher resolution algorithms such 3-D iterative reconstruction with attenuation and scatter corrections has not been investigated. Aims: To investigate the quantitative accuracy of 3D iterative reconstruction algorithms in comparison to filtered back projection (FBP) methods implemented on cardiac SPECT/CT imaging with and without CT-attenuation and scatter corrections. Also to investigate the effects of respiratory induced cardiac motion on myocardium perfusion quantification. Lastly, to present a comparison of spatial resolution for FBP and ordered subset expectation maximization (OSEM) Flash 3D together with and without respiratory induced motion, and with and without attenuation and scatter correction. Methods: This study was performed on a Siemens Symbia T16 SPECT/CT system using clinical acquisition protocols. Respiratory induced cardiac motion was simulated by imaging a cardiac phantom insert whilst moving it using a respiratory motion motor inducing cyclical elliptical motion of the apex of the cardiac insert. Results: Our analyses revealed that the use of the Flash 3-D reconstruction algorithm without scatter or attenuation correction has improved Spatial Resolution by 30% relative to FBP. Reduction in Spatial Resolution due to respiratory induced motion was 12% and 38% for FBP and Flash 3-D respectively. The implementation of scatter correction has resulted in a reduction in resolution by up to 6%. The application of CT-based attenuation correction has resulted in 13% and 26% reduction in spatial resolution for SPECT images reconstructed using FBP and Flash 3-D algorithms respectively. Conclusion: We conclude that iterative reconstruction (Flash-3D) provides significant improvement in image spatial resolution, however as a result the effects of respiratory induced motion have become more evident and correction of this is required before the full potential of these algorithms can be realised for myocardial perfusion imaging. Attenuation and scatter correction can improve image contrast, but may have significant detrimental effect on spatial resolution.
Abuhadi, Nouf; Bradley, David; Katarey, Dev; Podolyak, Zsolt; Sassi, Salem
FDG-PET standardized uptake values in normal anatomical structures using iterative reconstruction segmented attenuation correction and filtered back-projection
International Nuclear Information System (INIS)
Filtered back-projection (FBP) is the most commonly used reconstruction method for PET images, which are usually noisy. The iterative reconstruction segmented attenuation correction (IRSAC) algorithm improves image quality without reducing image resolution. The standardized uptake value (SUV) is the most clinically utilized quantitative parameter of [fluorine-18]fluoro-2-deoxy-d-glucose (FDG) accumulation. The objective of this study was to obtain a table of SUVs for several normal anatomical structures from both routinely used FBP and IRSAC reconstructed images and to compare the data obtained with both methods. Twenty whole-body PET scans performed in consecutive patients with proven or suspected non-small cell lung cancer were retrospectively analyzed. Images were processed using both IRSAC and FBP algorithms. Nonquantitative or gaussian filters were used to smooth the transmission scan when using FBP or IRSAC algorithms, respectively. A phantom study was performed to evaluate the effect of different filters on SUV. Maximum and average SUVs (SUVmax and SUVavg) were calculated in 28 normal anatomical structures and in one pathological site. The phantom study showed that the use of a nonquantitative smoothing filter in the transmission scan results in a less accurate quantification and in a 20% underestimation of the actual measurement. Most anatomical structures were identified in all patients using the IRSAC images. On average, SUVavg and SUVmax measured on IRSAC images using a gaussian filter in the transmission scan were respectively 20% and 8% higher than the SUVs calculated from conventional FBP images. Scatterplots of the data values showed an overall strong relationship between IRSAC and FBP SUVs. Individual scatterplots of each site demonstrated a weaker relationship for lower SUVs and for SUVmax than for higher SUVs and SUVavg. A set of reference values was obtained for SUVmax and SUVavg of normal anatomical structures, calculated with both IRSAC and FBP image reconstruction algorithms. The use of IRSAC and a gaussian filter for the transmission scan seems to give more accurate SUVs than are obtained from conventional FBP images using a nonquantitative filter for the transmission scan. (orig.)
Comparison between human and model observer performance in low-contrast detection tasks in CT images: application to images reconstructed with filtered back projection and iterative algorithms.
Objective: To compare low-contrast detectability (LCDet) performance between a model [non-pre-whitening matched filter with an eye filter (NPWE)] and human observers in CT images reconstructed with filtered back projection (FBP) and iterative [adaptive iterative dose reduction three-dimensional (AIDR 3D; Toshiba Medical Systems, Zoetermeer, Netherlands)] algorithms. Methods: Images of the Catphan® phantom (Phantom Laboratories, New York, NY) were acquired with Aquilion ONE™ 320-detector row CT (Toshiba Medical Systems, Tokyo, Japan) at five tube current levels (20-500?mA range) and reconstructed with FBP and AIDR 3D. Samples containing either low-contrast objects (diameters, 2-15?mm) or background were extracted and analysed by the NPWE model and four human observers in a two-alternative forced choice detection task study. Proportion correct (PC) values were obtained for each analysed object and used to compare human and model observer performances. An efficiency factor (?) was calculated to normalize NPWE to human results. Results: Human and NPWE model PC values (normalized by the efficiency, ??=?0.44) were highly correlated for the whole dose range. The Pearson's product-moment correlation coefficients (95% confidence interval) between human and NPWE were 0.984 (0.972-0.991) for AIDR 3D and 0.984 (0.971-0.991) for FBP, respectively. Bland-Altman plots based on PC results showed excellent agreement between human and NPWE [mean absolute difference 0.5?±?0.4%; range of differences (-4.7%, 5.6%)]. Conclusion: The NPWE model observer can predict human performance in LCDet tasks in phantom CT images reconstructed with FBP and AIDR 3D algorithms at different dose levels. Advances in knowledge: Quantitative assessment of LCDet in CT can accurately be performed using software based on a model observer. PMID:24837275
Hernandez-Giron, I; Calzado, A; Geleijns, J; Joemai, R M S; Veldkamp, W J H
Quantitative analysis of emphysema and airway measurements according to iterative reconstruction algorithms: comparison of filtered back projection, adaptive statistical iterative reconstruction and model-based iterative reconstruction
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To evaluate filtered back projection (FBP) and two iterative reconstruction (IR) algorithms and their effects on the quantitative analysis of lung parenchyma and airway measurements on computed tomography (CT) images. Low-dose chest CT obtained in 281 adult patients were reconstructed using three algorithms: FBP, adaptive statistical IR (ASIR) and model-based IR (MBIR). Measurements of each dataset were compared: total lung volume, emphysema index (EI), airway measurements of the lumen and wall area as well as average wall thickness. Accuracy of airway measurements of each algorithm was also evaluated using an airway phantom. EI using a threshold of -950 HU was significantly different among the three algorithms in decreasing order of FBP (2.30 %), ASIR (1.49 %) and MBIR (1.20 %) (P < 0.01). Wall thickness was also significantly different among the three algorithms with FBP (2.09 mm) demonstrating thicker walls than ASIR (2.00 mm) and MBIR (1.88 mm) (P < 0.01). Airway phantom analysis revealed that MBIR showed the most accurate value for airway measurements. The three algorithms presented different EIs and wall thicknesses, decreasing in the order of FBP, ASIR and MBIR. Thus, care should be taken in selecting the appropriate IR algorithm on quantitative analysis of the lung. (orig.)
Choo, Ji Yung [Seoul National University Medical Research Center, Department of Radiology, Seoul National University College of Medicine, and Institute of Radiation Medicine, Seoul (Korea, Republic of); Korea University Ansan Hospital, Ansan-si, Department of Radiology, Gyeonggi-do (Korea, Republic of); Goo, Jin Mo; Park, Chang Min; Park, Sang Joon [Seoul National University Medical Research Center, Department of Radiology, Seoul National University College of Medicine, and Institute of Radiation Medicine, Seoul (Korea, Republic of); Seoul National University, Cancer Research Institute, Seoul (Korea, Republic of); Lee, Chang Hyun; Shim, Mi-Suk [Seoul National University Medical Research Center, Department of Radiology, Seoul National University College of Medicine, and Institute of Radiation Medicine, Seoul (Korea, Republic of)
CT of the pancreas: comparison of image quality and pancreatic duct depiction among model-based iterative, adaptive statistical iterative, and filtered back projection reconstruction techniques.
The purpose of this study is to compare CT images of the pancreas reconstructed with model-based iterative reconstruction (MBIR), adaptive statistical iterative reconstruction (ASiR), and filtered back projection (FBP) techniques for image quality and pancreatic duct (PD) depiction. Data from 40 patients with contrast-enhanced abdominal CT [CTDIvol: 10.3 ± 3.0 (mGy)] during the late arterial phase were reconstructed with FBP, 40% ASiR-FBP blending, and MBIR. Two radiologists assessed the depiction of the main PD, image noise, and overall image quality using 5-point scale independently. Objective CT value and noise were measured in the pancreatic parenchyma, and the contrast-to-noise ratio (CNR) of the PD was calculated. The Friedman test and post-hoc multiple comparisons with Bonferroni test following one-way ANOVA were used for qualitative and quantitative assessment, respectively. For the subjective assessment, scores for MBIR were significantly higher than those for FBP and 40% ASiR (all P ASiR, and MBIR images (P > 0.05). Objective image noise was significantly lower and CNR of the PD was higher with MBIR than with FBP and 40% ASiR (all P ASiR. PMID:24496703
Lin, Xiao-Zhu; Machida, Haruhiko; Rt, Isao Tanaka; Rt, Rika Fukui; Ueno, Eiko; Chen, Ke-Min; Yan, Fu-Hua
Quantitative analysis of emphysema and airway measurements according to iterative reconstruction algorithms: comparison of filtered back projection, adaptive statistical iterative reconstruction and model-based iterative reconstruction
International Nuclear Information System (INIS)
To evaluate filtered back projection (FBP) and two iterative reconstruction (IR) algorithms and their effects on the quantitative analysis of lung parenchyma and airway measurements on computed tomography (CT) images. Low-dose chest CT obtained in 281 adult patients were reconstructed using three algorithms: FBP, adaptive statistical IR (ASIR) and model-based IR (MBIR). Measurements of each dataset were compared: total lung volume, emphysema index (EI), airway measurements of the lumen and wall area as well as average wall thickness. Accuracy of airway measurements of each algorithm was also evaluated using an airway phantom. EI using a threshold of -950 HU was significantly different among the three algorithms in decreasing order of FBP (2.30 %), ASIR (1.49 %) and MBIR (1.20 %) (P < 0.01). Wall thickness was also significantly different among the three algorithms with FBP (2.09 mm) demonstrating thicker walls than ASIR (2.00 mm) and MBIR (1.88 mm) (P < 0.01). Airway phantom analysis revealed that MBIR showed the most accurate value for airway measurements. The three algorithms presented different EIs and wall thicknesses, decreasing in the order of FBP, ASIR and MBIR. Thus, care should be taken in selecting the appropriate IR algorithm on quantitative analysis of the lung. (orig.)
Adaptive statistical iterative reconstruction versus filtered back projection in the same patient: 64 channel liver CT image quality and patient radiation dose
International Nuclear Information System (INIS)
To compare routine dose liver CT reconstructed with filtered back projection (FBP) versus low dose images reconstructed with FBP and adaptive statistical iterative reconstruction (ASIR). In this retrospective study, patients had a routine dose protocol reconstructed with FBP, and again within 17 months (median 6.1 months), had a low dose protocol reconstructed twice, with FBP and ASIR. These reconstructions were compared for noise, image quality, and radiation dose. Nineteen patients were included. (12 male, mean age 58). Noise was significantly lower in low dose images reconstructed with ASIR compared to routine dose images reconstructed with FBP (liver: p <.05, aorta: p < 0.001). Low dose FBP images were scored significantly lower for subjective image quality than low dose ASIR (2.1 ± 0.5, 3.2 ± 0.8, p < 0.001). There was no difference in subjective image quality scores between routine dose FBP images and low dose ASIR images (3.6 ± 0.5, 3.2 ± 0.8, NS).Radiation dose was 41% less for the low dose protocol (4.4 ± 2.4 mSv versus 7.5 ± 5.5 mSv, p < 0.05). Our initial results suggest low dose CT images reconstructed with ASIR may have lower measured noise, similar image quality, yet significantly less radiation dose compared with higher dose images reconstructed with FBP. (orig.)
Adaptive statistical iterative reconstruction versus filtered back projection in the same patient: 64 channel liver CT image quality and patient radiation dose
Energy Technology Data Exchange (ETDEWEB)
To compare routine dose liver CT reconstructed with filtered back projection (FBP) versus low dose images reconstructed with FBP and adaptive statistical iterative reconstruction (ASIR). In this retrospective study, patients had a routine dose protocol reconstructed with FBP, and again within 17 months (median 6.1 months), had a low dose protocol reconstructed twice, with FBP and ASIR. These reconstructions were compared for noise, image quality, and radiation dose. Nineteen patients were included. (12 male, mean age 58). Noise was significantly lower in low dose images reconstructed with ASIR compared to routine dose images reconstructed with FBP (liver: p <.05, aorta: p < 0.001). Low dose FBP images were scored significantly lower for subjective image quality than low dose ASIR (2.1 {+-} 0.5, 3.2 {+-} 0.8, p < 0.001). There was no difference in subjective image quality scores between routine dose FBP images and low dose ASIR images (3.6 {+-} 0.5, 3.2 {+-} 0.8, NS).Radiation dose was 41% less for the low dose protocol (4.4 {+-} 2.4 mSv versus 7.5 {+-} 5.5 mSv, p < 0.05). Our initial results suggest low dose CT images reconstructed with ASIR may have lower measured noise, similar image quality, yet significantly less radiation dose compared with higher dose images reconstructed with FBP. (orig.)
Mitsumori, Lee M.; Shuman, William P.; Busey, Janet M.; Kolokythas, Orpheus; Koprowicz, Kent M. [University of Washington School of Medicine, Department of Radiology, Seattle, WA (United States)
Standard dose versus low-dose abdominal and pelvic CT: Comparison between filtered back projection versus adaptive iterative dose reduction 3D
International Nuclear Information System (INIS)
Purpose: To compare the dose and image quality of a standard dose abdominal and pelvic CT with Filtered Back Projection (FBP) to low-dose CT with Adaptive Iterative Dose Reduction 3D (AIDR 3D). Materials and methods: We retrospectively examined the images of 21 patients in the portal phase of an abdominal and pelvic CT scan before and after implementation of AIDR 3D iterative reconstruction. The acquisition length, dose and evaluations of the image quality were compared between standard dose FBP images and low-dose images reconstructed with AIDR 3D and FBP using the Wilcoxon test. Results: The mean acquisition length was similar for both CT scans. There was a significant dose reduction of 49.5% with low-dose CT compared to standard dose CT (mean DLP of 451 mGy.cm versus 892 mGy.cm, P < 0.001). There were no differences in image quality scores between standard dose FBP and low-dose AIDR 3D images (4.6 ± 0.6 versus 4.4 ± 0.6 respectively, P = 0.147). Conclusion: AIDR 3D iterative reconstruction enables a significant reduction in dose of 49.5% to be achieved with abdominal CT scan compared to FBP, whilst maintaining equivalent image quality. (authors)
Does quantification of myocardial perfusion SPECT study differ while image reconstruction is carried out using iteration algorithm instead of filtered back-projection? - preliminary report
International Nuclear Information System (INIS)
The purpose of this study was to compare the performance of two reconstruction algorithms: conventional filtered back-projection (FBP) and an iterative algorithm -ITW- in quantitative analysis of myocardial perfusion SPECT studies. The defect size and defect severity were assessed on 99mTc - MIBI images reconstructed using both methods and estimation of sensitivity in the detection of perfusion deficits and myocardial viability were performed as well. The study group comprised 43 patients (38 men and 5 women) in the age of 40-73 years (mean 59 years). Heart perfusion scintigraphy was performed following an injection of 22 to 25 mCi 99mTc -MIBI for exercise and rest myocardial perfusion study. Images were reconstructed using FBP and ITW algorithms. Defect size (DS) was quantified by a threshold program and CEqual programme. Defect severity (nadir) was calculated as the ratio of minimal/maximum counts from bull's eye polar map. Coronary arteriography was performed in all patients. Defect size calculated by threshold method on resting images did not differ between reconstruction methods (p=0.61 for cut-off 50% and p = 0.24 for cut-off 60%); defect severity was higher on images reconstructed with ITW (CI0.95 = 2.4% + 5.2% of maximal counts). Sensitivity for detection of heart perfusion defects and estimation of myocardial viability were similar on images reconstructed by both algorithms. (author)
Local detection of prostate cancer by positron emission tomography with 2-fluorodeoxyglucose comparison of filtered back projection and iterative reconstruction with segmented attenuation correction
International Nuclear Information System (INIS)
To compare filtered back projection (FBP) and iterative reconstruction with segmented attenuation correction (IRSAC) in the local imaging of prostate cancer by positron emission tomography with 2-fluorodeoxyglucose (FDG-PET). 13 patients with primary (n=7) or recurrent (n=6) prostate cancer who had increased uptake in the prostate on FDG-PET performed without urinary catheterization, contemporaneous biopsy confirming the presence of active tumor in the prostate, were retrospectively identified. Two independent nuclear medicine physicians separately rated FBP and IRSAC images for visualization of prostatic activity on a 4-point scale. Results were compared using biopsy and cross-sectional imaging findings as the standard of reference. IRSAC images were significantly better that FBP in terms of visualization of prostatic activity in 12 of 13 patients, and were equivalent in 1 patient (p<0.001, Wilcoxon signed ranks test). In particular, 2 foci of tumor activity in 2 different patients seen on IRSAC images were not visible on FBP images. In 11 patients who had a gross tumor mass evident on cross-sectional imaging, there was good agreement between PET and cross-sectional anatomic imaging with respect to tumor localization. In selected patients, cancer can be imaged within the prostate using FDG-PET, and IRSAC is superior to FBP in image reconstruction for local tumor visualization
Chest computed tomography using iterative reconstruction vs filtered back projection (Part 2): image quality of low-dose CT examinations in 80 patients
International Nuclear Information System (INIS)
To evaluate the image quality of an iterative reconstruction algorithm (IRIS) in low-dose chest CT in comparison with standard-dose filtered back projection (FBP) CT. Eighty consecutive patients referred for a follow-up chest CT examination of the chest, underwent a low-dose CT examination (Group 2) in similar technical conditions to those of the initial examination, (Group 1) except for the milliamperage selection and the replacement of regular FBP reconstruction by iterative reconstructions using three (Group 2a) and five iterations (Group 2b). Despite a mean decrease of 35.5% in the dose-length-product, there was no statistically significant difference between Group 2a and Group 1 in the objective noise, signal-to-noise (SNR) and contrast-to-noise (CNR) ratios and distribution of the overall image quality scores. Compared to Group 1, objective image noise in Group 2b was significantly reduced with increased SNR and CNR and a trend towards improved image quality. Iterative reconstructions using three iterations provide similar image quality compared with the conventionally used FBP reconstruction at 35% less dose, thus enabling dose reduction without loss of diagnostic information. According to our preliminary results, even higher dose reductions than 35% may be feasible by using more than three iterations. (orig.)
The comparison of ordered subset expectation maximization and filtered back projection technique for RBC blood pool SPECT in detection of liver hemangioma
Energy Technology Data Exchange (ETDEWEB)
Odered subset expectation maximization (OSEM) is a new iterative reconstruction technique for tomographic images that can reduce the reconstruction time comparing with conventional iteration method. We adopted this method of RBC blood pool SPECT and tried to validate the usefulness of OSEM in detection of liver hemangioma comparing with filtered back projection (FBP). A 64 projection SPECT study was acquired over 360 .deg. C by dual-head cameras after the injection of 750MBq of {sup 99m}Tc-RBC. OSEM was performed with various condition of subset (1,2,4,8,16 and 32) and iteration number (1,2,4,8 and 16) to obtain the best set for lesion detection. OSEM underwent in 17 lesions of 15 patients with liver hemangioma and compared with FBP images. Two nuclear medicine physicians reviewed these results independently. Best set for images was 4 iteration and 16 subset. In general, OSEM revealed more homogeneous images than FBP. Eighty-eight percent (15/17) of OSEM images were superior or equal to FBP for anatomic resolution. According to the blind review of images 70.5% (12/17) of OSEM was better in contrast (4/17), anatomic detail (4/17) and both (2/17). Two small lesions were detected by OSEM only and another 2 small lesions were failed to depict in both methods. Remaining 3 lesions revealed no difference in image quality. OSEM can provide better image quality as well as better results in detection of liver hemangioma than conventional FBP technique.
Jeon, Tae Joo; Kim, Hee Joung; Bong, Jung Kyun; Lee, Jong Doo [College of Medicine, Yonsei Univ., Seoul (Korea, Republic of)
Impact of adaptive iterative dose reduction (AIDR) 3D on low-dose abdominal CT - Comparison with routine-dose CT using filtered back projection
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Background: While CT is widely used in medical practice, a substantial source of radiation exposure is associated with an increased lifetime risk of cancer. Therefore, concerns to dose reduction in CT examinations are increasing and an iterative reconstruction algorithm, which allow for dose reduction by compensating image noise in the image reconstruction, has been developed. Purpose: To investigate the performance of low-dose abdominal CT using adaptive iterative dose reduction 3D (AIDR 3D) compared to routine-dose CT using filtered back projection (FBP). Material and Methods: Fifty-eight patients underwent both routine-dose CT scans using FBP and low-dose CT scans using AIDR 3D in the abdomen. The image noise levels, signal-to-noise ratios (SNRs), and contrast-to-noise ratios (CNRs) of the aorta, portal vein, liver, and pancreas were measured and compared in both scans. Visual evaluations were performed. The volume CT dose index (CTDIvol) was measured. Results: Image noise levels on low-dose CT images using AIDR 3D were significantly lower than, or not significantly different from, routine-dose CT images using FBP in reviewing the data on the basis of all patients and the three BMI groups. SNRs and CNRs on low-dose CT images using AIDR 3D were significantly higher than, or not significantly different from, routine-dose CT images using FBP in reviewing the data on the basis of all patients and the three BMI groups. In visual evaluation of the images, there were no statistically significant differences between the scans in all organs independently of BMI. The average CTDIvol at routine-dose and low dose CT was 21.4 and 10.8 mGy, respectively. Conclusion: Low-dose abdominal CT using AIDR 3D allows for approximately 50 % reduction in radiation dose without a degradation of image quality compared to routine-dose CT using FBP independently of BMI.
Matsuki, Mitsuru; Murakami, Takamichi [Dept. of Radiology, Kinki Univ. School of Medicine, Osaka (Japan)], e-mail: firstname.lastname@example.com; Juri, Hiroshi; Yoshikawa, Shushi; Narumi, Yoshifumi [Dept. of Radiology, Osaka Medical Coll., Osaka (Japan)
Comparison of the ultra-low-dose Veo algorithm with the gold standard filtered back projection for detecting pulmonary asbestos-related conditions: a clinical observational study
Objectives Radiation delivered during CT is a major concern, especially for individuals undergoing repeated screening. We aimed to compare a new ultra-low-dose algorithm called Veo with the gold standard filtered back projection (FBP) for detecting pulmonary asbestos-related conditions. Setting University Hospital CHU G. Montpied, Clermont-Ferrand, France Participants Asbestos-exposed workers were recruited following referral to screening for asbestos-related conditions. Two acquisitions were performed on a 64-slice CT: the gold standard FBP followed by Veo reconstruction. Outcome measures Two radiologists independently assessed asbestos-related abnormalities, pulmonary nodules, radiation doses and image quality (noise). Results We included 27 asbestos-exposed workers (63.3±6.5?years with 11.9±9.7?years of asbestos exposure). We observed 297 pleural plaques in 20 participants (74%). All patients (100%) had pulmonary nodules, totalling 167 nodules. Detection rates did not differ for pleural plaques (Veo 87% vs FBP 97%, NS), pleural thickening (100% for both) and pulmonary nodules (80% for both). Interstitial abnormalities were depicted less frequently with Veo than FBP. False negative and false positive did not exceed 2.7%. Compared with FBP, Veo decreased the radiation dose up to 87% (Veo 0.23±0.07 vs FBP 1.83±0.88?mSv, p<0.001). The objective image noise also decreased with Veo as much as 23% and signal-to-noise ratio increased up to 33%. Conclusions A low-dose CT with Veo reconstruction substantially reduced radiation. Veo compared favourably with FBP in detecting pleural plaques, pleural thickening and pulmonary nodules. These results should be confirmed on a larger sample size before the use of Veo in clinical routine practice in asbestos-related conditions, especially regarding the low prevalence of interstitial abnormalities in this study. Trial registration number NCT01955018.
Tekath, Marielle; Dutheil, Frederic; Bellini, Romain; Roche, Antoine; Pereira, Bruno; Naughton, Geraldine; Chamoux, Alain; Michel, Jean-Luc
The comparison of ordered subset expectation maximization and filtered back projection technique for RBC blood pool SPECT in detection of liver hemangioma
International Nuclear Information System (INIS)
Odered subset expectation maximization (OSEM) is a new iterative reconstruction technique for tomographic images that can reduce the reconstruction time comparing with conventional iteration method. We adopted this method of RBC blood pool SPECT and tried to validate the usefulness of OSEM in detection of liver hemangioma comparing with filtered back projection (FBP). A 64 projection SPECT study was acquired over 360 .deg. C by dual-head cameras after the injection of 750MBq of 99mTc-RBC. OSEM was performed with various condition of subset (1,2,4,8,16 and 32) and iteration number (1,2,4,8 and 16) to obtain the best set for lesion detection. OSEM underwent in 17 lesions of 15 patients with liver hemangioma and compared with FBP images. Two nuclear medicine physicians reviewed these results independently. Best set for images was 4 iteration and 16 subset. In general, OSEM revealed more homogeneous images than FBP. Eighty-eight percent (15/17) of OSEM images were superior or equal to FBP for anatomic resolution. According to the blind review of images 70.5% (12/17) of OSEM was better in contrast (4/17), anatomic detail (4/17) and both (2/17). Two small lesions were detected by OSEM only and another 2 small lesions were failed to depict in both methods. Remaining 3 lesions revealed no difference in image quality. OSEM can provide better image quality as well as better results in detection of liver hemangioma than conventional FBP technique
Measurement of vascular wall attenuation: Comparison of CT angiography using model-based iterative reconstruction with standard filtered back-projection algorithm CT in vitro
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Objectives: To compare the performance of model-based iterative reconstruction (MBIR) with that of standard filtered back projection (FBP) for measuring vascular wall attenuation. Study design: After subjecting 9 vascular models (actual attenuation value of wall, 89 HU) with wall thickness of 0.5, 1.0, or 1.5 mm that we filled with contrast material of 275, 396, or 542 HU to scanning using 64-detector computed tomography (CT), we reconstructed images using MBIR and FBP (Bone, Detail kernels) and measured wall attenuation at the center of the wall for each model. We performed attenuation measurements for each model and additional supportive measurements by a differentiation curve. We analyzed statistics using analyzes of variance with repeated measures. Results: Using the Bone kernel, standard deviation of the measurement exceeded 30 HU in most conditions. In measurements at the wall center, the attenuation values obtained using MBIR were comparable to or significantly closer to the actual wall attenuation than those acquired using Detail kernel. Using differentiation curves, we could measure attenuation for models with walls of 1.0- or 1.5-mm thickness using MBIR but only those of 1.5-mm thickness using Detail kernel. We detected no significant differences among the attenuation values of the vascular walls of either thickness (MBIR, P = 0.1606) or among the 3 densities of intravascular contrast material (MBIR, P = 0.8185; Detail kernel, P = 0.0802). Conclusions: Compared with FBP, MBIR reduces both reconstruction blur and image noise simultaneously, facilitates recognition of vascular wall boundaries, and can improve accuracy in measuring wall attenuation.
Suzuki, Shigeru, E-mail: email@example.com [Department of Radiology, Saitama Red Cross Hospital, 8-3-33 kamiochiai, Chuo-ku, Saitama 338-0001 (Japan); Department of Radiology, Tokyo Women' s Medical University Medical Center East, 2-1-10 Nishiogu, Arakawa-ku, Tokyo 116-8567 (Japan); Machida, Haruhiko, E-mail: firstname.lastname@example.com [Department of Radiology, Tokyo Women' s Medical University Medical Center East, 2-1-10 Nishiogu, Arakawa-ku, Tokyo 116-8567 (Japan); Tanaka, Isao, E-mail: email@example.com [Department of Radiology, Tokyo Women' s Medical University Medical Center East, 2-1-10 Nishiogu, Arakawa-ku, Tokyo 116-8567 (Japan); Ueno, Eiko, E-mail: firstname.lastname@example.com [Department of Radiology, Tokyo Women' s Medical University Medical Center East, 2-1-10 Nishiogu, Arakawa-ku, Tokyo 116-8567 (Japan)
Measurement of vascular wall attenuation: Comparison of CT angiography using model-based iterative reconstruction with standard filtered back-projection algorithm CT in vitro
International Nuclear Information System (INIS)
Objectives: To compare the performance of model-based iterative reconstruction (MBIR) with that of standard filtered back projection (FBP) for measuring vascular wall attenuation. Study design: After subjecting 9 vascular models (actual attenuation value of wall, 89 HU) with wall thickness of 0.5, 1.0, or 1.5 mm that we filled with contrast material of 275, 396, or 542 HU to scanning using 64-detector computed tomography (CT), we reconstructed images using MBIR and FBP (Bone, Detail kernels) and measured wall attenuation at the center of the wall for each model. We performed attenuation measurements for each model and additional supportive measurements by a differentiation curve. We analyzed statistics using analyzes of variance with repeated measures. Results: Using the Bone kernel, standard deviation of the measurement exceeded 30 HU in most conditions. In measurements at the wall center, the attenuation values obtained using MBIR were comparable to or significantly closer to the actual wall attenuation than those acquired using Detail kernel. Using differentiation curves, we could measure attenuation for models with walls of 1.0- or 1.5-mm thickness using MBIR but only those of 1.5-mm thickness using Detail kernel. We detected no significant differences among the attenuation values of the vascular walls of either thickness (MBIR, P = 0.1606) or among the 3 densities of intravascular contrast material (MBIR, P = 0.8185; Detail kernel, P = 0.0802). Conclusions: Compared with FBP, MBIR reduces both reconstruction blur and image noise simultaneously, facilitates recognition of vascular wall boundaries, and can improve accuracy in measuring wall attenuation.
Image quality and radiation dose of low dose coronary CT angiography in obese patients: Sinogram affirmed iterative reconstruction versus filtered back projection
International Nuclear Information System (INIS)
Purpose: To investigate the image quality and radiation dose of low radiation dose CT coronary angiography (CTCA) using sinogram affirmed iterative reconstruction (SAFIRE) compared with standard dose CTCA using filtered back-projection (FBP) in obese patients. Materials and methods: Seventy-eight consecutive obese patients were randomized into two groups and scanned using a prospectively ECG-triggered step-and-shot (SAS) CTCA protocol on a dual-source CT scanner. Thirty-nine patients (protocol A) were examined using a routine radiation dose protocol at 120 kV and images were reconstructed with FBP (protocol A). Thirty-nine patients (protocol B) were examined using a low dose protocol at 100 kV and images were reconstructed with SAFIRE. Two blinded observers independently assessed the image quality of each coronary segment using a 4-point scale (1 = non-diagnostic, 4 = excellent) and measured the objective parameters image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). Radiation dose was calculated. Results: The coronary artery image quality scores, image noise, SNR and CNR were not significantly different between protocols A and B (all p > 0.05), with image quality scores of 3.51 ± 0.70 versus 3.55 ± 0.47, respectively. The effective radiation dose was significantly lower in protocol B (4.41 ± 0.83 mSv) than that in protocol A (8.83 ± 1.74 mSv, p < 0.01). Conclusion: Compared with standard dose CTCA using FBP, low dose CTCA using SAFIRE can maintain diagnostic image quality with 50% reduction of radiation dose.
Image quality and radiation dose of low dose coronary CT angiography in obese patients: Sinogram affirmed iterative reconstruction versus filtered back projection
Energy Technology Data Exchange (ETDEWEB)
Purpose: To investigate the image quality and radiation dose of low radiation dose CT coronary angiography (CTCA) using sinogram affirmed iterative reconstruction (SAFIRE) compared with standard dose CTCA using filtered back-projection (FBP) in obese patients. Materials and methods: Seventy-eight consecutive obese patients were randomized into two groups and scanned using a prospectively ECG-triggered step-and-shot (SAS) CTCA protocol on a dual-source CT scanner. Thirty-nine patients (protocol A) were examined using a routine radiation dose protocol at 120 kV and images were reconstructed with FBP (protocol A). Thirty-nine patients (protocol B) were examined using a low dose protocol at 100 kV and images were reconstructed with SAFIRE. Two blinded observers independently assessed the image quality of each coronary segment using a 4-point scale (1 = non-diagnostic, 4 = excellent) and measured the objective parameters image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). Radiation dose was calculated. Results: The coronary artery image quality scores, image noise, SNR and CNR were not significantly different between protocols A and B (all p > 0.05), with image quality scores of 3.51 {+-} 0.70 versus 3.55 {+-} 0.47, respectively. The effective radiation dose was significantly lower in protocol B (4.41 {+-} 0.83 mSv) than that in protocol A (8.83 {+-} 1.74 mSv, p < 0.01). Conclusion: Compared with standard dose CTCA using FBP, low dose CTCA using SAFIRE can maintain diagnostic image quality with 50% reduction of radiation dose.
Wang, Rui, E-mail: firstname.lastname@example.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Schoepf, U. Joseph, E-mail: email@example.com [Heart and Vascular Center, Medical University of South Carolina, Ashley River Tower, 25 Courtenay Drive, Charleston, SC 29425-2260 (United States); Wu, Runze, E-mail: email@example.com [Siemens Healthcare China, 7 Wangjing Zhonghuan Nanlu, 100102 Beijing (China); Reddy, Ryan P., E-mail: email@example.com [Heart and Vascular Center, Medical University of South Carolina, Ashley River Tower, 25 Courtenay Drive, Charleston, SC 29425-2260 (United States); Zhang, Chuanchen, E-mail: email@example.com [Department of Radiology, Liaocheng People Hospital, 252000 Shandong (China); Yu, Wei, E-mail: firstname.lastname@example.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Liu, Yi, E-mail: firstname.lastname@example.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Zhang, Zhaoqi, E-mail: email@example.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China)
Evaluation of iterative reconstruction (OSEM) versus filtered back-projection for the assessment of myocardial glucose uptake and myocardial perfusion using dynamic PET
International Nuclear Information System (INIS)
Iterative reconstruction methods based on ordered-subset expectation maximisation (OSEM) has replaced filtered backprojection (FBP) in many clinical settings owing to the superior image quality. Whether OSEM is as accurate as FBP in quantitative positron emission tomography (PET) is uncertain. We compared the accuracy of OSEM and FBP for regional myocardial 18F-FDG uptake and 13NH3 perfusion measurements in cardiac PET. Ten healthy volunteers were studied. Five underwent dynamic 18F-FDG PET during hyperinsulinaemic-euglycaemic clamp, and five underwent 13NH3 perfusion measurement during rest and adenosine-induced hyperaemia. Images were reconstructed using FBP and OSEM ± an 8-mm Gaussian post-reconstruction filter. Filtered and unfiltered images showed agreement between the reconstruction methods within ±2SD in Bland-Altman plots of Ki values. The use of a Gaussian filter resulted in a systematic underestimation of Ki in the filtered images of 11%. The mean deviation between the reconstruction methods for both unfiltered and filtered images was 1.3%. Agreement within ±2SD between the methods was demonstrated for perfusion rate constants up to 2.5 min-1, corresponding to a perfusion of 3.4 ml g-1 min-1. The mean deviation between the two methods for unfiltered data was 2.7%, and for filtered data, 5.3%. The 18F-FDG uptake rate constants showed excellent agreement between the two reconstruction methods. In the perfusion range up to 3.4 ml g-1 min-1, agreement between 13NH3 perfusion obtained with OSEM and FBP was acceptable. The use of OSEM for measurement of perfusion values higher than 3.4 ml g-1 min-1 requires further evaluation. (orig.)
Computed tomography of the cervical spine: comparison of image quality between a standard-dose and a low-dose protocol using filtered back-projection and iterative reconstruction
International Nuclear Information System (INIS)
To compare image quality of a standard-dose (SD) and a low-dose (LD) cervical spine CT protocol using filtered back-projection (FBP) and iterative reconstruction (IR). Forty patients investigated by cervical spine CT were prospectively randomised into two groups: SD (120 kVp, 275 mAs) and LD (120 kVp, 150 mAs), both applying automatic tube current modulation. Data were reconstructed using both FBP and sinogram-affirmed IR. Image noise, signal-to-noise (SNR) and contrast-to-noise (CNR) ratios were measured. Two radiologists independently and blindly assessed the following anatomical structures at C3-C4 and C6-C7 levels, using a four-point scale: intervertebral disc, content of neural foramina and dural sac, ligaments, soft tissues and vertebrae. They subsequently rated overall image quality using a ten-point scale. For both protocols and at each disc level, IR significantly decreased image noise and increased SNR and CNR, compared with FBP. SNR and CNR were statistically equivalent in LD-IR and SD-FBP protocols. Regardless of the dose and disc level, the qualitative scores with IR compared with FBP, and with LD-IR compared with SD-FBP, were significantly higher or not statistically different for intervertebral discs, neural foramina and ligaments, while significantly lower or not statistically different for soft tissues and vertebrae. The overall image quality scores were significantly higher with IR compared with FBP, and with LD-IR compared with SD-FBP. LD-IR cervical spine CT provides better image quality for intervertebral discs, neural foramina and ligaments, and worse image quality for soft tissues and vertebrae, compared with SD-FBP, while reducing radiation dose by approximately 40 %. (orig.)
Computed tomography of the cervical spine: comparison of image quality between a standard-dose and a low-dose protocol using filtered back-projection and iterative reconstruction
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To compare image quality of a standard-dose (SD) and a low-dose (LD) cervical spine CT protocol using filtered back-projection (FBP) and iterative reconstruction (IR). Forty patients investigated by cervical spine CT were prospectively randomised into two groups: SD (120 kVp, 275 mAs) and LD (120 kVp, 150 mAs), both applying automatic tube current modulation. Data were reconstructed using both FBP and sinogram-affirmed IR. Image noise, signal-to-noise (SNR) and contrast-to-noise (CNR) ratios were measured. Two radiologists independently and blindly assessed the following anatomical structures at C3-C4 and C6-C7 levels, using a four-point scale: intervertebral disc, content of neural foramina and dural sac, ligaments, soft tissues and vertebrae. They subsequently rated overall image quality using a ten-point scale. For both protocols and at each disc level, IR significantly decreased image noise and increased SNR and CNR, compared with FBP. SNR and CNR were statistically equivalent in LD-IR and SD-FBP protocols. Regardless of the dose and disc level, the qualitative scores with IR compared with FBP, and with LD-IR compared with SD-FBP, were significantly higher or not statistically different for intervertebral discs, neural foramina and ligaments, while significantly lower or not statistically different for soft tissues and vertebrae. The overall image quality scores were significantly higher with IR compared with FBP, and with LD-IR compared with SD-FBP. LD-IR cervical spine CT provides better image quality for intervertebral discs, neural foramina and ligaments, and worse image quality for soft tissues and vertebrae, compared with SD-FBP, while reducing radiation dose by approximately 40 %. (orig.)
Becce, Fabio [University of Lausanne, Department of Diagnostic and Interventional Radiology, Centre Hospitalier Universitaire Vaudois, Lausanne (Switzerland); Universite Catholique Louvain, Department of Radiology, Cliniques Universitaires Saint-Luc, Brussels (Belgium); Ben Salah, Yosr; Berg, Bruno C. vande; Lecouvet, Frederic E.; Omoumi, Patrick [Universite Catholique Louvain, Department of Radiology, Cliniques Universitaires Saint-Luc, Brussels (Belgium); Verdun, Francis R. [University of Lausanne, Institute of Radiation Physics, Centre Hospitalier Universitaire Vaudois, Lausanne (Switzerland); Meuli, Reto [University of Lausanne, Department of Diagnostic and Interventional Radiology, Centre Hospitalier Universitaire Vaudois, Lausanne (Switzerland)
Quantitative evaluation of calcium (content) in the coronary artery using hybrid iterative reconstruction (iDose) algorithm on low-dose 64-detector CT. Comparison of iDose and filtered back projection
International Nuclear Information System (INIS)
To evaluate the usefulness of hybrid iterative reconstruction (iDose) for quantification of calcium content in the coronary artery on 64-detector computed tomography (CT), an anthropomorphic cardiac CT phantom containing cylinders with known calcium content was scanned at tube current-time products of 15, 20, 25, and 50 mAs using 64-detector CT. The images obtained at 15, 20, 25, and 50 mAs were reconstructed using filtered back projection (FBP), and those at 15, 20, and 25 mAs were also reconstructed using iDose. Then the volume and mass of the calcium content in the cylinders were calculated and compared with the true values. The Agatston score was also evaluated. The Agatston score and mass of calcium obtained at 50 mAs using FBP were 656.92 and 159.91 mg, respectively. In contrast, those obtained at 25 mAs using iDose were 641.91 and 159.05 mg, respectively. No significant differences were found in the calcium measurements obtained using FBP and iDose. In addition, the Agatston score and mass of calcium obtained at 15 mAs and 20 mAs using iDose were not significantly different from those obtained at 25 mAs with iDose. By using iDose, accurate quantification of calcium in the coronary artery can be achieved at 15 mAs using 64-detector CT. The radiation dose can be significantly reduced in coronary artery calcium scoring without impairing the detection and quantification of coronary calcification. (author)
Reconstruction of CT images by the Bayes- back projection method
In the course of research on quantitative assay of non-destructive measurement of radioactive waste, the have developed a unique program based on the Bayesian theory for reconstruction of transmission computed tomography (TCT) image. The reconstruction of cross-section images in the CT technology usually employs the Filtered Back Projection method. The new imaging reconstruction program reported here is based on the Bayesian Back Projection method, and it has a function of iterative improvement images by every step of measurement. Namely, this method has the capability of prompt display of a cross-section image corresponding to each angled projection data from every measurement. Hence, it is possible to observe an improved cross-section view by reflecting each projection data in almost real time. From the basic theory of Baysian Back Projection method, it can be not only applied to CT types of 1st, 2nd, and 3rd generation. This reported deals with a reconstruction program of cross-section images in the CT of ...
Haruyama, M; Takase, M; Tobita, H
Fan beam and parallel beam projection and back-projection operators
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Expressions for the fan beam and parallel beam projection and back-projection operators are given along with an evaluation of the point source response for the back-projection operators. The back-projection operator for the fan beam geometry requires the superposition of projection data measured over 3600. Both the fan beam and parallel beam geometries have back-projection operators with point source responses which are proportional to 1/mod (r-r0), and thus two-dimensional Fourier filter techniques can be used to reconstruct transverse sections from fan beam and parallel beam projection data. The two-dimensional Fourier filter techniques may have the speed over other methods for reconstructing fan beam data, but the reconstructed image requires four times the core storage so that the convolution result of one period does not overlap the convolution result of the succeeding period when implementing the fast Fourier transform. 10 figures
Color back projection for fruit maturity evaluation
In general, fruits and vegetables such as tomatoes and dates are harvested before they fully ripen. After harvesting, they continue to ripen and their color changes. Color is a good indicator of fruit maturity. For example, tomatoes change color from dark green to light green and then pink, light red, and dark red. Assessing tomato maturity helps maximize its shelf life. Color is used to determine the length of time the tomatoes can be transported. Medjool dates change color from green to yellow, and the orange, light red and dark red. Assessing date maturity helps determine the length of drying process to help ripen the dates. Color evaluation is an important step in the processing and inventory control of fruits and vegetables that directly affects profitability. This paper presents an efficient color back projection and image processing technique that is designed specifically for real-time maturity evaluation of fruits. This color processing method requires very simple training procedure to obtain the frequencies of colors that appear in each maturity stage. This color statistics is used to back project colors to predefined color indexes. Fruit maturity is then evaluated by analyzing the reprojected color indexes. This method has been implemented and used for commercial production.
Zhang, Dong; Lee, Dah-Jye; Desai, Alok
Procedure and apparatus for back projection
International Nuclear Information System (INIS)
(1) The procedure is for back projection in the form of a tomographic picture of a member, characterised in that the strip pictures are written onto the signal plate by a conversion pick-up unit; and that to the address inputs of the pick-up unit voltages are applied that represent a rotating coordinate system. (2) Procedure following claim 1 characterised by the fact that the voltages are respectively applied as sawtooth waveform horizontal and vertical television deflections. (3) Procedure following claims 1 and 2, characterised that in order to correct the television deflection voltages for the effect of a fan shaped radiation beam, first one and then the other of the amplitudes is modulated. (G.C.)
Estimating brain network activity through back-projection of ICA components to GLM maps.
Independent component analysis (ICA) is a data-driven approach frequently used in neuroimaging to model functional brain networks. Despite ICA's increasing popularity, methods for replicating published ICA components across independent datasets have been underemphasized. Traditionally, the task-dependent activation of a component is evaluated by first back-projecting the component to a functional MRI (fMRI) dataset, then performing general linear modeling (GLM) on the resulting timecourse. We propose the alternative approach of back-projecting the component directly to univariate GLM results. Using a sample of 37 participants performing the Multi-Source Interference Task, we demonstrate these two approaches to yield identical results. Furthermore, while replicating an ICA component requires back-projection of component beta-values (?s), components are typically depicted only by t-scores. We show that while back-projection of component ?s and t-scores yielded highly correlated results (?=0.95), group-level statistics differed between the two methods. We conclude by stressing the importance of reporting ICA component ?s, rather than component t-scores, so that functional networks may be independently replicated across datasets. PMID:24513233
James, G Andrew; Tripathi, Shanti Prakash; Kilts, Clinton D
UV Fluorescence Photography of Works of Art : Replacing the Traditional UV Cut Filters with Interference Filters
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Full Text Available For many years filters like the Kodak Wratten E series, or the equivalent Schneider B+W 415, were used as standard UV cut filters, necessary to obtain good quality on UV Fluorescence photography. The only problem with the use of these filters is that, when they receive the UV radiation that they should remove, they present themselves an internal fluorescence as side effect, that usually reduce contrast and quality on the final image. This article presents the results of our experiences on using some innovative filters, that appeared available on the market in recent years, projected to adsorb UV radiation even more efficiently than with the mentioned above pigment based standard filters: the interference filters for UV rejection (and, usually, for IR rejection too manufactured using interference layers, that present better results than the pigment based filters. The only problem with interference filters type is that they are sensitive to the rays direction and, because of that, they are not adequate to wide-angle lenses. The internal fluorescence for three filters: the B+W 415 UV cut (equivalent to the Kodak Wratten 2E, pigment based, the B+W 486 UV IR cut (an interference type filter, used frequently on digital cameras to remove IR or UV and the Baader UVIR rejection filter (two versions of this interference filter were used had been tested and compared. The final quality of the UV fluorescence images seems to be of a superior quality when compared to the images obtained with classic filters.
Luís BRAVO PEREIRA
An improved back projection algorithm of ultrasound tomography
Binary logic back projection algorithm is improved in this work for the development of fast ultrasound tomography system with a better effect of image reconstruction. The new algorithm is characterized by an extra logical value `2' and dual-threshold processing of collected raw data. To compare with the original algorithm, a numerical simulation was conducted by the verification of COMSOL simulations formerly, and then a set of ultrasonic tomography system is established to perform the experiments of one, two and three cylindrical objects. The object images are reconstructed through the inversion of signals matrix acquired by the transducer array after a preconditioning, while the corresponding spatial imaging errors can obviously indicate that the improved back projection method can achieve modified inversion effect.
Xiaozhen, Chen; Mingxu, Su; Xiaoshu, Cai
An accelerated threshold-based back-projection algorithm for Compton camera image reconstruction
International Nuclear Information System (INIS)
Purpose: Compton camera imaging (CCI) systems are currently under investigation for radiotherapy dose reconstruction and verification. The ability of such a system to provide real-time images during dose delivery will be limited by the computational speed of the image reconstruction algorithm. In this work, the authors present a fast and simple method by which to generate an initial back-projected image from acquired CCI data, suitable for use in a filtered back-projection algorithm or as a starting point for iterative reconstruction algorithms, and compare its performance to the current state of the art. Methods: Each detector event in a CCI system describes a conical surface that includes the true point of origin of the detected photon. Numerical image reconstruction algorithms require, as a first step, the back-projection of each of these conical surfaces into an image space. The algorithm presented here first generates a solution matrix for each slice of the image space by solving the intersection of the conical surface with the image plane. Each element of the solution matrix is proportional to the distance of the corresponding voxel from the true intersection curve. A threshold function was developed to extract those pixels sufficiently close to the true intersection to generate a binary intersection curve. This process is repeated for each image plane for each CCI detector event, resulting in a three-dimensional back-projection image. The performance of this algorithm was tested against a marching algorithm known for speed and accuracy. Results: The threshold-based algorithm was found to be approximately four times faster than the current state of the art with minimal deficit to image quality, arising from the fact that a generically applicable threshold function cannot provide perfect results in all situations. The algorithm fails to extract a complete intersection curve in image slices near the detector surface for detector event cones having axes nearly parallel to the image plane. This effect decreases the sum of the image, thereby also affecting the mean, standard deviation, and SNR of the image. All back-projected events associated with a simulated point source intersected the voxel containing the source and the FWHM of the back-projected image was similar to that obtained from the marching method. Conclusions: The slight deficit to image quality observed with the threshold-based back-projection algorithm described here is outweighed by the 75% reduction in computation time. The implementation of this method requires the development of an optimum threshold function, which determines the overall accuracy of the method. This makes the algorithm well-suited to applications involving the reconstruction of many large images, where the time invested in threshold development is offset by the decreased image reconstruction time. Implemented in a parallel-computing environment, the threshold-based algorithm has the potential to provide real-time dose verification for radiation therapy.
A Multi-Scale Weighted Back Projection Imaging Technique for Ground Penetrating Radar Applications
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Full Text Available In this paper, we propose a new ground penetrating radar (GPR imaging technique based on multi-scale weighted back projection (BP processing. Firstly, the whole imaging region is discretized by large scale and low-resolution imaging result is obtained by using traditional BP imaging technique. Secondly, the potential targets regions (PTR are delineated from low-resolution imaging result by using intensity detection method. In the PTR, small scale discretization is implemented and higher resolution imaging result is obtained by using weighted BP imaging technique. A weight factor is designed by analyzing the statistical characteristics of scattering data on the time-delay curve. The above "discretization-imaging-PTR delineation" processing continues until the imaging resolution reaches the specified requirement. In the multi-scale imaging result, the resolution in other regions is not as high as that in PTR. This algorithm can get higher resolution imaging results with much lower computation compared with traditional BP imaging algorithm. The simulation of this algorithm is processed and experimental results validate the feasibility of this method.
Wentai Lei
Modified Kalman Filter-based Approach in Comparison with Traditional Speech Enhancement Algorithms from Adverse Noisy Environments
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Full Text Available The paper presents a new speech enhancement approach for a single channel speech enhancement in a noise environment. In this method speech is mixed with real-world noises from babble, car and street environments. In this paper we proposed modified Kalman method for effective speech enhancement. The proposed method is compared to the traditional Spectral Subtraction (SS, Wiener Filter (WF, Minimum Mean Square Error (MMSE and Wavelet based Filter (WAVELET. Experiments showed that the modified algorithm can give better SNR improvement and Subjective evaluation tests demonstrate significant improvement results over classical algorithms, when tested withspeech signal corrupted a posterior by various noises at different signal to noise ratios.
G. Ramesh Babu,
Comparison of back projection methods of determining earthquake rupture process in time and frequency domains
Back projection is a method to back project the seismic energy recorded in a seismic array back to the earthquake source region and determine the rupture process of a large earthquake. The method takes advantage of the coherence of seismic energy in a seismic array and is quick in determining some important properties of earthquake source. The method can be performed in both time and frequency domains. In time domain, the most conventional procedure is beam forming with some measures of suppressing the noise, such as the Nth root stacking, etc. In the frequency domain, the multiple signal classification method (MUSIC) estimates the direction of arrivals of multiple waves propagating through an array using the subspace method. The advantage of this method is the ability to study rupture properties at various frequencies and to resolve simultaneous arrivals making it suitable for detecting biliteral rupture of an earthquake source. We present a comparison of back projection results on some large earthquakes between the methods in time domain and frequency domain. The time-domain procedure produces an image that is smeared and exhibits some artifacts, although some enhancing stacking methods can at some extent alleviate the problem. On the other hand, the MUSIC method resolves clear multiple arrivals and provides higher resolution of rupture imaging.
Wang, W.; Wen, L.
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In this paper, we present Furhat - a back-projected human-like robot head using state-of-the art facial animation. Three experiments are presented where we investigate how the head might facilitate human - robot face-to-face interaction. First, we investigate how the animated lips increase the intelligibility of the spoken output, and compare this to an animated agent presented on a flat screen, as well as to a human face. Second, we investigate the accuracy of the perception of Furhat's...
Al Moubayed, Samer; Skantze, Gabriel; Beskow, Jonas
External force back-projective composition and globally deformable optimization for 3-D coronary artery reconstruction
The clinical value of the 3D reconstruction of a coronary artery is important for the diagnosis and intervention of cardiovascular diseases. This work proposes a method based on a deformable model for reconstructing coronary arteries from two monoplane angiographic images acquired from different angles. First, an external force back-projective composition model is developed to determine the external force, for which the force distributions in different views are back-projected to the 3D space and composited in the same coordinate system based on the perspective projection principle of x-ray imaging. The elasticity and bending forces are composited as an internal force to maintain the smoothness of the deformable curve. Second, the deformable curve evolves rapidly toward the true vascular centerlines in 3D space and angiographic images under the combination of internal and external forces. Third, densely matched correspondence among vessel centerlines is constructed using a curve alignment method. The bundle adjustment method is then utilized for the global optimization of the projection parameters and the 3D structures. The proposed method is validated on phantom data and routine angiographic images with consideration for space and re-projection image errors. Experimental results demonstrate the effectiveness and robustness of the proposed method for the reconstruction of coronary arteries from two monoplane angiographic images. The proposed method can achieve a mean space error of 0.564 mm and a mean re-projection error of 0.349 mm.
Yang, Jian; Cong, Weijian; Chen, Yang; Fan, Jingfan; Liu, Yue; Wang, Yongtian
[ART reconstruction from few views using bilateral-filtering iterative method].
An algebraic image reconstruction from few views using bilateral-filtering iterative method was proposed due to the problem of computed tomography insufficient data in the present study. In each iteration reconstruction, we first used algebraic reconstruction technique (ART) algorithm to reconstruct an image, ensuring the non-negativity of the reconstructed image at the same time, and then performed bilateral-filtering to the above-mentioned image. In order to improve reconstructed image quality and accelerate the convergence speed, we developed a modified bilateral-filtering method. Shepp-Logan simulation experiments and real CT projection data reconstructions showed the feasibility of the algorithm. The results showed that, compared with the traditional methods of filtered back projection (FBP), ART and GF-ART,the proposed method has a higher signal-to-noise ratio, and maintains more effectively the image edge information. PMID:23858736
Qi, Hongliang; Zhou, Linghong; Xu, Yuan; Hong, Hong; Lu, Wenting; Zhen, Xin
Acoustic Image Reconstruction from Adaptive Microphone Array Signals Using Back Projection
We propose a new technique for acoustic imaging that employs a back-projection algorithm to process signals from a static ultrasonic microphone array. To obtain the projection data for a target, we integrate the time distribution of received signal powers gained by pulse compression with the Radon transform of a sound field in polar coordinates. The proposed method is expected to improve angular resolution. In this paper, we describe the principle of this algorithm, explaining how it improves the resolution and performs better than conventional methods. Deconvolution is used to improve the quality of the images obtained. We have conducted computer simulations to verify the performance of the proposed algorithm. From these simulations, the angular resolution of the images achieved by the proposed technique was shown to be double that obtained by a conventional beamforming method. In our future work, we plan to conduct experiments with real environments and investigate the theoretical aspects of the proposed method more deeply.
Mizutani, Kyohei; Sugimoto, Masanori; Hashizume, Hiromichi
Rapid localization of bone fragments on surfaces using back-projection and hyperspectral imaging.
Manual localization of bone fragments on the ground or on complex surfaces in relation to accidents or criminal activity may be time-consuming and challenging. It is here investigated whether combining a near-infrared hyperspectral camera and chemometric modeling with false color back-projection can be used for rapid localization of bone fragments. The approach is noninvasive and highlights the spatial distribution of various compounds/properties to facilitate manual inspection of surfaces. Discriminant partial least squares regression is used to classify between bone and nonbone spectra from the hyperspectral camera. A predictive model (>95% prediction ability) is constructed from raw chicken bones mixed with stone, sand, leaves, moss, and wood. The model uses features in the near-infrared spectrum which may be selective for bones in general and is able to identify a wide variety of bones from different animals and contexts, including aged and weathered bone. PMID:24547958
Alsberg, Bjřrn K; Rosvold, Jřrgen
Measurement of population receptive fields in human early visual cortex using back-projection tomography.
Properties of human visual population receptive fields (pRFs) are currently estimated by performing measurements of visual stimulation using functional magnetic resonance imaging (fMRI), and then fitting the results using a predefined model shape for the pRF. Various models exist and different models may be appropriate under different circumstances, but the validity of the models has never been verified, suggesting the need for a model-free approach. Here, we demonstrate that pRFs can be directly reconstructed using a back-projection-tomography approach that requires no a priori model. The back-projection method involves sweeping thin contrast-defined bars across the visual field whose orientation and direction is rotated through 0°-180° in discrete increments. The measured fMRI time series within a cortical location can be approximated as a projection of the pRF along the long axis of the bar. The signals produced by a set of bar sweeps encircling the visual field form a sinogram. pRFs were reconstructed from these sinograms with a novel scheme that corrects for the blur introduced by the hemodynamic response and the stimulus-bar width. pRF positions agree well with the conventional model-based approach. Notably, a subset of the reconstructed pRFs shows significant asymmetry for both their excitatory and suppressive regions. Reconstructing pRFs using the tomographic approach is a fast, reliable, and accurate way to noninvasively estimate human pRF parameters and visual-field maps without the need for any a priori shape assumption. PMID:24453343
Greene, Clint A; Dumoulin, Serge O; Harvey, Ben M; Ress, David
Resolution Analysis of finite fault inversions: A back-projection approach.
The resolution of inverted source models of large earthquakes is controlled by frequency contents of "coherent" (or "useful") seismic observations and their spatial distribution. But it is difficult to distinguish whether some features consistent during different inversions are really required by data or a consequence of "prior" information, such as velocity structures, fault geometry, model parameterizations. Here, we investigate the model spatial resolution by first back projecting and stacking the data at the source regions and then analyzing the spatial- temporal variations of the focusing regions, which arbitrarily defined as the regions with 90% of the peak focusing amplitude. Our preliminary results indicated 1) The spatial-temporal resolution at a particularly direction is controlled by the region of directivity parameter [pcos(?)] within the seismic network, where p is the horizontal slowness from the hypocenter and ? is the difference between the station azimuth and this orientation. Therefore, the network aperture is more important than the number of stations. 2) Simple stacking method is a robust method to capture the asperities but the sizes of focusing regions are usually much larger than what data could resolve. By carefully weighting the data before the stacking could enhance the spatial resolution in a particular direction. 3) The results based on the teleseismic P waves of a local network usually surfers the trade-off between the source's spatial location and its rupture time. The resolution of the 2001 Kunlunshan earthquake and 2006 Kuril island earthquake will be investigated.
Ji, C.; Shao, G.
Direct aperture optimization using an inverse form of back-projection.
Direct aperture optimization (DAO) has been used to produce high dosimetric quality intensity-modulated radiotherapy (IMRT) treatment plans with fast treatment delivery by directly modeling the multileaf collimator segment shapes and weights. To improve plan quality and reduce treatment time for our in-house treatment planning system, we implemented a new DAO approach without using a global objective function (GFO). An index concept is introduced as an inverse form of back-projection used in the CT multiplicative algebraic reconstruction technique (MART). The index, introduced for IMRT optimization in this work, is analogous to the multiplicand in MART. The index is defined as the ratio of the optima over the current. It is assigned to each voxel and beamlet to optimize the fluence map. The indices for beamlets and segments are used to optimize multileaf collimator (MLC) segment shapes and segment weights, respectively. Preliminary data show that without sacrificing dosimetric quality, the implementation of the DAO reduced average IMRT treatment time from 13 min to 8 min for the prostate, and from 15 min to 9 min for the head and neck using our in-house treatment planning system PlanUNC. The DAO approach has also shown promise in optimizing rotational IMRT with burst mode in a head and neck test case. PMID:24710439
Zhu, Xiaofeng; Cullip, Timothy; Tracton, Gregg; Tang, Xiaoli; Lian, Jun; Dooley, John; Chang, Sha X
Iterative projection reconstruction of time-resolved images using highly-constrained back-projection (HYPR).
Highly-constrained back-projection (HYPR) is a technique for the reconstruction of sparse, highly-undersampled time-resolved image data. A novel iterative HYPR (I-HYPR) algorithm is presented and validated in computer simulations. The reconstruction method is then applied to cerebral perfusion MRI simulated as a radial acquisition and contrast-enhanced angiography of the head to assess feasibility in accelerating acquisitions requiring high temporal resolution and accurate representation of contrast kinetics. The I-HYPR algorithm is shown to be more robust than standard HYPR in these applications in which the sparsity condition is not met or in which quantitative information is required. Specifically, iterative reconstruction of undersampled perfusion and contrast-enhanced angiography data improved accuracy of the representation of contrast kinetics and increased the temporal separation of arterial and venous contrast kinetics. The I-HYPR reconstruction may have important diagnostic applications in settings requiring high temporal resolution and quantitative signal dynamics. Because I-HYPR allows relaxation of the sparsity requirements for the composite frame, the iterative reconstruction can enable novel acquisition strategies that independently optimize the quality of the composite and temporal resolution of the dynamic frames. PMID:18058939
O'Halloran, Rafael L; Wen, Zhifei; Holmes, James H; Fain, Sean B
Radiation dose reduction in time-resolved CT angiography using highly constrained back projection reconstruction
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Recently dynamic, time-resolved three-dimensional computed tomography angiography (CTA) has been introduced to the neurological imaging community. However, the radiation dose delivered to patients in time-resolved CTA protocol is a high and potential risk associated with the ionizing radiation dose. Thus, minimizing the radiation dose is highly desirable for time-resolved CTA. In order to reduce the radiation dose delivered during dynamic, contrast-enhanced CT applications, we introduce here the CT formulation of HighlY constrained back PRojection (HYPR) imaging. We explore the radiation dose reduction approaches of both acquiring a reduced number of projections for each image and lowering the tube current used during acquisition. We then apply HYPR image reconstruction to produce image sets at a reduced patient dose and with low image noise. Numerical phantom experiments and retrospective analysis of in vivo canine studies are used to assess the accuracy and quality of HYPR reduced dose image sets and validate our approach. Experimental results demonstrated that a factor of 6-8 times radiation dose reduction is possible when the HYPR algorithm is applied to time-resolved CTA exams.
Supanich, Mark; Tao Yinghua; Nett, Brian; Mistretta, Charles; Chen Guanghong [Department of Medical Physics, University of Wisconsin in Madison, 1111 Highland Avenue, Madison, WI, 53705 (United States); Pulfer, Kari; Turski, Patrick; Rowley, Howard [Department of Radiology, University of Wisconsin in Madison, 600 Highland Avenue, Madison, WI, 53792 (United States); Hsieh Jiang [GE Medical Systems, 300 N, Grandview Blvd., Waukesha, WI 53188 (United States)], E-mail: firstname.lastname@example.com
Radiation dose reduction in time-resolved CT angiography using highly constrained back projection reconstruction
Recently dynamic, time-resolved three-dimensional computed tomography angiography (CTA) has been introduced to the neurological imaging community. However, the radiation dose delivered to patients in time-resolved CTA protocol is a high and potential risk associated with the ionizing radiation dose. Thus, minimizing the radiation dose is highly desirable for time-resolved CTA. In order to reduce the radiation dose delivered during dynamic, contrast-enhanced CT applications, we introduce here the CT formulation of HighlY constrained back PRojection (HYPR) imaging. We explore the radiation dose reduction approaches of both acquiring a reduced number of projections for each image and lowering the tube current used during acquisition. We then apply HYPR image reconstruction to produce image sets at a reduced patient dose and with low image noise. Numerical phantom experiments and retrospective analysis of in vivo canine studies are used to assess the accuracy and quality of HYPR reduced dose image sets and validate our approach. Experimental results demonstrated that a factor of 6-8 times radiation dose reduction is possible when the HYPR algorithm is applied to time-resolved CTA exams.
Supanich, Mark; Tao, Yinghua; Nett, Brian; Pulfer, Kari; Hsieh, Jiang; Turski, Patrick; Mistretta, Charles; Rowley, Howard; Chen, Guang-Hong
A comparative study between matched and mis-matched projection/back projection pairs used with ASIRT reconstruction method
International Nuclear Information System (INIS)
For algebraic reconstruction techniques both forward and back projection operators are needed. The ability to perform accurate reconstruction relies fundamentally on the forward projection and back projection methods which are usually, the transpose of each other. Even though the mis-matched pairs may introduce additional errors during the iterative process, the usefulness of mis-matched projector/back projector pairs has been proved in image reconstruction. This work investigates the performance of matched and mis-matched reconstruction pairs using popular forward projectors and their transposes when used in reconstruction tasks with additive simultaneous iterative reconstruction techniques (ASIRT) in a parallel beam approach. Simulated noiseless phantoms are used to compare the performance of the investigated pairs in terms of the root mean squared errors (RMSE) which are calculated between reconstructed slices and the reference in different regions. Results show that mis-matched projection/back projection pairs can promise more accuracy of reconstructed images than matched ones. The forward projection operator performance seems independent of the choice of the back projection operator and vice versa.
Parathyroid scintigraphy - benefit of early and late SPECT with iterative reconstruction (IR) versus filtered back projection (FBP)
International Nuclear Information System (INIS)
Full text: The published literature is conflicting on the benefit of Parathyroid SPECT. This study evaluates the incremental benefit of SPECT over planar imaging, comparing both the timing of SPECT and the processing technique used. Over 1 year, patients referred for parathyroid scintigraphy were studied with conventional dual tracer and dual phase planar imaging using 50 MBq of Tc-99m-pertechnetate and 800 MBq of Tc-99m MIBI. SPECT was performed both after the initial and 2 hour planars, and processed using both PBP and IR. All studies were randomised and read as planar, planar+FBP then planar+FBP+IR for both early and late SPECT by 2 blinded readers. Focal abnormalities were scored on a 5 point scale, with scores of 4 and 5 being called positive. In cases of observer disagreement a third blinded reader was used. Surgical follow up was available in 16 of 33 patients. 2 were surgically non curative and excluded (including one probable scintigraphic mediastinal adenoma not located at surgery). Sensitivity and ROC analyses were performed to evaluate incremental benefit of FBP and IR SPECT over planars. No significant difference was found between Early and Late SPECT. ROC analysis of individual readers showed improved accuracy of SPECT over planars for one of the two readers. IR SPECT improves sensitivity without loss of specificity compared to planar imaging. Late SPECT shows no additional benefit. Copyright (2002) The Australian and New Zealand Society of Nuclear Medicine Inc
Importance of point-by-point back projection correction for isocentric motion in digital breast tomosynthesis: Relevance to morphology of structures such as microcalcifications
International Nuclear Information System (INIS)
Digital breast tomosynthesis is a three-dimensional imaging technique that provides an arbitrary set of reconstruction planes in the breast from a limited-angle series of projection images acquired while the x-ray tube moves. Traditional shift-and-add (SAA) tomosynthesis reconstruction is a common mathematical method to line up each projection image based on its shifting amount to generate reconstruction slices. With parallel-path geometry of tube motion, the path of the tube lies in a plane parallel to the plane of the detector. The traditional SAA algorithm gives shift amounts for each projection image calculated only along the direction of x-ray tube movement. However, with the partial isocentric motion of the x-ray tube in breast tomosynthesis, small objects such as microcalcifications appear blurred (for instance, about 1-4 pixels in blur for a microcalcification in a human breast) in traditional SAA images in the direction perpendicular to the direction of tube motion. Some digital breast tomosynthesis algorithms reported in the literature utilize a traditional one-dimensional SAA method that is not wholly suitable for isocentric motion. In this paper, a point-by-point back projection (BP) method is described and compared with traditional SAA for the important clinical task of evaluating morphology of small objects such as microcalcifications. Impulse responses at different three-dimensional locations with five different combinations of imaging acquisition parameters were investigated. Reconstruction images of microcalcifications in a human subject were also evaluated. Results showed that with traditional SAA and 45 deg. view angle of tube movement with respect to the detector, at the same height above the detector, the in-plane blur artifacts were obvious for objects farther away from x-ray source. In a human subject, the appearance of calcifications was blurred in the direction orthogonal to the tube motion with traditional SAA. With point-by-point BP, the appearance of calcifications was sharper. The point-by-point BP method demonstrated improved rendition of microcalcifications in the direction perpendicular to the tube motion direction. With wide angles or for imaging of larger breasts, this point-by-point BP rather than the traditional SAA should also be considered as the basis of further deblurring algorithms that work in conjunction with the BP method
Qualitative Evaluation of Filter Function in Brain SPECT
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Introduction: Filtering can greatly affect the quality of clinical images. Determining the best filter and the proper degree of smoothing can help to ensure the most accurate diagnosis. Methods: Forty five patient's data aquired during brain phantom SPECT studies were reconstructed using filtered back-projection technique. The ramp, Shepp-Logan, Cosine, Hamming, Hanning, Butterworth, Metz and Wiener filters were examined to find the optimum condition for each filter. For each slice image, 6...
Elham Raeisi; Hossein Rajabi; Mahmoud Reza Aghamiri; Ebrahim Hajizadeh; Shahram Seifollahi-Asl; Nahid Yaghobi; Seyed Hassan Firozabadi; Ahmad Bitarafan Rajabi
High-frequency seismic emission during Maule earthquake (Mw 8.8, 27/02/2010) inferred from high-resolution back-projection analysis of P waves
Since its first application on Sumatra-Andaman earthquake, back-projection analysis has been widely exploited to infer the time-evolution of the rupture fronts of mega-earthquakes. In this technique, selected seismic phases recorded at teleseismic distances by a network of sensors are shifted according to a possible source position and a velocity model, and a multichannel version of the cross-correlation function is estimated. In this way, the time-dependent map of the seismic energy emission in the source area can be inferred. We have back-projected the mainshock of Maule earthquake (Mw 8.8), which nucleated on 27/02/2010 in central Chile and is one of the largest earthquakes recorded in modern times. We have analyzed P phases filtered in the frequency range (0.4-3) Hz recorded by three seismic arrays located in US, Africa and Antarctica. Relative time shifts between sensors (inferred by maximizing the cross-correlation function) have been estimated with respect to a 1D global velocity model (ak135) and have been refined introducing two corrections, a static correction and a dynamic correction. The former is the time shift induced by local effects in the sensor area, whereas the latter is the correction associated with the source-sensor path and is mostly affected by medium properties in the source area. We have inferred these two corrections by analyzing the waveforms of 23 aftershocks and foreshocks with high magnitude (>5.3). In detail, static correction was chosen as the mean time shift averaged over all the events recorded by one station, while dynamic correction was the remaining part of the travel time after removing the 1D model travel time and the static correction. Moreover, dynamic corrections (and hence the complete travel times) have been interpolated over all the source area by Kriging, a spatial interpolation method. Results show that high-frequency seismic energy emission mostly occurs along the coastline with a general northward migration during the event. Specifically, in the first minute of the rupture process, the energy emission occurs southerly from or close to the epicenter. Afterwards, seismic emission moves northwards, with a gap with respect to the first emission zone, and a further northward migration occurs till the end of emission. Both the spatial gap of seismic emission and the northward migration are in line with the results of other studies in the same area, whereas we find a shallower emission area and different emission features in the zone close to the epicenter. Results for different frequency bands and the analysis of secondary maxima of energy emission are being investigated. In particular, we are shifting towards higher frequencies looking at the frequency bands (1-4) Hz and (2-8) Hz. The former band displays an emission pattern similar to that of (0.4-3) Hz, but with a sharper gap of about 50 Km; the latter band shows coherent arrivals only during the first 80 s, with a clear energy emission south of the epicenter at the onset of the event and preserving the northward migration afterwards.
Palo, Mauro; Tilmann, Frederik; Ehlert, Lutz; Krüger, Frank; Lange, Dietrich
Digital tomo-synthesis by inverse filtering
International Nuclear Information System (INIS)
This paper proposes a new reconstructing method for digital tomo-synthesis to reduce the undesired superimposition. It utilizes a 3-dimensional convolution process with the inverse filtering. Inverse filter transfer function was derived analytically from the impulse response function of the projection and back-projection process. Unstability of the inverse filtering process has been eliminated considering the localization of object information in the Fourier space. By the phantom experiment using conventional tomographic system, it has been shown that the proposed algorithm is able to reproduce the expected gray level on the slice. It can also reduce the blurred images from outside of focused slice. (author)
Back projection of applicator geometry in CT-base brachytherapy: correlation index for bladder dose and Foley's catheter balloon in CT-base treatment planning intracavitary brachytherapy for the carcinoma of cervix
International Nuclear Information System (INIS)
The present study will correlate, the bladder dose with Foley's catheter balloon dose by applying back projection technique for applicators' reconstruction and will find out the most suitable dose points of balloon for prediction of dose to the bladder
Imaging source slip distribution by the back-projection of P-wave amplitudes from strong-motion records: a case study for the 2010 Jiasian, Taiwan, earthquake
We propose an approach to imaging earthquake source rupture process by direct back-projection of local high-frequency (0.1-2.5 Hz) P-wave displacements from strong-motion records. A series of synthetic experiments are performed which demonstrate that our approach is capable of recovering the spatial-temporal distribution of the source slip with a good station coverage and a high average coherence value between the target and template waveforms. We demonstrate the effectiveness of our approach by applying it to image the slip distribution of an earthquake occurred on 2010 March 4, in Jiasian (Mw = 6.0 and ML = 6.4) in southern Taiwan. The resulting moment-rate amplitude images show that the source rupture initiated at the vicinity of the hypocentre, followed by a moderate moment-rate release to the southeast of the hypocentre and a subsequent upward propagation, and finally propagated in the northwest direction, in agreement with the distribution of aftershocks. The majority of the slip at 17-20 km depth occurred to the west of the hypocentre, in a general agreement with the slip distributions obtained from dislocation model and finite-fault inversions. Our modified back-projection approach relies on seismic waveforms with the considerations of a recent 3-D structure model, high average coherence value, station correction factor and simplified amplitude correction. It is computationally efficient and allows for near real-time determinations of source slip distributions after earthquakes using strong-motion records. A quick result for the rupture model can be used in the calculation of strong ground-motion, providing important, useful and timely information for seismic hazard mitigation.
Chao, Wei-An; Zhao, Li; Wu, Yih-Min; Lee, Shiann-Jong
Traditional folk media (such as folk theater, dance and textile arts) offer health program managers a potentially powerful method of reaching rural villagers. While modern mass media (such as radio, television, printed matter) may extend messages to larger audiences at lower cost per person reached, their dependence on centralized, urban facilities and staff and their need for uniform, fixed messages often make them less responsive to local situations and specific audience needs. Traditional media use local language and symbols in a format which is familiar, credible and accessible to rural villagers. To be truly appropriate, traditional media (like other technologies) must be adapted to the overall approach, message, and intended audience with which they are used. Integration with modern media may be successful but must be approached cautiously. Evaluation is critical both for adjusting the specific project and for better assessment of the net effectiveness of folk media communication strategies. With appropriate matching of a strategy's central components and thorough consideration of implemenatation and management issues (integration, training, evaluation, funding), traditional fold media can become an extremely effective means of communicating health information. This issue outlines the guidelines for use of traditional media in health communication activities, with special emphasis on live drama puppetry, song and dance, storytelling and proverbs, and pictures, PMID:12268713
GNF - Green Filter in Columbia
... Technology description Green filters have the advantage of being a low cost infrastructure, their operation and maintenance costs are also low and ...an alternative system for traditional wastewater treatment plants, green filters have the advantage of consuming no energy or chemical products. In addition of ... This filtering technique gathers all advantages of being environmentally friendly and provides efficient wastewater treatment. Associated Impacts Wildlife: Green ...
Energy Technology Data Exchange (ETDEWEB)
Efforts for improving the collection efficiency of air filters began with the HEPA (high efficiency particulate air) filter for clean rooms in the semiconductor industry. Now, a ULPA (ultra low penetration air) filter has come into being, capable of dealing with 0.1{mu}m-large particulates, and studies are under way for a super ULPA or others capable of dust collection on the nanometer scale. The method generally used for enhancing filter material efficiency increases the number of fibers by making them finer in diameter, but this method also increases pressure loss. An improved method increases the amount of filter material without changing the diameter, which increases the handling capacity provided the rate remains the same of the fine dust travelling through the filter. Improvement on the folding of filter material or the use of materials lower in pressure loss should also be used jointly with the above-said measures. The latest filter is only 1/4 of the conventional ones in size and weight, which is attributed to the success in collection efficiency improvement and pressure loss reduction. Although the air filter aims primarily to collect fine dust, studies are under way to apply it for the control of chemical substances and for the cleaning of air at residential houses (against ticks and pollen). Used filters are buried as is or after incineration and compaction, or cleaned for reuse, but reconsideration needs be made about these methods of disposal. 6 refs., 4 figs., 4 tabs.
Takahashi, K. [Nippon Muki Co. Ltd., Tokyo (Japan)
For an implicitly defined discrete system, a new algorithm for Kalman filtering is developed and an efficient numerical implementation scheme is proposed. Unlike the traditional explicit approach, the implicit filter can be readily applied to ill-conditioned systems and allows for generalization to descriptor systems. The implementation of the implicit filter depends on the solution of the congruence matrix equation (A1)(Px)(AT1) = Py. We develop a general iterative method for the solution of this equation, and prove necessary and sufficient conditions for convergence. It is shown that when the system matrices of an implicit system are sparse, the implicit Kalman filter requires significantly less computer time and storage to implement as compared to the traditional explicit Kalman filter. Simulation results are presented to illustrate and substantiate the theoretical developments.
Skliar, M.; Ramirez, W. F.
GMTI processing using back projection.
Energy Technology Data Exchange (ETDEWEB)
Backprojection has long been applied to SAR image formation. It has equal utility in forming the range-velocity maps for Ground Moving Target Indicator (GMTI) radar processing. In particular, it overcomes the problem of targets migrating through range resolution cells.
Doerry, Armin Walter
Digital Repository Infrastructure Vision for European Research (DRIVER)
Chinese dumplings such as Jiao Zi and Bao Zi are two of the popular traditional foods in Asia. They are usually made from wheat flour dough (rice flour or starch is sometimes used) that contains fillings. They can be steamed, boiled and fried and are consumed either as a main meal or dessert. As these tasty dumplings are easy to prepare, they have become one of Asia's fastest growing products in the frozen and ready-to-eat sector.
Zenhong, C.; Buwalda, P. L.
High security and robust optical image encryption approach based on computer-generated integral imaging pickup and iterative back-projection techniques
In this paper, a novel optical image encryption algorithm by combining the use of computer-generated integral imaging (CGII) pickup technique and iterative back-projection (IBP) technique is proposed. In this scheme, a color image to be encrypted which is firstly segregated into three channels: red, green, and blue. Each of these three channels is independently captured by using a virtual pinhole array and be computationally transformed as a sub-image array. Then, each of these three sub-image arrays are scrambled by the Fibonacci transformation (FT) algorithm, respectively. These three scrambled sub-image arrays are encrypted by the hybrid cellular automata (HCA), respectively. Ultimately, these three encrypted images are combined to produce the colored encrypted image. In the reconstruction process, because the computational integral imaging reconstruction (CIIR) is a pixel-overlapping reconstruction technique, the interference of the adjacent pixels will decrease the quality of the reconstructed image. To address this problem, we introduce an image super-resolution reconstruction technique, the image can be computationally reconstructed by the IBP technique. Some numerical simulations are made to test the validity and the capability of the proposed image encryption algorithm.
Li, Xiao Wei; Cho, Sung Jin; Kim, Seok Tae
Undersampled radial MR acquisition and highly constrained back projection (HYPR) reconstruction: potential medical imaging applications in the post-Nyquist era.
During the past several years there has been extensive study of alternative MR acquisition strategies such as spiral and radial. Vastly undersampled imaging with projections (VIPR) is a three-dimensional (3D) radial acquisition that provides acceptable images while violating the Nyquist theorem by factors of up to several hundred. For applications like magnetic resonance angiography (MRA), VIPR provides sparse data sets with incoherent artifacts that satisfy the requirements of emerging reconstruction approaches like iterative image norm minimization (compressed sensing) and highly constrained back projection (HYPR). All of these tools can be used in combination with parallel imaging to provide extremely high acceleration factors in MRI. In this review we do not attempt to do justice to the many exciting developments in the general field of constrained reconstruction but focus on preliminary results using VIPR and HYPR for non-Cartesian, Nyquist-violating MRI and the extension of HYPR processing to a broad range of medical imaging applications in which the acquisitions satisfy the Nyquist theorem but lack sufficient signal-to-noise ratio (SNR), leading to the possibility of radiation reduction, increased ultrasound resolution and field-of-view, and improved dynamic display of radiotracers. PMID:19243031
Mistretta, Charles A
A recursive solution for a fading memory filter derived from Kalman filter theory
A simple recursive solution for a class of fading memory tracking filters is presented. A fading memory filter provides estimates of filter states based on past measurements, similar to a traditional Kalman filter. Unlike a Kalman filter, an exponentially decaying weight is applied to older measurements, discounting their effect on present state estimates. It is shown that Kalman filters and fading memory filters are closely related solutions to a general least squares estimator problem. Closed form filter transfer functions are derived for a time invariant, steady state, fading memory filter. These can be applied in loop filter implementation of the Deep Space Network (DSN) Advanced Receiver carrier phase locked loop (PLL).
Statman, J. I.
On Wiener-type filters in SPECT
International Nuclear Information System (INIS)
For 2D data with Poisson noise we give explicit formulae for the optimal space-invariant Wiener-type filter with some a priori geometric restrictions on the window function. We show that, under some natural geometric condition, this restrictedly optimal Wiener-type filter admits a very efficient approximation by an approximately optimal filter with an unknown object power spectrum. Generalizations to the case of some more general noise model are also given. Proceeding from these results we (a) explain, in particular, an efficiency of some well-known '1D' approximately optimal space-invariant Wiener-type filtering scheme with an unknown object power spectrum in single-photon-emission-computed tomography (SPECT) and positron emission tomography (PET) imaging based on the classical filtered back-projection (FBP) algorithm or its iterative use and (b) also propose an efficient 2D approximately optimal space-invariant Wiener-type filter with an unknown object power spectrum for SPECT imaging based on the generalized FBP algorithm (implementing the explicit formula for the nonuniform attenuation correction) and/or the classical FBP algorithm (used iteratively). An efficient space-variant version of the latter 2D filter is also announced. Numerical examples illustrating the aforementioned results in the framework of simulated SPECT imaging are given
Myocardial perfusion magnetic resonance imaging using sliding-window conjugate-gradient highly constrained back-projection reconstruction for detection of coronary artery disease.
Myocardial perfusion magnetic resonance imaging (MRI) with sliding-window conjugate-gradient highly constrained back-projection reconstruction (SW-CG-HYPR) allows whole left ventricular coverage, improved temporal and spatial resolution and signal/noise ratio, and reduced cardiac motion-related image artifacts. The accuracy of this technique for detecting coronary artery disease (CAD) has not been determined in a large number of patients. We prospectively evaluated the diagnostic performance of myocardial perfusion MRI with SW-CG-HYPR in patients with suspected CAD. A total of 50 consecutive patients who were scheduled for coronary angiography with suspected CAD underwent myocardial perfusion MRI with SW-CG-HYPR at 3.0 T. The perfusion defects were interpreted qualitatively by 2 blinded observers and were correlated with x-ray angiographic stenoses ?50%. The prevalence of CAD was 56%. In the per-patient analysis, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of SW-CG-HYPR was 96% (95% confidence interval 82% to 100%), 82% (95% confidence interval 60% to 95%), 87% (95% confidence interval 70% to 96%), 95% (95% confidence interval 74% to100%), and 90% (95% confidence interval 82% to 98%), respectively. In the per-vessel analysis, the corresponding values were 98% (95% confidence interval 91% to 100%), 89% (95% confidence interval 80% to 94%), 86% (95% confidence interval 76% to 93%), 99% (95% confidence interval 93% to 100%), and 93% (95% confidence interval 89% to 97%), respectively. In conclusion, myocardial perfusion MRI using SW-CG-HYPR allows whole left ventricular coverage and high resolution and has high diagnostic accuracy in patients with suspected CAD. PMID:22264595
Ma, Heng; Yang, Jun; Liu, Jing; Ge, Lan; An, Jing; Tang, Qing; Li, Han; Zhang, Yu; Chen, David; Wang, Yong; Liu, Jiabin; Liang, Zhigang; Lin, Kai; Jin, Lixin; Bi, Xiaoming; Li, Kuncheng; Li, Debiao
The improvement of accuracy in using the smoothing filter instead of the Kalman filter is discussed. Factors of improvement for velocity errors of up to four are shown for position measurements. Smoothing equations are presented, and it is shown that smoothing equations for the smoothing filter appear to be stable.
Lear, W. H.
In this activity, students filter different substances through a plastic window screen, different sized hardware cloth and poultry netting. Their model shows how the thickness of a filter in the kidney is imperative in deciding what will be filtered out and what will stay within the blood stream.
Integrated Teaching And Learning Program
Extensions to polar formatting with spatially variant post-filtering
The polar format algorithm (PFA) is computationally faster than back projection for producing spotlight mode synthetic aperture radar (SAR). This is very important in applications such as video SAR for persistent surveillance, as images may need to be produced in real time. PFA's speed is largely due to making a planar wavefront assumption and forming the image onto a regular grid of pixels lying in a plane. Unfortunately, both assumptions cause loss of focus in airborne persistent surveillance applications. The planar wavefront assumption causes a loss of focus in the scene for pixels that are far from scene center. The planar grid of image pixels causes loss of the depth of focus for conic flight geometries. In this paper, we present a method to compensate for the loss of depth of focus while warping the image onto a terrain map to produce orthorectified imagery. This technique applies a spatially variant post-filter and resampling to correct the defocus while dewarping the image. This work builds on spatially variant post-filtering techniques previously developed at Sandia National Laboratories in that it incorporates corrections for terrain height and circular flight paths. This approach produces high quality SAR images many times faster than back projection.
Garber, Wendy L.; Hawley, Robert W.
Application of circular filter inserts
International Nuclear Information System (INIS)
High efficiency particulate air (HEPA) filters are used in the ventilation of nuclear plant as passive clean-up devices. Traditionally, the work-horse of the industry has been the rectangular HEPA filter. An assessment of the problems associated with remote handling, changing, and disposal of these rectangular filters suggested that significant advantages to filtration systems could be obtained by the adoption of HEPA filters with circular geometry for both new and existing ventilation plants. This paper covers the development of circular geometry filters and highlights the advantages of this design over their rectangular counterparts. The work has resulted in a range of commercially available filters for flows from 45 m3/h up to 3400 m3/h. This paper also covers the development of a range of sizes and types of housings that employ simple change techniques which take advantage of the circular geometry. The systems considered here have been designed in response to the requirements for shielded (remote filter change) and for unshielded facilities (potentially for bag changing of filters). Additionally the designs have allowed for the possibility of retrofitting circular geometry HEPA filters in place of the rectangular geometry filter
International Nuclear Information System (INIS)
A filter for removing liquid droplet, or solid particle, aerosols from a gas stream includes layers of a high voidage fibrous material with fibre diameters typically 4 microns, and drainage channels for liquid between successive fibrous layers. The filter may be formed entirely of stainless steel, or the layers may comprise glass fibres. A central spray nozzle allows a tubular, outward-flow filter to be washed clear in situ
Survey on Spam Filtering Techniques
Digital Repository Infrastructure Vision for European Research (DRIVER)
In the recent years spam became as a big problem of Internet and electronic communication. There developed a lot of techniques to fight them. In this paper the overview of existing e-mail spam filtering methods is given. The classification, evaluation, and comparison of traditional and learning-based methods are provided. Some personal anti-spam products are tested and compared. The statement for new approach in spam filtering technique is considered.
Saadat Nazirova
Survey on Spam Filtering Techniques
Directory of Open Access Journals (Sweden)
Full Text Available In the recent years spam became as a big problem of Internet and electronic communication. There developed a lot of techniques to fight them. In this paper the overview of existing e-mail spam filtering methods is given. The classification, evaluation, and comparison of traditional and learning-based methods are provided. Some personal anti-spam products are tested and compared. The statement for new approach in spam filtering technique is considered.
Saadat Nazirova
Students learn how CCD cameras use color filters to create astronomical images in this Moveable Museum unit. The four-page PDF guide includes suggested general background readings for educators, activity notes, and step-by-step directions. Students look at black-and-white photos to understand gray scale and construct simple red and green cellophane filters and observe magazine images through them.
???????????? Optimization of the Particle Filter Algorithm
Directory of Open Access Journals (Sweden)
Full Text Available ????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????In this paper, two problems were explicated by the detailed presentation of basic concepts and prin- ciples of the particle filter algorithm. One is particle impoverishment which dues to re-sampling, and another is particle degeneracy. To overcome these problems, existed methods of particle filter optimization are analy- zed. Finally, this paper presented a method that combine particle filter with intelligent algorithm, the combi- nation algorithm can overcome the shortcomings of particle filter effectively. Simulation results show that it is superior to the traditional particle filter optimization algorithm.
An area efficient low noise 100 Hz low-pass filter
Digital Repository Infrastructure Vision for European Research (DRIVER)
A technique based on scaling a filter's capacitor currents to improve the noise performance of low frequency continuous-time filters is presented. Two 100 Hz low-pass filters have been implemented: a traditional low pass filter (as reference), and a filter utilizing the above mentioned current scaling technique. The two filters utilize approximately the same silicon area. The scaled filter implements the scaling by use of a MOS based current conveyor type CCII. Measurements indicate that the ...
Gadamers verständnis der tradition
Directory of Open Access Journals (Sweden)
Full Text Available (nema?ki In diesem Aufsatz man Gadamers Verständnis der wichtigen hermeneutischen Begriffe des Vorurteils, der Autorität und der Tradition erörtet. Der Vollzug des Verstehens, in dem die Vorurteile unvermeidlich sind, wird als Prozeß ihre ununterbrechende Korrektion bestimmt. Die positive Auswertung des begrifflichen Paar Autorität-Tradition ist ein karakteristischen Motiv der philosophischen Hermeneutik, für die die Autorität kein negativen Mitklang hat, sondern auf freie und rationelle Annahmung begründet ist. Der Zusammenhang des Verstehens und der Tradition ist eine dynamische Beziehung, in die weder Tradition noch das Subjekt des Verstehens ungeändert bleiben. Daraus führt man zwei Implikationen aus: daß der Sinn eines Textes kann man nie ausschöpfen, und seines Verstehen ein unendlichen Prozeß ist; und daß die Suspension der Vorurteilen nur gelingt, wo die Tradition sie sozusagen 'filtriert'. Der Author stellt eine Spannung aus, zwischen Gadamers Verständnis der hermeneutischen Produktivität der Tradition und des zeitlichen Abstand als Instanz die dem Verstehen beiträgt.
Radoj?i? Saša
Emission computerized axial tomography from multiple gamma-camera views using frequency filtering
International Nuclear Information System (INIS)
Emission computerized axial tomography is achievable in any nuclear medicine department from multiple gamma camera views. Data are collected by rotating the patient in front of the camera. A simple fast algorithm is implemented, known as the convolution technique: first the projection data are Fourier transformed and then an original filter designed for optimizing resolution and noise suppression is applied; finally the inverse transform of the latter operation is back-projected. This program, which can also take into account the attenuation for single photon events, was executed with good results on phantoms and patients. We think that it can be easily implemented for specific diagnostic problems. (orig.)
Robust filtering for uncertain systems a parameter-dependent approach
This monograph provides the reader with a systematic treatment of robust filter design, a key issue in systems, control and signal processing, because of the fact that the inevitable presence of uncertainty in system and signal models often degrades the filtering performance and may even cause instability. The methods described are therefore not subject to the rigorous assumptions of traditional Kalman filtering. The monograph is concerned with robust filtering for various dynamical systems with parametric uncertainties, and focuses on parameter-dependent approaches to filter design. Classical filtering schemes, like H2 filtering and HĄ filtering, are addressed, and emerging issues such as robust filtering with constraints on communication channels and signal frequency characteristics are discussed. The text features: · design approaches to robust filters arranged according to varying complexity level, and emphasizing robust filtering in the parameter-dependent framework for the first time; ·...
Gao, Huijun
Intelligent Optimize Design of LCL Filter for Three-Phase Voltage-Source PWM Rectifier
Digital Repository Infrastructure Vision for European Research (DRIVER)
Compared to traditional L filter, a LCL filter is more effective on reducing harmonic distortion at switch frequency. So it is important to choose the LCL filter parameters to achieve good filtering effect. This paper introduces some traditional design methods. Design of a LCL filter by genetic algorithm (GA) and particle swam optimization (PSO) are presented in this paper and comparison of the two intelligent optimization. Simulation result and calculate data are provided to prove that intel...
Sun, Wei; Chen, Zhe; Wu, Xiaojie
Family Customs and Traditions.
Recognizing the importance of maintaining open communication with immediate and extended family members, this book provides a compilation of ideas for family traditions and customs that are grounded in compassion and human kindness. The traditions were gathered from families in the United States and Canada who responded to advertisements in…
MacGregor, Cynthia
Directory of Open Access Journals (Sweden)
Full Text Available In this paper I present the traditional fishing tools used in the area of the Danube Delta. More precisely, I speak about the village of Sfantu Gheorghe, a traditional fishing village, where the fishing activity has been the main activity along the years and where, lately, there have been major changes due to the decrease of the fish species.
STOICA Georgeta
Imaging the Rupture Front and Slip Distribution by the Back-projection of P-wave Amplitude from Strong-motion Records: A Case Study for the 2010 Jiasian, Taiwan, Earthquake
We propose a new approach of imaging earthquake source rupture process by direct back-projection of local P-wave displacement in strong-motion records. This approach is applied to estimate the slip distribution of an earthquake occurred in March 4, 2010, in Jiasian in southern Taiwan. Hypocenter of the Jiasian earthquake (Mw=6.0 and ML=6.4) is located at 22.96°N and 120.70°E with a focal depth of 23 km. Source imaging result shows that the rupture initiated from the hypocenter, and then a relatively small slip occurred in the northern part of the fault zone, and final propagated in the northwestern direction, in agreement with the distribution of aftershocks. Majority of the slip occurred in the western part of the epicenter, consistent with the dislocation model obtained from geodetic observations. This approach is computationally efficient and automatic. It allows for rapid determination of rupture front propagation and slip distribution after earthquakes using real-time strong-motion records, and provides important and useful information for seismic hazard mitigation.
Chao, W.; Zhao, L.; Wu, Y.
International Nuclear Information System (INIS)
General problems pertaining to production and usage of millipore or nuclear filters are presented. Production of nuclear filter pores is based on different rates of etching of an initial polymer and its parts which have been subjected to radiation destruction under the action of accelerated heavy ions. Basing on the results of experiments carried out on a heavy ion cyclotron, a conclusion has been drawn that the most suitable for irradiation of films are xenon ions (Xe9+) with an energy of 150 MeV having a value of dE/dx=80 MeV/mg/cm2, and also ions MeV/mg/cm2 of argon Ar6+. As an irradiated polymer material use was of lavsan (dacron). For water the filter capacity constituted 1 m3/m2xh at the pore diameter d=0.1 ?m, and 100m3/m2xh at d=1 ?m. For air the capacity proved to be 200-300 times higher. Wide possibilities of application of nuclear filters for, primarily, the processes of fine refinement, separation and concentration of various products, both liquid and gaseous, are shown
Digital Repository Infrastructure Vision for European Research (DRIVER)
In the Library with the Lead Pipe welcomes Audrey Barbakoff, a librarian at the Milwaukee Public Library, and Ahniwa Ferrari, Virtual Experience Manager at the Pierce County Library System in Washington, for a point-counterpoint piece on filtering in libraries. The opinions expressed here are those of the authors, and are not endorsed by their employers. [...
Directory of Open Access Journals (Sweden)
Full Text Available In the Library with the Lead Pipe welcomes Audrey Barbakoff, a librarian at the Milwaukee Public Library, and Ahniwa Ferrari, Virtual Experience Manager at the Pierce County Library System in Washington, for a point-counterpoint piece on filtering in libraries. The opinions expressed here are those of the authors, and are not endorsed by their employers. [...
Audrey Barbakoff
The 3-D alignment of objects in dynamic PET scans using filtered sinusoidal trajectories of sinogram
International Nuclear Information System (INIS)
In this study, our goal is to employ a novel 3-D alignment method for dynamic positron emission tomography (PET) scans. Because the acquired data (i.e. sinograms) often contain noise considerably, filtering of the data prior to the alignment presumably improves the final results. In this study, we utilized a novel 3-D stackgram domain approach. In the stackgram domain, the signals along the sinusoidal trajectory signals of the sinogram can be processed separately. In this work, we performed angular stackgram domain filtering by employing well known 1-D filters: the Gaussian low-pass filter and the median filter. In addition, we employed two wavelet de-noising techniques. After filtering we performed alignment of objects in the stackgram domain. The local alignment technique we used is based on similarity comparisons between locus vectors (i.e. the signals along the sinusoidal trajectories of the sinogram) in a 3-D neighborhood of sequences of the stackgrams. Aligned stackgrams can be transformed back to sinograms (Method 1), or alternatively directly to filtered back-projected images (Method 2). In order to evaluate the alignment process, simulated data with different kinds of additive noises were used. The results indicated that the filtering prior to the alignment can be important concerning the accuracy
Energy Technology Data Exchange (ETDEWEB)
Metal films perforated with subwavelength hole arrays have been show to demonstrate an effect known as Extraordinary Transmission (EOT). In EOT devices, optical transmission passbands arise that can have up to 90% transmission and a bandwidth that is only a few percent of the designed center wavelength. By placing a tunable dielectric in proximity to the EOT mesh, one can tune the center frequency of the passband. We have demonstrated over 1 micron of passive tuning in structures designed for an 11 micron center wavelength. If a suitable midwave (3-5 micron) tunable dielectric (perhaps BaTiO{sub 3}) were integrated with an EOT mesh designed for midwave operation, it is possible that a fast, voltage tunable, low temperature filter solution could be demonstrated with a several hundred nanometer passband. Such an element could, for example, replace certain components in a filter wheel solution.
Passmore, Brandon Scott; Shaner, Eric Arthur; Barrick, Todd A.
Digital Repository Infrastructure Vision for European Research (DRIVER)
It is not uncommon to find the collaborative process associated with innovation, whether by the participants themselves (Fitch 2007: 93) or the funding bodies supporting them (Haydn and Windsor 2007: 30-31). This paper investigates collaboration within a more traditional musical context and addresses two main questions in so doing: to what extent did composer and performer collaborate and can collaboration play a role within traditional compositional practice? By viewing the composer-performe...
Armstrong, T.; Capulet, E.
International Nuclear Information System (INIS)
The theory of filtered neutron beams is outlined. Details of filtered reactor beams including filter design criteria, possible improvements in filter at reactors and applications of filtered reactor beams are discussed. Characteristics and applications of filtered time-of-flight beams are described. (U.K.)
Energy Technology Data Exchange (ETDEWEB)
Filters were formed from ceramic fibers, organic fibers, and a ceramic bond phase using a papermaking technique. The distribution of particulate ceramic bond phase was determined using a model silicon carbide system. As the ceramic fiber increased in length and diameter the distance between particles decreased. The calculated number of particles per area showed good agreement with the observed value. After firing, the papers were characterized using a biaxial load test. The strength of papers was proportional to the amount of bond phase included in the paper. All samples exhibited strain-tolerant behavior.
Holmes, B.L.; Janney, M.A.
Quantitative gated SPECT: the effect of reconstruction filter on calculated left ventricular ejection fractions and volumes
International Nuclear Information System (INIS)
Gated SPECT (GSPECT) offers the possibility of obtaining additional functional information from perfusion studies, including calculation of left ventricular ejection fraction (LVEF). The calculation of LVEF relies upon the identification of the endocardial surface, which will be affected by the spatial resolution and statistical noise in the reconstructed images. The aim of this study was to compare LVEFs and ventricular volumes calculated from GSPECT using six reconstruction filters. GSPECT and radionuclide ventriculography (RNVG) were performed on 40 patients; filtered back projection was used to reconstruct the datasets with each filter. LVEFs and volumes were calculated using the Cedars-Sinai QGS package. The correlation coefficient between RNVG and GSPECT ranged from 0.81 to 0.86 with higher correlations for smoother filters. The narrowest prediction interval was 11±2%. There was a trend towards higher LVEF values with smoother filters, the ramp filter yielding LVEFs 2.55±3.10% (p<0.001) lower than the Hann filter. There was an overall fall in ventricular volumes with smoother filters with a mean difference of 13.98±10.15 ml (p<0.001) in EDV between the Butterworth-0.5 and Butterworth-0.3 filters. In conclusion, smoother reconstruction filters lead to lower volumes and higher ejection fractions with the QGS algorithm, with the Butterworth-0.4 filter giving the highest correlation with LVEFs from RNVG. Even if the optimal filter is chosen the uncertainty in the measured ejection fractions is still too great to be clinically acceptable. (author)
Centers for Disease Control (CDC) Podcasts
In this podcast, a Latina nutrition educator shows how a community worked with local farmers to grow produce traditionally enjoyed by Hispanic/Latinos. Created: 11/1/2007 by National Diabetes Education Program (NDEP), a joint program of the Centers for Disease Control and Prevention and the National Institutes of Health. Date Released: 11/10/2007.
This article presents a recipe for non-traditional wraps. In this article, the author describes how adults and children can help with the recipe and the skills involved with this recipe. The bigger role that children can play in the making of the item the more they are apt to try new things and appreciate the texture and taste.
Owens, Buffy
Presents pro and con comments with regards to 1975 APA presidential address under the heading of the value of traditions. Other comments are subsumed under the headings of biological versus social evolution, and the genetic basis of behavior especially of altruism. (Author/AM)
Brewer, Marilynn B.; And Others
Applicapability of Traditional Ceramic for Water Treatment in Small Communities
Digital Repository Infrastructure Vision for European Research (DRIVER)
There is a need for simple and inexpensive water supply systems in small communities, mainly because of high costs and water resource shortages. Ceramic filters used as a Point-of-Use (POU) system could serve as a safe and inexpensive means for supplying water. In this research we looked at the possibility of using Iranian traditional ceramics as filters for drinking water, bearing in mind the importance of ceramic filters as a POU system. A number of parameters relating to water quality were...
Mokhtari, M.; Naddafi, K.; Mahvi, A. H.; Naseri, S.
Challenging tradition in Nigeria.
In Nigeria since 1987, the National Association of Nigeria Nurses and Midwives (NSNNM) has used traditional medial and traditional health care workers to curtail the practice of female circumcision. Other harmful traditions are being changed also, such as early marriage, taboos of pregnancy and childbirth, and scarification. 30,000 member of NANNM are involved in this effort to halt the harmful practices themselves and to change community opinion. The program involved national and state level workshops on harmful health consequences of traditional practices and instruction on how to conduct focus group discussions to assess women's beliefs and practices. The focus groups were found to be a particularly successful method of opening up discussion of taboo topics and expressing deep emotions. The response to the knowledge that circumcision was not necessary was rage and anger, which was channeled into advocacy roles or change in the practice. The result was the channeled into advocacy roles for change in the practice. The result was the development of books, leaflets and videos. One community group designed a dress with a decorative motif of tatoos and bodily cuts to symbolize circumcision and scarring. Plays and songs were written and performed. Artists provided models of female genitalia both before and after circumcision. The campaign has been successful in bringing this issue to the public attention in prominent ways, such a national television, health talk shows, and women;s magazines. One of the most important results of the effort has been the demonstration that culture and tradition can be changed from within, rather than from outside imposition of values and beliefs. PMID:12284522
Supriya, K E
??????????? Optimized Cooperative Filtering Algorithm
Directory of Open Access Journals (Sweden)
Full Text Available ???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????Cooperative Filtering algorithm is one of the most successful technologies in the application of personalized recommendation system. However, the users' identities and interests are very complicated in the normal network, which results in the inaccuracy of the recommendation. However, the appearance of social network provides users with a relatively green and safe communication platform. This paper in terms of the problems in the personalized recommendation system of social network comes up with the trust-based nearest neighbor algorithm which optimizes the traditional NN algorithm and provides recommendation by analyzing trust between the social network users. The experimental results show that the modified algorithm greatly improves the recommendation accuracy and raises the users' degree of satisfaction.
The first site related to water filtration is from the US Environmental Agency entitled EPA Environmental Education: Water Filtration (1 ). The two-page document explains the need for water filtration and the steps water treatment plants take to purify water. To further understand the process, a demonstration project is provided that illustrates these purification steps, which include coagulation, sedimentation, filtration, and disinfection. The second site is an interesting Flash animation called Filtration: How Does it Work (2 ) provided by Canada's Prairie Farm Rehabilitation Administration. Visitors will learn various types of filtration procedures and systems and the materials that are used such as carbon and sand. Next, from the National Science Foundation is a learning activity called Get Out the Gunk (3 ). Using just a few simple items from around the house, kids will be able to answer questions like "Does a filter work better with a lot of water rushing through, or a small trickle?" and "Does it make the water cleaner if you pour it through a filter twice?" The fourth Web site, Rapid Sand Filtration (4 ), is provided by Dottie Schmitt and Christie Shinault of Virginia Tech. The authors describe the process, which involves the flow of water through a bed of granular media, normally following settling basins in conventional water treatment trains to remove any particulate matter left over after flocculation and settling. Along with its thorough description, readers can view illustrations and photographs that further explain the process. The Vegetative Buffer Strips for Improved Surface Water Quality (5) Web site is provided by the Iowa State University Extension office. The document explains what vegetative buffer strips are, how they filter contaminants and sediment from surface water, how effective they are, and more. The sixth offering is a file called Infiltration Basins and Trenches (6) that is offered by the University of Wisconsin Extension. These structures are intended to collect water, have it infiltrate into the ground, and have it purified along the way. This document explains how effective they are at removing pollutants, how to install them, design guidelines, maintenance, and more. Next, from a site called Wilderness Survial.net is the Water Filtration Devices (7) page. Visitors read how to make a filtering system out of cloth, sand, crushed rock, charcoal, or a hollow log, although as is stated, the water still has to be purified. The last site, from the US Geological Survey, is called A Visit to a Wastewater-Treatment Plant: Primary Treatment of Wastewater (8). Although geared towards children, the site does a good job of explaining what happens at each stage of the treatment process and how pollutants are removed to help keep water clean. Everything from screening, pumping, aerating, sludge and scum removal, killing bacteria, and what is done with wastewater residuals is covered.
Brieske, Joel A.
Filters in 2D and 3D Cardiac SPECT Image Processing.
Nuclear cardiac imaging is a noninvasive, sensitive method providing information on cardiac structure and physiology. Single photon emission tomography (SPECT) evaluates myocardial perfusion, viability, and function and is widely used in clinical routine. The quality of the tomographic image is a key for accurate diagnosis. Image filtering, a mathematical processing, compensates for loss of detail in an image while reducing image noise, and it can improve the image resolution and limit the degradation of the image. SPECT images are then reconstructed, either by filter back projection (FBP) analytical technique or iteratively, by algebraic methods. The aim of this study is to review filters in cardiac 2D, 3D, and 4D SPECT applications and how these affect the image quality mirroring the diagnostic accuracy of SPECT images. Several filters, including the Hanning, Butterworth, and Parzen filters, were evaluated in combination with the two reconstruction methods as well as with a specified MatLab program. Results showed that for both 3D and 4D cardiac SPECT the Butterworth filter, for different critical frequencies and orders, produced the best results. Between the two reconstruction methods, the iterative one might be more appropriate for cardiac SPECT, since it improves lesion detectability due to the significant improvement of image contrast. PMID:24804144
Lyra, Maria; Ploussi, Agapi; Rouchota, Maritina; Synefia, Stella
Filters in 2D and 3D Cardiac SPECT Image Processing
Nuclear cardiac imaging is a noninvasive, sensitive method providing information on cardiac structure and physiology. Single photon emission tomography (SPECT) evaluates myocardial perfusion, viability, and function and is widely used in clinical routine. The quality of the tomographic image is a key for accurate diagnosis. Image filtering, a mathematical processing, compensates for loss of detail in an image while reducing image noise, and it can improve the image resolution and limit the degradation of the image. SPECT images are then reconstructed, either by filter back projection (FBP) analytical technique or iteratively, by algebraic methods. The aim of this study is to review filters in cardiac 2D, 3D, and 4D SPECT applications and how these affect the image quality mirroring the diagnostic accuracy of SPECT images. Several filters, including the Hanning, Butterworth, and Parzen filters, were evaluated in combination with the two reconstruction methods as well as with a specified MatLab program. Results showed that for both 3D and 4D cardiac SPECT the Butterworth filter, for different critical frequencies and orders, produced the best results. Between the two reconstruction methods, the iterative one might be more appropriate for cardiac SPECT, since it improves lesion detectability due to the significant improvement of image contrast.
Ploussi, Agapi; Synefia, Stella
Novel Backup Filter Device for Candle Filters.
The currently preferred means of particulate removal from process or combustion gas generated by advanced coal-based power production processes is filtration with candle filters. However, candle filters have not shown the requisite reliability to be comme...
B. Bishop R. Goldsmith G. Dunham A. Henderson
Energy Technology Data Exchange (ETDEWEB)
A well filter is proposed, which contains a shell and deflectors, which form filtering slots. To ensure the capability of wash through of the filter without lifting it to the surface, the deflectors are hinged to the shell.
Leontyev, S.G.; Leontyeva, L.S.
A New Glass of Nonlinear Filters: Microstatistic Volterra Filters
Digital Repository Infrastructure Vision for European Research (DRIVER)
In this paper a new subset of the time-invariant microstatistic filters so-called microstatistic Volterra filters are proposed. This class of nonlinear filters is based on the idea of the conventional microstatistic filter generalization by substituting Wiener filters applied in the conventional microstatistic filter structure by Volterra filters. The advantage of the microstatistic Volterra filters in comparison with the Wiener filters, Volterra filters and conventional microstatistic filter...
Kocur, D.; Drutarovsky, M.; Marchevsky, S.
Direct analysis of air filter samples for alpha emitting isotopes.
The traditional method for determination of alpha emitting isotopes on air filters has been to process the samples by radiochemical methods. However, this method is too slow for cases of incidents involving radioactive materials where the determination of...
A. H. Mohagheghi F. Ghanbari S. B. Ebara M. E. Enghauser S. N. Bakhtiar
Quantitative comparison between full-spectrum and filter-based imaging in hyperspectral fluorescence microscopy
Digital Repository Infrastructure Vision for European Research (DRIVER)
We implement a filterless illumination scheme on a hyperspectral fluorescence microscope to achieve full-range spectral imaging. The microscope employs polarisation filtering, spatial filtering and spectral unmixing filtering to replace the role of traditional filters. Quantitative comparisons between full-spectrum and filter-based microscopy are provided in the context of signal dynamic range and accuracy of measured fluorophores' emission spectra. To show potential applications, a five-co...
Gao, L.; Hagen, N.; Tkaczyk, T. S.
Non-Traditional Vectors for Paralytic Shellfish Poisoning
Directory of Open Access Journals (Sweden)
Full Text Available Paralytic shellfish poisoning (PSP, due to saxitoxin and related compounds, typically results from the consumption of filter-feeding molluscan shellfish that concentrate toxins from marine dinoflagellates. In addition to these microalgal sources, saxitoxin and related compounds, referred to in this review as STXs, are also produced in freshwater cyanobacteria and have been associated with calcareous red macroalgae. STXs are transferred and bioaccumulate throughout aquatic food webs, and can be vectored to terrestrial biota, including humans. Fisheries closures and human intoxications due to STXs have been documented in several non-traditional (i.e. non-filter-feeding vectors. These include, but are not limited to, marine gastropods, both carnivorous and grazing, crustacea, and fish that acquire STXs through toxin transfer. Often due to spatial, temporal, or a species disconnection from the primary source of STXs (bloom forming dinoflagellates, monitoring and management of such non-traditional PSP vectors has been challenging. A brief literature review is provided for filter feeding (traditional and nonfilter feeding (non-traditional vectors of STXs with specific reference to human effects. We include several case studies pertaining to management actions to prevent PSP, as well as food poisoning incidents from STX(s accumulation in non-traditional PSP vectors.
Sara Watt Longan
Generic Hardware Architectures for Sampling and Resampling in Particle Filters
Digital Repository Infrastructure Vision for European Research (DRIVER)
Particle filtering is a statistical signal processing methodology that has recently gained popularity in solving several problems in signal processing and communications. Particle filters (PFs) have been shown to outperform traditional filters in important practical scenarios. However their computational complexity and lack of dedicated hardware for real-time processing have adversely affected their use in real-time applications. In this paper, we present generic architectures for the implem...
Akshay Athalye; Miodrag Boli?; Sangjin Hong; Djuri, Petar M.
Research of Collaborative Filtering Recommendation Algorithm based on Network Structure
Digital Repository Infrastructure Vision for European Research (DRIVER)
This paper combines the classic collaborative filtering algorithm with personalized recommendation algorithm based on network structure. For the data sparsity and malicious behavior problems of traditional collaborative filtering algorithm, the paper introduces a new kind of social network-based collaborative filtering algorithm. In order to improve the accuracy of the personalized recommendation technology, we first define empty state in the state space of multi-dimensional semi-Markov proce...
Peng, Hui
Synthesis of polynomial filters
Agafonov's (1970) method for the synthesis of polynomial microwave filters is extended to filters whose circuits cannot be divided into individual parts. Filter design relationships are obtained for three classes of circuits. The proposed method can be applied to circuits with lumped and distributed constants. It is particularly effective for the synthesis of complex filters, e.g., those based on coupled microstrip lines.
Agafonov, V. M.
Bayesian filtering in electronic surveillance
Fusion of passive electronic support measures (ESM) with active radar data enables tracking and identification of platforms in air, ground, and maritime domains. An effective multi-sensor fusion architecture adopts hierarchical real-time multi-stage processing. This paper focuses on the recursive filtering challenges. The first challenge is to achieve effective platform identification based on noisy emitter type measurements; we show that while optimal processing is computationally infeasible, a good suboptimal solution is available via a sequential measurement processing approach. The second challenge is to process waveform feature measurements that enable disambiguation in multi-target scenarios where targets may be using the same emitters. We show that an approach that explicitly considers the Markov jump process outperforms the traditional Kalman filtering solution.
Coraluppi, Stefano; Carthel, Craig
Enhanced 3D PET OSEM reconstruction using inter-update Metz filtering
International Nuclear Information System (INIS)
We present an enhancement of the OSEM (ordered set expectation maximization) algorithm for 3D PET reconstruction, which we call the inter-update Metz filtered OSEM (IMF-OSEM). The IMF-OSEM algorithm incorporates filtering action into the image updating process in order to improve the quality of the reconstruction. With this technique, the multiplicative correction image - ordinarily used to update image estimates in plain OSEM - is applied to a Metz-filtered version of the image estimate at certain intervals. In addition, we present a software implementation that employs several high-speed features to accelerate reconstruction. These features include, firstly, forward and back projection functions which make full use of symmetry as well as a fast incremental computation technique. Secondly, the software has the capability of running in parallel mode on several processors. The parallelization approach employed yields a significant speed-up, which is nearly independent of the amount of data. Together, these features lead to reasonable reconstruction times even when using large image arrays and non-axially compressed projection data. The performance of IMF-OSEM was tested on phantom data acquired on the GE Advance scanner. Our results demonstrate that an appropriate choice of Metz filter parameters can improve the contrast-noise balance of certain regions of interest relative to both plain and post-filtered OSEM, and to the GE commercial reprojection algorithm software. (author)
Unsolicited bulk email (aka. spam) is a major problem on the Internet. To counter spam, several techniques, ranging from spam filters to mail protocol extensions like hashcash, have been proposed. In this paper we investigate the effectiveness of several spam filtering techniques and technologies. Our analysis was performed by simulating email traffic under different conditions. We show that genetic algorithm based spam filters perform best at server level and naive Bayesian filters are the most appropriate for filtering at user level.
Garcia, F D; Basiuk, Vincent; Becoulet, Alain; Coulon, Jean-Pierre; Garcia, Flavio D.; Hoepman, Jaap-Henk; Hutter, Thierry; Saoutic, Vincent
Percutaneous retrieval of a vena cava filter from the right atrium: case report
International Nuclear Information System (INIS)
Migration of vena cava filters can occur spontaneously, but it can also occur as a result of entanglement of the filter with a guidewire, particularly during 'blind' (unguided) insertion of a central venous line. When a filter migrates to the heart, traditional practice has been either to leave the filter in place or to remove it surgically by means of open heart surgery and cardiopulmonary bypass. We found only 6 reports of successful percutaneous retrieval or repositioning of a vena cava filter (Table 1). We describe a new interventional technique for retrieving a filter from the right atrium and a novel endosurgical method for removing a filter from the innominate vein. (author)
Median filtering in multispectral filter array demosaicking
Digital Repository Infrastructure Vision for European Research (DRIVER)
Inspired by the concept of the colour filter array (CFA), the research community has shown much interest in adapting the idea of CFA to the multispectral domain, producing multispectral filter array (MSFAs). In addition to newly devised methods of MSFA demosaicking, there exists a wide spectrum of methods developed for CFA. Among others, some vector based operations can be adapted naturally for multispectral purposes. In this paper, we focused on studying two vector based median filtering met...
Wang, Xingbo; Thomas, Jean-baptiste; Hardeberg, Jon Yngve; Gouton, Pierre
Directory of Open Access Journals (Sweden)
Full Text Available The digital filter implementation in FPGA,utilising the dedicated hardware resources can effectively achieve ASIC-like performance while reducing development time cost and risks. Advantage of FPGA approach to digital filter implementation including sampling rates than are availablefrom traditional DSP chips. In this paper a low pass,band pass and highpass FIR filter is implemented on FPGA.This approach gives a better performance than the common filter structures in terms of speed of operation,cost and power consumption in real time.In this technique, codes for direct fixed point FIR filter have been realized. Modules such as multiplier, adder, ram and two's complement were used. For an N order filter the filter the number of registers and adders required is N and the number of multipliers required is N+1.For high speed and high throughput applications,MAC is used and that consumes less power.
Miniature wideband filter based on coupled-line sections and quasi-lumped element resonator
DEFF Research Database (Denmark)
A new design of a wideband bandpass filter is proposed, based on coupled-line sections and quasi-lumped element resonator, taking advantage of the last one to introduce two transmission zeros and suppress a spurious response. The proposed filter demonstrates significantly improved characteristics in comparison with traditional coupled-line filter and exhibits a very compact structure.
Zhurbenko, Vitaliy; Krozer, Viktor
Application of Moving Object Tracking Based on Kalman Filter Algorithm
Directory of Open Access Journals (Sweden)
Full Text Available The moving object module matching method base on Kalman Filter (KF algorithm which proposed to solve the problem of traditional moving object matching method's, that fault of huge searching range and weakness in real-time processing. Relative to traditional module matching method, the method mentioned here effectively improved the speed and the accuracy of object tracking. This method has tripled the object matching speed of traditional tracking method.
Xiao Zhansheng
The Hausa Lexicographic Tradition
Directory of Open Access Journals (Sweden)
Full Text Available
Abstract: Hausa, a major language of West Africa, is one of the most widely studied languagesof Sub-Saharan Africa. It has a rich lexicographic tradition dating back some two centuries. Sincethe first major vocabulary published in 1843 up to the present time, almost 60 lexicographic works— dictionaries, vocabularies, glossaries — have been published, in a range of metalanguages, fromEnglish to Hausa itself. This article traces the historical development of the major studies accordingto their type and function as general reference works, specialized works, pedagogical works, andterminological works. For each work, there is a general discussion of its size, accuracy of the phonological,lexical, and grammatical information, and the adequacy of its definitions and illustrativematerial. A complete list of the lexicographic works is included.
Keywords: ARABIC, BILINGUAL LEXICOGRAPHY, DIALECTAL VARIANTS, DICTIONARIES,ENGLISH, ETYMOLOGIES, FRENCH, GERMAN, GLOSSARIES, GRAMMATICALCATEGORIES, HAUSA, LANGUAGE LEARNING, LOANWORDS, NEOLOGISMS, NIGER,NIGERIA, ORTHOGRAPHY, PHONETIC TRANSCRIPTION, PHONOLOGY, RUSSIAN, STANDARDDIALECT, STANDARDIZATION, TERMINOLOGY, VOCABULARIES, WEST AFRICA.
Opsomming: Die leksikografiese tradisie in Hausa. Hausa, 'n belangrike taal vanWes-Afrika, is een van die tale van Afrika suid van die Sahara wat die wydste bestudeer word. Dithet 'n ryk leksikografiese tradisie wat ongeveer twee eeue oud is. Van die eerste groot woordeboekwat in 1843 gepubliseer is tot die hede is ongeveer 60 leksikografiese werke — woordeboeke,naamlyste, woordelyste — gepubliseer in 'n reeks metatale van Engels tot Hausa self. Hierdie artikelgaan die historiese ontwikkeling van die groter studies aan die hand van hulle tipe en funksieas algemene naslaanwerke, gespesialiseerde werke, opvoedkundige werke, en terminologiesewerke na. Vir elke werk is daar 'n algemene bespreking oor sy grootte, akkuraatheid van die fonologiese,leksikale en grammatikale inligting, en die toereikendheid van sy definisies en illustratiewemateriaal. 'n Volledige lys van die leksikografiese werke is ingesluit.
Sleutelwoorde: AANLEER VAN TAAL, ARABIES, DIALEKTIESE VARIANTE, DUITS,ENGELS, ETIMOLOGIEË, FONETIESE TRANSKRIPSIE, FONOLOGIE, FRANS, GRAMMATIESEKATEGORIEË, HAUSA, LEENWOORDE, NAAMLYSTE, NEOLOGISMES, NIGER,NIGERIË, ORTOGRAFIE, RUSSIES, STANDAARDDIALEK, STANDAARDISERING,
Roxana Ma Newman
Cordierite silicon nitride filters
Energy Technology Data Exchange (ETDEWEB)
The objective of this project was to develop a silicon nitride based crossflow filter. This report summarizes the findings and results of the project. The project was phased with Phase I consisting of filter material development and crossflow filter design. Phase II involved filter manufacturing, filter testing under simulated conditions and reporting the results. In Phase I, Cordierite Silicon Nitride (CSN) was developed and tested for permeability and strength. Target values for each of these parameters were established early in the program. The values were met by the material development effort in Phase I. The crossflow filter design effort proceeded by developing a macroscopic design based on required surface area and estimated stresses. Then the thermal and pressure stresses were estimated using finite element analysis. In Phase II of this program, the filter manufacturing technique was developed, and the manufactured filters were tested. The technique developed involved press-bonding extruded tiles to form a filter, producing a monolithic filter after sintering. Filters manufactured using this technique were tested at Acurex and at the Westinghouse Science and Technology Center. The filters did not delaminate during testing and operated and high collection efficiency and good cleanability. Further development in areas of sintering and filter design is recommended.
Sawyer, J.; Buchan, B. (Acurex Environmental Corp., Mountain View, CA (United States)); Duiven, R.; Berger, M. (Aerotherm Corp., Mountain View, CA (United States)); Cleveland, J.; Ferri, J. (GTE Products Corp., Towanda, PA (United States))
Survey of Sparse Adaptive Filters for Acoustic Echo Cancellation
Directory of Open Access Journals (Sweden)
Full Text Available This paper reviews the existing developments of adaptive methods of sparse adaptive filters for the identification of sparse impulse response in both network and acoustic echo cancellation from the last decade. A variety of different architectures and novel training algorithms have been proposed in literature. At present most of the work in echo cancellation on using more than one method. Sparse adaptive filters take the advantage of each method and showing good improvement in the sparseness measure performance. This survey gives an overview of existing sparse adaptive filters mechanisms and discusses their advantages over the traditional adaptive filters developed for echo cancellation.
Krishna Samalla
Presents responses to 10 common arguments against the use of Internet filters in libraries. Highlights include keyword blocking; selection of materials; liability of libraries using filters; users' judgments; Constitutional issues, including First Amendment rights; and censorship. (LRW)
Burt, David
Property Rights And Traditional Knowledge
Digital Repository Infrastructure Vision for European Research (DRIVER)
For the past several decades, there has been a push to provide some sort of right akin to an intellectual property right in traditional knowledge and traditional cultural expression. This push has encountered staunch resistance from a number of different quarters. Many of the objections are practical. However, underlying these practical concerns is a core philosophical concern. A system of traditional knowledge rights, this argument suggests, simply does not satisfy the basic rationale for gr...
Property rights and traditional knowledge
Digital Repository Infrastructure Vision for European Research (DRIVER)
For the past several decades, there has been a push to provide some sort of right akin to an intellectual property right in traditional knowledge and traditional cultural expression. This push has encountered staunch resistance from a number of different quarters. Many of the objections are practical. However, underlying these practical concerns is a core philosophical concern. A system of traditional knowledge rights, this argument suggests, simply does not satisfy the basic rationale for gr...
Reception of the Istrian musical tradition(s)
Digital Repository Infrastructure Vision for European Research (DRIVER)
The successive colonization of Istria with culturally differentiated populations, and peripheral position of the peninsula regarding both the Latin and Slav worlds, has conditioned interesting phenomena which defines the traditional life of the province. On the spiritual level it is primarily reflected in two cultural dimensions: the language and traditional music.
Maruši? Dario
Digital Repository Infrastructure Vision for European Research (DRIVER)
The ribosome filter hypothesis postulates that ribosomes are not simply translation machines but also function as regulatory elements that differentially affect or filter the translation of particular mRNAs. On the basis of new information, we take the opportunity here to review the ribosome filter hypothesis, suggest specific mechanisms of action, and discuss recent examples from the literature that support it.
Mauro, Vincent P.; Edelman, Gerald M.
Nonlinear Attitude Filtering Methods
This paper provides a survey of modern nonlinear filtering methods for attitude estimation. Early applications relied mostly on the extended Kalman filter for attitude estimation. Since these applications, several new approaches have been developed that have proven to be superior to the extended Kalman filter. Several of these approaches maintain the basic structure of the extended Kalman filter, but employ various modifications in order to provide better convergence or improve other performance characteristics. Examples of such approaches include: filter QUEST, extended QUEST, the super-iterated extended Kalman filter, the interlaced extended Kalman filter, and the second-order Kalman filter. Filters that propagate and update a discrete set of sigma points rather than using linearized equations for the mean and covariance are also reviewed. A two-step approach is discussed with a first-step state that linearizes the measurement model and an iterative second step to recover the desired attitude states. These approaches are all based on the Gaussian assumption that the probability density function is adequately specified by its mean and covariance. Other approaches that do not require this assumption are reviewed, including particle filters and a Bayesian filter based on a non-Gaussian, finite-parameter probability density function on SO(3). Finally, the predictive filter, nonlinear observers and adaptive approaches are shown. The strengths and weaknesses of the various approaches are discussed.
Markley, F. Landis; Crassidis, John L.; Cheng, Yang
Evaluation of median filtering after reconstruction with maximum likelihood expectation maximization (ML-EM) by real space and frequency space
International Nuclear Information System (INIS)
Maximum likelihood expectation maximization (ML-EM) image quality is sensitive to the number of iterations, because a large number of iterations leads to images with checkerboard noise. The use of median filtering in the reconstruction process allows both noise reduction and edge preservation. We examined the value of median filtering after reconstruction with ML-EM by comparing filtered back projection (FBP) with a ramp filter or ML-EM without filtering. SPECT images were obtained with a dual-head gamma camera. The acquisition time was changed from 10 to 200 (seconds/frame) to examine the effect of the count statistics on the quality of the reconstructed images. First, images were reconstructed with ML-EM by changing the number of iterations from 1 to 150 in each study. Additionally, median filtering was applied following reconstruction with ML-EM. The quality of the reconstructed images was evaluated in terms of normalized mean square error (NMSE) values and two-dimensional power spectrum analysis. Median filtering after reconstruction by the ML-EM method provided stable NMSE values even when the number of iterations was increased. The signal element of the image was close to the reference image for any repetition number of iterations. Median filtering after reconstruction with ML-EM was useful in reducing noise, with a similar resolution achieved by reconstruction with FBP and a ramp filter. Especially in images with poor count statistics, median filtering after reconstruction with ML-EM is effective as a simple, widely available method. (author)
Positive pressure filter respirator
Energy Technology Data Exchange (ETDEWEB)
A positive pressure filter respirator comprises a conventional full mask having an air inlet opening to which a filter cannister containing a filter is screw mounted. A fan is mounted immediately within the air opening inlet and within the contours of the full face mask so as to draw air through the filter and into the interior of the full face mask. A curved wall portion within the full face mask and formed integrally with the body of the face mask directs the air drawn through the filter across the visor of the full face mask.
Simpson, K.
Creating Filtered, Translated Newsfeeds
Directory of Open Access Journals (Sweden)
Full Text Available Google Translate's API creates the possibility to leverage machine translation to both filter global newsfeeds for content regarding a specific topic, and to aggregate filtered feed items as a newsfeed. Filtered items can be translated so that the resulting newsfeed can provide basic information about topic-specific news articles from around the globe in the desired language of the consumer. This article explores a possible solution for inputting alternate words and phrases in the user's native language, aggregating and filtering newsfeeds progammatically, managing filter terms, and using Google Translate's API.
Linn Marks Collins
A Traditional Library Goes Virtual.
Describes the change from a traditional, paper-based collection to an electronic library at Bell Canada's Information Resource Center in Montreal. Highlights include universal desktop access for users; library Web site; decline in traditional services to increased use of online services; materials, including books, consultant reports, and…
Boyd, Stephanie
International Nuclear Information System (INIS)
A filter changing unit has a door which interlocks with the door of a filter chamber so as to prevent contamination of the outer surfaces of the doors by radioactive material collected on the filter element and a movable support which enables a filter chamber thereonto to be stored within the unit in such a way that the doors of the unit and the filter chamber can be replaced. The door pivots and interlocks with another door by means of a bolt, a seal around the periphery lip of the first door engages the periphery of the second door to seal the gap. A support pivots into a lower filter element storage position. Inspection windows and glove ports are provided. The unit is releasably connected to the filter chamber by bolts engaging in a flange provided around an opening. (author)
Bias Reduction and Filter Convergence for Long Range Stereo
We are concerned here with improving long range stereo by filtering image sequences. Traditionally, measurement errors from stereo camera systems have been approximated as 3-D Gaussians, where the mean is derived by triangulation and the covariance by linearized error propagation. However, there are two problems that arise when filtering such 3-D measurements. First, stereo triangulation suffers from a range dependent statistical bias; when filtering this leads to over-estimating the true range. Second, filtering 3-D measurements derived via linearized error propagation leads to apparent filter divergence; the estimator is biased to under-estimate range. To address the first issue, we examine the statistical behavior of stereo triangulation and show how to remove the bias by series expansion. The solution to the second problem is to filter with image coordinates as measurements instead of triangulated 3-D coordinates.
Sibley, Gabe; Matthies, Larry; Sukhatme, Gaurav
Symmetric Phase Only Filtering for Improved DPIV Data Processing
The standard approach in Digital Particle Image Velocimetry (DPIV) data processing is to use Fast Fourier Transforms to obtain the cross-correlation of two single exposure subregions, where the location of the cross-correlation peak is representative of the most probable particle displacement across the subregion. This standard DPIV processing technique is analogous to Matched Spatial Filtering, a technique commonly used in optical correlators to perform the crosscorrelation operation. Phase only filtering is a well known variation of Matched Spatial Filtering, which when used to process DPIV image data yields correlation peaks which are narrower and up to an order of magnitude larger than those obtained using traditional DPIV processing. In addition to possessing desirable correlation plane features, phase only filters also provide superior performance in the presence of DC noise in the correlation subregion. When DPIV image subregions contaminated with surface flare light or high background noise levels are processed using phase only filters, the correlation peak pertaining only to the particle displacement is readily detected above any signal stemming from the DC objects. Tedious image masking or background image subtraction are not required. Both theoretical and experimental analyses of the signal-to-noise ratio performance of the filter functions are presented. In addition, a new Symmetric Phase Only Filtering (SPOF) technique, which is a variation on the traditional phase only filtering technique, is described and demonstrated. The SPOF technique exceeds the performance of the traditionally accepted phase only filtering techniques and is easily implemented in standard DPIV FFT based correlation processing with no significant computational performance penalty. An "Automatic" SPOF algorithm is presented which determines when the SPOF is able to provide better signal to noise results than traditional PIV processing. The SPOF based optical correlation processing approach is presented as a new paradigm for more robust cross-correlation processing of low signal-to-noise ratio DPIV image data."
Wernet, Mark P.
Kalman filtering technique for reactivity measurement
International Nuclear Information System (INIS)
Measurement of reactivity and its on-line display is of great help in calibration of reactivity control and safety devices and in the planning of suitable actions during the reactor operation. In traditional approaches the reactivity is estimated from reactor period or by solving the inverse point kinetic equation. In this paper, an entirely new approach based on the Kalman filtering technique has been presented. The theory and design of the reactivity measuring instrument based on the approach has been explained. Its performance has been compared with traditional approaches by estimation of transient reactivity from flux variation data recorded in a research reactor. It is demonstrated that the Kalman filtering approach is superior to other methods from the viewpoints of accuracy, noise suppression, and robustness against uncertainties in the reactor parameters. (author). 1 fig
Aurorae in Australian Aboriginal Traditions
Transient celestial phenomena feature prominently in the astronomical knowledge and traditions of Aboriginal Australians. In this paper, I collect accounts of the Aurora Australis from the literature regarding Aboriginal culture. Using previous studies of meteors, eclipses, and comets in Aboriginal traditions, I anticipate that the physical properties of aurora, such as their generally red colour as seen from southern Australia, will be associated with fire, death, blood, and evil spirits. The survey reveals this to be the case and also explores historical auroral events in Aboriginal cultures, aurorae in rock art, and briefly compares Aboriginal auroral traditions with other global indigenous groups, including the Maori of New Zealand.
Hamacher, Duane W
Aurorae in Australian Aboriginal Traditions
Transient celestial phenomena feature prominently in the astronomical knowledge and traditions of Aboriginal Australians. In this paper, I collect accounts of the Aurora Australis from the literature regarding Aboriginal culture. Using previous studies of meteors, eclipses, and comets in Aboriginal traditions, I anticipate that the physical properties of aurora, such as their generally red colour as seen from southern Australia, will be associated with fire, death, blood, and evil spirits. The survey reveals this to be the case and also explores historical auroral events in Aboriginal cultures, aurorae in rock art, and briefly compares Aboriginal auroral traditions with other global indigenous groups, including the Maori of New Zealand.
Hamacher, Duane W.
Complex Hilbert Transform Filter
Directory of Open Access Journals (Sweden)
Full Text Available Hilbert transform is a basic tool in constructing analytical signals for a various applications such as amplitude modulation, envelope and instantaneous frequency analysis, quadrature decoding, shift-invariant multi-rate signal processing and Hilbert-Huang decomposition. This work introduces a complex Hilbert transform (CHT filter, where the real and imaginary parts are a Hilbert transform pair. The CHT filtered signal is analytic, i.e. its Fourier transform is zero in negative frequency range. The CHT filter is constructed by half-sample delay operators based on the B-spline transform interpolation and decimation procedure. The CHT filter has an ideal phase response and the magnitude response is maximally flat in the frequency range 0 ? ? ? ?. The CHT filter has integer coefficients and the implementation in VLSI requires only summations and register shifts. We demonstrate the feasibility of the CHT filter in reconstruction of the sign modulated CMOS logic pulses in a fibre optic link.
Hannu Olkkonen
In contact with traditional medicine.
Nigerian traditional medical practice was a part of the empirical world traditional medicine. However, it is still with us after over 500 years of contacts with modern medical practice. It is the only form of medical are available to the majority of the Nigerian population and is also the first line of defence against disease in a great proportion of people even amongst the enlightened city dwellers and the elites. Although the Nigerian traditional healers including the herbalists are general practitioners, the more successful ones do specialise. Some of the traditional herbal treatments for common diseases as well as preventive medical practice are examined. Recommendations for future improvements in the systems are made. PMID:555133
Osuhor, P C; Osuhor, A
Sensory Pollution from Bag Filters, Carbon Filters and Combinations
DEFF Research Database (Denmark)
Used ventilation filters are a major source of sensory pollutants in air handling systems. The objective of the present study was to evaluate the net effect that different combinations of filters had on perceived air quality after 5 months of continuous filtration of outdoor suburban air. A panel of 32 subjects assessed different sets of used filters and identical sets consisting of new filters. Additionally, filter weights and pressure drops were measured at the beginning and end of the operation period. The filter sets included single EU5 and EU7 fiberglass filters, an EU7 filter protected by an upstream pre-filter (changed monthly), an EU7 filter protected by an upstream activated carbon (AC) filter, and EU7 filters with an AC filter either downstream or both upstream and downstream. In addition, two types of stand-alone combination filters were evaluated: a bag-type fiberglass filter that contained AC and a synthetic fiber cartridge filter that contained AC. Air that had passed through used filters was most acceptable for those sets in which an AC filter was used downstream of the particle filter. Comparable air quality was achieved with the stand-alone bag filter that contained AC. Furthermore, its pressure drop changed very little during the 5 months of service, and it had the added benefit of removing a large fraction of ozone from the airstream. If similar results are obtained over a wider variety of soiling conditions, such filters may be a viable solution to a long recognized problem.
Bekö, Gabriel; Clausen, Geo
Health traditions of Sikkim Himalaya
Digital Repository Infrastructure Vision for European Research (DRIVER)
Ancient medical systems are still prevalent in Sikkim, popularly nurtured by Buddhist groups using the traditional Tibetan pharmacopoeia overlapping with Ayurvedic medicine. Traditional medical practices and their associated cultural values are based round Sikkim's three major communities, Lepcha, Bhutia and Nepalis. In this study, a semi-structured questionnaire was prepared for folk healers covering age and sex, educational qualification, source of knowledge, types of practices, experienc...
Panda, Ashok Kumar; Misra, Sangram
Configurable Multirate Filter Banks
Digital Repository Infrastructure Vision for European Research (DRIVER)
Multimedia communications require efficient and real-time implementations of multirate digital signal processing systems. The backbone structures of multirate systems are digital multirate filter banks. Therefore, efficient multimedia communications rely, in the first place, on real-time implementations of multirate filter banks. In this paper, we describe a Field Programmable Gate Array (FPGA) implementation of the analysis and synthesis filter banks which are the fundamental components of m...
Ali Al-Haj
International Nuclear Information System (INIS)
A movable shield with integral viewing ports, lighting, and remote handling tools operates on a portable track and is used for transferring contaminated filter cartridges from sub-floor filter cells to a transfer cask that is carried on the shield. The system is designed for use in commercial nuclear power plants to reduce operator exposure during filter changes in keeping with US Nuclear Regulatory Commission as-low-as-reasonably-achievable requirements
Composed filter for attenuating bi-frequential noise on LCD-generated ronchigrams
This work aims to design a filter to attenuate high- and medium- frequency noise in optical test images without changing the edges and original characteristics of the test image, generated by traditional filters (spatial or frequential). The noise produced by the LCD pixels (used as a diffraction grating in the Ronchi test) was analyzed. The diffraction is modulated by the spherical wavefront of the mirror under test, generating at least two frequency band noise levels. To reduce this bi-frequential noise, we propose to use an array of filters with the following structure: a low-pass frequential filter LPFF, a band- pass frequential filter BPFF and a circular mask spatial filter CMSF; thus obtaining the composed filter CF=LPFF-(BPFF)(CMSF). Various sizes of filters were used to compare their signal-to-noise ratio against simple filters (low-pass and band-stop).
Mora-González, Miguel; Chiu-Zarate, Roger; Muńoz-Maciel, Jesús; Martinez-Romo, Julio C.; Salinas-Luna, Javier; Campos Colma, Juan; Luna-Rosas, Francisco J.
Preaching in the Lutheran Tradition
DEFF Research Database (Denmark)
 Preaching in the Lutheran tradition The ministry of preaching has traditionally been regarded as the most important characteristic - the sine qua non - of the Lutheran church. Luther characterized preaching as an indispensable means of grace, regarding it central to the church liturgy.  Contemporary Lutheran preachers, however, often find themselves in a dilemma trying to integrate traditional Lutheran ideals with contemporary practical experiences of preaching. The following portrait of preaching in the Lutheran tradition is written from the perspective of the Lutheran Evangelical Church of Denmark. On one hand there is a strong reformed emphasis on the belief that Preadicatio verbi dei est verbum dei - The preaching of the Word of God is the Word of God. On the other hand the majority of preachers cannot easily make themselves advocates for continuing the category, "Word of God", as a homiletical basis. The dialectical theology's attempt of reviving the category, in the middle of the 20th century, led homiletics into too grave difficulties and has been accused of great co-responsibility for the drying out of the church's preaching tradition. The claim that preaching is the Word of God has, in the opinion of many preachers and homileticians, led to too much listener-immune, monological preaching. Yet, Although most preachers struggle to identify with a traditional high homiletics, the continuing study of Luther within Danish theology contributes to a continued consciousness among preachers about the belief that proclamation demands to be understood somehow as the "Word of God".  Udgivelsesdato: October
Lorensen, Marlene Ringgaard
A spectral CT technique using balanced K-edge filter set
In this work, we propose a novel spectral computed tomography (CT) approach that combines a conventional CT scanner with a Ross spectrometer to obtain quasi-monoenergetic measurements. The Ross spectrometer, which is a generalization of a Ross filter pair, is a set of balanced K-edge filters whose thicknesses are such that the transmitted spectra through any two filters are nearly identical except in the energy band between their respective K-edges. The proposed approach is based on these specially designed filters, which are used to synthesize a set of quasi-monoenergetic sinograms whose reconstruction yields energy-dependent attenuation coefficient (?E) images. In this way, we are able to collect data using conventional CT data acquisition electronics, then to synthesize spectral CT datasets with highly stable, rate-independent energy bin boundaries. This approach avoids the chromatic distortion due to event pile-up which can cause difficulties with single photon spectrometry-based methods. To validate our Ross Spectrometer CT concept, we performed phantom studies and acquired data with a balanced filter set consisting of thin foils of silver, tin, cerium, dysprosium and tungsten. For each energy bin, a synthesized quasi-monoenergetic CT image was reconstructed using the filtered back projection (FBP) algorithm operating on the logarithmic ratio of corresponding energy-resolved intensity and blank sinogram pairs. The reconstructed attenuation coefficients showed satisfactorily good agreement with NIST reference values of ?E for water. The proposed spectral CT technique is potentially feasible and holds promise to provide a more accurate and cost-effective alternative to single-photon counting spectral CT techniques.
Rakvongthai, Yothin; Worstell, William; El Fakhri, Georges; Ouyang, Jinsong
Directory of Open Access Journals (Sweden)
Full Text Available This paper gives brief overview of the basic structure and hardware characteristics of the Finite Impulse Response (FIR digital filter.FIR filter has been designed efficiently using matlab and implemented on Field Programmable Gate Array (FPGA platform. MATLAB FDATool has been used to determine filter coefficients and 4th order 32 bit filter has been prototyped. The design has been prototyped on an XC3S500- 4FG320 in Spartan-3E Platform using Integrated Synthesis Environment (ISE 9.1/10.1 Tools all in one design suit from Xilinx.
International Nuclear Information System (INIS)
The invention concerns a mechanical air filter unit and its manufacture, which are suitable for use in nuclear technology. Long filter tubes open at the top, which are glued on the open side to one another and to the box frame in which they are set by hardening plastic resin or organic cement, permit a filtration of much greater quantities of air than filter units of old types of construction having the same dimensions. Further advantages are easy manufacture and lack of mechanical sensitivity to damage. Manufacture of the filter tubes (flushed by fibres via mandrels which are plugged in) and the whole unit are described. (HP)
28. I Kohila keskkoolis kohaspetsiifiline skulptuur ja performance "Filter". Kooli 130. aastapäeva tähistava ettevőtmise eesotsas oli skulptor Paul Rodgers ja kaks viimase klassi noormeest ? Marko Heinmäe, Hendrik Karm.
International Nuclear Information System (INIS)
Purpose: To enable automatic filter operation and facilitate back-washing operation by back-washing filters used in a bwr nuclear power plant utilizing an exhaust gas from a ventilator or air conditioner. Method: Exhaust gas from an exhaust pipe of an ventilator or air conditioner is pressurized in a compressor and then introduced in a back-washing gas tank. Then, the exhaust gas pressurized to a predetermined pressure is blown from the inside to the outside of a filter to thereby separate impurities collected on the filter elements and introduce them to a waste tank. (Furukawa, Y.)
Directory of Open Access Journals (Sweden)
Full Text Available Coalescing filters are widely used throughout industry and improved performance will reduce droplet emissions and operating costs. Experimental observations show orientation of micro fibers in filter media effect the permeability and the separation efficiency of the filter media. In this work two methods are used to align the fibers to alter the filter structure. The results show that axially aligned fiber media improve quality factor on the order of 20% and cutting media on an angle from a thick layered media can improve performance by about 40%. The results also show the improved performance is not monotonically correlated to the average fiber angle of the medium.
R. Bharadwaj
International Nuclear Information System (INIS)
The topics of the nine papers given include the behavior of HEPA filters during exposure to air flows of high humidity as well as of high differential pressure, the development of steel-fiber filters suitable for extreme operating conditions, and the occurrence of various radioactive iodine species in the exhaust air from boiling water reactors. In an introductory presentation the German view of the performance requirements to be met by filters in nuclear facilities as well as the present status of filter quality assurance are discussed. (orig.)
An LLCL Power Filter for Single-Phase Grid-Tied Inverter
DEFF Research Database (Denmark)
This paper presents a new topology of higher order power filter for grid-tied voltage-source inverters, named the LLCL filter, which inserts a small inductor in the branch loop of the capacitor in the traditional LCL filter to compose a series resonant circuit at the switching frequency. Particularly, it can attenuate the switching-frequency current ripple components much better than an LCL filter, leading to a decrease in the total inductance and volume. Furthermore, by decreasing the inductance of a grid-side inductor, it raises the characteristic resonance frequency, which is beneficial to the inverter system control. The parameter design criteria of the proposed LLCL filter is also introduced. The comparative analysis and discussions regarding the traditional LCL filter and the proposed LLCL filter have been presented and evaluated through experiment on a 1.8-kW-single-phase grid-tied inverter prototype.
Wu, Weimin; He, Yuanbin
Empirical Filter Estimation for Subpixel Interpolation and Matching
Digital Repository Infrastructure Vision for European Research (DRIVER)
We study the low-level problem of predicting pixel intensities after subpixel image translations. This is a basic subroutine for image warping and super-resolution, and it has a critical influence on the accuracy of subpixel matching by image correlation. Rather than using traditional frequency-space filtering theory or ad hoc interpolators such as splines, we take an empirical approach, finding optimal subpixel interpolation filters by direct numerical optimization over a large set of traini...
Triggs, Bill
Nonlinear Filter Based Image Denoising Using AMF Approach
Digital Repository Infrastructure Vision for European Research (DRIVER)
This paper proposes a new technique based on nonlinear Adaptive Median filter (AMF) for image restoration. Image denoising is a common procedure in digital image processing aiming at the removal of noise, which may corrupt an image during its acquisition or transmission, while retaining its quality. This procedure is traditionally performed in the spatial or frequency domain by filtering. The aim of image enhancement is to reconstruct the true image from the corrupted image....
Thivakaran, T. K.; Chandrasekaran, Rm
Directory of Open Access Journals (Sweden)
Full Text Available A ballean (equivalently, a coarse structure is an asymptotic counterpart of a uniform topo- logical space.We introduce three new constructions (namely, a ballean-filter mix, a ballean-ideal mix and a filter product of directed sets to give some balleans with extremal properties. In particular, we construct a non-metrizable Frechet group ballean.
O. V. Petrenko
Digital Repository Infrastructure Vision for European Research (DRIVER)
We collected data on the methods, scope, and depth of selective barriers to Internet usage through networks in China. Tests conducted from May through November 2002 indicated at least four distinct and independently operable Internet filtering methods - Web server IP address, DNS server IP address, keyword, and DNS redirection with a quantifiable leap in filtering sophistication beginning in September 2002.
Zittrain, Jonathan L.
Energy Technology Data Exchange (ETDEWEB)
Based on the success of the hyperbaric disc filter in coal preparation ore beneficiation plants, Andritz AG has now developed a hyperbaric drum filter. In addition, the company has developed what it claims to be the first pressure filter to operate with steam. Very fine particles cause several problems in the filtration of coal slurries and mineral concentrates. One drawback is that considerable quantities of liquid are attached to the very fine particles due to the latter's large specific surface area. Furthermore, fine particles also reduce the size of the capillaries in the filter cake, thus increasing the critical pressure which the filtration system has to exceed to achieve the desired final cake moisture. The maximum filtration pressure of conventional vacuum filters is limited by nature itself and by practical aspects to approximately 0.75 bar. The hyperbaric filter combines the continuous operating principle with an increase in filtration pressure of upto 6 bar simply by placing the entire disc or drum filter inside a pressure vessel. Hyperbaric filtration thus combines the continuous operation of conventional vacuum filters with the low final-moisture contents previously only achievable with plate and frame presses.
Directory of Open Access Journals (Sweden)
Full Text Available Features of building and usage sidelobe cancelation filters for phase-shift keyed signal witch generate under the law as well-known code sequences are considered. The result of processing phase-shift keyed signal by means of the synthesized filter for different values of base of a signal is presented.
V. E. Bychkov
Vena cava filter; Vena-cava-Filter
Energy Technology Data Exchange (ETDEWEB)
Fulminant pulmonary embolism is one of the major causes of death in the Western World. In most cases, deep leg and pelvic venous thrombosis are the cause. If an anticoagulant/thrombotic therapy is no longer possible or ineffective, a vena cava filter implant may be indicated if an embolism is threatening. Implantation of the filter is a simple and safe intervention. Nevertheless, it is necessary to take into consideration that the data base for determining the indications for this treatment are very limited. Currently, a reduction in the risk of thromboembolism with the use of filters of about 30%, of recurrences of almost 5% and fatal pulmonary embolism of 1% has been reported, with a risk of up to 20% of filter induced vena cava thrombosis. (orig.) [German] Die fulminante Lungenembolie zaehlt zu den Haupttodesursachen in der westlichen Welt. In der Mehrzahl der Faelle sind tiefe Bein- und Beckenvenenthrombosen ursaechlich verantwortlich. Ist eine antikoagulative/-thrombotische Therapie nicht (mehr) moeglich oder unwirksam, kann bei drohender Emboliegefahr die Vena-cava-Filterimplantation indiziert sein. Die Filterimplantation ist eine einfache und sehr sichere Intervention. Dennoch muss bei der Indikationsstellung beruecksichtigt werden, dass die Datenlage zur Wirksamkeit sehr limitiert ist. So wird aktuell ueber eine Reduktion des Thrombembolierisikos um 30% bei Embolierezidiven von knapp 5% und fatalen Lungenembolien von 1% unter Filterprophylaxe berichtet, bei einem Risiko von bis zu 20% fuer die filterinduzierte Vena-cava-Thrombose. (orig.)
Helmberger, T. [Klinikum Bogenhausen, Institut fuer Diagnostische und Interventionelle Radiologie und Nuklearmedizin, Muenchen (Germany)
Configurable Multirate Filter Banks
Directory of Open Access Journals (Sweden)
Full Text Available Multimedia communications require efficient and real-time implementations of multirate digital signal processing systems. The backbone structures of multirate systems are digital multirate filter banks. Therefore, efficient multimedia communications rely, in the first place, on real-time implementations of multirate filter banks. In this paper, we describe a Field Programmable Gate Array (FPGA implementation of the analysis and synthesis filter banks which are the fundamental components of multirate systems. The implementation utilizes the parallel form of the distributed arithmetic technique which enables maximum exploitation of the parallelism inherent in the multirate filtering operation. Performance results demonstrate the effectiveness of the implementation and suggest that the FPGA platform is indeed attractive for implementing multirate filter banks.
Ali Al-Haj
Energy Technology Data Exchange (ETDEWEB)
Drilling fluids filter cakes are based on a combination of properly graded dispersed particles and polysaccharide polymers. High efficiency filter cakes are formed by these combination , and their formation on wellbore walls during the drilling process has, among other roles, the task of protecting the formation from instantaneous or accumulative invasion of drilling fluid filtrate, granting stability to well and production zones. Filter cake minimizes contact between drilling fluid filtrate and water, hydrocarbons and clay existent in formations. The uniform removal of the filter cake from the entire interval is a critical factor of the completion process. The main methods used to breaking filter cake are classified into two groups, external or internal, according to their removal mechanism. The aim of this work is the presentation of these mechanisms as well their efficiency. (author)
Garcia, Marcelo H.F. [Poland Quimica Ltda., Duque de Caxias, RJ (Brazil)
Energy Technology Data Exchange (ETDEWEB)
Aluminum hydroxide fibers approximately 2 nanometers in diameter and with surface areas ranging from 200 to 650 m.sup.2/g have been found to be highly electropositive. When dispersed in water they are able to attach to and retain electronegative particles. When combined into a composite filter with other fibers or particles they can filter bacteria and nano size particulates such as viruses and colloidal particles at high flux through the filter. Such filters can be used for purification and sterilization of water, biological, medical and pharmaceutical fluids, and as a collector/concentrator for detection and assay of microbes and viruses. The alumina fibers are also capable of filtering sub-micron inorganic and metallic particles to produce ultra pure water. The fibers are suitable as a substrate for growth of cells. Macromolecules such as proteins may be separated from each other based on their electronegative charges.
Tepper, Frederick (Sanford, FL); Kaledin, Leonid (Port Orange, FL)
Energy Technology Data Exchange (ETDEWEB)
An oil filter cartridge for an internal combustion engine is described comprising a container having an inlet connected to the oil circulating system of the engine to receive unfiltered engine oil under pressure from the engine, and an outlet connected back into the oil circulating system or the engine to discharge filtered and reconditioned engine oil back into the engine. The container having a filter material to remove contaminents from the engine oil circulating through the filter material. The filter material being impregnated with specific controlled amounts of certain of the essential additive chemicals that are initially supplied in engine oil by oil manufacturers, to replace a given proportion of those chemicals that are predictably lost in normal engine use over a given period of time, and under given conditions.
Moor, S.E.
In this paper we characterize and construct novel oversampled filter banks implementing fusion frames. A fusion frame is a sequence of orthogonal projection operators whose sum can be inverted in a numerically stable way. When properly designed, fusion frames can provide redundant encodings of signals which are optimally robust against certain types of noise and erasures. However, up to this point, few implementable constructions of such frames were known; we show how to construct them using oversampled filter banks. In this work, we first provide polyphase domain characterizations of filter bank fusion frames. We then use these characterizations to construct filter bank fusion frame versions of discrete wavelet and Gabor transforms, emphasizing those specific finite impulse response filters whose frequency responses are well-behaved.
Chebira, Amina; Mixon, Dustin G
Digital Repository Infrastructure Vision for European Research (DRIVER)
In image processing, denoising is one of the important tasks. Despite the significant research conducted on this topic, the development of efficient denoising methods is still a compelling challenge. In this paper, comparison of Spatial Filters methods with the Homomorphic Filters Methods. The spatial filter methods like Median Filter and Wiener Filter are based on the simple formulas that are proposed by different authors. In Homomorphic Filters Method NormalShrink and BayesShrink are used. ...
Kanwaljeet Kaur; Gurjant Singh; Abhinash Singla
An Amplitude Spectral Capon Estimator with a Variable Filter Length
DEFF Research Database (Denmark)
The filter bank methods have been a popular non-parametric way of computing the complex amplitude spectrum. So far, the length of the filters in these filter banks has been set to some constant value independently of the data. In this paper, we take the first step towards considering the filter length as an unknown parameter. Specifically, we derive a very simple and approximate way of determining the optimal filter length in a data-adaptive way. Based on this analysis, we also derive a model averaged version of the forward and the forward-backward amplitude spectral Capon estimators. Through simulations, we show that these estimators significantly improve the estimation accuracy compared to the traditional Capon estimators.
Nielsen, Jesper Kjær; Smaragdis, Paris
Distortion Parameters Analysis Method Based on Improved Filtering Algorithm
Directory of Open Access Journals (Sweden)
Full Text Available In order to realize the accurate distortion parameters test of aircraft power supply system, and satisfy the requirement of corresponding equipment in the aircraft, the novel power parameters test system based on improved filtering algorithm is introduced in this paper. The hardware of the test system has the characters of s portable and high-speed data acquisition and processing, and the software parts utilize the software Labwindows/CVI as exploitation software, and adopt the pre-processing technique and adding filtering algorithm. Compare with the traditional filtering algorithm, the test system adopted improved filtering algorithm can help to increase the test accuracy. The application shows that the test system with improved filtering algorithm can realize the accurate test results, and reach to the design requirements.
ZHANG Shutuan
Circular filter bag change ladderack system video presentation
International Nuclear Information System (INIS)
A great deal of research and development at Harwell over the last few years has centered around the design of circular radial flow HEPA filters as alternatives to the traditional rectangular HEPA filter. With a circular insert there are inherent features which give this geometry certain advantages over its counterpart, such as ease of sealing, compatibility with remote handling and disposal routes; these have been well publicized in previous works. A mock-up is shown of a bag change ladderack system of 3400m3/h circular filter. It highlights the space requirements for bag changing and demonstrates the ease with which a filter may be replaced. The filter throat incorporates a silicone rubber lip seal which forms a flap seal against a tapered spigot feature built into the wall. The novelty of this filter design is that the bag is an integral part of the filter and is attached onto the filter flange. This enables the inside of the filter, where the contamination particulate has collected, to be sealed/bagged off and hence the dust burden retained
Multi-layer filtering approach for hyperspectral target detection
Target detection is an important application in hyperspectral image processing field. In this paper, we propose a new target detection method incorporates the idea of using multi-layer spectral filters, which aims to boost the performance of the traditional detection methods. The proposed algorithm enhances the targets and suppresses the undesired backgrounds through a layer-by-layer filtering procedure. Several second-order algorithms for hyperspectral target detection have been proposed, such as Matched Filter (MF), Constrained Energy Minimization (CEM) and Adaptive Coherence Estimator (ACE). In this paper, a basic second-order filter detector such as CEM, MF and ACE is used to filter the spectral data. After each layer of filtering, we transform the spectral vectors with a nonlinear function based on the previous layer's filtering results. Through the layer-by-layer filtering process, we obtain the gradually increasing improvements of the detection performance. Experimental results for detecting targets in real hyperspectral image are presented with our multi-layer filtering approach. Our method suggests significant advantages on real hyperspectral data, and improves the performance of the classical second-order algorithms, such as CEM, MF and ACE.
Zou, Zhengxia; Shi, Zhenwei
Smoke and pollutant filtering device
International Nuclear Information System (INIS)
A smoke and pollutant filtering device comprising a mask having a filter composed of a series of contiguous, serial layers of filtering material. The filter consists of front and rear gas permeable covers, a first filter layer of pressed vegetable matter, a second filter layer comprising a layer of activated charcoal adjacent a layer of aqua filter floss, a third filter comprising a gas permeable cloth situated between layers of pressed vegetable matter, and a fourth filter layer comprising an aqua filter floss. The first through fourth filter layers are sandwiched between the front and rear gas permeable covers. The filtering device is stitched together and mounted within a fireretardant hood shaped to fit over a human head. Elastic bands are included in the hood to maintain the hood snugly about the head when worn
A Simple Heteroscedasticity Removing filter
Digital Repository Infrastructure Vision for European Research (DRIVER)
In this paper variance stabilizing filters are discussed. A new filter with nice properties is proposed which makes use of moving averages and moving standard deviations, the latter smoothed with the Hodrick-Prescott filter. This filter is compared to a GARCH-type filter. An ARIMA model is estimated for the filtered GDP series, and the parameter estimates are used in forecasting the unfiltered series. These forecasts compare well with those of ARIMA, ARFIMA and GARCH models based on the unfil...
Stockhammar, Pa?r; O?ller, Lars-erik
Individualizing in Traditional Classroom Settings.
Effective individualized instruction depends primarily on the teacher possessing the skills to implement it. Individualization is therefore quite compatible with the traditional self-contained elementary classroom model, but not with its alternative, departmentalization, which allows teachers neither the time flexibility nor the familiarity with…
Thornell, John G.
Does Scottish Education Need Traditions?
Scottish education was, until quite recently, the conscious product of liberal tradition, of the belief by influential elites that the nation's educational history was strong, coherent, and progressive, a source of economic flexibility, of modernising ideas, and of liberal opportunity. In recent decades, however, it has become fashionable to decry…
Paterson, Lindsay
With today's electrical and electronics systems requiring increased levels of performance and reliability, the design of robust EMI filters plays a critical role in EMC compliance. Using a mix of practical methods and theoretical analysis, EMI Filter Design, Third Edition presents both a hands-on and academic approach to the design of EMI filters and the selection of components values. The design approaches covered include matrix methods using table data and the use of Fourier analysis, Laplace transforms, and transfer function realization of LC structures. This edition has been fully revised
Ozenbaugh, Richard Lee
Multilevel filtering elliptic preconditioners
A class of preconditioners is presented for elliptic problems built on ideas borrowed from the digital filtering theory and implemented on a multilevel grid structure. They are designed to be both rapidly convergent and highly parallelizable. The digital filtering viewpoint allows the use of filter design techniques for constructing elliptic preconditioners and also provides an alternative framework for understanding several other recently proposed multilevel preconditioners. Numerical results are presented to assess the convergence behavior of the new methods and to compare them with other preconditioners of multilevel type, including the usual multigrid method as preconditioner, the hierarchical basis method and a recent method proposed by Bramble-Pasciak-Xu.
Kuo, C. C. Jay; Chan, Tony F.; Tong, Charles
New design of orthogonal filter banks using the Cayley transform
It is a challenging task to design orthogonal filter banks, especially multidimensional (MD) ones. In the one-dimensional (1D) two-channel finite impulse response (FIR) filter bank case, several design methods exist. Among them, designs based on spectral factorizations (by Smith and Barnwell) and designs based on lattice factorizations (by Vaidynanathan and Hoang) are the most effective and widely used. The 1D two-channel infinite impulse response (IIR) filter banks and associated wavelets were considered by Herley and Vetterli. All of these design methods are based on spectral factorization. Since in multiple dimensions, there is no factorization theorem, traditional 1D design methods fail to generalize. Tensor products can be used to construct MD orthogonal filter banks from 1D orthogonal filter banks, yielding separable filter banks. In contrast to separable filter banks, nonseparable filter banks are designed directly, and result in more freedom and better frequency selectivity. In the FIR case, Kovacevic and Vetterli designed specific two-dimensional and three-dimensional nonseparable FIR orthogonal filter banks. In the IIR case, there are few design results (if any) for MD orthogonal IIR filter banks. To design orthogonal filter banks, we must design paraunitary matrices, which leads to solving sets of nonlinear equations. The Cayley transform establishes a one-to-one mapping between paraunitary matrices and para-skew-Hermitian matrices. In contrast to nonlinear equations, the para-skew-Hermitian condition amounts to linear constraints on the matrix entries which are much easier to solve. We present the complete characterization of both paraunitary FIR matrices and paraunitary IIR matrices in the Cayley domain. We also propose efficient design methods for MD orthogonal filter banks and corresponding methods to impose the vanishing-moment condition.
Zhou, Jianping; Do, Minh N.; Kovacevic, Jelena
Traditional and non-traditional refractories for heat exchangers
Energy Technology Data Exchange (ETDEWEB)
The article briefly reviews the history of refractories employed for the construction of both recuperative and regenerative heat exchangers. New ceramic materials suitable for the construction of recuperators used in sectors other than traditional metallurgy, that operate at high temperatures and in the presence of high working pressures and/or corrosive atmospheres, are discussed. Finally, the activities of Ansaldo Ricerche (Italy) in this sector are reported.
Aliprandi, G.; Corbellini, F.; Mao, C. (Genoa Univ. (Italy). Ist. di Ingegneria Chimica Ansaldo Ricerche, Genoa (Italy))
International Nuclear Information System (INIS)
Fulminant pulmonary embolism is one of the major causes of death in the Western World. In most cases, deep leg and pelvic venous thrombosis are the cause. If an anticoagulant/thrombotic therapy is no longer possible or ineffective, a vena cava filter implant may be indicated if an embolism is threatening. Implantation of the filter is a simple and safe intervention. Nevertheless, it is necessary to take into consideration that the data base for determining the indications for this treatment are very limited. Currently, a reduction in the risk of thromboembolism with the use of filters of about 30%, of recurrences of almost 5% and fatal pulmonary embolism of 1% has been reported, with a risk of up to 20% of filter induced vena cava thrombosis. (orig.)
Generalized Filtering Decomposition
Digital Repository Infrastructure Vision for European Research (DRIVER)
This paper introduces a new preconditioning technique that is suitable for matrices arising from the discretization of a system of PDEs on unstructured grids. The preconditioner satisfies a so-called filtering property, which ensures that the input matrix is identical with the preconditioner on a given filtering vector. This vector is chosen to alleviate the effect of low frequency modes on convergence and so decrease or eliminate the plateau which is often observed in the convergence of iter...
Complex Hilbert Transform Filter
Digital Repository Infrastructure Vision for European Research (DRIVER)
Hilbert transform is a basic tool in constructing analytical signals for a various applications such as amplitude modulation, envelope and instantaneous frequency analysis, quadrature decoding, shift-invariant multi-rate signal processing and Hilbert-Huang decomposition. This work introduces a complex Hilbert transform (CHT) filter, where the real and imaginary parts are a Hilbert transform pair. The CHT filtered signal is analytic, i.e. its Fourier transform is zero in negative frequency ran...
Digital Repository Infrastructure Vision for European Research (DRIVER)
A Bloom filter is a method for reducing the space (memory) required for representing a set by allowing a small error probability. In this paper we consider a \\emph{Sliding Bloom Filter}: a data structure that, given a stream of elements, supports membership queries of the set of the last $n$ elements (a sliding window), while allowing a small error probability. We formally define the data structure and its relevant parameters and analyze the time and memory requirements need...
Naor, Moni; Yogev, Eylon
A comparative study on the performance of asbestos-free depth-filters for removal of pyrogens from infusion fluids.
Three asbestos-free depth-filters were compared with traditionally used asbestos-containing depth-filters for chemical integrity, physical integrity and pyrogen retention. With chemical and physical integrity only minor differences between the various filter types were seen. One asbestos-free depth-filter, based on charcoal, showed poor pyrogen-retention; this might be due to a high flow rate used. Asbestos-free depth-filters based on kieselguhr or on a mixture of kaolin and alumina proved to be good alternatives; these filters have proved to be suitable for the removal of pyrogens from electrolyte- or carbohydrate-containing infusion fluids. PMID:6118405
Baggerman, C; Brandsema, C; Humer, M; Visser, J
Traditional transfusion practices are changing
Digital Repository Infrastructure Vision for European Research (DRIVER)
Schochl and co-authors have described a 5-year retrospective study that outlines a novel, important and controversial transfusion concept in seriously injured trauma patients. Traditionally, clinicians have been taught to use a serial approach, resuscitating hypovolemic trauma patients with a form of crystalloid or colloid, followed by red blood cells (RBCs), then fresh frozen plasma (FFP), and lastly platelets. The data supporting this widely accepted approach are remarkably weak. Conversely...
Holcomb, John B.
The Promise of Traditional Medicines
Digital Repository Infrastructure Vision for European Research (DRIVER)
The usage of plants, plant extracts or plant-derived pure chemicals to treat disease become a therapeutic modality, which has stood the test of time. Today several pharmacological classes of drugs include a natural product prototype. Aspirin, atropine, ephedrine, digoxin, morphine, quinine, reserpine and tubocurarine are a few examples of modern drugs, which were originally discovered through the study of traditional cures and folk knowledge of indigenous people. A team work amongst ethnobota...
Ansari, J. A.; Inamdar, N. N.
Ginseng in Traditional Herbal Prescriptions
Digital Repository Infrastructure Vision for European Research (DRIVER)
Panax ginseng Meyer has been widely used as a tonic in traditional Korean, Chinese, and Japanese herbal medicines and in Western herbal preparations for thousands of years. In the past, ginseng was very rare and was considered to have mysterious powers. Today, the efficacy of drugs must be tested through well-designed clinical trials or meta-analyses, and ginseng is no exception. In the present review, we discuss the functions of ginseng described in historical documents and describe how thes...
Park, Ho Jae; Kim, Dong Hyun; Park, Se Jin; Kim, Jong Min; Ryu, Jong Hoon
Traditional communities, multinationals and biodiversity
Digital Repository Infrastructure Vision for European Research (DRIVER)
The Iratapuru Sustainable Development Reserve is mainly exploited by the community of the Săo Francisco village. Due to its efforts to organize its members around a production co-operative and to improve their standard of living, but also as a result of massive funding from local and international institutions, this community has become a symbol for the actions of sustainable development undertaken with and in the benefit of « traditional » communities living in protected areas in the Amaz...
Greissing, Anna; Le Tourneau, Franc?ois-michel
Augustine and the phenomenological tradition
Digital Repository Infrastructure Vision for European Research (DRIVER)
This essay traces the reception of Augustine in the 20th and 21st century phenomenological tradition. It gives special attention to recent monographs on Augustine by Jean-Luc Marion and Jean-Louis Chrétien, but contextualises these both fore (by examining the earlier work of Edmund Husserl and Martin Heidegger, as well as earlier and less determinative Augustinian engagements by Marion and Chrétien) and aft (by critically considering the philosophical, philological and theological implicati...
Biebighauser, Jeffrey
Two Thoughts about Traditional Knowledge
Digital Repository Infrastructure Vision for European Research (DRIVER)
Fisher argues the traditional knowledge of environmentalism and the public domain ideas by presenting two combined related themes involving the British colonist of Native Americans. The idea of devaluing the Indian's nonacquisitive, natural, respectful way of living lightly upon the land while conserving it, and fostering imperialism and unjust conquest. Among other things, he formulates three parallel provisions to the TRIPS Agreement to increase the leverage of the countries in determining ...
Fisher, William W.
Post-traditional corporate governance
Digital Repository Infrastructure Vision for European Research (DRIVER)
Traditional definitions of corporate governance are narrow, focusing on legal relations between managers and shareholders. More recent definitions extend the boundaries of governance to consider the role that various stakeholders play in shaping the behaviour of firms. While stakeholding theory embraces a broader set of corporate constituencies, our argument in this paper is that even these definitions are too narrow – they lack the analytical capacity to account for the social embeddedness...
Mason, Michael; O Mahony, Joan
Post-traditional corporate governance
Digital Repository Infrastructure Vision for European Research (DRIVER)
Traditional definitions of corporate governance are narrow, focusing on legal relations between managers and shareholders. More recent definitions extend the boundaries of governance to consider the role that various stakeholders play in shaping the behaviour of firms. While stakeholder theory embraces a broader set of corporate constituencies, our argument in this paper is that even these definitions are too narrow—they lack the analytical capacity to account for the social embeddedness an...
Mason, Michael; O Mahony, Joan
Digital Repository Infrastructure Vision for European Research (DRIVER)
This paper describes the traditional methods of preparing fermented foods and beverages of Lesotho. Information on the preparation methods was obtained through a combination of literature review and face to face interviews with respondents from Roma in Lesotho. An unstructured questionnaire was used to capture information on the processes, raw materials and utensils used. Four products; motoho (a fermented porridge), Sesotho (a sorghum based alcoholic beverage), hopose (sorghum fermented beer...
Traditional methods for enteric virus removal from waters involve filtering the water through a positively charged filter followed by elution with beef extract, second step concentration by flocculation, and assay in cell culture. Two of the problems associated with this method ...
Insomnia in Iranian Traditional Medicine
Context: Insomnia is one of the most prevalent sleep disorders characterized by sleep difficulty that impairs daily functioning and reduces quality of life. The burden of medical, psychiatric, interpersonal, and societal consequences of insomnia expresses the importance of diagnosing and treatment of insomnia. The aim of study was to investigate causes of insomnia from the viewpoint of Iranian traditional medicine. Evidence Acquisition: In this review study, we searched insomnia in a few of the most famous ancient textbooks of Iranian traditional medicine from different centuries. This books includeThe Canon of Medicine by Avicenna (the first version of Beirut), Zakhire Kharazmshahi by Jurjani (the scanned version of Bonyade Farhang-e Iran), Malfaregh by Razes (the first version of Iran University of Medical Sciences), and Aqili's cure by Aqili (the first version of Iran University of Medical Sciences). Results: This study found that in Iranian traditional medicine manuscripts, insomnia was called sahar and even though many factors induce insomnia, most of them act through causing brain dystemperament. Conclusions: The brain dystemperament is considered one of the main causes of insomnia and insomnia can be well managed with an organized line of treatment, by correcting the brain dystemperament through elimination of causes. This study helps to find new solutions to treat insomnia.
Feyzabadi, Zohre; Jafari, Farhad; Feizabadi, Parvin Sadat; Ashayeri, Hassan; Esfahani, Mohammad Mahdi; Badiee Aval, Shapour
A Robust Collaborative Filtering Recommendation Algorithm Based on Multidimensional Trust Model
Digital Repository Infrastructure Vision for European Research (DRIVER)
Collaborative filtering is one of the widely used technologies in the e-commerce recommender systems. It can predict the interests of a user based on the rating information of many other users. But the traditional collaborative filtering recommendation algorithm has the problems such as lower recommendation precision and weaker robustness. To solve these problems, in this paper we present a robust collaborative filtering recommendation algorithm based on multidimensional trust model. Firstly,...
Dongyan Jia; Fuzhi Zhang; Sai Liu
A new Approach for Kalman filtering on Mobile Robots in the presence of uncertainties
Digital Repository Infrastructure Vision for European Research (DRIVER)
In many practical Kalman filter applications, the quantity of most significance for the estimation error is the process noise matrix. When filters are stabilized or performance is sought to be improved, tuning of this matrix is the most common method. This tuning process cannot be done before the filter is implemented, as it is primarily made necessary by modelling errors. In this paper, two different methods for modelling the process noise are described and evaluated; a traditional one based...
Larsen, Thomas Dall; Andersen, Nils Axel; Ravn, Ole
Comparative Study of Target Function Definition in Linear Phase FIR Filter Design
Digital Repository Infrastructure Vision for European Research (DRIVER)
The Weighted Least Squares (WLS) principle is popular in filter design due to its flexibility, where it can output equiripple filters with appropriate target function and weighted function. Therefore, this research studies the influence of the target function in linear phase Finite-Impulse-Response (FIR) filter design by comparing different target functions in WLS iterations. Compared with the traditional one, simulations show that the proposed target function can obtain more accurate stopban...
Jingyu Hua; Zheng Gao; Wankun Kuang; Zhijiang Xu; Chengfeng Ruan
A High Precision Selective Harmonic Compensation Scheme for Active Power Filters
Digital Repository Infrastructure Vision for European Research (DRIVER)
This study proposes a high precision selective harmonic compensation scheme for active power filters, which compensates selective current harmonics detected by Kalman filter and harmonic current is tracked by a novel PI controller-recursive integral PI controller. As Kalman filter can detect each order harmonic separately, the compensation on delay time arouse from digital implementation is performed. Since traditional PI is subjected to inherent steady-state error, a recursive integral...
Geng Tao; Li Baoshen; Zhao Jin
CMS Event Filter Farm Software
The CMS trigger system consists of a two stage system: A first level trigger system and a large farm of processors performing the online event filtering. The presented paper gives an overview of the current status of development of the filter farm software. We present an architectural model for efficient filter farm software and show a multi - threaded event filter prototype.
Kruse, A
Computing a Comprehensible Model for Spam Filtering
In this paper, we describe the application of the Desicion Tree Boosting (DTB) learning model to spam email filtering.This classification task implies the learning in a high dimensional feature space. So, it is an example of how the DTB algorithm performs in such feature space problems. In [1], it has been shown that hypotheses computed by the DTB model are more comprehensible that the ones computed by another ensemble methods. Hence, this paper tries to show that the DTB algorithm maintains the same comprehensibility of hypothesis in high dimensional feature space problems while achieving the performance of other ensemble methods. Four traditional evaluation measures (precision, recall, F1 and accuracy) have been considered for performance comparison between DTB and others models usually applied to spam email filtering. The size of the hypothesis computed by a DTB is smaller and more comprehensible than the hypothesis computed by Adaboost and Naďve Bayes.
Ruiz-Sepúlveda, Amparo; Trivińo-Rodriguez, José L.; Morales-Bueno, Rafael
Active flutter suppression using dipole filters
By using traditional control concepts of gain root locus, the active suppression of a flutter mode of a flexible wing is examined. It is shown that the attraction of the unstable mode towards a critical system zero determines the degree to which the flutter mode can be stabilized. For control situations where the critical zero is adversely placed in the complex plane, a novel compensation scheme called a 'Dipole' filter is proposed. This filter ensures that the flutter mode is stabilized with acceptable control energy. The control strategy is illustrated by designing flutter suppression laws for an active flexible wing (AFW) wind-tunnel model, where minimal control effort solutions are mandated by control rate saturation problems caused by wind-tunnel turbulence.
Srinathkumar, S.; Waszak, Martin R.
State space second order filter estimation
Scientific Electronic Library Online (English)
Full Text Available SciELO Mexico | Language: English Abstract in english The second order stochastic filter is based on difference models with uncorrelated innovation conditions structured in state space having stationary properties through a surface with bounded drift around the mean value. This allows building recursive estimation without generality lost and basic prop [...] erties over the stochastic state space surface with unknown gains viewed as a black-box scheme. The spatial region generated gave an approximation to real parametres set with a sufficient convergence rate in a probability sense. The results were applied in adaptive identification states with a high convergence rate, observed in the functional error described illustratively in simulations. This technique was developed over the smooth slide surface having advantages over other traditional filters.
J.J, Medel; M. T., Zagaceta.
Generic Hardware Architectures for Sampling and Resampling in Particle Filters
Directory of Open Access Journals (Sweden)
Full Text Available Particle filtering is a statistical signal processing methodology that has recently gained popularity in solving several problems in signal processing and communications. Particle filters (PFs have been shown to outperform traditional filters in important practical scenarios. However their computational complexity and lack of dedicated hardware for real-time processing have adversely affected their use in real-time applications. In this paper, we present generic architectures for the implementation of the most commonly used PF, namely, the sampling importance resampling filter (SIRF. These provide a generic framework for the hardware realization of the SIRF applied to any model. The proposed architectures significantly reduce the memory requirement of the filter in hardware as compared to a straightforward implementation based on the traditional algorithm. We propose two architectures each based on a different resampling mechanism. Further, modifications of these architectures for acceleration of resampling process are presented. We evaluate these schemes based on resource usage and latency. The platform used for the evaluations is the Xilinx Virtex II pro FPGA. The architectures presented here have led to the development of the first hardware (FPGA prototype for the particle filter applied to the bearings-only tracking problem.
Petar M. Djuri?
Intraindividual evaluation of the influence of iterative reconstruction and filter kernel on subjective and objective image quality in computed tomography of the brain
Energy Technology Data Exchange (ETDEWEB)
Objectives: To intraindividually evaluate the potential of 4th generation iterative reconstruction (IR) on brain CT with regard to subjective and objective image quality. Methods: 31 consecutive raw data sets of clinical routine native sequential brain CT scans were reconstructed with IR level 0 (= filtered back projection), 1, 3 and 4; 3 different brain filter kernels (smooth/standard/sharp) were applied respectively. Five independent radiologists with different levels of experience performed subjective image rating. Detailed ROI analysis of image contrast and noise was performed. Statistical analysis was carried out by applying a random intercept model. Results: Subjective scores for the smooth and the standard kernels were best at low IR levels, but both, in particular the smooth kernel, scored inferior with an increasing IR level. The sharp kernel scored lowest at IR 0, while the scores substantially increased at high IR levels, reaching significantly best scores at IR 4. Objective measurements revealed an overall increase in contrast-to-noise ratio at higher IR levels, which was highest when applying the soft filter kernel. The absolute grey-white contrast decreased with an increasing IR level and was highest when applying the sharp filter kernel. All subjective effects were independent of the raters' experience and the patients' age and sex. Conclusion: Different combinations of IR level and filter kernel substantially influence subjective and objective image quality of brain CT. (orig.)
Buhk, J.H. [Univ. Medical Center, Hamburg-Eppendorf (Germany). Dept. of Neuroradiology; Laqmani, A.; Schultzendorff, H.C. von; Hammerle, D.; Adam, G.; Regier, M. [Univ. Medical Center, Hamburg-Eppendorf (Germany). Dept. of Diagnostic and Interventional Radiology; Sehner, S. [Univ. Medical Center, Hamburg-Eppendorf (Germany). Inst. of Medical Biometry and Epidemiology; Fiehler, J. [Univ. Medical Center, Hamburg-Eppendorf (Germany). Neuroradiology; Nagel, H.D. [Dr. HD Nagel, Science and Technology for Radiology, Buchholz (Germany)
Modernism and tradition and the traditions of modernism
Directory of Open Access Journals (Sweden)
Full Text Available Conventionally, the story of musical modernism has been told in terms of a catastrophic break with the (tonal past and the search for entirely new techniques and modes of expression suitable to a new age. The resulting notion of a single, linear, modernist mainstream (predicated on the basis of a Schoenbergian model of musical progress has served to conceal a more subtle relationship between past and present. Increasingly, it is being recognized that there exist many modernisms and their various identities are forged from a continual renegotiation between past and present, between tradition(s and the avant-garde. This is especially relevant when attempting to discuss the reception of modernism outside central Europe, where the adoption of (Germanic avant-garde attitudes was often interpreted as being "unpatriotic". The case of Great Britain is examined in detail: Harrison Birtwistle's opera The Mask of Orpheus (1973–83 forms the focus for a wider discussion of modernism within the context of late/post-modern thought.
Kros Džonatan
Spatial filters for focusing ultrasound images
DEFF Research Database (Denmark)
Traditionally focusing is done by taking out one sample in the received signal from each transducer element and then sum these signals. This method does not take into account the temporal or spatial spread of the received signal from a point scatterer and does not make an optimal focus of the data. A new method for making spatial matched filter focusing of RF ultrasound data is proposed based on the spatial impulse response description of the imaging. The response from a scatterer at any given point in space relative to the transducer can be calculated, and this gives the spatial matched filter for beamforming the received RF signals from the individual transducer elements. The matched filter is applied on RF signals from individual transducer elements, thus properly taking into account the spatial spread of the received signal. The method can be applied to any transducer and can also be used for synthetic aperture imaging for single element transducers. It is evaluated using the Field II program. Data from asingle 3 MHz transducer focused at a distance of 80 mm is processed. Far from the transducer focal region, the processing greatly improves the image resolution: the lateral slice of the autocovariance function of the image shows a -6 dB width reduction by a factor of 3.3 at 20 mm and by a factor of 1.8 at 30 mm. Other simulations use a 64 elements, 3 MHz, linear array. Different receiving conditions are compared and this shows that the effect of the filter is progressively lower, but the approach always yields point spread functions better or equal to a traditional dynamically focused image. Finally, the process was applied to in-vivo clinical images of the liver and right kidney from a 28 years old male. The data was obtained with a single element transducer focused at 100 mm. The improvement in resolution was in this case less evident and further optimization is needed.
Jensen, Jørgen Arendt
International Nuclear Information System (INIS)
This standard establishes essential elements of a Department of Energy (DOE) program for testing HEPA filters to be installed in DOE nuclear facilities or used in DOE-contracted activities. A key element is the testing of HEPA filters for performance at a DOE Filter Test Facility (FTF) prior to installation. Other key elements are (1) providing for a DOE HEPA filter procurement program, and (2) verifying that HEPA filters to be installed in nuclear facilities appear on a Qualified Products List (QPL)
Filters for Submillimeter Electromagnetic Waves
New manufacturing process produces filters strong, yet have small, precise dimensions and smooth surface finish essential for dichroic filtering at submillimeter wavelengths. Many filters, each one essentially wafer containing fine metal grid made at same time. Stacked square wires plated, fused, and etched to form arrays of holes. Grid of nickel and tin held in brass ring. Wall thickness, thickness of filter (hole depth) and lateral hole dimensions all depend upon operating frequency and filter characteristics.
Berdahl, C. M.
Multilevel Mixture Kalman Filter
Directory of Open Access Journals (Sweden)
Full Text Available The mixture Kalman filter is a general sequential Monte Carlo technique for conditional linear dynamic systems. It generates samples of some indicator variables recursively based on sequential importance sampling (SIS and integrates out the linear and Gaussian state variables conditioned on these indicators. Due to the marginalization process, the complexity of the mixture Kalman filter is quite high if the dimension of the indicator sampling space is high. In this paper, we address this difficulty by developing a new Monte Carlo sampling scheme, namely, the multilevel mixture Kalman filter. The basic idea is to make use of the multilevel or hierarchical structure of the space from which the indicator variables take values. That is, we draw samples in a multilevel fashion, beginning with sampling from the highest-level sampling space and then draw samples from the associate subspace of the newly drawn samples in a lower-level sampling space, until reaching the desired sampling space. Such a multilevel sampling scheme can be used in conjunction with the delayed estimation method, such as the delayed-sample method, resulting in delayed multilevel mixture Kalman filter. Examples in wireless communication, specifically the coherent and noncoherent 16-QAM over flat-fading channels, are provided to demonstrate the performance of the proposed multilevel mixture Kalman filter.
Xiaodong Wang
International Nuclear Information System (INIS)
Filter elements in a housing are used to filter particles from waste gas before it is discharged from radioactive waste processing plant. When the elements are clogged they are cleaned by a reverse flow of liquid, delivered through a valve while venting off the gas, until the housing is full of liquid. Then compressed air is delivered through a valve, above the liquid, and a drain valve is opened, to force the liquid through the filter elements and out of the housing. Elements are HEPA or ULPA rated and preferably of sintered metal fibres. The backwash liquid may be water with or without surfactant, caustic soda, nitric acid or organic solvent, and helps to remove small particles by neutralising electrostatic forces holding them in the filter element pores. The liquid and air are both delivered to the housing through filters which are rated at least as finely pored as the HEPA or ULPA elements. Used backwash liquid is collected for further treatment. Several housings may operate in parallel and be cleaned in sequence. (Author)
Energy Technology Data Exchange (ETDEWEB)
Filter elements in a housing are used to filter particles from waste gas before it is discharged from radioactive waste processing plant. When the elements are clogged they are cleaned by a reverse flow of liquid, delivered through a valve while venting off the gas, until the housing is full of liquid. Then compressed air is delivered through a valve, above the liquid, and a drain valve is opened, to force the liquid through the filter elements and out of the housing. Elements are HEPA or ULPA rated and preferably of sintered metal fibres. The backwash liquid may be water with or without surfactant, caustic soda, nitric acid or organic solvent, and helps to remove small particles by neutralising electrostatic forces holding them in the filter element pores. The liquid and air are both delivered to the housing through filters which are rated at least as finely pored as the HEPA or ULPA elements. Used backwash liquid is collected for further treatment. Several housings may operate in parallel and be cleaned in sequence. (Author).
Seibert, J.M.; Sobel, Nelson; Weber, L.D.
Impact of zooming and filtering on gated myocardial perfusion SPECT in patients with small hearts
Directory of Open Access Journals (Sweden)
Full Text Available Objectives: Underestimation of end-diastolic volume (EDV, end-systolic volume(ESV and overestimation of left ventricular ejection fraction(LVEF in patients with small hearts is a reported problem of the gated SPECT. The aim of this study was to evaluate the influence of zooming and filtering on left ventricular function parameters measurements in patients with small hearts. Methods: Thirty patients with small hearts (ESV?25 ml using acquisition zoom of 1.45 and cut-off frequency 0.35 cycle/cm were collected for the study. All patients underwent rest Tc-99m Sestamibi gated myocardial perfusion SPECT using acquisition zooms of 1.45 and 1.78 consecutively. After reconstruction by filtered back-projection(Butterworth, 0.35, 0.40, 0.45, 0.50 and 0.55 cycles/cm cut-off, order 5, LVEF, EDV and ESV were computed using quantitative gated SPECT (QGS program. Results: Good correlation was noticed between two methods of acquisition. EDV and ESV using acquisition zoom of 1.78 were significantly higher than EDV and ESV by zoom of 1.45 respectively. However, LVEF using zoom of 1.45 was overestimated compared with LVEF by zoom of 1.78. By increasing the cut-off frequency of the Butterworth filter from a smooth 0.35 to a sharper 0.55cycles/cm, larger volumes and a significant decrease in LVEF were obtained by QGS. Mean difference of LVEF between two methods of acquisition (zooms of 1.78 and 1.45 were significantly different between different filtering (P<0.001. As the cut-off frequency of the filter was increased, change in the LV volumes and LVEF is decreased. Difference in LVEF between two acquisition zooms was decreased by sharper cut-off frequencies. Thus effect of zooming on measurement of LVEF in higher cut-off frequencies is decreased. On the other hand, effect of cut-off frequency in LVEF value is decreased in higher zoom as compared to the lower zoom. Conclusion: Filtering and zooming greatly influenced EDV, ESV and LVEF measurements. Increasing in zooming or filter cut-off frequency results higher LV volumes but lower LVEF. A higher zooming and/or a sharper filter might be suggested for quantitative gated SPECT in patients with a small heart.
V.R. Dabbagh Kakhki
Toward Directly-Deposited Optical Blocking Filters for High-performance, Back-illuminated Imaging X-ray Detectors
Silicon X-ray detectors require optical blocking filters to prevent out-of-band (UV, visible and near-IR) radiation from corrupting the X-ray signal. Traditionally, blocking filters have been deposited on thin, free-standing membranes suspended over the detector. Free-standing filters are fragile, however, and in past instruments have required heavy and complex vacuum housings to protect them from acoustic loads during ground operations and launch. A directly-deposited blocking filter greatly simplifies the instrument and in principle permits better soft X-ray detection efficiency than a traditional free-standing filter. Directly-deposited filters have flown in previous generation instruments (e.g. the XMM/Newton Reflection Grating Spectrometer) but none has yet been demonstrated on a modern, high-performance back-illuminated X-ray CCD. We report here on the status of our NASA-funded Strategic Astrophysics Technology program to demonstrate such filters.
Bautz, Mark W.; Kissel, S. E.; Ryu, K.; Suntharalingam, V.
Morphing Ensemble Kalman Filters
A new type of ensemble filter is proposed, which combines an ensemble Kalman filter (EnKF) with the ideas of morphing and registration from image processing. This results in filters suitable for nonlinear problems whose solutions exhibit moving coherent features, such as thin interfaces in wildfire modeling. The ensemble members are represented as the composition of one common state with a spatial transformation, called registration mapping, plus a residual. A fully automatic registration method is used that requires only gridded data, so the features in the model state do not need to be identified by the user. The morphing EnKF operates on a transformed state consisting of the registration mapping and the residual. Essentially, the morphing EnKF uses intermediate states obtained by morphing instead of linear combinations of the states.
Beezley, Jonathan D
Energy Technology Data Exchange (ETDEWEB)
Just as linear models generalize the sample mean and weighted average, weighted order statistic models generalize the sample median and weighted median. This analogy can be continued informally to generalized additive modeels in the case of the mean, and Stack Filters in the case of the median. Both of these model classes have been extensively studied for signal and image processing but it is surprising to find that for pattern classification, their treatment has been significantly one sided. Generalized additive models are now a major tool in pattern classification and many different learning algorithms have been developed to fit model parameters to finite data. However Stack Filters remain largely confined to signal and image processing and learning algorithms for classification are yet to be seen. This paper is a step towards Stack Filter Classifiers and it shows that the approach is interesting from both a theoretical and a practical perspective.
Porter, Reid B [Los Alamos National Laboratory; Hush, Don [Los Alamos National Laboratory
Energy Technology Data Exchange (ETDEWEB)
Companies planning construction or replacement of filtration equipment also can turn to consultants, bag makers and specialty conferences for more information. Or take advantage of a free fax service (302-999-4541) introduced to North America in late 1992 by Du Pont Co. of Wilmington, Del., a supplier of the fibers used in fabric filter bags. With specifics on operating conditions, the Filter Advisor database can recommend fibers for hot gas filtration applications, and estimate bag life, pressure drop and emissions. Filter Advisor uses performance data for Nomex, Teflon and Tefaire synthetic fibers in actual field installations. Data on more than 20 installation types are available, including cement, ceramic, iron, incinerator, spray dryer and boiler. This product guide is the third in a series of guides to give readers a sampling of suppliers and their products for specific environmental applications.
Nudo, L.
We consider using a Wiener filter for denoising a set of input signals that is degraded by additive white Gaussian noise. The Wiener filter is designed to minimize the mean square error, and it requires the knowledge of covariance of input signals and variance of the noise. The mean square error is defined as a distance between input signals and input signals estimated by the Wiener filter from noisy output signals. Although we have to infer input signals from only noisy output signals, the input signals are required for the evaluation of the mean square error. We reformulate the mean square error using noisy output signals and the covariance of the input signals. The covariance of the input signals is estimated by minimizing the mean square error. We apply our method to the case when an input signal is not generated by the assumed prior probability. In particular, we apply our method to image restoration and obtain good estimation results.
Kiwata, Hirohito
Energy Technology Data Exchange (ETDEWEB)
An anhomomorphic logic A* is the set of all possible realities for a quantum system. Our main goal is to find the 'actual reality' {Phi}{sub a} element of A* for the system. Reality filters are employed to eliminate unwanted potential realities until only {phi}{sub a} remains. In this paper, we consider three reality filters that are constructed by means of quantum integrals. A quantum measure {mu} can generate or actualize a {Phi} element of A* if {mu}(A) is a quantum integral with respect to {phi} for a density function f over events A. In this sense, {mu} is an 'average' of the truth values of {phi} with weights given by f. We mainly discuss relations between these filters and their existence and uniqueness properties. For example, we show that a quadratic reality generated by a quantum measure is unique. In this case we obtain the unique actual quadratic reality.
Gudder, Stan, E-mail: firstname.lastname@example.com [Department of Mathematics, University of Denver, Denver, CO 80208 (United States)
An Implementation of Content Boosted Collaborative Filtering Algorithm
Directory of Open Access Journals (Sweden)
Full Text Available Collaborative filtering (CF systems have been proven to be very effective for personalized and accurate recommendations. These systems are based on the Recommendations of previous ratings byvarious users and products. Since the present database is very sparse, the missing values are considered first and based on that, a complete prediction dataset are made. In this paper, some standardcomputational techniques are applied within the framework of Content-boosted collaborative filtering with imputational rating data to evaluate and produce CF predictions. The Content-boosted collaborative filtering algorithm uses either naive Bayes or means imputation, depending on the sparsity of the original CF rating dataset. Results are presented and shown that this approach performs better than a traditional content-based predictor and collaborative filters.
Boddu Raja Sarath Kumar,
Traditional and Modern Morphometrics: Review
Directory of Open Access Journals (Sweden)
Full Text Available Morphometrics, a branch of morphology, is the study of the size and shape components of biological forms and their variation in the population. In biological and medical sciences, there is a long history of attempts to quantitatively express the diversity of the size and shape of biological forms. On the basis of historical developments in morphometry, we address several questions related to the shape of organs or organisms that are considered in biological and medical studies. In the field of morphometrics, multivariate statistical analysis is used to rigorously address such questions. Historically, these methods have involved the analysis of collections of distances or angles, but recent theoretical, computational, and other advances have shifted the focus of morphometric procedures to the Cartesian coordinates of anatomical points. In recent years, in biology and medicine, the traditional morphometric studies that aim to analyze shape variation have been replaced by modern morphometric studies. In the biological and medical sciences, morphometric methods are frequently preferred for examining the morphologic structures of organs or organisms with regard to diseases or environmental factors. These methods are also preferred for evaluating and classifying the variation of organs or organisms with respect to growth or allometry time dependently. Geometric morphometric methods are more valid than traditional morphometric methods in protecting more morphological information and in permitting analysis of this information.
Gökhan OCAKO?LU
Radiopasteurization of traditional herbal medicine
International Nuclear Information System (INIS)
Investigation on the effects of irradiation using pasteurization dose of 500 krad (5kGy) on microbes contaminating traditional herbal medicine, produced by 3 large manufacturers in Indonesia, was carried out. Storage effects on microbial count moisture content of traditional herbal medicine packed in microbe tight packages, were also observed. The results showed that initial bacterial counts varied between 10"4 and 10"8 per gram, and mould and yeast counts varied between 0 and 10"5 per gram. These numbers decreased as much as 2 to 5 log cycles after irradiation with 500 krad. After 6 month storage, bacterial counts of irradiated samples decreased as much as 0 to 10"3 per gram. Initial moisture content varied from 5 to 12% and after 6 month storage the moisture content of most samples increased as much as 0 to 5%. Irradiated samples were found to be mould free, and most of the surviving microbes consisted of spore forming aerobic bacteria and yeast. (author)
International Nuclear Information System (INIS)
After the TMI accident in the USA, the Swedish Government in 1981 decided that all Swedish nuclear power plants must be upgraded to mitigate the consequences of severe accidents. Mitigating measures were required to be in place by 1985 for the Barsebaeck plants and by 1988 for the remaining plants. The technical solution selected for accident mitigation was filtered venting of the reactor containment. The filtering requirement was that the release of radioactivity should be less than 0.1% of the core inventory. In Barsebaeck the filter consists of a gravel bed with a volume of 10,000 cubic metres. For the other Swedish plants (7 BWRs and 3 PWRs) a wet scrubber system of significantly smaller volume (300-400 cubic metres) has been selected. This filter system which is called FILTRA-MVSS (Multi Venturi Scrubber System) has been jointly developed by ASEA-ATOM and FLAEKT Industri, two companies belonging to the ASEA BROWN BOVERI Group of Companies. The FILTRA-MVSS which can accomodate a wide range of flow rates based on an automatic passive technique consists of a number of venturi nozzles submerged in a pool of water. The venturi separation technique has been employed in the field of industrial air pollution control for several decades. The technique has now been further developed and adapted for the cleaning of contaminated radioactive off-gases that might be the consequence of a severe reactor accident. After the Chernobyl accident the discussion on filtered containment venting intensified also in other European countries, and several countries, for example France, the Federal Republic of Germany and Finland are now planning for filtered venting systems. The FILTRA-MVSS system can be designed to meet a wide range of hypothetic design basis events for both BWR and PWR plants. The system can be optimized with respect to its size depending on various pressure requirements and it can be optimized for specified decontamination factors. (author). Poster presentation. 3 figs
The Dual Carrier ABSK System Based on a FIR Bandpass Filter
Directory of Open Access Journals (Sweden)
Full Text Available The special impacting filter (SIF with IIR structure has been used to demodulate ABSK signals. The key points of SIF, including the resonance circuit's high Q value and the "slope-phase discrimination" character of the filter sideband, are demonstrated in the paper. The FIR narrow-band bandpass filtering system, which can also provide the impact-filtering effect, is proposed. A dual carrier system of ABSK signals is designed with the proposed FIR filter as its receiver. The simulation results show that the FIR filter can work well. Moreover, compared to the traditional SIF, the proposed FIR filter can not only achieve higher spectral efficiency, but also give better demodulation performance.
Zhimin Chen
Shifted Linear Interpolation Filter
Directory of Open Access Journals (Sweden)
Full Text Available Linear interpolation has been adapted in many signal and image processing applications due to its simple implementation and low computational cost. In standard linear interpolation the kernel is the second order B-spline. In this work we show that the interpolation error can be remarkably diminished by using the time-shifted B-spline as an interpolation kernel. We verify by experimental tests that the optimal shift is. In VLSI and microprocessor circuits the shifted linear interpolation (SLI algorithm can be effectively implemented by the z-transform filter. The interpolation error of the SLI filter is comparable to the more elaborate higher order cubic convolution interpolation.
Hannu Olkkonen
Subwavelength grating filtering devices.
We propose and simulate the characteristics of optical filters based on subwavelength gratings. In particular, we demonstrate through numerical simulations the feasibility of implementing SWG Bragg gratings in silicon-on-insulator (SOI). We also propose SWG ring resonators in SOI and verify their operation using numerical simulations and experiments. The fabricated devices exhibit an extinction ratio as large as 30 dB and a Q-factor as high as ~20,000. These fundamental SWG filters can serve as building blocks for more complex devices. PMID:24977793
Wang, Junjia; Glesk, Ivan; Chen, Lawrence R
Directory of Open Access Journals (Sweden)
Full Text Available In this paper we present a switched capacitor filter design using the SC22324 1C, which is fitted with an E2PROM. It contains four digitally programmable switched-capacitor filter sections, in order to obtain different responses. The SC22324 also contains the on-chip RAM. We'd like to explain, how could the on-chip RAM controlled via a PC. In this way the chip may be used afterwards with a menu where the user may select the wanted parameters.
M. Van Looy
Continuously variable electrooptic filter
International Nuclear Information System (INIS)
A PLZT electrooptic filter is being used to control the intensity of light transmitted to a video camera from samples undergoing pulsed electron beam thermal testing. This electron beam test system is part of a materials development program for fusion energy applications. During the testing, sample surface temperatures may reach 30000C and the intense light from these pulses is potentiallly damaging to the camera. The use of a variable density electrooptic filter prevents this damage and provides improved image quality during rapid changes of surface temperature
Filters in topology optimization
DEFF Research Database (Denmark)
In this article, a modified (``filtered'') version of the minimum compliance topology optimization problem is studied. The direct dependence of the material properties on its pointwise density is replaced by a regularization of the density field using a convolution operator. In this setting it is possible to establish the existence of solutions. Moreover, convergence of an approximation by means of finite elements can be obtained. This is illustrated through some numerical experiments. The ``filtering'' technique is also shown to cope with two important numerical problems in topology optimization, \\emph{checkerboards} and \\emph{mesh dependent} designs.
Bourdin, Blaise
Digital filters in spectrometry
International Nuclear Information System (INIS)
In this work is presented the development and application of the digital signal processing for different multichannel analysis spectra. The use of the smoothing classic methods in applications of signal processing is illustrated by a filters discussion; autoregressive, mobile average and the ARMA filters. Generally, simple routines of lineal smoothing do not provide appropriate smoothing of the data that show the local ruggedness as the strong discontinuities; however the indicated development algorithms have been enough to leave adapting to this task. Four algorithms were proven: autoregressive, mobile average, ARMA and binomial methods for 5, 7, and 9 of data, everything in the domain of the time and programmed in Mat lab. (Author)
International Nuclear Information System (INIS)
In thermal power stations, both conventional and nuclear, the corrosion products (crud particles) are carried by water, steam or gas through the plant, contaminating everything including turbines and other machinery. A convenient way of applying magnetic filtration to industrial streams is to use particle collectors, fabricated from permanent magnets, that are appropriately positioned in cage units which in turn form a large scale filtration system. Hence, the invention and the name: Magnetic Cage Filter (MCF). In this paper, the design of MCFs is described and the theory of together with experimental results on the capture of fine particles of crud by these filters are presented
Survey of HEPA filter experience
International Nuclear Information System (INIS)
A survey of high efficiency particulate air (HEPA) filter applications and experience at Department of Energy (DOE) sites was conducted to provide an overview of the reasons and magnitude of HEPA filter changeouts and failures. Results indicated that approximately 58% of the filters surveyed were changed out in the three year study period, and some 18% of all filters were changed out more than once. Most changeouts (63%) were due to the existence of a high pressure drop across the filter, indicative of filter plugging. Other reasons for changeout included leak-test failure (15%), preventive maintenance service life limit (13%), suspected damage (5%) and radiation buildup (4%). Filter failures occurred with approximately 12% of all installed filters. Of these failures, most (64%) occurred for unknown or unreported reasons. Handling or installation damage accounted for an additional 19% of reported failures. Media ruptures, filter-frame failures and seal failures each accounted for approximately 5 to 6% of the reported failures
Nonlinear Filter Based Image Denoising Using AMF Approach
This paper proposes a new technique based on nonlinear Adaptive Median filter (AMF) for image restoration. Image denoising is a common procedure in digital image processing aiming at the removal of noise, which may corrupt an image during its acquisition or transmission, while retaining its quality. This procedure is traditionally performed in the spatial or frequency domain by filtering. The aim of image enhancement is to reconstruct the true image from the corrupted image. The process of image acquisition frequently leads to degradation and the quality of the digitized image becomes inferior to the original image. Filtering is a technique for enhancing the image. Linear filter is the filtering in which the value of an output pixel is a linear combination of neighborhood values, which can produce blur in the image. Thus a variety of smoothing techniques have been developed that are non linear. Median filter is the one of the most popular non-linear filter. When considering a small neighborhood it is highly e...
Thivakaran, T K
Advanced Microring Photonic Filter Design
This chapter reviews the development of high-order photonic filters based on coupled microring resonators for optical spectral engineering applications. Advanced microring filter architectures capable of realizing general infinite impulse response optical transfer functions with finite transmission zeros are presented. Techniques for the analysis and exact synthesis of these devices to achieve a prescribed filter response are also described in detail. Examples of advanced optical filter designs such as high-order pseudo-elliptic filters and filters with maximally flat group delay are given to illustrate the potential applications of these general microring architectures in optical spectral engineering.
van, Vien
The Promise of Traditional Medicines
Directory of Open Access Journals (Sweden)
Full Text Available The usage of plants, plant extracts or plant-derived pure chemicals to treat disease become a therapeutic modality, which has stood the test of time. Today several pharmacological classes of drugs include a natural product prototype. Aspirin, atropine, ephedrine, digoxin, morphine, quinine, reserpine and tubocurarine are a few examples of modern drugs, which were originally discovered through the study of traditional cures and folk knowledge of indigenous people. A team work amongst ethnobotanists, ethnopharmacologists, physicians and phytochemists is must for the fruitful outcome on medicinal plants research. While the ethnopharmacologists have a greater role in the rationalization of combination of activities, the phytochemist's role will slightly shift towards standardization of herbal medicines.
N.N. Inamdar
Digitally interpreting traditional folk crafts.
Preserving cultural heritage requires that objects persist throughout time and continue to communicate an intended meaning. Owing to the decreasing number of masters of folk crafts, fading technologies, and crafts losing economic ground, computer-based preservation and interpretation of such crafts is necessary. To fabricate and preserve traditional crafts, a long-term applied-research project has combined mathematics and software tools with compact, cheap, and environmentally friendly desktop fabrication tools, including 3D printers. Case studies involving the digital capture of Japanese lacquerware and Norwegian carvings illustrate the project's modeling approach and fabrication system. Besides modeling existing artifacts, the project includes Web presentations of the models, automated model fabrication, and experimental manufacturing of new designs and forms. PMID:24808155
Vilbrandt, T; Vilbrandt, C; Pasko, G I; Stamm, C; Pasko, A
Metamaterial Tunable Filter Design
Digital Repository Infrastructure Vision for European Research (DRIVER)
This paper presents a new concept to implement a tunable filter metamaterial with dual negative refraction composed of ferrite slabs and metallic resonators, including split-ring resonators (SRR), and short wire pairs. The ferrite slabs under an applied magnetics bias provide one magnetic resonance frequency band and the metallic resonators provide another one. The continuous wires within the metamaterials provide the negati...
Naima Benmostefa; Meliani, M.; Ouslimani, H.
High temperature filter materials
Energy Technology Data Exchange (ETDEWEB)
Objectives of this program are to identify the potential long-term thermal/chemical effects that advanced coal-based power generating system environments have on the stability of porous ceramic filter materials, as well as to assess the influence of these effects on filter operating performance and life. We have principally focused our efforts on developing an understanding of the stability of the alumina/mullite filter material at high temperature (i.e., 870, 980, and 1100{degrees}C) under oxidizing conditions which contain gas phase alkali species. Testing has typically been performed in two continuous flow-through, high temperature test facilities at the Westinghouse Science and Technology Center, using 7 cm diameter {times} 6.4 mm thick discs. (Alvin, 1992) Each disc of ceramic filter material is exposed for periods of 100 to 3,000 hours in duration. Additional efforts have been performed at Westinghouse to broaden our understanding of the stability of cordierite, cordierite-silicon nitride, reaction and sintered silicon nitride, and clay bonded silicon carbide under similar simulated advanced coal fired process conditions. The results of these efforts are presented in this paper.
Alvin, M.A.; Lippert, T.E.; Bachovchin, D.M. [Westinghouse Electric Corp., Pittsburgh, PA (United States). Science and Technology Center; Tressler, R.E. [Pennsylvania State Univ., University Park, PA (United States)
High temperature filter materials
Energy Technology Data Exchange (ETDEWEB)
Objectives of this program are to identify the potential long-term thermal/chemical effects that advanced coal-based power generating system environments have on the stability of porous ceramic filter materials, as well as to assess the influence of these effects on filter operating performance and life. We have principally focused our efforts on developing an understanding of the stability of the alumina/mullite filter material at high temperature (i.e., 870, 980, and 1100[degrees]C) under oxidizing conditions which contain gas phase alkali species. Testing has typically been performed in two continuous flow-through, high temperature test facilities at the Westinghouse Science and Technology Center, using 7 cm diameter [times] 6.4 mm thick discs. (Alvin, 1992) Each disc of ceramic filter material is exposed for periods of 100 to 3,000 hours in duration. Additional efforts have been performed at Westinghouse to broaden our understanding of the stability of cordierite, cordierite-silicon nitride, reaction and sintered silicon nitride, and clay bonded silicon carbide under similar simulated advanced coal fired process conditions. The results of these efforts are presented in this paper.
Alvin, M.A.; Lippert, T.E.; Bachovchin, D.M. (Westinghouse Electric Corp., Pittsburgh, PA (United States). Science and Technology Center); Tressler, R.E. (Pennsylvania State Univ., University Park, PA (United States))
Structural notch filter optimization
Energy Technology Data Exchange (ETDEWEB)
A modified algorithm for nonlinear constrained optimization of structural mode filters for an aeroelastic aircraft model is presented. The optimizer set-up and control is implemented in a MATLAB{trademark} graphical user interface environment. It is shown that the modified algorithm gives improved performance over existing nonlinear constrained optimization methods.
Felton, R.; Burge, S.; Bradshaw, A. [Lancaster Univ. (United Kingdom). Dept. of Engineering
An overview of the studies for the ATLAS Event Filter is given. The architecture and the high level design of the DAQ-1 prototype is presented. The current status if the prototypes is briefly given. Finally, future plans and milestones are given. (11 refs).
Beck, H P; Boissat, C; Davis, R; Duval, P Y; Etienne, F; Fede, E; Francis, D; Green, P; Hemmer, F; Jones, R; MacKinnon, J; Mapelli, Livio P; Meessen, C; Mommsen, R K; Mornacchi, Giuseppe; Nacasch, R; Negri, A; Pinfold, James L; Polesello, G; Qian, Z; Rafflin, C; Scannicchio, D A; Stanescu, C; Touchard, F; Vercesi, V
Digital Repository Infrastructure Vision for European Research (DRIVER)
The kalman Filter developed in the early sixties by R. E. Kalman is a recursive state estimator for partially observed non-stationary stochastic prosses. It gives an optimal estimate in the least squares sense of the actual value of state vector from noisy observations.
Andrade Cetto, Juan
Energy Technology Data Exchange (ETDEWEB)
Potential benefits of ceramic filters in nuclear facilities: (1) Short term benefit for DOE, NRC, and industry - (a) CalPoly HTTU provides unique testing capability to answer questions for DOE - High temperature testing of materials, components, filter, (b) Several DNFSB correspondences and presentations by DNFSB members have highlighted the need for HEPA filter R and D - DNFSB Recommendation 2009-2 highlighted a nuclear facility response to an evaluation basis earthquake followed by a fire (aka shake-n-bake) and CalPoly has capability for a shake-n-bake test; (2) Intermediate term benefit for DOE and industry - (a) Filtration for specialty applications, e.g., explosive applications at Nevada, (b) Spin-off technologies applicable to other commercial industries; and (3) Long term benefit for DOE, NRC, and industry - (a) Across industry, strong desire for better performance filter, (b) Engineering solution to safety problem will improve facility safety and decrease dependence on associated support systems, (c) Large potential life-cycle cost savings, and (d) Facilitates development and deployment of LLNL process innovations to allow continuous ventilation system operation during a fire.
Mitchell, M A; Bergman, W; Haslam, J; Brown, E P; Sawyer, S; Beaulieu, R; Althouse, P; Meike, A
Directory of Open Access Journals (Sweden)
Full Text Available A major security challenge on the Internet is the existence of the large number of compromised machines. Such machines have been increasingly used to launch various security attacks including spamming and spreading malware, DDoS, and identity theft. These compromised machines are called "Zombies". In general E-mail applications and providers uses spam filters to filter the spam messages. Spam filtering is a technique for discriminating the genuine message from the spam messages. The attackers send the spam messages to the targeted machine by exalting the filters, which causes the increase in false positives and false negatives. We develop an effective spam zombie detection system named SPOT by monitoring outgoing messages of a network. SPOT focuses on the number of outgoing messages that are originated or forwarded by each computer on a network to identify the presence of Zombies. SPOT is designed based on a powerful statistical tool called Sequential Probability Ratio Test, which has bounded false positive and false negative error rates.
Arathy Rajagopal
We propose using the extra dimension separating the domain walls carrying lattice quarks of opposite handedness to gradually filter out the ultraviolet fluctuations of the gauge fields that are felt by the fermionic excitations living in the bulk. This generalization of the homogeneous domain wall construction has some theoretical features that seem nontrivial.
Bär, O; Neuberger, H; Witzel, O; Baer, Oliver; Narayanan, Rajamani; Neuberger, Herbert; Witzel, Oliver
Like nature's honeycomb, foam is a structure of many-sided cells, apparently solid but actually only three percent material and 97 percent air. Foam is made by a heat-producing chemical reaction which expands a plastic material in a manner somewhat akin to the heat-induced rising of a loaf of bread. The resulting structure of interconnected cells is flexible yet strong and extremely versatile in applicati6n. Foam can, for example, be a sound absorber in one form, while in another it allows sound to pass through it. It can be a very soft powder puff material and at the same time a highly abrasive scrubber. A sampling of foam uses includes stereo speaker grilles, applying postage meter ink, filtering lawnmower carburetor air; deadening noise in trucks and tractors, applying cosmetics, releasing fabric softener and antistatic agents in home clothes dryers, painting, filtering factory heating and ventilating systems, shining shoes, polishing cars, sponge-mopping floors, acting as pre-operative surgical scrubbers-the list is virtually limitless. The process by which foam is made produces "windows," thin plastic membranes connecting the cell walls. Windowed foam is used in many applications but for certain others-filtering, for example-it is desirable to have a completely open network. Scott Paper Company's Foam Division, Chester, Pennsylvania, improved a patented method of "removing the windows," to create an open structure that affords special utility in filtering applications. NASA technology contributed to Scott's improvement.
Data may be overprinted by a steady-state cyclical noise (hum). Steady-state indicates that the noise is invariant with time; its attributes, frequency, amplitude, and phase, do not change with time. Hum recorded on seismic data usually is powerline noise and associated higher harmonics; leakage from full-waveform rectified cathodic protection devices that contain the odd higher harmonics of powerline frequencies; or vibrational noise from mechanical devices. The fundamental frequency of powerline hum may be removed during data acquisition with the use of notch filters. Unfortunately, notch filters do not discriminate signal and noise, attenuating both. They also distort adjacent frequencies by phase shifting. Finally, they attenuate only the fundamental mode of the powerline noise; higher harmonics and frequencies other than that of powerlines are not removed. Digital notch filters, applied during processing, have many of the same problems as analog filters applied in the field. The method described here removes hum of a particular frequency. Hum attributes are measured by discrete Fourier analysis, and the hum is canceled from the data by subtraction. Errors are slight and the result of the presence of (random) noise in the window or asynchrony of the hum and data sampling. Error is minimized by increasing window size or by resampling to a finer interval. Errors affect the degree of hum attenuation, not the signal. The residual is steady-state hum of the same frequency. ?? 1994.
Knapp, R. W.; Anderson, N. L.
Optimal L-filters for vector magnitude filtering
Digital Repository Infrastructure Vision for European Research (DRIVER)
Vector magnitude filtering on vectors represented in polar coordinates can be useful in cases where vector direction is either of no importance or must be preserved intact. This paper focuses on the design of optimal L-filters for the vector magnitude filtering of certain types of two-channel vector fields (rotational, translational and zooming motion vector fields) corrupted by additive noise. Expressions for the unconstrained, unbiased and location invariant L-filter coefficients are derive...
Nikolaidis, N.; Pitas, I.
Experimental study of filter cake formation on different filter media
International Nuclear Information System (INIS)
Removal of particulate matter from gases generated in the process industry is important for product recovery as well as emission control. Dynamics of filtration plant depend on operating conditions. The models, that predict filter plant behaviour, involve empirical resistance parameters which are usually derived from limited experimental data and are characteristics of the filter media and filter cake (dust deposited on filter medium). Filter cake characteristics are affected by the nature of filter media, process parameters and mode of filter regeneration. Removal of dust particles from air is studied in a pilot scale jet pulsed bag filter facility resembling closely to the industrial filters. Limestone dust and ambient air are used in this study with two widely different filter media. All important parameters like pressure drop, gas flow rate, dust settling, are recorded continuously at 1s interval. The data is processed for estimation of the resistance parameters. The pressure drop rise on test filter media is compared. Results reveal that the surface of filter media has an influence on pressure drop rise (concave pressure drop rise). Similar effect is produced by partially jet pulsed filter surface. Filter behaviour is also simulated using estimated parameters and a simplified model and compared with the experimental results. Distribution of cake area load is therefore an important aspect of jet pulse cleaned bag filter modeling. Mean specific cake resistance remains nearly constant on thoroughly jet pulse cleaned membrane coated filter bags. However, the trend can not be confirmed without independent cake height and density measurements. Thus the results reveal the importance of independent measurements of cake resistance. (author)
Design of Wideband Microstrip Filters with Non-Equiripple Responses and Low Sensitivity
This paper presents a novel design procedure for wideband microstrip bandpass filters with non-equiripple filtering frequency responses and low sensitivity. Different from the traditional Chebyshev transfer function filters, the return loss zeros of the proposed non-equiripple filters can be redistributed within the operating passband. For the industrial applications, the proposed filters have a reduced sensitivity to manufacturing errors and exhibit good tolerance control for both specified bandwidth and maximum in-band reflection loss. By deriving the transfer functions, a synthesis approach with a set of non-linear equations can be established according to the specifications such as the bandwidth and predetermined reflection lobes. Without performing any post optimization in the full-wave simulation, the non-equiripple synthesized results have less sensitivity and fractional bandwidth (delta) error in comparison with those obtained from traditional Chebyshev transfer functions with equiripple frequency res...
Gao, S S
Generalized Selection Weighted Vector Filters
Directory of Open Access Journals (Sweden)
Full Text Available This paper introduces a class of nonlinear multichannel filters capable of removing impulsive noise in color images. The here-proposed generalized selection weighted vector filter class constitutes a powerful filtering framework for multichannel signal processing. Previously defined multichannel filters such as vector median filter, basic vector directional filter, directional-distance filter, weighted vector median filters, and weighted vector directional filters are treated from a global viewpoint using the proposed framework. Robust order-statistic concepts and increased degree of freedom in filter design make the proposed method attractive for a variety of applications. Introduced multichannel sigmoidal adaptation of the filter parameters and its modifications allow to accommodate the filter parameters to varying signal and noise statistics. Simulation studies reported in this paper indicate that the proposed filter class is computationally attractive, yields excellent performance, and is able to preserve fine details and color information while efficiently suppressing impulsive noise. This paper is an extended version of the paper by Lukac et al. presented at the 2003 IEEE-EURASIP Workshop on Nonlinear Signal and Image Processing (NSIP '03 in Grado, Italy.
Smolka Bogdan
Traditional perception of Greeks in Serbian oral tradition
Directory of Open Access Journals (Sweden)
Full Text Available Based on material on Greeks from Vuk's corpus of epic poems, we discuss the construction of ethnic stereotype of Greeks in Serbian language. However, the limitation of the paper's possible conclusion lies in the nature of the corpus: Vuk had deliberately chosen one material over another, therefore, the corpus relating to Greeks cannot be considered as representative of the whole Serbian folk poems. Therefore, the discussion is limited to certain elements of the stereotype. Nevertheless, these Serbian epic folk poems contain many layers: historical, geographical, sociological, mythological and so on, with a strong foundation in traditional culture; thus, they provide an insight into geo-political situation of the time period, viewpoints, perspectives and experiences of other ethnic groups that Serbs have been into contact with. In particular, the relationship toward Greeks was marked with pronounced patriarchal attitude concerning others: we-others, ours-foreign, good-bad. In this sense, Greeks are portrayed as foreign, and as such, as a potential source of danger. On the other hand, Greeks are Christian Orthodox, which associates them with the category ours. In socio-economic sense, they were traders and wealthy, respected gentlemen. In epical-heroic profile, they were not considered as great heroes, but as "lousy army", and frequently, as unfaithful.
Konjik Ivana
Low-power implementation of polyphase filters in Quadratic Residue Number System
DEFF Research Database (Denmark)
The aim of this work is the reduction of the power dissipated in digital filters, while maintaining the timing unchanged. A polyphase filter bank in the Quadratic Residue Number System (QRNS) has been implemented and then compared, in terms of performance, area, and power dissipation to the implementation of a polyphase filter bank in the traditional two's complement system (TCS). The resulting implementations, designed to have the same clock rates, show that the QRNS filter is smaller and consumes less power than the TCS one.
Cardarilli, Gian Carlo; Re, Andrea Del
Fast algorithm of the robust Gaussian regression filter for areal surface analysis
International Nuclear Information System (INIS)
In this paper, the general model of the Gaussian regression filter for areal surface analysis is explored. The intrinsic relationships between the linear Gaussian filter and the robust filter are addressed. A general mathematical solution for this model is presented. Based on this technique, a fast algorithm is created. Both simulated and practical engineering data (stochastic and structured) have been used in the testing of the fast algorithm. Results show that with the same accuracy, the processing time of the second-order nonlinear regression filters for a dataset of 1024*1024 points has been reduced to several seconds from the several hours of traditional algorithms
Improvement in design of hi-lo impedanse microstrip low-pass filter
Digital Repository Infrastructure Vision for European Research (DRIVER)
A microstrip low-pass filter with the sharp rejection and wide stop band is presented. The circuit model is developed and analyzed based on traditional hi-lo impedance technique. Achieving the attenuation pole in vicinity of the desired -3dB point, magnetic coupling is added. For improving the design and miniaturization of the circuit, capacitance associated with shunt arm of the 3rd order low pass filter is explored. Comparison of proposed low pass filter has been done with existing filters ...
Jha, K. R.; Rai, M.
Toward Green Cloud Computing: An Attribute Clustering Based Collaborative Filtering Method for Virtual Machine Migration
Directory of Open Access Journals (Sweden)
Full Text Available In this study, an attribute clustering based collaborative filtering algorithm is depicted for virtual machine migration towards green Cloud computing. The algorithm utilizes similarity characteristics of virtual machine task related attributes, especially CPU related attributes, to filter redundant data by feature selection. Then by referencing K-Means clustering to effectively solve the rating scale problems existing in the traditional collaborative filtering recommendation algorithm. Experiments use virtual machine task related information for clustering the data. By integration of a scaled rating scheme on task related properties and the collaborative filtering philosophy to provide migration recommendation for system administrators.
Zhang Liu-Mei
Research of Collaborative Filtering Recommendation Algorithm based on Network Structure
Directory of Open Access Journals (Sweden)
Full Text Available This paper combines the classic collaborative filtering algorithm with personalized recommendation algorithm based on network structure. For the data sparsity and malicious behavior problems of traditional collaborative filtering algorithm, the paper introduces a new kind of social network-based collaborative filtering algorithm. In order to improve the accuracy of the personalized recommendation technology, we first define empty state in the state space of multi-dimensional semi-Markov processes and obtain extended multi-dimensional semi-Markov processes which are combined with social network analysis theory, and then we get social network information flow model. The model describes the flow of information between the members of the social network. So, we propose collaborative filtering algorithm based on social network information flow model. The algorithm uses social network information and combines user trust with user interest and find nearest neighbors of the target user and then forms a project recommended to improve the accuracy of recommended. Compared with the traditional collaborative filtering algorithm, the algorithm can effectively alleviate the sparsity and malicious behavior problem, and significantly improve the quality of the recommendation system recommended.
Hui PENG
Lead Encephalopathy Due to Traditional Medicines
Digital Repository Infrastructure Vision for European Research (DRIVER)
Traditional medicine use is common in developing countries and increasingly popular in the western world. Despite the popularity of traditional medicines, scientific research on safety and efficacy is limited. However documented fatalities and severe illness due to lead poisoning are increasingly recognized to be associated with traditional medicine use. As society becomes more globalized, it is imperative for pharmacists and health care providers to learn about the safety of traditional medi...
Karri, Surya K.; Saper, Robert B.; Kales, Stefanos N.
Why Breast Cancer Patients Seek Traditional Healers
Digital Repository Infrastructure Vision for European Research (DRIVER)
Traditional healing is a common practice in low and middle income countries such as Malaysia. Eighty percent of Malaysians consult traditional healers or "bomoh" at some time in their life for health-related issues. The purpose of our study was to explore why breast cancer patients visit traditional healers. This is a qualitative study utilizing in-depth interviews with 11 cancer survivors who sought both traditional and Western medicine. The findings revealed the following reasons for wh...
Muhamad, Mazanah; Merriam, Sharan; Suhami, Norhasmilia
Directory of Open Access Journals (Sweden)
Full Text Available The notion of fated filters in R0-algebras is introduced. Characterizations of (fated filters are given. A filter generated by a set is established. By introducing the notion of finite ⊙-property, we show that if F is a nonempty subset of an R0-algebra L that has the finite ⊙-property, then there exists a maximal filter of L containing F.
Liu Lianzhen
Text Classification for Web Filtering
Digital Repository Infrastructure Vision for European Research (DRIVER)
This talk deals with the application of text classification techniques to Web filtering, with particular emphasis on filtering unsuitable content such as pornographic or violent content. The talk introduces text classification, its tools, techniques, and applications, and then discusses how filtering unsuitable Web content can be seen as the intersection of three different applications: Web page classification, filtering, and detection unsuitable content. The characteristics of these three ap...
Scientific Electronic Library Online (English)
Full Text Available SciELO Brazil | Language: English Abstract in portuguese A preocupaçăo com o câncer de pele hoje em dia vem crescendo cada vez mais principalmente em países tropicais, onde a incidęncia da radiaçăo UVA/B é maior. O uso correto de protetores solares é a forma mais eficaz de prevenir o aparecimento desta doença. Os ativos utilizados em protetores solares po [...] dem ser filtros orgânicos e inorgânicos. Filtros inorgânicos apresentam muitas vantagens em relaçăo aos orgânicos, tais como fotoestabilidade, ausęncia de irritabilidade e amplo espectro de proteçăo. Entretanto, em razăo de apresentarem alto índice de refraçăo, os ativos inorgânicos conferem aos protetores solares aparęncia esbranquiçada, diminuindo sua atratividade estética. Muitas alternativas tęm sido desenvolvidas no sentido de resolver este problema e dentre elas pode-se destacar o uso da nanotecnologia. Estima-se que o uso de nanomateriais deve crescer das atuais 2000 para 58000 toneladas até 2020. Neste sentido, este trabalho tem como objetivo fazer a análise crítica abordando diferentes aspectos envolvidos tanto na obtençăo de protetores solares inorgânicos (rotas de sínteses propostas nos últimos anos) quanto na permeabilidade, na segurança e em outros aspectos relacionados ŕ nova geraçăo de filtros solares inorgânicos. Abstract in english Nowadays, concern over skin cancer has been growing more and more, especially in tropical countries where the incidence of UVA/B radiation is higher. The correct use of sunscreen is the most efficient way to prevent the development of this disease. The ingredients of sunscreen can be organic and/or [...] inorganic sun filters. Inorganic filters present some advantages over organic filters, such as photostability, non-irritability and broad spectrum protection. Nevertheless, inorganic filters have a whitening effect in sunscreen formulations owing to the high refractive index, decreasing their esthetic appeal. Many techniques have been developed to overcome this problem and among them, the use of nanotechnology stands out. The estimated amount of nanomaterial in use must increase from 2000 tons in 2004 to a projected 58000 tons in 2020. In this context, this article aims to analyze critically both the different features of the production of inorganic filters (synthesis routes proposed in recent years) and the permeability, the safety and other characteristics of the new generation of inorganic filters.
Manaia, Eloísa Berbel; Kaminski, Renata Cristina Kiatkoski; Corręa, Marcos Antonio; Chiavacci, Leila Aparecida.
This report summarizes the results obtained during the contract No. F 19628-88-K-0018 entitled 'Optimal Phase-only Filters'. This research was focused on Phase-only Filters (POFs) and Binary Phase-only Filters (BPOFs). We prove in this report that the con...
B. V. Kumar Z. Bahri
Research on E-mail Filtering Based On Improved Bayesian
Digital Repository Infrastructure Vision for European Research (DRIVER)
Naive Bayesian has been widely used in spam filter because it simply and it also could classify texts more correctly and quickly. However, in the process of classifying and filtering, the traditional method doesn't consider the different features between the spam mail and the legitimat...
Pei-yu Liu; Li-wei Zhang; Zhen-fang Zhu
Direct analysis of air filter samples for alpha emitting isotopes
International Nuclear Information System (INIS)
The traditional method for determination of alpha emitting isotopes on air filters has been to process the samples by radiochemical methods. However, this method is too slow for cases of incidents involving radioactive materials where the determination of personnel received dose is urgent. A method is developed to directly analyze the air filters taken from personal and area air monitors. The site knowledge is used in combination with alpha spectral information to identify isotopes. A mathematical function is developed to estimate the activity for each isotope. The strengths and weaknesses of the method are discussed
Direct analysis of air filter samples for alpha emitting isotopes
Energy Technology Data Exchange (ETDEWEB)
The traditional method for determination of alpha emitting isotopes on air filters has been to process the samples by radiochemical methods. However, this method is too slow for cases of incidents involving radioactive materials where the determination of personnel received dose is urgent. A method is developed to directly analyze the air filters taken from personal and area air monitors. The site knowledge is used in combination with alpha spectral information to identify isotopes. A mathematical function is developed to estimate the activity for each isotope. The strengths and weaknesses of the method are discussed.
Mohagheghi, A.H.; Ghanbari, F.; Ebara, S.B.; Enghauser, M.E. [Sandia National Labs., Albuquerque, NM (United States); Bakhtiar, S.N. [Westinghouse WIPP, Carlsbad, NM (United States)
Kazakh Traditional Dance Gesture Recognition
Full body gesture recognition is an important and interdisciplinary research field which is widely used in many application spheres including dance gesture recognition. The rapid growth of technology in recent years brought a lot of contribution in this domain. However it is still challenging task. In this paper we implement Kazakh traditional dance gesture recognition. We use Microsoft Kinect camera to obtain human skeleton and depth information. Then we apply tree-structured Bayesian network and Expectation Maximization algorithm with K-means clustering to calculate conditional linear Gaussians for classifying poses. And finally we use Hidden Markov Model to detect dance gestures. Our main contribution is that we extend Kinect skeleton by adding headwear as a new skeleton joint which is calculated from depth image. This novelty allows us to significantly improve the accuracy of head gesture recognition of a dancer which in turn plays considerable role in whole body gesture recognition. Experimental results show the efficiency of the proposed method and that its performance is comparable to the state-of-the-art system performances.
Nussipbekov, A. K.; Amirgaliyev, E. N.; Hahn, Minsoo
History confirms the traditional meaning
Energy Technology Data Exchange (ETDEWEB)
This article complements the Rhinelander and Rubin article (this issue) and provides an account of US and USSR practice subsequent to the ABM Treaty. The Soviet subsequent practice from 1972 to date, like that of the US from 1972 until 1985, has fully supported the validity of the traditional interpretation, and explicitly rejected the reinterpretation, both before and after the reinterpretation was announced. The record is unambiguous. The Reagan administration's continued support of its radical reinterpretation of the ABM Treaty cannot be justified. In seeking to place the matter in perspective, one could do worse than apply the golden rule: what would the US have thought if after many years the USSR had suddenly, unilaterally, reinterpreted the ABM Treaty (or any other) to suit a policy purpose of its own, contrary to US policy and to the original clear understanding of both parties. What would the US have thought if the Soviets had then publicly acknowledged that they had done so without examining either their own ratification record of the record of the subsequent practice of the parties, without consulting any but one of their own negotiators, and before compiling much of their own relevant negotiating records.
Garthoff, R.L.
Controlling flow conditions of test filters in iodine filters
International Nuclear Information System (INIS)
Several different iodine filter and test filter designs and experience gained from their operation are presented. For the flow experiments, an iodine filter system equipped with flow regulating and measuring devices was built. In the experiments the influence of the packing method of the iodine sorption material and the influence of the flow regulating and measuring divices upon the flow conditions in the test filters was studied. On the basis of the experiments it has been shown that the flows through the test filters always can be adjusted to a correct value if there only is a high enough pressure difference available across the test filter ducting. As a result of the research, several different methods are presented with which the flows through the test filters in both operating and future iodine sorption system can easily be measured and adjusted to their correct values. (author)
Metamaterial Tunable Filter Design
Directory of Open Access Journals (Sweden)
Full Text Available This paper presents a new concept to implement a tunable filter metamaterial with dual negative refraction composed of ferrite slabs and metallic resonators, including split-ring resonators (SRR, and short wire pairs. The ferrite slabs under an applied magnetics bias provide one magnetic resonance frequency band and the metallic resonators provide another one. The continuous wires within the metamaterials provide the negative permittivity in a wide frequency band covering the two magnetic resonance bands. This type of metamaterialis analyzed in detail, and tunable stop band filters are successfully designed. The effective electromagnetic parameters obtained from the simulation of the S-parameters indicate that metamaterial exhibit negative refraction bands, which can be shifted by changing the magnetic bias.
Naima Benmostefa
Privacy Preserving Spam Filtering
We present an approach to training a binary logistic regression classifier in the setting where the training data needs to be kept private. We provide a theoretical analysis of the security of this procedure and experimental results for the problem of large scale spam detection. High performance spam filters often use character n-grams as features which result in large sparse vectors to which applying our protocol directly is not feasible. We explore various dimensionality reduction and parallelization approaches and provide a detailed analysis of the speed and accuracy trade-off. Our results show that we can achieve the accuracy of state of the art spam filters at comparable training and testing time of non-private version of logistic regression.
Pathak, Manas A; Raj, Bhiksha
Stochastic stacking without filters
International Nuclear Information System (INIS)
The rate of accumulation of antiprotons is a critical factor in the design of p anti p colliders. A design of a system to accumulate higher anti p fluxes is presented here which is an alternative to the schemes used at the CERN AA and in the Fermilab Tevatron I design. Contrary to these stacking schemes, which use a system of notch filters to protect the dense core of antiprotons from the high power of the stack tail stochastic cooling, an eddy current shutter is used to protect the core in the region of the stack tail cooling kicker. Without filters one can have larger cooling bandwidths, better mixing for stochastic cooling, and easier operational criteria for the power amplifiers. In the case considered here a flux of 1.4 x 10_8 per sec is achieved with a 4 to 8 GHz bandwidth
Digital Repository Infrastructure Vision for European Research (DRIVER)
While the most accurate solution to off-line structure from motion (SFM) problems is undoubtedly to extract as much correspondence information as possible and perform batch optimisation, sequential methods suitable for live video streams must approximate this to fit within fixed computational bounds. Two quite different approaches to real-time SFM - also called visual SLAM (simultaneous localisation and mapping) - have proven successful, but they sparsify the problem in different ways. Filter...
Strasdat, Hauke; Montiel, J. M. M.; Davison, Andrew J.
Energy Technology Data Exchange (ETDEWEB)
The current state of the problem of the combustion of homogeneous gas mixtures in a nondeformable inert porous medium is reviewed. In particular, attention is given to the history of the problem, stationary and nonstationary combustion regimes, velocity and structural characteristics of heat waves, mechanisms of their propagation, and near-critical and critical phenomena. The specific characteristics of this type of combustion and its relation to other filtering processes are discussed. 58 references.
Babkin, V.S.; Laevskii, IU.M.
Applied Filtered Density Function
Digital Repository Infrastructure Vision for European Research (DRIVER)
An overview is presented of recent advances in the filtered density function (FDF) modeling and simulation of turbulent combustion. The review is focused on the developments that have facilitated the FDF to be broadly applied in large eddy simulation (LES) of practical flows. These are primarily the development of a new Lagrangian Monte Carlo solver for the FDF, and the implementation of this solver on Eulerian domains portrayed by unstructured grids. With these developmen...
Levent Yilmaz, S.; Ansari, N.; Pisciuneri, P. H.; Nik, M. B.; Otis, C. C.; Givi, P.
In this two-minute radio program, a marine biology professor points out a number of the ecological functions that coastal mangrove forests perform. For example, he explains that mangrove forests serve as filters and nursery areas for fish. He contends that there are ecological and economic reasons to conserve mangroves. The archived program, part of the Pulse of the Planet radio show, is available here in text and audio formats. Copyright 2005 Eisenhower National Clearinghouse
Planet, Pulse O.
International Nuclear Information System (INIS)
Results of a preliminary investigation of a superconducting notch filter for possible application in the 2 to 30 MHz high frequency (HF) communication band are presented. The circuit was successfully implemented using planar geometry so that closed cycle refrigeration could be used to cool circuits fabricated from high T/sub c/ Nb_3Sn or Nb_3Ge thin films. In the present design, circuit Q's of about 2 x 10"3 were obtained with 50-ohm source and output impedance
Archimedes Mass Filter Vaporizer
Archimedes Technology Group, Inc., is developing a plasma mass separator called the Archimedes Filter that separates waste oxide mixtures ion by ion into two mass groups: light and heavy. Since high-level waste at Hanford has 99.9its radioactivity associated with heavy elements, the Archimedes Filter can effectively decontaminate over three-quarters of that waste. The Filter process involves some preprocessing followed by volatilization and separation by the magnetic and electric fields of the main plasma. This presentation describes the approach to volatilization of the waste oxy-hydroxide mixture by means of a very high heat flux (q > 10 MW/m2). Such a high heat flux is required to ensure congruent evaporation of the complex oxy-hydroxide mixture and is achieved by injection of small droplets of molten waste into an inductively coupled plasma (ICP) torch. This presentation further addresses different issues related to evaporation of the waste including modeling of droplet evaporation, estimates of parameters of plasma torch, and 2D modeling of the plasma. The experimental test bed for oxide vaporization and results of the initial experiments on oxide evaporation in 60 kW ICP torch will also be described.
Putvinski, S.; Agnew, A. F.; Cluggish, B. P.; Ohkawa, T.; Sevier, L.; Umstadter, K. R.; Dresvin, S. V.; Kuteev, B. V.; Feygenson, O. N.; Ivanov, D. V.; Zverev, S. G.; Miroshnikov, I. V.; Egorov, S. M.; Kiesewetter, D. V.; Maliugin, V. I.
Wiener-like correlation filters.
We introduce a new, to our knowledge, design for a Wiener-like correlation filter, which consists of cascading a phase-only filter (POF) with a photorefractive Wiener-like filter. Its performance is compared with that of the POF and the Wiener correlation filter (WCF). Correlation results show that for intermediate and higher levels of noise this correlation filter has a peak-to-noise ratio that is larger than that of either the POF or the WCF while still preserving a correlation peak that is almost as high as that of the POF. PMID:18337890
Khoury, J; Gianino, P D; Woods, C L
Application of a west Eurasian-specific filter for quasi-median network analysis: Sharpening the blade for mtDNA error detection
Digital Repository Infrastructure Vision for European Research (DRIVER)
The application of quasi-median networks provides an effective tool to check the quality of mtDNA data. Filtering of highly recurrent mutations prior to network analysis is required to simplify the data set and reduce the complexity of the network. The phylogenetic background determines those mutations that need to be filtered. While the traditional EMPOPspeedy filter was based on the worldwide mtDNA phylogeny, haplogroup-specific filters can more effectively highlight potential errors in dat...
International Nuclear Information System (INIS)
The analysis of data from CLAS is a multi-step process. After the detectors for a given running period have been calibrated, the data is processed in the so called pass-1 cooking. During the pass-1 cooking each event is reconstructed by the program a1c which finds particle tracks and computes momenta from the raw data. The results are then passed on to several data monitoring and filtering utilities. In CLAS software, a filter is a parameterless function which returns an integer indicating whether an event should be kept by that filter or not. There is a main filter program called g1-filter which controls several specific filters and outputs several files, one for each filter. These files may then be analyzed separately, allowing individuals interested in one reaction channel to work from smaller files than using the whole data set would require. There are several constraints on what the filter functions should do. Obviously, the filtered files should be as small as possible, however the filter should also not reject any events that might be used in the later analysis for which the filter was intended
Filter element in analysis apparatus
International Nuclear Information System (INIS)
This invention is concerned with the continuous-flow analysis of liquids, and more particularly, with the separation of mixtures of solid and liquid phases. The separator is comprised of a first conduit through which the mixture is passed and a lateral second conduit joined to the first conduit via a filter. Liquid is pumped from the first conduit through the filter into the second conduit, solid phase being retained by the filter. Means for backwashing the filter is provided. In continuous-flow analysis, the mixture in the first conduit is segmented by air or air and wash liquid, and the backflow washing is controlled to occur when an air or wash flow segment in the first conduit is in contact with the filter. The filter may be of sintered glass particles. The liquid phase is directed on to the filter via a special protuberance to facilitate and accelerate separation. (author)
Energy Technology Data Exchange (ETDEWEB)
This report contains the observations, test results, and conclusions of three separate in-service tests beginning in November 1979 and concluding in September 1983. The in-service tests described in this report produced encouraging results on filters constructed with fiberglass medium containing 5% Nomex and separators of aluminum foil coated with a thin film of vinyl-epoxy polymer. Filters containing medium with Kevlar fiber additives demonstrated they merited further evaluation. Other types of filters tested include separatorless filters (Flanders SuperFlow) and one filter with fiberglass separators. Asbestos-containing filters were used for comparison until their supply was exhausted. All filters tested were judged to have performed satisfactorily under the test conditions.
Terada, K.; Woodard, R.W.; Jensen, R.T.
Self-Tuning Synthesis Filter against Mutual Coupling and Interferences for GNSS and Its Implementation on Embedded Board
Digital Repository Infrastructure Vision for European Research (DRIVER)
Traditional spatial-temporal adaptive signal processing techniques are often applied to conduct narrowband and wideband interferences. However, its mitigation performance degrades greatly due to mutual coupling. To solve this problem, this paper aims to utilize a spatial-temporal self-tuning synthesis filter capable of mutual coupling compensation and interference mitigation. The spatial filter and temporal filter are to compensate for the effect of mutual coupling and interference mitigation...
Self-Tuning Synthesis Filter against Mutual Coupling and Interferences for GNSS and Its Implementation on Embedded Board
Digital Repository Infrastructure Vision for European Research (DRIVER)
Abstract Traditional spatial-temporal adaptive signal processing techniques are often applied to conduct narrowband and wideband interferences. However, its mitigation performance degrades greatly due to mutual coupling. To solve this problem, this paper aims to utilize a spatial-temporal self-tuning synthesis filter capable of mutual coupling compensation and interference mitigation. The spatial filter and temporal filter are to compensate for the effect of mutual coupling and inte...
Traditional Music in the Gambia : the role of traditional musicians in a society of change
Digital Repository Infrastructure Vision for European Research (DRIVER)
The aim of this research is to find out more about traditional music in Gambian society, to get a wider view of the tradition and what is happening to traditional music in a modern society. Furthermore, I want to find out if the informers consider that the traditional music is fading away from the society and if, in that case, any actions are being taken to preserve the tradition. The research question is: How do the traditional masters in the Gambia consider the role of traditional musicians...
O?ryd, Helena
Niobium filter on patient exposure and image quality
International Nuclear Information System (INIS)
The estimated annual dose to the population due to radiological examinations has reached by now the same level of the natural background. In order to reduce the probability of stochastic effects, it's necessary to minimize the medical exposure doses. In addition to the traditional techniques employed for dose reduction (intensifying screens, post-elaboration programs, beam filtration...), a niobium filter has been recently introduced with the property of having an X ray absorption peak between 19 and 30 keV, thus eliminating the portion of the spectrum that doesn't contribute to the radiological image but increases the patient dose. In this report, some of the image quality characteriztics are analyzed in order to compare the images obtained with and without filter in usual traditional radiology. (author)
Directory of Open Access Journals (Sweden)
Full Text Available In image processing, denoising is one of the important tasks. Despite the significant research conducted on this topic, the development of efficient denoising methods is still a compelling challenge. In this paper, comparison of Spatial Filters methods with the Homomorphic Filters Methods. The spatial filter methods like Median Filter and Wiener Filter are based on the simple formulas that are proposed by different authors. In Homomorphic Filters Method NormalShrink and BayesShrink are used. The basic idea of homomorphic methods is to denoise the image by applying wavelet transform to the noisy image, then thresholding the detailed wavelet coefficient and inverse transforming the set of thresholded coefficient to obtain the denoised image. In this soft thresholding technique is applied.
Abhinash Singla
Strain contouring with Gabor filters: filter bank design
A novel fringe processing method is proposed to segment whole-field strain distributions from interferometric deformation patterns by use of Gabor filters. This novel strategy is specifically proposed for strain measurement with a Gabor filter used as a set of wavelets. To increase computational speed as well as for selection of contour intervals, judicious design of the filter bank, based on the fringe pattern and the requirements of the user, is crucial in this methodology. A filter design strategy is developed and, based on the proposed filter design scheme, properly designed filter banks are generated and applied for strain contouring in low-strain and strain concentration regions. This scheme allows one to measure engineering strains within regions of interest and hence provides the design engineer great flexibility of monitoring, testing, or analysis.
Jun, Wang; Asundi, Anand
Choosing and using astronomical filters
As a casual read through any of the major amateur astronomical magazines will demonstrate, there are filters available for all aspects of optical astronomy. This book provides a ready resource on the use of the following filters, among others, for observational astronomy or for imaging: Light pollution filters Planetary filters Solar filters Neutral density filters for Moon observation Deep-sky filters, for such objects as galaxies, nebulae, and more Deep-sky objects can be imaged in much greater detail than was possible many years ago. Amateur astronomers can take photographs that rival those of professional observatories! The ability to do this has been brought about by the revolution in CCD cameras and improved filters. The book pinpoints which astronomical objects are best observed with which filters. Post-processing (using Photoshop) is also discussed, since it is helpful in further improving filtered astro images. The last part of the book is an observational guide to 100 deep sky objects that benefit f...
Griffiths, Martin
Energy Technology Data Exchange (ETDEWEB)
Types of filters are discussed developed by the Hydrogeology and Mine Draining Department of the POLTEGOR Research and Development Center for Surface Mining in Wroclaw. The Poltegor segment filter, used in the Belchatow brown coal surface mine, consists of plastic rings and a filter screen. It is characterized by good mechanical properties, good hydraulic properties, high corrosion resistance, uncomplicated repair and regeneration. An insert filter developed by POLTEGOR is an alternative to imported filters. It consists of a perforated tube and a set of inserted filter screens. This type of filter, successfully tested in Belchatow, is characterized by extremely high resistance to stresses and strains. A screen filter developed by POLTEGOR consists of a perforated tube and a screen made of tinplate. The filter, used in Belchatow, is also characterized by good hydraulic properties and high resistance to deformation. Filters made of granulated plastics with or without a carcass (used in Belchatow, Lubstow and Wladyslawow) are characterized by low specific weight, high porosity, high compression strength, high resistance to clogging, and high resistance to corrosion.
Energy Technology Data Exchange (ETDEWEB)
In this very brief, informal presentation, a representative of the US Nuclear Regulatory Commission outlines some problems with charcoal filter testing procedures and actions being taken to correct the problems. Two primary concerns are addressed: (1) the process to find the test method is confusing, and (2) the requirements of the reference test procedures result in condensation on the charcoal and causes the test to fail. To address these problems, emergency technical specifications were processed for three nuclear plants. A generic or an administrative letter is proposed as a more permanent solution. 1 fig.
Lyons, J. [Nuclear Regulatory Commission, Washington, DC (United States)
International Nuclear Information System (INIS)
The new approach to solving of the finding problem is proposed. The method is based on Discrete Projective Transformations (DPT), the List Square Fitting (LSF) and uses the information feedback in tracing for linear or quadratic track segments (TS). The fast and stable with respect to measurement errors and background points recurrent algorithm is suggested. The algorithm realizes the family of digital adaptive projective filters (APF) with known nonlinear weight functions-projective invariants. APF can be used in adequate control systems for collection, processing and compression of data, including tracking problems for the wide class of detectors. 10 refs.; 9 figs
DEFF Research Database (Denmark)
Using a Parzen density estimator any distribution can be approximated arbitrarily close by a sum of kernels. In particle filtering this fact is utilized to estimate a probability density function with Dirac delta kernels; when the distribution is discretized it becomes possible to solve an otherwise intractable integral. In this work we propose to extend the idea and use any kernel to approximate the distribution. The extra work involved in propagating small kernels through the nonlinear function can be made up for by decreasing the number of kernels needed, especially for high dimensional problems. A further advantage of using kernels with nonzero width is that the density estimate becomes continuous.
Lehn-Schiøler, Tue
Applied Filtered Density Function
Directory of Open Access Journals (Sweden)
Full Text Available An overview is presented of recent advances in the filtered density function (FDF modeling and simulation of turbulent combustion. The review is focused on the developments that have facilitated the FDF to be broadly applied in large eddy simulation (LES of practical flows. These are primarily the development of a new Lagrangian Monte Carlo solver for the FDF, and the implementation of this solver on Eulerian domains portrayed by unstructured grids. With these developments, it is now much easier to apply FDF for predictions of reacting flows in complex geometrical configurations.
S.Levent Yilmaz
Improving Recommendation Quality by Merging Collaborative Filtering and Social Relationships
Digital Repository Infrastructure Vision for European Research (DRIVER)
Matrix Factorization techniques have been successfully applied to raise the quality of suggestions generated by Collaborative Filtering Systems (CFSs). Traditional CFSs based on Matrix Factorization operate on the ratings provided by users and have been recently extended to incorporate demographic aspects such as age and gender. In this paper we propose to merge CFS based on Matrix Factorization and information regarding social friendships in order to provide users with more...
Meo, Pasquale; Ferrara, Emilio; Fiumara, Giacomo; Provetti, Alessandro
Kalman Filter Based Tracking in an Video Surveillance System
Digital Repository Infrastructure Vision for European Research (DRIVER)
In this paper we have developed a Matlab/Simulink based model for monitoring a contact in a video surveillance sequence. For the segmentation process and corect identification of a contact in a surveillance video, we have used the Horn-Schunk optical flow algorithm. The position and the behavior of the correctly detected contact were monitored with the help of the traditional Kalman filter. After that we have compared the results obtained from the optical flow method with the ones obtaine...
Suliman, C.; Cruceru, C.; Moldoveanu, F.
Efficient Feature Selection Methods in Chinese Spam Filtering
Directory of Open Access Journals (Sweden)
Full Text Available This study, from the perspective of Chinese Spam Filtering, focuses on efficient feature selection methods. It expounds the traditional feature selection algorithms including Document Frequency (DF, Information Gain (IG, the Mutual Information (MI, Chi-square (CHI and Knowledge Gain (KG which is proposed in my previous study. Testing these methods on exposing Chinese spam data set, the results show that in Chinese spam corpus CHI and KG can efficiently extract valid features for spam classifications.
Xu Yan
A New Approach for Cluster Based Collaborative Filters
Directory of Open Access Journals (Sweden)
Full Text Available In modern E-Commerce it is not easy for customers to find the best suitable goods of their interest as more and more information is placed on line (like movies, audios, books, documents etc.... So in order to provide most suitable information of high value to customers of an e-commerce business system, a customized recommender system is required. Collaborative Filtering has become a popular technique for reducing this information overload. While traditional collaborative filtering systems have been a substantial success, there are several problems that researchers and commercial applications have identified: the early rater problem, the sparsity problem, and the scalability problem. This paper contains literature survey on cluster based collaborative filter and an approach to construct it.
R. Venu Babu,
Passive solar in China: traditional and new
Energy Technology Data Exchange (ETDEWEB)
The authors' observations of a tradition of passive solar architecture in northern China are described. Tendencies for modern buildings to depart from this tradition are noted. Major passive solar research programs are discussed and experimental buildings are illustrated. It is concluded that the Chinese could realize a major advantage by combining their strong tradition of passive solar architecture with modern insulation methods and improved glazing systems.
Balcomb, J D; Balcomb, S A
Traditional marketing vs. Internet marketing. A comparison
Digital Repository Infrastructure Vision for European Research (DRIVER)
Title: Traditional marketing vs. Internet marketing: A comparison Problem: Marketing is an important strategy for businesses and it contains numerous effective tools. Traditional marketing has been in use for many years and nowadays Internet has brought new ways of doing business for companies and that has affected marketing. What are the main differences between Internet marketing and traditional marketing? Which one of the two approaches contains the most used and effective marketing tools ...
Varfan, Mona; Shima, Alfa
A cloud filtering method for microwave upper tropospheric humidity measurements
Directory of Open Access Journals (Sweden)
Full Text Available The paper presents a cloud filtering method for upper tropospheric humidity (UTH measurements at 183.31±1.00 GHz. The method uses two criteria: The difference between the brightness temperatures at 183.31±7.00 and 183.31±1.00 GHz, and a threshold for the brightness temperature at 183.31±1.00 GHz. The robustness of this cloud filter is demonstrated by a mid-latitudes winter case-study.
The paper then studies different biases on UTH climatologies. Clouds are associated with high humidity, therefore the dry bias introduced by cloud filtering is discussed and compared to the wet biases introduced by the clouds radiative effect if no filtering is done. This is done by means of a case study, and by means of a stochastic cloud database with representative statistics for midlatitude conditions.
The consistent result is that both cloud wet bias (0.8% RH and cloud filtering dry bias (–2.4% RH are modest for microwave data, where the numbers given are for the stochastic cloud dataset. This indicates that for microwave data cloud-filtered UTH and unfiltered UTH can be taken as error bounds for errors due to clouds. This is not possible for the more traditional infrared data, since the radiative effect of clouds is much stronger there.
The focus of the paper is on midlatitude data, since atmospheric data to test the filter for that case were readily available. The filter is expected to be applicable also to subtropical and tropical data, but should be further validated with case studies similar to the one presented here for those cases.
S. A. Buehler
New filter efficiency test for future nuclear grade HEPA filters
International Nuclear Information System (INIS)
We have developed a new test procedure for evaluating filter penetrations as low as 10/sup /minus/9/ at 0.1-?m particle diameter. In comparison, the present US nuclear filter certification test has a lower penetration limit of 10/sup /minus/5/. Our new test procedure is unique not only in its much higher sensitivity, but also in avoiding the undesirable effect of clogging the filter. Our new test procedure consists of a two-step process: (1) We challenge the test filter with a very high concentration of heterodisperse aerosol for a short time while passing all or a significant portion of the filtered exhaust into an inflatable bag; (2) We then measure the aerosol concentration in the bag using a new laser particle counter sensitive to 0.07-?m diameter. The ratio of particle concentration in the bag to the concentration challenging the filter gives the filter penetration as a function of particle diameter. The bad functions as a particle accumulator for subsequent analysis to minimize the filter exposure time. We have studied the particle losses in the bag over time and find that they are negligible when the measurements are taken within one hour. We also compared filter penetration measurements taken in the conventional direct-sampling method with the indirect bag-sampling method and found excellent agreement. 6 refs., 18 figs., 1 tab
Aboriginal Oral Traditions of Australian Impact Craters
We explore Aboriginal oral traditions that relate to Australian meteorite craters. Using the literature, first-hand ethnographic records, and fieldtrip data, we identify oral traditions and artworks associated with four impact sites: Gosses Bluff, Henbury, Liverpool, and Wolfe Creek. Oral traditions describe impact origins for Gosses Bluff and Wolfe Creek craters and non-impact origins of Liverpool and Henbury craters, with Wolfe Creek stories having both impact and non-impact origins. Three impact sites that are believed to have formed during human habitation of Australia - Dalgaranga, Veevers, and Boxhole - do not have associated oral traditions that are reported in the literature.
Hamacher, Duane W
Spatial filters for high average power lasers
A spatial filter includes a first filter element and a second filter element overlapping with the first filter element. The first filter element includes a first pair of cylindrical lenses separated by a first distance. Each of the first pair of cylindrical lenses has a first focal length. The first filter element also includes a first slit filter positioned between the first pair of cylindrical lenses. The second filter element includes a second pair of cylindrical lenses separated by a second distance. Each of the second pair of cylindrical lenses has a second focal length. The second filter element also includes a second slit filter positioned between the second pair of cylindrical lenses.
Erlandson, Alvin C
A double-filter method for nitrocellulose-filter binding: application to protein-nucleic acid interactions.
Digital Repository Infrastructure Vision for European Research (DRIVER)
Nitrocellulose-filter binding is a powerful technique commonly used to study protein-nucleic acid interactions; however, its utility in quantitative studies is often compromised by its lack of precision. To improve precision and accuracy, we have introduced two modifications to the traditional technique: the use of a 96-well dot-blot apparatus and the addition of a DEAE membrane beneath the nitrocellulose membrane. Using the dot-blot apparatus, an entire triplicate set of data spanning 20-24 ...
Comparison Types of Filter Used in Viewing Inner Structure of Materials Using X-Ray Computed Tomography
International Nuclear Information System (INIS)
The inspection of inner structure of materials plays a very important role in safety and quality elements in industry. This process of inspection needs to be carried out in most accurate and efficient manner. Current practice, region of interest is normally being scanned directly to the radiation detector without filtering added. These procedures are assuming perfectly and accurately for the result image reconstruction without justification. While the process of inspection itself may generate unintentionally defects (artefacts). Besides, safety and quality, the use of several filtering techniques can overcome these deficiencies. X-ray computed tomography is a powerful non-invasive imaging technique for viewing an objects inner structures in 2-D or 3-D cross-section images without the need to physically section it. The invention of CT techniques revolutionised the field of medical diagnostic imaging because it provided more detailed and useful information than any previous non-invasive imaging techniques. The method is increasingly being used in industry, aerospace, geosciences and archaeology. This paper describes the comparison of filtering type (aluminium and copper) in X-ray computed tomography system for imaging and visualising of casting material (rear bracket engine mounting). The theoretical aspects of CT scanner, the system configurations and the adopted algorithm for image reconstruction are discussed. The penetrating rays from a 160 kV/10 mA industrial X-ray machine and a bank of Linear Array Detectors (LAD) in combination with a three-axis sample table were used to construct the CT system. The movement of the sample table in vertical, linear and rotary motion is controlled by a Lab View-based software, the x-ray transmission data is collected by using a commercial image grabber package, and the image reconstruction is performed by using the classical Linear Back Projection (LBP) algorithm. Sample of rear bracket engine mounting were scanned using this CT scanner with different type of filters. Some of the reconstructed images are presented in this paper. (author)
Sample-whitened matched filters
Digital Repository Infrastructure Vision for European Research (DRIVER)
A sample-whitened matched filter (SWMF) for a channel with intersymbol interference and additive white Gaussian noise is defined as a linear filter with the properties that its output samples are a sufficient statistic for the MAP estimation of the transmitted sequence and have uncorrelated noise components. These filters are shown to exist for ali realistic channels and the complete set of SWMF's for any channel is determined. It is shown that for nonpathological channels there is a unique S...
Andersen, Ib
Note: cryogenic coaxial microwave filters.
The careful filtering of microwave electromagnetic radiation is critical for controlling the electromagnetic environment for experiments in solid-state quantum information processing and quantum metrology at millikelvin temperatures. We describe the design and fabrication of a coaxial filter assembly and demonstrate that its performance is in excellent agreement with theoretical modelling. We further perform an indicative test of the operation of the filters by making current-voltage measurements of small, underdamped Josephson junctions at 15 mK. PMID:24593404
Tancredi, G; Schmidlin, S; Meeson, P J
FILT - Filtering Indexed Lucene Triples
Digital Repository Infrastructure Vision for European Research (DRIVER)
The Resource Description Framework (RDF) is the W3C recommended standard for data on the semantic web, while the SPARQL Protocol and RDF Query Language (SPARQL) is the query language that retrieves RDF triples by subject, predicate, or object. RDF data often contain valuable information that can only be queried through filter functions. The SPARQL query language for RDF can include filter clauses in order to define specific data criteria, such as full-text searches, numerical filtering, and c...
Stuhr, Magnus
Directory of Open Access Journals (Sweden)
Full Text Available The notion of fuzzy filters was studied by Vicente and Aranguren (1988, Lowen (1979, and Ramakrishnan and Nayagam (2002. The notion of fuzzily compactness was introduced and studied by Ramakrishnan and Nayagam (2002. In this paper, an equivalent condition of fuzzily compactness is studied and a new notion of semi-Hausdorffness on fuzzy filters, which cannot be defined in crisp theory of filters, is introduced and studied.
Geetha Sivaraman
Lead encephalopathy due to traditional medicines.
Traditional medicine use is common in developing countries and increasingly popular in the western world. Despite the popularity of traditional medicines, scientific research on safety and efficacy is limited. However documented fatalities and severe illness due to lead poisoning are increasingly recognized to be associated with traditional medicine use. As society becomes more globalized, it is imperative for pharmacists and health care providers to learn about the safety of traditional medical practices. The information presented educates and alerts pharmacists and health care providers about the potential of traditional medicines to cause lead encephalopathy. Case reports were located through systematic literature searches using MEDLINE, CINAHL, AMED, CISCOM, EMBASE and The Cochrane library from 1966 to the February 2007. Reference lists of identified articles and the authors' own files were also searched. Inclusion criteria were cases of human lead encephalopathy associated with traditional medical practices. There were no restrictions regarding the language of publication. Data were subsequently extracted and summarized in narrative and tabular form. We found 76 cases of lead encephalopathy potentially associated with traditional medicine. Ayurvedic medicines were associated with 5 cases (7%), Middle eastern traditional medicines with 66 cases (87%) and 5 cases (7%) with other traditional medicines. Of the 76 cases, 5% were in adults and 95% were in infants and young children. Of the 4 adult cases, at least one was left with residual neurological impairment. In infants and young children, among 72 cases 8 (11%) were fatal, and at least 15 (21%) had residual neurological deficits. Traditional medicine users should be screened for lead exposure and strongly encouraged to discontinue metal-containing remedies. Therefore, the United States Food and Drug Administration and corresponding agencies in other countries should require and enforce heavy metal testing for all imported traditional medicines and "dietary supplements". PMID:18690981
Karri, Surya K; Saper, Robert B; Kales, Stefanos N
Adaptive filtering and change detection
Adaptive filtering is a branch of digital signal processing which enables the selective enhancement of desired elements of a signal and the reduction of undesired elements. Change detection is another kind of adaptive filtering for non-stationary signals, and is the basic tool in fault detection and diagnosis.This text takes the unique approach that change detection is a natural extension of adaptive filtering, and the broad coverage encompasses both the mathematical tools needed for adaptive filtering and change detection and the applications of the technology. Real engineering applicatio
Gustafsson, Fredrik
Filters for radioactive liquid wastes
International Nuclear Information System (INIS)
In the crud generated in the reactor cooling water for nuclear power plants, iron oxides (hematite and magnetite) are contained as the main components, and also Co, Mn, Fe, Cr exist as radioactive nuclides. A new filter to separate these cruds, nuclepore membrane filter (NPMF), was investigated for its adaptability, and has been adopted as a practical filter for radioactive liquid wastes. The NPMF has such features as the possibility of complete automation of operation, no generation of secondary wastes, and easy maintenance, because the NPMF has uniform circular holes in poly-carbonate thin films, and shows the properties of stable filtering of particulates, capability of back washing, and others. The elements mounted in a practical system have such construction that the membrane is cut in the form of doughnut, and sandwiched with 100 mesh polyester nets (spacer); the obtained unit filter (cassette) is mounted on the stackable plate of the same size; and 80 pieces of this cassette are formed in a filter of 4 m2 filtering area. The performance varies with the properties of suspended matters and the turbidity of wastes. For example, the filtered liquid of 0.1 ppm or less can be obtained when the 1 ?m filter material is used to treat the liquid waste containing 1 to 100 ppm suspended matters. Usually back washed water is produced by about 1/100 of treated liquid wastes. The lifetime of the membrane is expected to be 1 or 2 years if crud is the main component. (Wakatsuki, Y.)
Optimization of integrated polarization filters
This study reports on the design of small footprint, integrated polarization filters based on engineered photonic lattices. Using a rods-in-air lattice as a basis for a TE filter and a holes-in-slab lattice for the analogous TM filter, we are able to maximize the degree of polarization of the output beams up to 98 % with a transmission efficiency greater than 75 %. The proposed designs allow not only for logical polarization filtering, but can also be tailored to output an arbitrary transverse beam profile. The lattice configurations are found using a recently proposed parallel tabu search algorithm for combinatorial optimization problems in integrated photonics.
Gagnon, Denis; Déziel, Jean-Luc; Dubé, Louis J
We derive optimal filters on the sphere in the context of detecting compact objects embedded in a stochastic background process. The matched filter and the scale adaptive filter are derived on the sphere in the most general setting, allowing for directional template profiles and filters. The performance and relative merits of the two optimal filters are discussed. The application of optimal filter theory on the sphere to the detection of compact objects is demonstrated on simulated mock data. A naive detection strategy is adopted, with an initial aim of illustrating the application of the new optimal filters derived on the sphere. Nevertheless, this simple object detection strategy is demonstrated to perform well, even a low signal-to-noise ratio. Code written to compute optimal filters on the sphere (S2FIL), to perform fast directional filtering on the sphere (FastCSWT) and to construct the simulated mock data (COMB) are all made publicly available. (Accompanying code will be made publicly available on publi...
McEwen, J D; Lasenby, A N
Device for filtering gaseous media
International Nuclear Information System (INIS)
The air filter system for gaseous radioactive substances consists of a vertical chamber with filter material (charcoal, e.g. impregnated). On one side of the chamber there is an inlet compartment and an outlet compartment. On the other side a guiding compartment turns the gas flow coming from the natural-air side through the lower part of filter chamber to the upper part of the filter. The gas flow leaves the upper part through the outlet conpartment as cleaned-air flow. The filter material may be filled into the chamber from above and drawn off below. For better utilization of the filter material the filter chamber is separated by means of a wall between the inlet and outlet compartment. This partition wall consist of two sheets arranged one above the other provided with slots which may be superposed in alignment. In this case filter material is tickling from the upper part of the chamber into the lower part avoiding to form a crater in the filter bed. (DG)
Shunt Active Filter in Damping Harmonics Propagation
Digital Repository Infrastructure Vision for European Research (DRIVER)
This paper deals with a hybrid shunt active power filter applied on 500 kV HVDC, after a description of the causes and effects harmonic pollution which may damage equipments and interrupt electric power customers service; in this paper we present the deferent solutions of this problem among one has to study the two most recent types of filtering: passive and hybrid filter. The hybrid filter consists of active filter connected in shunt with passive filter. The hybrid shunt active filter pro...
Tedjini, H.; Meslem, Y.; Rahli, M.; Berbaoui, B.
Building Literacy Traditions: A Family Affair
Children growing up in today's fast-paced, disconnected world are in need of family customs and legacies. Although we tend to associate traditions with elaborate holiday celebrations, these can, and should, be an important part of our day-today lives. In its most basic form, a tradition is a regular event that helps define and distinguish your…
Blasi, MaryJane
Application of isotopes in traditional Chinese medicine
International Nuclear Information System (INIS)
Modernization of traditional Chinese medicine necessitates many new or advanced methods. Among these methods, isotopes are considered to be a convenient, fast and feasible method. The recent advance of isotope's application to traditional Chinese medicine is reviewed. In addition, their present status, problems and prospect are discussed. (authors)
Instructional Design Processes and Traditional Colleges
Traditional colleges who have implemented distance education programs would benefit from using instructional design processes to develop their courses. Instructional design processes provide the framework for designing and delivering quality online learning programs in a highly-competitive educational market. Traditional college leaders play a…
Vasser, Nichole
Marginalized Particle Filtering Framework for Tuning of Ensemble Filters.
Czech Academy of Sciences Publication Activity Database
data assimilationKód oboru RIV: BB - Aplikovaná statistika, opera?ní výzkumImpakt faktor: 2.688, rok: 2011 http://library.utia.cas.cz/separaty/2011/AS/smidl-marginalized particle filtering framework for tuning of ensemble filters.pdf
Šmídl, Václav; Hofman, Radek
A parallel Kalman filter via the square root Kalman filtering
Digital Repository Infrastructure Vision for European Research (DRIVER)
A parallel algorithm for Kalman filtering with contaminated observations is developed. The? parallel implementation is based on the square root version of the Kalman filter (see [3]). This? represents a great improvement over serial implementations reducing drastically computational? costs for each state update.
Grid filter design for a multi-megawatt medium-voltage voltage source inverter
Digital Repository Infrastructure Vision for European Research (DRIVER)
This paper describes the design procedure and performance of an LCL grid filter for a medium-voltage neutral point clamped (NPC) converter to be adopted for a multimegawatt wind turbine. The unique filter design challenges in this application are driven by a combination of the medium voltage converter, a limited allowable switching frequency, component physical size and weight concerns, and the stringent limits for allowable injected current harmonics. Traditional design ...
Rockhill, A. A.; Liserre, M.; Teodorescu, Remus; Rodri?guez Corte?s, Pedro
Designing & FPGA Implementation of IIR Filter Used for detecting clinical information from ECG
Digital Repository Infrastructure Vision for European Research (DRIVER)
This paper describes an approach to design andimplementation of digital filter algorthims based on fieldprogrammable gate arrays (FPGAs).The advantages of FPGAapproach to digital filter implementation include highersampling rates than are available from traditional DSP chips,lower cost than ASIC for moderate volume applications AnECG is a simple and useful test which records the rhythm andelectrical activity of the heart of the patient that suffers fromany heart diseaseWhile recording ECG sig...
Are Supernovae Recorded in Indigenous Astronomical Traditions?
Novae and supernovae are rare astronomical events that would have had an influence on the sky-watching peoples who witnessed them. Although several bright novae/supernovae have been visible during recorded human history, there are many proposed but no confirmed accounts of supernovae in oral traditions or material culture. Criteria are established for confirming novae/supernovae in oral and material culture, and claims from around the world are discussed to determine if they meet these criteria. Australian Aboriginal traditions are explored for possible descriptions of novae/supernovae. Although representations of supernovae may exist in Indigenous traditions, and an account of a nova in Aboriginal traditions has been confirmed, there are currently no confirmed accounts of supernovae in Indigenous oral or material traditions.
Hamacher, Duane W
Vietnamese traditional medicine from a pharmacist's perspective.
Traditional medicine plays an important role in the healthcare system of Vietnam. Vietnamese traditional medicine (VTM) is underpinned by the oriental philosophy and theory of healing. VTM is largely influenced by traditional Chinese medicine, but differs to a certain extent. VTM is largely not evidence-based from a clinical perspective but subclinical research data from the past decades support the traditional use of many herbal VTM drugs. For safe use, knowledge of the occurrence of adverse reactions and herb-drug interactions is necessary. The Vietnamese government supports further development of VTM in a scientific way and integration of VTM with Western medicine. This article first gives an overview of the general aspects of VTM (historical perspective, regulatory aspects, comparison with traditional Chinese medicine, philosophical background, the Vietnamese market situation, quality assurance and formulations), and subsequently focuses on its safe and effective use in Vietnamese clinical pharmacy and medical practice. PMID:22943125
Woerdenbag, Herman J; Nguyen, Tuyen Manh; Vu, Dien Van; Tran, Hung; Nguyen, Dung Tuan; Tran, Thanh Van; De Smet, Peter A G M; Brouwers, Jacobus R B J
Why Breast Cancer Patients Seek Traditional Healers
International Nuclear Information System (INIS)
Traditional healing is a common practice in low and middle income countries such as Malaysia. Eighty percent of Malaysians consult traditional healers or bomoh at some time in their life for health-related issues. The purpose of our study was to explore why breast cancer patients visit traditional healers. This is a qualitative study utilizing in-depth interviews with 11 cancer survivors who sought both traditional and Western medicine. The findings revealed the following reasons for which patients seek traditional healers: (1) recommendation from family and friends, (2) sanction from family, (3) perceived benefit and compatibility, (4) healer credibility, and (5) reservation with Western medicine and system delay. These factors work together and are strongly influenced by the Malaysian cultural context. The issue with the Western health system is common in a developing country with limited health facilities
Application of DFT Filter Banks and Cosine Modulated Filter Banks in Filtering
None given. This is a proposal for a paper to be presented at APCCAS '94 in Taipei, Taiwan. (From outline): This work is organized as follows: Sec. II is devoted to the construction of the new 2m channel under-decimated DFT filter bank. Implementation and complexity of this DFT filter bank are discussed therein. IN a similar manner, the new 2m channel cosine modulated filter bank is discussed in Sec. III. Design examples are given in Sec. IV.
Lin, Yuan-Pei; Vaidyanathan, P. P.
This activity asks students to work in a team to develop a set of rules that can be used to program a SPAM filter for a client. The rules are based on characteristics of the subject lines of emails. Students are given samples of SPAM and non-SPAM subject lines to examine. After their rules are ready, they are given a test set of data to use and are asked to come up with a numerical measure to quantify how well their method (model) works. Each team writes a report describing how their model works and how well it performed on the test data. This activity could serve as an introduction to ideas of classification. Alternatively, the activity could be the basis for student introduction to types of statistical errors.
Minnesota., This P.
Subjective Collaborative Filtering
We present an item-based approach for collaborative filtering. We determine a list of recommended items for a user by considering their previous purchases. Additionally other features of the users could be considered such as page views, search queries, etc... In particular we address the problem of efficiently comparing items. Our algorithm can efficiently approximate an estimate of the similarity between two items. As measure of similarity we use an approximation of the Jaccard similarity that can be computed by constant time operations and one bitwise OR. Moreover we improve the accuracy of the similarity by introducing the concept of user preference for a given product, which both takes into account multiple purchases and purchases of related items. The product of the user preference and the Jaccard measure (or its approximation) is used as a score for deciding whether a given product has to be recommended.
Caruso, Fabrizio; Zarba, Calogero
Kalman filtering implementation with Matlab
Digital Repository Infrastructure Vision for European Research (DRIVER)
1960 und 1961 veröffentlichte Rudolf Emil Kalmen seine Arbeiten über einen rekursiven prädiktiven Filter, der auf dem Gebrauch von rekursiven Algorithmen basiert. Damit revolutionierte er das Feld der Schätzverfahren. Seitdem ist der sogenannte Kalman Filter Gegenstand ausführlicher Forschung und findet bis heute Anwendung in zahlreichen Gebieten.
Kleinbauer, Rachel
Polarizing Filter for Integrated Optics
Polarizing filter for titanium-doped lithium niobate light waveguide suppresses transverse magnetic (TM) mode of light propagation while allowing transverse electric (TE) mode to continue on its way. Filter - lithium niobate crystal - is expected to find many applications in integrated optical circuits.
Ramer, O. G.; Goss, W. C.; Goldstein, R.
Pressure transients across HEPA filters
Energy Technology Data Exchange (ETDEWEB)
Knowledge of HEPA filter effectiveness under various pressure transients is critical to maintaining and assuring nuclear plant safety. The facility now being constructed at New Mexico State University has been designed to provide information that can be used to predict the response of HEPA filters when subjected to various pressure transients.
Gregory, W.S.; Smith, P.R.; Ricketts, C.; Reynolds, G.
Image filtering via generalized scale.
In medical imaging, low signal-to-noise ratio (SNR) and/or contrast-to-noise ratio (CNR) often cause many image processing algorithms to perform poorly. Postacquisition image filtering is an important off-line image processing approach widely employed to enhance the SNR and CNR. A major drawback of many filtering techniques is image degradation by diffusing/blurring edges and/or fine structures. In this paper, we introduce a scale-based filtering method that employs scale-dependent diffusion conductance to perform filtering. This approach utilizes novel object scale information via a concept called generalized scale, which imposes no shape, size, or anisotropic constraints unlike previously published ball scale-based filtering strategies. The object scale allows us to better control the filtering process by constraining smoothing in regions with fine details and in the vicinity of boundaries while permitting effective smoothing in the interior of homogeneous regions. A new quantitative evaluation strategy that captures the SNR to CNR trade-off behavior of filtering methods is presented. The evaluations based on the Brainweb data sets show superior performance of generalized scale-based diffusive filtering over two existing methods, namely, ball scale-based and nonlinear complex diffusion processes. Qualitative experiments based on both phantom and patient magnetic resonance images demonstrate that the generalized scale-based approach leads to better preservation of fine details and edges. PMID:17827051
Souza, Andre; Udupa, Jayaram K; Madabhushi, Anant
Chopped filter for nuclear spectroscopy
International Nuclear Information System (INIS)
Some of the theoretical and practical factors affecting the energy resolution of a spectrometry system are considered, specially those related to t he signal-to-noise ratio, and a time-variant filter with the transfer function of the theoretical optimum filter, during its active time, is proposed. A prototype has been tested and experimental results are presented. (Author)
African Tradition and Global Consumer Culture: Understanding Attachment to Traditional Dress Style in West Africa
Digital Repository Infrastructure Vision for European Research (DRIVER)
This article investigates the attachment of Senegalese to traditional consumption patterns and its effects on the construction of a coherent identity. In particular, we investigate loyalty to traditional dress across multiple occasions and in the face of global consumer culture dominance. To explore the multiplicity of meanings of tradition, this study relies on in-depth interviews, focus groups and a structured means-end analysis. The results reveal that loyalty to tradition enables indiv...
Identification Filtering with fuzzy estimations
Directory of Open Access Journals (Sweden)
Full Text Available A digital identification filter interacts with an output reference model signal known as a black-box output system. The identification technique commonly needs the transition and gain matrixes. Both estimation cases are based on mean square criterion obtaining of the minimum output error as the best estimation filtering. The evolution system represents adaptive properties that the identification mechanism includes considering the fuzzy logic strategies affecting in probability sense the evolution identification filter. The fuzzy estimation filter allows in two forms describing the transition and the gain matrixes applying actions that affect the identification structure. Basically, the adaptive criterion conforming the inference mechanisms set, the Knowledge and Rule bases, selecting the optimal coefficients in distribution form. This paper describes the fuzzy strategies applied to the Kalman filter transition function, and gain matrixes. The simulation results were developed using Matlab©.
J.J Medel J
'Traditional' justice? - The role of traditional authority in traditional justice mechanisms in post-conflict Sierra Leone
Digital Repository Infrastructure Vision for European Research (DRIVER)
The research field of this present thesis is the intersection between traditional authorities and traditional justice mechanisms in the context of post-conflict Sierra Leone. With an increase in civil wars in past decades, questions of how to deal with issues of post-conflict justice and reconciliation have moved to the forefront of the international development agenda. In recent years this field, known as transitional justice, has begun to move away from standardised approaches towar...
Meesenburg, Anna Welin; Dolberg, Lisbeth Carstensen
Reduction of Data Sparsity in Collaborative Filtering based on Fuzzy Inference Rules
Directory of Open Access Journals (Sweden)
Full Text Available Collaborative filtering Recommender system plays avery demanding and significance role in this era ofinternet informationand of course e commerce age.Collaborative filtering predicts user preferencesfrom past user behaviouror user-item relationships.Though it has many advantages it also has somelimitations such as sparsity, scalability, accuracy,cold start problem etc.In this paper we proposed amethod that helps in reducing sparsity to enhancerecommendation accuracy. We developed fuzzyinference ruleswhich is easily to implement andalso gives better result. Acomparison experiment isalsoperformingwith two previous methods,Traditional Collaborative Filtering (TCF andHybrid User Model Technique (HUMCF.
A tisha Sachan
Deconvolution filtering: Temporal smoothing revisited.
Inferences made from analysis of BOLD data regarding neural processes are potentially confounded by multiple competing sources: cardiac and respiratory signals, thermal effects, scanner drift, and motion-induced signal intensity changes. To address this problem, we propose deconvolution filtering, a process of systematically deconvolving and reconvolving the BOLD signal via the hemodynamic response function such that the resultant signal is composed of maximally likely neural and neurovascular signals. To test the validity of this approach, we compared the accuracy of BOLD signal variants (i.e., unfiltered, deconvolution filtered, band-pass filtered, and optimized band-pass filtered BOLD signals) in identifying useful properties of highly confounded, simulated BOLD data: (1) reconstructing the true, unconfounded BOLD signal, (2) correlation with the true, unconfounded BOLD signal, and (3) reconstructing the true functional connectivity of a three-node neural system. We also tested this approach by detecting task activation in BOLD data recorded from healthy adolescent girls (control) during an emotion processing task. Results for the estimation of functional connectivity of simulated BOLD data demonstrated that analysis (via standard estimation methods) using deconvolution filtered BOLD data achieved superior performance to analysis performed using unfiltered BOLD data and was statistically similar to well-tuned band-pass filtered BOLD data. Contrary to band-pass filtering, however, deconvolution filtering is built upon physiological arguments and has the potential, at low TR, to match the performance of an optimal band-pass filter. The results from task estimation on real BOLD data suggest that deconvolution filtering provides superior or equivalent detection of task activations relative to comparable analyses on unfiltered signals and also provides decreased variance over the estimate. In turn, these results suggest that standard preprocessing of the BOLD signal ignores significant sources of noise that can be effectively removed without damaging the underlying signal. PMID:24768215
Bush, Keith; Cisler, Josh
Pollution abatement activities and traditional productivity
Energy Technology Data Exchange (ETDEWEB)
This study models the joint production of good and bad output production and calculates traditional productivity when bad output production is regulated and when it is unregulated. We apply this model to data for U.S. coal-fired electric power plants for 1985-1995 and compare rates of productivity and technical change to gain an understanding of the association between pollution abatement activities and traditional rates of productivity and technical change. While traditional productivity and technical change associated with abatement activities decline, we conclude they are not statistically significant. (author)
Faere, Rolf [Oregon State University, Department of Economics and Department of Agriculture and Resource Economics, Corvallis, OR 97331 (United States); Grosskopf, Shawna [Oregon State University, Department of Economics, Corvallis, OR 97331 (United States); Pasurka, Carl A. Jr. [U.S. Environmental Protection Agency, Office of Policy, Economics and Innovation (1809T), 1200 Pennsylvania Ave., N.W., Washington, D.C. 20460 (United States)
Filtered Backprojection Reconstruction with Depth-Dependent Filtering*
A direct filtered-backprojection (FBP) reconstruction algorithm is presented for circular cone-beam computed tomography (CB-CT) that allows the filter operation to be applied efficiently with shift-variant band-pass characteristics on the kernel function. Our algorithm is derived from the ramp-filter based FBP method of Feldkamp et al. and obtained by decomposing the ramp filtering into a convolution involving the Hilbert kernel (global operation) and a subsequent differentiation operation (local operation). The differentiation is implemented as a finite difference of two (Hilbert filtered) data samples and carried out as part of the backprojection step. The spacing between the two samples, which defines the low-pass characteristics of the filter operation, can thus be selected individually for each point in the image volume. We here define the sample spacing to follow the magnification of the divergent-beam geometry and thus obtain a novel, depth-dependent filtering algorithm for circular CB-CT. We evaluate this resulting algorithm using computer-simulated CB data and demonstrate that our algorithm yields results where spatial resolution and image noise are distributed much more uniformly over the field-of-view, compared to Feldkamp's approach.
Dennerlein, Frank; Kunze, Holger; Noo, Frederic
Position USBL/DVL Sensor-based Navigation Filter in the presence of Unknown Ocean Currents
This paper presents a novel approach to the design of globally asymptotically stable (GAS) position filters for Autonomous Underwater Vehicles (AUVs) based directly on the nonlinear sensor readings of an Ultra-short Baseline (USBL) and a Doppler Velocity Log (DVL). Central to the proposed solution is the derivation of a linear time-varying (LTV) system that fully captures the dynamics of the nonlinear system, allowing for the use of powerful linear system analysis and filtering design tools that yield GAS filter error dynamics. Simulation results reveal that the proposed filter is able to achieve the same level of performance of more traditional solutions, such as the Extended Kalman Filter (EKF), while providing, at the same time, GAS guarantees, which are absent for the EKF.
Morgado, M; Oliveira, P; Silvestre, C
Shunt Active Filter in Damping Harmonics Propagation
Directory of Open Access Journals (Sweden)
Full Text Available This paper deals with a hybrid shunt active power filter applied on 500 kV HVDC, after a description of the causes and effects harmonic pollution which may damage equipments and interrupt electric power customers service; in this paper we present the deferent solutions of this problem among one has to study the two most recent types of filtering: passive and hybrid filter. The hybrid filter consists of active filter connected in shunt with passive filter. The hybrid shunt active filter proposed is based on three levels PWM inverter and characterized by detecting the harmonic current flowing into the passive filter and controlled by notch algorithm. This structure has been applied on a test HVDC power system, is presented as a technical solution makes it possible to eliminate the disadvantages from passive filtering, and also economic price of active filtering part. The simulation results justified the effectiveness of this type of filter face of the classic passive filter.
Inferior Vena Cava Filter Placement and Removal
Inferior Vena Cava Filter Placement and Removal • Overview In an inferior vena cava filter placement procedure, interventional radiologists use image guidance to place a filter in the inferior vena cava (IVC), the large vein in the abdomen ...
L'Araméen et la Tradition Juive
Digital Repository Infrastructure Vision for European Research (DRIVER)
Sont étudiées, sur des critčres linguistiques, les divers variantes diachroniques et diatopiques de l'Araméen depuis 3000 ans. Est évoquée la place de cette langue avec ces variantes dans la tradition juive.
The Reformed tradition as public theology
Directory of Open Access Journals (Sweden)
Full Text Available This article is a South African perspective of a Black African reflection on the publicity of Reformed faith. Whilst the notion of public theology is fairly new, the article argues, it is important to define the 'public' of the type of public theology to which Reformed faith and tradition could be linked. As a confessional tradition, Reformed faith is intrinsically public, the article demonstrates. The publicity of this tradition is however ambivalent and tainted. I attempt to show this by discussing two important tenets of the Reformed Tradition: sola scriptura and sola fide, within the festering wounds of Black African colonialism, apartheid and the hegemony of the neoliberal paradigm in the 21st century.
Vuyani S. Vellem
Directory of Open Access Journals (Sweden)
Full Text Available Transylvania and the Banat are two historical regions that gave birth to several domestic animal breeds. Over the last 15 years, number have sunken dramatically, because these local breeds have been greatly replaced by imported ones. Although very many so- called agrotouristic pensions are now on the market, only about 1% of them promote real traditional food products obtained from local animal breeds. Only few people, especially old people, know traditional recipes older than two or three hundred years and the youth totally ignore them. On the one hand, a large variety of names for different products have appeared on the market, but they are manufactured by big firms and do not have the quality of the traditional products. On the other hand, small producers often have hygiene problems. The reinforcement of traditional products can only occur if people know the quality and the value of the products obtained from the local animal breeds, many of them being endangered species.
Intrusions of Modernity on a Traditional Culture.
Presents a teacher's impressions of India, gathered during a Fulbright-sponsored study tour. Examines modernizing influences in the midst of traditional culture, religious cultural groups and potential religious conflict, women's status, and problems due to overpopulation. (CH)
Thomas, Anne Horsfall
Memory, History and the Classical Tradition
Digital Repository Infrastructure Vision for European Research (DRIVER)
Memory' is often confused and mistaken for myth; this is in turn connected with the widespread use of mistaking collective mythology and common myth for the idea of a 'collective memory'. This essay discusses memory and history terminology in the context of the generic concept 'classical tradition'. The case study explored here - the nineteenth-century Walhalla 'temple' near Regensburg in Southern Germany - is an attempt to discuss the classical tradition, focusing on archaeology and architec...
Traditional foods of Black Sea Countries
Digital Repository Infrastructure Vision for European Research (DRIVER)
INTRODUCTION: Traditional dietary patterns, generally beneficial to health as judged over time, should be promoted beyond the native country's borders. Scientific data is a prerequisite for the successful promotion of a sustainable diet. The Mediterranean diet is a distinguished example of such a dietary pattern. Accumulating scientific evidence has established it globally as a model diet. OBJECTIVES: A framework for the investigation of traditional foods, aiming primarily at t...
Vasilopoulou, E.; Dilis, V.; Finglas, P.; Costa, H. S.; D'antuono, L. F.; Trichopoulou, A.; on behalf of the BaSeFood Black Sea area partners
Portfolio choice beyond the traditional approach
Digital Repository Infrastructure Vision for European Research (DRIVER)
This paper surveys asset allocation methods that extend the traditional approach. An important feature of the traditional approach is that measures the risk and return tradeoff in terms of mean and variance of final wealth. However, there are also other important features that are not always made explicit in terms of investor's wealth, information, and horizon: The investor makes a single portfolio choice based only on the mean and variance of her final financial wealth and she knows the re...
Penaranda, Francisco
Digital Repository Infrastructure Vision for European Research (DRIVER)
Traditional food products is insufficient capitalized value of the Romanian rural space. Certification methodology of such a product existent documentation mentions the need to present the method of production and how is ensured the food safety. Here arises confusion between the notion of quality and safety. Safety is an explicit requirement of quality, is included in the quality assurance system, but does not overlap. Processor must find all resources needed to respect the traditionalism...
Oana Brînzan; Eugenia ?igan
Traditional beer processing in Tanzania: development needs
Directory of Open Access Journals (Sweden)
Full Text Available A general account of the status of the traditional alcoholic beverages in Tanzania is presented with special focus on sorghum beers. The traditional procedure used to prepare Mtama (sorghum beer, a popular alcoholic beverage of Tanzania is described. Based on the personal experience of the author himself and on reports in the literature the problem areas requiring technological improvement on this beer are outlined. The case for immediate research needs, aimed at developing a commercially viable Mtama beer, is argued.
B. Tiisekwa
Traditional Chinese Medicine for Senile Dementia
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Traditional Chinese Medicine (TCM) has a 3000 years' history of human use. A literature survey addressing traditional evidence from human studies was done, with key result that top 10 TCM herb ingredients including Poria cocos, Radix polygalae, Radix glycyrrhizae, Radix angelica sinensis, and Radix rehmanniae were prioritized for highest potential benefit to dementia intervention, related to the highest frequency of use in 236 formulae collected from 29 ancient Pharmacopoeias, ancient formula...
Zhihong Lin; Jie Gu; Jin Xiu; Tingyan Mi; Jie Dong; Jyoti Kumar Tiwari
Critically assessing traditions: the case of Meghalaya
Digital Repository Infrastructure Vision for European Research (DRIVER)
In the North East Indian state of Meghalaya, the main tussle for power and control over resources seems to be between the tribal organisations that have been designated by the Constitution of India as 'traditional institutions', and the constitutionally elected bodies. In this tug-of-war it is the common citizens who suffer, and this suffering varies from being deprived of access to civic amenities, to being victims of ethnic violence. In this situation the representatives of traditional inst...
Hayek, Mill and the liberal tradition
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This book considers the relationship between Hayek and Mill, taking issues with Hayek s criticism of Mill and providing a broader perspective of the liberal tradition. Featuring contributions from the likes of Ross Emmett, Leon Montes and Robert Garnett, these chapters ask whether Hayek had an accurate reading of the ideas of Mill and Smith, as well as considering themes such as sympathy and analytical egalitarianism that play a large part in the liberal tradition, but less in work of Hayek T...
Digital Repository Infrastructure Vision for European Research (DRIVER)
Many scientific studies are focused on antioxidant activities in prevention, on their beneficial role for health status and age retardation. The main source of antioxidants for humans is the diet.The aim of the study was to present data for antioxidant compounds in traditional Bulgarian foods, typical of Bulgarian diet. The traditional foods selected for this study were: onion, pepper, tomatoes, green beans, apples, and wild fruit varieties – blueberries, blackberries, raspberries. Antioxid...
Music transcription within Irish traditional music
Digital Repository Infrastructure Vision for European Research (DRIVER)
Transcribing Irish traditional music is an open-field of research. The oral transmission of the music between generations explains the lack of transcription until recent times. The music can be played solo, which permits the player to exploit the variety of ornamentation types, in unison, and also with the accompaniment of a harmonic instrument. Different signal processing applications for transcribing Irish traditional music are presented in this thesis, including onset, ornamentation and pi...
Traditional beer processing in Tanzania: development needs
Digital Repository Infrastructure Vision for European Research (DRIVER)
A general account of the status of the traditional alcoholic beverages in Tanzania is presented with special focus on sorghum beers. The traditional procedure used to prepare Mtama (sorghum) beer, a popular alcoholic beverage of Tanzania is described. Based on the personal experience of the author himself and on reports in the literature the problem areas requiring technological improvement on this beer are outlined. The case for immediate research needs, aimed at developing a commercially vi...
Tiisekwa, B.
Gas separating and venting filter
International Nuclear Information System (INIS)
A gas separating and venting filter is disclosed for separating gases and liquids and venting the gases in any position of the filter. A housing defines an interior chamber, with inlet and outlet means for the flow of liquid into and out of the chamber. A hydrophilic filter membrane extends along one major wall of the chamber, with longitudinally extending open-sided passageways in the one major wall facing the hydrophilic filter membrane and leading to the outlet means. The hydrophilic filter membrane is flexible for ballooning into the passageways in response to a build-up of pressure in the chamber to restrict and/or cut off the flow of liquid through the passageways. A hydrophobic filter membrane extends along substantially the entire length of an opposite major wall of the chamber between the inlet and outlet means for passing gas but not liquid therethrough. A plurality of spaced vent holes are formed in the opposite major wall for venting gas which has passed through the hydrophobic filter membrane
Soot oxidation in fibrous filters
Energy Technology Data Exchange (ETDEWEB)
Acetylene soot deposited in glass fiber and Na/sub 2/CO/sub 3/ coated quartz filters oxidizes at a rate about two orders of magnitude faster than soot in quartz filters, as a result of catalysis by sodium compounds present in glass. EDX analysis of partially oxidized soot particles showed that sodium from glass fibers was transported to the dendritic soot structures. The oxidation process in the immobilized soot could be described by the shrinking core model. The oxidation rate of soot is proportional to the oxygen partial pressure for both catalyzed and non-catalyzed soot oxidation. The apparent activation energies of soot oxidized in glass fiber and Na-quartz filters ranged from 21.2 +/- 0.7 to 32.5 +/- 1.1 kcal/mole depending on the sodium/soot ratio. The reaction rate depends on the sodium to soot ratio. The Na-quartz filters are more temperature resistant (>980/sup 0/C) and catalytically more active even if the sodium loading is much less than that of glass fiber filters. The salt is deposited on the fiber surface which may facilitate the transport of sodium to the soot. Also the impregnation process deposits more salt on the fine fibers as a result of the higher surface to volume ratio for fine fibers. In ambient pollution studies, glass fiber filters and quartz filters have been used to collect aerosol particles for subsequent carbon analysis by oxidation at high temperatures.
Lin, C.
International Nuclear Information System (INIS)
Purpose: To prevent the reduction in the activity of radioactive iodine adsorbent material at high temperature. Constitution: Regenerated cellulose type fiberous activated carbon with the pore volume of 0.08 cc/g is reactivated by impregnating to support 10% by weight of magnesium acetate to obtain fiberous activated carbon with the pore volume 0.40 cc/g for the pores having diameter between 30 - 300 A. 60 parts of the activated carbon, 40 parts of breaching graft pulp made of coniferous trees and 7 parts by weight of polyvinyl alcohol fibers are subjected to a paper- making process to obtain activated carbon paper. Then, it is molded into a single side corrugated sheet, which is immersed in an ethanol solution containing 20% by weight of triethylenediamine then dried and molded into a honeycomb filter. It is necessary that the activated carbon material has pore volume of more than 5 cc/g for the pores having diameter between 30 - 300 A. (Horiuchi, T.)
Collaborative Filtering Recommender Systems
Directory of Open Access Journals (Sweden)
Full Text Available Recommender Systems are software tools and techniques for suggesting items to users by considering their preferences in an automated fashion. The suggestions provided are aimed at support users in various decision-making processes. Technically, recommender system has their origins in different fields such as Information Retrieval (IR, text classification, machine learning and Decision Support Systems (DSS. Recommender systems are used to address the Information Overload (IO problem by recommending potentially interesting or useful items to users. They have proven to be worthy tools for online users to deal with the IO and have become one of the most popular and powerful tools in E-commerce. Many existing recommender systems rely on the Collaborative Filtering (CF and have been extensively used in E-commerce .They have proven to be very effective with powerful techniques in many famous E-commerce companies. This study presents an overview of the field of recommender systems with current generation of recommendation methods and examines comprehensively CF systems with its algorithms.
Mehrbakhsh Nilashi
Electrothermally tunable MEMS filters
MEMS resonators have potential application in the area of frequency selective devices (e.g., gyroscopes, mass sensors, etc.). In this paper, design of electro thermally tunable resonators is presented. SOIMUMPs process is used to fabricate resonators with springs (beams) and a central mass. When voltage is applied, due to joule heating, temperature of the conducting beams goes up. This results in increase of electrical resistance due to mobility degradation. Due to increase in the temperature, springs start softening and therefore the fundamental frequency decreases. So for a given structure, one can modify the original fundamental frequency by changing the applied voltage. Coupled thermal effects result in non-uniform heating. It is observed from measurements and simulations that some parts of the beam become very hot and therefore soften more. Consequently, at higher voltages, the structure (equivalent to a single resonator) behaves like coupled resonators and exhibits peak splitting. In this mode, the given resonator can be used as a band rejection filter. This process is reversible and repeatable. For the designed structure, it is experimentally shown that by varying the voltage from 1 to 16V, the resonant frequency could be changed by 28%.
Prasad, A. V. S. S.; K. P., Venkatesh; Bhat, Navakanta; Pratap, Rudra
International Nuclear Information System (INIS)
Present day electronic detectors used in high energy physics make it possible to obtain high event rates and it is likely that future experiments will face even higher data rates than at present. The complexity of the apparatus increases very rapidly with time and also the criteria for selecting desired events become more and more complex. So complex in fact that the fast trigger system cannot be designed to fully cope with it. The interesting events become thus contaminated with multitudes of uninteresting ones. To distinguish the 'good' events from the often overwhelming background of other events one has to resort to computing techniques. Normally this selection is made in the first part of the analysis of the events, analysis normally performed on a powerful scientific computer. This implies however that many uninteresting or background events have to be recorded during the experiment for subsequent analysis. A number of undesired consequences result; and these constitute a sufficient reason for trying to perform the selection at an earlier stage, in fact ideally before the events are recorded on magnetic tape. This early selection is called 'on-line filtering' and it is the topic of the present lectures. (Auth.)
Image Filtering Methods for Biomedical Applications
Digital Repository Infrastructure Vision for European Research (DRIVER)
Filtering is a key step in digital image processing and analysis. It is mainly used for amplification or attenuation of some frequencies depending on the nature of the application. Filtering can either be performed in the spatial domain or in a transformed domain. The selection of the filtering method, filtering domain, and the filter parameters are often driven by the properties of the underlying image. This thesis presents three different kinds of biomedical image filtering applications, wh...
Niazi, M. Khalid Khan
Optimal Bit and Power Constrained Filter Banks
Digital Repository Infrastructure Vision for European Research (DRIVER)
In this dissertation, two filter banks optimization problems are studied. The first problem is the optimization of filter banks used in a subband coder under a bit constraint. In the second problem, a multiple input multiple output communication system is optimized under a power constraint. Three different cases on the filter lengths are considered: unconstrained length filter banks, transforms, and finite impulse response filter banks with arbitrary given filter lengths. In source coding an...
Hjřrungnes, Are
PTFE media for ULPA filter; ULPA filter yo PTFE rozai
Energy Technology Data Exchange (ETDEWEB)
Outlined herein are polytetrafluoroethylene (PTFE) media for ULPA filters. PTFE is a tetrafluoroethylene resin more stable than any other fluorine resins. Water repellency, resistance to chemicals and purity are important characteristics of PTFE as a medium for ULPA filters. For production of a membrane, a mixture of finely powdered PTFE and a lubricating agent is extruded into a sheet, which is treated to remove the agent into a porous structure. A PTFE medium is completed by compositing the PTFE membrane with a non-woven fabric, to keep the membrane shape intact by protecting it from damages during the filter production process. The ULPA filters with a PTFE membrane fall into two general types; high collection efficiency and low pressure drop types. Their major advantages include high collection efficiency, low pressure drop, small quantities of impurities (boron-free) and high resistance to chemicals. 8 refs., 4 figs., 5 tabs.
Ichiyasu, S. [Japan Gore-Tex Inc., Tokyo (Japan)
Pragmatic circuits signals and filters
Pragmatic Circuits: Signals and Filters is built around the processing of signals. Topics include spectra, a short introduction to the Fourier series, design of filters, and the properties of the Fourier transform. The focus is on signals rather than power. But the treatment is still pragmatic. For example, the author accepts the work of Butterworth and uses his results to design filters in a fairly methodical fashion. This third of three volumes finishes with a look at spectra by showing how to get a spectrum even if a signal is not periodic. The Fourier transform provides a way of dealing wi
Eccles, William
Image Filtering via Generalized Scale
Digital Repository Infrastructure Vision for European Research (DRIVER)
In medical imaging, low signal-to-noise ratio (SNR) and/or contrast-to-noise ratio (CNR) often cause many image processing algorithms to perform poorly. Postacquisition image filtering is an important off-line image processing approach widely employed to enhance the SNR and CNR. A major drawback of many filtering techniques is image degradation by diffusing/blurring edges and/or fine structures. In this paper, we introduce a scale-based filtering method that employs scale-dependent diffusion ...
Souza, Andre; Udupa, Jayaram K.; Madabhushi, Anant
Determination of 'dynamic filter factor'
International Nuclear Information System (INIS)
The aim of this work was to experimentally determine the 'dynamic filter factor' in symmetrical fields for energies of 6 MV and 15 MV and to compare these results with values obtained by treatment planning system (Cad Plan) under the same conditions. So that, is possible to attribute, for treatment calculation with fields of irradiation that use dynamic filter, the same depth dose percentage used for opened field, without filter. In this way, is validated the system of planning CAD PLAN calculation used in this Institution
Energy Technology Data Exchange (ETDEWEB)
DuPont Lanxide Composites, Inc. undertook a sixty-month program, under DOE Contract DEAC21-94MC31214, in order to develop hot gas candle filters from a patented material technology know as PRD-66. The goal of this program was to extend the development of this material as a filter element and fully assess the capability of this technology to meet the needs of Pressurized Fluidized Bed Combustion (PFBC) and Integrated Gasification Combined Cycle (IGCC) power generation systems at commercial scale. The principal objective of Task 3 was to build on the initial PRD-66 filter development, optimize its structure, and evaluate basic material properties relevant to the hot gas filter application. Initially, this consisted of an evaluation of an advanced filament-wound core structure that had been designed to produce an effective bulk filter underneath the barrier filter formed by the outer membrane. The basic material properties to be evaluated (as established by the DOE/METC materials working group) would include mechanical, thermal, and fracture toughness parameters for both new and used material, for the purpose of building a material database consistent with what is being done for the alternative candle filter systems. Task 3 was later expanded to include analysis of PRD-66 candle filters, which had been exposed to actual PFBC conditions, development of an improved membrane, and installation of equipment necessary for the processing of a modified composition. Task 4 would address essential technical issues involving the scale-up of PRD-66 candle filter manufacturing from prototype production to commercial scale manufacturing. The focus would be on capacity (as it affects the ability to deliver commercial order quantities), process specification (as it affects yields, quality, and costs), and manufacturing systems (e.g. QA/QC, materials handling, parts flow, and cost data acquisition). Any filters fabricated during this task would be used for product qualification tests being conducted by Westinghouse at Foster-Wheeler's Pressurized Circulating Fluidized Bed (PCFBC) test facility in Karhula, Finland. Task 5 was designed to demonstrate the improvements implemented in Task 4 by fabricating fifty 1.5-meter hot gas filters. These filters were to be made available for DOE-sponsored field trials at the Power Systems Development Facility (PSDF), operated by Southern Company Services in Wilsonville, Alabama.
E.S. Connolly; G.D. Forsythe
Gas cleaning with Granular Filters
Digital Repository Infrastructure Vision for European Research (DRIVER)
The panel bed filter (PBF) is a granular filter patented by A. M. Squires in the late sixties. PBFs consist of louvers with stationary, granular beds. Dust is deposited in the top layers and on the bed surface when gas flows through. PBFs are resistant to high temperatures, variations in the gas flow and hot particles. The filter is cleaned by releasing a pressure pulse in the opposite direction of the bulk flow (a puff back pulse). A new louver geometry patented by A. M. Squires is the filte...
Natvig, Ingunn Roald
Attitude Representations for Kalman Filtering
The four-component quaternion has the lowest dimensionality possible for a globally nonsingular attitude representation, it represents the attitude matrix as a homogeneous quadratic function, and its dynamic propagation equation is bilinear in the quaternion and the angular velocity. The quaternion is required to obey a unit norm constraint, though, so Kalman filters often employ a quaternion for the global attitude estimate and a three-component representation for small errors about the estimate. We consider these mixed attitude representations for both a first-order Extended Kalman filter and a second-order filter, as well for quaternion-norm-preserving attitude propagation.
Markley, F. Landis; Bauer, Frank H. (Technical Monitor)
A taxonomy fuzzy filtering approach
Digital Repository Infrastructure Vision for European Research (DRIVER)
Our work proposes the use of topic taxonomies as part of a filtering language. Given a taxonomy, a classifier is trained for each one of its topics. The user is able to formulate logical rules combining the available topics, e.g. (Topic1 AND Topic2) OR Topic3, in order to filter related documents in a stream. Using the trained classifiers, every document in the stream is assigned a belief value of belonging to the topics of the filter. These belief values are then aggregated using logical ope...
Vrettos S.; Stafylopatis A.
Filtering Electrocardiogram Signals Using the Extended Kalman Filter
Digital Repository Infrastructure Vision for European Research (DRIVER)
In this paper the Extended Kalman Filter (EKF) has been used for the filtering of Electrocardiogram (ECG) signals. The method is based on a previously nonlinear dynamic model proposed for the generation of synthetic ECG signals. The results show that the EKF may be used as a powerful tool for the extraction of ECG signals from noisy measurements; which is the state of the art in applications such as the noninvasive extraction of fetal cardiac signals from maternal abdominal signals.
Sameni, Reza; Shamsollahi, M. B.; Jutten, Christian
3D noise power spectrum applied on clinical MDCT scanners: effects of reconstruction algorithms and reconstruction filters
The noise power spectrum (NPS) is the reference metric for understanding the noise content in computed tomography (CT) images. To evaluate the noise properties of clinical multidetector (MDCT) scanners, local 2D and 3D NPSs were computed for different acquisition reconstruction parameters. A 64- and a 128-MDCT scanners were employed. Measurements were performed on a water phantom in axial and helical acquisition modes. CT dose index was identical for both installations. Influence of parameters such as the pitch, the reconstruction filter (soft, standard and bone) and the reconstruction algorithm (filtered-back projection (FBP), adaptive statistical iterative reconstruction (ASIR)) were investigated. Images were also reconstructed in the coronal plane using a reformat process. Then 2D and 3D NPS methods were computed. In axial acquisition mode, the 2D axial NPS showed an important magnitude variation as a function of the z-direction when measured at the phantom center. In helical mode, a directional dependency with lobular shape was observed while the magnitude of the NPS was kept constant. Important effects of the reconstruction filter, pitch and reconstruction algorithm were observed on 3D NPS results for both MDCTs. With ASIR, a reduction of the NPS magnitude and a shift of the NPS peak to the low frequency range were visible. 2D coronal NPS obtained from the reformat images was impacted by the interpolation when compared to 2D coronal NPS obtained from 3D measurements. The noise properties of volume measured in last generation MDCTs was studied using local 3D NPS metric. However, impact of the non-stationarity noise effect may need further investigations.
Miéville, Frédéric A.; Bolard, Gregory; Benkreira, Mohamed; Ayestaran, Paul; Gudinchet, François; Bochud, François; Verdun, Francis R.
Between tradition and renewal: Some considerations about the use of tradition in reformed theology
Directory of Open Access Journals (Sweden)
Full Text Available In the theology and practice of the Christian church a tension between tradition and renewal exists. This essay focuses on this tension to provide a first step of methodological reflection to deal with it. Firstly, this tension is illustrated from the reformed perspective of sola scripturathat led to criticism of the tradition on the one hand, whilst understanding the reformed movement as part of the tradition on the other hand. A danger of unqualified sola scriptura is subjectivity. Subsequently, the importance of tradition is elaborated from the perspective of the church as the body of Christ across all ages. This implies that Christians should study and love the traditional theology because of the fundamental unity of the church that transcends cultural diversity. Rejecting tradition will cut the church from its historical and spiritual roots. Thirdly, this raises the question whether the church is imprisoned by tradition, as well as the problem of the relation between tradition and renewal. In response, it is argued that the doctrine of incarnation guarantees openness to history. With the help of the philosophical and Christian view on structural contingency, the belief that tradition is principally open to renewal is defended. Some examples are given as illustrations of how classic theological concepts can be reframed in our postmodern context. The last part of this essay concludes with the insight of Cyprian that only the conveyed tradition can be renewed, implying that renewal is in essence not a new theology, but a new application of apostolic theology.
Willem van Vlastuin
High Speed FPGA Implementation of FIR Filter for DSP Applications
Directory of Open Access Journals (Sweden)
Full Text Available Signal processing ranks among the most demanding applications of digital design concepts. It is a mature technology domain wherein the demands for enhanced performance and reduced resource utilization have risen exponentially over the years. Field Programmable Gate Array (FPGA design technology has becoming the preferred platform for evaluating and implementing signal processing algorithms. The advantages of the FPGA approach to digital filter implementation include higher sampling rates than are available from traditional DSP chips, lower costs than an application specific integrated circuit (ASIC for moderate volume applications, and more flexibility than the alternate approaches. Since many current FPGA architectures are in-system programmable, the configuration of the device may be changed to implement different functionality if required. This paper describes an approach to the implementation of digital filter based on field programmable gate arrays (FPGAs which is flexible and provides performance comparable or superior to traditional approaches, lowpower, area-efficient re-configurable digital signal processing architecture that is tailored for the realization of arbitrary response Finite impulse response (FIR filters.
Rakhi Thakur
A personalized web page content filtering model based on segmentation
In the view of massive content explosion in World Wide Web through diverse sources, it has become mandatory to have content filtering tools. The filtering of contents of the web pages holds greater significance in cases of access by minor-age people. The traditional web page blocking systems goes by the Boolean methodology of either displaying the full page or blocking it completely. With the increased dynamism in the web pages, it has become a common phenomenon that different portions of the web page holds different types of content at different time instances. This paper proposes a model to block the contents at a fine-grained level i.e. instead of completely blocking the page it would be efficient to block only those segments which holds the contents to be blocked. The advantages of this method over the traditional methods are fine-graining level of blocking and automatic identification of portions of the page to be blocked. The experiments conducted on the proposed model indicate 88% of accuracy in filter...
Kuppusamy, K S; 10.5121/ijist.2012.2104
A Level Set Filter for Speckle Reduction in SAR Images
Directory of Open Access Journals (Sweden)
Full Text Available Despite much effort and significant progress in recent years, speckle removal for Synthetic Aperture Radar (SAR image still is a challenging problem in image processing. Unlike the traditional noise filters, which are mainly based on local neighborhood statistical average or frequencies transform, in this paper, we propose a speckle reduction method based on the theory of level set, one form of curvature flow propagation. Firstly, based on partial differential equation, the Lee filter can be cast as a formulation of anisotropic diffusion function; furthermore, we continued to deduce it into a level set formulation. Level set flow into the method allows the front interface to propagate naturally with topological changes, where the speed is proportional to the curvature of the intensity contours in an image. Hence, small speckle will disappear quickly, while large scale interfaces will be slow to evolve. Secondly, for preserving finer detailed structures in images when smoothing the speckle, the evolution is switched between minimum or maximum curvature speed depending on the scale of speckle. The proposed method has been illustrated by experiments on simulation image and ERS-2 SAR images under different circumstances. Its advantages over the traditional speckle reduction filter approaches have also been demonstrated.
Xiaoxia Huang
Design of Narrow Band FIR Filters
Directory of Open Access Journals (Sweden)
Full Text Available A new concept for the design of finite impulse response (FIR filters is introduced here. This analytical approach has led to three fundamental and new results. First, a differential equation for the approximating polynomial of the filter is developed. Second, the linear differential equation is solved by iteration, yielding an algorithm for recursive evaluation of the impulse response of a filter. Finally, the degree equation of the filter is introduced. We present the design of 4 types of narrow band FIR filters: the maximally at notch FIR filter, the equiripple notch FIR filter, the equiripple DC-notch FIR filter and the equiripple comb FIR filter. Equiripple filters are optimal in the Chebyshev sense. The design procedure starts with frequency specifications of the filter and ends with a recursive evaluation of the impulse response coefficients refraining from other numerical procedures.
Miroslav Vlcek and Pavel Zahradnik
MATLAB Based Digital IIR Filter Design
Directory of Open Access Journals (Sweden)
Full Text Available a fundamental aspect of signal processing is filtering. Filtering involves the manipulation of the spectrum of a signal by passing or blocking certain portions of the spectrum, depending on the frequency of those portions. In this paper, Digital filters are designed using frequency specifications. Matlab provides different options for digital filter design, which includes function, calls to filter algorithms and a graphical user interface called Sptool. A variety of filter design algorithms are available in Matlab for both IIR and FIR filters. This paper discusses the different options in Matlab to design digital IIR filter. Four types of IIR filters are studied, Butterworth, Chebyshev I, Chebyshev II and Elliptic. Results obtained are plots of magnitude resptype of filter. Results show that the graphical user interface Sptool is a quicker and simpler option than the option of making function calls to the filter algorithms. Results are also coof MATLAB
Samarjeet Singh
Image Enhancement using Filtering Techniques
Directory of Open Access Journals (Sweden)
Full Text Available Image enhancement is used to improve the quality of an image. In this paper, two novel algorithms CB (Center-to-Boundary and BB (Boundary-to-Boundary filters have proposed. These algorithms have implemented for
Krishan Kant Lavania
Filtering device for video signal
International Nuclear Information System (INIS)
A half-frame filter is introduced into the transmission circuit, in series. It has a pass band transfer function in the horizontal plane and a high-pass transfer function in the vertical plane. The filter comprises a digital convolution filter carried over 2n-1 points of a line for n lines, with n being an odd number. The convolution is restricted to three lines, all odd or even depending on the type of half-frame, and to five points per line. The central frequency of this pass-band filter is arranged to correspond to the required resolution of the image. In addition the contours of the image are raised. (authors)
Interference filters for Schmidt telescopes.
The properties of interference filters currently used in the observational program at the Ouda Schmidt Telescope, Kyoto University and at the Bosscha Observatory, Institute of Technology Bandung are described.
Wiramihardja, S. D.; Tsujimura, T.; Sasaki, T.; Kogure, T.; Hidayat, B.; Raharto, M.; Ratag, M.
Energy Technology Data Exchange (ETDEWEB)
The surface acoustic wave (SAW) devices using a ZnO/diamond structure was summarized in this paper including late result on high frequency filter of 3.5GHz by 0.75{mu}m in interdigital transducers on diamond. This technology is applied to 1.5GHz narrow bandwidth filter by resonator type filter. Theoretical studies with new material systems were also performed. Zero temperature coefficient filter can be expected by additional amorphous SiO{sub 2} deposition. By LiNbO{sub 3}/diamond structure, high electromechanical coefficient can be expected with high SAW velocity. The varieties of material systems on SAW and advanced devices based on diamond will find broad applications on high frequency devices in future communication systems.
Shikata, Shinichi; Nakahata, Hideaki; Higaki, Kenjiro [Itami Research Labs., Itami (Japan)] [and others
Digital Repository Infrastructure Vision for European Research (DRIVER)
The objective of this diploma was to determine the effectiveness of two different filtrating systems: BRITA, based on the ion exchange and Oasis, consisting of a complex system of filtering cartridges made of activated carbon and ceramics (so called the green filtrating system). Chemical and microbiological analyses of filtered tap water were performed in order to determine the effectiveness of both filtrating systems. Those parameters were measured which should be removed according to th...
Directory of Open Access Journals (Sweden)
Full Text Available Original design of the narrow-band compact filters based on the high-quality waveguide-dielectric resonator with anisotropic materials has been presented in this work. Designed filters satisfy the contradictory requirements: they provide the narrow frequency band (0.05 ÷ 0.1 % of the main frequency f0 and the low initial losses ?0 ? 1 dB.
A.V. Strizhachenko
Ion trajectories quadrupole mass filters
International Nuclear Information System (INIS)
The present paper aims at bringing some contributions to the understanding of ion motion in quadrupole mass filters. The theoretical treatment of quadrupole mass filter is intended to be a concise derivation of the important physical relationships using Mathieu functions. A simple iterative method of numerical computation has been used to simulate ion trajectories in an ideal quadrupole field. Finally, some examples of calculation are presented with the aid of computer graphics. (Author) 14 Figs., 1 Tab., 20 Refs
Greenfield filters in pulmonary embolism
International Nuclear Information System (INIS)
Pulmonary embolism remains one of the most important causes of sudden hospital deaths. From January 1982 to December 1985 24 Greenfield filters were inserted for the treatment of recurrent pulmonary embolism. Only 1 patient had a possible recurrent pulmonary embolus and 1 patient had angulation and penetration of the vein wall. Radionuclide venography demonstrated that all inferior venae cavae were patent. The mortality rate of 38% was not related to the Greenfield filter
Protein transfer to nitrocellulose filters
International Nuclear Information System (INIS)
The authors report that under their conditions the transfer efficiency of a given protein from a SDS-polyacrylamide gel to nitrocellulose filters depends on its Msub(r)-value. After immunodetection with specific antisera and 125I-labelled protein A, the amount of label bound to each antigen increases linearly with the amount of protein applied to the gel. The 125I-labelled protein A bound to the filter is not removed during successive incubations with different antisera. (Auth.)
Process for washing electromagnetic filters
International Nuclear Information System (INIS)
This process concerns the washing of an electro-magnetic filter used, inter alia, for filtering the drain-off waters of nuclear power station steam generators, by means of a washing water used in closed circuit and freed, after each cleaning, of the solids in suspension it contains, by settlement of these solids. This invention enables the volume of water to be evaporated to be divided by 50, thereby providing a solid assurance of better safety, apart from a very significant saving
Quantized, piecewise linear filter network
Digital Repository Infrastructure Vision for European Research (DRIVER)
A quantization based piecewise linear filter network is defined. A method for the training of this network based on local approximation in the input space is devised. The training is carried out by repeatedly alternating between vector quantization of the training set into quantization classes and equalization of the quantization classes linear filter mean square training errors. The equalization of the mean square training errors is carried out by adapting the boundaries between neighbor qua...
Sřrensen, John Aasted
Sensory pollution from bag-type fiberglass ventilation filters: Conventional filter compared with filters containing various amounts of activated carbon
DEFF Research Database (Denmark)
As ventilation filters accumulate particles removed from the airstream, they become emitters of sensory pollutants that degrade indoor air quality. Previously we demonstrated that an F7 bag-type filter that incorporates activated carbon (a "combination filter") reduces this adverse effect compared to an equivalent filter without carbon. The aim of the present study was to examine how the amount of activated carbon (AC) used in combination filters affects their ability to remove both sensory offending pollutants and ozone. A panel evaluated the air downstream of four different filters after each had continuously filtered outdoor suburban air over a period of 6 months. Interim assessments (mid-term evaluation) were performed after 3 months. During both assessments, four unused filters, identical in type to the loaded filters, were also evaluated. The evaluated filters included a conventional F7 fiberglass filter and three modifications of a bag-type fiberglass combination filter: the "Heavy" corresponded to a commercially available filter containing 400 g of carbon per square meter of filter area, the "Medium" contained half as much carbon (200 g/m(2)), and the "Light" contained a quarter as much carbon (100 g/m(2)). Each filter was weighed at the beginning of the soiling period and after 3 and 6 months of service. Additionally, up- and down-stream ozone concentrations and filter pressure drops were measured monthly. Following 6 months of service, the air downstream of each of the combination filters was judged to be significantly better than the air downstream of the 6-month-old F7 filter, and was comparable to that from an unused F7 filter. Additionally, the combination filters removed more ozone from the air than the F7 filter, with their respective fractional removal efficiencies roughly scaling with their carbon content.
Bekö, Gabriel; Fadeyi, M.O.
Sensory pollution from bag-type fiberglass ventilation filters: Conventional filter compared with filters containing various amounts of activated carbon
Energy Technology Data Exchange (ETDEWEB)
As ventilation filters accumulate particles removed from the airstream, they become emitters of sensory pollutants that degrade indoor air quality. Previously we demonstrated that an F7 bag-type filter that incorporates activated carbon (a ''combination filter'') reduces this adverse effect compared to an equivalent filter without carbon. The aim of the present study was to examine how the amount of activated carbon (AC) used in combination filters affects their ability to remove both sensory offending pollutants and ozone. A panel evaluated the air downstream of four different filters after each had continuously filtered outdoor suburban air over a period of 6 months. Interim assessments (mid-term evaluation) were performed after 3 months. During both assessments, four unused filters, identical in type to the loaded filters, were also evaluated. The evaluated filters included a conventional F7 fiberglass filter and three modifications of a bag-type fiberglass combination filter: the ''Heavy'' corresponded to a commercially available filter containing 400 g of carbon per square meter of filter area, the ''Medium'' contained half as much carbon (200 g/m{sup 2}), and the ''Light'' contained a quarter as much carbon (100 g/m{sup 2}). Each filter was weighed at the beginning of the soiling period and after 3 and 6 months of service. Additionally, up- and down-stream ozone concentrations and filter pressure drops were measured monthly. Following 6 months of service, the air downstream of each of the combination filters was judged to be significantly better than the air downstream of the 6-month-old F7 filter, and was comparable to that from an unused F7 filter. Additionally, the combination filters removed more ozone from the air than the F7 filter, with their respective fractional removal efficiencies roughly scaling with their carbon content. (author)
Bekoe, Gabriel; Clausen, Geo [International Centre for Indoor Environment and Energy, Dept. of Civil Engineering, Technical University of Denmark, Nils Koppels Alle 402, 2800-Lyngby (Denmark); Fadeyi, Moshood Olawale [International Centre for Indoor Environment and Energy, Dept. of Civil Engineering, Technical University of Denmark, Nils Koppels Alle 402, 2800-Lyngby (Denmark); Department of Building, School of Design and Environment, National University of Singapore, 4 Architecture Drive, Singapore 117566 (Singapore); Weschler, Charles J. [International Centre for Indoor Environment and Energy, Dept. of Civil Engineering, Technical University of Denmark, Nils Koppels Alle 402, 2800-Lyngby (Denmark); EOHSI (UMDNJ-RW Johnson Medical School and Rutgers Univ.), Piscataway, NJ 08854 (United States)
This paper describes the performance characteristics of an electronically tunable optical filter based on the electro-optic effect. Like the acousto-optic tunable filter, this device operates by selectively coupling principal polarizations in a birefringent crystal at a phase-matched wavelength by means of a spatially periodic refractive index perturbation. Instead of a traveling acoustic wave, however, the electro-optic tunable filter employs a temporally static electric field. The main advantages of this filter are its very low power consumption and its versatility of passband programming, by virtue of separately addressable voltages under microprocessor control. Two basic embodiments of the filter structure are described, one using longitudinal fields collinear with the light beam, the other using transverse fields in a 'thick waveguide' configuration. Various examples of passband synthesis are described that result from apodizing the amplitude of the applied electric field perturbations. Experimental results of filter transfer characteristics at visible wavelengths are presented for the basic transfer function, for passband broadening, and for sidelobe suppression, together with theoretical computer plots showing excellent agreement. Typical driver voltages are 50 to 100 V.
Lotspeich, J. F.; Stephens, R. R.; Henderson, D. M.
Filtering algorithms using shiftable kernels
It was recently demonstrated in [4][arxiv:1105.4204] that the non-linear bilateral filter \\cite{Tomasi} can be efficiently implemented using an O(1) or constant-time algorithm. At the heart of this algorithm was the idea of approximating the Gaussian range kernel of the bilateral filter using trigonometric functions. In this letter, we explain how the idea in [4] can be extended to few other linear and non-linear filters [18,21,2]. While some of these filters have received a lot of attention in recent years, they are known to be computationally intensive. To extend the idea in \\cite{Chaudhury2011}, we identify a central property of trigonometric functions, called shiftability, that allows us to exploit the redundancy inherent in the filtering operations. In particular, using shiftable kernels, we show how certain complex filtering can be reduced to simply that of computing the moving sum of a stack of images. Each image in the stack is obtained through an elementary pointwise transform of the input image. Thi...
Chaudhury, Kunal Narayan
Color Image Enhancement by an Integral Mask-filtering Approach Employing Nonlinear Transfer Function
Digital Repository Infrastructure Vision for European Research (DRIVER)
We demonstrate a brand-new method to sharpen a color image by using an integral mask-filtering technique. The derivatives between the target pixel and its neighbors are transferred by the cubic root function instead of the traditional linear one. The obtained final image has clearer fine characteristics along with much less overshooting.
Color Image Enhancement by an Integral Mask-filtering Approach Employing Nonlinear Transfer Function
Directory of Open Access Journals (Sweden)
Full Text Available We demonstrate a brand-new method to sharpen a color image by using an integral mask-filtering technique. The derivatives between the target pixel and its neighbors are transferred by the cubic root function instead of the traditional linear one. The obtained final image has clearer fine characteristics along with much less overshooting.
Ching-Chung Yang
The ethics of improving African traditional medical practice: scientific or African traditional research methods?
The disease burden in Africa, which is relatively very large compared with developed countries, has been attributed to various factors that include poverty, food shortages, inadequate access to health care and unaffordability of Western medicines to the majority of African populations. Although for 'old diseases' knowledge about the right African traditional medicines to treat or cure the diseases has been passed from generation to generation, knowledge about traditional medicines to treat newly emerging diseases has to be generated in one way or another. In addition, the existing traditional medicines have to be continuously improved, which is also the case with Western scientific medicines. Whereas one school of thought supports the idea of improving medicines, be they traditional or Western, through scientific research, an opposing school of thought argues that subjecting African traditional medicines to scientific research would be tantamount to some form of colonization and imperialism. This paper argues that continuing to use African traditional medicines for old and new diseases without making concerted efforts to improve their efficacy and safety is unethical since the disease burden affecting Africa may continue to rise in spite of the availability and accessibility of the traditional medicines. Most importantly, the paper commends efforts being made in some African countries to improve African traditional medicine through a combination of different mechanisms that include the controversial approach of scientific research on traditional medicines. PMID:19682966
Nyika, Aceme