WorldWideScience
1

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.)

2

Improvement of wavelet threshold filtered back-projection image reconstruction algorithm  

Science.gov (United States)

Image reconstruction technique has been applied into many fields including some medical imaging, such as X ray computer tomography (X-CT), positron emission tomography (PET) and nuclear magnetic resonance imaging (MRI) etc, but the reconstructed effects are still not satisfied because original projection data are inevitably polluted by noises in process of image reconstruction. Although some traditional filters e.g., Shepp-Logan (SL) and Ram-Lak (RL) filter have the ability to filter some noises, Gibbs oscillation phenomenon are generated and artifacts leaded by back-projection are not greatly improved. Wavelet threshold denoising can overcome the noises interference to image reconstruction. Since some inherent defects exist in the traditional soft and hard threshold functions, an improved wavelet threshold function combined with filtered back-projection (FBP) algorithm was proposed in this paper. Four different reconstruction algorithms were compared in simulated experiments. Experimental results demonstrated that this improved algorithm greatly eliminated the shortcomings of un-continuity and large distortion of traditional threshold functions and the Gibbs oscillation. Finally, the availability of this improved algorithm was verified from the comparison of two evaluation criterions, i.e. mean square error (MSE), peak signal to noise ratio (PSNR) among four different algorithms, and the optimum dual threshold values of improved wavelet threshold function was gotten.

Ren, Zhong; Liu, Guodong; Huang, Zhen

2014-11-01

3

Filtered back-projection algorithm for Compton telescopes  

Science.gov (United States)

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)

2008-03-18

4

Comparative analysis of filtered back-projection algorithms for optoacoustic imaging  

Science.gov (United States)

Various types of cancer remain the second leading cause of death in the world. As a consequence, the detection of these tumors has a vital importance. Optoacoustic imaging (OA), a novel imaging technique, offers high contrast and resolution to detect them by measuring the pressure waves generated by tissues exposed to optical energy. Several algorithms, based on Back Projection (BP) techniques, have been suggested to process OA images in conjunction with signal filtering. In this paper, we compare several BP techniques in combination with different classes of filtering. We apply these techniques first directly to a numerical generated sample image and then to the laser-digitalized image of a tissue phantom, obtaining in both cases the best results in resolution and contrast for a wavelet-based filter.

Gutiérrez, Rebeca; Lamela, Horacio; Gallego, Daniel; Martín, Alberto; Oraevsky, Alexander A.

2010-04-01

5

Characterization of filters applied in filtered back-projection reconstruction for absorption and differential phase-contrast imaging  

International Nuclear Information System (INIS)

In computed X-ray tomography, window functions like ''Ram-Lak'' and ''Hamming'' (absorption) or the ''Hilbert filter'' (phase-contrast) are commonly used for correct tomographic reconstruction and improvement of image quality in the back-projection process. Choosing the appropriate filter, i.e. the adequate weight of the spatial frequencies, is not obvious. For instance, the noise spectrum of phase-contrast tomography differs considerably from absorption tomography. Existing literature does not provide a clear comparison and characterization, neither of absorption nor of differential phase-contrast (DPC) filters corresponding to the target application. In this study, we examine the modulation transfer function (MTF) of a simulated phantom in contrast to its tomographic reconstructions, obtained by forward- and filtered back-projection with different filters. We thereby optimize the reconstruction with respect to sharpness of edges as well as to remaining noise. Those parameters are especially studied using the ''Hilbert filter'' in order to improve frequency weighting, considering amongst others the half-pixel shift method introduced in earlier studies. As a result, we provide a set of rules to facilitate the choice of the appropriate filter for both, absorption and DPC tomography. In biomedical imaging, this filter selection allows for individual contrast enhancement depending on the structure of interest (e.g. bones, soft tissue).

6

Monte Carlo evaluation of the Filtered Back Projection method for image reconstruction in proton computed tomography  

Energy Technology Data Exchange (ETDEWEB)

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.

Cirrone, G.A.P., E-mail: cirrone@lns.infn.it [Laboratori Nazionali del Sud - National Instiute for Nuclear Physics INFN (INFN-LNS), Via S.Sofia 64, 95100 Catania (Italy); Bucciolini, M. [Department of ' Fisiopatologia Clinica' , University of Florence, V.le Morgagni 85, I-50134 Florence (Italy); Bruzzi, M. [Energetic Department, University of Florence, Via S. Marta 3, I-50139 Florence (Italy); Candiano, G. [Laboratorio di Tecnologie Oncologiche HSR, Giglio Contrada, Pietrapollastra-Pisciotto, 90015 Cefalu, Palermo (Italy); Civinini, C. [National Institute for Nuclear Physics INFN, Section of Florence, Via G. Sansone 1, Sesto Fiorentino, I-50019 Florence (Italy); Cuttone, G. [Laboratori Nazionali del Sud - National Instiute for Nuclear Physics INFN (INFN-LNS), Via S.Sofia 64, 95100 Catania (Italy); Guarino, P. [Nuclear Engineering Department, University of Palermo, Via... Palermo (Italy); Laboratori Nazionali del Sud - National Instiute for Nuclear Physics INFN (INFN-LNS), Via S.Sofia 64, 95100 Catania (Italy); Lo Presti, D. [Physics Department, University of Catania, Via S. Sofia 64, I-95123, Catania (Italy); Mazzaglia, S.E. [Laboratori Nazionali del Sud - National Instiute for Nuclear Physics INFN (INFN-LNS), Via S.Sofia 64, 95100 Catania (Italy); Pallotta, S. [Department of ' Fisiopatologia Clinica' , University of Florence, V.le Morgagni 85, I-50134 Florence (Italy); Randazzo, N. [National Institute for Nuclear Physics INFN, Section of Catania, Via S.Sofia 64, 95123 Catania (Italy); Sipala, V. [National Institute for Nuclear Physics INFN, Section of Catania, Via S.Sofia 64, 95123 Catania (Italy); Physics Department, University of Catania, Via S. Sofia 64, I-95123, Catania (Italy); Stancampiano, C. [National Institute for Nuclear Physics INFN, Section of Catania, Via S.Sofia 64, 95123 Catania (Italy); and others

2011-12-01

7

Monte Carlo evaluation of the Filtered Back Projection method for image reconstruction in proton computed tomography  

International Nuclear Information System (INIS)

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.

8

Two-dimensional water temperature reconstruction by filtered back-projection method  

International Nuclear Information System (INIS)

The reconstruction of water temperature in combustion is realized by the tunable diode absorption spectroscopy technique. The model for H2O temperature distribution is assumed as a Gaussian function, ranging from 300 K to 1300 K. Radon transform is used to simulate the experimental results. The reconstruction of temperature distribution is achieved by reconstruction of two temperature-dependent line strengths based on the filtered back-projection method. The temperature reconstruction result agrees well with the original model. Moreover, the influences of the number of projections and random errors in projections on reconstruction are also studied. The simulation results indicate that the decrease in projection number or the increase in noise increases the mean square error of the reconstructed temperature, deteriorating the reconstructed image. The temperature reconstruction can not reveal the original temperature distribution when the projection number reduces to four. (authors)

9

Investigation on PI-line selecting method base on GPU accelerated back-projection filtered VOI reconstruction  

Science.gov (United States)

Reconstruction algorithms based on PI-line or Chord are active subject in CBCT. Among them back-projection filtered (BPF) reconstruction algorithm has obvious influence for its exact reconstruction results and less computations especially in selected volume of interesting (VOI) regions. However, the selecting and sampling method of PI-line segment can directly affect the quality of reconstructed images. In this paper, we proposed a general PI-line selecting scheme to reconstruct VOI regions by using BPF algorithm, which mainly based on the relationship between reconstructed coordinate and PI-line coordinate. The proposed scheme is applicable for GPU accelerated back-projection filtered reconstruction.

Zheng, Han; Yu, Yanyan; Kang, Yan; Liu, Jiren

2010-04-01

10

Comparison of adaptive statistical iterative and filtered back projection reconstruction techniques in brain CT  

Energy Technology Data Exchange (ETDEWEB)

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: renqg83@163.com [Department of Radiology, Hua Dong Hospital of Fudan University, Shanghai 200040 (China); Dewan, Sheilesh Kumar, E-mail: sheilesh_d1@hotmail.com [Department of Geriatrics, Hua Dong Hospital of Fudan University, Shanghai 200040 (China); Li, Ming, E-mail: minli77@163.com [Department of Radiology, Hua Dong Hospital of Fudan University, Shanghai 200040 (China); Li, Jianying, E-mail: Jianying.Li@med.ge.com [CT Imaging Research Center, GE Healthcare China, Beijing (China); Mao, Dingbiao, E-mail: maodingbiao74@163.com [Department of Radiology, Hua Dong Hospital of Fudan University, Shanghai 200040 (China); Wang, Zhenglei, E-mail: Williswang_doc@yahoo.com.cn [Department of Radiology, Shanghai Electricity Hospital, Shanghai 200050 (China); Hua, Yanqing, E-mail: cjr.huayanqing@vip.163.com [Department of Radiology, Hua Dong Hospital of Fudan University, Shanghai 200040 (China)

2012-10-15

11

Single Image Super-Resolution VIA Iterative Back Projection Based Canny Edge Detection and a Gabor Filter Prior  

Directory of Open Access Journals (Sweden)

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

2013-03-01

12

Study on an improved filtered back-projection image reconstruction algorithm combined with wavelet denoising  

Science.gov (United States)

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

2013-09-01

13

Comprehensive analysis of high-performance computing methods for filtered back-projection  

OpenAIRE

This paper provides an extensive runtime, accuracy, and noise analysis of Computed To-mography (CT) reconstruction algorithms using various High-Performance Computing (HPC) frameworks such as: “conventional” multi-core, multi threaded CPUs, Compute Unified Device Architecture (CUDA), and DirectX or OpenGL graphics pipeline programming. The proposed algorithms exploit various built-in hardwired features of GPUs such as rasterization and texture filtering. We compare implementations of the ...

Mendl, Christian B.

2013-01-01

14

[Characterization of the difference between filtered back projection and ordered subsets expectation maximization in spect images using the Wavelet Transform].  

Science.gov (United States)

Efficiency of reconstruction algorithms is important to guarantee quality of Nuclear Medicine tomographic images. The algorithms belong to one of two types: analytical or statistical. The Filtered Back Projection (BP) algorithm belongs to the first group and the Ordered Subsets Expectation Maximization (OSEM) algorithm belongs to the second group. The aim of the present paper was to compare both algorithms by means of the Wavelet Transform (WT). This tool was selected because of its capability to divide the image into different frequency levels without losing information about their spatial position. The WT was applied on the Haar basis without decimation in order to compare matrixes of the same size. Attention was drawn to the relative presence of three typical perturbations: Poisson noise, annular artifacts that express a deficient correction to the planar uniformity and attenuation phenomenon. With these purposes, we studied homologue transversal slices of images of homogeneous distribution of activity. The OSEM algorithm not only greatly improves the filtering of the Poisson noise, but also diminishes the annular artifacts, mainly at the image zone that coincides with the rotation center. The intensity of the attenuation phenomenon was the same with both algorithms, except in the peripheral zone where OSEM showed a slightly higher activity than BP. These observations encourage our interest to continue applying the WT not only to identify the artifacts, but also to try to decrease their deleterious influence on Nuclear Medicine images. PMID:14718146

Pérez, A; Piotrkowski, R; Galli, R; La Mura, G; Peña, F J

2004-01-01

15

Gamma-ray momentum reconstruction from Compton electron trajectories by filtered back-projection  

Science.gov (United States)

Gamma-ray imaging utilizing Compton scattering has traditionally relied on measuring coincident gamma-ray interactions to map directional information of the source distribution. This coincidence requirement makes it an inherently inefficient process. We present an approach to gamma-ray reconstruction from Compton scattering that requires only a single electron tracking detector, thus removing the coincidence requirement. From the Compton scattered electron momentum distribution, our algorithm analytically computes the incident photon's correlated direction and energy distributions. Because this method maps the source energy and location, it is useful in applications, where prior information about the source distribution is unknown. We demonstrate this method with electron tracks measured in a scientific Si charge coupled device. While this method was demonstrated with electron tracks in a Si-based detector, it is applicable to any detector that can measure electron direction and energy, or equivalently the electron momentum. For example, it can increase the sensitivity to obtain energy and direction in gas-based systems that suffer from limited efficiency.

Haefner, A.; Gunter, D.; Plimley, B.; Pavlovsky, R.; Vetter, K.

2014-11-01

16

Chest computed tomography using iterative reconstruction vs filtered back projection (Part 1): evaluation of image noise reduction in 32 patients  

Energy Technology Data Exchange (ETDEWEB)

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.)

Pontana, Francois; Pagniez, Julien; Faivre, Jean-Baptiste; Remy, Jacques [Univ. Lille Nord de France, Department of Thoracic Imaging Hospital Calmette (EA 2694), Lille (France); Flohr, Thomas [Siemens HealthCare, Computed Tomography Division, Forchheim (Germany); Duhamel, Alain [Univ. Lille Nord de France, Department of Medical Statistics, Lille (France); Remy-Jardin, Martine [Univ. Lille Nord de France, Department of Thoracic Imaging Hospital Calmette (EA 2694), Lille (France); Hospital Calmette, Department of Thoracic Imaging, Lille cedex (France)

2011-03-15

17

Comparison of pure and hybrid iterative reconstruction techniques with conventional filtered back projection: Image quality assessment in the cervicothoracic region  

International Nuclear Information System (INIS)

Objectives: To evaluate the impact on image quality of three different image reconstruction techniques in the cervicothoracic region: model-based iterative reconstruction (MBIR), adaptive statistical iterative reconstruction (ASIR), and filtered back projection (FBP). Methods: Forty-four patients underwent unenhanced standard-of-care clinical computed tomography (CT) examinations which included the cervicothoracic region with a 64-row multidetector CT scanner. Images were reconstructed with FBP, 50% ASIR-FBP blending (ASIR50), and MBIR. Two radiologists assessed the cervicothoracic region in a blinded manner for streak artifacts, pixilated blotchy appearances, critical reproduction of visually sharp anatomical structures (thyroid gland, common carotid artery, and esophagus), and overall diagnostic acceptability. Objective image noise was measured in the internal jugular vein. Data were analyzed using the sign test and pair-wise Student's t-test. Results: MBIR images had significant lower quantitative image noise (8.88 ± 1.32) compared to ASIR images (18.63 ± 4.19, P 0.9 for ASIR vs. FBP for both readers). MBIR images were all diagnostically acceptable. Unique features of MBIR images included pixilated blotchy appearances, which did not adversely affect diagnostic acceptability. Conclusions: MBIR significantly improves image noise and streak artifacts of the cervicothoracic region over ASIR and FBP. MBIR is expected to enhance the value of CT examinations for areas where image noise and streak artifacts are problematic

18

Coronary CT angiography: Comparison of a novel iterative reconstruction with filtered back projection for reconstruction of low-dose CT—Initial experience  

International Nuclear Information System (INIS)

Objective: To prospectively compare subjective and objective image quality in 20% tube current coronary CT angiography (cCTA) datasets between an iterative reconstruction algorithm (SAFIRE) and traditional filtered back projection (FBP). Materials and methods: Twenty patients underwent a prospectively ECG-triggered dual-step cCTA protocol using 2nd generation dual-source CT (DSCT). CT raw data was reconstructed using standard FBP at full-dose (Group1a) and 80% tube current reduced low-dose (Group1b). The low-dose raw data was additionally reconstructed using iterative raw data reconstruction (Group2). Attenuation and image noise were measured in three regions of interest and signal-to-noise-ratio (SNR) as well as contrast-to-noise-ratio (CNR) was calculated. Subjective diagnostic image quality was evaluated using a 4-point Likert scale. Results: Mean image noise of group2 was lowered by 22% on average when compared to group1b (p 2 compared to group1b (p 2 (1.88 ± 0.63) was also rated significantly higher when compared to group1b (1.58 ± 0.63, p = 0.004). Conclusions: Image quality of 80% tube current reduced iteratively reconstructed cCTA raw data is significantly improved when compared to standard FBP and consequently may improve the diagnostic accuracy of cCTA

19

Rapid mapping of visual receptive fields by filtered back projection: application to multi-neuronal electrophysiology and imaging.  

Science.gov (United States)

Neurons in the visual system vary widely in the spatiotemporal properties of their receptive fields (RFs), and understanding these variations is key to elucidating how visual information is processed. We present a new approach for mapping RFs based on the filtered back projection (FBP), an algorithm used for tomographic reconstructions. To estimate RFs, a series of bars were flashed across the retina at pseudo-random positions and at a minimum of five orientations. We apply this method to retinal neurons and show that it can accurately recover the spatial RF and impulse response of ganglion cells recorded on a multi-electrode array. We also demonstrate its utility for in vivo imaging by mapping the RFs of an array of bipolar cell synapses expressing a genetically encoded Ca(2+) indicator. We find that FBP offers several advantages over the commonly used spike-triggered average (STA): (i) ON and OFF components of a RF can be separated; (ii) the impulse response can be reconstructed at sample rates of 125 Hz, rather than the refresh rate of a monitor; (iii) FBP reveals the response properties of neurons that are not evident using STA, including those that display orientation selectivity, or fire at low mean spike rates; and (iv) the FBP method is fast, allowing the RFs of all the bipolar cell synaptic terminals in a field of view to be reconstructed in under 4 min. Use of the FBP will benefit investigations of the visual system that employ electrophysiology or optical reporters to measure activity across populations of neurons. PMID:25172952

Johnston, Jamie; Ding, Huayu; Seibel, Sofie H; Esposti, Federico; Lagnado, Leon

2014-11-15

20

Comparison of pure and hybrid iterative reconstruction techniques with conventional filtered back projection: Image quality assessment in the cervicothoracic region  

Energy Technology Data Exchange (ETDEWEB)

Objectives: To evaluate the impact on image quality of three different image reconstruction techniques in the cervicothoracic region: model-based iterative reconstruction (MBIR), adaptive statistical iterative reconstruction (ASIR), and filtered back projection (FBP). Methods: Forty-four patients underwent unenhanced standard-of-care clinical computed tomography (CT) examinations which included the cervicothoracic region with a 64-row multidetector CT scanner. Images were reconstructed with FBP, 50% ASIR-FBP blending (ASIR50), and MBIR. Two radiologists assessed the cervicothoracic region in a blinded manner for streak artifacts, pixilated blotchy appearances, critical reproduction of visually sharp anatomical structures (thyroid gland, common carotid artery, and esophagus), and overall diagnostic acceptability. Objective image noise was measured in the internal jugular vein. Data were analyzed using the sign test and pair-wise Student's t-test. Results: MBIR images had significant lower quantitative image noise (8.88 ± 1.32) compared to ASIR images (18.63 ± 4.19, P < 0.01) and FBP images (26.52 ± 5.8, P < 0.01). Significant improvements in streak artifacts of the cervicothoracic region were observed with the use of MBIR (P < 0.001 each for MBIR vs. the other two image data sets for both readers), while no significant difference was observed between ASIR and FBP (P > 0.9 for ASIR vs. FBP for both readers). MBIR images were all diagnostically acceptable. Unique features of MBIR images included pixilated blotchy appearances, which did not adversely affect diagnostic acceptability. Conclusions: MBIR significantly improves image noise and streak artifacts of the cervicothoracic region over ASIR and FBP. MBIR is expected to enhance the value of CT examinations for areas where image noise and streak artifacts are problematic.

Katsura, Masaki, E-mail: mkatsura-tky@umin.ac.jp [Department of Radiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan); Sato, Jiro; Akahane, Masaaki; Matsuda, Izuru; Ishida, Masanori; Yasaka, Koichiro; Kunimatsu, Akira; Ohtomo, Kuni [Department of Radiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan)

2013-02-15

21

Coronary CT angiography: Comparison of a novel iterative reconstruction with filtered back projection for reconstruction of low-dose CT—Initial experience  

Energy Technology Data Exchange (ETDEWEB)

Objective: To prospectively compare subjective and objective image quality in 20% tube current coronary CT angiography (cCTA) datasets between an iterative reconstruction algorithm (SAFIRE) and traditional filtered back projection (FBP). Materials and methods: Twenty patients underwent a prospectively ECG-triggered dual-step cCTA protocol using 2nd generation dual-source CT (DSCT). CT raw data was reconstructed using standard FBP at full-dose (Group{sub 1}a) and 80% tube current reduced low-dose (Group{sub 1}b). The low-dose raw data was additionally reconstructed using iterative raw data reconstruction (Group{sub 2}). Attenuation and image noise were measured in three regions of interest and signal-to-noise-ratio (SNR) as well as contrast-to-noise-ratio (CNR) was calculated. Subjective diagnostic image quality was evaluated using a 4-point Likert scale. Results: Mean image noise of group{sub 2} was lowered by 22% on average when compared to group{sub 1}b (p < 0.0001–0.0033), while there were no significant differences in mean attenuation within the same anatomical regions. The lower image noise resulted in significantly higher SNR and CNR ratios in group{sub 2} compared to group{sub 1}b (p < 0.0001–0.0232). Subjective image quality of group{sub 2} (1.88 ± 0.63) was also rated significantly higher when compared to group{sub 1}b (1.58 ± 0.63, p = 0.004). Conclusions: Image quality of 80% tube current reduced iteratively reconstructed cCTA raw data is significantly improved when compared to standard FBP and consequently may improve the diagnostic accuracy of cCTA.

Takx, Richard A.P. [Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Department of Radiology, Maastricht University Medical Centre, Maastricht (Netherlands); Schoepf, U. Joseph, E-mail: schoepf@musc.edu [Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Division of Cardiology, Department of Medicine, Medical University of South Carolina, Charleston, SC (United States); Moscariello, Antonio [Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Department of Radiology, Policlinico Universitario Campus Bio-Medico, Rome (Italy); Das, Marco [Department of Radiology, Maastricht University Medical Centre, Maastricht (Netherlands); Rowe, Garrett [Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Schoenberg, Stefan O.; Fink, Christian [Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University (Germany); Henzler, Thomas [Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University (Germany)

2013-02-15

22

Why do commercial CT scanners still employ traditional, filtered back-projection for image reconstruction?  

International Nuclear Information System (INIS)

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)

23

Effect of number of of projections on inverse radon transform based image reconstruction by using filtered back-projection for parallel beam transmission tomography  

International Nuclear Information System (INIS)

This paper present the effect of number of projections on inverse Radon transform (IRT) estimation using filtered back-projection (FBP) technique for parallel beam transmission tomography. The head phantom and the lung phantom have been used in this work. Various filters used in this study include Ram-Lak, Shepp-Logan, Cosin, Hamming and Hanning filters. The slices have been reconstructed by increasing the number of projections through parallel beam transmission tomography keeping the projections uniformly distributed. The Euclidean and Mean Squared errors and peak signal-to-noise ratio (PSNR) have been analyzed for their sensitiveness as functions of number of projections. It has found that image quality improves with the number of projections but at the cost of the computer time. The error has been minimized to get the best approximation of inverse Radon transform (IRT) as the number of projections is enhanced. The value of PSNR has been found to increase from 8.20 to 24.53 dB as the number of projections is raised from 5 to 180 for head phantom. (author)

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Investigation of the quantitative accuracy of 3D iterative reconstruction algorithms in comparison to filtered back projection method: a phantom study  

Science.gov (United States)

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

2014-03-01

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FDG-PET standardized uptake values in normal anatomical structures using iterative reconstruction segmented attenuation correction and filtered back-projection  

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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 (SUV{sub max} and SUV{sub avg}) 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, SUV{sub avg} and SUV{sub max} 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 SUV{sub max} than for higher SUVs and SUV{sub avg}. A set of reference values was obtained for SUV{sub max} and SUV{sub avg} 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.)

Ramos, C.D. [Dept. of Radiology, Nuclear Medicine Service, Memorial Sloan-Kettering Cancer Center, New York (United States); Div. of Nuclear Medicine, Campinas State Univ., Campinas, SP (Brazil); Erdi, Y.E. [Dept. of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York (United States); Gonen, M.; Riedel, E. [Dept. of Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, New York (United States); Yeung, H.W.D.; Macapinlac, H.A.; Larson, S.M. [Dept. of Radiology, Nuclear Medicine Service, Memorial Sloan-Kettering Cancer Center, New York (United States); Chisin, R. [Dept. of Radiology, Nuclear Medicine Service, Memorial Sloan-Kettering Cancer Center, New York (United States); Department of Medical Biophysics and Nuclear Medicine, Hadassah Hebrew University Hospital, Jerusalem (Israel)

2001-02-01

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Chest computed tomography using iterative reconstruction vs filtered back projection (Part 2): image quality of low-dose CT examinations in 80 patients  

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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.)

Pontana, Francois; Pagniez, Julien; Faivre, Jean-Baptiste; Hachulla, Anne-Lise; Remy, Jacques [University Lille Nord de France, Department of Thoracic Imaging, Hospital Calmette (EA 2694), Lille (France); Duhamel, Alain [University Lille Nord de France, Department of Medical Statistics, Lille (France); Flohr, Thomas [Computed Tomography Division, Siemens Healthcare, Forchheim (Germany); Remy-Jardin, Martine [University Lille Nord de France, Department of Thoracic Imaging, Hospital Calmette (EA 2694), Lille (France); Hospital Calmette, Department of Thoracic Imaging, Lille cedex (France)

2011-03-15

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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)

2014-04-15

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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.  

Science.gov (United States)

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 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 reconstructed with MBIR have lower image noise, better image quality, and higher conspicuity and CNR of the PD compared with FBP and ASiR. PMID:24496703

Lin, Xiao-Zhu; Machida, Haruhiko; Tanaka, Isao; Fukui, Rika; Ueno, Eiko; Chen, Ke-Min; Yan, Fu-Hua

2014-06-01

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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.)

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Image quality and radiation dose of low dose coronary CT angiography in obese patients: Sinogram affirmed iterative reconstruction versus filtered back projection  

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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: rui_wang1979@yahoo.cn [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Schoepf, U. Joseph, E-mail: schoepf@musc.edu [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: runze.wu@gmail.com [Siemens Healthcare China, 7 Wangjing Zhonghuan Nanlu, 100102 Beijing (China); Reddy, Ryan P., E-mail: reddyr@musc.edu [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: zhangchuanchen666@163.com [Department of Radiology, Liaocheng People Hospital, 252000 Shandong (China); Yu, Wei, E-mail: yuwei02@gmail.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Liu, Yi, E-mail: liuyi198311@yahoo.cn [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Zhang, Zhaoqi, E-mail: zhaoqi5000@vip.sohu.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China)

2012-11-15

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Image quality of CT angiography with model-based iterative reconstruction in young children with congenital heart disease: comparison with filtered back projection and adaptive statistical iterative reconstruction.  

Science.gov (United States)

To retrospectively evaluate the image quality of CT angiography (CTA) reconstructed by model-based iterative reconstruction (MBIR) and to compare this with images obtained by filtered back projection (FBP) and adaptive statistical iterative reconstruction (ASIR) in newborns and infants with congenital heart disease (CHD). Thirty-seven children (age 4.8 ± 3.7 months; weight 4.79 ± 0.47 kg) with suspected CHD underwent CTA on a 64detector MDCT without ECG gating (80 kVp, 40 mA using tube current modulation). Total dose length product was recorded in all patients. Images were reconstructed using FBP, ASIR, and MBIR. Objective image qualities (density, noise) were measured in the great vessels and heart chambers. The contrast-to-noise ratio (CNR) was calculated by measuring the density and noise of myocardial walls. Two radiologists evaluated images for subjective noise, diagnostic confidence, and sharpness at the level prior to the first branch of the main pulmonary artery. Images were compared with respect to reconstruction method, and reconstruction times were measured. Images from all patients were diagnostic, and the effective dose was 0.22 mSv. The objective image noise of MBIR was significantly lower than those of FBP and ASIR in the great vessels and heart chambers (P statistically significant difference was observed among the three methods (P > 0.05). Mean CNR values were 8.73 for FBP, 14.54 for ASIR, and 22.95 for MBIR. In addition, the subjective image noise of MBIR was significantly lower than those of the others (P reconstruction times were 5.1 ± 2.3 s for FBP and ASIR and 15.1 ± 2.4 min for MBIR. While CTA with MBIR in newborns and infants with CHD can reduce image noise and improve CNR more than other methods, it is more time-consuming than the other methods. PMID:25414055

Son, Sung Sil; Choo, Ki Seok; Jeon, Ung Bae; Jeon, Gye Rok; Nam, Kyung Jin; Kim, Tae Un; Yeom, Jeong A; Hwang, Jae Yeon; Jeong, Dong Wook; Lim, Soo Jin

2014-11-21

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Dose reduction in chest CT: Comparison of the adaptive iterative dose reduction 3D, adaptive iterative dose reduction, and filtered back projection reconstruction techniques  

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Objectives: To assess the effectiveness of adaptive iterative dose reduction (AIDR) and AIDR 3D in improving the image quality in low-dose chest CT (LDCT). Materials and methods: Fifty patients underwent standard-dose chest CT (SDCT) and LDCT simultaneously, performed under automatic exposure control with noise index of 19 and 38 (for a 2-mm slice thickness), respectively. The SDCT images were reconstructed with filtered back projection (SDCT-FBP images), and the LDCT images with FBP, AIDR and AIDR 3D (LDCT-FBP, LDCT-AIDR and LDCT-AIDR 3D images, respectively). On all the 200 lung and 200 mediastinal image series, objective image noise and signal-to-noise ratio (SNR) were measured in several regions, and two blinded radiologists independently assessed the subjective image quality. Wilcoxon's signed rank sum test with Bonferroni's correction was used for the statistical analyses. Results: The mean dose reduction in LDCT was 64.2% as compared with the dose in SDCT. LDCT-AIDR 3D images showed significantly reduced objective noise and significantly increased SNR in all regions as compared to the SDCT-FBP, LDCT-FBP and LDCT-AIDR images (all, P ? 0.003). In all assessments of the image quality, LDCT-AIDR 3D images were superior to LDCT-AIDR and LDCT-FBP images. The overall diagnostic acceptability of both the lung and mediastinal LDCT-AIDR 3D images was comparable to that of the lung and mediastinal SDCT-FBP images. Conclusions: AIDR 3D is superior to AIDR. Intra-individual comparisons between SDCT and LDCT suggest that AIDR 3D allows a 64.2% reduction of the radiation dose as compared to SDCT, by substantially reducing the objective image noise and increasing the SNR, while maintaining the overall diagnostic acceptability.

Yamada, Yoshitake, E-mail: yamada@rad.med.keio.ac.jp [Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582 (Japan); Jinzaki, Masahiro, E-mail: jinzaki@rad.med.keio.ac.jp [Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582 (Japan); Hosokawa, Takahiro, E-mail: hosokawa@rad.med.keio.ac.jp [Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582 (Japan); Tanami, Yutaka, E-mail: tanami@rad.med.keio.ac.jp [Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582 (Japan); Sugiura, Hiroaki, E-mail: hsugiura@rad.med.keio.ac.jp [Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582 (Japan); Abe, Takayuki, E-mail: tabe@z5.keio.jp [Center for Clinical Research, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582 (Japan); Kuribayashi, Sachio, E-mail: skuribay@a5.keio.jp [Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582 (Japan)

2012-12-15

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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: rad053@poh.osaka-med.ac.jp; Juri, Hiroshi; Yoshikawa, Shushi; Narumi, Yoshifumi [Dept. of Radiology, Osaka Medical Coll., Osaka (Japan)

2013-10-15

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Impact of adaptive iterative dose reduction (AIDR) 3D on low-dose abdominal CT - Comparison with routine-dose CT using filtered back projection  

International Nuclear Information System (INIS)

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 s 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

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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 constantssup>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.)

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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 cervica 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.)

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Iterative reconstruction technique vs filter back projection: utility for quantitative bronchial assessment on low-dose thin-section MDCT in patients with/without chronic obstructive pulmonary disease  

International Nuclear Information System (INIS)

The aim of this study was to evaluate the utility of the iterative reconstruction (IR) technique for quantitative bronchial assessment during low-dose computed tomography (CT) as a substitute for standard-dose CT in patients with/without chronic obstructive pulmonary disease. Fifty patients (mean age, 69.2; mean % predicted FEV1, 79.4) underwent standard-dose CT (150mAs) and low-dose CT (25mAs). Except for tube current, the imaging parameters were identical for both protocols. Standard-dose CT was reconstructed using filtered back-projection (FBP), and low-dose CT was reconstructed using IR and FBP. For quantitative bronchial assessment, the wall area percentage (WA%) of the sub-segmental bronchi and the airway luminal volume percentage (LV%) from the main bronchus to the peripheral bronchi were acquired in each dataset. The correlation and agreement of WA% and LV% between standard-dose CT and both low-dose CTs were statistically evaluated. WA% and LV% between standard-dose CT and both low-dose CTs were significant correlated (r > 0.77, p < 0.00001); however, only the LV% agreement between SD-CT and low-dose CT reconstructed with IR was moderate (concordance correlation coefficient = 0.93); the other agreement was poor (concordance correlation coefficient <0.90). Quantitative bronchial assessment via low-dose CT has potential as a substitute for standard-dose CT by using IR and airway luminal volumetry techniques. circle Quantitative bronchial assessment of COPD using low-dose CT is possible. (orig.)

38

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)

2013-07-15

39

Iterative reconstruction technique vs filter back projection: utility for quantitative bronchial assessment on low-dose thin-section MDCT in patients with/without chronic obstructive pulmonary disease  

Energy Technology Data Exchange (ETDEWEB)

The aim of this study was to evaluate the utility of the iterative reconstruction (IR) technique for quantitative bronchial assessment during low-dose computed tomography (CT) as a substitute for standard-dose CT in patients with/without chronic obstructive pulmonary disease. Fifty patients (mean age, 69.2; mean % predicted FEV1, 79.4) underwent standard-dose CT (150mAs) and low-dose CT (25mAs). Except for tube current, the imaging parameters were identical for both protocols. Standard-dose CT was reconstructed using filtered back-projection (FBP), and low-dose CT was reconstructed using IR and FBP. For quantitative bronchial assessment, the wall area percentage (WA%) of the sub-segmental bronchi and the airway luminal volume percentage (LV%) from the main bronchus to the peripheral bronchi were acquired in each dataset. The correlation and agreement of WA% and LV% between standard-dose CT and both low-dose CTs were statistically evaluated. WA% and LV% between standard-dose CT and both low-dose CTs were significant correlated (r > 0.77, p < 0.00001); however, only the LV% agreement between SD-CT and low-dose CT reconstructed with IR was moderate (concordance correlation coefficient = 0.93); the other agreement was poor (concordance correlation coefficient <0.90). Quantitative bronchial assessment via low-dose CT has potential as a substitute for standard-dose CT by using IR and airway luminal volumetry techniques. circle Quantitative bronchial assessment of COPD using low-dose CT is possible. (orig.)

Koyama, Hisanobu; Seki, Shinichiro; Sugimura, Kazuro [Kobe University Graduate School of Medicine, Division of Radiology, Department of Radiology, Kobe, Hyogo (Japan); Ohno, Yoshiharu; Nishio, Mizuho; Matsumoto, Sumiaki; Yoshikawa, Takeshi [Kobe University Graduate School of Medicine, Advanced Biomedical Imaging Research Centre, Kobe (Japan); Kobe University Graduate School of Medicine, Division of Functional and Diagnostic Imaging Research, Department of Radiology, Kobe (Japan); Sugihara, Naoki [Toshiba Medical Systems Corporation, Ohtawara, Tochigi (Japan)

2014-08-15

40

Image reconstruction of simulated specimens using convolution back projection  

Directory of Open Access Journals (Sweden)

Full Text Available This paper reports about the reconstruction of cross-sections of composite structures. The convolution back projection (CBP algorithm has been used to capture the attenuation field over the specimen. Five different test cases have been taken up for evaluation. These cases represent varying degrees of complexity. In addition, the role of filters on the nature of the reconstruction errors has also been discussed. Numerical results obtained in the study reveal that CBP algorithm is a useful tool for qualitative as well as quantitative assessment of composite regions encountered in engineering applications.

Mohd. Farhan Manzoor

2012-04-01

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Cigarette smoke cadmium breakthrough from traditional filters: implications for exposure.  

Science.gov (United States)

Cadmium, a carcinogenic metal, is highly toxic to renal, skeletal, nervous, respiratory and cardiovascular systems. Accurate and precise quantification of mainstream smoke cadmium levels in cigarette smoke is important because of exposure concerns. The two most common trapping techniques for collecting mainstream tobacco smoke particulate for analysis are glass fiber filters and electrostatic precipitators. We observed that a significant portion of total cadmium passed through standard glass fiber filters that are used to trap particulate matter. We therefore developed platinum traps to collect the cadmium that passed through the filters and tested a variety of cigarettes with different physical parameters for quantities of cadmium that passed though the filters. We found glass fiber filters on a rotary smoking machine was significantly higher, ranging from 3.5 to 22.9% of total smoke cadmium deliveries. Cadmium passed through 44 mm filters typically used on linear smoking machines to an even greater degree, ranging from 13.6 to 30.4% of the total smoke cadmium deliveries. Differences in the cadmium that passed through from the glass fiber filters and electrostatic precipitator could be explained in part if cadmium resides in the smaller mainstream smoke aerosol particle sizes. Differences in particle size distribution could have toxicological implications and could help explain the pulmonary and cardiovascular cadmium uptake in smokers. PMID:25313385

Pappas, R Steven; Fresquez, Mark R; Watson, Clifford H

2015-01-01

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Dose reduction in computed tomography of the chest. Image quality of iterative reconstructions at a 50% radiation dose compared to filtered back projection at a 100% radiation dose; Dosisreduktion in der Thorax-CT. Vergleich der Bildqualitaet bei 50% Dosis und iterativer Bildrekonstruktion mit 100% Dosis und gefilterter Rueckprojektion  

Energy Technology Data Exchange (ETDEWEB)

Purpose: The aim of this study was to evaluate the potential of iterative reconstruction (IR) in chest computed tomography (CT) to reduce radiation exposure. The qualitative and quantitative image quality of standard reconstructions with filtered back projection (FBP) and half dose (HD) chest CT data reconstructed with FBP and IR was assessed. Materials and Methods: 52 consecutive patients underwent contrast-enhanced chest CT on a dual-source CT system at 120 kV and automatic exposure control. The tube current was equally split on both tube detector systems. For the HD datasets, only data from one tube detector system was utilized. Thus, FD and HD data was available for each patient with a single scan. Three datasets were reconstructed from the raw data: standard full dose (FD) images applying FBP which served as a reference, HD images applying FBP and IR. Objective image quality analysis was performed by measuring the image noise in tissue and air. The subjective image quality was evaluated by 2 radiologists according to European guidelines. Additional assessment of artifacts, lesion conspicuity and edge sharpness was performed. Results: Image noise did not differ significantly between HD-IR and FD-FBP (p = 0.254) but increased substantially in HD-FBP (p < 0.001). No statistically significant differences were found for the reproduction of anatomical and pathological structures between HD-IR and FD-FBP, subsegmental bronchi and bronchioli. The image quality of HD-FBP was rated inferior because of increased noise. Conclusion: A 50% dose reduction in contrast-enhanced chest CT is feasible without a loss of diagnostic confidence if IR is used for image data reconstruction. Iterative reconstruction is another powerful tool to reduce radiation exposure and can be combined with other dose-saving techniques. (orig.)

May, M.S.; Eller, A.; Stahl, C. [University Hospital Erlangen (Germany). Dept. of Radiology; and others

2014-06-15

43

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 alojection 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.

44

An improved back projection algorithm of ultrasound tomography  

International Nuclear Information System (INIS)

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

45

An improved back projection algorithm of ultrasound tomography  

Science.gov (United States)

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

2014-04-01

46

Controlled source back-projection using seismic arrays for early warning  

Science.gov (United States)

The estimation of earthquake source parameters using seismic arrays has become a powerful research tool over the last decade. More recent studies use back-projection of combined seismic arrays with accurate time corrections, first arrival alignment, and filtering. Although numerous publications show good results using this technique as a post processing tool, real-time reliable source area estimation remains a challenging task. The main shortcoming in real-time processing is spurious results due to seismic noise and off-path arrivals causing random source coordinates, not related to the true source, to be chosen by search algorithms. As a consequence, wide adoption of this approach by Early Warning Centres has not occurred. However, properly chosen constraints on the source parameters can restrict the search field and significantly reduce spurious results, making the final estimate useful for warning systems. To achieve this goal for operational Tsunami Early Warning we introduce the following concepts in source back-projection: only nodes previously used to pre-compute tsunami scenarios are used to form seismic beams; and the possible source search area is limited by a circle that expands with a velocity less than 3.5km/sec from the epicentre. Our final results show that with this approach robust solutions can be obtained in real-time. The most significant information for tsunami modelling, such as the location of the rupture area relative to the epicentre, is retained in the solution. Using a search grid comprised of nodes previously used for tsunami modelling gives an important advantage over an arbitrary dense global grid because the algorithm finds the best matching nodes using observed data, thereby removing human ad-hoc decision making. Tests of the algorithm on a number of recent large earthquakes show that it is a practical approach for Tsunami Early Warning Centres.

Spiliopoulos, S.; Gorbatov, A.

2013-12-01

47

Solving the Electrical Impedance Tomography (EIT inverse problem by the conductivity and back projection methods  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper comparing analysis of back projection method and finite element method for imagine projection reconstruction in EIT (voltages measured on electrodes, attached around the phantom – suitable transfer resistances, by means of solving the forward problem – analysis and iteration procedure of solving the inverse problem is carried out. Advantages of back projection method are absence of necessary in solving the unwieldy (with a great number of finite elements forward problem and solving the reconstruction problem by means of simple projection of measured along equal voltage line transfer resistances. Disadvantage of the back projection method in EIT is absence of information about equal voltage lines trajectory in the case of presence of some weight and structure from standard deviations, EIT task is calculating and monitoring them. Moreover, using back projection method, not real resistivity (conductivity distribution visualization of tomography section elements, but transfer resistances (which are complex functions of these desired resistivities visualization is carried out. So it should not to consider that back projection method is correct in mathematical terms. Modernized finite element method using modification method and conductivity zones method allows avoid (at the expence of considering of phantom structure and iteration procedure structuring by conductivity zones introduction all standard difficulties, which brake using more correct finite element method for solving image reconstruction problem in Electrical Impedance Tomography. Presented thesises are illustrated by example of calculating phantom, which is chosen according  to simple control of results.

I. O. Rybina

2011-06-01

48

A fast marching method based back projection algorithm for photoacoustic tomography in heterogeneous media  

CERN Document Server

This paper presents a numerical study on a fast marching method based back projection reconstruction algorithm for photoacoustic tomography in heterogeneous media. Transcranial imaging is used here as a case study. To correct for the phase aberration from the heterogeneity (i.e., skull), the fast marching method is adopted to compute the phase delay based on the known speed of sound distribution, and the phase delay is taken into account by the back projection algorithm for more accurate reconstructions. It is shown that the proposed algorithm is more accurate than the conventional back projection algorithm, but slightly less accurate than the time reversal algorithm particularly in the area close to the skull. However, the image reconstruction time for the proposed algorithm can be as little as 124 ms when implemented by a GPU (512 sensors, 21323 pixels reconstructed), which is two orders of magnitude faster than the time reversal reconstruction. The proposed algorithm, therefore, not only corrects for the p...

Wang, Tianren

2015-01-01

49

Navigating Earthquake Physics with High-Resolution Array Back-Projection  

Science.gov (United States)

Understanding earthquake source dynamics is a fundamental goal of geophysics. Progress toward this goal has been slow due to the gap between state-of-art earthquake simulations and the limited source imaging techniques based on conventional low-frequency finite fault inversions. Seismic array processing is an alternative source imaging technique that employs the higher frequency content of the earthquakes and provides finer detail of the source process with few prior assumptions. While the back-projection provides key observations of previous large earthquakes, the standard beamforming back-projection suffers from low resolution and severe artifacts. This thesis introduces the MUSIC technique, a high-resolution array processing method that aims to narrow the gap between the seismic observations and earthquake simulations. The MUSIC is a high-resolution method taking advantage of the higher order signal statistics. The method has not been widely used in seismology yet because of the nonstationary and incoherent nature of the seismic signal. We adapt MUSIC to transient seismic signal by incorporating the Multitaper cross-spectrum estimates. We also adopt a "reference window" strategy that mitigates the "swimming artifact," a systematic drift effect in back projection. The improved MUSIC back projections allow the imaging of recent large earthquakes in finer details which give rise to new perspectives on dynamic simulations. In the 2011 Tohoku-Oki earthquake, we observe frequency-dependent rupture behaviors which relate to the material variation along the dip of the subduction interface. In the 2012 off-Sumatra earthquake, we image the complicated ruptures involving orthogonal fault system and an usual branching direction. This result along with our complementary dynamic simulations probes the pressure-insensitive strength of the deep oceanic lithosphere. In another example, back projection is applied to the 2010 M7 Haiti earthquake recorded at regional distance. The high-frequency subevents are located at the edges of geodetic slip regions, which are correlated to the stopping phases associated with rupture speed reduction when the earthquake arrests.

Meng, Lingsen

50

Super-resolution Reconstruction Algorithm Based on Patch Similarity and Back-projection Modification  

Directory of Open Access Journals (Sweden)

Full Text Available We propose an effective super-resolution reconstruction algorithm based on patch similarity and back-projection modification. In the proposed algorithm, we assume patch to be similar in natural images and extract the high-frequency information from the best similar patch to add into goal high-resolution image. In the process of reconstruction, the high-resolution patch is back-projected into the low-resolution patch so as to gain detailed modification. Experiments performed on simulated low-resolution image and real low-resolution image are proved that the proposed super-resolution reconstruction algorithm is effective and efficient to improve the resolution of image and achieve a better visual performance.

Wei-long Chen

2014-07-01

51

A Rayleigh wave back-projection method applied to the 2011 Tohoku earthquake  

Science.gov (United States)

We study the rupture process of the 2011 Tohoku megathrust by analyzing 384 regional strong-motion records using a novel back-projection method for Rayleigh waves with periods between 13 and 100 s. The proposed approach is based on isolating the signal at the selected period with a continuous wavelet transform, and generating the stack using arrival times predicted from detailed fundamental mode Rayleigh wave group velocity maps. We verify the method by back-projecting synthetic time series representing a point source off the coast of Tohoku, which we generate with a 3D finite difference method and a mesh based on the Japan Integrated Velocity Structure Model. Application of the method to K-NET/KiK-net records of the Mw 9.1 Tohoku earthquake reveals several Rayleigh wave emitters, which we attribute to different stages of rupture. Stage 1 is characterized by slow rupture down-dip from the hypocenter. The onset of stage 2 is marked by energetic Rayleigh waves emitted from the region between the JMA hypocenter and the trench within 60 s after hypocentral time. During stage 3 the rupture propagates bilaterally towards the north and south at rupture velocities between 3 and 3.5 km · s-1, reaching Iwate-oki 65 s and Ibaraki-oki 105 s after nucleation. In contrast to short-period back-projections from teleseismic P-waves, which place radiation sources below the Honshu coastline, Rayleigh wave emitters identified from our long-period back-projection are located 50-100 km west of the trench. This result supports the interpretation of frequency-dependent seismic wave radiation as suggested in previous studies.

Roten, Daniel; Miyake, Hiroe; Koketsu, Kazuki

2012-01-01

52

Imaging spatial and temporal seismic source variations at Sierra Negra Volcano, Galapagos Islands using back-projection methods  

Science.gov (United States)

Imaging spatial and temporal seismic source variations at Sierra Negra Volcano, Galapagos Islands using back-projection methods Cyndi Kelly1, Jesse F. Lawrence1, Cindy Ebinger2 1Stanford University, Department of Geophysics, 397 Panama Mall, Stanford, CA 94305, USA 2University of Rochester, Department of Earth and Environmental Science, 227 Hutchison Hall, Rochester, NY 14627, USA Low-magnitude seismic signals generated by processes that characterize volcanic and hydrothermal systems and their plumbing networks are difficult to observe remotely. Seismic records from these systems tend to be extremely 'noisy', making it difficult to resolve 3D subsurface structures using traditional seismic methods. Easily identifiable high-amplitude bursts within the noise that might be suitable for use with traditional seismic methods (i.e. eruptions) tend to occur relatively infrequently compared to the length of an entire eruptive cycle. Furthermore, while these impulsive events might help constrain the dynamics of a particular eruption, they shed little insight into the mechanisms that occur throughout an entire eruption sequence. It has been shown, however, that the much more abundant low-amplitude seismic 'noise' in these records (i.e. volcanic or geyser 'tremor') actually represents a series of overlapping low-magnitude displacements that can be directly linked to magma, fluid, and volatile movement at depth. This 'noisy' data therefore likely contains valuable information about the processes occurring in the volcanic or hydrothermal system before, during and after eruption events. In this study, we present a new method to comprehensively study how the seismic source distribution of all events - including micro-events - evolves during different phases of the eruption sequence of Sierra Negra Volcano in the Galapagos Islands. We apply a back-projection search algorithm to image sources of seismic 'noise' at Sierra Negra Volcano during a proposed intrusion event. By analyzing coherent seismic energy from all possible events to all available receivers, we generate a movie showing how seismic sources change spatially and temporally during the analysis period. This approach utilizes data from the entire seismic record and could ultimately provide a more complete understanding of how seismic sources change throughout the eruptive sequence rather than during a particular eruption event. This information could help to 1) answer fundamental questions about volcano-tectonic processes and 2) make more accurate assessments of volcanic hazards. Preliminary results from application of the methodology to seismic data collected by a dense array of 3-component geophones at El Tatio Geyser Field in northern Chile during October 2012 will also be introduced.

Kelly, C. L.; Lawrence, J. F.; Ebinger, C. J.

2013-12-01

53

Comparison of back projection methods of determining earthquake rupture process in time and frequency domains  

Science.gov (United States)

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.

2013-12-01

54

External force back-projective composition and globally deformable optimization for 3-D coronary artery reconstruction.  

Science.gov (United States)

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. PMID:24503518

Yang, Jian; Cong, Weijian; Chen, Yang; Fan, Jingfan; Liu, Yue; Wang, Yongtian

2014-02-21

55

Seismic energy releases of great earthquakes revealed by a hybrid back-projection method  

Science.gov (United States)

We developed a new back-projection (BP) method that uses teleseismic P-waveforms to integrate the direct P-phase with reflected phases from structural discontinuities near the source and used it to estimate the spatiotemporal distribution of the seismic energy release of great earthquakes. We projected normalized cross-correlations of observed waveforms with corresponding Green's functions onto the seismic source region to obtain a high-resolution image of the seismic energy release. Our modified BP method is similar to previous BP formulations, but the obtained images are related to the slip-rate function on the fault plane, as is the case for seismic source inversion. We therefore call our method the hybrid back-projection (HBP) method. We used a synthetic test to compare the HBP method with the conventional BP method, focusing on the effect of source location and model resolution. We estimated the seismic energy distribution for two frequency bands: 0.1-0.5 Hz (F1) and 0.5-2.0 Hz (F2), and assumed seismic source modes that contain point sources with long rise times to be emphasized in the F1 dataset, and those with short rise times to be emphasized in the F2 dataset. The conventional BP method produced a more blurred image than the HBP method for both frequency bands. The discrepancy between the input and estimated models tended to increase with distance from the hypocenter for both methods. According to the synthetic tests, the effect of the depth phase is a critical problem for the low frequency band, and the Q-effect is important for the high frequency band analysis to estimate accurate rupture velocity especially in the case of small to medium sized earthquakes. Applying this method to teleseismic P-waveform data of great earthquakes, we obtained spatiotemporal distributions of seismic energy release for two frequency bands, a low-frequency dataset and a high-frequency dataset. For example of the 2011 Tohoku-oki earthquake, we found that the energy radiation in the dip direction was strongly frequency dependent. The area of major high-frequency seismic radiation extended only downdip from the hypocenter, whereas the area of major low-frequency seismic radiation propagated both downdip and updip from the hypocenter. We detected a large release of seismic energy near the Japan Trench in the area of maximum slip, when we used only the low-frequency dataset. The timing of this large seismic energy release corresponded to an episode of smooth and rapid slip near the Japan Trench, and reflects the strong dependence of the seismic energy distribution obtained on the frequency band of the input waveform dataset.

Yagi, Y.; Nakao, A.; Kasahara, A.

2012-12-01

56

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.

57

Direct aperture optimization using an inverse form of back-projection.  

Science.gov (United States)

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

2014-01-01

58

Comparative study of projection/back-projection schemes in cryo-EM tomography  

Science.gov (United States)

In the cryo-EM tomography, the projection and back-projection are essential steps in reconstruction the 3D structure of the virus and macromolecules. Distance driven method (DD) is the latest projection /backprojection algorithm originally employed for x-ray computed tomography. This paper is mainly concerned about employing this algorithm to the cryo-EM tomography for reconstruction performance improvement. Existing algorithms used in cryo-EM are pixel-driven and ray driven projection/backprojection, etc. These methods are generally quite time consuming because of their high computational complexity. Furthermore, interpolation artifacts are usually noticeable when the sufficient view and detector samples are not available. The DD is originally proposed to overcome these drawbacks. The interpolation process in DD is done by calculating the overlap area between the detector and pixel boundaries. This procedure largely removes the interpolation artifacts, and reduces the computational complexity significantly. Furthermore, it guarantees that the projection and backprojection are adjoint to each other - a desired property to guarantee the convergence of the iterative reconstruction algorithm. However, unlike the x-ray computed tomography, the cryo-EM tomography problem generally has limited number of the projections, and projection angles are randomly distributed over 4pi steradian. Therefore, the conventional DD should be modified. Rather than computing the boundary overlap in the previous 3-D DD method, we propose a novel DD algorithm based on volume overlap. CCMV virus model is used as testing example. Results are visualized using AMIRA software. Analysis is made upon the advantages and drawbacks of both the existing approaches and distance driven method.

Liu, Yu; Ye, Jong Chul

2006-08-01

59

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 param 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

60

GPU-accelerated back-projection revisited. Squeezing performance by careful tuning  

International Nuclear Information System (INIS)

In recent years, GPUs have become an increasingly popular tool in computed tomography (CT) reconstruction. In this paper, we discuss performance optimization techniques for a GPU-based filtered-backprojection reconstruction implementation. We explore the different optimization techniques we used and explain how those techniques affected performance. Our results show a nearly 50% increase in performance when compared to the current top ranked GPU implementation. (orig.)

61

Using Back-Projection of Surface Waves for Near Real-Time Determination of Global Earthquake Locations, Magnitudes and Mechanisms  

Science.gov (United States)

We will discuss our recent progress in the implementation of a global earthquake detection and analysis system using back-projection of long-period (60-120 s) surface waves. A prototype system for Surface wave Location and Association in Quasi Real time (SLAQR) has been operational in test mode at the United States Geological Survey National Earthquake Information Center (USGS NEIC) using data from around 40 stations of the Global Seismographic Network. The algorithm does not require a human operator to select or analyze data and uses a Rayleigh wave back-projection approach consisting of a continuous progressive conversion of time series into spectrograms and the mapping of those spectrograms onto a grid of locations and origin times. It distinguishes itself by its straightforward adaptation into a routine monitoring system and its constant load approach. This method provides a reliable estimate of the moment of global earthquakes without saturating and thus is particularly useful for large earthquakes. It can also act as a backup to the current NEIC monitoring software and detect events that are missed, or underestimated, by the current system. Particularly important in this regard are long-period “tsunami” earthquakes and slow oceanic transform earthquakes. Our newly added calculation of moment tensors and earthquake depths employs the same spectral parameters already calculated for the determination of magnitudes and locations. We have analyzed the results of this prototype system for the time period of March 2009 to April 2010, to assess its performance and calibrate the produced magnitudes with those in the final NEIC earthquake catalog. Our analysis shows that the system performs well for events greater than magnitude 5.5 and determines reliable magnitudes and locations for global events shallower than 150 km in depth. We have also tested a new extension to this system to determine earthquake moment tensors and depths, and have found that it performs well for very large events, but will require changes to the current system to be functional for smaller earthquakes.

Polet, J.; Thio, H. K.; Earle, P. S.

2010-12-01

62

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)

63

Images of Gravitational and Magnetic Phenomena Derived from 2D Back-Projection Doppler Tomography of Interacting Binary Stars  

CERN Document Server

We have used 2D back-projection Doppler tomography as a tool to examine the influence of gravitational and magnetic phenomena in interacting binaries which undergo mass transfer from a magnetically-active star onto a non-magnetic main sequence star. This multi-tiered study of over 1300 time-resolved spectra of 13 Algol binaries involved calculations of the predicted dynamical behavior of the gravitational flow and the dynamics at the impact site, analysis of the velocity images constructed from tomography, and the influence on the tomograms of orbital inclination, systemic velocity, orbital coverage, and shadowing. The H$\\alpha$ tomograms revealed eight sources: chromospheric emission, a gas stream along the gravitational trajectory, a star-stream impact region, a bulge of absorption or emission around the mass-gaining star, a Keplerian accretion disk, an absorption zone associated with hotter gas, a disk-stream impact region, and a hot spot where the stream strikes the edge of a disk. We described several me...

Richards, Mercedes T; Fisher, John G; Conover, Marshall J

2014-01-01

64

A new non-Fourier tomographic filter for image reconstruction  

International Nuclear Information System (INIS)

This article describes a new class of non-Fourier filter/convolving functions which has been proposed for the popular convolution back projection algorithm in computerized tomography. The convolver coefficients are evaluated directly by geometric considerations involved in the chord-segment inversion (CSI) algorithm. This CSI filter/convolving function is tested on simulated images representing density ranges encountered in damaged nuclear fuel bundles and two-phase steam-water flows

65

Electrical capacitance tomography two-phase oil-gas pipe flow imaging by the linear back-projection algorithm  

Directory of Open Access Journals (Sweden)

Full Text Available Electrical Capacitance Tomography (ECT is a novel technology that can deal with the complexity of two-phase gas-oil flow measurement by explicitly deriving the component distributions on two adjacent planes along a pipeline. One of its most promising applications is the visualization of gas-oil flows. ECT offers some advantages over other tomography modalities, such as no radiation, rapid response, low-cost, being non-intrusive and non-invasive, and the ability to withstand high temperature and high pressure. The linear back-projection (LBP algorithm is one of the most popular methods employed to perform image reconstruction in ECT. Despite its relatively poor accuracy, it is a simple and fast procedure capable of real-time operation in many applications, and it has remained a very popular choice. However, since it was first reported it has lacked a clear formal support in the context of this application. Its only justification has been that it was an adaptation of a method normally used in linear X-ray medical tomography, and the fact that it actually does produce useful (albeit only ‘qualitative’ images. In this paper, one illustrative way of interpreting LBP is presented. It is shown how LBP is actually based on the linearisation of a normalised form of the forward problem. More specifically, the normalised forward problem is approximated by means of a series of hyper-planes. The reconstruction matrix used in LBP is found to be a ‘weighted’ transpose of the linear operator (matrix that defines the linearised normalised forward problem. The rows of this latter matrix contain the information of the sensitivity maps used in LBP.

R. Martin

2005-12-01

66

Characterizing trends in HIV infection among men who have sex with men in Australia by birth cohorts: results from a modified back-projection method  

OpenAIRE

Abstract Background We set out to estimate historical trends in HIV incidence in Australian men who have sex with men with respect to age at infection and birth cohort. Methods A modified back-projection technique is applied to data from the HIV/AIDS Surveillance System in Australia, including "newly diagnosed HIV infections", "newly acquired HIV infections" and "AIDS diagnoses", to estimate trends in HIV incidence over both calendar t...

Wand Handan; Wilson David; Yan Ping; Gonnermann Andrea; McDonald Ann; Kaldor John; Law Matthew

2009-01-01

67

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

68

A new field-of-view autotracking method based on back-projected ray image cross-correlation for online tomography reconstruction.  

Science.gov (United States)

In general, a tomogram cannot be observed immediately after the acquisition of a series of specimen tilt images, but is instead observed after the post-processing of the tilt series alignment, which often requires a substantial amount of time. Moreover, for general specimens, the automatic acquisition of the tilt series is difficult because field-of-view tracking frequently fails as the tilt angle or specimen thickness increases.In this study, we focus on the improvement of the field-of-view autotracking technique for the purpose of online tomography reconstruction and propose a new alternative technique [1,2]. The method we proposed uses a so-called 'back-projected ray image' instead of a specimen tilt image. The back-projected ray image is a cross-section image calculated from each projection image only during reconstruction. As a result of a study on 'ray images', the quality and accuracy of the cross-correlation between a pair of neighboring ray images among the tilt series were observed to be very high compared with those between a pair of projection images. We observed that a back projected ray image reliably cross-correlates with other neighboring ray images at the position of an existing three-dimensional object. The proposed method can therefore consistently track the field-of-view, overcoming the weakness of a conventional image-matching-based method. In addition, the present method is simple, and high speed processing is expected to be achieved because fast Fourier transform (FFT) and inverse fast Fourier transform (IFFT) algorithms can be used.We applied this method to real specimens in online experiments using a TEM and thereby demonstrated its successful performance. Online autotracking experiments with thin-section samples were used to demonstrate the effectiveness of the proposed method. The field-of-view was automatically tracked with high accuracy through a tilt angle range. Furthermore, online tomograms were obtained immediately after the last specimen tilting. With increases in the tracking speed, in situ tomographic observations for analyzing the dynamic behavior might become feasible in the future.jmicro;63/suppl_1/i23-a/DFU058F1F1DFU058F1Fig. 1.Comparison of the proposed autotracking method with the conventional PCF based alignment method using the yeast cell thin-section. a and b: Reconstructed X-Y cross-section images from tracking results at 8° increment angle with the PCF method and with the proposed method. N, nucleus; V, vacuole; NVJ, nucleus-vacuole junction. c: A reconstructed cross-section image from autotracking result at 1° increment angle with the proposed method. (scale bar: 100 nm). PMID:25359820

Tomonaga, Sachihiko; Baba, Misuzu; Baba, Norio

2014-11-01

69

Evaluating low pass filters on SPECT reconstructed cardiac orientation estimation  

Science.gov (United States)

Low pass filters can affect the quality of clinical SPECT images by smoothing. Appropriate filter and parameter selection leads to optimum smoothing that leads to a better quantification followed by correct diagnosis and accurate interpretation by the physician. This study aims at evaluating the low pass filters on SPECT reconstruction algorithms. Criteria for evaluating the filters are estimating the SPECT reconstructed cardiac azimuth and elevation angle. Low pass filters studied are butterworth, gaussian, hamming, hanning and parzen. Experiments are conducted using three reconstruction algorithms, FBP (filtered back projection), MLEM (maximum likelihood expectation maximization) and OSEM (ordered subsets expectation maximization), on four gated cardiac patient projections (two patients with stress and rest projections). Each filter is applied with varying cutoff and order for each reconstruction algorithm (only butterworth used for MLEM and OSEM). The azimuth and elevation angles are calculated from the reconstructed volume and the variation observed in the angles with varying filter parameters is reported. Our results demonstrate that behavior of hamming, hanning and parzen filter (used with FBP) with varying cutoff is similar for all the datasets. Butterworth filter (cutoff > 0.4) behaves in a similar fashion for all the datasets using all the algorithms whereas with OSEM for a cutoff MLEM. This study on evaluating effect of low pass filter cutoff and order on cardiac orientation using three different reconstruction algorithms provides an interesting insight into optimal selection of filter parameters.

Dwivedi, Shekhar

2009-02-01

70

High security and robust optical image encryption approach based on computer-generated integral imaging pickup and iterative back-projection techniques  

Science.gov (United States)

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

2014-04-01

71

Relationship between high-frequency radiation and asperity ruptures, revealed by hybrid back-projection with a non-planar fault model.  

Science.gov (United States)

High-frequency seismic waves are generated by abrupt changes of rupture velocity and slip-rate during an earthquake. Therefore, analysis of high-frequency waves is crucial to understanding the dynamic rupture process. Here, we developed a hybrid back-projection method that considers variations in focal mechanisms by introducing a non-planar fault model that reflects the subducting slab geometry. We applied it to teleseismic P-waveforms of the Mw 8.8 2010 Chile earthquake to estimate the spatiotemporal distribution of high-frequency (0.5-2.0 Hz) radiation. By comparing the result with the coseismic slip distribution obtained by waveform inversion, we found that strong high-frequency radiation can precede and may trigger a large asperity rupture. Moreover, in between the large slip events, high-frequency radiation of intermediate strength was concentrated along the rupture front. This distribution suggests that by bridging the two large slips, this intermediate-strength high-frequency radiation might play a key role in the interaction of the large slip events. PMID:25406638

Okuwaki, Ryo; Yagi, Yuji; Hirano, Shiro

2014-01-01

72

Improved resolution and reduced clutter in ultra-wideband microwave imaging using cross-correlated back projection: experimental and numerical results.  

Science.gov (United States)

Microwave breast cancer detection is based on the dielectric contrast between healthy and malignant tissue. This radar-based imaging method involves illumination of the breast with an ultra-wideband pulse. Detection of tumors within the breast is achieved by some selected focusing technique. Image formation algorithms are tailored to enhance tumor responses and reduce early-time and late-time clutter associated with skin reflections and heterogeneity of breast tissue. In this contribution, we evaluate the performance of the so-called cross-correlated back projection imaging scheme by using a scanning system in phantom experiments. Supplementary numerical modeling based on commercial software is also presented. The phantom is synthetically scanned with a broadband elliptical antenna in a mono-static configuration. The respective signals are pre-processed by a data-adaptive RLS algorithm in order to remove artifacts caused by antenna reverberations and signal clutter. Successful detection of a 7?mm diameter cylindrical tumor immersed in a low permittivity medium was achieved in all cases. Selecting the widely used delay-and-sum (DAS) beamforming algorithm as a benchmark, we show that correlation based imaging methods improve the signal-to-clutter ratio by at least 10?dB and improves spatial resolution through a reduction of the imaged peak full-width half maximum (FWHM) of about 40-50%. PMID:21331362

Jacobsen, S; Birkelund, Y

2010-01-01

73

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

2013-07-01

74

Characterizing trends in HIV infection among men who have sex with men in Australia by birth cohorts: results from a modified back-projection method  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background We set out to estimate historical trends in HIV incidence in Australian men who have sex with men with respect to age at infection and birth cohort. Methods A modified back-projection technique is applied to data from the HIV/AIDS Surveillance System in Australia, including "newly diagnosed HIV infections", "newly acquired HIV infections" and "AIDS diagnoses", to estimate trends in HIV incidence over both calendar time and age at infection. Results Our results demonstrate that since 2000, there has been an increase in new HIV infections in Australian men who have sex with men across all age groups. The estimated mean age at infection increased from ~35 years in 2000 to ~37 years in 2007. When the epidemic peaked in the mid 1980s, the majority of the infections (56% occurred among men aged 30 years and younger; 30% occurred in ages 31 to 40 years; and only ~14% of them were attributed to the group who were older than 40 years of age. In 2007, the proportion of infections occurring in persons 40 years or older doubled to 31% compared to the mid 1980s, while the proportion of infections attributed to the group younger than 30 years of age decreased to 36%. Conclusion The distribution of HIV incidence for birth cohorts by infection year suggests that the HIV epidemic continues to affect older homosexual men as much as, if not more than, younger men. The results are useful for evaluating the impact of the epidemic across successive birth cohorts and study trends among the age groups most at risk.

Wand Handan

2009-09-01

75

Qualitative Evaluation of Filter Function in Brain SPECT  

Directory of Open Access Journals (Sweden)

Full Text Available 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, 6200 reconstruction options were considered. The corresponding planar image of each slice was used as the reference image. The quality of reconstructed images was determined using universal image quality index (UIQI. Four nuclear medicine physicians evaluated the images to choose the best of the filters. Results: Images with best resolution, contrast, smoothness and overall quality were selected by nuclear medicine physicians depending on filters used to generate the best image. A significant difference (p<0.05 between the filters regarding these parameters were observed. Conclusion: The results of this study revealed that maximum resolution and contrast could be obtained using both Metz and Wiener filters. However, the best quality images were generated by using Butterworth filter.

Nahid Yaghobi

2007-06-01

76

An Adjoint-Based Adaptive Ensemble Kalman Filter  

OpenAIRE

A new hybrid ensemble Kalman filter/four-dimensional variational data assimilation (EnKF/4D-VAR) approach is introduced to mitigate background covariance limitations in the EnKF. The work is based on the adaptive EnKF (AEnKF) method, which bears a strong resemblance to the hybrid EnKF/three-dimensional variational data assimilation (3D-VAR) method. In the AEnKF, the representativeness of the EnKF ensemble is regularly enhanced with new members generated after back projection of the EnKF analy...

Song, Hajoon; Hoteit, Ibrahim; Cornuelle, Bruce D.; Luo, Xiaodong; Subramanian, Aneesh C.

2013-01-01

77

High Resolution Telesesimic P-wave Back-Projection Imaging Using Variable Travel Time Corrections: Characterizing Sub-Events of the Great April 11th 2012 Indian Ocean Intraplate Earthquakes  

Science.gov (United States)

Two of the largest strike-slip earthquakes ever recorded occurred off the coast of northern Sumatra on April 11th 2012. The Mw 8.7 mainshock and Mw 8.2 aftershock occurred east of the NinetyEast Ridge in the Wharton Basin, a region of intraplate deformation with prominent fracture zones striking NNE-SSW. The relative lack of geodetic and local seismic data compared to other recent great earthquakes make teleseismic data especially important for understanding the rupture properties of these events. We performed short-period P-wave back-projection imaging using independent networks of stations in Europe and Japan. Preliminary images from the two networks showed similarly complex multi-event sources for the mainshock that indicate rupture occurred along both nodal planes of the gCMT solution, consistent with the locations of early aftershocks. Back-projection images of the Mw 8.2 aftershock showed a single, compact, bilateral rupture corresponding to the NNE-SSW nodal plane of the CMT solution [Yue et al., 2012]. Here we improve upon the resolution and accuracy of our initial back-projection images by estimating station specific travel time corrections that vary across the source region [e.g., Ishii et al., 2007]. These corrections are used to compensate for 3D variations in Earth structure that occur between the source region and the seismometers, and act to focus the array beams. We perform multi-channel cross-correlations of P waves recorded for 7 aftershocks that were (1) distributed broadly around the source region and (2) well-observed at seismometers in Europe. For each seismometer in the array, the 8 measured static corrections are smoothly interpolated over the entire source region with a Kriging method to form a travel time correction surface. These surfaces are then used with an otherwise conventional back-projection approach [Xu et al., 2009] to image the ruptures. Our new images are broadly consistent with our original results, indicating that the extraordinary complexity of the main event is not an artifact of 3D variations in Earth structure. Both preliminary and new back-projection images show mainshock subevents that rupture in directions corresponding to both gCMT nodal planes, with only subtle changes in the location and beam power strength of the sub-events. The results are compared with back-projections of synthetic seismograms for the 4-fault rupture model for the 8.7 event from Yue et al. [2012], to evaluate effects of depth phase and rupture complexity interference. There is more variability in the rupture images of the 8.2 Mw aftershock, with the peak beam energy shifting up to 40-50 km along a NNE-SSW direction. The sensitivity of these results to various Kriging approaches is being investigated.

Kwong, K. B.; Koper, K. D.; Yue, H.; Lay, T.

2012-12-01

78

Kidney Filtering  

Science.gov (United States)

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.

2014-09-18

79

Iterated Filtering  

CERN Document Server

Inference for partially observed Markov process models has been a longstanding methodological challenge with many scientific and engineering applications. Iterated filtering algorithms maximize the likelihood function for partially observed Markov process models by solving a recursive sequence of filtering problems. We present new theoretical results pertaining to the convergence of iterated filtering algorithms implemented via sequential Monte Carlo filters. This theory complements the growing body of empirical evidence that iterated filtering algorithms provide an effective inference strategy for scientific models that have been intractable via alternative methodologies.

Ionides, Edward L; King, Aaron A

2009-01-01

80

Survey on Spam Filtering Techniques  

OpenAIRE

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

2011-01-01

81

Traditional Agriculture and Permaculture.  

Science.gov (United States)

Discusses benefits of combining traditional agricultural techniques with the concepts of "permaculture," a framework for revitalizing traditions, culture, and spirituality. Describes school, college, and community projects that have assisted American Indian communities in revitalizing sustainable agricultural practices that incorporate cultural…

Pierce, Dick

1997-01-01

82

Data assimilation the ensemble Kalman filter  

CERN Document Server

Covers data assimilation and inverse methods, including both traditional state estimation and parameter estimation. This text and reference focuses on various popular data assimilation methods, such as weak and strong constraint variational methods and ensemble filters and smoothers.

Evensen, Geir

2006-01-01

83

Sinogram bow-tie filtering in FBP PET reconstruction.  

Science.gov (United States)

Low-pass filtering of sinograms in the radial direction is the most common practice to limit noise amplification in filtered back projection (FBP) reconstruction of positron emission tomography studies. Other filtering strategies have been proposed to prevent the loss in resolution due to low-pass radial filters, although results have been diverse. Using the well-known properties of the Fourier transform of a sinogram, the authors defined a binary mask that matches the expected shape of the support region in the Fourier domain of the sinogram ("bow tie"). This mask was smoothed by a convolution with a ten-point Gaussian kernel which not only avoids ringing but also introduces a pre-emphasis at low frequencies. A new filtering scheme for FBP is proposed, comprising this smoothed bow-tie filter combined with a standard radial filter and an axial filter. The authors compared the performance of the bow-tie filtering scheme with that of other previously reported methods: Standard radial filtering, angular filtering, and stackgram-domain filtering. All the quantitative data in the comparisons refer to a baseline reconstruction using a ramp filter only. When using the smallest size of the Gaussian kernel in the stackgram domain, the authors achieved a noise reduction of 33% at the cost of degrading radial and tangential resolutions (14.5% and 16%, respectively, for cubic interpolation). To reduce the noise by 30%, the angular filter produced a larger degradation of contrast (3%) and tangential resolution (46% at 10 mm from the center of the field of view) and showed noticeable artifacts in the form of circular blurring dependent on the distance to the center of the field of view. For a similar noise reduction (33%), the proposed bow-tie filtering scheme yielded optimum results in resolution (gain in radial resolution of 10%) and contrast (1% increase) when compared with any of the other filters alone. Experiments with rodent images showed noticeable image quality enhancement when using the proposed bow-tie filtering scheme. PMID:19544783

Abella, M; Vaquero, J J; Soto-Montenegro, M L; Lage, E; Desco, M

2009-05-01

84

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.)

85

Filter assemblies  

International Nuclear Information System (INIS)

A filter assembly for the nuclear industry comprises a plurality of tubular filters welded at one end to a plenum chamber which is made of plastics by rotational moulding and includes an outlet. The other ends of the filters are closed and supported by a plate attached to the plenum chamber by tie rods. A central rod screws into the capture nut at one end and has a fitting, to facilitate remote handling, at the other. The assembly is cheap and destructible after use. (author)

86

Traditional fishing tools  

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

2009-09-01

87

African Traditional Religion (ATR)  

Science.gov (United States)

The African Traditional Religion (ATR) site which hosts the on Bibliography on African Traditional Religion contains several more items of interest, including articles and documents exploring the contact points of ATR with Islam and Christianity, country-by-country statistics on adherents of ATR, and a number of related links.

Isizoh, Chidi D.

1998-01-01

88

Intelligent Optimize Design of LCL Filter for Three-Phase Voltage-Source PWM Rectifier  

OpenAIRE

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

2009-01-01

89

Quality of inverse radon transform-based image reconstruction using various frequency domain filters in parallel beam transmission tomography  

International Nuclear Information System (INIS)

Inverse Radon Transform (IRT) based image reconstruction is of prime importance in various areas of science and engineering in this paper, we have used Filtered Back-Projection technique to find IRT estimate by employing various filters, namely Ram-Lak, shepp-Logan. Cosine, Hamming and Hanning filers for deblurring and emphasizing high frequency components in the projection domain. The head phantom and the lung phantom have been used for carrying out the simulation of 512 * 512 image size. Best results as reconstructed image have been obtained by using Hanning filter. Various image parameters have been used as quality measures including average error, maximum error, peak signal-to-noise ratio, Euclidean error, mean squared error, average error histogram. Variance histogram, mean squared error histogram. Standard deviation histogram, etc. The FBP technique using Hamming filter has been found as effective as FBP Hanning technique in both cases. (author)

90

A nonlinear, image domain filtering method for cardiac PET images  

International Nuclear Information System (INIS)

An adaptive, nonlinear image domain filtering strategy is described which improves positron emission tomography (PET) images. The method was formulated to improve on the linear, low-pass filtering typically applied to each projection in the filtered back-projection (FBP) reconstruction algorithm. The algorithm is a potential alternative to linear smoothing which reduces noise but degrades resolution; this method uses the FBP algorithm for reconstruction, but aims to incorporate some of the statistical information and nonlinear smoothing utilized in iterative reconstruction algorithms. The approach uses sinogram segmentation to separate the sinogram elements with higher and lower signal-to-noise ratios, and then reconstruct each with FBP using a more appropriate choice of filter and cut-off frequency. Also, this algorithm addresses the radial streak artifacts introduced by FBP. The algorithm was evaluated using simulations and clinical data of cardiac PET studies on an ECAT 931 PET scanner. The initial results suggest that this technique has advantages over the current clinical protocol. Images processed with the method show generally improved visual image quality and reduced radial streaks without the introduction of artifacts. In simulations, increased contrast recovery and resolution are realized without an increase in the background noise of the reconstructed images

91

Traditional Urban Aboriginal Religion  

Directory of Open Access Journals (Sweden)

Full Text Available This paper represents a group of Aboriginal people who claim traditional Aboriginal ownership of a large Australian metropol is. They have struggled for at least the last 25 to 30 years to articulate and represent the ir contemporary group identity to the wider Australian society that very often does not take th eir expressions seriously. This is largely because dominant discourses claim that ‘authentic’ Aboriginal culture only exists in remote, pristine areas far away from western societ y and that urban Aboriginal traditions, especially urban religious traditions are, today, d efunct. This paper is an account of one occasion on which such traditional Aboriginal relig ious practice was performed before the eyes of a group of tourists.

Kristina Everett

2009-01-01

92

Oral Tradition Journal  

Science.gov (United States)

Stretching back thousands of years, the oral traditions that have enriched and documented human existence remain a subject of much fascination. The Oral Tradition Journal was founded in 1986 in order to "serve as an international and interdisciplinary forum for discussion of worldwide oral traditions and related forms." The journal is based at the University of Missouri, and visitors to the site can search the entire run of the journal on this site by keyword or author. Clicking over to the "Browse the Journal" area, visitors can look over back issues that include special issues on the Serbo-Croatian oral tradition, performance literature, and the performance artistry of Bob Dylan. The site is a real treat for anyone interested in the subject, and visitors can also learn how to submit their own work for possible inclusion in a forthcoming volume.

2008-01-01

93

Spectral CT Using Multiple Balanced K-Edge Filters.  

Science.gov (United States)

Our goal is to validate a spectral CT system design that uses a conventional X-ray source with multiple balanced Kedge filters. By performing a simultaneously synthetic reconstruction in multiple energy bins, we obtained a good agreement between measurements and model expectations for a reasonably complex phantom. We performed simulation and data acquisition on a phantom containing multiple rods of different materials using a NeuroLogica CT scanner. Five balanced K-edge filters including Molybdenum, Cerium, Dysprosium, Erbium, and Tungsten were used separately proximal to the X-ray tube. For each sinogram bin, measured filtered vector can be defined as a product of a transmission matrix, which is determined by the filters and is independent of the imaging object, and energy-binned intensity vector. The energy-binned sinograms were then obtained by inverting the transmission matrix followed by a multiplication of the filter measurement vector. For each energy bin defined by two consecutive K-edges, a synthesized energy-binned attenuation image was obtained using filtered back-projection reconstruction. The reconstructed attenuation coefficients for each rod obtained from the experiment was in good agreement with the corresponding simulated results. Furthermore, the reconstructed attenuation coefficients for a given energy bin, agreed with National Institute of Standards and Technology reference values when beam hardening within the energy bin is small. The proposed cost-effective system design using multiple balanced K-edge filters can be used to perform spectral CT imaging at clinically relevant flux rates using conventional detectors and integrating electronics. PMID:25252276

Rakvongthai, Yothin; Worstell, William; El Fakhri, Georges; Bian, Junguo; Lorsakul, Auranuch; Ouyang, Jinsong

2014-09-19

94

Traditional Tracking with Kalman Filter on Parallel Architectures  

OpenAIRE

Power density constraints are limiting the performance improvements of modern CPUs. To address this, we have seen the introduction of lower-power, multi-core processors, but the future will be even more exciting. In order to stay within the power density limits but still obtain Moore's Law performance/price gains, it will be necessary to parallelize algorithms to exploit larger numbers of lightweight cores and specialized functions like large vector units. Example technologi...

Cerati, Giuseppe; Elmer, Peter; Lantz, Steven; Macneill, Ian; Mcdermott, Kevin; Riley, Dan; Tadel, Matevz; Wittich, Peter; Wuerthwein, Frank; Yagil, Avi

2014-01-01

95

Notch filter  

Science.gov (United States)

A notch filter for the selective attenuation of a narrow band of frequencies out of a larger band was developed. A helical resonator is connected to an input circuit and an output circuit through discrete and equal capacitors, and a resistor is connected between the input and the output circuits.

Shelton, G. B. (inventor)

1977-01-01

96

IMPLEMENTATION OF DIGITAL FILTERS FOR HIGH THROUGHPUT APPLICATIONS ON FPGA  

OpenAIRE

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...

Pushpa, T.; Venkatlakshmi, M.

2013-01-01

97

[A simulation study to evaluate the statistical noise and spatial resolution in image reconstruction of emission computed tomography--with respect to the optimization of the filter function in the convolution integral].  

Science.gov (United States)

Filtered backprojection method has been commonly used to reconstruct images in the field of the computed tomography (CT). However, in the emission CT such as positron and single photon CT, poor counting static which are caused by limited dosage to patients, limited counting rate capacity and limited efficiency of the imaging device, produce a statistical noise in the reconstructed image. The magnitude of the statistical noise and the spatial resolution were evaluated for various shapes of the filter used in the convolution integrals of the filtered back-projection procedure. The statistical noise was proportional to the inverse of the root of the total number of counts for any filters. The high-frequency-cut characteristic of the filter reduced the statistical noise, but increased the spatial resolution in the images. It was possible to optimize the shape of the filter for given total number of counts and required statistical noise and spatial resolution. PMID:3492733

Iida, H; Sasaki, H; Inoue, H; Kanno, I; Miura, S; Okuyama, D; Uemura, K

1986-11-01

98

Eyeglass Filters  

Science.gov (United States)

Biomedical Optical Company of America's suntiger lenses eliminate more than 99% of harmful light wavelengths. NASA derived lenses make scenes more vivid in color and also increase the wearer's visual acuity. Distant objects, even on hazy days, appear crisp and clear; mountains seem closer, glare is greatly reduced, clouds stand out. Daytime use protects the retina from bleaching in bright light, thus improving night vision. Filtering helps prevent a variety of eye disorders, in particular cataracts and age related macular degeneration.

1987-01-01

99

Traditional healers formalised?  

Science.gov (United States)

Traditional healers are the first to be called for help when illness strikes the majority of South Africans. Their communities have faith in their ability to cure or alleviate conditions managed by doctors, and much more. A visit to such practitioners' websites (they are up with the latest advertising technology!) shows that they promise help with providing more power, love, security or money, protection from evil people and spirits, enhancing one's sex life with penis enlargement and vagina tightening spells, etc. Contemplating such claims, it is easy to be dismissive of traditional healers. But in this issue of the SAMJ Nompumelelo Mbatha and colleagues1 argue that the traditional healers' regulatory council, promised by an Act of Parliament, should be established, followed by (or preferably preceded by) formal recognition by employers of sick certificates issued by traditional healers. Can matters be so simply resolved? What does this mean for doctors and other formally recognised healthcare professionals, and how to respond to such claims and social pressures? PMID:22380886

Van Niekerk, Jp

2012-03-01

100

Building on tradition  

Directory of Open Access Journals (Sweden)

Full Text Available Sheffield University has a long and distinguished tradition of research on polymeric materials and in polymer engineering. However, the University's profile in polymer research was greatly strengthened first by the appointments in 1998 of Tony Ryan and Richard Jones and by the transfer last year of seven polymer chemists, together with their research students, research associates and equipment, from Lancaster University.

John Ebdon

2001-09-01

101

Traditional Cherokee Food.  

Science.gov (United States)

A collection for children and teachers of traditional Cherokee recipes emphasizes the art, rather than the science, of cooking. The hand-printed, illustrated format is designed to communicate the feeling of Cherokee history and culture and to encourage readers to collect and add family recipes. The cookbook could be used as a starting point for…

Hendrix, Janey B.

102

Non-Traditional Wraps  

Science.gov (United States)

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

2009-01-01

103

Traditions of technology  

Energy Technology Data Exchange (ETDEWEB)

Modern technology, with about 300 years of history behind it, has become the dominant tradition by marginalizing the other traditions of technology in the West and in the rest of the world. Important roles have been played in this marginalization by the ideology of Englightenment, by the Industrial Revolution, and nineteenth and twentieth century colonialism. They have blurred the difference between science and technology, underwritten the mechanomorphic world-image and promoted the concept of a value-free, ethically unrestrained technology. However, the present crises of technological consciousness has brought to the fore alternative traditions of technology, not as ethnotechnologies from which a universal, secular, modern technology can draw lessons, but as a competing philosophies of universality which can provide correctives to the alienating, exploitative, and dehumanizing role of modern science and technology. An alternative ideology of science is needed for this as well as a new legitimacy for the traditional technosystems and their cultural environments. Such a legitimacy will have to be based on a different set of values relating to the man--nature and man--man relationships and a deeper understanding of the politics of technology in its cross-national and cross-cultural contexts.

Nandy, A.

1979-01-01

104

Machine Print Filter for Handwriting Analysis  

OpenAIRE

Existing document decomposition models fail in well separating the zone areas of printed text and handwritten text when they are close or even touching each other. This paper presents a simple and robust algorithm to filter out the printed content in a mixed document. Following the traditional bottom-up approach, the printed text candidates are extracted and detected in the connected component level. Then the relative spatial relation and windowbased filter help providing useful information t...

Chen, Siyuan; Srihari, Sargur

2006-01-01

105

Intelligent Optimize Design of LCL Filter for Three-Phase Voltage-Source PWM Rectifier  

DEFF Research Database (Denmark)

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 intelligent optimization are more effective and simple than traditional methods.

Sun, Wei; Chen, Zhe

2009-01-01

106

The tyranny of tradition.  

Science.gov (United States)

This paper narrates the cruelty enforced by tradition on the lives of women in India. It begins with the life of the author's great-grandmother Ponnamma wherein the family was rigidly patriarchal, and Brahmin values were applied. Here, women had very little say in the decisions men made, were forced in an arranged marriage before puberty, were not sent to school, and were considered unimportant. This tradition lived on in the author's grandmother Seetha and in the life of her mother Saras. However, in the story of Saras, following the death of her husband, they departed from rigid Brahmin tradition and orthodoxy. Her mother, unperturbed by the challenges she faced, consistently devised ways to cope and succeeded in changing environment. Meaningless Brahmatic rituals and prayers found no place in her life, which she approached with a cosmopolitan and humanitarian outlook. In essence, she shaped the lives of three daughters and a son, and all her grandchildren, making a success of not only her own but of all whose lives she touched. PMID:12322347

Gulati, L

1999-01-01

107

Gas filter  

International Nuclear Information System (INIS)

A nuclear reactor containment building has a vent which is normally closed by a valve or rupturable disc but opens if the pressure therein rises unduly to discharge excess gas into a manifold which opens into an array of outward-flow tubular filter elements. The elements are of sintered stainless steel and retain radioactive particles while venting the gas to atmosphere. The temperature rise experienced by elements, due to radioactive decay, is limited by spacing the elements sufficiently to allow convective cooling of their exteriors, possibly assisted by a fan or by an enclosing cooling tower. The elements can be enclosed by a rupturable shroud. (author)

108

Dependence Image Quality On The Type Of Filter And The Cut-Off Value in SPECT Reconstruction Using FBP  

Science.gov (United States)

Image reconstruction is an important part of nuclear medicare imagmg technique. Different types of image reconstruction have been used for this propose. Despite of the fact that there are new techniques of image reconstruction, still filtered back projection method is widely used due to its simplicity and speed. Since nuclear medicine images are noisy due to less available photon statistics in the acquired images, therefore using proper filter to reduce the noise with keeping the proper signal is important. Two important parameters in most filters are the cut-off frequency and (in some cases of filters) the orders of the filter function Determining the optimal cut-off frequency for use in low pass filtering is an important part of establishing an image reconstruction strategy for clinical use. In this paper we present the result of examined filters which provide the best image quality by calculation of FWHM 1 -Line source and 2-Line sources. With this result, the best filter with specific parameter for LSF and 2-line sources is selected and the results are interpreted.

Alireza, Sadremomtaz; Payvand, Taherparvar

2011-12-01

109

Proposing a New Metric for Collaborative Filtering  

Directory of Open Access Journals (Sweden)

Full Text Available The aim of a recommender system is filtering the enormous quantity of information to obtain useful information based on the user’s interest. Collaborative filtering is a technique which improves the efficiency of recommendation systems by considering the similarity between users. The similarity is based on the given rating to data by similar users. However, user’s interest may change over time. In this paper we propose an adaptive metric which considers the time in measuring the similarity of users. The experimental results show that our approach is more accurate than the traditional collaborative filtering algorithm.

Arash Bahrehmand

2011-07-01

110

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

2008-06-01

111

The application of CIC filter in NQR explosive detection system  

International Nuclear Information System (INIS)

It introduce the principle and application of CIC Digital-filter from Digital Signal Processing and Analyzing in NQR Explosive Detection System. Compared with FIR and IIR Digital-filter traditional used, CIC Digital-filter can be decimated. In NQR Explosive Detection System, Digital Receiver often adopts big over-sampling ratios. Facing requirement of high-speed processing great quantity data, CIC filter has flexible, high-efficiency, real-time advantage. CIC Digital-filter provides a favorable method for NQR signal acquiring, processing and analyzing from some kinds explosives. (authors)

112

Effect of different thickness of material filter on Tc-99m spectra and performance parameters of gamma camera  

Science.gov (United States)

This study aimed to investigate the effects of material filter technique on Tc-99m spectra and performance parameters of Philip ADAC forte dual head gamma camera. Thickness of material filter was selected on the basis of percentage attenuation of various gamma ray energies by different thicknesses of zinc material. A cylindrical source tank of NEMA single photon emission computed tomography (SPECT) Triple Line Source Phantom filled with water and Tc-99m radionuclide injected was used for spectra, uniformity and sensitivity measurements. Vinyl plastic tube was used as a line source for spatial resolution. Images for uniformity were reconstructed by filtered back projection method. Butterworth filter of order 5 and cut off frequency 0.35 cycles/cm was selected. Chang's attenuation correction method was applied by selecting 0.13/cm linear attenuation coefficient. Count rate was decreased with material filter from the compton region of Tc-99m energy spectrum, also from the photopeak region. Spatial resolution was improved. However, uniformity of tomographic image was equivocal, and system volume sensitivity was reduced by material filter. Material filter improved system's spatial resolution. Therefore, the technique may be used for phantom studies to improve the image quality.

Nazifah, A.; Norhanna, S.; Shah, S. I.; Zakaria, A.

2014-11-01

113

Enhanced 3D PET OSEM reconstruction using inter-update Metz filtering.  

Science.gov (United States)

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. PMID:10958204

Jacobson, M; Levkovitz, R; Ben-Tal, A; Thielemans, K; Spinks, T; Belluzzo, D; Pagani, E; Bettinardi, V; Gilardi, M C; Zverovich, A; Mitra, G

2000-08-01

114

Enhanced 3D PET OSEM reconstruction using inter-update Metz filtering  

Energy Technology Data Exchange (ETDEWEB)

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)

Jacobson, M.; Levkovitz, R.; Ben-Tal, A. [MINERVA Optimization Center, Technion, Haifa 32000 (Israel); Thielemans, K.; Spinks, T. [MRC CU, Hammersmith Hospital, London (United Kingdom); Belluzzo, D.; Pagani, E.; Bettinardi, V.; Gilardi, M.C. [HSR, Milan (Italy); Zverovich, A.; Mitra, G. [Department of Mathematical Sciences, Brunel University, Uxbridge (United Kingdom)

2000-08-01

115

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. mmercial reprojection algorithm software. (author)

116

A Kalman filter technique applied for medical image reconstruction  

International Nuclear Information System (INIS)

Medical images contain information about vital organic tissues inside of human body and are widely used for diagnoses of disease or for surgical purposes. Image reconstruction is essential for medical images for some applications such as suppression of noise or de-blurring the image in order to provide images with better quality and contrast. Due to vital rule of image reconstruction in medical sciences the corresponding algorithms with better efficiency and higher speed is desirable. Most algorithms in image reconstruction are operated on frequency domain such as the most popular one known as filtered back projection. In this paper we introduce a Kalman filter technique which is operated in time domain for medical image reconstruction. Results indicated that as the number of projection increases in both normal collected ray sum and the collected ray sum corrupted by noise the quality of reconstructed image becomes better in terms of contract and transparency. It is also seen that as the number of projection increases the error index decreases.

117

Application of CT filter algorithms to digitized film data  

International Nuclear Information System (INIS)

The CT studies performed thus far in the RAS division have been based on neutron radiographs of two 7-pin reactor fuel bundles which were subjected to over-power accident simulations in the TREAT reactor. As a result of the tests, the pins were severely damaged, with molten fuel and steel spreading throughout the fuel assembly. The neutron radiographs are produced at the NRAD reactor facility at ANL-West in Idaho. The RAS reconstruction codes are based on the filtered back-projection technique, using standard fast Fourier transforms and filter algorithms. Because of the length of the fuel assemblies, and the fact that they are held only at the top by the rotation mechanism, it is nearly impossible to achieve a perfect vertical alignment, so a major part of the analysis time is spent in rotating and aligning the images. As part of this computerized alignment, each image is also normalized to a constant exposure time, based on the data in a neutron absorbing step wedge that is imaged along with the fuel pins. All computer codes were loosely developed from those given in the Donner Algorithms prepared for the National Cancer Institute and are currently run on a PDP-11/60 computer

118

FPGA design of a real-time edge enhancing smoothing filter  

Science.gov (United States)

Traditional noise removal filters have an undesirable side effect of blurring edges, which is unacceptable for some image processing applications. To overcome this problem, our ongoing project evaluates an edge enhancing smoothening filter and implements it on FPGAs to reduce noise while sharpening edges. One such edge enhancing smoothing filter consists of a combination of the bilateral filter (used for edge preserving smoothing) and the Shock filter (used for edge enhancement) to achieve the desired result. This paper describes an implementation of the bilateral filter on Altera FPGAs. Shock filter part is then briefly described. Area and speed performance results for different Altera FPGA families are comparatively shown.

Pandya, Nimit; Choo, Chang

2013-02-01

119

Rapid digital filtering.  

Science.gov (United States)

Image filtering with the larger, and potentially most valuable, digital filters is very time-consuming, thus precluding use of these filters in routine clinical applications. A recently developed algorithm for spatial-domain filtering is described, and its speed is compared with those of conventional methods with and without an array processor. Using the new Chebyshev method, a 64 by 64 pixel image can be filtered on a standard 16-bit minicomputer with filters of size 3 by 3 to 23 by 23 in 1.4-9.2 sec. The conventional spatial-domain algorithm requires 3.8-71 sec. With an array processor, filtering is accomplished in 0.19-0.54 sec. Filtering in the frequency domain requires 34 sec without an array processor and 0.12 sec with one. Thus with this new Chebyshev algorithm, clinically practical digital filtering can be performed with large filters even without an array processor. PMID:6864316

Miller, T R; Sampathkumaran, K S; King, M A

1983-07-01

120

Rapid digital filtering  

International Nuclear Information System (INIS)

Image filtering with the larger, and potentially most valuable, digital filters is very time-consuming, thus precluding use of these filters in routine clinical applications. A recently developed algorithm for spatial-domain filtering is described, and its speed is compared with those of conventional methods with and without an array processor. Using the new Chebyshev method, a 64 by 64 pixel image can be filtered on a standard 16-bit minicomputer with filters of size 3 by 3 to 23 by 23 in 1.4 to 9.2 sec. The conventional spatial-domain algorithm requires 3.8 to 71 sec. With an array processor, filtering is accomplished in 0.19 to 0.54 sec. Filtering in the frequency domain requires 34 sec without an array processor and 0.12 sec with one. Thus with this new Chebyshev algorithm, clinically practical digital filtering can be performed with large filters even without an array processor

121

The use of filtering methods to compensate for constant attenuation in single-photon emission computed tomography  

International Nuclear Information System (INIS)

A back projection of filtered projection (BKFIL) reconstruction algorithm is presented that is applicable to single-photon emission computed tomography (ECT) in the presence of a constant attenuating medium such as the brain. The filters used in transmission computed tomography (TCT)-comprised of a ramp multiplied by window functions-are modified so that the single-photon ECT filter is a function of the constant attenuation coefficient. The filters give good reconstruction results with sufficient angular and lateral sampling. With continuous samples the BKFIL algorithm has a point spread function that is the Hankel transform of the window function. The resolution and statistical properties of the filters are demonstrated by various simulations which assume an ideal detector response. Statistical formulas for the reconstructed image show that the square of the percent-root-mean-square (percent-rms) uncertainty of the reconstruction is inversely proportional to the total measured counts. The results indicate that constant attenuation can be compensated for by using an attenuation-dependent filter that reconstructs the transverse section reliably. Computer time requirements are two times that of conventional TCT or positron ECT and there is no increase in memory requirements

122

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

2011-10-01

123

Application of Moving Object Tracking Based on Kalman Filter Algorithm  

OpenAIRE

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

2013-01-01

124

Property Rights And Traditional Knowledge  

OpenAIRE

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...

Jt, Cross

2010-01-01

125

Reception of the Istrian musical tradition(s  

Directory of Open Access Journals (Sweden)

Full Text Available 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

2007-01-01

126

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

2013-01-01

127

Compact Microstrip Spurline Bandstop Filter with Defected Ground Structure (Dgs  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents a new structure to implement compact narrowband high-rejection microstrip band-stop filter (BSF. This structure is the combination of two traditional BSFs: Spurline filter and BSF using defected ground structure (DGS. Due to inherently compact characteristics of both Spurline and interdigital capacitance (used as DGS, the proposed filter shows a better rejection performance than Spurline filter and open stub conventional BSF without increasing the circuit size. From, the proposed BSF has a rejection of better than 20dB and the maximum rejection level of 41dB.

Abhijeet Kumar

2014-08-01

128

HEPA Filter Vulnerability Assessment  

International Nuclear Information System (INIS)

This assessment of High Efficiency Particulate Air (HEPA) filter vulnerability was requested by the USDOE Office of River Protection (ORP) to satisfy a DOE-HQ directive to evaluate the effect of filter degradation on the facility authorization basis assumptions. Within the scope of this assessment are ventilation system HEPA filters that are classified as Safety-Class (SC) or Safety-Significant (SS) components that perform an accident mitigation function. The objective of the assessment is to verify whether HEPA filters that perform a safety function during an accident are likely to perform as intended to limit release of hazardous or radioactive materials, considering factors that could degrade the filters. Filter degradation factors considered include aging, wetting of filters, exposure to high temperature, exposure to corrosive or reactive chemicals, and exposure to radiation. Screening and evaluation criteria were developed by a site-wide group of HVAC engineers and HEPA filter experts from published empirical data. For River Protection Project (RPP) filters, the only degradation factor that exceeded the screening threshold was for filter aging. Subsequent evaluation of the effect of filter aging on the filter strength was conducted, and the results were compared with required performance to meet the conditions assumed in the RPP Authorization Basis (AB). It was found that the reduction in filter strength due to aging does not affect the filter performance requirements as specified in the AB. A portion of the HEPA filter vulnerability assessment is being conducted by the ORP and is not part of the scope of this study. The ORP is conducting an assessment of the existing policies and programs relating to maintenance, testing, and change-out of HEPA filters used for SC/SS service. This document presents the results of a HEPA filter vulnerability assessment conducted for the River protection project as requested by the DOE Office of River Protection

129

SAW Filter Performance Improvement  

Directory of Open Access Journals (Sweden)

Full Text Available Surface acoustic wave (SAW filters have a widerange of applications, including, for example, inmobile/wireless transceivers, radio frequency (RF filters,intermediate frequency (IF filters, resonator-filters, filtersfor mobile and wireless circuits, IF filters in a basetransceiver station (BTS, RF front-end filtersfor mobile/wireless circuitry, multimode frequencyagile oscillators for spread-spectrum securecommunications, nyquist filters for microwave digitalradio, voltage controlled oscillators for first or second stagemixing in mobile transceivers, delay lines for low powertime-diversity wireless receivers, pseudo-noise-coded delaylines for combined code division multiple access/timedivision multiple access (CDMA/TDMA access, clockrecovery filters for fiber-opticscommunication repeater stages, synchronous, spreadspectrum communications, televisions, videorecorders, and many other applications. SAW filters arealso finding increasing use as picture-signal intermediatefrequency (PIF filters, vestigial sideband (VSB filters, andother types of communication filters, and as filters fordigital signal processing [1]. It is, however, supported and leadby various technologies of publiccommunication systems such as fiber optics, digital microwaveand satellites. Various custom SAW devices for publiccommunication systems have been already widely used andstill progress [2].This paper describes various methods to minimize some of thedistortions in SAW filter. It includes bulk wave distortion andfeed through distortion.

Monali R. Dave

2012-01-01

130

Basalt Fiber Based Filters  

International Science & Technology Center (ISTC)

Development of Highly Effective Filtering Systems on the Basis of a Super-Thin Basalt Fiber for Radioactive Aerosols Purification and Creation of a Work Cycle for Filters Manufacturig with the Purpose of Their Operation at the Nuclear Power Plants

131

Oriented Fiber Filter Media  

OpenAIRE

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 t...

Bharadwaj, R.; A Patel, S. Chokdeepanich; G G Chase, Ph D.

2008-01-01

132

Tradition?! Traditional Cultural Institutions on Customary Practices in Uganda  

OpenAIRE

This contribution traces the importance of traditional institutions in rehabilitating societies in general terms and more particularly in post-independence Uganda. The current regime, partly by inventing “traditional” cultural institutions, partly by co-opting them for its own interests, contributed to a loss of legitimacy of those who claim responsibility for customary law. More recently, international prosecutions have complicated the use of customary mechanisms within such societies. T...

Quinn The University Of Western Ontario, Joanna R.

2014-01-01

133

Filter service system  

Science.gov (United States)

According to an exemplary embodiment of the present disclosure, a system for removing matter from a filtering device includes a gas pressurization assembly. An element of the assembly is removably attachable to a first orifice of the filtering device. The system also includes a vacuum source fluidly connected to a second orifice of the filtering device.

Sellers, Cheryl L. (Peoria, IL); Nordyke, Daniel S. (Arlington Heights, IL); Crandell, Richard A. (Morton, IL); Tomlins, Gregory (Peoria, IL); Fei, Dong (Peoria, IL); Panov, Alexander (Dunlap, IL); Lane, William H. (Chillicothe, IL); Habeger, Craig F. (Chillicothe, IL)

2008-12-09

134

Nonlinear Attitude Filtering Methods  

Science.gov (United States)

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

2005-01-01

135

Filtering, FDR and power  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background In high-dimensional data analysis such as differential gene expression analysis, people often use filtering methods like fold-change or variance filters in an attempt to reduce the multiple testing penalty and improve power. However, filtering may introduce a bias on the multiple testing correction. The precise amount of bias depends on many quantities, such as fraction of probes filtered out, filter statistic and test statistic used. Results We show that a biased multiple testing correction results if non-differentially expressed probes are not filtered out with equal probability from the entire range of p-values. We illustrate our results using both a simulation study and an experimental dataset, where the FDR is shown to be biased mostly by filters that are associated with the hypothesis being tested, such as the fold change. Filters that induce little bias on the FDR yield less additional power of detecting differentially expressed genes. Finally, we propose a statistical test that can be used in practice to determine whether any chosen filter introduces bias on the FDR estimate used, given a general experimental setup. Conclusions Filtering out of probes must be used with care as it may bias the multiple testing correction. Researchers can use our test for FDR bias to guide their choice of filter and amount of filtering in practice.

van Iterson Maarten

2010-09-01

136

Aurorae in Australian Aboriginal Traditions  

Science.gov (United States)

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.

2013-07-01

137

Aurorae in Australian Aboriginal Traditions  

CERN Document Server

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

2013-01-01

138

FPGA Based Kalman Filter for Wireless Sensor Networks  

Directory of Open Access Journals (Sweden)

Full Text Available A Wireless Sensor Network (WSN is a set of tiny and low-cost devices equipped with different kind of sensors, a small microcontroller and a radio transceiver, typically powered by batteries. Target tracking is one of the very important applications of such a network system. Traditionally, KF (Kalman filtering and its derivatives are used for tracking of a random signal. Kalman filter is a linear optimal filtering approach, to address the problem when system dynamics become nonlinear, researchers developed sub-optimal extensions of Kalman filter, two popular versions are EKF (extended Kalman filter and UKF (unscented Kalman filter.The rapidly increasing popularity of WSNs has placed increased computational demands upon these systemswhich can be met by FPGA based design. FPGAs offer increased performance compared to microprocessors and increased flexibility compared to ASICs , while maintaining low power consumption

Vikrant Vij

2011-01-01

139

Applicapability of Traditional Ceramic for Water Treatment in Small Communities  

Directory of Open Access Journals (Sweden)

Full Text Available 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 measured before and after filtration through a ceramic pipe wall. We used ceramic pipes made of clay (with 90% purity. It turned out that ceramic filters are capable of eliminating indicator microorganisms and turbidity to a considerable degree. They can also remove 70% of the waters color. But this system could not eliminate Dissolved Solids, Electrical Conductivity, Hardness and the Nitrate ion content of water. Using Mann-Withney U Test and T- Test, it is confirmed that increasing the thickness and number of ceramic pipes is not effective for improving some water parameters. This research showed ceramic filters can be useful for household water treatment in places where there is microbial pollution or high turbidity.

K Naddafi

2005-08-01

140

Bibliography on African Traditional Religion  

Science.gov (United States)

Compiled by Chidi Denis Isizoh, this bibliography contains books, journal articles, and selections from larger works that focus on traditional religions in Africa. Citations include items in French and German as well as English.

Isizoh, Chidi D.

1998-01-01

141

Rotationally invariant correlation filtering  

International Nuclear Information System (INIS)

A method is presented for analyzing and designing optical correlation filters that have tailored rotational invariance properties. The concept of a correlation of an image with a rotation of itself is introduced. A unified theory of rotation-invariant filtering is then formulated. The unified approach describes matched filters (with no rotation invariance) and circular-harmonic filters (with full rotation invariance) as special cases. The continuum of intermediate cases is described in terms of a cyclic convolution operation over angle. The angular filtering approach allows an exact choice for the continuous trade-off between loss of the correlation energy (or specificity regarding the image) and the amount of rotational invariance desired

142

Compact planar microwave blocking filters  

Science.gov (United States)

A compact planar microwave blocking filter includes a dielectric substrate and a plurality of filter unit elements disposed on the substrate. The filter unit elements are interconnected in a symmetrical series cascade with filter unit elements being organized in the series based on physical size. In the filter, a first filter unit element of the plurality of filter unit elements includes a low impedance open-ended line configured to reduce the shunt capacitance of the filter.

U-Yen, Kongpop (Inventor); Wollack, Edward J. (Inventor)

2012-01-01

143

Experimental validation of a single shaped filter approach for CT using variable source-to-filter distance for examination of arbitrary object diameters.  

Science.gov (United States)

The purpose of this study was to validate the use of a single shaped filter (SF) for computed tomography (CT) using variable source-to-filter distance (SFD) for the examination of different object diameters.A SF was designed by performing simulations with the purpose of achieving noise homogeneity in the reconstructed volume and dose reduction for arbitrary phantom diameters. This was accomplished by using a filter design method thats target is to achieve a homogeneous detector noise, but also uses a correction factor for the filtered back projection process. According to simulation results, a single SF designed for one of the largest phantom diameters meets the requirements for all diameters when SFD can be adjusted. To validate these results, a SF made of aluminium alloy was manufactured. Measurements were performed on a CT scanner with polymethyl methacrylate (PMMA) phantoms of diameters from 40-100?mm. The filter was positioned at SFDs ranging from 97-168?mm depending on the phantom diameter. Image quality was evaluated for the reconstructed volume by assessing CT value accuracy, noise homogeneity, contrast-to-noise ratio weighted by dose (CNRD) and spatial resolution. Furthermore, scatter distribution was determined with the use of a beam-stop phantom. Dose was measured for a PMMA phantom with a diameter of 100?mm using a calibrated ionization chamber.The application of a single SF at variable SFD led to improved noise uniformity and dose reduction: noise homogeneity was improved from 15% down to about 0%, and dose was reduced by about 37%. Furthermore, scatter dropped by about 32%, which led to reduced cupping artifacts and improved CT value accuracy. Spatial resolution and CNRD was not affected by the SF.By means of a single SF with variable SFD designed for CT, significant dose reduction can be achieved and image quality can be improved by reducing noise inhomogeneity as well as scatter-induced artifacts. PMID:25198916

Lück, Ferdinand; Kolditz, Daniel; Hupfer, Martin; Steiding, Christian; Kalender, Willi A

2014-10-01

144

Experimental validation of a single shaped filter approach for CT using variable source-to-filter distance for examination of arbitrary object diameters  

Science.gov (United States)

The purpose of this study was to validate the use of a single shaped filter (SF) for computed tomography (CT) using variable source-to-filter distance (SFD) for the examination of different object diameters. A SF was designed by performing simulations with the purpose of achieving noise homogeneity in the reconstructed volume and dose reduction for arbitrary phantom diameters. This was accomplished by using a filter design method thats target is to achieve a homogeneous detector noise, but also uses a correction factor for the filtered back projection process. According to simulation results, a single SF designed for one of the largest phantom diameters meets the requirements for all diameters when SFD can be adjusted. To validate these results, a SF made of aluminium alloy was manufactured. Measurements were performed on a CT scanner with polymethyl methacrylate (PMMA) phantoms of diameters from 40-100?mm. The filter was positioned at SFDs ranging from 97-168?mm depending on the phantom diameter. Image quality was evaluated for the reconstructed volume by assessing CT value accuracy, noise homogeneity, contrast-to-noise ratio weighted by dose (CNRD) and spatial resolution. Furthermore, scatter distribution was determined with the use of a beam-stop phantom. Dose was measured for a PMMA phantom with a diameter of 100?mm using a calibrated ionization chamber. The application of a single SF at variable SFD led to improved noise uniformity and dose reduction: noise homogeneity was improved from 15% down to about 0%, and dose was reduced by about 37%. Furthermore, scatter dropped by about 32%, which led to reduced cupping artifacts and improved CT value accuracy. Spatial resolution and CNRD was not affected by the SF. By means of a single SF with variable SFD designed for CT, significant dose reduction can be achieved and image quality can be improved by reducing noise inhomogeneity as well as scatter-induced artifacts.

Lück, Ferdinand; Kolditz, Daniel; Hupfer, Martin; Steiding, Christian; Kalender, Willi A.

2014-10-01

145

Ceramic fiber filter technology  

Energy Technology Data Exchange (ETDEWEB)

Fibrous filters have been used for centuries to protect individuals from dust, disease, smoke, and other gases or particulates. In the 1970s and 1980s ceramic filters were developed for filtration of hot exhaust gases from diesel engines. Tubular, or candle, filters have been made to remove particles from gases in pressurized fluidized-bed combustion and gasification-combined-cycle power plants. Very efficient filtration is necessary in power plants to protect the turbine blades. The limited lifespan of ceramic candle filters has been a major obstacle in their development. The present work is focused on forming fibrous ceramic filters using a papermaking technique. These filters are highly porous and therefore very lightweight. The papermaking process consists of filtering a slurry of ceramic fibers through a steel screen to form paper. Papermaking and the selection of materials will be discussed, as well as preliminary results describing the geometry of papers and relative strengths.

Holmes, B.L.; Janney, M.A.

1996-06-01

146

Exhaust gas filter  

International Nuclear Information System (INIS)

A filter material formed by joining glass clothes to both surfaces of a glass fiber non-woven fabric is used. The filter material is disposed at the inside of a square filter material support frame made of stainless steel. The filter material is attached in a zig-zag manner in the flowing direction of the exhaust gases so as to increase the filtration area. Separators, for example, made of stainless steel are inserted between the filter materials. The separator is corrugated so as to sandwich and support the filter materials from both sides by the ridged crests. The longitudinal bottom of the separator formed by corrugating it defines a flow channel of the exhaustion gases. The longitudinal bottom is also used as a channel for back blowing air. With such a constitution, combustion gases of radioactive miscellaneous solid wastes can be completely filtered. In addition, a back wash can be conducted under high temperature. (I.N.)

147

Adaptive spatio-temporal filtering of multichannel surface EMG signals.  

Science.gov (United States)

A motor unit (MU) is defined as an anterior horn cell, its axon, and the muscle fibres innervated by the motor neuron. A surface electromyogram (EMG) is a superposition of many different MU action potentials (MUAPs) generated by active MUs. The objectives of this study were to introduce a new adaptive spatio-temporal filter, here called maximum kurtosis filter (MKF), and to compare it with existing filters, on its performance to detect a single MUAP train from multichannel surface EMG signals. The MKF adaptively chooses the filter coefficients by maximising the kurtosis of the output. The proposed method was compared with five commonly used spatial filters, the weighted low-pass differential filter (WLPD) and the marginal distribution of a continuous wavelet transform. The performance was evaluated using simulated EMG signals. In addition, results from a multichannel surface EMG measurement fro from a subject who had been previously exposed to radiation due to cancer were used to demonstrate an application of the method. With five time lags of the MKF, the sensitivity was 98.7% and the highest sensitivity of the traditional filters was 86.8%, which was obtained with the WLPD. The positive predictivities of these filters were 87.4 and 80.4%, respectively. Results from simulations showed that the proposed spatio-temporal filtration technique significantly improved performance as compared with existing filters, and the sensitivity and the positive predictivity increased with an increase in number of time lags in the filter. PMID:16937162

Ostlund, Nils; Yu, Jun; Karlsson, J Stefan

2006-03-01

148

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

2012-01-01

149

Fast anisotropic Gauss filtering.  

Science.gov (United States)

We derive the decomposition of the anisotropic Gaussian in a one-dimensional (1-D) Gauss filter in the x-direction followed by a 1-D filter in a nonorthogonal direction phi. So also the anisotropic Gaussian can be decomposed by dimension. This appears to be extremely efficient from a computing perspective. An implementation scheme for normal convolution and for recursive filtering is proposed. Also directed derivative filters are demonstrated. For the recursive implementation, filtering an 512 x 512 image is performed within 40 msec on a current state of the art PC, gaining over 3 times in performance for a typical filter, independent of the standard deviations and orientation of the filter. Accuracy of the filters is still reasonable when compared to truncation error or recursive approximation error. The anisotropic Gaussian filtering method allows fast calculation of edge and ridge maps, with high spatial and angular accuracy. For tracking applications, the normal anisotropic convolution scheme is more advantageous, with applications in the detection of dashed lines in engineering drawings. The recursive implementation is more attractive in feature detection applications, for instance in affine invariant edge and ridge detection in computer vision. The proposed computational filtering method enables the practical applicability of orientation scale-space analysis. PMID:18237967

Geusebroek, Jan-Mark; Smeulders, Arnold W M; van de Weijer, Joost

2003-01-01

150

Denoising Jet Engine Gas Path Measurements Using Nonlinear Filters  

OpenAIRE

Traditionally, linear filters have been used to smooth time series of gas path measurements before performing fault detection and isolation. However, linear filters can smooth out sharp trend shifts in the signal and are also not good at removing outliers. Since most fault detection and isolation algorithms are optimized for Gaussian noise, they can show performance degradation when outliers are present. In this study, numerical results with simulated data for engine deterioration and abrupt ...

Verma, Rajeev; Ganguli, Ranjan

2005-01-01

151

Spatial filtering efficiency of monostatic biaxial lidar: analysis and applications  

OpenAIRE

Results of lidar modeling based on spatial-angular filtering efficiency criteria are presented. Their analysis shows that the low spatial-angular filtering efficiency of traditional visible and near-infrared systems is an important cause of low signal background-radiation ratio SBR at the photodetector input. The low SBR may be responsible for considerable measurement errors and ensuing the low accuracy of the retrieval of atmospheric optical parameters. As shown, the most effec...

Agishev, Ravil R.; Comero?n Tejero, Adolfo

2002-01-01

152

Generic Kalman Filter Software  

Science.gov (United States)

The Generic Kalman Filter (GKF) software provides a standard basis for the development of application-specific Kalman-filter programs. Historically, Kalman filters have been implemented by customized programs that must be written, coded, and debugged anew for each unique application, then tested and tuned with simulated or actual measurement data. Total development times for typical Kalman-filter application programs have ranged from months to weeks. The GKF software can simplify the development process and reduce the development time by eliminating the need to re-create the fundamental implementation of the Kalman filter for each new application. The GKF software is written in the ANSI C programming language. It contains a generic Kalman-filter-development directory that, in turn, contains a code for a generic Kalman filter function; more specifically, it contains a generically designed and generically coded implementation of linear, linearized, and extended Kalman filtering algorithms, including algorithms for state- and covariance-update and -propagation functions. The mathematical theory that underlies the algorithms is well known and has been reported extensively in the open technical literature. Also contained in the directory are a header file that defines generic Kalman-filter data structures and prototype functions and template versions of application-specific subfunction and calling navigation/estimation routine code and headers. Once the user has provided a calling routine and the required application-specific subfunctions, the application-specific Kalman-filter software can be compiled and executed immediately. During execution, the generic Kalman-filter function is called from a higher-level navigation or estimation routine that preprocesses measurement data and post-processes output data. The generic Kalman-filter function uses the aforementioned data structures and five implementation- specific subfunctions, which have been developed by the user on the basis of the aforementioned templates. The GKF software can be used to develop many different types of unfactorized Kalman filters. A developer can choose to implement either a linearized or an extended Kalman filter algorithm, without having to modify the GKF software. Control dynamics can be taken into account or neglected in the filter-dynamics model. Filter programs developed by use of the GKF software can be made to propagate equations of motion for linear or nonlinear dynamical systems that are deterministic or stochastic. In addition, filter programs can be made to operate in user-selectable "covariance analysis" and "propagation-only" modes that are useful in design and development stages.

Lisano, Michael E., II; Crues, Edwin Z.

2005-01-01

153

Tunepal: the Traditional Musician's Toolbox  

OpenAIRE

In this paper we present Tunepal, a search engine and music retrieval tool for traditional musicians that runs on an iPhone/iPod Touch (2nd generation)/iPad. Tunepal connects musicians the scores and metadata of 13,290 traditional Irish, Welsh, Scottish and Breton dance tunes. These tunes are drawn from community sources, such as the website thesession.org and “standard” references including O’Neills Dance Music of Ireland and Brendan Breathneach’s Ceol Rince Na hÉireann series. Tune...

Duggan, Bryan

2010-01-01

154

Traditional healers and cancer prevention  

Directory of Open Access Journals (Sweden)

Full Text Available The increase in the incidence of cancer in South Africa necessitates the expansion of preventative efforts. This study shows that traditional healers in Atteridgeville are consulted by a range of people in their communities, have a basic knowledge of cancer, provide health education to their patients and are willing to participate in cancer preventative strategies. They are therefore ideally suited to augment the services of westernized health care workers. The issue of professionalization is explored and a procedure is suggested whereby the training of traditional healers can be enhanced so as to facilitate their professionalization and their collaboration with other health care workers in the prevention of cancer.

M Steyn

2000-09-01

155

Morphing Ensemble Kalman Filters  

OpenAIRE

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 automati...

Beezley, Jonathan D.; Mandel, Jan

2007-01-01

156

Configurable Multirate Filter Banks  

OpenAIRE

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

2008-01-01

157

Cryogenic coaxial microwave filters  

OpenAIRE

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 curren...

Tancredi, G.; Schmidlin, S.; Meeson, P. J.

2013-01-01

158

Hybrid Filter Membrane  

Science.gov (United States)

Cabin environmental control is an important issue for a successful Moon mission. Due to the unique environment of the Moon, lunar dust control is one of the main problems that significantly diminishes the air quality inside spacecraft cabins. Therefore, this innovation was motivated by NASA s need to minimize the negative health impact that air-suspended lunar dust particles have on astronauts in spacecraft cabins. It is based on fabrication of a hybrid filter comprising nanofiber nonwoven layers coated on porous polymer membranes with uniform cylindrical pores. This design results in a high-efficiency gas particulate filter with low pressure drop and the ability to be easily regenerated to restore filtration performance. A hybrid filter was developed consisting of a porous membrane with uniform, micron-sized, cylindrical pore channels coated with a thin nanofiber layer. Compared to conventional filter media such as a high-efficiency particulate air (HEPA) filter, this filter is designed to provide high particle efficiency, low pressure drop, and the ability to be regenerated. These membranes have well-defined micron-sized pores and can be used independently as air filters with discreet particle size cut-off, or coated with nanofiber layers for filtration of ultrafine nanoscale particles. The filter consists of a thin design intended to facilitate filter regeneration by localized air pulsing. The two main features of this invention are the concept of combining a micro-engineered straight-pore membrane with nanofibers. The micro-engineered straight pore membrane can be prepared with extremely high precision. Because the resulting membrane pores are straight and not tortuous like those found in conventional filters, the pressure drop across the filter is significantly reduced. The nanofiber layer is applied as a very thin coating to enhance filtration efficiency for fine nanoscale particles. Additionally, the thin nanofiber coating is designed to promote capture of dust particles on the filter surface and to facilitate dust removal with pulse or back airflow.

Laicer, Castro; Rasimick, Brian; Green, Zachary

2012-01-01

159

Morphological bilateral filtering  

OpenAIRE

A current challenging topic in mathematical morphology is the construction of locally adaptive operators; i.e., structuring functions that are dependent on the input image itself at each position. Development of spatially-variant filtering is well established in the theory and practice of Gaussian filtering. The aim of the first part of the paper is to study how to generalize these convolution-based approaches in order to introduce adaptive nonlinear filters that asymptotically correspond to ...

Angulo, Jesus

2013-01-01

160

Oriented Fiber Filter Media  

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

2008-06-01

161

Approximate Kalman filtering  

CERN Document Server

Kalman filtering algorithm gives optimal (linear, unbiased and minimum error-variance) estimates of the unknown state vectors of a linear dynamic-observation system, under the regular conditions such as perfect data information; complete noise statistics; exact linear modeling; ideal well-conditioned matrices in computation and strictly centralized filtering.In practice, however, one or more of the aforementioned conditions may not be satisfied, so that the standard Kalman filtering algorithm cannot be directly used, and hence "approximate Kalman filtering" becomes necessary. In the last decad

Chen, G

1993-01-01

162

Filters in nuclear facilities  

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.)

163

Paul Rodgersi filter Kohilas  

Index Scriptorium Estoniae

28. I Kohila keskkoolis kohaspetsiifiline skulptuur ja performance "Filter". Kooli 130. aastapäeva tähistava ettevõtmise eesotsas oli skulptor Paul Rodgers ja kaks viimase klassi noormeest ? Marko Heinmäe, Hendrik Karm.

2000-01-01

164

Filter holder and gasket assembly for candle or tube filters  

Energy Technology Data Exchange (ETDEWEB)

A filter holder and gasket assembly are disclosed for holding a candle filter element within a hot gas cleanup system pressure vessel. The filter holder and gasket assembly includes a filter housing, an annular spacer ring securely attached within the filter housing, a gasket sock, a top gasket, a middle gasket and a cast nut. 9 figs.

Lippert, T.E.; Alvin, M.A.; Bruck, G.J.; Smeltzer, E.E.

1999-03-02

165

Cosine Modulated Non-Uniform Filter Banks  

Directory of Open Access Journals (Sweden)

Full Text Available Traditional designs for non-uniform filter bank (NUFB are usually complex; involve complicated nonlinear optimization with a large number of parameters and lack of linear phase ([LP property. In this paper, we describe a simple design method for multirate near perfect reconstruction (NPR cosine modulated filter banks with non-uniform frequency spacing and linear phase property that involves optimization of only single parameter. It is derived from the uniform cosine modulated filter bank (CMFB by merging some relevant band pass filters. The design procedure and the structure of the uniform CMFB are mostly preserved in the non-uniform implementation. Compared to other design methods our method provides very good design and converges very rapidly but the method is applicable, only if the upper band edge frequency of each non-uniform filter is an integral multiple of the bandwidth of the corresponding band. The design examples are presented to show the superiority of the proposed method over existing one.

Jyotsna Ogale

2011-08-01

166

Individualizing in Traditional Classroom Settings.  

Science.gov (United States)

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.

1980-01-01

167

Traditional Teacher Education Still Matters  

Science.gov (United States)

Fresh from teaching his first full school year the author reflects on his traditional teacher preparation path into the classroom and finds he was instilled with a common sense of ethics, compassion, a demand for reflective practice, and a robust guiding philosophy. As a college student, he learned theory and was able to augment that with…

Jacobs, Nick

2013-01-01

168

Restored Behavior and Oral Traditions.  

Science.gov (United States)

Interest in oral traditions has benefitted the field of interpretation in two ways: a new emphasis on the social and cultural contexts of performance, and an expanded perspective on performance manifestations. In Richard Schechner's concept of "restored behavior," the interpreter engages in a reconstruction of living behavior independent of its…

Miranda, Kathleen Bindert

169

Editorial: Between Tradition and Modernity  

OpenAIRE

The relationship between religious ‘tradition’ and ‘modernity’ is a central theme in various academic debates. Of the heatedly debated topic is concerning religious identity in the face of constantly political, economical, and global changes. As with other religious communities, Muslims have to response to these changes, on the one hand, and to the call for preserving their religious identity, on the other. 

Editor Al-Jami'ah: Journal of Islamic Studies

2011-01-01

170

Root-Raised Cosine Filter Implementation That Uses Canonical Signed Digits for High-Speed Digital Filter Applications  

Science.gov (United States)

NASA Lewis Research Center's Space Communications Division has been investigating high-speed digital filters that can operate at a higher speed than those in current use for a digital modulator and demodulator (modem). Using the Canonical Signed Digits (CSD) number representation for filter coefficients is a very effective way to increase the filter's speed while reducing complexity in the digital filter hardware design. This approach is a good alternative to using an expensive parallel-processing design technique or custom, application-specific integrated circuits. Such integrated circuits may not be suitable for applications that require filter speeds faster than what application-specific integrated circuits digital signal processors can offer for a dedicated channel. When a communication channel is a dedicated, multiplication process--a costly, time-consuming process--it can be greatly simplified by a replacement of the filter coefficients with CSD numbers. A computer code written with the MATLAB software package runs the program and generates CSD-represented filter coefficients that are based on minimizing minimum mean square errors. Also, the Alta Group of Cadence's Signal Processing Workstation is used to simulate and analyze the CSD filter responses. The impulse response of the root-raised cosine filter that is used as a base model is defined. From this filter, a set of coefficients is sampled and stored in a file. For the all coefficients, the optimal CSD number for each coefficient is searched on the basis of the minimum-mean-square-errors criterion. Because the distribution of CSD numbers is not uniform, quantization errors tend to be bigger for coefficients greater than 1/2. To offset errors that occur in a region of coefficients between 1/2 to 1 and to better represent fractions with CSD numbers, an extra nonzero digit is allowed for any coefficients exceeding 1/2. This will greatly improve frequency response as well as intersymbol interference at the receiver. The frequency response of a set of collected CSD-represented filter coefficients was compared with the same filter that was conventionally implemented. Analyses show CSD-implemented filters perform as well as conventional filters. Comparison of eye diagrams and bit-error-rate curves between CSD filters and traditionally implemented filters are almost indistinguishable. However, filter complexity was reduced from almost 3.5 to 1 for CSD filters. Complete computer simulation results are available. In the near future, work will focus on building actual working digital filter hardware in a field programmable gate array (FPGA).

Kim, Heechul

1997-01-01

171

Property Rights And Traditional Knowledge  

Directory of Open Access Journals (Sweden)

Full Text Available 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 granting property rights in intangibles like inventions and expressive works. Intellectual property is meant to encourage innovation and creative activity. Most traditional knowledge, by contrast, is not innovative, at least in the same sense as the inventions and works that qualify for patents and copyrights. At present, the "anti-property" camp seems to have the better of the argument, as even the World Intellectual Property Organisation has abandoned the notion of true property rights. This article seeks to refute this philosophical objection to a property model for traditional knowledge. It argues that the classic philosophical argument justifying intellectual "property" namely, that property rights are justified only as a way to spur innovation and other creative activity is incorrect in two ways. First, the argument misstates the main goal of an intellectual property system. While intellectual property may serve as an incentive for innovation, society's primary concern is not the innovation per se, but instead the dissemination of knowledge. Second, there may be policy reasons other than the development of knowledge that can justify intellectual property-like rights. The article then applies these observations to the particular question of traditional knowledge and cultural expression. It demonstrates that a system of property rights could be useful in helping to encourage the dissemination of traditional knowledge, even if that knowledge is not "new" in the classic sense. Second, other important social concerns, especially the goal of ensuring accuracy in knowledge, may justify a system of property rights. While these arguments may not ultimately support a property rights system—after all, the practical concerns remain very real—they do help to refute the underlying philosophical objection.

JT Cross

2010-12-01

172

Property rights and traditional knowledge  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english 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 practica [...] l. 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 granting property rights in intangibles like inventions and expressive works. Intellectual property is meant to encourage innovation and creative activity. Most traditional knowledge, by contrast, is not innovative, at least in the same sense as the inventions and works that qualify for patents and copyrights. At present, the "anti-property" camp seems to have the better of the argument, as even the World Intellectual Property Organisation has abandoned the notion of true property rights. This article seeks to refute this philosophical objection to a property model for traditional knowledge. It argues that the classic philosophical argument justifying intellectual "property" namely, that property rights are justified only as a way to spur innovation and other creative activity is incorrect in two ways. First, the argument misstates the main goal of an intellectual property system. While intellectual property may serve as an incentive for innovation, society's primary concern is not the innovation per se, but instead the dissemination of knowledge. Second, there may be policy reasons other than the development of knowledge that can justify intellectual property-like rights. The article then applies these observations to the particular question of traditional knowledge and cultural expression. It demonstrates that a system of property rights could be useful in helping to encourage the dissemination of traditional knowledge, even if that knowledge is not "new" in the classic sense. Second, other important social concerns, especially the goal of ensuring accuracy in knowledge, may justify a system of property rights. While these arguments may not ultimately support a property rights system-after all, the practical concerns remain very real-they do help to refute the underlying philosophical objection.

JT, Cross.

173

An Adaptive Weighted Filter Algorithm for Mixed Noise Image  

Directory of Open Access Journals (Sweden)

Full Text Available Image de-noising by using the filter algorithm is a basic problem which we would meet during the image processing. But the traditional filters can’t achieve good effects. So a new adaptive weighted filter which could deal with the mixed noise was proposed and the weight values can be adaptively adjusted according to the differences between the reference value and the objective value of all elements in the window based on the MTM (Modified Trimmed Mean and grey relational analysis. It is shown that the new filter algorithm can preserve image detail information well and effectively remove the noise. Finally, Extensive simulations are carried out to evaluate the performance of the filter. Simulation experiments show that the new method exhibits better performance than other de-noising schemes obviously, both in the PSNR value, MSE value and the visual appearance.

Huang Chun-Yan

2013-01-01

174

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

2013-10-01

175

Filter Paper: Solution to High Self-Attenuation Corrections in HEPA Filter Measurements  

Energy Technology Data Exchange (ETDEWEB)

An 8 by 8 by 6 inch High Efficiency Particulate Air (HEPA) filter was measured as part of a uranium holdup survey in June of 2005 as it has been routinely measured every two months since 1998. Although the survey relies on gross gamma count measurements, this was one of a few measurements that had been converted to a quantitative measurement in 1998. The measurement was analyzed using the traditional Generalized Geometry Holdup (GGH) approach, using HMS3 software, with an area calibration and self-attenuation corrected with an empirical correction factor of 1.06. A result of 172 grams of {sup 235}U was reported. The actual quantity of {sup 235}U in the filter was approximately 1700g. Because of this unusually large discrepancy, the measurement of HEPA filters will be discussed. Various techniques for measuring HEPA filters will be described using the measurement of a 24 by 24 by 12 inch HEPA filter as an example. A new method to correct for self attenuation will be proposed for this measurement Following the discussion of the 24 by 24 by 12 inch HEPA filter, the measurement of the 8 by 8 by 6 inch will be discussed in detail.

Oberer, R.B.; Harold, N.B.; Gunn, C.A.; Brummett, M.; Chaing, L.G.

2005-10-01

176

Filter Paper: Solution to High Self-Attenuation Corrections in HEPA Filter Measurements  

International Nuclear Information System (INIS)

An 8 by 8 by 6 inch High Efficiency Particulate Air (HEPA) filter was measured as part of a uranium holdup survey in June of 2005 as it has been routinely measured every two months since 1998. Although the survey relies on gross gamma count measurements, this was one of a few measurements that had been converted to a quantitative measurement in 1998. The measurement was analyzed using the traditional Generalized Geometry Holdup (GGH) approach, using HMS3 software, with an area calibration and self-attenuation corrected with an empirical correction factor of 1.06. A result of 172 grams of 235U was reported. The actual quantity of 235U in the filter was approximately 1700g. Because of this unusually large discrepancy, the measurement of HEPA filters will be discussed. Various techniques for measuring HEPA filters will be described using the measurement of a 24 by 24 by 12 inch HEPA filter as an example. A new method to correct for self attenuation will be proposed for this measurement Following the discussion of the 24 by 24 by 12 inch HEPA filter, the measurement of the 8 by 8 by 6 inch will be discussed in detail

177

Internet Filtering in China  

OpenAIRE

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.

2003-01-01

178

Pinhole diffraction filter  

Science.gov (United States)

Multistage diffraction filter consisting of coalined series of pinholes on parallel sheets can be used as nondegradable UV filter. Beam is attenuated as each pinhole diffracts radiation in controlled manner into divergent beam, and following pinhole accepts only small part of that beam.

Woodgate, B. E.

1977-01-01

179

LCL Interface Filter Design for Shunt Active Power Filters  

OpenAIRE

This paper is focused on finding the parameters of a second order interface filter connected between the power system and the shunt active filter based on switching frequency of the active filter. Many publications on power active filters include various design methods for the interface inductive filter which take into account the injected current and its dynamic. Compared to these ones, the approach presented in this paper is oriented toward the design of the interface filter starting fro...

Dobriceanu, M.; Marin, D.; Popescu, M.; Bitoleanu, A.

2010-01-01

180

Observability and nonlinear filtering  

CERN Document Server

This paper develops a connection between the asymptotic stability of nonlinear filters and a notion of observability. We consider a general class of hidden Markov models in continuous time with compact signal state space, and call such a model observable if no two initial measures of the signal process give rise to the same law of the observation process. We demonstrate that observability implies stability of the filter, i.e., the filtered estimates become insensitive to the initial measure at large times. For the special case where the signal is a finite-state Markov process and the observations are of the white noise type, a complete (necessary and sufficient) characterization of filter stability is obtained in terms of a slightly weaker detectability condition. In addition to observability, the role of controllability in filter stability is explored. Finally, the results are partially extended to non-compact signal state spaces.

van Handel, Ramon

2007-01-01

181

Sintered composite filter  

Science.gov (United States)

A particulate filter medium formed of a sintered composite of 0.5 micron diameter quartz fibers and 2 micron diameter stainless steel fibers is described. Preferred composition is about 40 vol.% quartz and about 60 vol.% stainless steel fibers. The media is sintered at about 1100/sup 0/C to bond the stainless steel fibers into a cage network which holds the quartz fibers. High filter efficiency and low flow resistance are provided by the smaller quartz fibers. High strength is provided by the stainless steel fibers. The resulting media has a high efficiency and low pressure drop similar to the standard HEPA media, with tensile strength at least four times greater, and a maximum operating temperature of about 550/sup 0/C. The invention also includes methods to form the composite media and a HEPA filter utilizing the composite media. The filter media can be used to filter particles in both liquids and gases.

Bergman, W.

1986-05-02

182

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

2008-01-01

183

Weighted Guided Image Filtering.  

Science.gov (United States)

It is known that local filtering-based edge-preserving smoothing techniques suffer from halo artifacts. In this paper, a weighted guided image filter (WGIF) is introduced by incorporating an edge-aware weighting into an existing guided image filter (GIF) to address the problem. The WGIF inherits advantages of both global and local smoothing filters in the sense that: 1) the complexity of the WGIF is O(N) for an image with N pixels, which is same as the GIF and 2) the WGIF can avoid halo artifacts like the existing global smoothing filters. The WGIF is applied for single image detail enhancement, single image haze removal, and fusion of differently exposed images. Experimental results show that the resultant algorithms produce images with better visual quality and at the same time halo artifacts can be reduced/avoided from appearing in the final images with negligible increment on running times. PMID:25415986

Li, Zhengguo; Zheng, Jinghong; Zhu, Zijian; Yao, Wei; Wu, Shiqian

2015-01-01

184

Randomized Filtering Algorithms  

DEFF Research Database (Denmark)

Filtering every global constraint of a CPS to are consistency at every search step can be costly and solvers often compromise on either the level of consistency or the frequency at which are consistency is enforced. In this paper we propose two randomized filtering schemes for dense instances of AllDifferent and is generalization, the Global Cardinality Constraint. The first delayed filtering scheme is a Monte Carlo algorithm: its running time is superior, in the worst case, to that of enforcing are consistency after every domain event, while its filtering effectiveness is analyzed in the expected sense. The second scheme is a Las Vegas algorithm using filtering triggers: Its effectiveness is the same as enforcing are consistency after every domain event, while in the expected case it is faster by a factor of m/n, where n and m are, respectively, the number of nodes and edges in the variable-value graph.

Katriel, Irit; Van Hentenryck, Pascal

2008-01-01

185

Filter Bank Fusion Frames  

CERN Document Server

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

2010-01-01

186

LCL Interface Filter Design for Shunt Active Power Filters  

Directory of Open Access Journals (Sweden)

Full Text Available This paper is focused on finding the parameters of a second order interface filter connected between the power system and the shunt active filter based on switching frequency of the active filter. Many publications on power active filters include various design methods for the interface inductive filter which take into account the injected current and its dynamic. Compared to these ones, the approach presented in this paper is oriented toward the design of the interface filter starting from filter transfer functions by imposing the performances of the filter.

DOBRICEANU, M.

2010-08-01

187

Genetic contamination of traditional products  

OpenAIRE

Cross-pollination can be caused by birds, insects and wind. Genetically modified (GM) seeds are produced each year in a controlled environment to maintain their purity. However, pollen from the GM crop can be transferred to traditional crops. When the GM crop producers are in long-run equilibrium and buy seeds from a monopolistic seed producer, the resulting market equilibrium is identical to that when a seed monopolist produces the GM crop directly. When involuntary genetic contamination occ...

Choi, E. Kwan

2011-01-01

188

Traditional communities, multinationals and biodiversity  

OpenAIRE

The Iratapuru Sustainable Development Reserve is mainly exploited by the community of the São 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

2009-01-01

189

The Promise of Traditional Medicines  

OpenAIRE

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...

Inamdar, N. N.; Ansari, J. A.

2010-01-01

190

Augustine and the phenomenological tradition  

OpenAIRE

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

2012-01-01

191

Christian Belief and Religious Traditions  

OpenAIRE

This section of the Osica de Sus commune monograph - Puterea r?d?cinilor - The Roots Power, authors: Constantin Ro?ca - university profesor (coordinator), Ion Sîrbu - preuniversitary teacher, and Ion Paul Popescu - sociologist et al., Craiova, Editura Universitaria, 2009, emphasizes the main elements which characterize Christian belief, religious spirit and the religious feelings of the people in the commune. It underlines the religious traditions, the Christian customs and festivities an...

CONSTANTIN RO?CA

2010-01-01

192

Traditional transfusion practices are changing  

OpenAIRE

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.

2010-01-01

193

Software Development: Agile vs. Traditional  

OpenAIRE

Organizations face the need to adapt themselves to a complex business environment, in continuous change and transformation. Under these circumstances, organization agility is a key element in gaining strategic advantages and market success. Achieving and maintaining agility requires agile architectures, techniques, methods and tools, able to react in real time to change requirements. This paper proposes an incursion in the software development, from traditional to agile.

Stoica, Marian; Mircea, Marinela; Ghilic-micu, Bogdan

2013-01-01

194

Traditional healers and cancer prevention  

OpenAIRE

The increase in the incidence of cancer in South Africa necessitates the expansion of preventative efforts. This study shows that traditional healers in Atteridgeville are consulted by a range of people in their communities, have a basic knowledge of cancer, provide health education to their patients and are willing to participate in cancer preventative strategies. They are therefore ideally suited to augment the services of westernized health care workers. The issue of professionalization is...

Steyn, M.; Muller, A.

2000-01-01

195

TRADITIONAL FERMENTED FOODS OF LESOTHO  

OpenAIRE

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...

Gadaga, Tendekayi H.; Molupe Lehohla; Victor Ntuli

2013-01-01

196

Clay construction: traditions and perspectives  

OpenAIRE

Distinction or peculiarity of landscape very close connected with traditional architecture, which depends on natural recourses and building materials. Lithuania was country of wooden architecture, but also clay was in use at all times as supporting material. Clay building became popular on the end of XIX century, especially between the first and the second World War, latter was forgotten during the soviet occupation and revived after the recovered country independence. The first tide of clay ...

Andrius?yte?, Aiste?; Bertas?iu?te?, Rasa

2011-01-01

197

Derivative free filtering using Kalmtool  

DEFF Research Database (Denmark)

In this paper we present a toolbox enabling easy evaluation and comparison of different filtering algorithms. The toolbox is called Kalmtool 4 and is a set of MATLAB tools for state estimation of nonlinear systems. The toolbox contains functions for extended Kalman filtering as well as for DD1 filter and the DD2 filter. It also contains functions for Unscented Kalman filters as well as several versions of particle filters. The toolbox requires MATLAB version 7, but no additional toolboxes are required.

Bayramoglu, Enis Technical University of Denmark,

2010-01-01

198

Defueling filter test  

International Nuclear Information System (INIS)

The Three Mile Island Unit 2 Reactor (TMI-2) has sustained core damage creating a significant quantity of fine debris, which can become suspended during the planned defueling operations, and will have to be constantly removed to maintain water clarity and minimize radiation exposure. To accomplish these objectives, a Defueling Water Cleanup System (DWCS) has been designed. One of the primary components in the DWCS is a custom designed filter canister using an all stainless steel filter medium. The full scale filter canister is designed to remove suspended solids from 800 microns to 0.5 microns in size. Filter cartridges are fabricated into an element cluster to provide for a flowrate of greater than 100 gals/min. Babcock and Wilcox (B and W) under contract to GPU Nuclear Corporation has evaluated two candidate DWCS filter concepts in a 1/100 scale proof-of-principle test program at BandW's Lynchburg Research Center. The filters were challenged with simulated solids suspensions of 1400 and 140 ppm in borated water (5000 ppm boron). Test data collected includes solids loading, effluent turbidity, and differential pressure trends versus time. From the proof-of-principle test results, a full-scale filter canister was generated

199

A High Precision Selective Harmonic Compensation Scheme for Active Power Filters  

OpenAIRE

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

2009-01-01

200

Design and implementation of ultra-wideband bandpass filter with non-equiripple responses  

OpenAIRE

In this paper, a novel type of frequency responses of ultra-wideband (UWB) bandpass filter is presented. Different from the traditional Chebyshev transfer function filters, the in-band reflection lobes can be theoretically controlled and realized to be a dome-shaped envelope filtering responses. The amplitude of reflection coefficients near the band edge can be easily assigned to be lower than those near the center operating frequency, which is very important for reducing the sensitivity of m...

Gao, S.; Sun, S.

2013-01-01

201

A novel metamaterial filter with stable passband performance based on frequency selective surface  

OpenAIRE

In this paper, a novel metamaterial filter based on frequency selective surface (FSS) is proposed. Using the mode matching method, we theoretically studied the transmission performance of the structure. Results show that, by rotating its neighboring elements 90 degree, the novel filter has a better stability to angle of incidence than traditional structures for TE and TM polarization. As the incident angles vary from 0 to 50 degrees, the metamaterial filter exhibits a transmittance higher tha...

Fang, C. Y.; Gao, J. S.; Hai Liu

2014-01-01

202

????????? Chinese Traditional Culture and College Mathematics  

OpenAIRE

?????????????????????????????????????????????????????????????????????????????????????????This study unveils the connections between chinese traditional culture and college mathematics. By interpreti...

???; ???

2013-01-01

203

Fuzzy rank LUM filters.  

Science.gov (United States)

The rank information of samples is widely utilized in nonlinear signal processing algorithms. Recently developed fuzzy transformation theory introduces the concept of fuzzy ranks, which incorporates sample spread (or sample diversity) information into the sample ranking framework. Thus, the fuzzy rank reflects a sample's rank, as well as its similarity to the other sample (namely, joint rank order and spread), and can be utilized to improve the performance of the conventional rank-order-based filters. In this paper, the well-known lower-upper-middle (LUM) filters are generalized utilizing the fuzzy ranks, yielding the class of fuzzy rank LUM (F-LUM) filters. Statistical and deterministic properties of the F-LUM filters are derived, showing that the F-LUM smoothers have similar impulsive noise removal capability to the LUM smoothers, while preserving the image details better. The F-LUM sharpeners are capable of enhancing strong edges while simultaneously preserving small variations. The performance of the F-LUM filters are evaluated for the problems of image impulsive noise removal, sharpening and edge-detection preprocessing. The experimental results show that the F-LUM smoothers can achieve a better tradeoff between noise removal and detail preservation than the LUM smoothers. The F-LUM sharpeners are capable of sharpening the image edges without amplifying the noise or distorting the fine details. The joint smoothing and sharpening operation of the general F-LUM filters also showed superiority in edge detection preprocessing application. In conclusion, the simplicity and versatility of the F-LUM filters and their advantages over the conventional LUM filters are desirable in many practical applications. This also shows that utilizing fuzzy ranks in filter generalization is a promising methodology. PMID:17153940

Nie, Yao; Barner, Kenneth E

2006-12-01

204

HEPA filter jointer  

Energy Technology Data Exchange (ETDEWEB)

A HEPA filter jointer system was created to remove nitrate contaminated wood from the wooden frames of HEPA filters that are stored at the Rocky Flats Plant. A commercial jointer was chosen to remove the nitrated wood. The chips from the wood removal process are in the right form for caustic washing. The jointer was automated for safety and ease of operation. The HEPA filters are prepared for jointing by countersinking the nails with a modified air hammer. The equipment, computer program, and tests are described in this report.

Hill, D.; Martinez, H.E.

1998-02-01

205

Filters and Matrix Factorization  

OpenAIRE

We give a number of explicit matrix-algorithms for analysis/synthesis in multi-phase filtering; i.e., the operation on discrete-time signals which allow a separation into frequency-band components, one for each of the ranges of bands, say $N$, starting with low-pass, and then corresponding filtering in the other band-ranges. If there are $N$ bands, the individual filters will be combined into a single matrix action; so a representation of the combined operation on all $N$ ba...

Jorgensen, Palle; Song, Myung-sin

2014-01-01

206

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

2006-01-01

207

Application of Unscented Kalman Filter for Sonar Signal Processing  

Directory of Open Access Journals (Sweden)

Full Text Available State estimation theory is one of the best mathematical approaches to analyze variants in the states of the system or process. The state of the system is defined by a set of variables that provide a complete representation of the internal condition at any given instant of time. Filtering of Random processes is referred to as Estimation, and is a well defined statistical technique. There are two types of state estimation processes, Linear and Nonlinear. Linear estimation of a system can easily be analyzed by using Kalman Filter (KF and is used to compute the target state parameters with a priori information under noisy environment. But the traditional KF is optimal only when the model is linear and its performance is well defined under the assumptions that the system model and noise statistics are well known. Most of the state estimation problems are nonlinear, thereby limiting the practical applications of the KF. The modified KF, aka EKF, Unscented Kalman filter and Particle filter are best known for nonlinear estimates. Extended Kalman filter (EKF is the nonlinear version of the Kalman filter which linearizes about the current mean and covariance. The EKF has been considered the standard in the theory of nonlinear state estimation. Since linear systems do not really exist, a novel transformation is adopted. Unscented Kalman filter and Particle filter are best known nonlinear estimates. The approach in this paper is to analyze the algorithm for maneuvering target tracking using bearing only measurements where UKF provides better probability of state estimation.

Leela Kumari. B , Padma Raju.K

2012-06-01

208

Implementing Cepstral Filtering Technique using Gabor Filters  

OpenAIRE

Cepstral filtering technique is applied on an interlaced image, the pattern similar to that which is found in layer IV of Primate Visual Cortex. Unless the signals from left and right eyes are placed simultaneously, the disparity cannot be detected. Therefore, it has a great significance in the sphere of stereo vision. It involves Power spectrum in computation, which is square of absolute of Fast Fourier Transform (FFT), is a complicated and hardware unfriendly. This paper shows the estimatio...

Sharma, Sheena

2012-01-01

209

Adapting agriculture with traditional knowledge  

Energy Technology Data Exchange (ETDEWEB)

Over the coming decades, climate change is likely to pose a major challenge to agriculture; temperatures are rising, rainfall is becoming more variable and extreme weather is becoming a more common event. Researchers and policymakers agree that adapting agriculture to these impacts is a priority for ensuring future food security. Strategies to achieve that in practice tend to focus on modern science. But evidence, both old and new, suggests that the traditional knowledge and crop varieties of indigenous peoples and local communities could prove even more important in adapting agriculture to climate change.

Swiderska, Krystyna; Reid, Hannah [IIED, London (United Kingdom); Song, Yiching; Li, Jingsong [Centre for Chinese Agriculutral Policy (China); Mutta, Doris [Kenya Forestry Research Institute (Kenya)

2011-10-15

210

Christian Belief and Religious Traditions  

Directory of Open Access Journals (Sweden)

Full Text Available This section of the Osica de Sus commune monograph - Puterea r?d?cinilor - The Roots Power, authors: Constantin Ro?ca - university profesor (coordinator, Ion Sîrbu - preuniversitary teacher, and Ion Paul Popescu - sociologist et al., Craiova, Editura Universitaria, 2009, emphasizes the main elements which characterize Christian belief, religious spirit and the religious feelings of the people in the commune. It underlines the religious traditions, the Christian customs and festivities and presents the worship places (churches and distinct religious communities, such as the Adventist community in the commune.

CONSTANTIN RO?CA

2010-06-01

211

Throughput of NUV filters  

Science.gov (United States)

The purpose is to measure the absolute sensitivity of the NUVMAMA imaging modes with the the CN182, CN270, MGII, and CIII filters. Justification: On orbit measurements of spectrophotometric standards suggest a 10-15% drop in imaging sensitivity in the NUV relative to pre-launch estimates. This measurment is based on observations of a single star in the MGII and CIII filters, and of a different standard with the F25ND3 filter. We wish to confirm the sensitivity change and measure its wavelength dependence by observing spectrophotometric standard with the NUV narrrow and intermediate-band filters. Two different stars are required for the different bandwidths because of the bright-object limitations of the MAMA detector.

Ferguson, Harry

1997-07-01

212

Cryogenic coaxial microwave filters  

CERN Document Server

At millikelvin temperatures the careful filtering of electromagnetic radiation, especially in the microwave regime, is critical for controlling the electromagnetic environment for experiments in fields such as solid-state quantum information processing and quantum metrology. We present a design for a filter consisting of small diameter dissipative coaxial cables that is straightforward to construct and provides a quantitatively predictable attenuation spectrum. We describe the fabrication process and demonstrate that the performance of the filters is in good agreement with theoretical modelling. We further perform an indicative test of the performance of the filters by making current-voltage measurements of small, underdamped Josephson Junctions at 15 mK and we present the results.

Tancredi, G; Meeson, P J

2014-01-01

213

Vena cava filter  

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.)

214

Metalcasting: Filtering Molten Metal  

International Nuclear Information System (INIS)

A more efficient method has been created to filter cast molten metal for impurities. Read about the resulting energy and money savings that can accrue to many different industries from the use of this exciting new technology

215

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?

2005-10-01

216

The impact of metallic filter media on HEPA filtration  

International Nuclear Information System (INIS)

Traditional HEPA filter systems have limitations that often prevent them from solving many of the filtration problems in the nuclear industry; particularly in applications where long service or storage life, high levels of radioactivity, dangerous decomposition products, chemical aggression, organic solvents, elevated operating temperatures, fire resistance and resistance to moisture are issues. This paper addresses several of these matters of concern by considering the use of metallic filter media to solve HEPA filtration problems ranging from the long term storage of transuranic waste at the WIPP site, spent and damaged fuel assemblies, in glove box ventilation and tank venting to the venting of fumes at elevated temperatures from incinerators, vitrification processes and conversion and sintering furnaces as well as downstream of iodine absorbers in gas cooled reactors in the UK. The paper reviews the basic technology, development, performance characteristics and filtration efficiency, flow versus differential pressure, cleanability and costs of sintered metal fiber in comparison with traditional resin bonded glass fiber filter media and sintered metal powder filter media. Examples of typical filter element and system configurations and applications will be presented The paper will also address the economic case for installing self cleaning pre-filtration, using metallic media, to recover the small volumes of dust that would otherwise blind large volumes of final di otherwise blind large volumes of final disposable HEPA filters, thus presenting a route to reduce ultimate disposal volumes and secondary waste streams. (authors)

217

Hybrid Data Assimilation without Ensemble Filtering  

Science.gov (United States)

The Global Modeling and Assimilation Office is preparing to upgrade its three-dimensional variational system to a hybrid approach in which the ensemble is generated using a square-root ensemble Kalman filter (EnKF) and the variational problem is solved using the Grid-point Statistical Interpolation system. As in most EnKF applications, we found it necessary to employ a combination of multiplicative and additive inflations, to compensate for sampling and modeling errors, respectively and, to maintain the small-member ensemble solution close to the variational solution; we also found it necessary to re-center the members of the ensemble about the variational analysis. During tuning of the filter we have found re-centering and additive inflation to play a considerably larger role than expected, particularly in a dual-resolution context when the variational analysis is ran at larger resolution than the ensemble. This led us to consider a hybrid strategy in which the members of the ensemble are generated by simply converting the variational analysis to the resolution of the ensemble and applying additive inflation, thus bypassing the EnKF. Comparisons of this, so-called, filter-free hybrid procedure with an EnKF-based hybrid procedure and a control non-hybrid, traditional, scheme show both hybrid strategies to provide equally significant improvement over the control; more interestingly, the filter-free procedure was found to give qualitatively similar results to the EnKF-based procedure.

Todling, Ricardo; Akkraoui, Amal El

2014-01-01

218

Venous Thromboembolism After Removal of Retrievable Inferior Vena Cava Filters  

International Nuclear Information System (INIS)

The purpose of this study was to examine the incidence of new or recurrent venous thromboembolism (VTE) after retrieval of inferior vena cava (IVC) filters and risk factors associated with such recurrence. Between March 2001 and September 2008, at our institution, implanted retrievable vena cava filters were retrieved in 76 patients. The incidence of new or recurrent VTE after retrieval was reviewed and numerous variables were analyzed to assess risk factors for redevelopment of VTE after filter retrieval. In 5 (6.6%) of the 76 patients, redevelopment or worsening of VTE was seen after retrieval of the filter. Three patients (4.0%) had recurrent deep venous thrombosis (DVT) in the lower extremities and 2 (2.6%) had development of pulmonary embolism, resulting in death. Although there was no significant difference in the incidence of new or recurrent VTE related to any risk factor investigated, a tendency for development of VTE after filter retrieval was higher in patients in whom DVT in the lower extremities had been so severe during filter implantation that interventional radiological therapies in addition to traditional anticoagulation therapies were required (40% in patients with recurrent VTE vs. 23% in those without VTE; p = 0.5866 according to Fisher's exact probability test) and in patients in whom DVT remained at the time of filter retrieval (60% in patients with recurrent VTE vs. 37% in those without VTE; p = 0.3637). In conclusion, new or recurrent VTE was r In conclusion, new or recurrent VTE was rare after retrieval of IVC filters but was most likely to occur in patients who had severe DVT during filter implantation and/or in patients with a DVT that remained at the time of filter retrieval. We must point out that the fatality rate from PE after filter removal was high (2.6%).

219

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

2006-06-01

220

Dust collection with bag filters and envelope filters  

International Nuclear Information System (INIS)

The state of the art in the field of bag filters is reviewed in great detail, with special regard to the practical aspects of planning, constructing, selecting and operating filter systems. The book contains three main chapters. Chapter 1 reviews the theoretical and experimental basic research on separation and pressure loss phenomena. Chapter 2 discusses the central part of the filter, i.e. the filter medium, and presents a detailed introduction to the problems of filter media development and production. Chapter 3 discusses filter systems: After a classification of filter systems, constructional details and problems of application are discussed. With 203 figs

221

Multilevel Mixture Kalman Filter  

OpenAIRE

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 ...

Xiaodong Wang; Dong Guo; Rong Chen

2004-01-01

222

Bloofi: Multidimensional Bloom Filters  

OpenAIRE

Bloom filters are probabilistic data structures commonly used for approximate membership problems in many areas of Computer Science (networking, distributed systems, databases, etc.). With the increase in data size and distribution of data, problems arise where a large number of Bloom filters are available, and all them need to be searched for potential matches. As an example, in a federated cloud environment, each cloud provider could encode the information using Bloom filt...

Crainiceanu, Adina; Lemire, Daniel

2015-01-01

223

Concurrent filtering and smoothing  

OpenAIRE

This paper presents a novel algorithm for integrating real-time filtering of navigation data with full map/trajectory smoothing. Unlike conventional mapping strategies, the result of loop closures within the smoother serve to correct the real-time navigation solution in addition to the map. This solution views filtering and smoothing as different operations applied within a single graphical model known as a Bayes tree. By maintaining all information within a single graph, the optimal linear e...

Kaess, Michael; Williams, Stephen; Indelman, Vadim; Roberts, Richard; Leonard, John Joseph; Dellaert, Frank

2012-01-01

224

IMAGE FILTERING IN FPGAS  

OpenAIRE

Convolution kernels are frequently used for image processing and analysis. They can be used to apply different filters on images. These filters can serve either an esthetic purpose (for example, to sharpen or blur an image), or they can be a useful tool for image analysis, a common example of which is edge detection. There are many implementations of convolution of an image with a convolution kernel. They can be software implementations, which runs on a desktop computer, or they can be implem...

Artnik, Martin

2013-01-01

225

Filtering Solid Gabor Noise  

OpenAIRE

Solid noise is a fundamental tool in computer graphics. Surprisingly, no existing noise function supports both high-quality antialiasing and continuity across sharp edges. In this paper we show that a slicing approach is required to preserve continuity across sharp edges, and we present a new noise function that supports anisotropic filtering of sliced solid noise. This is made possible by individually filtering the slices of Gabor kernels, which requires the proper treatment of phase. This i...

Lagae, Ares; Drettakis, George

2011-01-01

226

Dispersion management with filtering.  

Science.gov (United States)

We present analytical and numerical results for dispersion-managed solitons in a fiber link including guiding filters and compensating gain, both taken in the distributed approximation. Stationary propagation regimes with anomalous, zero, and normal path-average dispersion (PAD) are identified. New features, compared with those of the case without filters, are the absence of a critical strength for propagation at zero and normal PAD and, instead, the existence of a critical power for stationary propagation at any PAD. PMID:18071554

Berntson, A; Malomed, B A

1999-04-15

227

Collaboratively Filtering Learning Objects  

OpenAIRE

This chapter describes and discusses the application of collaborative filtering techniques to the design of metadata structures for learning objects, and its implications for instruction. This approach enables context-sensitive discovery and recommendation of learning objects. The discussion is based upon research in developing and evaluating a collaborative filtering system, which enables users to share ratings, opinions, and recommendations about resources on the Web. An additional benefi...

Recker, Mimi M.; Walker, Andrew E.; Wiley, David A.

2001-01-01

228

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.

2013-06-01

229

An improved cone-beam filtered backprojection reconstruction algorithm based on x-ray angular correction and multiresolution analysis  

International Nuclear Information System (INIS)

With the extensive application of industrial computed tomography in the field of non-destructive testing, how to improve the quality of the reconstructed image is receiving more and more concern. It is well known that in the existing cone-beam filtered backprojection reconstruction algorithms the cone angle is controlled within a narrow range. The reason of this limitation is the incompleteness of projection data when the cone angle increases. Thus the size of the tested workpiece is limited. Considering the characteristic of X-ray cone angle, an improved cone-beam filtered back-projection reconstruction algorithm taking account of angular correction is proposed in this paper. The aim of our algorithm is to correct the cone-angle effect resulted from the incompleteness of projection data in the conventional algorithm. The basis of the correction is the angular relationship among X-ray source, tested workpiece and the detector. Thus the cone angle is not strictly limited and this algorithm may be used to detect larger workpiece. Further more, adaptive wavelet filter is used to make multiresolution analysis, which can modify the wavelet decomposition series adaptively according to the demand for resolution of local reconstructed area. Therefore the computation and the time of reconstruction can be reduced, and the quality of the reconstructed image can also be improved. (author)

230

Interactive Kalman filtering  

Science.gov (United States)

Data assimilation via the extended Kaiman filter can become problematic when the assimilating model is strongly nonlinear, primarily in connection with sharp, "switchlike" changes between different regimes of the system. The filter seems too inert to follow those switches quickly enough, a fact that can lead to a complete failure when the switches occur often enough. In this paper we replace the key feature of the filter, the use of local linearity for the error model update, with a principle that uses a more global approach through the utilization of a set of preselected regimes. The method uses all regime error models simultaneously. Being mutually incompatible, a compromise between the different error models is found through the use of a weighting function that reflects the `closeness' of the error model to the correct model. To test the interactive Kaiman filter a series of numerical experiments is performed using the double-well system and the well-known Lorenz system, and the results are compared to the extended Kaiman filter. It turns out that, depending on the set of preselected regimes, the performance is worse than, comparable to, or better than that of the extended Kaiman filter.

Bürger, Gerd; Cane, Mark A.

1994-04-01

231

TRADITIONAL FERMENTED FOODS OF LESOTHO  

Directory of Open Access Journals (Sweden)

Full Text Available 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 with added hops and mafi (spontaneously fermented milk, were found to be the main fermented foods prepared and consumed at household level in Lesotho. Motoho is a thin gruel, popular as refreshing beverage as well as a weaning food. Sesotho is sorghum based alcoholic beverage prepared for household consumption as well as for sale. It is consumed in the actively fermenting state. Mafi is the name given to spontaneously fermented milk with a thick consistency. Little research has been done on the technological aspects, including the microbiological and biochemical characteristics of fermented foods in Lesotho. Some of the traditional aspects of the preparation methods, such as use of earthenware pots, are being replaced, and modern equipment including plastic utensils are being used. There is need for further systematic studies on the microbiological and biochemical characteristics of these these products.

Tendekayi H. Gadaga

2013-06-01

232

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

2013-01-01

233

Accurate and Efficient Filtering using Anisotropic Filter Decomposition  

OpenAIRE

Efficient filtering remains an important challenge in computer graphics, particularly when filters are spatially-varying, have large extent, and/or exhibit complex anisotropic profiles. We present an efficient filtering approach for these difficult cases based on anisotropic filter decomposition (IFD). By decomposing complex filters into linear combinations of simpler, displaced isotropic kernels, and precomputing a compact prefiltered dataset, we are able to interactively apply any number of...

Soler, Cyril; Bagher, Mahdi; Nowrouzezahrai, Derek

2013-01-01

234

Fully optimal filter for ALLEGRO  

Science.gov (United States)

The FAST and SLOW filters are compared when applied to data from one-mode and two-mode resonant gravitational wave detectors. There is no substantial difference between the performance of two filters in the case of the one-mode detector. Notable reduction of the noise temperature is achieved for a two-mode detector when filtering the data with the FAST filter. We explain the principal reason for the better performance of the FAST filter with respect to the SLOW filter. We also observed that the performance of the FAST filter depends on the ratio ? between the thermal narrow band noise and the SQUID amplifier white noise.

Santostasi, Giovanni

2004-03-01

235

Fully optimal filter for ALLEGRO  

Energy Technology Data Exchange (ETDEWEB)

The FAST and SLOW filters are compared when applied to data from one-mode and two-mode resonant gravitational wave detectors. There is no substantial difference between the performance of two filters in the case of the one-mode detector. Notable reduction of the noise temperature is achieved for a two-mode detector when filtering the data with the FAST filter. We explain the principal reason for the better performance of the FAST filter with respect to the SLOW filter. We also observed that the performance of the FAST filter depends on the ratio {gamma} between the thermal narrow band noise and the SQUID amplifier white noise.

Santostasi, Giovanni [Physics and Astronomy Department, Louisiana State University, Baton Rouge, LA 70803-4001 (United States)

2004-03-07

236

Fractional vortex dipole phase filter  

Science.gov (United States)

In spatial filtering experiments, the use of vortex phase filters plays an important role in realizing isotropic edge enhancement. In this paper, we report the use of a vortex dipole phase filter in spatial filtering. A dipole made of fractional vortices is used, and its filtering characteristics are studied. It is observed that the filter performance can be tuned by varying the distance of separation between the vortices of the dipole to achieve better contrast and output noise suppression, and when this distance tends to infinity, the filter performs like a 1-D Hilbert mask. Experimental and simulation results are presented.

Sharma, Manoj Kumar; Joseph, Joby; Senthilkumaran, Paramasivam

2014-10-01

237

Choosing and using astronomical filters  

CERN Document Server

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

Griffiths, Martin

2014-01-01

238

Filters for cathodic arc plasmas  

Science.gov (United States)

Cathodic arc plasmas are contaminated with macroparticles. A variety of magnetic plasma filters has been used with various success in removing the macroparticles from the plasma. An open-architecture, bent solenoid filter, with additional field coils at the filter entrance and exit, improves macroparticle filtering. In particular, a double-bent filter that is twisted out of plane forms a very compact and efficient filter. The coil turns further have a flat cross-section to promote macroparticle reflection out of the filter volume. An output conditioning system formed of an expander coil, a straightener coil, and a homogenizer, may be used with the magnetic filter for expanding the filtered plasma beam to cover a larger area of the target. A cathodic arc plasma deposition system using this filter can be used for the deposition of ultrathin amorphous hard carbon (a-C) films for the magnetic storage industry.

Anders, Andre (Albany, CA); MacGill, Robert A. (Richmond, CA); Bilek, Marcela M. M. (Engadine, AU); Brown, Ian G. (Berkeley, CA)

2002-01-01

239

Spatial filtering efficiency of monostatic biaxial lidar: analysis and applications.  

Science.gov (United States)

Results of lidar modeling based on spatial-angular filtering efficiency criteria are presented. Their analysis shows that the low spatial-angular filtering efficiency of traditional visible and near-infrared systems is an important cause of low signal/background-radiation ratio (SBR) at the photodetector input The low SBR may be responsible for considerable measurement errors and ensuing the low accuracy of the retrieval of atmospheric optical parameters. As shown, the most effective protection against sky background radiation for groundbased biaxial lidars is the modifying of their angular field according to a spatial-angular filtering efficiency criterion. Some effective approaches to achieve a high filtering efficiency for the receiving system optimization are discussed. PMID:12510915

Agishev, Ravil R; Comeron, Adolfo

2002-12-20

240

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,

2011-04-01

241

Boolean filters of distributive lattices  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper we introduce the notion of Boolean filters in a pseudo-complemented distributive lattice and characterize the class of all Boolean filters. Further a set of equivalent conditions are derived for a proper filter to become a prime Boolean filter. Also a set of equivalent conditions is derived for a pseudo-complemented distributive lattice to become a Boolean algebra. Finally, a Boolean filter is characterized in terms of congruences.

M. Sambasiva Rao

2013-07-01

242

NOTCH FILTER USING SIMULATED INDUCTOR  

Directory of Open Access Journals (Sweden)

Full Text Available The design of analog filters at low frequencies is not possible because the size of inductors becomes very large. In such cases, the simulated inductors using operational amplifiers are used. This paper deals with the implementation of notch filter using band pass filter which uses simulated inductor where the direct implementation of notch filter using simulated inductor is not possible because of floating inductor. The design of notch filter and the simulation done in PSPICE is presented.

D.SUSAN,

2011-06-01

243

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

2010-01-01

244

Trust and Traditions in Transitions  

DEFF Research Database (Denmark)

On New Year’s Eve 2013, months of talks on ‘Dealing with the past’, ‘Flags’ and ‘Parades’ ended without agreement on how to move towards a reconciliation of positions in Northern Ireland. The failure of the talks illustrates the importance of culture and (mis)trust in divided societies, where politics often pivot around whose culture shall be official and whose subordinated, whose history shall be remembered and whose forgotten (Jordan and Weedon 1995). These struggles are particularly intense in times of transition where traditions, power relations and frames of relevant remembrance are reconfigured. Historically, parading traditions have been important cultural carriers of identity in Northern Ireland. (Jarman 1997). Correspondingly, the marching season has been an arena for politico-cultural struggles and resistance, indexing relations of trust between communities, between society and the state and more recently, trust in the peace process. As the contest over meaning is always determined by the context of articulation, this paper examines the role of parades in the current ‘post-conflict’ phase of the peace process. Using theories of cultural and collective memory (Assman 2011, Olick 2011, Bodnar 1994), politics of affect (Hogget and Thompson) and data from republican and loyalist parades in North Belfast it is argued that a) there is fear of memory collapse in particular communities on the margins of the peace process with a conscious doubling of efforts to articulate the hidden recesses of memory in the current transition. And b) that patterns of ‘competitive commemoration’ in parades should be understood in relation to the increasing dissonance between vernacular languages of conflict and the official post-conflict discourses in Northern Ireland.

McQuaid, Sara Dybris

245

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

2006-01-01

246

'OBWARZANEK KRAKOWSKI' AS A TRADITIONAL FOOD  

Directory of Open Access Journals (Sweden)

Full Text Available Normal 0 21 The aim of this work was to evaluate the quality and to compare the traditional (‘obwarzanek krakowski’ with the non-traditional (‘obwarzanek’ bakery products. Four samples were analysed for chemical composition and texture and colour of crumb. The analysed products differed in the features of general appearance and chemical composition. The traditional products became much more hard during storage time than the non-traditional ones.doi:10.5219/197

Joanna Sobolewska-Zieli?ska

2012-12-01

247

Design of Wideband Microstrip Filters with Non-Equiripple Responses and Low Sensitivity  

CERN Document Server

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

2013-01-01

248

Systolic Filter Design Using Multi-Filtering Techniques  

Directory of Open Access Journals (Sweden)

Full Text Available To improve the performance of system in terms of processing power, a new architecture and clocking technique is to be realized in this paper. To process the signal in Embedded Parallel Systolic Filters (EPSF and to eliminate the noise present in the signal using flag-bit and flicker clock condition. Kalman filter and extended kalman filter are the filtering techniques used by systolic arrays that can simultaneously triggered on all data elements with different clock cycles. Kalman filter and extended kalman filter to work in two conditions namely with and without flag-bit, flicker clock are to be synthesized and compared.

DEEPAN RAJ.B

2013-04-01

249

Infusing Qualitative Traditions in Counseling Research Designs  

Science.gov (United States)

Research traditions serve as a blueprint or guide for a variety of design decisions throughout qualitative inquiry. This article presents 6 qualitative research traditions: grounded theory, phenomenology, consensual qualitative research, ethnography, narratology, and participatory action research. For each tradition, the authors describe its…

Hays, Danica G.; Wood, Chris

2011-01-01

250

Microwave superconducting filters  

Science.gov (United States)

Four-pole, parallel-coupled microstrip line filters were fabricated using epitaxial YBa2Cu3O7 (YBCO) films deposited by off-axis sputtering on LaAlO3 substrates. Filters were made with and without superconducting ground planes. Because it is not yet possible to grow in-situ epitaxial films on both sides of a substrate, two separate substrates were used, one for the filter and one for the ground-plane. The devices were packaged so that the microstrip-to-ground-plane distance was the thickness of one of the substrates (0.43 mm). Passband characteristics, input power, and temperature dependence were measured, as well as the thermal cycling stability.

Talisa, S. H.; Janocko, M. A.; Jones, C. K.; McAvoy, B. R.; Talvacchio, J.

1991-03-01

251

Stack filter classifiers  

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

2009-01-01

252

Morphing Ensemble Kalman Filters  

CERN Document Server

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

2007-01-01

253

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

2013-01-01

254

Design and Implementation for a Non Linear State Filter for LEO Micro Satellite  

Directory of Open Access Journals (Sweden)

Full Text Available This study preliminarily investigates the numerical application of both Extended Kalman Filter (EKF (which has traditionally been used for non linear estimation and a relatively new filter, Unscented Kalman Filter (UKF to the nonlinear estimation problem. The new method can be applied to nonlinear systems without the linearization process necessary for the EKF and it does not demand a Gaussian distribution of noise and what's more, its ease of implementation and more accurate estimation features enables it to demonstrate its good performance. Present experimental results and analysis indicate that unscented Kalman filtering UKF have shown better performances in presence of the severe nonlinearity in state equations.

S. Chouraqui

2009-01-01

255

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

256

Manufacturing a low-cost ceramic water filter and filter system for the elimination of common pathogenic bacteria  

Science.gov (United States)

Africa is one of the most water-scarce continents in the world but it is the lack of potable water which results in diarrhoea being the leading cause of death amongst children under the age of five in Africa (696 million children under 5 years old in Africa contract diarrhoea resulting in 2000 deaths per day: WHO and UNICEF, 2009). Most potable water treatment methods use bulk water treatment not suitable or available to the majority of rural poor in Sub-Saharan Africa. One simple but effective way of making sure that water is of good quality is by purifying it by means of a household ceramic water filter. The making and supply of water filters suitable for the removal of suspended solids, pathogenic bacteria and other toxins from drinking water is therefore critical. A micro-porous ceramic water filter with micron-sized pores was developed using the traditional slip casting process. This locally produced filter has the advantage of making use of less raw materials, cost, labour, energy and expertise and being more effective and efficient than other low cost produced filters. The filter is fitted with a silicone tube inserted into a collapsible bag that acts as container and protection for the filter. Enhanced flow is obtained through this filter system. The product was tested using water inoculated with high concentrations of different bacterial cultures as well as with locally polluted stream water. The filter is highly effective (log10 > 4 with 99.99% reduction efficiency) in providing protection from bacteria and suspended solids found in natural water. With correct cleaning and basic maintenance this filter technology can effectively provide drinking water to rural families affected by polluted surface water sources. This is an African solution for the more than 340 million people in Africa without access to clean drinking water (WHO and UNICEF, 2008).

Simonis, J. J.; Basson, A. K.

257

Firewall: Packet Filters  

Science.gov (United States)

This brief interactive activity, by Electromechanical Digital Library and Wisconsin Technical College System faculty members Joseph Wetzel and Douglas Tabbutt, provides an interactive lesson on packet filters to demonstrate their use. After a brief explanation, there is a very useful activity that allows the user to control theoretical settings to try to block a certain port from transferring information â?? itâ??s a good test to verify if the concept is understood. This should prove a useful resource for students or teachers looking to introduce the concept of packet filters.

Tabbutt, Douglas

258

Efficient Iterated Filtering  

DEFF Research Database (Denmark)

Parameter estimation in general state space models is not trivial as the likelihood is unknown. We propose a recursive estimator for general state space models, and show that the estimates converge to the true parameters with probability one. The estimates are also asymptotically Cramer-Rao efficient. The proposed estimator is easy to implement as it only relies on non-linear filtering. This makes the framework flexible as it is easy to tune the implementation to achieve computational efficiency. This is done by using the approximation of the score function derived from the theory on Iterative Filtering as a building block within the recursive maximum likelihood estimator.

Lindstro?m, Erik; Ionides, Edward

2012-01-01

259

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

2010-12-01

260

Kazakh Traditional Dance Gesture Recognition  

Science.gov (United States)

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

2014-04-01

261

Real-time color imaging using the vectorial order statistics filters  

Science.gov (United States)

Color image and video sequence restoration and improvement are complicated due to presence of various kinds of random noise. Impulsive noise is introduced by acquisition or broadcasting errors into communication channels. Non linear filters can provide good performance in terms of the signal-to-noise ratio in different levels of corruption as soon as minimum error chromaticity and minimum perceptual error. This paper presents the capability and real-time processing features of several processing techniques such as "directional processing", "non parametric approaches" and "order statistics" filters. Some of such the filters were: Median Filter (MF), Vector Median Filter (VMF), -Trimmed Mean Filter (ATMF), Generalized Vector Directional Filter (GVDF), Adaptive Multichannel Non Parametric Filter (AMNF), Median M-type K-Nearest Neighbour (MM-KNN) filter, Wilcoxon M-type K-Nearest Neighbour (WM-KNN) filter, Ansari-Bradley-Siegel-Tukey M-Type K-Nearest Neighbor (ABSTM-KNN) filter, etc. Extensive simulations in reference color RGB images "Lena", "Mandrill", "Peppers" and QCIF format video sequences (Miss America, Flowers and Foreman) have demonstrated that the proposed filters consistently can outperform the known nonlinear filters. The used performance criteria in color imaging were the traditional ones: PSNR, MAE and other specific for color imaging, NCD and MCRE. The real-time implementation of image filtering was realized on the DSP TMS320C6701. The processing time of proposed filters includes the duration of data acquisition, processing and store data. We simulated impulse corrupted color image QCIF sequences to demonstrate that some of the proposed and analyzing filters potentially could provide on line processing to quality video transmission of the images.

Ponomaryov, Volodymyr I.; Rosales, Alberto J.; Gallegos Funes, Francisco

2004-05-01

262

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

2013-10-01

263

Real Time Digital Filters: Finite Impulse?Response Filters  

OpenAIRE

In the past, chemists were not concerned with filtering, because data were obtained using analog instrumentation with hardware analog filters. The most common implementation of a filter consisted of a network of resistors and capacitors to affect the frequencey characteristics of signal transfer. However, with the recent advent of affordable digital processor-based data acquisition systems, real-time digital filtering is becoming an ever-increasing facet of the modern analytical laboratory. P...

Bialkowski, Stephen E.

1988-01-01

264

Running FIR and IIR filtering using filter banks  

OpenAIRE

The computational complexity of running FIR (finite-impulse response) and IIR (infinite-impulse response) filtering using multirate filter banks is considered. No restrictions are put on signal, filter, or block lengths. It is shown how to map long running convolutions into smaller ones by using filter banks based on aperiodic convolution algorithms and short-time Fourier transforms. With the proposed approach, good tradeoffs among computational complexity, system architecture, and input-outp...

Vetterli, Martin

1988-01-01

265

The Rao-Blackwellized Particle Filter: A Filter Bank Implementation  

OpenAIRE

For computational efficiency, it is important to utilize model structure in particle filtering. One of the most important cases occurs when there exists a linear Gaussian substructure, which can be efficiently handled by Kalman filters. This is the standard formulation of the Rao-Blackwellized particle filter (RBPF). This contribution suggests an alternative formulation of this well-known result that facilitates reuse of standard filtering components and which is also suitabl...

Hendeby, Gustaf; Karlsson, Rickard; Gustafsson, Fredrik

2010-01-01

266

EnFilter: a Password Enforcement and Filter  

OpenAIRE

EnFilter is a Proactive Password Checking System, designed to avoid password guessing attacks. It is made of a set of configurable filters, each one based on a specific pattern recognition measure that can be tuned by the system administrator depending on the adopted password policy. Filters use decision trees, lexical analysers, as well as Levenshtein distance based techniques. EnFilter is implemented for Windows 2000/2003/XP.

Bergadano, Francesco; Ruffo, Giancarlo

2005-01-01

267

The Kalman filter  

OpenAIRE

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

2002-01-01

268

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))

1992-01-01

269

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)

1992-12-01

270

Digital hum filtering  

Science.gov (United States)

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.

1994-01-01

271

Fission product filter  

International Nuclear Information System (INIS)

The fission product filter for He consists of a winding body composed of two corrugated metal sheets simultaneously wound on a core laterally reversed. It is inserted into an enclosing tube and held at top and bottom by a star-shaped yoke. (orig./PW)

272

Metamaterial Tunable Filter Design  

OpenAIRE

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.

2013-01-01

273

OPTIMIZATION OF ADVANCED FILTER SYSTEMS  

Energy Technology Data Exchange (ETDEWEB)

Two advanced, hot gas, barrier filter system concepts have been proposed by the Siemens Westinghouse Power Corporation to improve the reliability and availability of barrier filter systems in applications such as PFBC and IGCC power generation. The two hot gas, barrier filter system concepts, the inverted candle filter system and the sheet filter system, were the focus of bench-scale testing, data evaluations, and commercial cost evaluations to assess their feasibility as viable barrier filter systems. The program results show that the inverted candle filter system has high potential to be a highly reliable, commercially successful, hot gas, barrier filter system. Some types of thin-walled, standard candle filter elements can be used directly as inverted candle filter elements, and the development of a new type of filter element is not a requirement of this technology. Six types of inverted candle filter elements were procured and assessed in the program in cold flow and high-temperature test campaigns. The thin-walled McDermott 610 CFCC inverted candle filter elements, and the thin-walled Pall iron aluminide inverted candle filter elements are the best candidates for demonstration of the technology. Although the capital cost of the inverted candle filter system is estimated to range from about 0 to 15% greater than the capital cost of the standard candle filter system, the operating cost and life-cycle cost of the inverted candle filter system is expected to be superior to that of the standard candle filter system. Improved hot gas, barrier filter system availability will result in improved overall power plant economics. The inverted candle filter system is recommended for continued development through larger-scale testing in a coal-fueled test facility, and inverted candle containment equipment has been fabricated and shipped to a gasifier development site for potential future testing. Two types of sheet filter elements were procured and assessed in the program through cold flow and high-temperature testing. The Blasch, mullite-bonded alumina sheet filter element is the only candidate currently approaching qualification for demonstration, although this oxide-based, monolithic sheet filter element may be restricted to operating temperatures of 538 C (1000 F) or less. Many other types of ceramic and intermetallic sheet filter elements could be fabricated. The estimated capital cost of the sheet filter system is comparable to the capital cost of the standard candle filter system, although this cost estimate is very uncertain because the commercial price of sheet filter element manufacturing has not been established. The development of the sheet filter system could result in a higher reliability and availability than the standard candle filter system, but not as high as that of the inverted candle filter system. The sheet filter system has not reached the same level of development as the inverted candle filter system, and it will require more design development, filter element fabrication development, small-scale testing and evaluation before larger-scale testing could be recommended.

R.A. Newby; M.A. Alvin; G.J. Bruck; T.E. Lippert; E.E. Smeltzer; M.E. Stampahar

2002-06-30

274

Optically bistable interference filter  

Science.gov (United States)

In general the temperature dependence of refractive index of coating materials is usually small. The most notable exception being the lead telluride. Thinfilm filters made of PbTe possess anomalously high nortlinearily in refractive index. We have investigated the phenomenon theoretically and experimexitally. 2 . BISTABLE CHARACTERISTICS OF INTERFERENCE FILTERS It can be proved that the transmittance and reflectance of a twin-cavity NLIF which consists of two F-B filters coupled by a single low-index are given by 2 a(1r1 )(1-r0) T --i. -. (1) -d (1r01) (1r12) (1-i-Fsin 4)(1+sin p) where a r01 F . Te phase change of the cavity 0 IS 2r0dnAI0D (2) 2k5dT 1k where the absorbtance A 00 the initial detunning of fresonance and the first term on the right side of the equation(1)-(2) the output characteristics of the NLIF can be calculated. 3 . EXPERIMENTAL CASE The interference filters suggested to be used in my research will be made by vacuum deposition with a thermal source. The filters will be made according to the prescripti The dominant mechanism responsible for d(nhl) must be the change in the refractive index. A low limit on the OB switch-on time is found to be O. 35us and switch-off time is 5. 5us. 4. REFERENCES 1. W. T. Feng " Temperature effects on properties of zinc selenide and lead telluride" to be published in Infrared Physics. 2. H. S. Carslaw Conduction

Feng, Weiting

1990-07-01

275

Filters used in scoliosis radiography  

International Nuclear Information System (INIS)

The use of X-ray filters during full spinal radiography for scoliosis in adolescent patients is discussed. The filters compensate for differences in body thickness while maintaining optimum image quality. They also help to reduce patient dose

276

HEVC deblocking filtering and decisions  

Science.gov (United States)

The emerging High Efficiency Video Coding (HEVC) standard uses a block-based coding scheme, which may cause blocking artifacts, especially at lower bitrates. An adaptive in-loop deblocking filter is used in the standard to reduce visible artifacts at block boundaries. The deblocking filter detects artifacts at the block boundaries and attenuates them by applying a selected filter. This paper will present deblocking decisions and filtering operations that are used in HEVC.

Norkin, Andrey; Andersson, Kenneth; Fuldseth, Arild; Bjøntegaard, Gisle

2012-10-01

277

Folktale Narration: A Retreating Tradition  

Directory of Open Access Journals (Sweden)

Full Text Available To talk of folktales in the Bhutanese context is to discuss ona literary genre popularly known as khaju1 or ‘oraltransmission’. It serves as an important tool ofcommunication between one generation and another. Amongothers, the folktales comprise an indispensable portion of oralliterature. In it is seen the manifestation of the popularimagination and creativity representing the Bhutanesepatrimony which has been passed down from mouth to earsince time immemorial. The role that it plays in thetransmission of moral values, philosophy, beliefs, humour,etiquette, and many other traits specific to the Bhutanesesociety holds an inescapably eminent place. Despite thisimportance, the documentation of folktales in Bhutan is stillin its infancy. Till the mid-twentieth century, education wasimparted through the monasteries and all the people did nothave access to it. Furthermore, the scarcity of writing andprinting facilities compounded the difficulty and consequentlythe larger section of the population remained illiterate. Evenafter schools were opened and facilities provided free of cost,the documentation of folktales took quite sometime to jumpfrom the springboard. It was only in 1984 that Dasho SherabThaye published his first volume of the collection of folktalesfollowed suite by another two in 1986. This was the debutand now we have authors like Kunzang Choden, Kinley Wangmo, Françoise Pommaret and a few others who hadfollowed the footsteps of Dasho Sherab Thaye. However, thecollections made until today is just a drop considering thevast reservoir of folktales that lies recorded in the memoriesof the Bhutanese. It requires the efforts of many Bhutaneseeven to document a part of this inexhaustible patrimony.This, however, is not to indicate that the Bhutanese folktalesare different form the rest. In fact, ‘…folktales are the same allover, for they tell of people. Not ordinary people like those wemeet on our journey through life, but the whole secret andexciting society of one eyed sorcerers, evil giants, handsomeprinces and dancing fairies….’ 2 All the same, what is specialabout the Bhutanese folktales is that, it still is a livingtradition in many pockets of rural Bhutan. In the villageswhich are far flung from motor roads, the narration offolktales in the pastures, and in the evenings are even todayvery much alive. However, the question is, how long will itcontinue to survive? Will the development process engulf thisbeautiful tradition? And, what could be done to keep thisheritage alive?

Tandin Dorji

2002-01-01

278

Samarium polarising filters at ISIS  

International Nuclear Information System (INIS)

The status of the programme to develop samarium resonance absorption neutron polarising filters at ISIS is summarised. The results of the most recent measurements of filter performance are described. Some suggestions are made for future development work and the results of calculations of the performance of a proposed chopper spectrometer, incorporating polarising filters are given. (author)

279

Assessment of ceramic membrane filters  

Energy Technology Data Exchange (ETDEWEB)

The objectives of this project include the development of analytical models for evaluating the fluid mechanics of membrane coated, dead-end ceramic filters, and to determine the effects of thermal and thermo-chemical aging on the material properties of emerging ceramic hot gas filters. A honeycomb cordierite monolith with a thin ceramic coating and a rigid candle filter were evaluated.

Ahluwalia, R.K.; Geyer, H.K.; Im, K.H. [and others

1995-08-01

280

Spatial Filter with Volume Gratings for High-peak-power Multistage Laser Amplifiers  

CERN Document Server

The regular spatial filters comprised of lens and pinhole are essential component in high power laser systems, such as lasers for inertial confinement fusion, nonlinear optical technology and directed-energy weapon. On the other hand the pinhole is treated as a bottleneck of high power laser due to harmful plasma created by the focusing beam. In this paper we present a spatial filter based on angular selectivity of Bragg diffraction grating to avoid the harmful focusing effect in the traditional pinhole filter. A spatial filter consisted of volume phase gratings in two-pass amplifier cavity were reported. Two-dimensional filter was proposed by using single Pi-phase-shifted Bragg grating, numerical simulation results shown that its angular spectrum bandwidth can be less than 160urad. The angular selectivity of photo-thermo-refractive glass and RUGATE film filters, construction stability, thermal stability and the effects of misalignments of gratings on the diffraction efficiencies under high-pulse-energy laser...

Tan, Yi-zhou; Zheng, Guang-wei; Shen, Ben-jian; Pan, Heng-yue; Li, Liu

2012-01-01

281

Inorganic UV filters  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese A preocupação com o câncer de pele hoje em dia vem crescendo cada vez mais principalmente em países tropicais, onde a incidência da radiação 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 relação aos orgânicos, tais como fotoestabilidade, ausência de irritabilidade e amplo espectro de proteção. Entretanto, em razão de apresentarem alto índice de refração, os ativos inorgânicos conferem aos protetores solares aparência esbranquiçada, diminuindo sua atratividade estética. Muitas alternativas têm 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 obtenção de protetores solares inorgânicos (rotas de sínteses propostas nos últimos anos) quanto na permeabilidade, na segurança e em outros aspectos relacionados à nova geração 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.

Eloísa Berbel, Manaia; Renata Cristina Kiatkoski, Kaminski; Marcos Antonio, Corrêa; Leila Aparecida, Chiavacci.

2013-06-01

282

Self-Tuning Synthesis Filter against Mutual Coupling and Interferences for GNSS and Its Implementation on Embedded Board  

OpenAIRE

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...

Chung-Liang Chang

2010-01-01

283

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)

284

The Ecological Ideology in Traditional Chinese Culture  

OpenAIRE


Traditional Chinese Culture includes many ecological ideas. This paper studies about some characteristics of them in three aspects. First, the feature that man is an integral part of nature in Traditional Chinese Culture provides potential foundation for harmonic coexistence of man and nature. Second, the concept of “the axes and bills enter the hills and forests only at the proper time” in Traditional Chinese Culture provides a rational basis for harmonic coex...

Liu, Jing-wei

2006-01-01

285

On-Line learning and Traditional Organizations  

OpenAIRE

English: This paper proposes that a shift of focus is required when traditional educational institutions are embarking on the task of implementing on-line learning programs. Traditional organizations of higher educational institutions are bureaucracies, structured to serve and support educational programs with lecture-based learning processes. The allocation of resources is closely related to the traditional tasks of planning and preparing the use of lecture theatres, arranging exams in tradi...

Faugli, Bjørn

2003-01-01

286

Bilateral edge filter: photometrically weighted, discontinuity based edge detection.  

Science.gov (United States)

Edge-detection algorithms have the potential to play an increasingly important role both in single particle analysis (for the detection of randomly oriented particles), and in tomography (for the segmentation of 3D volumes). However, the majority of traditional linear filters are significantly affected by noise as well as artefacts, and offer limited selectivity. The Bilateral edge filter presented here is an adaptation of the Bilateral filter [Jiang, W., Baker, M.L., Wu, Q., Bajaj, C., Chiu, W., 2003. Applications of a bilateral denoising filter in biological electron microscopy. J. Struct. Biol. 144, 114-122] designed for enhanced edge detection. It uses photometric weighting to identify significant discontinuities (representing edges), minimizing artefacts and noise. Compared with common edge-detectors (LoG, Marr-Hildreth) the Bilateral edge filter yielded significantly better results. Indeed data was of a similar quality to that of the Canny edge-detector, which is considered as a leading standard in edge detection [Basu, M., 2002. Gaussian-based edge-detection methods-a survey. IEEE Trans. Syst. Man Cybern. C Appl. Rev. 32, 252-260]. Compared to the Canny edge-detector the Bilateral edge-detector has the advantages that it only requires the adjustment of a single parameter, is theoretically faster for reasonably sized images, and can be used in selective contrast enhancement of images. The simplicity and speed of the filter for single particle and tomographic analysis are discussed. PMID:17822922

Pantelic, Radosav S; Ericksson, Geoffery; Hamilton, Nicholas; Hankamer, Ben

2007-10-01

287

Simon nitinol filter  

International Nuclear Information System (INIS)

The incidence of inferior vena cava (IVC) thrombosis associated with the Simon Nitinol filter was reviewed at two institutions in 20 patients with lower- extremity deep venous thrombosis within 12 months. Ten patients had underlying malignancy. Clinical findings were correlated with findings of color-flow US, spin-echo (SE) MR imaging, and gradient-echo (GE) MR imaging of the IVC. Four of the 20 patients developed symptoms of IVC thrombosis (bilateral leg edema) within 5 weeks. MR imaging in all four documented IVC thrombosis (absence of intracaval flow void on SE images, absence of increased signal on GE images), and each had underlying malignancy (three pelvic tumors, one renal cell carcinoma). The authors conclude that patients with tumors, especially genitourinary primary tumors, may be at increased risk of IVC thrombosis in the presence of this filter, possibly because of pelvic venous compression or reduced renal vein inflow with prior nephrectomy; MR imaging is very useful for following IVC patency

288

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

2013-06-01

289

Wetland Filter Model  

Science.gov (United States)

In this quick activity (located on page 2 of the PDF), learners will model how wetlands act as natural filters for the environment. Learners prepare a mixture of water, soil, gravel, and leaves and then pour it down a piece of artificial grass, observing how much gets trapped in the fake grass and comparing water at the bottom with the initial âpollutedâ sample. Relates to the linked video, DragonflyTV GPS: Wetlands.

Twin Cities Public Television, Inc.

2007-01-01

290

Subjective Collaborative Filtering  

OpenAIRE

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 Jac...

Caruso, Fabrizio; Giuffrida, Giovanni; Zarba, Calogero

2011-01-01

291

Multimodal microwave filters  

OpenAIRE

This thesis presents the conception, design and implementation of new topologies of multimodal microwave resonators and filters, using a combination of uniplanar technologies such as coplanar waveguide (CPW), coplanar strips (CPS) and slotlines. The term "multimodal" refers to uniplanar circuits in which the two fundamental modes of the CPW propagate (the even and the odd mode). By using both modes of the CPW, it is possible to achieve added functions, such as additional transmission zeros to...

Contreras Lizarraga, Adria?n Arturo

2013-01-01

292

Superconducting notch filter  

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/ Nb3Sn or Nb3Ge thin films. In the present design, circuit Q's of about 2 x 103 were obtained with 50-ohm source and output impedance

293

Mangroves: Living Filters  

Science.gov (United States)

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.

2008-03-26

294

Filter Bank Fusion Frames  

OpenAIRE

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 con...

Chebira, Amina; Fickus, Matthew; Mixon, Dustin G.

2010-01-01

295

Optimization of HEPA filter design  

International Nuclear Information System (INIS)

Often high efficiency filters are associated with high pressure drop, particularly at high airflow velocity. With design optimization, a cost effective design of clean room can be achieved by lowering energy cost or reducing the size of the filter housing. Through mathematical analysis, optimum filter designs are obtained for the separator type HEPA filter. In the mathematical analysis, a similarity solution obtained from Navier-Stoke's equation for airflow between the filter pleat spacing with uniform mass addition and extraction is applied to each finite element along the pleat channel. The optimum pleat aspect ratio is obtained by combining the expressions for the axial pressure gradient for upstream channel with mass extraction, the axial pressure gradient for downstream channel with mass addition, and the filter media flow characteristics for finite elements along the filter pleat channel with varying wall airflow rate

296

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)

297

A collaborative filtering similarity measure based on singularities.  

OpenAIRE

Recommender systems play an important role in reducing the negative impact of informa- tion overload on those websites where users have the possibility of voting for their prefer- ences on items. The most normal technique for dealing with the recommendation mechanism is to use collaborative filtering, in which it is essential to discover the most similar users to whom you desire to make recommendations. The hypothesis of this paper is that the results obtained by applying traditional similari...

Bobadilla Sancho, Jesus; Ortega Requena, Fernando; Hernando Esteban, Antonio

2012-01-01

298

Optical filters by the pyrolysis of metal-organics  

OpenAIRE

Optical coatings and filters have enormous applications in every branch of modern optics. Traditionally optical films are deposited by evaporation, sputtering, and by chemical methods. Using these above mentioned techniques it is very difficult to obtain excellent quality films ; that is, films with extremely low values of scattering, absorption and film stress and high corrosion resistance to humidity. Recently developed Ion-Assisted Deposition techniques produce high performance films but s...

Desu, S.

1993-01-01

299

Image Enhancement Algorithm based on Improved Fuzzy Filter  

OpenAIRE

Due to dynamic range compression and contrast enhancement realized simultaneously in traditional image enhancement algorithm based on frequency domain, which cause the low contrast degree, an improved image enhancement algorithm based on fuzzy filter is proposed in this paper. According to subjective feeling of the human visual system to light luminance, the image is processed with the global brightness transform. And the image with the global low contrast degree and the poor effect of edge p...

Shaosheng Sun

2014-01-01

300

Estimation of aircraft aerodynamic derivatives using Extended Kalman Filter  

OpenAIRE

Design of flight control laws, verification of performance predictions, and the implementation of flight simulations are tasks that require a mathematical model of the aircraft dynamics. The dynamical models are characterized by coefficients (aerodynamic derivatives) whose values must be determined from flight tests. This work outlines the use of the Extended Kalman Filter (EKF) in obtaining the aerodynamic derivatives of an aircraft. The EKF shows several advantages over the more traditional...

Curvo M.

2000-01-01

301

OPTIMIZATION OF ADVANCED FILTER SYSTEMS  

Energy Technology Data Exchange (ETDEWEB)

Reliable, maintainable and cost effective hot gas particulate filter technology is critical to the successful commercialization of advanced, coal-fired power generation technologies, such as IGCC and PFBC. In pilot plant testing, the operating reliability of hot gas particulate filters have been periodically compromised by process issues, such as process upsets and difficult ash cake behavior (ash bridging and sintering), and by design issues, such as cantilevered filter elements damaged by ash bridging, or excessively close packing of filtering surfaces resulting in unacceptable pressure drop or filtering surface plugging. This test experience has focused the issues and has helped to define advanced hot gas filter design concepts that offer higher reliability. Westinghouse has identified two advanced ceramic barrier filter concepts that are configured to minimize the possibility of ash bridge formation and to be robust against ash bridges should they occur. The ''inverted candle filter system'' uses arrays of thin-walled, ceramic candle-type filter elements with inside-surface filtering, and contains the filter elements in metal enclosures for complete separation from ash bridges. The ''sheet filter system'' uses ceramic, flat plate filter elements supported from vertical pipe-header arrays that provide geometry that avoids the buildup of ash bridges and allows free fall of the back-pulse released filter cake. The Optimization of Advanced Filter Systems program is being conducted to evaluate these two advanced designs and to ultimately demonstrate one of the concepts in pilot scale. In the Base Contract program, the subject of this report, Westinghouse has developed conceptual designs of the two advanced ceramic barrier filter systems to assess their performance, availability and cost potential, and to identify technical issues that may hinder the commercialization of the technologies. A plan for the Option I, bench-scale test program has also been developed based on the issues identified. The two advanced barrier filter systems have been found to have the potential to be significantly more reliable and less expensive to operate than standard ceramic candle filter system designs. Their key development requirements are the assessment of the design and manufacturing feasibility of the ceramic filter elements, and the small-scale demonstration of their conceptual reliability and availability merits.

R.A. Newby; G.J. Bruck; M.A. Alvin; T.E. Lippert

1998-04-30

302

Market Risk Beta Estimation using Adaptive Kalman Filter  

Directory of Open Access Journals (Sweden)

Full Text Available Market risk of an asset or portfolio is recognized through beta in Capital Asset Pricing Model (CAPM. Traditional estimation techniques emerge poor results when beta in CAPM assumed to be dynamic and follows auto regressive model. Kalman Filter (KF can optimally estimate dynamic beta where measurement noise covariance and state noise covariance are assumed to be known in a state-space framework. This paper applied Adaptive Kalman Filter (AKF for beta estimation when the above covariances are not known and estimated dynamically. The technique is first characterized through simulation study and then applied to empirical data from Indian security market. A odification of the used AKF is also proposed to take care of the problems of AKF implementation onbeta estimation and simulations show that modified method improves the performance of the filter measured by RMSE.

Atanu Das,

2010-06-01

303

DCT based interpolation filter for motion compensation in HEVC  

Science.gov (United States)

High Efficiency Video Coding (HEVC) draft standard has a challenging goal to improve coding efficiency twice compare to H.264/AVC. Many aspects of the traditional hybrid coding framework were improved during new standard development. Motion compensated prediction, in particular the interpolation filter, is one area that was improved significantly over H.264/AVC. This paper presents the details of the interpolation filter design of the draft HEVC standard. The coding efficiency improvements over H.264/AVC interpolation filter is studied and experimental results are presented, which show a 4.0% average bitrate reduction for Luma component and 11.3% average bitrate reduction for Chroma component. The coding efficiency gains are significant for some video sequences and can reach up 21.7%.

Alshin, Alexander; Alshina, Elena; Park, Jeong Hoon; Han, Woo-Jin

2012-10-01

304

Comet and Meteorite Traditions of Aboriginal Australians  

CERN Document Server

Of the hundreds of distinct Aboriginal cultures of Australia, many have oral traditions rich in descriptions and explanations of comets, meteors, meteorites, airbursts, impact events, and impact craters. These views generally attribute these phenomena to spirits, death, and bad omens. There are also many traditions that describe the formation of meteorite craters as well as impact events that are not known to Western science.

Hamacher, Duane W

2014-01-01

305

Vygotsky, Consciousness, and the German Psycholinguistic Tradition  

Science.gov (United States)

This article argues that Vygotsky's choice of word meaning as the basic unit of analysis for cultural psychology connects him to a German psycholinguistic tradition--exemplified in the work of G. W. F. Hegel and J. G. Herder--distinct from the Marxist tradition. While later commentators criticize Vygotsky's reliance on word meaning, arguing that…

Leitch, David G.

2011-01-01

306

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)

307

Instructional Design Processes and Traditional Colleges  

Science.gov (United States)

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

2010-01-01

308

Implementational Aspects of the Contourlet Filter Bank and Application in Image Coding  

Directory of Open Access Journals (Sweden)

Full Text Available This paper analyzed the implementational aspects of the contourlet filter bank (or the pyramidal directional filter bank (PDFB, and considered its application in image coding. First, details of the binary tree-structured directional filter bank (DFB are presented, including a modification to minimize the phase delay factor and necessary steps for handling rectangular images. The PDFB is viewed as an overcomplete filter bank, and the directional filters are expressed in terms of polyphase components of the pyramidal filter bank and the conventional DFB. The aliasing effect of the conventional DFB and the Laplacian pyramid to the directional filters is then considered, and the conditions for reducing this effect are presented. The new filters obtained by redesigning the PDFBs satisfying these requirements have much better frequency responses. A hybrid multiscale filter bank consisting of the PDFB at higher scales and the traditional maximally decimated wavelet filter bank at lower scales is constructed to provide a sparse image representation. A novel embedded image coding system based on the image decomposition and a morphological dilation algorithm is then presented. The coding algorithm efficiently clusters the significant coefficients using progressive morphological operations. Context models for arithmetic coding are designed to exploit the intraband dependency and the correlation existing among the neighboring directional subbands. Experimental results show that the proposed coding algorithm outperforms the current state-of-the-art wavelet-based coders, such as JPEG2000, for images with directional features.

Truong T. Nguyen

2009-02-01

309

Are Supernovae Recorded in Indigenous Astronomical Traditions?  

CERN Document Server

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

2014-01-01

310

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

311

Time Weight Update Model Based on the Memory Principle in Collaborative Filtering  

Directory of Open Access Journals (Sweden)

Full Text Available Collaborative filtering is the most widely used technology in the recommender systems. Existing collaborative filtering algorithms do not take the time factor into account. However, users’ interests always change with time, and traditional collaborative filtering cannot reflect the changes. In this paper, the change of users’ interests is considered as the memory process, and a time weight iteration model is designed based on memory principle. For a certain user, the proposed model introduces the time weight for each item, and updates the weight by computing the similarity with the items chosen in a recent period. In the recommend process, the weight will be applied to the prediction algorithm. Experimental results show that the modified algorithm can optimize the result of the recommendation in a certain extent, and performs better than traditional collaborative filtering.

Dan Li

2013-11-01

312

A double-filter method for nitrocellulose-filter binding: application to protein-nucleic acid interactions.  

OpenAIRE

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 ...

Wong, I.; Lohman, T. M.

1993-01-01

313

Vertical media bed filter and method of cleaning filter panels  

International Nuclear Information System (INIS)

A vertical media bed dust collector in which the media bed of a filter panel is rejuvenated when necessary by interrupting the gas flow through the panel, withdrawing the filter media from the panel] separating the agglomerated dust from the filter media, returing the filter media to the filter panel, and reestablishing the gas flow through the panel. The system further includes apparatus for removing collected dust from the deparating and recirculating surfaces of the media handling apparatus and also from the remote face of the filter panels before the cleaned gas is allowed to pass out of the collector so that the cleaned gas is not recontaminated by small amounts of dust adhering to those surfaces

314

RESEARCH ON SPATIAL FILTERS AND HOMOMORPHIC FILTERING METHODS  

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

2012-12-01

315

Particle Kalman Filtering: A Nonlinear Framework for Ensemble Kalman Filters  

OpenAIRE

Optimal nonlinear filtering consists of sequentially determining the conditional probability distribution functions (pdf) of the system state, given the information of the dynamical and measurement processes and the previous measurements. Once the pdfs are obtained, one can determine different estimates, for instance, the minimum variance estimate, or the maximum a posteriori estimate, of the system state. It can be shown that, many filters, including the Kalman filter (KF) and the particle f...

Hoteit, I.; Luo, X.; Pham, D-t; Moroz, Im; Simos, Te

2010-01-01

316

DSP Control of Line Hybrid Active Filter  

DEFF Research Database (Denmark)

Active Power Filters have been intensively explored in the past decade. Hybrid active filters inherit the efficiency of passive filters and the improved performance of active filters, and thus constitute a viable improved approach for harmonic compensation. In this paper a parallel hybrid filter is studied for current harmonic compensation. The hybrid filter is formed by a single tuned Le filter and a small-rated power active filter, which are directly connected in series without any matching transformer. Thus the required rating of the active filter is much smaller than a conventional standalone active filter. Simulation and experimental results obtained in laboratory confirmed the validity and effectiveness of the control.

Dan, Stan George; Benjamin, Doniga Daniel

2005-01-01

317

Experimental results of a single-phase shunt active filter prototype with different switching techniques  

OpenAIRE

This paper presents experimental results obtained with a developed single-phase shunt active power filter laboratory prototype operating with different switching techniques. This active filter can compensate harmonic currents and power factor in single-phase electric installations. Its power circuit is based on a two-leg IGBT inverter, with a single capacitor in the dc side, and an inductor in the ac side. Its control system is based on a simple stratagem that enables the use of the tradition...

Neves, Pedro; Pinto, J. G.; Pregitzer, Ricardo G.; Monteiro, Lui?s F. C.; Afonso, Joa?o L.; Sepu?lveda, Joa?o

2007-01-01

318

Grid filter design for a multi-megawatt medium-voltage voltage source inverter  

OpenAIRE

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

2010-01-01

319

Filter and Filter Bank Design for Image Texture Recognition  

Energy Technology Data Exchange (ETDEWEB)

The relevance of this thesis to energy and environment lies in its application to remote sensing such as for instance sea floor mapping and seismic pattern recognition. The focus is on the design of two-dimensional filters for feature extraction, segmentation, and classification of digital images with textural content. The features are extracted by filtering with a linear filter and estimating the local energy in the filter response. The thesis gives a review covering broadly most previous approaches to texture feature extraction and continues with proposals of some new techniques. 143 refs., 59 figs., 7 tabs.

Randen, Trygve

1997-12-31

320

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

321

Advances in Collaborative Filtering  

Science.gov (United States)

The collaborative filtering (CF) approach to recommenders has recently enjoyed much interest and progress. The fact that it played a central role within the recently completed Netflix competition has contributed to its popularity. This chapter surveys the recent progress in the field. Matrix factorization techniques, which became a first choice for implementing CF, are described together with recent innovations. We also describe several extensions that bring competitive accuracy into neighborhood methods, which used to dominate the field. The chapter demonstrates how to utilize temporal models and implicit feedback to extend models accuracy. In passing, we include detailed descriptions of some the central methods developed for tackling the challenge of the Netflix Prize competition.

Koren, Yehuda; Bell, Robert

322

Charcoal filter testing  

International Nuclear Information System (INIS)

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

323

Parzen Particle Filters  

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; Erdogmus, Deniz

2004-01-01

324

Converter and filter circuits  

CERN Document Server

This series of circuits provides designers with a quick source for converter and filter circuits. Why waste time paging through huge encyclopedias when you can choose the topic you need and select any of the specialized circuits sorted by application?This book in the series has 250-300 practical, ready-to-use circuit designs, with schematics and brief explanations of circuit operation. The original source for each circuit is listed in an appendix, making it easy to obtain additional information.Ready-to-use circuits.Grouped by application for easy look-up.Circuit sour

Graf, Rudolf F

1996-01-01

325

POLITICAL TRADITIONS: THE CONCEPT AND STRUCTURE  

Directory of Open Access Journals (Sweden)

Full Text Available The article refers to the theoretical aspects of the study of the political traditions phenomenon. The influence of traditional components of the political culture on the current political process is recognized in contemporary literature, but political traditions rarely become the original subject of a scientific research, which explains the vagueness of their interpretation and the need of their system understanding.The author analyzes existing interpretations of the concept "tradition", on which formulates the definition of "political traditions" as (1 a form of fixation for meaningful content of the nation’s socio-political experience and as (2 a mechanism of political-cultural continuity.The author identifies mental, behavioral and institutional levels in the structure of political traditions. Mental level consists of political symbols, myths and stereotypes, which form the image of political reality and authority, and values and norms, which affect the motivation of political behavior. Behavioral level includes models of behavior and patterns of action, such as political habits and rituals. Institutional level reflects historical features of interaction between branches of power and relations between the state and society.The author pays attention to the influence of structural elements of political traditions on the political consciousness and behavior of individuals and social groups. DOI: http://dx.doi.org/10.12731/2218-7405-2013-4-25

??????? ?????????? ??????

2013-05-01

326

POLITICAL TRADITIONS: THE CONCEPT AND STRUCTURE  

Directory of Open Access Journals (Sweden)

Full Text Available The article refers to the theoretical aspects of the study of the political traditions phenomenon. The influence of traditional components of the political culture on the current political process is recognized in contemporary literature, but political traditions rarely become the original subject of a scientific research, which explains the vagueness of their interpretation and the need of their system understanding. The author analyzes existing interpretations of the concept "tradition", on which formulates the definition of "political traditions" as (1 a form of fixation for meaningful content of the nation’s socio-political experience and as (2 a mechanism of political-cultural continuity. The author identifies mental, behavioral and institutional levels in the structure of political traditions. Mental level consists of political symbols, myths and stereotypes, which form the image of political reality and authority, and values and norms, which affect the motivation of political behavior. Behavioral level includes models of behavior and patterns of action, such as political habits and rituals. Institutional level reflects historical features of interaction between branches of power and relations between the state and society. The author pays attention to the influence of structural elements of political traditions on the political consciousness and behavior of individuals and social groups.

Mamina Natalia Alekseevna

2013-04-01

327

The Decline of Traditional Banking Activities  

Directory of Open Access Journals (Sweden)

Full Text Available The decline of traditional banking activities raise the issue of efficiency of financial stability, in terms ofquantitative and qualitative aspects – the increasing danger of banking failures as well as of susceptibility due toincreased propensity of banking institutions to assume additional to risks either in the form of riskier loans offer orengaging in other "non-traditional" financial activities which give a promise for greater profitability, but also higherrisks. Non-traditional activities of banking as financial products dealers (financial derivatives, generate an increasingrisks and vulnerabilities in the form of moral hazard issues. That is the reason why and these activities should beregulated as well as are the traditional activities. Challenges posed by the decline of traditional banking activities istwofold: the stability of the banking system must be maintained, while the banking system needs to be restructured toachieve financial stability in the long run. One possible way is an appropriate regulatory framework to encourage atransition period of changing the structure of banking activity(reduction of traditional activities and expanding nontraditional activities to enable banking institutions to perform a deep methodic analysis of non traditional activities,oriented to the financial banking efficiency.

Gabriela Cornelia Piciu

2011-05-01

328

A taxonomy fuzzy filtering approach  

Directory of Open Access Journals (Sweden)

Full Text Available 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 operators to yield the belief to the filter. In our study, Support Vector Machines and Naïve Bayes classifiers were used to provide topic probabilities. Aggregation of topic probabilities based on fuzzy logic operators was found to improve filtering performance on the Renters text corpus, as compared to the use of their Boolean counterparts. Finally, we deployed a filtering system on the web using a sample taxonomy of the Open Directory Project.

Vrettos S.

2003-01-01

329

Wavelength Filters in Fibre Optics  

CERN Document Server

Wavelength filters constitute an essential element of fibre-optic networks. This book gives a comprehensive account of the principles and applications of such filters, including their technological realisation. After an introductory chapter on wavelength division multiplexing in current and future fibre optic networks follows a detailed treatment of the phase characteristics of wavelength filters, a factor frequently neglected but of significant importance at high bit rates. Subsequent chapters cover three-dimensional reflection of gratings, arrayed waveguide gratings, fibre Bragg gratings, Fabry-Perot filters, dielectric multilayer filters, ring filters, and interleavers. The book explains the relevant performance parameters, the particular advantages and shortcomings of the various concepts and components, and the preferred applications. It also includes in-depth information on the characteristics of both commercially available devices and those still at the R&D stage. All chapters are authored by inter...

Venghaus, Herbert

2006-01-01

330

Darut Tauhid: Modernizing a Pesantren Tradition  

Directory of Open Access Journals (Sweden)

Full Text Available This study presents a case study of the Daarut Tauhiid Pesantren in Bandung, West Java, which represents an emerging trend in recent years in Indonesia, that is, the growing popularity of what we refer to here as the 'virtual pesantren'. Employing such a term in relation to the pesantren tradition - a tradition that has existed in Indonesia for many centuries - palpably indicates the changing nature of the tradition.Copyright (c 2014 by SDI. All right reserved.DOI: 10.15408/sdi.v12i3.583

Zaki Nur'aeni

2005-12-01

331

Multi-filter spectrophotometry simulations  

Science.gov (United States)

To complement both the multi-filter observations of quasar environments described in these proceedings, as well as the proposed UBC 2.7 m Liquid Mirror Telescope (LMT) redshift survey, we have initiated a program of simulated multi-filter spectrophotometry. The goal of this work, still very much in progress, is a better quantitative assessment of the multiband technique as a viable mechanism for obtaining useful redshift and morphological class information from large scale multi-filter surveys.

Callaghan, Kim A. S.; Gibson, Brad K.; Hickson, Paul

1993-01-01

332

Sample-whitened matched filters  

OpenAIRE

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

2010-01-01

333

Continuous RPD electron energy filter  

International Nuclear Information System (INIS)

An electron energy filter based on the retarding potential difference method has been described. As opposed to the classical, pulsed RPD filter, the retarding potentials are applied at two spatially separated electrodes. The retarding potentials have continuous, i.e. constant in time values. As a result of that, the exit beam has continual in time characteristics. This geometry resulted in slightly superior resolution than in case of pulsed RPD filter. (author)

334

Digital filtering in nuclear medicine  

International Nuclear Information System (INIS)

Digital filtering is a powerful mathematical technique in computer analysis of nuclear medicine studies. The basic concepts of object-domain and frequency-domain filtering are presented in simple, largely nonmathematical terms. Computational methods are described using both the Fourier transform and convolution techniques. The frequency response is described and used to represent the behavior of several classes of filters. These concepts are illustrated with examples drawn from a variety of important applications in nuclear medicine

335

Resonant grating filters for microsystems  

OpenAIRE

In the present work we report on the design and characterization of a tunable optical filter for use in a compact add-drop multiplexer. The optical filter is a resonant grating filter (RGF) consisting of a planar waveguide and a grating parallel to the surface. A resonance occurs when the incoming light is diffracted by the grating and matches a mode in the waveguide. Numerous aspects of the modeling, design optimization, fabrication tolerances and characterization are addressed. A particular...

Niederer, Guido; Herzig, Hans-peter

2004-01-01

336

HEPA filter performance comparative study  

International Nuclear Information System (INIS)

Current products such as HEPA filters made without separators, with tapered separators and with mini separators have raised many questions for the Nuclear Ventilation System Design Engineer and/or the end user. The principal objective of this investigation is to report HEPA filter performance data and to compare the effectiveness of the various type HEPA filters for use in Nuclear Ventilation Systems with all tests run on the same equipment and under the same controlled conditions

337

Note: Cryogenic coaxial microwave filters  

Energy Technology Data Exchange (ETDEWEB)

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.

Tancredi, G.; Meeson, P. J. [Department of Physics, Royal Holloway, University of London, Egham TW20 0EX (United Kingdom); Schmidlin, S. [Department of Physics, Royal Holloway, University of London, Egham TW20 0EX (United Kingdom); National Physical Laboratory, Hampton Road, Teddington TW11 0LW (United Kingdom)

2014-02-15

338

Tunable Imaging Filters in Astronomy  

OpenAIRE

While tunable filters are a recent development in night time astronomy, they have long been used in other physical sciences, e.g. solar physics, remote sensing and underwater communications. With their ability to tune precisely to a given wavelength using a bandpass optimized for the experiment, tunable filters are already producing some of the deepest narrowband images to date of astrophysical sources. Furthermore, some classes of tunable filters can be used in fast telesco...

Bland-hawthorn, J.

2000-01-01

339

Shunt Active Filter in Damping Harmonics Propagation  

OpenAIRE

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...

Berbaoui, B.; Rahli, M.; Meslem, Y.; Tedjini, H.

2010-01-01

340

Nanoparticle optical notch filters  

Science.gov (United States)

Developing novel light blocking products involves the design of a nanoparticle optical notch filter, working on the principle of localized surface plasmon resonance (LSPR). These light blocking products can be used in many applications. One such application is to naturally reduce migraine headaches and light sensitivity. Melanopsin ganglion cells present in the retina of the human eye, connect to the suprachiasmatic nucleus (SCN-the body's clock) in the brain, where they participate in the entrainment of the circadian rhythms. As the Melanopsin ganglion cells are involved in triggering the migraine headaches in photophobic patients, it is necessary to block the part of visible spectrum that activates these cells. It is observed from the action potential spectrum of the ganglion cells that they absorb light ranging from 450-500nm (blue-green part) of the visible spectrum with a ?max (peak sensitivity) of around 480nm (blue line). Currently prescribed for migraine patients is the FL-41 coating, which blocks a broad range of wavelengths, including wavelengths associated with melanopsin absorption. The nanoparticle optical notch filter is designed to block light only at 480nm, hence offering an effective prescription for the treatment of migraine headaches.

Kasinadhuni, Pradeep Kumar

341

Ozone removal by HVAC filters  

Science.gov (United States)

Residential and commercial HVAC filters that have been loaded with particles during operation in the field can remove ozone from intake or recirculated air. However, knowledge of the relative importance of HVAC filters as a removal mechanism for ozone in residential and commercial buildings is incomplete. We measured the ozone removal efficiencies of clean (unused) fiberglass, clean synthetic filters, and field-loaded residential and commercial filters in a controlled laboratory setting. For most filters, the ozone removal efficiency declined rapidly but converged to a non-zero (steady-state) value. This steady-state ozone removal efficiency varied from 0% to 9% for clean filters. The mean steady-state ozone removal efficiencies for loaded residential and commercial filters were 10% and 41%, respectively. Repeated exposure of filters to ozone following a 24-h period of no exposure led to a regeneration of ozone removal efficiency. Based on a theoretical scaling analysis of mechanisms that are involved in the ozone removal process, we speculate that the steady-state ozone removal efficiency is limited by reactant diffusion out of particles, and that regeneration is due to internal diffusion of reactive species to sites available to ozone for reaction. Finally, by applying our results to a screening model for typical residential and commercial buildings, HVAC filters were estimated to contribute 22% and 95%, respectively, of total ozone removal in HVAC systems.

Zhao, P.; Siegel, J. A.; Corsi, R. L.

342

Cryptographically Secure Bloom-Filters  

OpenAIRE

In this paper, we propose a privacy-preserving variant of Bloom-filters. The Bloom-filter has many applications such as hash-based IP-traceback systems and Web cache sharing. In some of those applications, equipping the Bloom-filter with the privacy-preserving mechanism is crucial for the deployment. In this paper, we propose a cryptographically secure privacy-preserving Bloom-filter protocol. We propose such two protocols based on blind signatures and oblivious pseudorandom functions, respe...

Ryo Nojima; Youki Kadobayashi

2009-01-01

343

Optimization of integrated polarization filters  

CERN Document Server

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

2014-01-01

344

Performance evaluation of a loeb-eiber mass filter at 1 torr.  

Science.gov (United States)

The Loeb-Eiber mass filter is best operated at relatively high pressures-such as 1 Torr-where collisional dampening of ions up to the mass filter thermalizes the ions' kinetic energy, which is a requirement for effective filtering. The inter-electrode gaps of ~8 ?m require rf amplitudes on the order of 0-5 V p-p at approximately 50 MHz to achieve mass filtering up to m/z 40. Mass filtering between the 25-?m diameter wires, therefore, takes place on time frames less than the collision frequency at ~1 Torr. The low power and high pressure capabilities of the Loeb-Eiber mass filter make it ideally suited for miniaturization, where power and space are a premium. In the present work, a Loeb-Eiber mass filter was constructed using commercial silicon-on-insulator (SOI) microfabrication techniques. Ions transmitting through the chip-based Loeb-Eiber mass filter were characterized in real time using a traditional linear quadrupole mass analyzer in series with the Loeb-Eiber mass filter. The new hybrid instrument has enabled us to verify several important claims regarding the operation of the Loeb-Eiber mass filter: (1) that ions can be effectively filtered at ~1 Torr, (2) that for ions of a fixed mass-to-charge ratio, the ion transmission current decreases linearly with increasing rf amplitude on the Loeb-Eiber mass filter, (3) that the cutoff voltage at which all ions of a particular m/z value are effectively blocked is linearly related to mass-to-charge, and (4) that square waveforms can filter ions more effectively than sinusoidal waveforms for a given peak-to-peak rf amplitude. PMID:25527329

Hoffmann, William D; Jin, Feng; Pedder, Randall E; Taormina, Christopher; Jackson, Glen P

2015-02-01

345

MARKETING OF TRADITIONAL PRODUCT IN TRANSYLVANIA  

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.

M. MATIUTI

2013-07-01

346

Sustainable architecture in the traditional Iranian homes  

Energy Technology Data Exchange (ETDEWEB)

With the coming shortage of fossil fuels it is important to develop energy efficient buildings to reduce both energy consumption and pollution at the same time. In Iran, traditional homes have been built in a sustainable manner to withstand the high climate diversity of the country. The aim of this paper is to present the different methods used in Iranian traditional architecture. Among the architectural principles is appropriate orientation of the building to allow the capture of solar energy and at the same time protect against the cold wind. In addition, indigenous materials were used in the constructions to provide the highest degree of comfort possible with minimal damage to the environment. Finally, Iranian traditional architecture took advantage of the soil's constant temperature by building a Shvadan which is an underground space beneath the house. This article highlighted the different Iranian traditional methods which can create a sustainable architecture.

Rezaei, Davood; Niloufari, Morteza; Sadegh Falahat, Mohammad [Zanjan University (Iran, Islamic Republic of)], email: d_rezaei@znu.ac.ir, email: mortezagharibeh@yahoo.com, email: safalahat@yahoo.com

2011-07-01

347

Protecting traditional knowledge from the grassroots up  

Energy Technology Data Exchange (ETDEWEB)

For indigenous peoples round the world, traditional knowledge based on natural resources such as medicinal herbs forms the core of culture and identity. But this wealth of knowledge is under pressure. Indigenous communities are increasingly vulnerable to eviction, environmental degradation and outside interests eager to monopolise control over their traditional resources. Intellectual property rights such as patents, however, sit uneasily with traditional knowledge. Their commercial focus wars with fundamental indigenous principles such as resource access and sharing. Local customary law offers a better fit, and findings in China, India, Kenya, Panama and Peru show how this pairing can work in practice. The research has identified common elements, and key differences, in customary law that should be informing policy on traditional knowledge and genetic resources.

Arugomedo, Alejandro [ANDES Association (Peru); Pant, Ruchi [Ecoserve (India); Vedavathy, S. [Herbal Folklore Reseach Centre (India); Munyi, Peter [International Centre of Insect Physiology and Ecology (Kenya); Mutta, Doris [Kenya Forestry Research Institute (Kenya); Herrera, Heracilo [Dobbo Yala Foundation (Panama); Song, Yinching; Li, Jingsong [Centre of Chinese Agricultural Policy (China); Swiderska, Krystyna

2009-06-15

348

The Reformed tradition as public theology  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english 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 l [...] inked. 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.

349

Subjugating Knowledges – Transmissional Traditions in School Education  

Directory of Open Access Journals (Sweden)

Full Text Available In general, knowledge and tradition are credited with positive connotations. Popular definitions of knowledge carry surplus meaning evaluated even more positively than the attributes stereotypically assigned to tradition. In this article I intend to carry out preliminary recognition of the semiotics of what can be defined as a traditional model of a lesson, “reading into” the accepted definitions of knowledge, and teachers’ and students’ roles at school. In this way, I will try to identify the basic sources of such definitions. Later, I will reconstruct the selective effects of the inert maintenance of the concepts of knowledge and of the statuses and principles of the roles of teachers and students. Finally, I will indicate hypothetical reasons for why “the tradition of transmission” is maintained despite its disquieting results.

Dorota Klus-Sta?ska

2013-07-01

350

Intrusions of Modernity on a Traditional Culture.  

Science.gov (United States)

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

1991-01-01

351

Bridging the ensemble Kalman filter and particle filters  

Energy Technology Data Exchange (ETDEWEB)

The nonlinear filtering problem occurs in many scientific areas. Sequential Monte Carlo solutions with the correct asymptotic behavior such as particle filters exist but they are computationally too expensive when working with high-dimensional systems. The ensemble Kalman filter is a more robust method that has shown promising results with a small sample size but the samples are not guaranteed to come from the true posterior distribution. By approximating the model error with Gaussian kernels we get the advantage of both a Kalman correction and a weighting step. The resulting Gaussian mixture filter has the advantage of both a local Kalman type correction and the weighting/re sampling step of a particle filter. The Gaussian mixture approximation relies on a tunable bandwidth parameter which often has to be kept quite large in order to avoid weight collapse in high dimensions. As a result, the Kalman correction is too large to capture highly non-Gaussian posterior distributions. In this paper we have extended the Gaussian mixture filter (Hoteit et al., 2008b) and also made the connection to particle filters more transparent. In particular we introduce a tuning parameter for the importance weights. In the last part of the paper we have performed a simulation experiment with the Lorenz40 model where our method has been compared to the EnKF and a full implementation of a particle filter. The results clearly indicate that the new method has advantages compared to the standard EnKF. (Author)

Stordal, Andreas Stoerksen; Karlsen, Hans A.; Naevdal, Geir; Skaug, Hans J.; Valles, Brice

2009-12-15

352

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 a very demanding and significance role in this era of internet information and of course e commerce age. Collaborative filtering predicts user preferences from past user behaviour or user-item relationships. Though it has many advantages it also has some limitations such as sparsity, scalability, accuracy, cold start problem etc. In this paper we proposed a method that helps in reducing sparsity to enhance recommendation accuracy. We developed fuzzy inference rules which is easily to implement and also gives better result. A comparison experiment is also performing with two previous methods, Traditional Collaborative Filtering (TCF and Hybrid User Model Technique (HUMCF.

Atisha Sachan

2013-06-01

353

Traditional Chinese Medicine for Senile Dementia  

OpenAIRE

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

2012-01-01

354

Two traditional African settlements - context and configuration  

OpenAIRE

Vernacular African settlements and buildings are widely appreciated for their human scale, aesthetic clarity and harmony with nature. But this appreciation appears to be limited to their iconic and picturesque qualities, and there seems to be little understanding of the value of these architectural traditions as products of historical, ecological, cultural and economic circumstances. This study compares a traditional Tonga compound at Siamundela, southern Zambia with a Banoka village near Khw...

Steyn, Gerald; Roodt, Andre?

2003-01-01

355

Traditional and modern medicine working in tandem  

OpenAIRE

Because of the many problem relating to health care delivery in Africa, it is becoming apparent that neither the exclusive/monopolistic nor the tolerant legislative systems should be tolerated any longer. Especially since the Alma Ata Conference held by the WHO/UNICEF there has been growing impetus towards either inclusive/parallel (the beneficial co-existence of traditional and modern medical systems), or integrated systems. Although the idea of making traditional and modern medicine work in...

Pretorius, E.

1991-01-01

356

Massage Therapy in Iranian Traditional Medicine  

OpenAIRE

Background and Aim: Massage training and how the body is influenced by massage are common issues which are seriously under study and discussion in Iranian traditional medicine. Iranian physicians considered motion and massage as major principles of health maintenance.In this study, we examined the available literature of traditional medicine to evaluate location, purpose and use of massage therapy in Iranian medicine in comparison with other popular conventional styles.The aim of Iranian mass...

Amir-Mohammad Jaladat; Majid Nimrouzi; Mehrdad Karimi; Mamak Hashemi; Mehdi Falah; Fatemeh Attarzadeh

2012-01-01

357

Method for studying traditional Chinese compound prescription  

OpenAIRE

Treatment with traditional Chinese medicinal composite is one of the most important characteristics of traditional Chinese medicine (TCM). Studying material base of TCM composite and its mechanism is a key to modernizing the industry of Chinese medicinal herbs. The research for TCM composite can be carried out from many different angles?including multiple components, multiple actions, multiple levels and multiple targets. Such a way to study TCM composite will be beneficial to improving the...

Xu, Jian-yang

2005-01-01

358

Cultural anthropology of traditional Chinese medicine  

OpenAIRE

Abstract: Biological, psychological and sociological model of medicine substantializes the old model lacking the social humane attributes. The new medical model makes people take medical anthropology into research and highly evaluate traditional medical system. Cultural anthropology of traditional Chinese medicine (TCM) is part of medical anthropology with three major characteristics: wide research scope, specificity, and integration. It has developed its own research methods, such as field i...

Wan, Xia; Liu, Jian-ping

2008-01-01

359

HAZARDS MANAGEMENT FOR TRADITIONAL FOOD PRODUCTS  

OpenAIRE

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

2013-01-01

360

Music transcription within Irish traditional music  

OpenAIRE

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...

Gainza, Mikel

2006-01-01

361

Mambila traditional religion : Sua in Somie  

OpenAIRE

This work is an analysis of Mambila religion based on fieldwork in Somie village, Cameroon. An ethnographic and historical introduction to the Mambila is followed by an account of their religious concepts. It is argued that, despite their adherence to Christianity (and to Islam), traditional practices continue to be of great importance in everyday life. In order to examine traditional practice descriptions are given of divination and oath-taking rites. Translated transcripts...

Zeitlyn, David

1990-01-01

362

Application of DFT Filter Banks and Cosine Modulated Filter Banks in Filtering  

Science.gov (United States)

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.

1994-01-01

363

Bridging the ensemble Kalman filter and particle filters: the adaptive Gaussian mixture filter  

OpenAIRE

The nonlinear filtering problem occurs in many scientific areas. Sequential Monte Carlo solutions with the correct asymptotic behavior such as particle filters exist, but they are computationally too expensive when working with high-dimensional systems. The ensemble Kalman filter (EnKF) is a more robust method that has shown promising results with a small sample size, but the samples are not guaranteed to come from the true posterior distribution. By approximating the model error with a Gauss...

Stordal, Andreas Størksen; Karlsen, Hans A.; Nævdal, Geir; Skaug, Hans J.; Valle?s, Brice

2010-01-01

364

Bridging the ensemble Kalman filter and particle filters:the adaptive Gaussian mixture filter  

OpenAIRE

The nonlinear filtering problem occurs in many scientific areas. Sequential Monte Carlo solutions with the correct asymptotic behavior such as particle filters exist, but they are computationally too expensive when working with high-dimensional systems. The ensemble Kalman filter (EnKF) is a more robust method that has shown promising results with a small sample size, but the samples are not guaranteed to come from the true posterior distribution. By approximating the model error with a Gauss...

Stordal, Andreas Størksen; Karlsen, Hans A.; Nævdal, Geir; Skaug, Hans J.; Valle?s, Brice

2010-01-01

365

Position USBL/DVL Sensor-based Navigation Filter in the presence of Unknown Ocean Currents  

CERN Document Server

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

2010-01-01

366

Particle Kalman Filtering: A Nonlinear Framework for Ensemble Kalman Filters  

Science.gov (United States)

Optimal nonlinear filtering consists of sequentially determining the conditional probability distribution functions (pdf) of the system state, given the information of the dynamical and measurement processes and the previous measurements. Once the pdfs are obtained, one can determine different estimates, for instance, the minimum variance estimate, or the maximum a posteriori estimate, of the system state. It can be shown that, many filters, including the Kalman filter (KF) and the particle filter (PF), can be derived based on this sequential Bayesian estimation framework. In this contribution, we present a Gaussian mixture-based framework, called the particle Kalman filter (PKF), and discuss how the different EnKF methods can be derived as simplified variants of the PKF. We also discuss approaches to reducing the computational burden of the PKF in order to make it suitable for complex geosciences applications. We use the strongly nonlinear Lorenz-96 model to illustrate the performance of the PKF.

Hoteit, Ibrahim; Luo, Xiaodong; Pham, Dinh-Tuan; Moroz, Irene M.

2010-09-01

367

Testing Dual Rotary Filters - 12373  

International Nuclear Information System (INIS)

The Savannah River National Laboratory (SRNL) installed and tested two hydraulically connected SpinTekR Rotary Micro-filter units to determine the behavior of a multiple filter system and develop a multi-filter automated control scheme. Developing and testing the control of multiple filters was the next step in the development of the rotary filter for deployment. The test stand was assembled using as much of the hardware planned for use in the field including instrumentation and valving. The control scheme developed will serve as the basis for the scheme used in deployment. The multi filter setup was controlled via an Emerson DeltaV control system running version 10.3 software. Emerson model MD controllers were installed to run the control algorithms developed during this test. Savannah River Remediation (SRR) Process Control Engineering personnel developed the software used to operate the process test model. While a variety of control schemes were tested, two primary algorithms provided extremely stable control as well as significant resistance to process upsets that could lead to equipment interlock conditions. The control system was tuned to provide satisfactory response to changing conditions during the operation of the multi-filter system. Stability was maintained through the startup and shutdown of one of the filter units while the second was still in operation. The equipment selected for deployment, including the concentrate discharge control valve, the pressure transmitters, and flow meters, performed well. Automation of the valve control integrated well with the control scheme and when used in concert with the other control variables, allowed automated control of the dual rotary filter system. Experience acquired on a multi-filter system behavior and with the system layout during this test helped to identify areas where the current deployment rotary filter installation design could be improved. Completion of this testing provides the necessary information on the control and system behavior that will be used in deployment on actual waste. (authors)

368

Compressed sensing & sparse filtering  

CERN Document Server

This book is aimed at presenting concepts, methods and algorithms ableto cope with undersampled and limited data. One such trend that recently gained popularity and to some extent revolutionised signal processing is compressed sensing. Compressed sensing builds upon the observation that many signals in nature are nearly sparse (or compressible, as they are normally referred to) in some domain, and consequently they can be reconstructed to within high accuracy from far fewer observations than traditionally held to be necessary. Apart from compressed sensing this book contains other related app

Carmi, Avishy Y; Godsill, Simon J

2013-01-01

369

Particle Filtering for Quantized Sensor Information  

OpenAIRE

The implication of quantized sensor information on filtering problems is studied. The Cramer-Rao lower bound (CRLB) is derived for estimation and filtering on quantized data. A particle filter (PF) algorithm that approximates the optimal nonlinear filter is provided, and numerical experiments show that the PF attains the CRLB, while second-order optimal Kalman filter (KF) approaches can perform quite bad.

Karlsson, Rickard; Gustafsson, Fredrik

2005-01-01

370

Subjective Collaborative Filtering  

CERN Document Server

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

2011-01-01

371

3D noise power spectrum applied on clinical MDCT scanners: effects of reconstruction algorithms and reconstruction filters  

Science.gov (United States)

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.

2011-03-01

372

AER image filtering  

Science.gov (United States)

Address Event Representation (AER) is an emergent neuromorphic interchip communication protocol that allows real-time virtual massive connectivity among huge number of neurons located on different chips.[1] By exploiting high speed digital communication circuits (with nano-seconds timing), synaptic neural connections can be time multiplexed, while neural activity signals (with mili-seconds timings) are sampled at low frequencies. Neurons generate "events" according to their activity levels. That is, more active neurons generate more events per unit time and access the interchip communication channel more frequently than neurons with low activity. In Neuromorphic system development, AER brings some advantages to develop real-time image processing system: (1) AER represents the information like time continuous stream not like a frame; (2) AER sends the most important information first (although this depends on the sender); (3) AER allows to process information as soon as it is received. When AER is used in artificial vision field, each pixel is considered like a neuron, so pixel's intensity is represented like a sequence of events; modifying the number and the frequency of these events, it is possible to make some image filtering. In this paper we present four image filters using AER: (a) Noise addition and suppression, (b) brightness modification, (c) single moving object tracking and (d) geometrical transformations (rotation, translation, reduction and magnification). For testing and debugging, we use USB-AER board developed by Robotic and Technology of Computers Applied to Rehabilitation (RTCAR) research group. This board is based on an FPGA, devoted to manage the AER functionality. This board also includes a micro-controlled for USB communication, 2 Mbytes RAM and 2 AER ports (one for input and one for output).

Gómez-Rodríguez, F.; Linares-Barranco, A.; Paz, R.; Miró-Amarante, L.; Jiménez, G.; Civit, A.

2007-05-01

373

Consistency checks for particle filters  

OpenAIRE

An "inconsistent" particle filter produces - in a statistical sense - larger estimation errors than predicted by the model on which the filter is based. Two test variables are introduced that allow the detection of inconsistent behavior. The statistical properties of the variables are analyzed. Experiments confirm their suitability for inconsistency detection.

Heijden, F.

2006-01-01

374

X-band preamplifier filter  

Science.gov (United States)

A low-loss bandstop filter designed and developed for the Deep Space Network's 34-meter high-efficiency antennas is described. The filter is used for protection of the X-band traveling wave masers from the 20-kW transmitter signal. A combination of empirical and theoretical techniques was employed as well as computer simulation to verify the design before fabrication.

Manshadi, F.

1986-01-01

375

The double well mass filter  

Energy Technology Data Exchange (ETDEWEB)

Various mass filter concepts based on rotating plasmas have been suggested with the specific purpose of nuclear waste remediation. We report on a new rotating mass filter combining radial separation with axial extraction. The radial separation of the masses is the result of a “double-well” in effective radial potential in rotating plasma with a sheared rotation profile.

Gueroult, Renaud; Fisch, Nathaniel J. [Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Rax, Jean-Marcel [Laboratoire d' optique appliquée-LOA, Ecole Polytechnique, Chemin de la Hunière, 91761 Palaiseau Cedex (France)

2014-02-15

376

Narrow-Band Microwave Filters  

OpenAIRE

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).

Strizhachenko, A. V.; Zvyagintsev, A. A.; Shul’ga, S. N.; Chizhov, V. V.

2010-01-01

377

Filter desulfation system and method  

Energy Technology Data Exchange (ETDEWEB)

A method of removing sulfur from a filter system of an engine includes continuously passing an exhaust flow through a desulfation leg of the filter system during desulfation. The method also includes sensing at least one characteristic of the exhaust flow and modifying a flow rate of the exhaust flow during desulfation in response to the sensing.

Lowe, Michael D. (Metamora, IL); Robel, Wade J. (Normale, IL); Verkiel, Maarten (Metamora, IL); Driscoll, James J. (Dunlap, IL)

2010-08-10

378

Digital Filters Using Identical Blocks  

Directory of Open Access Journals (Sweden)

Full Text Available Improved response of non-recursive digital filters is achieved using Amplitude Change Functions (ACFs on a prototype filter. A generalized ACF with interesting properties is suggested. Methods for achieving variable cut-off frequency and frequency transformation are explained. A modular hardware implementation is also presented.

S. C. Dutta

2014-01-01

379

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)

380

Sintered composite medium and filter  

Science.gov (United States)

A particulate filter medium is formed of a sintered composite of 0.5 micron diameter quartz fibers and 2 micron diameter stainless steel fibers. A preferred composition is about 40 vol. % quartz and about 60 vol. % stainless steel fibers. The media is sintered at about 1100.degree. C. to bond the stainless steel fibers into a cage network which holds the quartz fibers. High filter efficiency and low flow resistance are provided by the smaller quartz fibers. High strength is provided by the stainless steel fibers. The resulting media has a high efficiency and low pressure drop similar to the standard HEPA media, with tensile strength at least four times greater, and a maximum operating temperature of about 550.degree. C. The invention also includes methods to form the composite media and a HEPA filter utilizing the composite media. The filter media can be used to filter particles in both liquids and gases.

Bergman, Werner (Pleasanton, CA)

1987-01-01

381

Filtered Backprojection Reconstruction with Depth-Dependent Filtering.  

Science.gov (United States)

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. PMID:20585466

Dennerlein, Frank; Kunze, Holger; Noo, Frédéric

2010-02-01

382

Traditional Chinese food technology and cuisine.  

Science.gov (United States)

From ancient wisdom to modern science and technology, Chinese cuisine has been established from a long history of the country and gained a global reputation of its sophistication. Traditional Chinese foods and cuisine that exhibit Chinese culture, art and reality play an essential role in Chinese people's everyday lives. Recently, traditional Chinese foods have drawn a great degree of attention from food scientists and technologists, the food industry, and health promotion institutions worldwide due to the extensive values they offer beyond being merely another ethnic food. These traditional foods comprise a wide variety of products, such as pickled vegetables, salted fish and jellyfish, tofu and tofu derived products, rice and rice snack foods, fermented sauces, fish balls and thousand-year-old eggs. An overview of selected popular traditional Chinese foods and their processing techniques are included in this paper. Further development of the traditional techniques for formulation and production of these foods is expected to produce economic, social and health benefits. PMID:15228981

Li, Jian-rong; Hsieh, Yun-Hwa P

2004-01-01

383

Deconstructing Tradition in Japanese Music : A Study of Shakuhachi, Historical Authenticity and Transmission of Tradition  

OpenAIRE

In the present study I examine the vertical bamboo flute shakuhachi, as an example of how a tradition can be constructed. There are two main issues: the historical authenticity of the believed origins and development of the shakuhachi tradition, and how the transmission of this tradition is conducted. The first main issue is concerned with how a legendary origin, probably constructed in the late seventeenth century, was disproved in early twentieth-century studies. According to this legendary...

Linder, Gunnar Jinmei

2012-01-01

384

An epistemological reflection on the relevance of monastic traditions for retreat in the Dutch Reformed tradition  

OpenAIRE

The article focuses on retreat as a relatively new phenomenon in the Dutch Reformed tradition. Retreat is viewed as "communicative action". The aim of the article is firstly to explore epistemological theories in the postmodern paradigm. These theories provide a mental framework for the identification of a research model and a related methodology by means of which the relevance of monastic traditions for retreat in the Reformed tradition can be discovered. The identification o...

Schutte, C. H.; Yolanda Dreyer

2009-01-01

385

Optisches Filter und ein Verfahren zur Herstellung eines optischen Filters  

OpenAIRE

DE 102009021936 A1 UPAB: 20101203 NOVELTY - The variable optical filter for optical spectroscopy, for the analysis of electromagnetic radiation, has two partially-transparent mirrors (1a,1b) and a pliable spacer holder (7,15) of an electro-active material between them. The gap (20a) between the mirrors is set according to the voltage (U) applied to the optical filter. USE - The optical filter is for optical spectroscopy in the analysis of electromagnetic radiation from UV to medium infra red,...

Schenk, H.; Sandner, T.; Schirrmann, C.; Costache, F.

2009-01-01

386

Block implementation of adaptive digital filters  

International Nuclear Information System (INIS)

Block digital filtering involves the calculation of a block or finite set of filter outputs from a block of input values. This paper presents a block adaptive filtering procedure in which the filter coefficients are adjusted once per each output block in accordance with a generalized least mean-square (LMS) algorithm. Analyses of convergence properties and computational complexity show that the block adaptive filter permits fast implementations while maintaining performance equivalent to that of the widely used LMS adaptive filter

387

A Gaussian mixture ensemble transform filter  

OpenAIRE

We generalize the popular ensemble Kalman filter to an ensemble transform filter where the prior distribution can take the form of a Gaussian mixture or a Gaussian kernel density estimator. The design of the filter is based on a continuous formulation of the Bayesian filter analysis step. We call the new filter algorithm the ensemble Gaussian mixture filter (EGMF). The EGMF is implemented for three simple test problems (Brownian dynamics in one dimension, Langevin dynamics i...

Reich, Sebastian

2011-01-01

388

Image Filtering Methods for Biomedical Applications  

OpenAIRE

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

2011-01-01

389

High frequency model of EMI filter  

OpenAIRE

The EMI filters are usually used for suppression of electromagnetic conducted interference of range 9 kHz-30 MHz. The efficiency of electromagnetic interference filter is described by attenuation characteristics. The value of attenuation of EMI filter depends on main parameters of filter’s elements and its parasitic parameters. Therefore the high frequency model of electromagnetic interference filter is analyzed in this paper.

Szymon Pasko; Boguslaw Grzesik

2012-01-01

390

A Gaussian mixture ensemble transform filter  

CERN Document Server

We generalize the popular ensemble Kalman filter to an ensemble transform filter where the prior distribution can take the form of a Gaussian mixture. The design of the filter is based on a continuous formulation of the Bayesian filter analysis step. We call the new filter algorithm the ensemble Gaussian mixture filter (EGMF). The EGMF is implemented for two simple test problems (Brownian dynamics in one dimension and a modified Lorenz-96 model).

Reich, Sebastian

2011-01-01

391

LMS order statistic filters adaptation by backpropagation  

OpenAIRE

A novel class of nonlinear adaptive filters based on order statistics is presented. An LMS algorithm for their adaptation is proposed. This algorithm is essentially a backpropagation algorithm for the adaptation of coefficients that are used before data sorting. The nonlinear filters that can become adaptive by the techniques presented in this paper are the median hybrid filter, the general nonlinear filter structure, the L-filters and the Ll-filters.

Pitas, I.; Vougioukas, S.

2010-01-01

392

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.

Huang Bo

2010-01-01

393

The ?Guslar?: Individual identity and tradition  

Directory of Open Access Journals (Sweden)

Full Text Available The subject of this paper is the relation between individual and collective identity within the folk-music tradition, from the perspective of ethnomusicology. Solo folk musicians have more latitude than those who perform in ensembles. They are more independent in developing their own style. As an example of this intermingling of individual and traditional styles, we have chosen Branko Perovi?, ?guslar? (a singer of epic songs who accompanies himself on the ?gusle? - currently one of the very best. Both his extraordinary vocal qualities and his unique combination of temperament and emotions have enabled Perovi? to develop an original performing style. By comparing the regional, Montenegrin style of gusle-playing (of which Perovi? is a representative with his personal style, we have established certain corresponding structures regarding a few basic analytical parameters: musical form at the macro-level, tonal structure, and harmonic structure. Individual characteristics are to be found in melodic patterns, dynamics, agogics and ornaments, and to a certain extent, in rhythm. Although Perovi? is considered to be an ?innovator? among folk musicians, taking a dynamic approach to tradition, he is, however, well received and highly rated in folk music circles, which is proof of his successful communication with his audience. His reputation and influence on other gusle-players makes him a worthy link in the chain of epic tradition. His performance underlines the importance of the connection between traditional music and society, within which he develops his own style according to his capacities and inclinations, although constantly referring to the functional and aesthetic criteria of his cultural environment in which he performs. This is how adopted models are being reshaped by both individual artistic style and the current cultural pattern of a given community. The individual identity (of the musician is in constant interaction with those of his/her ancestors and contemporaries. The extraordinary, charismatic personalities of a guslar such as Perovi?, secure the continuation of the tradition into the future.

Laji?-Mihajlovi? Danka

2007-01-01

394

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

395

[Introduction of traditional medicinal plants in Kyrgyzstan].  

Science.gov (United States)

Kyrgyzstan is a mountainous country in the northeastern part of Central Asia which shares borders to the southeast with China. Due to their extreme environment and climate, there are a diverse range of species of plants. Many of the plants used in Kyrgyz folk medicine have not been studied using modern scientific techniques. This paper introduced the basic situation of medicinal herbs in Kyrgyzstan by comparing the differences traditional use between China and Kyrgyzstan, and looked for traditional medicinal plant research to provide basis for the development and cooperation of China and Kyrgyzstan. PMID:24946536

Wang, Guo-Qiang; Huang, Lu-Qi; Xie, Dong-Mei

2014-02-01

396

Religious Tradition and the Archaic Man  

Directory of Open Access Journals (Sweden)

Full Text Available My article as a first step in a comprehensive research program attempts to verify the hypothesis according to which M. Eliade's morphological and historical investigations of archaic religiousness reveal the outlines of an archaic ontology. For this purpose, the article focuses upon Eliade's conception of religious tradition as the carrier of the indivisible unity of sacred existence and religious experience. The ontological difference found in religious existence and revealed by religious experience is rooted in the essentially hermeneutic nature of religious tradition. Therefore the perspective of philosophical hermeneutics proves very productive in the investigation of this problem.

Veress Károly

2005-04-01

397

Confucianism and the Asian Martial Traditions  

Directory of Open Access Journals (Sweden)

Full Text Available Confucianism has been foundational in the political and social life of many Asian countries. Its influence pervades institutions and practices at every level of human activity. Martial arts have also benefited from this philosophy, as the traditional Confucian legacy continues to influence modern practices. This article briefly highlights some key figures and events, describes relevant core concepts of Confucian philosophy, and then shows exemplary applications to martial arts today. Modern martial artists can gain understanding of the traditional Confucian insights that deepen the significance of contemporary martial arts.

C. Alexander Simpkins

2012-07-01

398

Social portrait of traditional medicine consumer  

Directory of Open Access Journals (Sweden)

Full Text Available The purpose of research is formation of a social portrait of the consumer of service of traditional medicine. Materials and methods. For research materials of sociological method — the questioning of patients lead in the state and private medical organizations of city of Saratov has been used. Processing of questionnaires has been lead by a method of mathematical statistics. Results. A social portrait of the consumer of services of traditional medicine and the principles influencing a choice of medical establishment are certain. Conclusion. Primary factor of patient's choice of private medical organizations is psychological readiness to pay for better medical aid

Muzalevskaya ?.V.

2012-03-01

399

Factors Influencing HEPA Filter Performance  

International Nuclear Information System (INIS)

Properly functioning HEPA air filtration systems depend on a variety of factors that start with the use of fully characterized challenge conditions for system design and then process control during operation. This paper addresses factors that should be considered during the design phase as well as operating parameters that can be monitored to ensure filter function and lifetime. HEPA filters used in nuclear applications are expected to meet design, fabrication, and performance requirements set forth in the ASME AG-1 standard. The DOE publication Nuclear Air Cleaning Handbook (NACH) is an additional guidance document for design and operation HEPA filter systems in DOE facilities. These two guidelines establish basic maximum operating parameters for temperature, maximum aerosol particle size, maximum particulate matter mass concentration, acceptable differential pressure range, and filter media velocity. Each of these parameters is discussed along with data linking variability of each parameter with filter function and lifetime. Temporal uncertainty associated with gas composition, temperature, and absolute pressure of the air flow can have a direct impact on the volumetric flow rate of the system with a corresponding impact on filter media velocity. Correlations between standard units of flow rate (standard meters per minute or cubic feet per minute) versus actual units of volumetric flow rate are shown for variations in relative humidity for a 70 deg. C to 200 deg. C ve humidity for a 70 deg. C to 200 deg. C temperature range as an example of gas composition that, uncorrected, will influence media velocity. The AG-1 standard establishes a 2.5 cm/s (5 feet per minute) ceiling for media velocities of nuclear grade HEPA filters. Data are presented that show the impact of media velocities from 2.0 to 4.0 cm/s media velocities (4 to 8 fpm) on differential pressure, filter efficiency, and filter lifetime. Data will also be presented correlating media velocity effects with two different particle size distributions. (authors)

400

Data-mining of potential antitubercular activities from molecular ingredients of traditional Chinese medicines  

Science.gov (United States)

Background. Traditional Chinese medicine encompasses a well established alternate system of medicine based on a broad range of herbal formulations and is practiced extensively in the region for the treatment of a wide variety of diseases. In recent years, several reports describe in depth studies of the molecular ingredients of traditional Chinese medicines on the biological activities including anti-bacterial activities. The availability of a well-curated dataset of molecular ingredients of traditional Chinese medicines and accurate in-silico cheminformatics models for data mining for antitubercular agents and computational filters to prioritize molecules has prompted us to search for potential hits from these datasets. Results. We used a consensus approach to predict molecules with potential antitubercular activities from a large dataset of molecular ingredients of traditional Chinese medicines available in the public domain. We further prioritized 160 molecules based on five computational filters (SMARTSfilter) so as to avoid potentially undesirable molecules. We further examined the molecules for permeability across Mycobacterial cell wall and for potential activities against non-replicating and drug tolerant Mycobacteria. Additional in-depth literature surveys for the reported antitubercular activities of the molecular ingredients and their sources were considered for drawing support to prioritization. Conclusions. Our analysis suggests that datasets of molecular ingredients of traditional Chinese medicines offer a new opportunity to mine for potential biological activities. In this report, we suggest a proof-of-concept methodology to prioritize molecules for further experimental assays using a variety of computational tools. We also additionally suggest that a subset of prioritized molecules could be used for evaluation for tuberculosis due to their additional effect against non-replicating tuberculosis as well as the additional hepato-protection offered by the source of these ingredients. PMID:25081126

Jamal, Salma

2014-01-01

401

Data-mining of potential antitubercular activities from molecular ingredients of traditional Chinese medicines  

Directory of Open Access Journals (Sweden)

Full Text Available Background. Traditional Chinese medicine encompasses a well established alternate system of medicine based on a broad range of herbal formulations and is practiced extensively in the region for the treatment of a wide variety of diseases. In recent years, several reports describe in depth studies of the molecular ingredients of traditional Chinese medicines on the biological activities including anti-bacterial activities. The availability of a well-curated dataset of molecular ingredients of traditional Chinese medicines and accurate in-silico cheminformatics models for data mining for antitubercular agents and computational filters to prioritize molecules has prompted us to search for potential hits from these datasets. Results. We used a consensus approach to predict molecules with potential antitubercular activities from a large dataset of molecular ingredients of traditional Chinese medicines available in the public domain. We further prioritized 160 molecules based on five computational filters (SMARTSfilter so as to avoid potentially undesirable molecules. We further examined the molecules for permeability across Mycobacterial cell wall and for potential activities against non-replicating and drug tolerant Mycobacteria. Additional in-depth literature surveys for the reported antitubercular activities of the molecular ingredients and their sources were considered for drawing support to prioritization. Conclusions. Our analysis suggests that datasets of molecular ingredients of traditional Chinese medicines offer a new opportunity to mine for potential biological activities. In this report, we suggest a proof-of-concept methodology to prioritize molecules for further experimental assays using a variety of computational tools. We also additionally suggest that a subset of prioritized molecules could be used for evaluation for tuberculosis due to their additional effect against non-replicating tuberculosis as well as the additional hepato-protection offered by the source of these ingredients.

Salma Jamal

2014-07-01

402

Current Loop High Performance Compensation Control Strategy Analysis of Active Power Filter  

Science.gov (United States)

By particular theoretical analyzing on detection error of the traditional current loop proportion-integral (PI) controller, this paper points out the limitations of detection harmonic current at load side and proposes a current feedforward compensation controller. It can track harmonic instructions with zero static error and good compensation performance. Meanwhile, it overcomes the deficiencies of traditional load side detection harmonic current PI controller, with the traditional controller's flexibility. Even if the load harmonic current is higher than the capacity of active power filter, it can basically maintain zero static error output and has certain theoretical significance and engineering value. Theoretical analysis and simulation prove the new control strategy's correctness and effectiveness.

Yuan, Qianqian

403

Broadband astigmatism-corrected spectrometer design using a toroidal lens and a special filter  

Science.gov (United States)

In the paper, a method to obtain a broadband, astigmatism-corrected spectrometer based on the existing Czerny-Turner spectrometer is proposed. The theories of astigmatism correction using a toroidal lens and a special filter are described in detail. Performance comparisons of the modified spectrometer and the traditional spectrometer are also presented. Results show that with the new design the RMS spot radius in sagittal view is one-eightieth of that in the traditional spectrometer over a broadband spectral range from 300 to 700 nm, without changing or moving any optical elements in the traditional spectrometer.

Ge, Xianying; Chen, Siying; Zhang, Yinchao; Chen, He; Guo, Pan; Mu, Taotao; Yang, Jian; Bu, Zhichao

2015-01-01

404

On-line filtering  

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.)

405

Filter-binding assays.  

Science.gov (United States)

Structural studies of DNA-protein complexes reveal networks of contacts between proteins and the phosphates, sugars and bases of DNA. Our understanding of these structures, especially at the usual level of resolution for complexes between proteins and DNA (1.5-3.0 A), is not sufficient to be able to infer directly the relative contributions of each contact to the overall binding energy. A range of biochemical methods have therefore been developed in order to probe the relative affinities of proteins for particular DNA target sites in vitro. Of these, one of the easiest and most widely used is nitrocellulose filter-binding. By exploiting the differential adsorption to nitrocellulose of proteins and peptides compared to nucleic acids, it is possible to prepare equilibrium mixtures of the proteins and nucleic acids of choice and estimate the amount of complex formation by rapid filtration. The concentration dependence of binding yields estimates of the equilibrium dissociation constant and trivial variations allow access to kinetic and thermodynamic data. The use of this technique is illustrated here using results from our experiments with the Escherichia coli methionine repressor, MetJ. PMID:19378155

Stockley, Peter G

2009-01-01

406

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

2013-04-01

407

Tunable HTS Filters  

Science.gov (United States)

The tunable HTS program goals are to develop a process, method, or device to tune high-temperature superconductor (HTS) resonant circuits. The process for tuning should preserve the low-loss nature of the s preconducting resonant circuits and be compatible with the operating environment of packaged HTS RF circuitry. Although we were originally developing three technologies to perform this tuning, we have down selected to the two that offer the greatest potential for high 0 operation, the half-HTS MEMS variable capacitor and the continuously variable inductor. The target application is for this technology is SIGINT applications in the 400 MHz to 3000 MHz frequency band, with potential applications in areas from 20 MHz to 20 GHz. We reached a significant milestone with the demonstration of the continuously variable inductors. In this demonstration we achieved a 23% tuning range, with better than 1 pan in 10,000 resettability, and a 0 of over 1.0,000. These are significant achievements in the area of tunable filters.

Mancusi, Joseph E.; Roberson, Mark

2002-06-01

408

Properties of ceramic candle filters  

Energy Technology Data Exchange (ETDEWEB)

The mechanical integrity of ceramic filter elements is a key issue for hot gas cleanup systems. To meet the demands of the advanced power systems, the filter components must sustain the thermal stresses of normal operations (pulse cleaning), of start-up and shut-down conditions, and of unanticipated process upsets such as excessive ash accumulation without catastrophic failure. They must also survive the various mechanical loads associated with handling and assembly, normal operation, and process upsets. For near-term filter systems, these elements must survive at operating temperatures of 1650{degrees}F for three years.

Pontius, D.H.

1995-06-01

409

Face Recognition using Gabor Filters  

Directory of Open Access Journals (Sweden)

Full Text Available An Elastic Bunch Graph Map (EBGM algorithm is being proposed in this research paper that successfully implements face recognition using Gabor filters. The proposed system applies 40 different Gabor filters on an image. As aresult of which 40 images with different angles and orientation are received. Next, maximum intensity points in each filtered image are calculated and mark them as Fiducial points. The system reduces these points in accordance to distance between them. The next step is calculating the distances between the reduced points using distance formula. At last, the distances are compared with database. If match occurs, it means that the image is recognized.

Sajjad MOHSIN

2011-01-01

410

Simplified design of filter circuits  

CERN Document Server

Simplified Design of Filter Circuits, the eighth book in this popular series, is a step-by-step guide to designing filters using off-the-shelf ICs. The book starts with the basic operating principles of filters and common applications, then moves on to describe how to design circuits by using and modifying chips available on the market today. Lenk's emphasis is on practical, simplified approaches to solving design problems.Contains practical designs using off-the-shelf ICsStraightforward, no-nonsense approachHighly illustrated with manufacturer's data sheets

Lenk, John

1999-01-01

411

Tunable Imaging Filters in Astronomy  

CERN Document Server

While tunable filters are a recent development in night time astronomy, they have long been used in other physical sciences, e.g. solar physics, remote sensing and underwater communications. With their ability to tune precisely to a given wavelength using a bandpass optimized for the experiment, tunable filters are already producing some of the deepest narrowband images to date of astrophysical sources. Furthermore, some classes of tunable filters can be used in fast telescope beams and therefore allow for narrowband imaging over angular fields of more than a degree over the sky.

Bland-Hawthorn, J

2000-01-01

412

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

2013-06-01

413

Ensemble Kalman filtering without the intrinsic need for inflation  

Directory of Open Access Journals (Sweden)

Full Text Available The main intrinsic source of error in the ensemble Kalman filter (EnKF is sampling error. External sources of error, such as model error or deviations from Gaussianity, depend on the dynamical properties of the model. Sampling errors can lead to instability of the filter which, as a consequence, often requires inflation and localization. The goal of this article is to derive an ensemble Kalman filter which is less sensitive to sampling errors. A prior probability density function conditional on the forecast ensemble is derived using Bayesian principles. Even though this prior is built upon the assumption that the ensemble is Gaussian-distributed, it is different from the Gaussian probability density function defined by the empirical mean and the empirical error covariance matrix of the ensemble, which is implicitly used in traditional EnKFs. This new prior generates a new class of ensemble Kalman filters, called finite-size ensemble Kalman filter (EnKF-N. One deterministic variant, the finite-size ensemble transform Kalman filter (ETKF-N, is derived. It is tested on the Lorenz '63 and Lorenz '95 models. In this context, ETKF-N is shown to be stable without inflation for ensemble size greater than the model unstable subspace dimension, at the same numerical cost as the ensemble transform Kalman filter (ETKF. One variant of ETKF-N seems to systematically outperform the ETKF with optimally tuned inflation. However it is shown that ETKF-N does not account for all sampling errors, and necessitates localization like any EnKF, whenever the ensemble size is too small. In order to explore the need for inflation in this small ensemble size regime, a local version of the new class of filters is defined (LETKF-N and tested on the Lorenz '95 toy model. Whatever the size of the ensemble, the filter is stable. Its performance without inflation is slightly inferior to that of LETKF with optimally tuned inflation for small interval between updates, and superior to LETKF with optimally tuned inflation for large time interval between updates.

M. Bocquet

2011-10-01

414

Ensemble Kalman filtering without the intrinsic need for inflation  

Science.gov (United States)

The main intrinsic source of error in the ensemble Kalman filter (EnKF) is sampling error. External sources of error, such as model error or deviations from Gaussianity, depend on the dynamical properties of the model. Sampling errors can lead to instability of the filter which, as a consequence, often requires inflation and localization. The goal of this article is to derive an ensemble Kalman filter which is less sensitive to sampling errors. A prior probability density function conditional on the forecast ensemble is derived using Bayesian principles. Even though this prior is built upon the assumption that the ensemble is Gaussian-distributed, it is different from the Gaussian probability density function defined by the empirical mean and the empirical error covariance matrix of the ensemble, which is implicitly used in traditional EnKFs. This new prior generates a new class of ensemble Kalman filters, called finite-size ensemble Kalman filter (EnKF-N). One deterministic variant, the finite-size ensemble transform Kalman filter (ETKF-N), is derived. It is tested on the Lorenz '63 and Lorenz '95 models. In this context, ETKF-N is shown to be stable without inflation for ensemble size greater than the model unstable subspace dimension, at the same numerical cost as the ensemble transform Kalman filter (ETKF). One variant of ETKF-N seems to systematically outperform the ETKF with optimally tuned inflation. However it is shown that ETKF-N does not account for all sampling errors, and necessitates localization like any EnKF, whenever the ensemble size is too small. In order to explore the need for inflation in this small ensemble size regime, a local version of the new class of filters is defined (LETKF-N) and tested on the Lorenz '95 toy model. Whatever the size of the ensemble, the filter is stable. Its performance without inflation is slightly inferior to that of LETKF with optimally tuned inflation for small interval between updates, and superior to LETKF with optimally tuned inflation for large time interval between updates.

Bocquet, M.

2011-10-01

415

Stability of Sunscreens Containing CePO4: Proposal for a New Inorganic UV Filter  

Directory of Open Access Journals (Sweden)

Full Text Available Inorganic UV filters have become attractive because of their role in protecting the skin from the damage caused by continuous exposure to the sun. However, their large refractive index and high photocatalytic activity have led to the development of alternative inorganic materials such as CePO4 for application as UV filters. This compound leaves a low amount of white residue on the skin and is highly stable. The aim of this study was to evaluate the physical and chemical stability of a cosmetic formulation containing ordinary organic UV filters combined with 5% CePO4, and, to compare it with other formulations containing the same vehicle with 5% TiO2 or ZnO as inorganic materials. The rheological behavior and chemical stability of the formulations containing these different UV filters were investigated. Results showed that the formulation containing CePO4 is a promising innovative UV filter due to its low interaction with organic filters, which culminates in longer shelf life when compared with traditional formulations containing ZnO or TiO2 filters. Moreover, the recognized ability of CePO4 to leave a low amount of white residue on the skin combined with great stability, suggests that CePO4 can be used as inorganic filter in high concentrations, affording formulations with high SPF values.

Vitor C. Seixas

2014-07-01

416

Particle Filter Improved by Genetic Algorithm and Particle Swarm Optimization Algorithm  

Directory of Open Access Journals (Sweden)

Full Text Available Particle filter algorithm is a filtering method which uses Monte Carlo idea within the framework of Bayesian estimation theory. It approximates the probability distribution by using particles and discrete random measure which is consisted of their weights, it updates new discrete random measure recursively according to the algorithm. When the sample is large enough, the discrete random measure approximates the true posteriori probability density function of the state variable. The particle filter algorithm is applicable to any non-linear non-Gaussian system. But the standard particle filter does not consider the current measured value, which will lead to particles with non-zero weights become less after some iterations, this results in particle degradation; re-sampling technique was used to inhibit degradation, but this will reduce the particle diversity, and results in particle impoverishment. To overcome the problems, this paper proposed a new particle filter which introduced genetic algorithm and particle swarm optimization algorithm. The new algorithm is called intelligent particle filter (IPF. Driving particles move to the optimal position by using particle swarm optimization algorithm, thus the numbers of effective particles was increased, the particle diversity was improved, and the particle degradation was inhibited. Replace the re-sampling method in traditional particle filter by using the choice, crossover and mutation operation of the genetic algorithm, avoiding the phenomenon of impoverishment. Simulation results show that the new algorithm improved the estimation accuracy significantly compare with the standard particle filter.

Ming Li

2013-03-01

417

Perceptions of a Chilly Climate: Differences in Traditional and Non-Traditional Majors for Women  

Science.gov (United States)

The purpose of this study was to examine how perceptions of a chilly climate differ between students in traditionally female-dominated majors (nursing and education) versus traditionally male-dominated majors (information technology and engineering), and how these perceptions relate to students' intentions to persist or pursue higher education in…

Morris, LaDonna K.; Daniel, Larry G.

2008-01-01

418

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

2012-01-01

419

Fuel Efficient Diesel Particulate Filter (DPF) Modeling and Development  

Energy Technology Data Exchange (ETDEWEB)

The project described in this report seeks to promote effective diesel particulate filter technology with minimum fuel penalty by enhancing fundamental understanding of filtration mechanisms through targeted experiments and computer simulations. The overall backpressure of a filtration system depends upon complex interactions of particulate matter and ash with the microscopic pores in filter media. Better characterization of these phenomena is essential for exhaust system optimization. The acicular mullite (ACM) diesel particulate filter substrate is under continuing development by Dow Automotive. ACM is made up of long mullite crystals which intersect to form filter wall framework and protrude from the wall surface into the DPF channels. ACM filters have been demonstrated to effectively remove diesel exhaust particles while maintaining relatively low backpressure. Modeling approaches developed for more conventional ceramic filter materials, such as silicon carbide and cordierite, have been difficult to apply to ACM because of properties arising from its unique microstructure. Penetration of soot into the high-porosity region of projecting crystal structures leads to a somewhat extended depth filtration mode, but with less dramatic increases in pressure drop than are normally observed during depth filtration in cordierite or silicon carbide filters. Another consequence is greater contact between the soot and solid surfaces, which may enhance the action of some catalyst coatings in filter regeneration. The projecting crystals appear to provide a two-fold benefit for maintaining low backpressures during filter loading: they help prevent soot from being forced into the throats of pores in the lower porosity region of the filter wall, and they also tend to support the forming filter cake, resulting in lower average cake density and higher permeability. Other simulations suggest that soot deposits may also tend to form at the tips of projecting crystals due to the axial velocity component of exhaust moving down the filter inlet channel. Soot mass collected in this way would have a smaller impact on backpressure than soot forced into the flow restrictions deeper in the porous wall structure. This project has focused on the development of computational, analytical, and experimental techniques that are generally applicable to a wide variety of exhaust aftertreatment technologies. By helping to develop improved fundamental understanding pore-scale phenomena affecting filtration, soot oxidation, and NOX abatement, this cooperative research and development agreement (CRADA) has also assisted Dow Automotive in continuing development and commercialization of the ACM filter substrate. Over the course of this research project, ACM filters were successfully deployed on the Audi R10 TDI racecar which won the 24 Hours of LeMans endurance race in 2006, 2007, and 2008; and the 12 Hours of Sebring endurance race in 2006 and 2007. It would not have been possible for the R10 to compete in these traditionally gasoline-dominated events without reliable and effective exhaust particulate filtration. These successes demonstrated not only the performance of automotive diesel engines, but the efficacy of DPF technology as it was being deployed around the world to meet new emissions standards on consumer vehicles. During the course of this CRADA project, Dow Automotive commercialized their ACM DPF technology under the AERIFYTM DPF brand.

Stewart, Mark L.; Gallant, Thomas R.; Kim, Do Heui; Maupin, Gary D.; Zelenyuk, Alla

2010-08-01

420

Utilizing Traditional Knowledge in a Scientific Setting.  

Science.gov (United States)

A nuclear physicist feels that his Navajo upbringing, with its emphasis on the structure of nature and abstract reasoning, prepared him well for the world of physics. Traditional Navajo sandpaintings helped him understand physics concepts. Native American students show strengths in learning visual, perceptual, or spatial information, and they…

Boyne, Grace M.

2003-01-01

421

Loss and mourning in the jewish tradition.  

Science.gov (United States)

Robert Kastenbaum was a man who helped reintroduce issues related to death, dying, and bereavement to academic, clinical, and general discourse. This article, devoted to an encounter with the observance of mourning custom and ritual in the Jewish tradition, continues the dialogue in this journal that Bob founded. The article utilizes the Two-Track Model of Bereavement to address the Jewish tradition's structuring of the loss experience. After a brief introduction, I present a schematic presentation of some of the issues operant in grief and mourning for the believer. This is followed by two responses to loss that portray the pain of loss in the tradition. The article goes on to consider the Jewish time cycle of response to loss-from preburial Aninut, to Shiva, the first week, to Shloshim, the first month, to Shanah, the first year, to the expectations for encounters across the life cycle. The Yizkor and Kaddish are also considered. In the Jewish tradition, alongside attention to what level of functioning to require of the bereaved, there are lifelong opportunities to rework and maintain connection to the memories, associations, narratives, and experiences that comprise the psychological organization of the continuing bond and relationship to the deceased. PMID:25351592

Rubin, Simon Shimshon

2014-01-01

422

Alternative Approaches to Traditional Topics in Algebra  

Science.gov (United States)

Students who otherwise seem unreachable through traditional approaches to algebra require some alternative teaching methods. So do teachers who seek to add elements of freshness and innovation to their classrooms or who simply appreciate variety. This article offers some unconventional techniques for teaching a few conventional algebra topics.…

Coburn, John W.

2010-01-01

423

The Watergate Seminar: Non-Traditional College  

Science.gov (United States)

Empire State College, a non-traditional unit of the State University of New York, conducted a series of seminars related to the Watergate Affair, at which 23 students took part in this intensive exploration of a Watergate. It provided tremendous opportunity for insight into the concept of seminars within a college. (Author)

Harrison, Joseph

1977-01-01

424

Enhancing the Lecture: Revitalizing the Traditional Format.  

Science.gov (United States)

The traditional lecture format of college courses can be enhanced by including active learning designed to further course goals of learning knowledge, developing skills, or fostering attitudes. Techniques suggested include using pauses, short writing periods, think-pair-share activities, formative quizzes, lecture summaries, and several assessment…

Bonwell, Charles C.

1996-01-01

425

Confucianism and the Asian Martial Traditions  

OpenAIRE

Confucianism has been foundational in the political and social life of many Asian countries. Its influence pervades institutions and practices at every level of human activity. Martial arts have also benefited from this philosophy, as the traditional Confucian legacy continues to influence modern practic...

Alexander Simpkins, C.; Simpkins, Annellen M.

2012-01-01

426

Interview with a Traditional African Healer.  

Science.gov (United States)

A counselor educator interviews a well-known traditional African healer in a village in Burkina Faso, West Africa, to learn how he chose his profession, the content and duration of his preparation, how he relates to his clients, and how he diagnoses their problems and intervenes on their behalf. (Author/GCP)

Vontress, Clemmont E.

1999-01-01

427

Spotlight on Ramayana: An Enduring Tradition.  

Science.gov (United States)

This collection of lessons was developed by teachers in an institute focusing on teaching about India and the Ramayana. Essays providing background information are "The Oral Tradition and the Many 'Ramayanas'" (Philip Lutgendorf) and "Bringing Ramayana into the Classroom" (Hazel Sara Greenberg). After an introduction by Susan Wadley, a Ramayana…

Wadley, Susan, Ed.; Ramamurthy, Priti, Ed.

428

Canarian ethnoastronomy: the voyage of a tradition?  

Science.gov (United States)

A large and deep ethnoastronomical fieldwork has been performed in the Canary Islands of Tenerife, Fuerteventura, Lanzarote, Gomera and Gran Canaria during 1995 and 1996. Numerous and challenging astronomical traditions, almost at the border of extinction, have been found among aged shepherds and peasants of these island.

Barrios, M. Sanz De Lara; Belmonte, J. A.; Perera Betancort, A.; Méndez Corona, C.; Schlueter Caballero, R.

429

Institutional Traditions in Teachers' Manners of Teaching  

Science.gov (United States)

The aim of this article is to make a close case study of one teacher's teaching in relation to established traditions within science education in Sweden. The teacher's manner of teaching is analysed with the help of an epistemological move analysis. The moves made by the teacher are then compared in a context of educational philosophy and…

Lundqvist, Eva; Almqvist, Jonas; Ostman, Leif

2012-01-01

430

An Alternative to the Traditional Grading System.  

Science.gov (United States)

The purpose of this practicum was to change the grading policy in the San Juan Unified School District (California) through a two-state process. The first stage was to change the traditional ABCDF grading system to a three-scale grading system in one high school, one intermediate school, and six elementary schools serving the same attendance area.…

Galvez, Ferdinand V.

431

Primary care within the academic tradition.  

Science.gov (United States)

In the rush to train primary-care physicians, the bioscience tradition must remain inviolate. At the same time, however, academic medicine should recognize that the actual practice of medicine has a special content and operational philosophy that is indispensable for patient care and in which, therefore, every student should be versed. PMID:1173918

Burnum, J F

1975-09-01

432

Industrial redesign of traditional valencian tiles  

Directory of Open Access Journals (Sweden)

Full Text Available The idea behind this project was to recover a type of Traditional Valencian Ceramics, by adapting its own particular production technology to present-day systems, installations and materials.

Se ha pretendido recuperar una tipología de Cerámica tradicional Valenciana, adaptando su tecnología productiva a los sistemas , instalaciones y materiales actuales.

Lucas, F.

2000-02-01

433

Evaluation of French Guiana traditional antimalarial remedies.  

Science.gov (United States)

In order to evaluate the antimalarial potential of traditional remedies used in French Guiana, 35 remedies were prepared in their traditional form and screened for blood schizonticidal activity in vitro on Plasmodium falciparum chloroquine re4sistant strain (W2). Some of these extracts were screened in vivo against Plasmodium yoelii rodent malaria. Ferriprotoporphyrin inhibition test was also performed. Four remedies, widely used among the population as preventives, were able to inhibit more than 50% of the parasite growth in vivo at around 100 mg/kg: Irlbachia alata (Gentiananceae), Picrolemma pseudocoffea (Simaroubaceae), Quassia amara (Simaroubaceae), Tinospora crispa (Menispermaceae) and Zanthoxylum rhoifolium (Rutaceae). Five remedies displayed an IC50 in vitro < 10 microg/ml: Picrolemma pseudocoffea, Pseudoxandra cuspidata (Annonaceae) and Quassia amara leaves and stem, together with a multi-ingredient recipe. Two remedies were more active than a Cinchona preparation on the ferriprotoporphyrin inhibition test: Picrolemma pseudocoffea and Quassia amara. We also showed that a traditional preventive remedy, made from Geissospermum argenteum bark macerated in rum, was able to impair the intrahepatic cycle of the parasite. For the first time, traditional remedies from French Guiana have been directly tested on malarial pharmacological assays and some have been shown to be active. PMID:15849870

Bertani, S; Bourdy, G; Landau, I; Robinson, J C; Esterre, Ph; Deharo, E

2005-04-01

434

Insights: The Myth of the Traditional Family  

Science.gov (United States)

According to the U.S. Census Bureau, more than half of marriages have ended in divorce since the mid-1970s. Nonetheless, schools and community organizations continue to be inclined to act as if nontraditional/neo-traditional families are an anomaly. Despite the reality of new family structures, popular television, movies, and books continue to…

Willis, Mariam

2012-01-01

435

Filter multiplexing by use of spatial Code Division Multiple Access approach.  

Science.gov (United States)

The increasing popularity of optical communication has also brought a demand for a broader bandwidth. The trend, naturally, was to implement methods from traditional electronic communication. One of the most effective traditional methods is Code Division Multiple Access. In this research, we suggest the use of this approach for spatial coding applied to images. The approach is to multiplex several filters into one plane while keeping their mutual orthogonality. It is shown that if the filters are limited by their bandwidth, the output of all the filters can be sampled in the original image resolution and fully recovered through an all-optical setup. The theoretical analysis of such a setup is verified in an experimental demonstration. PMID:12593478

Solomon, Jonathan; Zalevsky, Zeev; Mendlovic, David; Monreal, Javier Garcia

2003-02-10

436

Experience with three percutaneous vena cava filters  

International Nuclear Information System (INIS)

Twenty-one Kimray-Greenfield, 33 bird's nest, and 19 Amplatz vena cava filters were placed percutaneously. The Kimray-Greenfield filter was the most difficult to insert. The major problem was the insertion site, which required venipuncture with a 24-F catheter. Minor hemorrhage was frequent, and femoral vein thrombosis occurred in four patients. No migration, caval thrombosis, or pulmonary emboli were seen after Kimray-Greenfield filter placement. The bird's nest filter was relatively easy to insert, although in two cases the filter prongs could not be adequately seated in the wall of the inferior vena cava. Three patients with bird's nest filters had thrombosis below the filter, and three filters migrated to the heart. One migrated filter could not be removed. One patient had multiple small pulmonary emboli at autopsy. No other pulmonary emboli after filter placement were noted. The Amplatz filter was the easiest of the three filters to insert. Only one patient with an Amplatz filter had thrombosis of the vena cava below the filter. No filter migrations were documented, and no recurrent pulmonary emboli were found on clinical or radiologic follow-up. The Amplatz vena cava filter is easier to place than percutaneous Kimray-Greenfield or bird's nest filters, has a low complication rate, and has proven to be clinically effective in preventing pulmonary emboli

437

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.

2009-01-01

438

Interference filters for Schmidt telescopes.  

Science.gov (United States)

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.

439

Filtering Dialysis Myths from Facts  

Science.gov (United States)

... Family NKF Store Featured Story Are you a dialysis patient? Sign up for our FREE magazine, Kidney ... Newsroom Contact Us You are here Home » Filtering Dialysis Myths from Facts Myth: The only option for ...

440

Wiener Chaos and Nonlinear Filtering  

International Nuclear Information System (INIS)

The paper discusses two algorithms for solving the Zakai equation in the time-homogeneous diffusion filtering model with possible correlation between the state process and the observation noise. Both algorithms rely on the Cameron-Martin version of the Wiener chaos expansion, so that the approximate filter is a finite linear combination of the chaos elements generated by the observation process. The coefficients in the expansion depend only on the deterministic dynamics of the state and observation processes. For real-time applications, computing the coefficients in advance improves the performance of the algorithms in comparison with most other existing methods of nonlinear filtering. The paper summarizes the main existing results about these Wiener chaos algorithms and resolves some open questions concerning the convergence of the algorithms in the noise-correlated setting. The presentation includes the necessary background on the Wiener chaos and optimal nonlinear filtering

441

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)

442

Image Recommendation Algorithm Using Feature-Based Collaborative Filtering  

Science.gov (United States)

As the multimedia contents market continues its rapid expansion, the amount of image contents used in mobile phone services, digital libraries, and catalog service is increasing remarkably. In spite of this rapid growth, users experience high levels of frustration when searching for the desired image. Even though