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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  

Energy Technology Data Exchange (ETDEWEB)

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.)

Moscariello, Antonio [Medical University of South Carolina, Heart and Vascular Center, Charleston, SC (United States); Catholic University of the Sacred Heart, ' ' A. Gemelli' ' Hospital, Department of Bioimaging and Radiological Sciences, Rome (Italy); Takx, Richard A.P. [Medical University of South Carolina, Heart and Vascular Center, Charleston, SC (United States); Maastricht University Medical Center, Department of Radiology, Maastricht (Netherlands); Schoepf, U.J.; Renker, Matthias; Zwerner, Peter L. [Medical University of South Carolina, Heart and Vascular Center, Charleston, SC (United States); O' Brien, Terrence X. [Medical University of South Carolina, Heart and Vascular Center, Charleston, SC (United States); The Ralph H. Johnson Veterans Affairs Medical Center, Charleston, SC (United States); Allmendinger, Thomas; Schmidt, Bernhard [Siemens AG, Healthcare Sector, Forchheim (Germany); Vogt, Sebastian [Siemens Medical Solutions USA, Malvern, PA (United States); Savino, Giancarlo; Bonomo, Lorenzo [Catholic University of the Sacred Heart, ' ' A. Gemelli' ' Hospital, Department of Bioimaging and Radiological Sciences, Rome (Italy); Fink, Christian; Henzler, Thomas [Medical University of South Carolina, Heart and Vascular Center, Charleston, SC (United States); Heidelberg University, Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg (Germany)

2011-10-15

2

Filter back-projection technique applied to Abel inversion  

International Nuclear Information System (INIS)

The inverse Abel transform is applicable to optically thin plasma with cylindrical symmetry, which is often encountered in plasma physics and inertial (or magnetic) confinement fusion. The filter back-projection technique is modified, and then a new method of inverse Abel transform is presented

3

Filtered back projection inversion of turntable ISAR data  

Science.gov (United States)

In this paper, an inversion scheme for near-field inverse synthetic aperture radar (ISAR) data is derived for both two and three dimensions from a scalar wave equation model. The proposed data inversion scheme motivates the use of a filtered back projection (FBP) imaging algorithm. The paper provides a derivation of the the general imaging filter needed for FBP, which will be shown to reduce to a familiar result for near-field ISAR imaging.

Lopez, Jaime X.; Qiao, Zhijun

2011-06-01

4

The Gradient and laplacien filtered back projection operators  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents a new method, based on the Filtered Back Projection technique (FBP) to compute directly the values of the gradient and the laplacien of an X-Ray image. We propose a way to pre-process the raw data that allow us to compute directly the reconstructed values of the gradient or of the laplacien at any location in the plane (defined with real coordinates) without reconstructing an image of the absorption coefficients. The reconstructed values of the gradient and of the laplacie...

Thirion, Jean-philippe

1992-01-01

5

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

6

Research of inverse synthetic aperture imaging lidar based on filtered back-projection tomography technique  

Science.gov (United States)

In order to obtain clear two-dimensional image under the conditions without using heterodyne interferometry by inverse synthetic aperture lidar(ISAL), designed imaging algorithms based on filtered back projection tomography technique, and the target "A" was reconstructed with simulation algorithm by the system in the turntable model. Analyzed the working process of ISAL, and the function of the reconstructed image was given. Detail analysis of the physical meaning of the various parameters in the process of echo data, and its parameters affect the reconstructed image. The image in test area was reconstructed by the one-dimensional distance information with filtered back projection tomography technique. When the measured target rotated, the sum of the echo light intensity at the same distance was constituted by the different position of the measured target. When the total amount collected is large enough, multiple equations can be solved change. Filtered back-projection image of the ideal image is obtained through MATLAB simulation, and analyzed that the angle intervals affected the reconstruction of image. The ratio of the intensity of echo light and loss light affected the reconstruction of image was analyzed. Simulation results show that, when the sampling angle is smaller, the resolution of the reconstructed image of measured target is higher. And the ratio of the intensity of echo light and loss light is greater, the resolution of the reconstructed image of measured target is higher. In conclusion after some data processing, the reconstructed image basically meets be effective identification requirements.

Liu, Zhi-chao; Yang, Jin-hua

2014-07-01

7

Data correction in reconstructing the image of CBS in the manner of filtered back-projection  

International Nuclear Information System (INIS)

CBS is a non-destruction detection technology, which was recently developed. The different in contrast with the conventional CT is that the conventional CT uses the integration of the X-ray absorptivity of the various apparatus to reconstruct the image, and that the CBS uses the rate at which the incidence ray are scattered from a particular region to reconstruct the image. The paper primarily analyses the data correction in reconstructing the image of CBS in the manner of classical filtered back-projection. (authors)

8

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

9

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)

10

Comparison of parabolic filtration methods for 3D filtered back projection in pulsed EPR imaging  

Science.gov (United States)

Pulse electron paramagnetic resonance imaging (Pulse EPRI) is a robust method for noninvasively measuring local oxygen concentrations in vivo. For 3D tomographic EPRI, the most commonly used reconstruction algorithm is filtered back projection (FBP), in which the parabolic filtration process strongly influences image quality. In this work, we designed and compared 7 parabolic filtration methods to reconstruct both simulated and real phantoms. To evaluate these methods, we designed 3 error criteria and 1 spatial resolution criterion. It was determined that the 2 point derivative filtration method and the two-ramp-filter method have unavoidable negative effects resulting in diminished spatial resolution and increased artifacts respectively. For the noiseless phantom the rectangular-window parabolic filtration method and sinc-window parabolic filtration method were found to be optimal, providing high spatial resolution and small errors. In the presence of noise, the 3 point derivative method and Hamming-window parabolic filtration method resulted in the best compromise between low image noise and high spatial resolution. The 3 point derivative method is faster than Hamming-window parabolic filtration method, so we conclude that the 3 point derivative method is optimal for 3D FBP.

Qiao, Zhiwei; Redler, Gage; Epel, Boris; Halpern, Howard J.

2014-11-01

11

Imaging in turbid media by modified filtered back projection method using data from Monte Carlo simulation  

Science.gov (United States)

Noninvasive diagnosis in medicine has shown considerable attention in recent years. Several methods are already available for imaging the biological tissue like X-ray computerized tomography, magentic resonance imaging and ultrasound imaging et c. But each of these methods has its own disadvantages. Optical tomography which uses NIR light is one of the emerging methods in teh field of medical imaging because it is non-invasive in nature. The only problem that occurs in using light for imaging the tissue is that it is highly scattered inside tissue, so the propagation of light in tissue is not confined to straight lines as is the case with X-ray tomography. Therefore the need arises to understand the behaviour of propagation of light in tissue. There are several methods for light interaction with tissue. Monte Carlo method is one of these methods which is a simple technique for simulation of light through tissue. The only problem faced with Monte Carlo simulation is its high computational time. Once the data is obtained using Monte Carlo simulation, it need to be inverted to obtain the reconstruction of tissue image. There are standard methods of reconstruction like algebraic reconstruction method, filtered backprojection method etc. But these methods can not be used as such in the case when light is used as probing radiations because it is highly scattered inside the tissue. The standard filtered backprojection method has been modified so that the zigzag path of photons is taken into consideration while back projecting the data. This is achieved by dividing the tissue domain in a square grid and storing the average path traversed in each grid element. It has been observed that the reconstruction obtained using this modification is much better than the result in case of standard filtered backprojection method.

Aggarwal, Ashwani; Vasu, Ram M.

2003-07-01

12

The Comparison of Iterative and Filtered Back Projection Method for Gamma-ray CT  

International Nuclear Information System (INIS)

There are two categories for an image reconstruction, the transform based reconstruction and the iterative reconstruction technique. The transform based reconstruction is based on an inverse radon transform theory. Filtered Back Projection (FBP) method is a frequently used algorithm based on radon model. In FBP, it is assumed that the measured data consist of line integrals of the object distribution. Iterative reconstruction technique is the method in which the estimated image is progressively refined in a repetitive calculation. For X-ray CT, FBP has been the most powerful technique because it has the sufficient number of total ray-sums. Unlike the X-ray CT, there are situations where it is not possible to measure a large number of projections for the industrial gamma-ray CT. In addition to aforementioned factors, there are many different characteristics between the gamma-ray and Xray. To get a precise image from gamma-ray CT, the adequate image reconstruction algorithm should be adopted. To evaluate the algorithm suitable for gamma ray CT, comparison of iterative and FBP method result from the gamma-ray CT is introduced

13

2D and 3D ISAR image reconstruction through filtered back projection  

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This paper presents a 3D ltered inversion scheme for turntable inverse synthetic aperture radar (ISAR) data from a scalar wave equation model. The proposed inversion scheme targets at the use of ltered back projection (FBP) and convolution back projection (CBP) imaging algorithms. In the paper, we also provide a derivation of a general imaging lter for the near-elds FBP and CBP imaging algorithms.

Ray, Timothy; Cao, Yufeng; Qiao, Zhijun; Chen, Genshe

2012-06-01

14

Submillisievert Chest CT With Filtered Back Projection and Iterative Reconstruction Techniques.  

Science.gov (United States)

OBJECTIVE. The purpose of this study was to compare submillisievert chest CT images reconstructed with filtered back projection (FBP), SafeCT, adaptive statistical iterative reconstruction (ASIR), and model-based iterative reconstruction (MBIR) with standard of care FBP images. SUBJECTS AND METHODS. Fifty patients (33 men and 17 women; mean age [± SD], 62 ± 10 years) undergoing routine chest CT gave written informed consent for acquisition of an additional submillisievert chest CT series with reduced tube current but identical scanning length as standard of care chest CT. Sinogram data of the submillisievert series were reconstructed with FBP, SafeCT, ASIR, and MBIR and compared with FBP images at standard-dose chest CT (n = 8 × 50 = 400 series). Two thoracic radiologists performed independent comparison for visualization of lesion margin, visibility of small structures, and diagnostic acceptability. Objective noise measurements and noise spectral density were obtained. RESULTS. Of 287 detected lesions, 162 were less than 1-cm noncalcified nodules. Lesion margins were well seen on all submillisievert reconstruction images except MBIR, on which they were poorly visualized. Likewise, only submillisievert MBIR images were suboptimal for visibility of normal structures, such as pulmonary vessels in the outer 2 cm of the lung, interlobular fissures, and subsegmental bronchial walls. MBIR had the lowest image noise compared with other techniques. CONCLUSION. FBP, SafeCT, ASIR, and MBIR can enable optimal lesion evaluation on chest CT acquired at a volume CT dose index of 2 mGy. However, all submillisievert reconstruction techniques were suboptimal for visualization of mediastinal structures. Submillisievert MBIR images were suboptimal for visibility of normal lung structures despite showing lower image noise. PMID:25247943

Padole, Atul; Singh, Sarabjeet; Ackman, Jeanne B; Wu, Carol; Do, Synho; Pourjabbar, Sarvenaz; Khawaja, Ranish Deedar Ali; Otrakji, Alexi; Digumarthy, Subba; Shepard, Jo-Anne; Kalra, Mannudeep

2014-10-01

15

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

International Nuclear Information System (INIS)

Purpose: To compare image quality and visualization of normal structures and lesions in brain computed tomography (CT) with adaptive statistical iterative reconstruction (ASIR) and filtered back projection (FBP) reconstruction techniques in different X-ray tube current–time products. Materials and methods: In this IRB-approved prospective study, forty patients (nineteen men, twenty-one women; mean age 69.5 ± 11.2 years) received brain scan at different tube current–time products (300 and 200 mAs) in 64-section multi-detector CT (GE, Discovery CT750 HD). Images were reconstructed with FBP and four levels of ASIR-FBP blending. Two radiologists (please note that our hospital is renowned for its geriatric medicine department, and these two radiologists are more experienced in chronic cerebral vascular disease than in neoplastic disease, so this research did not contain cerebral tumors but as a discussion) assessed all the reconstructed images for visibility of normal structures, lesion conspicuity, image contrast and diagnostic confidence in a blinded and randomized manner. Volume CT dose index (CTDIvol) and dose-length product (DLP) were recorded. All the data were analyzed by using SPSS 13.0 statistical analysis software. Results: There was no statistically significant difference between the image qualities at 200 mAs with 50% ASIR blending technique and 300 mAs with FBP technique (p > .05). While between the image qualities at 200 mAs with FBP and 300 mAs with FBP technique a statistically significant difference (p < .05) was found. Conclusion: ASIR provided same image quality and diagnostic ability in brain imaging with greater than 30% dose reduction compared with FBP reconstruction technique

16

CT coronary angiography: Image quality with sinogram-affirmed iterative reconstruction compared with filtered back-projection  

International Nuclear Information System (INIS)

Aim: To investigate image quality and potential for radiation dose reduction using sinogram-affirmed iterative reconstruction (SAFIRE) at computed tomography (CT) coronary angiography (CTCA) compared with filtered back-projection (FBP) reconstruction. Materials and methods: A water phantom and 49 consecutive patients were scanned using a retrospectively electrocardiography (ECG)-gated CTCA protocol on a dual-source CT system. Image reconstructions were performed with both conventional FBP and SAFIRE. The SAFIRE series were reconstructed image data from only one tube, simulating a 50% radiation dose reduction. Two blinded observers independently assessed the image quality of each coronary segment using a four-point scale and measured image noise (the standard deviation of Hounsfield values, SD), signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). Radiation dose estimates were calculated. Results: In the water phantom, image noise decreased at the same ratio as the tube current increased for both reconstruction algorithms. Despite an estimated radiation dose reduction from 7.9 ± 2.8 to 4 ± 1.4 mSv, there was no significant difference in the SD and SNR within the aortic root and left ventricular chamber between the two reconstruction methods. There was also no significant difference in the image quality between the FBP and SAFIRE series. Conclusion: Compared with traditional FBP, there is potential for substantial radiation dose reduction at CTCA with use of SAFIRE, while maintaining similar diagnostic image quality

17

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

18

Imaging reconstruction based on improved wavelet denoising combined with parallel-beam filtered back-projection algorithm  

Science.gov (United States)

The image reconstruction is a key step in medical imaging (MI) and its algorithm's performance determinates the quality and resolution of reconstructed image. Although some algorithms have been used, filter back-projection (FBP) algorithm is still the classical and commonly-used algorithm in clinical MI. In FBP algorithm, filtering of original projection data is a key step in order to overcome artifact of the reconstructed image. Since simple using of classical filters, such as Shepp-Logan (SL), Ram-Lak (RL) filter have some drawbacks and limitations in practice, especially for the projection data polluted by non-stationary random noises. So, an improved wavelet denoising combined with parallel-beam FBP algorithm is used to enhance the quality of reconstructed image in this paper. In the experiments, the reconstructed effects were compared between the improved wavelet denoising and others (directly FBP, mean filter combined FBP and median filter combined FBP method). To determine the optimum reconstruction effect, different algorithms, and different wavelet bases combined with three filters were respectively test. Experimental results show the reconstruction effect of improved FBP algorithm is better than that of others. Comparing the results of different algorithms based on two evaluation standards i.e. mean-square error (MSE), peak-to-peak signal-noise ratio (PSNR), it was found that the reconstructed effects of the improved FBP based on db2 and Hanning filter at decomposition scale 2 was best, its MSE value was less and the PSNR value was higher than others. Therefore, this improved FBP algorithm has potential value in the medical imaging.

Ren, Zhong; Liu, Guodong; Huang, Zhen

2012-11-01

19

Motion-compensated and gated cone beam filtered back-projection for 3-D rotational X-ray angiography.  

Science.gov (United States)

This paper presents a method to reconstruct moving objects from cone beam X-ray projections acquired during a single rotational run using a given motion vector field. The method is applicable to voxel driven cone-beam filtered back-projection reconstruction approaches. Here, a formulation based on the algorithm of Feldkamp, Davis, and Kress (FDK) is presented. The motion correction is applied during the back-projection step by shifting the voxel to be reconstructed according to the motion vector field. The method is applied to three-dimensional (3-D) rotational X-ray angiography. Projections from a beating coronary heart phantom are simulated. Motion-compensated reconstructions with varying accuracy of the applied motion field are carried out for a late diastolic heart phase and compared to the reconstruction obtained with the standard FDK-method from projections of the corresponding motion-free model in the same heart phase. Furthermore, gated reconstructions are calculated by weighting the projections according to their cardiac phase without using a motion vector field. Different gating window widths are applied, and the reconstructions are compared. Using the correct motion field with the motion-compensated reconstruction, the image quality of the standard reconstruction from the corresponding motion-free coronary model can almost be recovered. The reconstructed image quality stays acceptable if the accuracy of the motion field sampling points is better than 1 mm. The gated reconstructions with a window width of 15%-20% of the cardiac cycle lead to superior results compared to nearest neighbor gating, especially for histogram based visualization and analysis. The motion-compensated reconstructions provide sharp images of the coronaries far surpassing the image quality of gated reconstructions. PMID:16827490

Schäfer, Dirk; Borgert, Jörn; Rasche, Volker; Grass, Michael

2006-07-01

20

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

 
 
 
 
21

Improved accuracy of pulmonary embolism computer-aided detection using iterative reconstruction compared with filtered back projection.  

Science.gov (United States)

OBJECTIVE. The purpose of this study was to determine whether use of iterative reconstruction (IR) can improve performance of a pulmonary embolism computer-aided detection (PE CAD) prototype. MATERIALS AND METHODS. Images were collected from 40 consecutive pulmonary CT angiographic examinations in which PE was found and 26 studies in which it was not found for use as control cases. All images were reconstructed with filtered back projection (FBP) and six levels of a hybrid IR algorithm. The studies were evaluated with a prototype PE CAD system, and its performance was comparatively assessed on the basis of reconstruction type on a per-embolus and a per-study basis. RESULTS. Use of the hybrid IR algorithm led to a significant and progressive decrease in false-positive marks made by PE CAD compared with those made by radiologists on FBP reconstructions (239 false-positive marks for FBP and 154, 136, 125, 116, 107, and 98 false-positive marks for the six hybrid IR [HIR] levels). Specificity improved with increasing HIR level (45.6% for level 6; 30.3% for FBP). However, compared with FBP, increasing levels of HIR resulted in a progressive decrease in per-embolism sensitivity (70.3% for FBP; 55.4% for HIR level 6) and, with the exception of HIR level 4, a progressive decrease in per-study sensitivity (97.5% for FBP; 85.0% for HIR level 6). Overall accuracy was highest for HIR level 1 (77.3%). CONCLUSION. The use of IR leads to a significant reduction in false-positive marks by PE CAD at a cost of decreasing sensitivity. Very high levels of IR, which had the lowest sensitivities, should be avoided if being used concomitantly with PE CAD. PMID:25247942

Lahiji, Kian; Kligerman, Seth; Jeudy, Jean; White, Charles

2014-10-01

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)

24

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

25

Quantitative analysis of emphysema and airway measurements according to iterative reconstruction algorithms: comparison of filtered back projection, adaptive statistical iterative reconstruction and model-based iterative reconstruction  

International Nuclear Information System (INIS)

To evaluate filtered back projection (FBP) and two iterative reconstruction (IR) algorithms and their effects on the quantitative analysis of lung parenchyma and airway measurements on computed tomography (CT) images. Low-dose chest CT obtained in 281 adult patients were reconstructed using three algorithms: FBP, adaptive statistical IR (ASIR) and model-based IR (MBIR). Measurements of each dataset were compared: total lung volume, emphysema index (EI), airway measurements of the lumen and wall area as well as average wall thickness. Accuracy of airway measurements of each algorithm was also evaluated using an airway phantom. EI using a threshold of -950 HU was significantly different among the three algorithms in decreasing order of FBP (2.30 %), ASIR (1.49 %) and MBIR (1.20 %) (P < 0.01). Wall thickness was also significantly different among the three algorithms with FBP (2.09 mm) demonstrating thicker walls than ASIR (2.00 mm) and MBIR (1.88 mm) (P < 0.01). Airway phantom analysis revealed that MBIR showed the most accurate value for airway measurements. The three algorithms presented different EIs and wall thicknesses, decreasing in the order of FBP, ASIR and MBIR. Thus, care should be taken in selecting the appropriate IR algorithm on quantitative analysis of the lung. (orig.)

26

Standard dose versus low-dose abdominal and pelvic CT: Comparison between filtered back projection versus adaptive iterative dose reduction 3D  

International Nuclear Information System (INIS)

Purpose: To compare the dose and image quality of a standard dose abdominal and pelvic CT with Filtered Back Projection (FBP) to low-dose CT with Adaptive Iterative Dose Reduction 3D (AIDR 3D). Materials and methods: We retrospectively examined the images of 21 patients in the portal phase of an abdominal and pelvic CT scan before and after implementation of AIDR 3D iterative reconstruction. The acquisition length, dose and evaluations of the image quality were compared between standard dose FBP images and low-dose images reconstructed with AIDR 3D and FBP using the Wilcoxon test. Results: The mean acquisition length was similar for both CT scans. There was a significant dose reduction of 49.5% with low-dose CT compared to standard dose CT (mean DLP of 451 mGy.cm versus 892 mGy.cm, P < 0.001). There were no differences in image quality scores between standard dose FBP and low-dose AIDR 3D images (4.6 ± 0.6 versus 4.4 ± 0.6 respectively, P = 0.147). Conclusion: AIDR 3D iterative reconstruction enables a significant reduction in dose of 49.5% to be achieved with abdominal CT scan compared to FBP, whilst maintaining equivalent image quality. (authors)

27

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  

Energy Technology Data Exchange (ETDEWEB)

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

28

Adaptive statistical iterative reconstruction versus filtered back projection in the same patient: 64 channel liver CT image quality and patient radiation dose  

Energy Technology Data Exchange (ETDEWEB)

To compare routine dose liver CT reconstructed with filtered back projection (FBP) versus low dose images reconstructed with FBP and adaptive statistical iterative reconstruction (ASIR). In this retrospective study, patients had a routine dose protocol reconstructed with FBP, and again within 17 months (median 6.1 months), had a low dose protocol reconstructed twice, with FBP and ASIR. These reconstructions were compared for noise, image quality, and radiation dose. Nineteen patients were included. (12 male, mean age 58). Noise was significantly lower in low dose images reconstructed with ASIR compared to routine dose images reconstructed with FBP (liver: p <.05, aorta: p < 0.001). Low dose FBP images were scored significantly lower for subjective image quality than low dose ASIR (2.1 {+-} 0.5, 3.2 {+-} 0.8, p < 0.001). There was no difference in subjective image quality scores between routine dose FBP images and low dose ASIR images (3.6 {+-} 0.5, 3.2 {+-} 0.8, NS).Radiation dose was 41% less for the low dose protocol (4.4 {+-} 2.4 mSv versus 7.5 {+-} 5.5 mSv, p < 0.05). Our initial results suggest low dose CT images reconstructed with ASIR may have lower measured noise, similar image quality, yet significantly less radiation dose compared with higher dose images reconstructed with FBP. (orig.)

Mitsumori, Lee M.; Shuman, William P.; Busey, Janet M.; Kolokythas, Orpheus; Koprowicz, Kent M. [University of Washington School of Medicine, Department of Radiology, Seattle, WA (United States)

2012-01-15

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Does quantification of myocardial perfusion SPECT study differ while image reconstruction is carried out using iteration algorithm instead of filtered back-projection? - preliminary report  

International Nuclear Information System (INIS)

The purpose of this study was to compare the performance of two reconstruction algorithms: conventional filtered back-projection (FBP) and an iterative algorithm -ITW- in quantitative analysis of myocardial perfusion SPECT studies. The defect size and defect severity were assessed on 99mTc - MIBI images reconstructed using both methods and estimation of sensitivity in the detection of perfusion deficits and myocardial viability were performed as well. The study group comprised 43 patients (38 men and 5 women) in the age of 40-73 years (mean 59 years). Heart perfusion scintigraphy was performed following an injection of 22 to 25 mCi 99mTc -MIBI for exercise and rest myocardial perfusion study. Images were reconstructed using FBP and ITW algorithms. Defect size (DS) was quantified by a threshold program and CEqual programme. Defect severity (nadir) was calculated as the ratio of minimal/maximum counts from bull's eye polar map. Coronary arteriography was performed in all patients. Defect size calculated by threshold method on resting images did not differ between reconstruction methods (p=0.61 for cut-off 50% and p = 0.24 for cut-off 60%); defect severity was higher on images reconstructed with ITW (CI0.95 = 2.4% + 5.2% of maximal counts). Sensitivity for detection of heart perfusion defects and estimation of myocardial viability were similar on images reconstructed by both algorithms. (author)

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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 < 0.05). Our results suggest that pancreatic CT images 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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Image quality and radiation dose of low dose coronary CT angiography in obese patients: Sinogram affirmed iterative reconstruction versus filtered back projection  

International Nuclear Information System (INIS)

Purpose: To investigate the image quality and radiation dose of low radiation dose CT coronary angiography (CTCA) using sinogram affirmed iterative reconstruction (SAFIRE) compared with standard dose CTCA using filtered back-projection (FBP) in obese patients. Materials and methods: Seventy-eight consecutive obese patients were randomized into two groups and scanned using a prospectively ECG-triggered step-and-shot (SAS) CTCA protocol on a dual-source CT scanner. Thirty-nine patients (protocol A) were examined using a routine radiation dose protocol at 120 kV and images were reconstructed with FBP (protocol A). Thirty-nine patients (protocol B) were examined using a low dose protocol at 100 kV and images were reconstructed with SAFIRE. Two blinded observers independently assessed the image quality of each coronary segment using a 4-point scale (1 = non-diagnostic, 4 = excellent) and measured the objective parameters image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). Radiation dose was calculated. Results: The coronary artery image quality scores, image noise, SNR and CNR were not significantly different between protocols A and B (all p > 0.05), with image quality scores of 3.51 ± 0.70 versus 3.55 ± 0.47, respectively. The effective radiation dose was significantly lower in protocol B (4.41 ± 0.83 mSv) than that in protocol A (8.83 ± 1.74 mSv, p < 0.01). Conclusion: Compared with standard dose CTCA using FBP, low dose CTCA using SAFIRE can maintain diagnostic image quality with 50% reduction of radiation dose.

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Measurement of vascular wall attenuation: Comparison of CT angiography using model-based iterative reconstruction with standard filtered back-projection algorithm CT in vitro  

International Nuclear Information System (INIS)

Objectives: To compare the performance of model-based iterative reconstruction (MBIR) with that of standard filtered back projection (FBP) for measuring vascular wall attenuation. Study design: After subjecting 9 vascular models (actual attenuation value of wall, 89 HU) with wall thickness of 0.5, 1.0, or 1.5 mm that we filled with contrast material of 275, 396, or 542 HU to scanning using 64-detector computed tomography (CT), we reconstructed images using MBIR and FBP (Bone, Detail kernels) and measured wall attenuation at the center of the wall for each model. We performed attenuation measurements for each model and additional supportive measurements by a differentiation curve. We analyzed statistics using analyzes of variance with repeated measures. Results: Using the Bone kernel, standard deviation of the measurement exceeded 30 HU in most conditions. In measurements at the wall center, the attenuation values obtained using MBIR were comparable to or significantly closer to the actual wall attenuation than those acquired using Detail kernel. Using differentiation curves, we could measure attenuation for models with walls of 1.0- or 1.5-mm thickness using MBIR but only those of 1.5-mm thickness using Detail kernel. We detected no significant differences among the attenuation values of the vascular walls of either thickness (MBIR, P = 0.1606) or among the 3 densities of intravascular contrast material (MBIR, P = 0.8185; Detail kernel, P = 0.0802). Conclusions: Compared with FBP, MBIR reduces both reconstruction blur and image noise simultaneously, facilitates recognition of vascular wall boundaries, and can improve accuracy in measuring wall attenuation.

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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  

International Nuclear Information System (INIS)

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.)

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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  

International Nuclear Information System (INIS)

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.

35

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

Energy Technology Data Exchange (ETDEWEB)

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

36

Measurement of vascular wall attenuation: Comparison of CT angiography using model-based iterative reconstruction with standard filtered back-projection algorithm CT in vitro  

Energy Technology Data Exchange (ETDEWEB)

Objectives: To compare the performance of model-based iterative reconstruction (MBIR) with that of standard filtered back projection (FBP) for measuring vascular wall attenuation. Study design: After subjecting 9 vascular models (actual attenuation value of wall, 89 HU) with wall thickness of 0.5, 1.0, or 1.5 mm that we filled with contrast material of 275, 396, or 542 HU to scanning using 64-detector computed tomography (CT), we reconstructed images using MBIR and FBP (Bone, Detail kernels) and measured wall attenuation at the center of the wall for each model. We performed attenuation measurements for each model and additional supportive measurements by a differentiation curve. We analyzed statistics using analyzes of variance with repeated measures. Results: Using the Bone kernel, standard deviation of the measurement exceeded 30 HU in most conditions. In measurements at the wall center, the attenuation values obtained using MBIR were comparable to or significantly closer to the actual wall attenuation than those acquired using Detail kernel. Using differentiation curves, we could measure attenuation for models with walls of 1.0- or 1.5-mm thickness using MBIR but only those of 1.5-mm thickness using Detail kernel. We detected no significant differences among the attenuation values of the vascular walls of either thickness (MBIR, P = 0.1606) or among the 3 densities of intravascular contrast material (MBIR, P = 0.8185; Detail kernel, P = 0.0802). Conclusions: Compared with FBP, MBIR reduces both reconstruction blur and image noise simultaneously, facilitates recognition of vascular wall boundaries, and can improve accuracy in measuring wall attenuation.

Suzuki, Shigeru, E-mail: shig.suz@gmail.com [Department of Radiology, Saitama Red Cross Hospital, 8-3-33 kamiochiai, Chuo-ku, Saitama 338-0001 (Japan); Department of Radiology, Tokyo Women' s Medical University Medical Center East, 2-1-10 Nishiogu, Arakawa-ku, Tokyo 116-8567 (Japan); Machida, Haruhiko, E-mail: machira@dnh.twmu.ac.jp [Department of Radiology, Tokyo Women' s Medical University Medical Center East, 2-1-10 Nishiogu, Arakawa-ku, Tokyo 116-8567 (Japan); Tanaka, Isao, E-mail: tanakara@dnh.twmu.ac.jp [Department of Radiology, Tokyo Women' s Medical University Medical Center East, 2-1-10 Nishiogu, Arakawa-ku, Tokyo 116-8567 (Japan); Ueno, Eiko, E-mail: e-ueno@ka2.so-net.ne.jp [Department of Radiology, Tokyo Women' s Medical University Medical Center East, 2-1-10 Nishiogu, Arakawa-ku, Tokyo 116-8567 (Japan)

2012-11-15

37

Evaluation of iterative reconstruction (OSEM) versus filtered back-projection for the assessment of myocardial glucose uptake and myocardial perfusion using dynamic PET  

International Nuclear Information System (INIS)

Iterative reconstruction methods based on ordered-subset expectation maximisation (OSEM) has replaced filtered backprojection (FBP) in many clinical settings owing to the superior image quality. Whether OSEM is as accurate as FBP in quantitative positron emission tomography (PET) is uncertain. We compared the accuracy of OSEM and FBP for regional myocardial 18F-FDG uptake and 13NH3 perfusion measurements in cardiac PET. Ten healthy volunteers were studied. Five underwent dynamic 18F-FDG PET during hyperinsulinaemic-euglycaemic clamp, and five underwent 13NH3 perfusion measurement during rest and adenosine-induced hyperaemia. Images were reconstructed using FBP and OSEM ± an 8-mm Gaussian post-reconstruction filter. Filtered and unfiltered images showed agreement between the reconstruction methods within ±2SD in Bland-Altman plots of Ki values. The use of a Gaussian filter resulted in a systematic underestimation of Ki in the filtered images of 11%. The mean deviation between the reconstruction methods for both unfiltered and filtered images was 1.3%. Agreement within ±2SD between the methods was demonstrated for perfusion rate constants up to 2.5 min-1, corresponding to a perfusion of 3.4 ml g-1 min-1. The mean deviation between the two methods for unfiltered data was 2.7%, and for filtered data, 5.3%. The 18F-FDG uptake rate constants showed excellent agreement between the two reconstruction methods. In the perfusion range up to 3.4 ml g-1 min-1, agreement between 13NH3 perfusion obtained with OSEM and FBP was acceptable. The use of OSEM for measurement of perfusion values higher than 3.4 ml g-1 min-1 requires further evaluation. (orig.)

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Experimental evaluation of iterative reconstruction versus filtered back projection for 3D [15O]water PET activation studies using statistical parametric mapping analysis.  

Science.gov (United States)

Iterative reconstructions are increasingly used for clinical PET studies owing to the better noise properties compared with filtered backprojection (FBP). The purpose of the present study was to compare ordered subsets expectation maximization (OSEM) iterative reconstruction with FBP as input for statistical parametric mapping (SPM) analysis of PET activation studies. Two phantom studies were performed simulating both motor and cognitive tasks and acquiring data with both high and low statistics. In contrast to clinical studies, where no a priori information is known, phantom studies allow for an accurate and detailed comparison between different reconstruction techniques. The significance of "activations" during "tasks" was determined using SPM99 software. Using region of interest analysis of SPM results, it was found that the maximum and average t values within each hot spot of the phantom were higher for OSEM than for FBP. In addition, OSEM4 x 16 (4 iterations, 16 subsets) produced fewer false-positive voxels than FBP, OSEM1 x 16 and OSEM2 x 16. In conclusion, for PET activation studies use of OSEM4 x 16 seems to give the best tradeoff between signal detection and noise reduction. PMID:12880842

Mesina, Catalina T; Boellaard, Ronald; Jongbloed, Geurt; van der Vaart, Aad W; Lammertsma, Adriaan A

2003-07-01

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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.)

40

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  

Energy Technology Data Exchange (ETDEWEB)

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

 
 
 
 
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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  

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

42

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.)

43

Feasible Dose Reduction in Routine Chest Computed Tomography Maintaining Constant Image Quality Using the Last Three Scanner Generations: From Filtered Back Projection to Sinogram-affirmed Iterative Reconstruction and Impact of the Novel Fully Integrated Detector Design Minimizing Electronic Noise  

Science.gov (United States)

Objective: The aim of the present study was to evaluate a dose reduction in contrast-enhanced chest computed tomography (CT) by comparing the three latest generations of Siemens CT scanners used in clinical practice. We analyzed the amount of radiation used with filtered back projection (FBP) and an iterative reconstruction (IR) algorithm to yield the same image quality. Furthermore, the influence on the radiation dose of the most recent integrated circuit detector (ICD; Stellar detector, Siemens Healthcare, Erlangen, Germany) was investigated. Materials and Methods: 136 Patients were included. Scan parameters were set to a thorax routine: SOMATOM Sensation 64 (FBP), SOMATOM Definition Flash (IR), and SOMATOM Definition Edge (ICD and IR). Tube current was set constantly to the reference level of 100 mA automated tube current modulation using reference milliamperes. Care kV was used on the Flash and Edge scanner, while tube potential was individually selected between 100 and 140 kVp by the medical technologists at the SOMATOM Sensation. Quality assessment was performed on soft-tissue kernel reconstruction. Dose was represented by the dose length product. Results: Dose-length product (DLP) with FBP for the average chest CT was 308 mGy*cm ± 99.6. In contrast, the DLP for the chest CT with IR algorithm was 196.8 mGy*cm ± 68.8 (P = 0.0001). Further decline in dose can be noted with IR and the ICD: DLP: 166.4 mGy*cm ± 54.5 (P = 0.033). The dose reduction compared to FBP was 36.1% with IR and 45.6% with IR/ICD. Signal-to-noise ratio (SNR) was favorable in the aorta, bone, and soft tissue for IR/ICD in combination compared to FBP (the P values ranged from 0.003 to 0.048). Overall contrast-to-noise ratio (CNR) improved with declining DLP. Conclusion: The most recent technical developments, namely IR in combination with integrated circuit detectors, can significantly lower radiation dose in chest CT examinations. PMID:25161807

Ebner, Lukas; Knobloch, Felix; Huber, Adrian; Landau, Julia; Ott, Daniel; Heverhagen, Johannes T; Christe, Andreas

2014-01-01

44

A New Back-Projection Algorithm For Spotlight-Mode SAR And ISAR  

Science.gov (United States)

Spotlight mode SAR and ISAR are microwave imaging systems that are used to obtain high resolution reflectivity images by processing data obtained from many different perspective views of a target. Usually a chirp signal with a high time-bandwidth product is transmitted and the returned signal from the target is coherently demodulated and then sampled, providing polar samples of the 2-D Fourier transform of the target reflectivity. The most commonly used image reconstruction algorithm then interpolates the polar data to a Cartesian grid and applies a 2-D FFT. An alternative reconstruction algorithm, called convolution-back-projection, first filters and inverse transforms each demodulated return using a 1-D FFT and then back-projects the result. In this paper we propose a simplified back-projection algorithm in which the filtered projections are obtained automatically by choosing the radar waveform to be the impulse response of the desired filter. The necessary filtering is then accomplished through the physical mechanism of the waveform reflecting off the target, which is described by a convolution. A parallel processing architecture is proposed for the back-projection step and its computational and memory requirements are analyzed. Finally, we describe a second potential method for obtaining projections, which assumes a conventional linear FM waveform.

Arikan, Orhan; Munson, David C.

1989-05-01

45

Estimating brain network activity through back-projection of ICA components to GLM maps.  

Science.gov (United States)

Independent component analysis (ICA) is a data-driven approach frequently used in neuroimaging to model functional brain networks. Despite ICA's increasing popularity, methods for replicating published ICA components across independent datasets have been underemphasized. Traditionally, the task-dependent activation of a component is evaluated by first back-projecting the component to a functional MRI (fMRI) dataset, then performing general linear modeling (GLM) on the resulting timecourse. We propose the alternative approach of back-projecting the component directly to univariate GLM results. Using a sample of 37 participants performing the Multi-Source Interference Task, we demonstrate these two approaches to yield identical results. Furthermore, while replicating an ICA component requires back-projection of component beta-values (?s), components are typically depicted only by t-scores. We show that while back-projection of component ?s and t-scores yielded highly correlated results (?=0.95), group-level statistics differed between the two methods. We conclude by stressing the importance of reporting ICA component ?s, rather than component t-scores, so that functional networks may be independently replicated across datasets. PMID:24513233

James, G Andrew; Tripathi, Shanti Prakash; Kilts, Clinton D

2014-04-01

46

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

47

UV Fluorescence Photography of Works of Art : Replacing the Traditional UV Cut Filters with Interference Filters  

Directory of Open Access Journals (Sweden)

Full Text Available For many years filters like the Kodak Wratten E series, or the equivalent Schneider B+W 415, were used as standard UV cut filters, necessary to obtain good quality on UV Fluorescence photography. The only problem with the use of these filters is that, when they receive the UV radiation that they should remove, they present themselves an internal fluorescence as side effect, that usually reduce contrast and quality on the final image. This article presents the results of our experiences on using some innovative filters, that appeared available on the market in recent years, projected to adsorb UV radiation even more efficiently than with the mentioned above pigment based standard filters: the interference filters for UV rejection (and, usually, for IR rejection too manufactured using interference layers, that present better results than the pigment based filters. The only problem with interference filters type is that they are sensitive to the rays direction and, because of that, they are not adequate to wide-angle lenses. The internal fluorescence for three filters: the B+W 415 UV cut (equivalent to the Kodak Wratten 2E, pigment based, the B+W 486 UV IR cut (an interference type filter, used frequently on digital cameras to remove IR or UV and the Baader UVIR rejection filter (two versions of this interference filter were used had been tested and compared. The final quality of the UV fluorescence images seems to be of a superior quality when compared to the images obtained with classic filters.

Luís BRAVO PEREIRA

2010-09-01

48

Traditional Tracking with Kalman Filter on Parallel Architectures  

CERN Document Server

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 technologies today include Intel's Xeon Phi and GPGPUs. Track finding and fitting is one of the most computationally challenging problems for event reconstruction in particle physics. At the High Luminosity LHC, for example, this will be by far the dominant problem. The most common track finding techniques in use today are however those based on the Kalman Filter. Significant experience has been accumulated with these techniques on real tracking detector systems, both in the trigger and offline. We report the results of our investigations into the p...

Cerati, Giuseppe; Lantz, Steven; MacNeill, Ian; McDermott, Kevin; Riley, Dan; Tadel, Matevz; Wittich, Peter; Wuerthwein, Frank; Yagil, Avi

2014-01-01

49

An improved back projection algorithm of ultrasound tomography  

Energy Technology Data Exchange (ETDEWEB)

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 [Institute of Particle and Two-phase Flow Measurement, University of Shanghai for Science and Technology, Shanghai 200093 (China)

2014-04-11

50

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

51

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

52

Investigating the 2010 Moro Gulf deep earthquake sequence using the continuous back-projection technique  

Science.gov (United States)

Deep earthquakes make up approximately one-quarter of all earthquakes, yet current understanding of mechanisms for deep (300-700 km) earthquake generation fails to explain why deep range earthquakes occur at all. Various mechanisms, such as metastable phase change, have been proposed, however, there is a lack of observational constraints on the properties of deep earthquakes, which deter our understanding. In order to progress our knowledge of the deep earth, such as its chemistry, mineralogy, and dynamics, robust constraints on the mechanisms of deep earthquakes are required. The goal of this project is to explore the mechanism(s) behind deep earthquakes through studying the 2010 Moro Gulf deep earthquake sequence using a continuous back-projection technique. The Moro Gulf sequence features a 'triplet' of earthquakes with hypocentral depths between 585 and 640 km. The triplet earthquakes are particularly unusual, because they are large magnitude events (Mw7.3, 7.6, and 7.4) that occurred within an hour and a half of each other, which does not agree with the Gutenberg-Richter relationship. No other triplet sequences of this magnitude have been recorded within such a short time period. Another anomalous characteristic of these earthquakes is the emergent waveforms of the sequence. Typically, deep earthquakes have impulsive waveforms, which is thought to be associated with more rapid stress drop than shallow events, for which the stress drop occurs more gradually. The back-projection technique is an efficient method to constrain earthquake rupture properties, such as rupture direction, rupture speed, location, timing, and relative energy release of an earthquake. It requires high-quality data from a dense network of seismic stations covering a large area, and we use data from the High-Sensitivity Seismograph Network (Hi-net) in Japan and US Transportable Array (US-TA). The technique creates a grid of potential source locations around the hypocenter. The seismograms are time-shifted and stacked at each grid point. The data from the three earthquakes are filtered to a frequency range of 0.8-2 Hz in order to maximize the resolution from the back-projection, and to capture the first arriving P-waves in the waveforms. Another crucial step is aligning the P- and PKP(DF)-phases for Hi-net and US-TA, respectively. Since alignment has a strong influence on the back-projection, we aligned the US-TA phases using an aftershock because smaller magnitude earthquakes often improve alignment. The back-projection technique has been used in previous studies to investigate both shallow (0-100 km) and intermediate-depth (100-300 km) earthquakes. Using back-projection on deep earthquakes is expected to increase depth resolution results from the incorporation of depth phases, that, when combined with downward take-off phases, reveal a more accurate hypocentral depth. Also, better spatial resolution is achieved by the combination of the Hi-net and US-TA arrays, which overlap signals at a more accurate location of the rupture. Back-projection analysis of the Moro Gulf sequence is expected to provide a detailed rupture process of these deep events with high depth and spatial resolution.

Kowalke, S. M.; Kiser, E.; Ishii, M.

2011-12-01

53

An accelerated threshold-based back-projection algorithm for Compton camera image reconstruction  

International Nuclear Information System (INIS)

Purpose: Compton camera imaging (CCI) systems are currently under investigation for radiotherapy dose reconstruction and verification. The ability of such a system to provide real-time images during dose delivery will be limited by the computational speed of the image reconstruction algorithm. In this work, the authors present a fast and simple method by which to generate an initial back-projected image from acquired CCI data, suitable for use in a filtered back-projection algorithm or as a starting point for iterative reconstruction algorithms, and compare its performance to the current state of the art. Methods: Each detector event in a CCI system describes a conical surface that includes the true point of origin of the detected photon. Numerical image reconstruction algorithms require, as a first step, the back-projection of each of these conical surfaces into an image space. The algorithm presented here first generates a solution matrix for each slice of the image space by solving the intersection of the conical surface with the image plane. Each element of the solution matrix is proportional to the distance of the corresponding voxel from the true intersection curve. A threshold function was developed to extract those pixels sufficiently close to the true intersection to generate a binary intersection curve. This process is repeated for each image plane for each CCI detector event, resulting in a three-dimensional back-projection image. The performance of this algorithm was tested against a marching algorithm known for speed and accuracy. Results: The threshold-based algorithm was found to be approximately four times faster than the current state of the art with minimal deficit to image quality, arising from the fact that a generically applicable threshold function cannot provide perfect results in all situations. The algorithm fails to extract a complete intersection curve in image slices near the detector surface for detector event cones having axes nearly parallel to the image plane. This effect decreases the sum of the image, thereby also affecting the mean, standard deviation, and SNR of the image. All back-projected events associated with a simulated point source intersected the voxel containing the source and the FWHM of the back-projected image was similar to that obtained from the marching method. Conclusions: The slight deficit to image quality observed with the threshold-based back-projection algorithm described here is outweighed by the 75% reduction in computation time. The implementation of this method requires the development of an optimum threshold function, which determines the overall accuracy of the method. This makes the algorithm well-suited to applications involving the reconstruction of many large images, where the time invested in threshold development is offset by the decreased image reconstruction time. Implemented in a parallel-computing environment, the threshold-based algorithm has the potential to provide real-time dose verification for radiation therapy.

54

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

55

A Multi-Scale Weighted Back Projection Imaging Technique for Ground Penetrating Radar Applications  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, we propose a new ground penetrating radar (GPR imaging technique based on multi-scale weighted back projection (BP processing. Firstly, the whole imaging region is discretized by large scale and low-resolution imaging result is obtained by using traditional BP imaging technique. Secondly, the potential targets regions (PTR are delineated from low-resolution imaging result by using intensity detection method. In the PTR, small scale discretization is implemented and higher resolution imaging result is obtained by using weighted BP imaging technique. A weight factor is designed by analyzing the statistical characteristics of scattering data on the time-delay curve. The above “discretization-imaging-PTR delineation” processing continues until the imaging resolution reaches the specified requirement. In the multi-scale imaging result, the resolution in other regions is not as high as that in PTR. This algorithm can get higher resolution imaging results with much lower computation compared with traditional BP imaging algorithm. The simulation of this algorithm is processed and experimental results validate the feasibility of this method.

Wentai Lei

2014-06-01

56

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

Science.gov (United States)

We devised a new field-of-view autotracking method for online tomography reconstruction based on a cross-correlation between a pair of neighbours, called back-projected ray images, among a specimen tilt sequence. One ray image is calculated through normal filtered back-projection only in the cross-sectional plane from each projection image. This ray-image matching can reliably track the field-of-view because a pair of neighbouring ray images mostly cross-correlates at the existing three-dimensional object position. Online experiments using real specimens resulted in successful autotracking performance with high accuracy, and online tomograms were obtained immediately after the final tracking at the last tilting angle. PMID:24938231

Tomonaga, Sachihiko; Baba, Misuzu; Yamazaki, Sadao; Baba, Norio

2014-10-01

57

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

58

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

59

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

60

Decoding using back-project algorithm from coded image in ICF  

International Nuclear Information System (INIS)

The principle of the coded imaging and its decoding in inertial confinement fusion is described simply. The authors take ring aperture microscope for example and use back-project (BP) algorithm to decode the coded image. The decoding program has been performed for numerical simulation. Simulations of two models are made, and the results show that the accuracy of BP algorithm is high and effect of reconstruction is good. Thus, it indicates that BP algorithm is applicable to decoding for coded image in ICF experiments

 
 
 
 
61

Acoustic Image Reconstruction from Adaptive Microphone Array Signals Using Back Projection  

Science.gov (United States)

We propose a new technique for acoustic imaging that employs a back-projection algorithm to process signals from a static ultrasonic microphone array. To obtain the projection data for a target, we integrate the time distribution of received signal powers gained by pulse compression with the Radon transform of a sound field in polar coordinates. The proposed method is expected to improve angular resolution. In this paper, we describe the principle of this algorithm, explaining how it improves the resolution and performs better than conventional methods. Deconvolution is used to improve the quality of the images obtained. We have conducted computer simulations to verify the performance of the proposed algorithm. From these simulations, the angular resolution of the images achieved by the proposed technique was shown to be double that obtained by a conventional beamforming method. In our future work, we plan to conduct experiments with real environments and investigate the theoretical aspects of the proposed method more deeply.

Mizutani, Kyohei; Sugimoto, Masanori; Hashizume, Hiromichi

62

Measurement of population receptive fields in human early visual cortex using back-projection tomography.  

Science.gov (United States)

Properties of human visual population receptive fields (pRFs) are currently estimated by performing measurements of visual stimulation using functional magnetic resonance imaging (fMRI), and then fitting the results using a predefined model shape for the pRF. Various models exist and different models may be appropriate under different circumstances, but the validity of the models has never been verified, suggesting the need for a model-free approach. Here, we demonstrate that pRFs can be directly reconstructed using a back-projection-tomography approach that requires no a priori model. The back-projection method involves sweeping thin contrast-defined bars across the visual field whose orientation and direction is rotated through 0°-180° in discrete increments. The measured fMRI time series within a cortical location can be approximated as a projection of the pRF along the long axis of the bar. The signals produced by a set of bar sweeps encircling the visual field form a sinogram. pRFs were reconstructed from these sinograms with a novel scheme that corrects for the blur introduced by the hemodynamic response and the stimulus-bar width. pRF positions agree well with the conventional model-based approach. Notably, a subset of the reconstructed pRFs shows significant asymmetry for both their excitatory and suppressive regions. Reconstructing pRFs using the tomographic approach is a fast, reliable, and accurate way to noninvasively estimate human pRF parameters and visual-field maps without the need for any a priori shape assumption. PMID:24453343

Greene, Clint A; Dumoulin, Serge O; Harvey, Ben M; Ress, David

2014-01-01

63

Visual Effects for Stereoscopic 3D Contents: Experiences from the Don't Look Back-project  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Visual effects for stereoscopic 3D contents, experiences from the Don't Look Back-project is a description of workflow and phases I went through by making of visual effects on stereoscopic 3D footage filmed earlier in 2010. Work includes two shots from the Don't Look Back-project, where I had opportunity to make computer generated imagery and visual effects. Stereoscopic three dimensional (s3D) refers in cinema to the films which are seen with specific glasses on. S3D material is create...

Matilainen, Tapio

2012-01-01

64

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.

65

Radiation dose reduction in time-resolved CT angiography using highly constrained back projection reconstruction  

International Nuclear Information System (INIS)

Recently dynamic, time-resolved three-dimensional computed tomography angiography (CTA) has been introduced to the neurological imaging community. However, the radiation dose delivered to patients in time-resolved CTA protocol is a high and potential risk associated with the ionizing radiation dose. Thus, minimizing the radiation dose is highly desirable for time-resolved CTA. In order to reduce the radiation dose delivered during dynamic, contrast-enhanced CT applications, we introduce here the CT formulation of HighlY constrained back PRojection (HYPR) imaging. We explore the radiation dose reduction approaches of both acquiring a reduced number of projections for each image and lowering the tube current used during acquisition. We then apply HYPR image reconstruction to produce image sets at a reduced patient dose and with low image noise. Numerical phantom experiments and retrospective analysis of in vivo canine studies are used to assess the accuracy and quality of HYPR reduced dose image sets and validate our approach. Experimental results demonstrated that a factor of 6-8 times radiation dose reduction is possible when the HYPR algorithm is applied to time-resolved CTA exams.

66

Tomographic Back-Projection Algorithm for ``Incomplete'' Compton X-Rays Detectors  

Science.gov (United States)

A "Compton" detector finds the direction of an X-ray by letting it interact with a gaseous, liquid or thin solid material (Tracker) and employing no collimators. This paper takes into account the case of an "incomplete" solid Tracker where the recoiling electron travels only a few dozen microns and cannot be followed. However, impact positions and incoming and outgoing energies are measured. In this situation, exploiting the Compton Scattering formula, one is only able to identify a cone whose surface the X-ray belongs to. On the other hand, Compton tomography luckily requires only a few views (for example rotating the apparatus in just four positions around the subject), as the "electronic collimation" that takes place in each position already extracts X-rays coming from many directions. A back-projection algorithm that combines the reconstructed "cones" in space, weighed according to the Klein-Nishina formula, has been applied to the special case of small animal SPECT (Single Photon Emission Computed Tomography). Here the source is close to the detector, every imaged point in space is calculated from many rays that are emitted at different angles, and the algorithm totally differs from that of the Compton imaging in Astronomy. Tomography reconstruction has been validated by employing simulated data, generated using GEANT4 that includes the Doppler Broadening in the energies of scattered photons, which is due to moving non-free electrons. Space resolution has been assessed.

Fontana, Cristiano Lino; Baldazzi, Giuseppe; Battistella, Andrea; Bello, Michele; Bollini, Dante; Galli, Marcello; Moschini, Giuliano; Zampa, Gianluigi; Zampa, Nicola; Rossi, Paolo

2011-06-01

67

Radiation dose reduction in time-resolved CT angiography using highly constrained back projection reconstruction  

Energy Technology Data Exchange (ETDEWEB)

Recently dynamic, time-resolved three-dimensional computed tomography angiography (CTA) has been introduced to the neurological imaging community. However, the radiation dose delivered to patients in time-resolved CTA protocol is a high and potential risk associated with the ionizing radiation dose. Thus, minimizing the radiation dose is highly desirable for time-resolved CTA. In order to reduce the radiation dose delivered during dynamic, contrast-enhanced CT applications, we introduce here the CT formulation of HighlY constrained back PRojection (HYPR) imaging. We explore the radiation dose reduction approaches of both acquiring a reduced number of projections for each image and lowering the tube current used during acquisition. We then apply HYPR image reconstruction to produce image sets at a reduced patient dose and with low image noise. Numerical phantom experiments and retrospective analysis of in vivo canine studies are used to assess the accuracy and quality of HYPR reduced dose image sets and validate our approach. Experimental results demonstrated that a factor of 6-8 times radiation dose reduction is possible when the HYPR algorithm is applied to time-resolved CTA exams.

Supanich, Mark; Tao Yinghua; Nett, Brian; Mistretta, Charles; Chen Guanghong [Department of Medical Physics, University of Wisconsin in Madison, 1111 Highland Avenue, Madison, WI, 53705 (United States); Pulfer, Kari; Turski, Patrick; Rowley, Howard [Department of Radiology, University of Wisconsin in Madison, 600 Highland Avenue, Madison, WI, 53792 (United States); Hsieh Jiang [GE Medical Systems, 300 N, Grandview Blvd., Waukesha, WI 53188 (United States)], E-mail: gchen7@wisc.edu

2009-07-21

68

Parathyroid scintigraphy - benefit of early and late SPECT with iterative reconstruction (IR) versus filtered back projection (FBP)  

International Nuclear Information System (INIS)

Full text: The published literature is conflicting on the benefit of Parathyroid SPECT. This study evaluates the incremental benefit of SPECT over planar imaging, comparing both the timing of SPECT and the processing technique used. Over 1 year, patients referred for parathyroid scintigraphy were studied with conventional dual tracer and dual phase planar imaging using 50 MBq of Tc-99m-pertechnetate and 800 MBq of Tc-99m MIBI. SPECT was performed both after the initial and 2 hour planars, and processed using both PBP and IR. All studies were randomised and read as planar, planar+FBP then planar+FBP+IR for both early and late SPECT by 2 blinded readers. Focal abnormalities were scored on a 5 point scale, with scores of 4 and 5 being called positive. In cases of observer disagreement a third blinded reader was used. Surgical follow up was available in 16 of 33 patients. 2 were surgically non curative and excluded (including one probable scintigraphic mediastinal adenoma not located at surgery). Sensitivity and ROC analyses were performed to evaluate incremental benefit of FBP and IR SPECT over planars. No significant difference was found between Early and Late SPECT. ROC analysis of individual readers showed improved accuracy of SPECT over planars for one of the two readers. IR SPECT improves sensitivity without loss of specificity compared to planar imaging. Late SPECT shows no additional benefit. Copyright (2002) The Australian and New Zealand Society of Nuclear Medicine Inc

69

Autofocus and analysis of geometrical errors within the framework of fast factorized back-projection  

Science.gov (United States)

This paper describes a Fast Factorized Back-Projection (FFBP) formulation that includes a fully integrated autofocus algorithm, i.e. the Factorized Geometrical Autofocus (FGA) algorithm. The base-two factorization is executed in a horizontal plane, using a Merging (M) and a Range History Preserving (RHP) transform. Six parameters are adopted for each sub-aperture pair, i.e. to establish the geometry stage-by-stage via triangles in 3-dimensional space. If the parameters are derived from navigation data, the algorithm is used as a conventional processing chain. If the parameters on the other hand are varied from a certain factorization step and forward, the algorithm is used as a joint image formation and autofocus strategy. By regulating the geometry at multiple resolution levels, challenging defocusing effects, e.g. residual space-variant Range Cell Migration (RCM), can be corrected. The new formulation also serves another important purpose, i.e. as a parameter characterization scheme. By using the FGA algorithm and its inverse, relations between two arbitrary geometries can be studied, in consequence, this makes it feasible to analyze how errors in navigation data, and topography, affect image focus. The versatility of the factorization procedure is demonstrated successfully on simulated Synthetic Aperture Radar (SAR) data. This is achieved by introducing different GPS/IMU errors and Focus Target Plane (FTP) deviations prior to processing. The characterization scheme is then employed to evaluate the sensitivity, to determine at what step the autofocus function should be activated, and to decide the number of necessary parameters at each step. Resulting FGA images are also compared to a reference image (processed without errors and autofocus) and to a defocused image (processed without autofocus), i.e. to validate the novel approach further.

Torgrimsson, Jan; Dammert, Patrik; Hellsten, Hans; Ulander, Lars M. H.

2014-06-01

70

Influence of filtering on the quality nuclear-tomography image  

International Nuclear Information System (INIS)

In the paper is analysed the possibility of the improvements quality of a tomography image applying a deblurring (RL, SL) and a noise reduction filter (Wiener filter). The base of the analyse is Fourier Back Projection method for reconstruction applied in emission tomography. The choice of the optimum filter function is certainly an important factor. The noise data have been filtered, using different filters, and obtained images were compared (author)

71

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

72

Images of Gravitational and Magnetic Phenomena Derived from Two-dimensional Back-projection Doppler Tomography of Interacting Binary Stars  

Science.gov (United States)

We have used two-dimensional back-projection Doppler tomography as a tool to examine the influence of gravitational and magnetic phenomena in interacting binaries that undergo mass transfer from a magnetically active star onto a non-magnetic main-sequence star. This multitiered 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? 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 methods used to extract the physical properties of the emission sources directly from the velocity images, including S-wave analysis, the creation of simulated velocity tomograms from hydrodynamic simulations, and the use of synthetic spectra with tomography to sequentially extract the separate sources of emission from the velocity image. In summary, the tomography images have revealed results that cannot be explained solely by gravitational effects: chromospheric emission moving with the mass-losing star, a gas stream deflected from the gravitational trajectory, and alternating behavior between stream state and disk state. Our results demonstrate that magnetic effects cannot be ignored in these interacting binaries.

Richards, Mercedes T.; Cocking, Alexander S.; Fisher, John G.; Conover, Marshall J.

2014-11-01

73

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

74

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

75

Implicit Kalman filtering  

Science.gov (United States)

For an implicitly defined discrete system, a new algorithm for Kalman filtering is developed and an efficient numerical implementation scheme is proposed. Unlike the traditional explicit approach, the implicit filter can be readily applied to ill-conditioned systems and allows for generalization to descriptor systems. The implementation of the implicit filter depends on the solution of the congruence matrix equation (A1)(Px)(AT1) = Py. We develop a general iterative method for the solution of this equation, and prove necessary and sufficient conditions for convergence. It is shown that when the system matrices of an implicit system are sparse, the implicit Kalman filter requires significantly less computer time and storage to implement as compared to the traditional explicit Kalman filter. Simulation results are presented to illustrate and substantiate the theoretical developments.

Skliar, M.; Ramirez, W. F.

1997-01-01

76

Semicircular microstrip low pass filter  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents semicircular microstrip low pass filter with the sharp rejection and wide stop band. The proposed filter design is based on the calculation of filter parameters from traditional hi-lo impedance method and is available in the literature of microstrip filter. To further improve the design performance, high impedance lines are magnetically coupled, resulting an attenuation pole near -3dB cut off point of the filter. This design gives insight in designing a low pass filter with reduced size of an arbitrary geographical shape.

Kumud Ranjan Jha

2008-08-01

77

Traditional media.  

Science.gov (United States)

Traditional folk media (such as folk theater, dance and textile arts) offer health program managers a potentially powerful method of reaching rural villagers. While modern mass media (such as radio, television, printed matter) may extend messages to larger audiences at lower cost per person reached, their dependence on centralized, urban facilities and staff and their need for uniform, fixed messages often make them less responsive to local situations and specific audience needs. Traditional media use local language and symbols in a format which is familiar, credible and accessible to rural villagers. To be truly appropriate, traditional media (like other technologies) must be adapted to the overall approach, message, and intended audience with which they are used. Integration with modern media may be successful but must be approached cautiously. Evaluation is critical both for adjusting the specific project and for better assessment of the net effectiveness of folk media communication strategies. With appropriate matching of a strategy's central components and thorough consideration of implemenatation and management issues (integration, training, evaluation, funding), traditional fold media can become an extremely effective means of communicating health information. This issue outlines the guidelines for use of traditional media in health communication activities, with special emphasis on live drama puppetry, song and dance, storytelling and proverbs, and pictures, PMID:12268713

1987-01-01

78

Traditional Ay  

The applicant company is the only company producing „Traditional Ayrshire ... \\butterfat content can range from 3.9% to 4.4% which passes into the high fat ... \\resultant solid curd within the mixture is cut into ¼inch cubes by hand with knives.

79

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

80

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

 
 
 
 
81

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

82

Electromechanical Frequency Filters  

Science.gov (United States)

Frequency filters select signals with a frequency inside a definite frequency range or band from signals outside this band, traditionally afforded by a combination of L-C-resonators. The fundamental principle of all modern frequency filters is the constructive interference of travelling waves. If a filter is set up of coupled resonators, this interference occurs as a result of the successive wave reflection at the resonators' ends. In this case, the center frequency f c of a filter, e.g., set up of symmetrical ?/2-resonators of length 1, is given by f_c = f_r = v_{ph}/? = v_{ph}/2l , where v ph is the phase velocity of the wave. This clearly shows the big advantage of acoustic waves for filter applications in comparison to electro-magnetic waves. Because v ph of acoustic waves in solids is about 104-105 smaller than that of electro-magnetic waves, much smaller filters can be realised. Today, piezoelectric materials and processing technologies exist that electromechanical resonators and filters can be produced in the frequency range from 1 kHz up to 10 GHz. Further requirements for frequency filters such as low losses (high resonator Q) and low temperature coefficients of frequency constants can also be fulfilled with these filters. Important examples are quartz-crystal resonators and filters (1 kHz-200 MHz) as discussed in Chap. 2, electromechanical channel filters (50 kHz and 130 kHz) for long-haul communication systems as discussed in this section, surface acoustic wave (SAW) filters (20 MHz-5 GHz), as discussed in Chap. 14, and thin film bulk acoustic resonators (FBAR) and filters (500 MHz-10 GHz), as discussed in Chap. 15.

Wersing, W.; Lubitz, K.

83

The diffuse ensemble filter  

Directory of Open Access Journals (Sweden)

Full Text Available A new class of ensemble filters, called the Diffuse Ensemble Filter (DEnF, is proposed in this paper. The DEnF assumes that the forecast errors orthogonal to the first guess ensemble are uncorrelated with the latter ensemble and have infinite variance. The assumption of infinite variance corresponds to the limit of "complete lack of knowledge" and differs dramatically from the implicit assumption made in most other ensemble filters, which is that the forecast errors orthogonal to the first guess ensemble have vanishing errors. The DEnF is independent of the detailed covariances assumed in the space orthogonal to the ensemble space, and reduces to conventional ensemble square root filters when the number of ensembles exceeds the model dimension. The DEnF is well defined only in data rich regimes and involves the inversion of relatively large matrices, although this barrier might be circumvented by variational methods. Two algorithms for solving the DEnF, namely the Diffuse Ensemble Kalman Filter (DEnKF and the Diffuse Ensemble Transform Kalman Filter (DETKF, are proposed and found to give comparable results. These filters generally converge to the traditional EnKF and ETKF, respectively, when the ensemble size exceeds the model dimension. Numerical experiments demonstrate that the DEnF eliminates filter collapse, which occurs in ensemble Kalman filters for small ensemble sizes. Also, the use of the DEnF to initialize a conventional square root filter dramatically accelerates the spin-up time for convergence. However, in a perfect model scenario, the DEnF produces larger errors than ensemble square root filters that have covariance localization and inflation. For imperfect forecast models, the DEnF produces smaller errors than the ensemble square root filter with inflation. These experiments suggest that the DEnF has some advantages relative to the ensemble square root filters in the regime of small ensemble size, imperfect model, and copious observations.

X. Yang

2009-07-01

84

Keeping Tradition  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Chinese dumplings such as Jiao Zi and Bao Zi are two of the popular traditional foods in Asia. They are usually made from wheat flour dough (rice flour or starch is sometimes used) that contains fillings. They can be steamed, boiled and fried and are consumed either as a main meal or dessert. As these tasty dumplings are easy to prepare, they have become one of Asia's fastest growing products in the frozen and ready-to-eat sector.

Zenhong, C.; Buwalda, P. L.

2011-01-01

85

Adaptive multiple filtering  

Science.gov (United States)

The method described represents an attractive compromise between the use of a single filter for a number of image distortions and one filter for each image or distortion of an image. The goal of this work is the generation of a number of filters, each of them being able to recognize a number of distortions. One of the main problems of the filter design is its high sensitivity to internal noise of the system, optical aberrations, etc. In this work, the most common case of image distortion invariance has been considered together with system noise invariance. The simulation results indicate the absence of a false alarm and good identification. The filter generation is based on a learning process in an electro-optical pattern recognition system. The genetic algorithm serves as an optimization method. A binary filter has been selected as the spatial filter. The comparison between a traditional matched spatial complex filter and this adaptive binary filter performance indicates the significant benefits of the latter. Statistical tools were used to estimate and compare the significance of the difference between the output average of a rejection and recognition image sets.

Billert, Oleg; Singher, Liviu

2002-01-01

86

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

87

Statistically-Efficient Filtering in Impulsive Environments: Weighted Myriad Filters  

Directory of Open Access Journals (Sweden)

Full Text Available Linear filtering theory has been largely motivated by the characteristics of Gaussian signals. In the same manner, the proposed Myriad Filtering methods are motivated by the need for a flexible filter class with high statistical efficiency in non-Gaussian impulsive environments that can appear in practice. Myriad filters have a solid theoretical basis, are inherently more powerful than median filters, and are very general, subsuming traditional linear FIR filters. The foundation of the proposed filtering algorithms lies in the definition of the myriad as a tunable estimator of location derived from the theory of robust statistics. We prove several fundamental properties of this estimator and show its optimality in practical impulsive models such as the α-stable and generalized-t. We then extend the myriad estimation framework to allow the use of weights. In the same way as linear FIR filters become a powerful generalization of the mean filter, filters based on running myriads reach all of their potential when a weighting scheme is utilized. We derive the “normal” equations for the optimal myriad filter, and introduce a suboptimal methodology for filter tuning and design. The strong potential of myriad filtering and estimation in impulsive environments is illustrated with several examples.

Juan G. Gonzalez

2002-01-01

88

Cold Crystal Reflector Filter Concept  

CERN Document Server

In this paper the theoretical concept of a cold crystal reflector filter will be presented. The aim of this concept is to balance the shortcoming of the traditional cold polycrystalline reflector filter, which lies in the significant reduction of the neutron flux right above (in energy space) or right below (wavelength space) the first Bragg edge.

Muhrer, G

2014-01-01

89

Air filter  

International Nuclear Information System (INIS)

An air filter consists of an upright cylinder of corrugated or pleated filter fabric, joined at its upper end to a tubular right-angled elbow. The open end of the elbow includes an internal lip seal, so the elbow can be slid onto a horizontal spigot in an air filter unit. The filter can be cleaned by subjecting the fabric to a reverse pressure pulse from a nozzle. The construction facilitates removal of the filter into a plastic bag secured round a frame behind a door, when the unit is used to filter radioactive dust from air. (author)

90

Water Filters  

Science.gov (United States)

The Aquaspace H2OME Guardian Water Filter, available through Western Water International, Inc., reduces lead in water supplies. The filter is mounted on the faucet and the filter cartridge is placed in the "dead space" between sink and wall. This filter is one of several new filtration devices using the Aquaspace compound filter media, which combines company developed and NASA technology. Aquaspace filters are used in industrial, commercial, residential, and recreational environments as well as by developing nations where water is highly contaminated.

1993-01-01

91

Filtering apparatus  

Science.gov (United States)

A vertical vessel having a lower inlet and an upper outlet enclosure separated by a main horizontal tube sheet. The inlet enclosure receives the flue gas from a boiler of a power system and the outlet enclosure supplies cleaned gas to the turbines. The inlet enclosure contains a plurality of particulate-removing clusters, each having a plurality of filter units. Each filter unit includes a filter clean-gas chamber defined by a plate and a perforated auxiliary tube sheet with filter tubes suspended from each tube sheet and a tube connected to each chamber for passing cleaned gas to the outlet enclosure. The clusters are suspended from the main tube sheet with their filter units extending vertically and the filter tubes passing through the tube sheet and opening in the outlet enclosure. The flue gas is circulated about the outside surfaces of the filter tubes and the particulate is absorbed in the pores of the filter tubes. Pulses to clean the filter tubes are passed through their inner holes through tubes free of bends which are aligned with the tubes that pass the clean gas.

Haldipur, Gaurang B. (Monroeville, PA); Dilmore, William J. (Murrysville, PA)

1992-01-01

92

Application of circular filter inserts  

International Nuclear Information System (INIS)

High efficiency particulate air (HEPA) filters are used in the ventilation of nuclear plant as passive clean-up devices. Traditionally, the work-horse of the industry has been the rectangular HEPA filter. An assessment of the problems associated with remote handling, changing, and disposal of these rectangular filters suggested that significant advantages to filtration systems could be obtained by the adoption of HEPA filters with circular geometry for both new and existing ventilation plants. This paper covers the development of circular geometry filters and highlights the advantages of this design over their rectangular counterparts. The work has resulted in a range of commercially available filters for flows from 45 m3/h up to 3400 m3/h. This paper also covers the development of a range of sizes and types of housings that employ simple change techniques which take advantage of the circular geometry. The systems considered here have been designed in response to the requirements for shielded (remote filter change) and for unshielded facilities (potentially for bag changing of filters). Additionally the designs have allowed for the possibility of retrofitting circular geometry HEPA filters in place of the rectangular geometry filter

93

Survey on Spam Filtering Techniques  

Directory of Open Access Journals (Sweden)

Full Text Available In the recent years spam became as a big problem of Internet and electronic communication. There developed a lot of techniques to fight them. In this paper the overview of existing e-mail spam filtering methods is given. The classification, evaluation, and comparison of traditional and learning-based methods are provided. Some personal anti-spam products are tested and compared. The statement for new approach in spam filtering technique is considered.

Saadat Nazirova

2011-08-01

94

Filtering Light  

Science.gov (United States)

Students learn how CCD cameras use color filters to create astronomical images in this Moveable Museum unit. The four-page PDF guide includes suggested general background readings for educators, activity notes, and step-by-step directions. Students look at black-and-white photos to understand gray scale and construct simple red and green cellophane filters and observe magazine images through them.

95

Filter apparatus  

International Nuclear Information System (INIS)

This invention relates to liquid filters, precoated by replaceable powders, which are used in the production of ultra pure water required for steam generation of electricity. The filter elements are capable of being installed and removed by remote control so that they can be used in nuclear power reactors. (UK)

96

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)

97

???????????? Optimization of the Particle Filter Algorithm  

Directory of Open Access Journals (Sweden)

Full Text Available ????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????In this paper, two problems were explicated by the detailed presentation of basic concepts and prin- ciples of the particle filter algorithm. One is particle impoverishment which dues to re-sampling, and another is particle degeneracy. To overcome these problems, existed methods of particle filter optimization are analy- zed. Finally, this paper presented a method that combine particle filter with intelligent algorithm, the combi- nation algorithm can overcome the shortcomings of particle filter effectively. Simulation results show that it is superior to the traditional particle filter optimization algorithm.

???

2011-12-01

98

Filter element  

International Nuclear Information System (INIS)

A tubular, inward-flow filter element is designed for use with a precoat layer and comprises a porous pleated filter medium, a lower end cap and outlet. Around the end cap is a flow straightener, which may comprise a stack of mesh discs or a wire knit mesh wrapping and serves to shield the filter medium from the flow through housing inlet. Enclosing the filter medium is a flow distributor comprising a helical winding of impervious tape. The lower windings touch one another, so that fluid reaches the lower end of medium mainly through the flow straightener, while the windings are progressively spaced further apart upwards to determine the flow to different parts of the medium. A uniform precoat layer is thus achieved. (author)

99

Emission computerized axial tomography from multiple gamma-camera views using frequency filtering.  

Science.gov (United States)

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. PMID:6966572

Pelletier, J L; Milan, C; Touzery, C; Coitoux, P; Gailliard, P; Budinger, T F

1980-01-01

100

Ethernet filter  

Energy Technology Data Exchange (ETDEWEB)

This invention is comprised of an apparatus and method that prevents access to unauthorized data in a local area network, such as Ethernet, in which information is transmitted from a transceiver to at least one workstation. Encoded data packets transmitted from the transceiver are filtered by splitting the packet into two signals. One signal contains the data that was transmitted, while the other signal contains tainted data. The filter determines whether a workstation is authorized to access the data, and then delivers either the tainted data to unauthorized workstations, or the data that was transmitted to authorized workstations.

Charney, E.J.; Tanzella, A.J.; Wujcik, J.G.

1990-11-09

 
 
 
 
101

Water Filters  

Science.gov (United States)

Seeking to find a more effective method of filtering potable water that was highly contaminated, Mike Pedersen, founder of Western Water International, learned that NASA had conducted extensive research in methods of purifying water on board manned spacecraft. The key is Aquaspace Compound, a proprietary WWI formula that scientifically blends various types of glandular activated charcoal with other active and inert ingredients. Aquaspace systems remove some substances; chlorine, by atomic adsorption, other types of organic chemicals by mechanical filtration and still others by catalytic reaction. Aquaspace filters are finding wide acceptance in industrial, commercial, residential and recreational applications in the U.S. and abroad.

1988-01-01

102

Christiansen filter realized by an odd smooth cylindrical lens.  

Science.gov (United States)

The Christiansen filter that is realized by odd smooth cylindrical lenses is analyzed in detail. Several popular filtering functions are discussed. The corresponding lens profile functions are obtained by an inverse scattering theory, which enables the filter to synthesize a desired prescribed response function. This kind of Christiansen filter has a passband narrower than that of the traditional Christiansen filter. Three Christiansen filters centered at 545 nm with full width at half-maximum of 2 nm are synthesized, and the approach to a better suppression of halos from the main transmission peak of the filters is presented in a systematic way. PMID:20035309

Li, Jian; Goddard, N; Xie, Kang

2010-01-01

103

Drug Filtering  

Science.gov (United States)

In this math meets health science activity, learners observe a model of exponential decay, and how kidneys filter blood. Learners will calculate the amount of a drug in the body over a period of time. Then, they will make and analyze the graphical representation of this exponential function. This lesson guide includes questions for learners, assessment options, extensions, and reflection questions.

Iles, Lawrence F.

2010-01-01

104

Nuclear filters  

International Nuclear Information System (INIS)

General problems pertaining to production and usage of millipore or nuclear filters are presented. Production of nuclear filter pores is based on different rates of etching of an initial polymer and its parts which have been subjected to radiation destruction under the action of accelerated heavy ions. Basing on the results of experiments carried out on a heavy ion cyclotron, a conclusion has been drawn that the most suitable for irradiation of films are xenon ions (Xe9+) with an energy of 150 MeV having a value of dE/dx=80 MeV/mg/cm2, and also ions MeV/mg/cm2 of argon Ar6+. As an irradiated polymer material use was of lavsan (dacron). For water the filter capacity constituted 1 m3/m2xh at the pore diameter d=0.1 ?m, and 100m3/m2xh at d=1 ?m. For air the capacity proved to be 200-300 times higher. Wide possibilities of application of nuclear filters for, primarily, the processes of fine refinement, separation and concentration of various products, both liquid and gaseous, are shown

105

Filters effects for different objects surfaces in reflective tomography laser radar  

Science.gov (United States)

In range-resolved reflective tomography laser radar imaging system, different objects surfaces have a major impact on signals reflected, and the corresponding different filters in filtered back-projection algorithm would attenuate varying degree artifacts in the resulting images reconstructed. In this paper, light reflection from a surface is described by the Stanford-Robertson bidirectional reflectance distribution function (SR BRDF) model developed by the Air Force. Different reflective parameters in SR BRDF were assumed to simulate various surfaces with different proportion between diffuse reflection and specular reflection. The projections of objects were simulated with 1 degree view increment covering the entire angular domain. We also add the experimental imaging results to validate the effectiveness of this SR BRDF model in reflection tomography. Several filters with different parameters were applied and the quality of images reconstruction was compared, especially beam hardening artifacts and the crossed streak artifacts.

Jin, Xiaofeng; Sun, Jianfeng; Yan, Yi; Zhou, Yu; Liu, Liren

2010-08-01

106

Plasmonic filters.  

Energy Technology Data Exchange (ETDEWEB)

Metal films perforated with subwavelength hole arrays have been show to demonstrate an effect known as Extraordinary Transmission (EOT). In EOT devices, optical transmission passbands arise that can have up to 90% transmission and a bandwidth that is only a few percent of the designed center wavelength. By placing a tunable dielectric in proximity to the EOT mesh, one can tune the center frequency of the passband. We have demonstrated over 1 micron of passive tuning in structures designed for an 11 micron center wavelength. If a suitable midwave (3-5 micron) tunable dielectric (perhaps BaTiO{sub 3}) were integrated with an EOT mesh designed for midwave operation, it is possible that a fast, voltage tunable, low temperature filter solution could be demonstrated with a several hundred nanometer passband. Such an element could, for example, replace certain components in a filter wheel solution.

Passmore, Brandon Scott; Shaner, Eric Arthur; Barrick, Todd A.

2009-09-01

107

Water Filter  

Science.gov (United States)

A compact, lightweight electrolytic water sterilizer available through Ambassador Marketing, generates silver ions in concentrations of 50 to 100 parts per billion in water flow system. The silver ions serve as an effective bactericide/deodorizer. Tap water passes through filtering element of silver that has been chemically plated onto activated carbon. The silver inhibits bacterial growth and the activated carbon removes objectionable tastes and odors caused by addition of chlorine and other chemicals in municipal water supply. The three models available are a kitchen unit, a "Tourister" unit for portable use while traveling and a refrigerator unit that attaches to the ice cube water line. A filter will treat 5,000 to 10,000 gallons of water.

1982-01-01

108

Autofluorescence removal using a customized filter set.  

Science.gov (United States)

Quantitative fluorescence microscopy is severely hindered by intrinsic autofluorescence (AF). Endogenous fluorescent molecules in tissue and cell samples emit fluorescence that often dominates signals from specific dyes. This makes AF removal critical to the development and practice of quantitative fluorescence microscopy. In this study, we showed that AF signal could be separated from specific signal using a customized filter set. The filter set used the same excitation and beam splitter as the standard filter set, but the emission filter was red-shifted 40-60 nm from the peak of the specific dye. This filter set configuration collected mostly AF with minimum contribution from the specific dye. A linear transformation of AF images was required to correct for the difference in exposure and filter configuration. The constants (slope and intercept) in linear transformation were obtained through a pixel to pixel comparison between AF images (no staining) obtained by the standard filter set and the customized AF filter set. After staining of specific dye, the standard filter collecting target dye spectra was used to capture both target signal and AF, whereas customized filter was used to capture only AF. AF removal was accomplished by subtracting the linear transformed AF image from the image obtained from the standard filter. To validate our approach, we examined weak staining of androgen receptor in an AF abundant prostate tissue sample. Our method revealed a similar but cleaner nuclear staining of androgen receptor in a specimen, when compared to a traditional autofluorescence removal method. PMID:23857594

Pang, Zhengyu; Barash, Eugene; Santamaria-Pang, Alberto; Sevinsky, Christopher; Li, Qing; Ginty, Fiona

2013-10-01

109

Gadamers verständnis der tradition  

Directory of Open Access Journals (Sweden)

Full Text Available (nema?ki In diesem Aufsatz man Gadamers Verständnis der wichtigen hermeneutischen Begriffe des Vorurteils, der Autorität und der Tradition erörtet. Der Vollzug des Verstehens, in dem die Vorurteile unvermeidlich sind, wird als Prozeß ihre ununterbrechende Korrektion bestimmt. Die positive Auswertung des begrifflichen Paar Autorität-Tradition ist ein karakteristischen Motiv der philosophischen Hermeneutik, für die die Autorität kein negativen Mitklang hat, sondern auf freie und rationelle Annahmung begründet ist. Der Zusammenhang des Verstehens und der Tradition ist eine dynamische Beziehung, in die weder Tradition noch das Subjekt des Verstehens ungeändert bleiben. Daraus führt man zwei Implikationen aus: daß der Sinn eines Textes kann man nie ausschöpfen, und seines Verstehen ein unendlichen Prozeß ist; und daß die Suspension der Vorurteilen nur gelingt, wo die Tradition sie sozusagen 'filtriert'. Der Author stellt eine Spannung aus, zwischen Gadamers Verständnis der hermeneutischen Produktivität der Tradition und des zeitlichen Abstand als Instanz die dem Verstehen beiträgt.

Radoj?i? Saša

2009-01-01

110

Ceramic filters  

Energy Technology Data Exchange (ETDEWEB)

Filters were formed from ceramic fibers, organic fibers, and a ceramic bond phase using a papermaking technique. The distribution of particulate ceramic bond phase was determined using a model silicon carbide system. As the ceramic fiber increased in length and diameter the distance between particles decreased. The calculated number of particles per area showed good agreement with the observed value. After firing, the papers were characterized using a biaxial load test. The strength of papers was proportional to the amount of bond phase included in the paper. All samples exhibited strain-tolerant behavior.

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

1995-12-31

111

Traditional Urban Aboriginal Religion  

Directory of Open Access Journals (Sweden)

Full Text Available This paper represents a group of Aboriginal people who claim traditionalAboriginal ownership of a large Australian metropolis. They have struggled for at least thelast 25 to 30 years to articulate and represent their contemporary group identity to the widerAustralian society that very often does not take their expressions seriously. This is largelybecause dominant discourses claim that ‘authentic’ Aboriginal culture only exists inremote, pristine areas far away from western society and that urban Aboriginal traditions,especially urban religious traditions are, today, defunct. This paper is an account of oneoccasion on which such traditional Aboriginal religious practice was performed before theeyes of a group of tourists.

Kristina Everett

2009-01-01

112

Improved Hessian multiscale enhancement filter.  

Science.gov (United States)

Traditional Hessian multiscale filter consider only the local geometric feature but not the global grayscale information. In medical image analysis, Hessian filter is usually used to enhance the blood vessels. However, it also produces some pseudo vascular structures or some isolate noise points, such as the nasal soft tissues that have the similar shape with the vessels in MRA data, which will increase the difficulty of cerebrovascular segmentation. To resolve this issue, an improved Hessian multiscale filter is proposed in this paper. An image grayscale factor is added to the vascular similarity function computed by Hessian matrix eigenvalue. This method is experimented on brain MRA data and lung CTA data. Experimental results show that this method can enhance vascular structures, and simultaneously reduce the appearance of the pseudo vascular structures and the isolated noise points. PMID:25227036

Yang, Jinzhu; Ma, Shuang; Sun, Qi; Tan, Wenjun; Xu, Mengjia; Chen, Nan; Zhao, Dazhe

2014-01-01

113

Filtering Water  

Science.gov (United States)

The first site related to water filtration is from the US Environmental Agency entitled EPA Environmental Education: Water Filtration (1 ). The two-page document explains the need for water filtration and the steps water treatment plants take to purify water. To further understand the process, a demonstration project is provided that illustrates these purification steps, which include coagulation, sedimentation, filtration, and disinfection. The second site is an interesting Flash animation called Filtration: How Does it Work (2 ) provided by Canada's Prairie Farm Rehabilitation Administration. Visitors will learn various types of filtration procedures and systems and the materials that are used such as carbon and sand. Next, from the National Science Foundation is a learning activity called Get Out the Gunk (3 ). Using just a few simple items from around the house, kids will be able to answer questions like "Does a filter work better with a lot of water rushing through, or a small trickle?" and "Does it make the water cleaner if you pour it through a filter twice?" The fourth Web site, Rapid Sand Filtration (4 ), is provided by Dottie Schmitt and Christie Shinault of Virginia Tech. The authors describe the process, which involves the flow of water through a bed of granular media, normally following settling basins in conventional water treatment trains to remove any particulate matter left over after flocculation and settling. Along with its thorough description, readers can view illustrations and photographs that further explain the process. The Vegetative Buffer Strips for Improved Surface Water Quality (5) Web site is provided by the Iowa State University Extension office. The document explains what vegetative buffer strips are, how they filter contaminants and sediment from surface water, how effective they are, and more. The sixth offering is a file called Infiltration Basins and Trenches (6) that is offered by the University of Wisconsin Extension. These structures are intended to collect water, have it infiltrate into the ground, and have it purified along the way. This document explains how effective they are at removing pollutants, how to install them, design guidelines, maintenance, and more. Next, from a site called Wilderness Survial.net is the Water Filtration Devices (7) page. Visitors read how to make a filtering system out of cloth, sand, crushed rock, charcoal, or a hollow log, although as is stated, the water still has to be purified. The last site, from the US Geological Survey, is called A Visit to a Wastewater-Treatment Plant: Primary Treatment of Wastewater (8). Although geared towards children, the site does a good job of explaining what happens at each stage of the treatment process and how pollutants are removed to help keep water clean. Everything from screening, pumping, aerating, sludge and scum removal, killing bacteria, and what is done with wastewater residuals is covered.

Brieske, Joel A.

2003-01-01

114

SAW Filter Performance Improvement  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

Dave, Monali R.

2012-01-01

115

Filter systems for IGCC applications  

Energy Technology Data Exchange (ETDEWEB)

The objectives of this program were to identify metallic filter medium to be utilized in the Integrated Gasification Combined Cycle process (IGCC). In IGCC processes utilizing high efficiency desulfurizing technology, the traditional corrosion attack, sulfidation, is minimized so that metallic filters are viable alternatives over ceramic filters. Tampa Electric Company`s Polk Power Station is being developed to demonstrate Integrated Gasification Combined Cycle technology. The Pall Gas Solid Separation (GSS) System is a self cleaning filtration system designed to remove virtually all particulate matter from gas streams. The heart of the system is the filter medium used to collect the particles on the filter surface. The medium`s filtration efficiency, uniformity, permeability, voids volume, and surface characteristics are all important to establishing a permeable permanent cake. In-house laboratory blowback tests, using representative full scale system particulate, were used to confirm the medium selection for this project. Test elements constructed from six alloys were supplied for exposure tests: PSS 310SC (modified 310S alloy); PSS 310SC heat treated; PSS 310SC-high Cr; PSS 310SC-high Cr heat treated; PSS Hastelloy X; and PSS Hastelloy X heat treated.

Bevan, S.; Gieger, R.; Sobel, N.; Johnson, D.

1995-11-01

116

The "Natural Law Tradition."  

Science.gov (United States)

A discussion of natural law outlines some of the theory and tradition surrounding it and examines its relationship to the social science and legal curriculum and to the teaching of jurisprudence. (MSE)

Finnis, John

1986-01-01

117

Traditional Cumberland Sausage  

Address Food Policy Unit, Regional and Local Food Team. Area 7e, 9 Millbank ... \\The ingredients for Traditional Cumberland sausages consists of: • boneless ... \\from natural pig intestines which are larger than lamb intestines hence creating a\\ ...

118

The Fine Dutch Tradition:  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Publication of the exhibition and symposium on water adaptive urban planning and architecture in Bangkok. The Urban Fine Dutch Tradition is a dynamic tradition of making urban designs using the parameters of the natural system – incorperating in an efficient way the hydrological cycle, the soil and subsurface conditions, technology and urban development opportunities. Sustainability is the capacity of making a sensible choice for enabling technology taking a perspective from the natural...

Hooimeijer, F. L.

2013-01-01

119

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

120

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)

 
 
 
 
121

Sensor Fusion with Square-Root Cubature Information Filtering  

Directory of Open Access Journals (Sweden)

Full Text Available This paper derives a square-root information-type filtering algorithm for nonlinear multi-sensor fusion problems using the cubature Kalman filter theory. The resulting filter is called the square-root cubature Information filter (SCIF. The SCIF propagates the square-root information matrices derived from numerically stable matrix operations and is therefore numerically robust. The SCIF is applied to a highly maneuvering target tracking problem in a distributed sensor network with feedback. The SCIF’s performance is finally compared with the regular cubature information filter and the traditional extended information filter. The results, presented herein, indicate that the SCIF is the most reliable of all three filters and yields a more accurate estimate than the extended information filter.

Ienkaran Arasaratnam

2013-02-01

122

Child Psychotherapy: Converging Traditions  

Science.gov (United States)

In this paper I outline some of the ways in which I believe the psychoanalytic traditions in North America and in Great Britain are influencing each other. I identify points of convergence and divergence at this moment in the evolution of psychoanalytic theory and technique. I then point out some of the implications of relational perspectives in…

Altman, Neil

2004-01-01

123

Traditional Farmfresh Turkey - TSG  

Traditional Farmfresh production methods result in turkeys with a high meat to \\weight ratio ... colour and finish, and a full fat cover visible under the skin. 3.6 \\Description of ... Protein included in the diet must be only vegetable or fish. • \\From 10 ...

124

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

125

Making Tradition Healthy  

Centers for Disease Control (CDC) Podcasts

In this podcast, a Latina nutrition educator shows how a community worked with local farmers to grow produce traditionally enjoyed by Hispanic/Latinos.  Created: 11/1/2007 by National Diabetes Education Program (NDEP), a joint program of the Centers for Disease Control and Prevention and the National Institutes of Health.   Date Released: 11/10/2007.

2007-11-01

126

Multichannel image filter based on FNN  

Science.gov (United States)

A new filter for the multichannel image based on the technology of Fuzzy Neural Network (FNN) is proposed. Multichannel images obtained by remote imaging technology are often corrupted by noises such as gauss noise, impulse noise and speckle noise. Tradition linear filters and some nonlinear filters can't fulfill the task of removing the mixed noises clearly and quickly. The biology vision systems are sense to wide bind of light and their network structure can perform in parallel manner and filter mixed noises, which inspires to the design of FNN image filter. The neural network structure in the presented filter is good at learning from sample data and parallel calculating while the fuzzy mechanism embedded in the network can detect different patterns in order to remove noise and keep details and textures. The filter has three function layers. In the first layer, corrupted image is introduced into five fuzzy sets characterized by membership functions. In the middle layer, fuzzy reasoning hidden in the neural network detects the data pattern and indicated noise pixels. In the output layer, the defuzifieation process is done and the restored image is obtained. A learning method based on the advanced genetic algorithm is adopted to adjust the network parameters from a set of training data. Experimental results shows that the FNN filter is effective in noise canceling and simple to be realized by hardware.

Liu, Zhongren; Sun, Sheng-He

2001-09-01

127

Traditional Medicine in Zimbabwe  

Directory of Open Access Journals (Sweden)

Full Text Available This study was carried out to help demystify traditional medical practices in Zimbabwe and assist people in understanding Zimbabwean traditional medicine. The Zimbabwean traditional religion involves a hierarchy of spirit mediums differing in the way they practice traditional medicine, as well as the origin and power of the spirit(s that possess(es them. MaGombwe, mediums of angels of God, occupy the highest level on the hierarchy. The second level is that of maSadunhu, the spirit mediums of the original leaders of clans who look after the interests of members of their clans. The third level is that of maTateguru, the spirits who look after the interests of the families they left behind. These spirits of great grandparents are complimented by spirits of grandparents who possess their mediums only to get a specific thing done and then disappear. The fourth level is occupied by N’angas, the ‘real traditional medical practitioners.’ These mediums may be possessed by spirits from any of the above levels, and differ from mediums at the original level in that they charge clients and the powers of their spirits are lower. The spirits at any of the levels are complimented by maShave, spirits that were created to perform specific tasks. The role of the spirit mediums is to service spiritual and medicinal interests of people. Training at the different levels of spirit mediums involves rigorous and tedious apprenticeship systems, and the mediums are willing to cooperate with other service providers if certain conditions are met.

Takawira Kazembe

2007-06-01

128

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

129

Piecewise Constant Sequential Importance Sampling for Fast Particle Filtering  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Particle filters are key algorithms for object tracking under non-linear, non-Gaussian dynamics. The high computational cost of particle filters, however, hampers their applicability in cases where the likelihood model is costly to evaluate, or where large numbers of particles are required to represent the posterior. We introduce the approximate sequential importance sampling/resampling (ASIR) algorithm, which aims at reducing the cost of traditional particle filters by appr...

Demirel, O?mer; Smal, Ihor; Niessen, Wiro J.; Meijering, Erik; Sbalzarini, Ivo F.

2013-01-01

130

Research of Collaborative Filtering Recommendation Algorithm based on Network Structure  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper combines the classic collaborative filtering algorithm with personalized recommendation algorithm based on network structure. For the data sparsity and malicious behavior problems of traditional collaborative filtering algorithm, the paper introduces a new kind of social network-based collaborative filtering algorithm. In order to improve the accuracy of the personalized recommendation technology, we first define empty state in the state space of multi-dimensional semi-Markov proce...

Peng, Hui

2013-01-01

131

Filtering, FDR and power  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

van Iterson Maarten; Boer Judith M; de Menezes Renée X

2010-01-01

132

Mica nuclear track filters  

International Nuclear Information System (INIS)

Mica nuclear track filters are produced by irradiation of mica with energetic heavy ions and subsequent etching. The properties of these filters and the air through-put up to 3000C are reviewed. At an industrial plant mica filters are used to filter 0C hot waste gas containing radioactive aerosols from the production of reactor fuel elements. After filtration the aerosol particles on the filters are examined by different methods for their properties. (orig.)

133

Spam filter analysis  

CERN Document Server

Unsolicited bulk email (aka. spam) is a major problem on the Internet. To counter spam, several techniques, ranging from spam filters to mail protocol extensions like hashcash, have been proposed. In this paper we investigate the effectiveness of several spam filtering techniques and technologies. Our analysis was performed by simulating email traffic under different conditions. We show that genetic algorithm based spam filters perform best at server level and naive Bayesian filters are the most appropriate for filtering at user level.

Garcia, F D; Basiuk, Vincent; Becoulet, Alain; Coulon, Jean-Pierre; Garcia, Flavio D.; Hoepman, Jaap-Henk; Hutter, Thierry; Saoutic, Vincent

2004-01-01

134

Optimization of filter loading  

International Nuclear Information System (INIS)

The introduction of 10 CFR Part 61 has created potential difficulties in the disposal of spent cartridge filters. When this report was prepared, Rancho Seco had no method of packaging and disposing of class B or C filters. This work examined methods to minimize the total operating cost of cartridge filters while maintaining them below the class A limit. It was found that by encapsulating filters in cement the filter operating costs could be minimized

135

The Hausa Lexicographic Tradition  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 accor...

Roxana Ma Newman; Paul Newman

2011-01-01

136

Robot Visual Servo with Fuzzy Particle Filter  

Directory of Open Access Journals (Sweden)

Full Text Available This paper proposes a robot visual servo method with an adaptive particle filter based on fuzzy logic theory to online estimate the total Jacobian matrix of a robot visual servo system. A set of fuzzy rules are used to select appropriate numbers of particles according to the filtering estimation errors. When an estimation error is high more particles are used, and when the estimation error is low fewer particles are used. The visual servo results on a two degree-of-freedom robot system show that the proposed fuzzy adaptive particle filter visual servo method needs less time than that of traditional particle filter visual servo method to get a comparative tracking accuracy.

Jie Ma

2012-04-01

137

IMPLEMENTATION OF DIGITAL FILTERS FOR HIGH THROUGHPUT APPLICATIONS ON FPGA  

Directory of Open Access Journals (Sweden)

Full Text Available The digital filter implementation in FPGA,utilising the dedicated hardware resources can effectively achieve ASIC-like performance while reducing development time cost and risks. Advantage of FPGA approach to digital filter implementation including sampling rates than are availablefrom traditional DSP chips. In this paper a low pass,band pass and highpass FIR filter is implemented on FPGA.This approach gives a better performance than the common filter structures in terms of speed of operation,cost and power consumption in real time.In this technique, codes for direct fixed point FIR filter have been realized. Modules such as multiplier, adder, ram and two’s complement were used. For an N order filter the filter the number of registers and adders required is N and the number of multipliers required is N+1.For high speed and high throughput applications,MAC is used and that consumes less power.

T.PUSHPA

2013-04-01

138

Rigid porous filter  

Science.gov (United States)

The present invention involves a porous rigid filter including a plurality of concentric filtration elements having internal flow passages and forming external flow passages there between. The present invention also involves a pressure vessel containing the filter for the removal of particulates from high pressure particulate containing gases, and further involves a method for using the filter to remove such particulates. The present filter has the advantage of requiring fewer filter elements due to the high surface area-to-volume ratio provided by the filter, requires a reduced pressure vessel size, and exhibits enhanced mechanical design properties, improved cleaning properties, configuration options, modularity and ease of fabrication.

Chiang, Ta-Kuan (Morgantown, WV); Straub, Douglas L. (Morgantown, WV); Dennis, Richard A. (Morgantown, WV)

2000-01-01

139

Optimal Filter Systems for Photometric Redshift Estimation  

Science.gov (United States)

In the coming years, several cosmological surveys will rely on imaging data to estimate the redshift of galaxies, using traditional filter systems with 4-5 optical broad bands; narrower filters improve the spectral resolution, but strongly reduce the total system throughput. We explore how photometric redshift performance depends on the number of filters nf , characterizing the survey depth by the fraction of galaxies with unambiguous redshift estimates. For a combination of total exposure time and telescope imaging area of 270 hr m2, 4-5 filter systems perform significantly worse, both in completeness depth and precision, than systems with nf gsim 8 filters. Our results suggest that for low nf the color-redshift degeneracies overwhelm the improvements in photometric depth, and that even at higher nf the effective photometric redshift depth decreases much more slowly with filter width than naively expected from the reduction in the signal-to-noise ratio. Adding near-IR observations improves the performance of low-nf systems, but still the system which maximizes the photometric redshift completeness is formed by nine filters with logarithmically increasing bandwidth (constant resolution) and half-band overlap, reaching ~0.7 mag deeper, with 10% better redshift precision, than 4-5 filter systems. A system with 20 constant-width, nonoverlapping filters reaches only ~0.1 mag shallower than 4-5 filter systems, but has a precision almost three times better, ?z = 0.014(1 + z) versus ?z = 0.042(1 + z). We briefly discuss a practical implementation of such a photometric system: the ALHAMBRA Survey.

Benítez, N.; Moles, M.; Aguerri, J. A. L.; Alfaro, E.; Broadhurst, T.; Cabrera-Caño, J.; Castander, F. J.; Cepa, J.; Cerviño, M.; Cristóbal-Hornillos, D.; Fernández-Soto, A.; González Delgado, R. M.; Infante, L.; Márquez, I.; Martínez, V. J.; Masegosa, J.; Del Olmo, A.; Perea, J.; Prada, F.; Quintana, J. M.; Sánchez, S. F.

2009-02-01

140

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

 
 
 
 
141

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

142

Cordierite silicon nitride filters  

Energy Technology Data Exchange (ETDEWEB)

The objective of this project was to develop a silicon nitride based crossflow filter. This report summarizes the findings and results of the project. The project was phased with Phase I consisting of filter material development and crossflow filter design. Phase II involved filter manufacturing, filter testing under simulated conditions and reporting the results. In Phase I, Cordierite Silicon Nitride (CSN) was developed and tested for permeability and strength. Target values for each of these parameters were established early in the program. The values were met by the material development effort in Phase I. The crossflow filter design effort proceeded by developing a macroscopic design based on required surface area and estimated stresses. Then the thermal and pressure stresses were estimated using finite element analysis. In Phase II of this program, the filter manufacturing technique was developed, and the manufactured filters were tested. The technique developed involved press-bonding extruded tiles to form a filter, producing a monolithic filter after sintering. Filters manufactured using this technique were tested at Acurex and at the Westinghouse Science and Technology Center. The filters did not delaminate during testing and operated and high collection efficiency and good cleanability. Further development in areas of sintering and filter design is recommended.

Sawyer, J.; Buchan, B. (Acurex Environmental Corp., Mountain View, CA (United States)); Duiven, R.; Berger, M. (Aerotherm Corp., Mountain View, CA (United States)); Cleveland, J.; Ferri, J. (GTE Products Corp., Towanda, PA (United States))

1992-02-01

143

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

144

Novel Backup Filter Device for Candle Filters  

Energy Technology Data Exchange (ETDEWEB)

The currently preferred means of particulate removal from process or combustion gas generated by advanced coal-based power production processes is filtration with candle filters. However, candle filters have not shown the requisite reliability to be commercially viable for hot gas clean up for either integrated gasifier combined cycle (IGCC) or pressurized fluid bed combustion (PFBC) processes. Even a single candle failure can lead to unacceptable ash breakthrough, which can result in (a) damage to highly sensitive and expensive downstream equipment, (b) unacceptably low system on-stream factor, and (c) unplanned outages. The U.S. Department of Energy (DOE) has recognized the need to have fail-safe devices installed within or downstream from candle filters. In addition to CeraMem, DOE has contracted with Siemens-Westinghouse, the Energy & Environmental Research Center (EERC) at the University of North Dakota, and the Southern Research Institute (SRI) to develop novel fail-safe devices. Siemens-Westinghouse is evaluating honeycomb-based filter devices on the clean-side of the candle filter that can operate up to 870 C. The EERC is developing a highly porous ceramic disk with a sticky yet temperature-stable coating that will trap dust in the event of filter failure. SRI is developing the Full-Flow Mechanical Safeguard Device that provides a positive seal for the candle filter. Operation of the SRI device is triggered by the higher-than-normal gas flow from a broken candle. The CeraMem approach is similar to that of Siemens-Westinghouse and involves the development of honeycomb-based filters that operate on the clean-side of a candle filter. The overall objective of this project is to fabricate and test silicon carbide-based honeycomb failsafe filters for protection of downstream equipment in advanced coal conversion processes. The fail-safe filter, installed directly downstream of a candle filter, should have the capability for stopping essentially all particulate bypassing a broken or leaking candle while having a low enough pressure drop to allow the candle to be backpulse-regenerated. Forward-flow pressure drop should increase by no more than 20% because of incorporation of the fail-safe filter.

Bishop, B.; Goldsmith, R.; Dunham, G.; Henderson, A.

2002-09-18

145

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

146

Earth Water Filter  

Science.gov (United States)

Designing a filter that turns black, salty, muck into drinkable water is a tall order. In this video segment, ZOOM cast members take cues from what they know about natural sediment filters, use similar materials to create their own water filters, and evaluate which combinations of materials make the fastest, most efficient filters. The segment is four minutes fifty-four seconds in length. A background essay and discussion questions are included.

147

HEPA filter encapsulation  

Science.gov (United States)

A low viscosity resin is delivered into a spent HEPA filter or other waste. The resin is introduced into the filter or other waste using a vacuum to assist in the mass transfer of the resin through the filter media or other waste.

Gates-Anderson, Dianne D. (Union City, CA); Kidd, Scott D. (Brentwood, CA); Bowers, John S. (Manteca, CA); Attebery, Ronald W. (San Lorenzo, CA)

2003-01-01

148

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

149

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

150

Guided image filtering.  

Science.gov (United States)

In this paper, we propose a novel explicit image filter called guided filter. Derived from a local linear model, the guided filter computes the filtering output by considering the content of a guidance image, which can be the input image itself or another different image. The guided filter can be used as an edge-preserving smoothing operator like the popular bilateral filter [1], but it has better behaviors near edges. The guided filter is also a more generic concept beyond smoothing: It can transfer the structures of the guidance image to the filtering output, enabling new filtering applications like dehazing and guided feathering. Moreover, the guided filter naturally has a fast and nonapproximate linear time algorithm, regardless of the kernel size and the intensity range. Currently, it is one of the fastest edge-preserving filters. Experiments show that the guided filter is both effective and efficient in a great variety of computer vision and computer graphics applications, including edge-aware smoothing, detail enhancement, HDR compression, image matting/feathering, dehazing, joint upsampling, etc. PMID:23599054

He, Kaiming; Sun, Jian; Tang, Xiaoou

2013-06-01

151

Practical Active Capacitor Filter  

Science.gov (United States)

A method and apparatus is described that filters an electrical signal. The filtering uses a capacitor multiplier circuit where the capacitor multiplier circuit uses at least one amplifier circuit and at least one capacitor. A filtered electrical signal results from a direct connection from an output of the at least one amplifier circuit.

Shuler, Robert L., Jr. (Inventor)

2005-01-01

152

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

153

Application of Moving Object Tracking Based on Kalman Filter Algorithm  

Directory of Open Access Journals (Sweden)

Full Text Available The moving object module matching method base on Kalman Filter (KF algorithm which proposed to solve the problem of traditional moving object matching method’s, that fault of huge searching range and weakness in real-time processing. Relative to traditional module matching method, the method mentioned here effectively improved the speed and the accuracy of object tracking. This method has tripled the object matching speed of traditional tracking method.

Xiao Zhansheng

2013-01-01

154

Research of EMCCD image filtering method based on noise detection and fuzzy adaptive median filter  

Science.gov (United States)

Traditional median filtering algorithm is mainly designed for stationary noise density, which realizes the image smooth but leads to edge fuzzy. The noise density of Electron Multiplying CCD (EMCCD) image varies with the gain. In this paper, a new noise detection and fuzzy adaptive median filter (NDFAMF) is proposed to overcome such drawbacks. First, the noise pixels in the center of the filter window were identified. Secondly, the thresholds were introduced for the detected "noise points". Based on the thresholds and median of the filtering window, the fuzzy membership function of noise points was put forward, using the fuzzy membership function to filter the noise points. Finally, according to the density of noise in the filtering window the filtering window can change the size adaptive. Simulation and experimental results show that the new algorithm is able to remove noise pixels effectively and protect the details well in the image. The performance is better than the other median filters under the condition of low noise density and relatively stable under the condition of high noise density.

Qi, Lei; Zhang, Wenwen; Chen, Qian; Gu, Guohua; Qian, Yuehong

2013-12-01

155

Non-traditional inheritance  

International Nuclear Information System (INIS)

In the last few years, several non-traditional forms of inheritance have been recognized. These include mosaicism, cytoplasmic inheritance, uniparental disomy, imprinting, amplification/anticipation, and somatic recombination. Genomic imprinting (GI) is the dependence of the phenotype on the sex of the transmitting parent. GI in humans seems to involve growth, behaviour, and survival in utero. The detailed mechanism of genomic imprinting is not known, but it seems that some process is involved in turning a gene off; this probably involves two genes, one of which produces a product that turns a gene off, and the gene that is itself turned off. The process of imprinting (turning off) may be associated with methylation. Erasure of imprinting can occur, and seems to be associated with meiosis. 10 refs

156

Wavelet transform adaptive filtering  

Science.gov (United States)

An LMS adaptive filtering algorithm is presented utilizing wavelet transforms. Its performance is compared to DCT and Walsh-Hadamard transform-based adaptive filtering. The experimental analysis is performed in the case of the system identification of an unknown system or filter for stationary input signals. The results show some improvement in the weight modelling of the filter with comparable convergence rates. A new performance criteria, the diagonality factor, is introduced in order to show the specific effect of the wavelet transform on a signal. A Mean Average Difference is also utilized to compare the weight modelling performance of the various transform-based LMS adaptive filterings studied in this paper.

Dang, Laurence M.

1994-10-01

157

Variable digital filters  

Science.gov (United States)

Different methods and practical experiences for the design and implementations of variable digital filters are presented with emphasis on the case of a selective filter with cutoff frequencies subject to change. It is shown that a combination of a coefficient calculator and a digital filter can overcome difficulties which arise if the allpass transformation is directly applied for the implementation. Higher flexibility is achieved when a microcomputer is used to design the filter for given specifications, and when its speed is sufficiently high to carry out the filtering operation in real-time afterwards.

Schuessler, H. W.; Kolb, H. J.

1982-06-01

158

Creating Filtered, Translated Newsfeeds  

Directory of Open Access Journals (Sweden)

Full Text Available Google Translate's API creates the possibility to leverage machine translation to both filter global newsfeeds for content regarding a specific topic, and to aggregate filtered feed items as a newsfeed. Filtered items can be translated so that the resulting newsfeed can provide basic information about topic-specific news articles from around the globe in the desired language of the consumer. This article explores a possible solution for inputting alternate words and phrases in the user’s native language, aggregating and filtering newsfeeds progammatically, managing filter terms, and using Google Translate’s API.

Linn Marks Collins

2010-06-01

159

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

160

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.)

 
 
 
 
161

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

162

Optimal filter systems for photometric redshift estimation  

CERN Document Server

In the next years, several cosmological surveys will rely on imaging data to estimate the redshift of galaxies, using traditional filter systems with 4-5 optical broad bands; narrower filters improve the spectral resolution, but strongly reduce the total system throughput. We explore how photometric redshift performance depends on the number of filters n_f, characterizing the survey depth through the fraction of galaxies with unambiguous redshift estimates. For a combination of total exposure time and telescope imaging area of 270 hrs m^2, 4-5 filter systems perform significantly worse, both in completeness depth and precision, than systems with n_f >= 8 filters. Our results suggest that for low n_f, the color-redshift degeneracies overwhelm the improvements in photometric depth, and that even at higher n_f, the effective photometric redshift depth decreases much more slowly with filter width than naively expected from the reduction in S/N. Adding near-IR observations improves the performance of low n_f syste...

Benítez, N; López-Aguerri, J A; Alfaro, E; Broadhurst, T; Cabrera, J; Castander, F J; Cepa, J; Cerviño, M; Cristobal-Hornillos, D; Fernández-Soto, A; González-Delgado, R M; Infante, L; Márquez, I; Martínez, V J; Masegosa, J; Del Olmo, A; Perea, J; Prada, F; Quintana, J M; Sánchez, S F

2008-01-01

163

Bias Reduction and Filter Convergence for Long Range Stereo  

Science.gov (United States)

We are concerned here with improving long range stereo by filtering image sequences. Traditionally, measurement errors from stereo camera systems have been approximated as 3-D Gaussians, where the mean is derived by triangulation and the covariance by linearized error propagation. However, there are two problems that arise when filtering such 3-D measurements. First, stereo triangulation suffers from a range dependent statistical bias; when filtering this leads to over-estimating the true range. Second, filtering 3-D measurements derived via linearized error propagation leads to apparent filter divergence; the estimator is biased to under-estimate range. To address the first issue, we examine the statistical behavior of stereo triangulation and show how to remove the bias by series expansion. The solution to the second problem is to filter with image coordinates as measurements instead of triangulated 3-D coordinates.

Sibley, Gabe; Matthies, Larry; Sukhatme, Gaurav

2005-01-01

164

Optimal Sharpening of Compensated Comb Decimation Filters: Analysis and Design  

Science.gov (United States)

Comb filters are a class of low-complexity filters especially useful for multistage decimation processes. However, the magnitude response of comb filters presents a droop in the passband region and low stopband attenuation, which is undesirable in many applications. In this work, it is shown that, for stringent magnitude specifications, sharpening compensated comb filters requires a lower-degree sharpening polynomial compared to sharpening comb filters without compensation, resulting in a solution with lower computational complexity. Using a simple three-addition compensator and an optimization-based derivation of sharpening polynomials, we introduce an effective low-complexity filtering scheme. Design examples are presented in order to show the performance improvement in terms of passband distortion and selectivity compared to other methods based on the traditional Kaiser-Hamming sharpening and the Chebyshev sharpening techniques recently introduced in the literature. PMID:24578674

Troncoso Romero, David Ernesto

2014-01-01

165

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

166

Symmetric Phase Only Filtering for Improved DPIV Data Processing  

Science.gov (United States)

The standard approach in Digital Particle Image Velocimetry (DPIV) data processing is to use Fast Fourier Transforms to obtain the cross-correlation of two single exposure subregions, where the location of the cross-correlation peak is representative of the most probable particle displacement across the subregion. This standard DPIV processing technique is analogous to Matched Spatial Filtering, a technique commonly used in optical correlators to perform the crosscorrelation operation. Phase only filtering is a well known variation of Matched Spatial Filtering, which when used to process DPIV image data yields correlation peaks which are narrower and up to an order of magnitude larger than those obtained using traditional DPIV processing. In addition to possessing desirable correlation plane features, phase only filters also provide superior performance in the presence of DC noise in the correlation subregion. When DPIV image subregions contaminated with surface flare light or high background noise levels are processed using phase only filters, the correlation peak pertaining only to the particle displacement is readily detected above any signal stemming from the DC objects. Tedious image masking or background image subtraction are not required. Both theoretical and experimental analyses of the signal-to-noise ratio performance of the filter functions are presented. In addition, a new Symmetric Phase Only Filtering (SPOF) technique, which is a variation on the traditional phase only filtering technique, is described and demonstrated. The SPOF technique exceeds the performance of the traditionally accepted phase only filtering techniques and is easily implemented in standard DPIV FFT based correlation processing with no significant computational performance penalty. An "Automatic" SPOF algorithm is presented which determines when the SPOF is able to provide better signal to noise results than traditional PIV processing. The SPOF based optical correlation processing approach is presented as a new paradigm for more robust cross-correlation processing of low signal-to-noise ratio DPIV image data."

Wernet, Mark P.

2006-01-01

167

Kalman filtering technique for reactivity measurement  

International Nuclear Information System (INIS)

Measurement of reactivity and its on-line display is of great help in calibration of reactivity control and safety devices and in the planning of suitable actions during the reactor operation. In traditional approaches the reactivity is estimated from reactor period or by solving the inverse point kinetic equation. In this paper, an entirely new approach based on the Kalman filtering technique has been presented. The theory and design of the reactivity measuring instrument based on the approach has been explained. Its performance has been compared with traditional approaches by estimation of transient reactivity from flux variation data recorded in a research reactor. It is demonstrated that the Kalman filtering approach is superior to other methods from the viewpoints of accuracy, noise suppression, and robustness against uncertainties in the reactor parameters. (author). 1 fig

168

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

169

Dual filtered backprojection for micro-rotation confocal microscopy  

International Nuclear Information System (INIS)

Micro-rotation confocal microscopy is a novel optical imaging technique which employs dielectric fields to trap and rotate individual cells to facilitate 3D fluorescence imaging using a confocal microscope. In contrast to computed tomography (CT) where an image can be modelled as parallel projection of an object, the ideal confocal image is recorded as a central slice of the object corresponding to the focal plane. In CT, the projection images and the 3D object are related by the Fourier slice theorem which states that the Fourier transform of a CT image is equal to the central slice of the Fourier transform of the 3D object. In the micro-rotation application, we have a dual form of this setting, i.e. the Fourier transform of the confocal image equals the parallel projection of the Fourier transform of the 3D object. Based on the observed duality, we present here the dual of the classical filtered back projection (FBP) algorithm and apply it in micro-rotation confocal imaging. Our experiments on real data demonstrate that the proposed method is a fast and reliable algorithm for the micro-rotation application, as FBP is for CT application

170

Dual filtered backprojection for micro-rotation confocal microscopy  

Science.gov (United States)

Micro-rotation confocal microscopy is a novel optical imaging technique which employs dielectric fields to trap and rotate individual cells to facilitate 3D fluorescence imaging using a confocal microscope. In contrast to computed tomography (CT) where an image can be modelled as parallel projection of an object, the ideal confocal image is recorded as a central slice of the object corresponding to the focal plane. In CT, the projection images and the 3D object are related by the Fourier slice theorem which states that the Fourier transform of a CT image is equal to the central slice of the Fourier transform of the 3D object. In the micro-rotation application, we have a dual form of this setting, i.e. the Fourier transform of the confocal image equals the parallel projection of the Fourier transform of the 3D object. Based on the observed duality, we present here the dual of the classical filtered back projection (FBP) algorithm and apply it in micro-rotation confocal imaging. Our experiments on real data demonstrate that the proposed method is a fast and reliable algorithm for the micro-rotation application, as FBP is for CT application.

Laksameethanasan, Danai; Brandt, Sami S.; Renaud, Olivier; Shorte, Spencer L.

2009-01-01

171

Sensory Pollution from Bag Filters, Carbon Filters and Combinations  

DEFF Research Database (Denmark)

Used ventilation filters are a major source of sensory pollutants in air handling systems. The objective of the present study was to evaluate the net effect that different combinations of filters had on perceived air quality after 5 months of continuous filtration of outdoor suburban air. A panel of 32 subjects assessed different sets of used filters and identical sets consisting of new filters. Additionally, filter weights and pressure drops were measured at the beginning and end of the operation period. The filter sets included single EU5 and EU7 fiberglass filters, an EU7 filter protected by an upstream pre-filter (changed monthly), an EU7 filter protected by an upstream activated carbon (AC) filter, and EU7 filters with an AC filter either downstream or both upstream and downstream. In addition, two types of stand-alone combination filters were evaluated: a bag-type fiberglass filter that contained AC and a synthetic fiber cartridge filter that contained AC. Air that had passed through used filters was most acceptable for those sets in which an AC filter was used downstream of the particle filter. Comparable air quality was achieved with the stand-alone bag filter that contained AC. Furthermore, its pressure drop changed very little during the 5 months of service, and it had the added benefit of removing a large fraction of ozone from the airstream. If similar results are obtained over a wider variety of soiling conditions, such filters may be a viable solution to a long recognized problem.

Bekö, Gabriel; Clausen, Geo

2008-01-01

172

Interdigital cavity filter design  

International Nuclear Information System (INIS)

The lower hybrid current drive system will be interferenced by jamming signal in the EAST experiment site, so a interdigital cavity filter with passband centered at 2.45 GHz is designed to repress the jamming signal. This paper gives the particular description of a theoretical analysis and practical design for interdigital cavity filter, and the filter is simulated by HFSS-software which greatly improves the efficiency and accuracy of the design. (authors)

173

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

174

Morphing Ensemble Kalman Filters  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

175

Linear phase compressive filter  

Science.gov (United States)

A phase linear filter for soliton suppression is in the form of a laddered series of stages of non-commensurate low pass filters with each low pass filter having a series coupled inductance (L) and a reverse biased, voltage dependent varactor diode, to ground which acts as a variable capacitance (C). L and C values are set to levels which correspond to a linear or conventional phase linear filter. Inductance is mapped directly from that of an equivalent nonlinear transmission line and capacitance is mapped from the linear case using a large signal equivalent of a nonlinear transmission line.

McEwan, Thomas E. (Livermore, CA)

1995-01-01

176

Backflushable filter insert  

International Nuclear Information System (INIS)

Filter elements are mounted on a tube plate beneath an accumulator chamber whose wall is extended by skirt and flange to form a closure for the top of pressure vessel. The accumulator chamber is annular around a central pipe which serves as the outlet for filtered water passing from the filter elements. The chamber contains filtered compressed air from supply. Periodically the filtration of water is stopped and vessel is drained. Then a valve is opened, allowing the accumulated air to flow from chamber up a pipe and down pipe, pushing the filtered water from pipe back through the filter elements to clean them. The accumulator chamber is so proportioned, relative to the volume of the system communicating therewith during backflushing, that the equilibrium pressure during backflushing cannot exceed the pressure rating of the vessel. However a line monitors the pressure at the top of the vessel, and if it rises too far a bleed valve is automatically opened to depressurise the system. The chamber is intended to replace the lid of an existing vessel to convert a filter using filter aid to one using permanent filter elements. (author)

177

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

178

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

179

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

180

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

 
 
 
 
181

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

182

Filter Design: Analysis and Review  

Directory of Open Access Journals (Sweden)

Full Text Available This paper represents the review analysis of various types of filters design. In this paper we discuss the designing of filters. For discussing the designing of filters we consider the some standard paper which is based on filter design. First we will discuss about filter then we will discuss about types of filter and give the review on different ways of designing of filter.

Anirudh Singhal

2014-01-01

183

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

184

Traditional West Coast Native Medicine  

Science.gov (United States)

An important part of the complex culture of the Native people of Canada's Pacific coast is the traditional system of medicine each culture has developed. Population loss from epidemics and the influence of dominant European cultures has resulted in loss of many aspects of traditional medicine. Although some Native practices are potentially hazardous, continuation of traditional approaches to illness remains an important part of health care for many Native people. The use of “devil's club” plant by the Haida people illustrates that Native medicine has both spiritual and physical properties. Modern family practice shares many important foundations with traditional healing systems. PMID:21253031

Deagle, George

1988-01-01

185

Reception of the Istrian musical tradition(s)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The successive colonization of Istria with culturally differentiated populations, and peripheral position of the peninsula regarding both the Latin and Slav worlds, has conditioned interesting phenomena which defines the traditional life of the province. On the spiritual level it is primarily reflected in two cultural dimensions: the language and traditional music.

Maruši? Dario

2007-01-01

186

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

187

Balleans and filters  

Directory of Open Access Journals (Sweden)

Full Text Available A ballean (equivalently, a coarse structure is an asymptotic counterpart of a uniform topo- logical space.We introduce three new constructions (namely, a ballean-filter mix, a ballean-ideal mix and a filter product of directed sets to give some balleans with extremal properties. In particular, we construct a non-metrizable Frechet group ballean.

O. V. Petrenko

2012-07-01

188

Filter cake breaker systems  

Energy Technology Data Exchange (ETDEWEB)

Drilling fluids filter cakes are based on a combination of properly graded dispersed particles and polysaccharide polymers. High efficiency filter cakes are formed by these combination , and their formation on wellbore walls during the drilling process has, among other roles, the task of protecting the formation from instantaneous or accumulative invasion of drilling fluid filtrate, granting stability to well and production zones. Filter cake minimizes contact between drilling fluid filtrate and water, hydrocarbons and clay existent in formations. The uniform removal of the filter cake from the entire interval is a critical factor of the completion process. The main methods used to breaking filter cake are classified into two groups, external or internal, according to their removal mechanism. The aim of this work is the presentation of these mechanisms as well their efficiency. (author)

Garcia, Marcelo H.F. [Poland Quimica Ltda., Duque de Caxias, RJ (Brazil)

2004-07-01

189

Sub-micron filter  

Science.gov (United States)

Aluminum hydroxide fibers approximately 2 nanometers in diameter and with surface areas ranging from 200 to 650 m.sup.2/g have been found to be highly electropositive. When dispersed in water they are able to attach to and retain electronegative particles. When combined into a composite filter with other fibers or particles they can filter bacteria and nano size particulates such as viruses and colloidal particles at high flux through the filter. Such filters can be used for purification and sterilization of water, biological, medical and pharmaceutical fluids, and as a collector/concentrator for detection and assay of microbes and viruses. The alumina fibers are also capable of filtering sub-micron inorganic and metallic particles to produce ultra pure water. The fibers are suitable as a substrate for growth of cells. Macromolecules such as proteins may be separated from each other based on their electronegative charges.

Tepper, Frederick (Sanford, FL); Kaledin, Leonid (Port Orange, FL)

2009-10-13

190

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

191

Use of changing filters  

International Nuclear Information System (INIS)

The invention concerns a changing filter for accommodating bulk contact material, eg active carbons, for cleaning gas or air flows. The filter consists of a square, in which the meandering filter bed surrounded by perforated sheets with windings alternately towards the incoming and outgoing flow side is accommodated. The windings of the filter bed are flattened on the outgoing flow side, where the part of the perforated sheet partitions towards the flattened part is open on the outgoing flow side and can be closed by perforated sheet lids. Pressure plates with rubber or plastic mats permeable to air are laid on the filter bed below the perforated sheet lids and tensioned against the bed. The advantage is that while guaranteeing many applications, the danger of leaks to the mechanical parts of the closing lid is overcome. (orig./HP)

192

Particle Filtering: The Need for Speed  

Directory of Open Access Journals (Sweden)

Full Text Available The particle filter (PF has during the last decade been proposed for a wide range of localization and tracking applications. There is a general need in such embedded system to have a platform for efficient and scalable implementation of the PF. One such platform is the graphics processing unit (GPU, originally aimed to be used for fast rendering of graphics. To achieve this, GPUs are equipped with a parallel architecture which can be exploited for general-purpose computing on GPU (GPGPU as a complement to the central processing unit (CPU. In this paper, GPGPU techniques are used to make a parallel recursive Bayesian estimation implementation using particle filters. The modifications made to obtain a parallel particle filter, especially for the resampling step, are discussed and the performance of the resulting GPU implementation is compared to the one achieved with a traditional CPU implementation. The comparison is made using a minimal sensor network with bearings-only sensors. The resulting GPU filter, which is the first complete GPU implementation of a PF published to this date, is faster than the CPU filter when many particles are used, maintaining the same accuracy. The parallelization utilizes ideas that can be applicable for other applications.

Gustaf Hendeby

2010-01-01

193

Particle Filtering: The Need for Speed  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract The particle filter(PF has during the last decade been proposed for a wide range of localization and tracking applications. There is a general need in such embedded system to have a platform for efficient and scalable implementation of the PF. One such platform is the graphics processing unit (GPU, originally aimed to be used for fast rendering of graphics. To achieve this, GPUs are equipped with a parallel architecture which can be exploited for general-purpose computing on GPU (GPGPU as a complement to the central processing unit (CPU. In this paper, GPGPU techniques are used to make a parallel recursive Bayesian estimation implementation using particle filters. The modifications made to obtain a parallel particle filter, especially for the resampling step, are discussed and the performance of the resulting GPU implementation is compared to the one achieved with a traditional CPU implementation. The comparison is made using a minimal sensor network with bearings-only sensors. The resulting GPU filter, which is the first complete GPU implementation of a PF published to this date, is faster than the CPU filter when many particles are used, maintaining the same accuracy. The parallelization utilizes ideas that can be applicable for other applications.

Karlsson Rickard

2010-01-01

194

Network synthesis and filter design  

International Nuclear Information System (INIS)

This book deals with network synthesis and filter design. This contains twelve chapters, which includes Historical background, Network function on Historical background, network function on typical types, Hurwitz polynomials and LC network function on typical types, Hurwitz polynomials and LC network function, Filter function with transitional butter worth-chebyshev filters and step response and impulse response, Frequency transformation such as frequency scaling, LP : HP transformation, LP : BP transformation and LP : BS transformation, Basics of network synthesis, butter worth filter, chebyshev filter, sensitivity filter, chebyshev filter, sensitivity of circuitry, operational Amplifier and its apply, VCVS RC filter, Higher-order filter, OP Amp, Ladder network simulation and switched capacitor filter. It adds marks on butter worth filter and chebyshev filter.

195

Research on E-mail Filtering Based On Improved Bayesian  

Directory of Open Access Journals (Sweden)

Full Text Available Naive Bayesian has been widely used in spam filter because it simply and it also could classify texts more correctly and quickly. However, in the process of classifying and filtering, the traditional method doesn't consider the different features between the spam mail and the legitimate mail, and it also doesn't take into account the loss of misclassifying legitimate mail as spam, so there are many limitations of e-mail filtering. An improved algorithm based on Naïve Bayesian and Boosting method is proposed in this paper. The experiment result shows that the improved algorithm has better performance.

Pei-yu Liu

2009-03-01

196

Circular filter bag change ladderack system video presentation  

International Nuclear Information System (INIS)

A great deal of research and development at Harwell over the last few years has centered around the design of circular radial flow HEPA filters as alternatives to the traditional rectangular HEPA filter. With a circular insert there are inherent features which give this geometry certain advantages over its counterpart, such as ease of sealing, compatibility with remote handling and disposal routes; these have been well publicized in previous works. A mock-up is shown of a bag change ladderack system of 3400m3/h circular filter. It highlights the space requirements for bag changing and demonstrates the ease with which a filter may be replaced. The filter throat incorporates a silicone rubber lip seal which forms a flap seal against a tapered spigot feature built into the wall. The novelty of this filter design is that the bag is an integral part of the filter and is attached onto the filter flange. This enables the inside of the filter, where the contamination particulate has collected, to be sealed/bagged off and hence the dust burden retained

197

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

198

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

199

Ceramic filters for bulk inoculation of nickel alloy castings  

Directory of Open Access Journals (Sweden)

Full Text Available The work includes the results of research on production technology of ceramic filters which, besides the traditional filtering function, playalso the role of an inoculant modifying the macrostructure of cast nickel alloys. To play this additional role, filters should demonstratesufficient compression strength and ensure proper flow rate of liquid alloy. The role of an inoculant is played by cobalt aluminateintroduced to the composition of external coating in an amount from 5 to 10 wt.% . The required compression strength (over 1MPa isprovided by the supporting layers, deposited on the preform, which is a polyurethane foam. Based on a two-level fractional experiment24-1, the significance of an impact of various technological parameters (independent variables on selected functional parameters of theready filters was determined. Important effect of the number of the supporting layers and sintering temperature of filters after evaporationof polyurethane foam was stated.

F. Binczyk

2011-07-01

200

An Amplitude Spectral Capon Estimator with a Variable Filter Length  

DEFF Research Database (Denmark)

The filter bank methods have been a popular non-parametric way of computing the complex amplitude spectrum. So far, the length of the filters in these filter banks has been set to some constant value independently of the data. In this paper, we take the first step towards considering the filter length as an unknown parameter. Specifically, we derive a very simple and approximate way of determining the optimal filter length in a data-adaptive way. Based on this analysis, we also derive a model averaged version of the forward and the forward-backward amplitude spectral Capon estimators. Through simulations, we show that these estimators significantly improve the estimation accuracy compared to the traditional Capon estimators.

Nielsen, Jesper Kjær; Smaragdis, Paris

2012-01-01

 
 
 
 
201

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

202

Ceramic fiber reinforced filter  

Science.gov (United States)

A filter for removing particulate matter from high temperature flowing fluids, and in particular gases, that is reinforced with ceramic fibers. The filter has a ceramic base fiber material in the form of a fabric, felt, paper of the like, with the refractory fibers thereof coated with a thin layer of a protective and bonding refractory applied by chemical vapor deposition techniques. This coating causes each fiber to be physically joined to adjoining fibers so as to prevent movement of the fibers during use and to increase the strength and toughness of the composite filter. Further, the coating can be selected to minimize any reactions between the constituents of the fluids and the fibers. A description is given of the formation of a composite filter using a felt preform of commercial silicon carbide fibers together with the coating of these fibers with pure silicon carbide. Filter efficiency approaching 100% has been demonstrated with these filters. The fiber base material is alternately made from aluminosilicate fibers, zirconia fibers and alumina fibers. Coating with Al.sub.2 O.sub.3 is also described. Advanced configurations for the composite filter are suggested.

Stinton, David P. (Knoxville, TN); McLaughlin, Jerry C. (Oak Ridge, TN); Lowden, Richard A. (Powell, TN)

1991-01-01

203

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

204

A Reconfigurable FIR Filter System  

Directory of Open Access Journals (Sweden)

Full Text Available Introduced a practical reconfigurable FIR filter system. According to the filter specialties, the filter coefficients are calculated by the computer. And the configured coefficients of the multistage FIR filter are downloaded to the chip. The filtering computing is completed by the FPGA. All these make virtual value of voltage and current more accurate and steady, so reseach on FIR filter Algorithms is the emphases and difficulty. The performance testing and application examples are given to verify this system.

Guosheng Xu

2013-07-01

205

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

206

Minimum-Energy Distributed Filtering  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The paper addresses the problem of distributed filtering with guaranteed convergence properties using minimum-energy filtering and $H_\\infty$ filtering methodologies. A linear state space plant model is considered observed by a network of communicating sensors, in which individual sensor measurements may lead to an unobservable filtering problem. However, each filter locally shares estimates, that are subject to disturbances, with its respective neighboring filters to produc...

Zamani, Mohammad; Ugrinovskii, Valery

2014-01-01

207

EMI filter design  

CERN Document Server

With today's electrical and electronics systems requiring increased levels of performance and reliability, the design of robust EMI filters plays a critical role in EMC compliance. Using a mix of practical methods and theoretical analysis, EMI Filter Design, Third Edition presents both a hands-on and academic approach to the design of EMI filters and the selection of components values. The design approaches covered include matrix methods using table data and the use of Fourier analysis, Laplace transforms, and transfer function realization of LC structures. This edition has been fully revised

Ozenbaugh, Richard Lee

2011-01-01

208

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

209

New design of orthogonal filter banks using the Cayley transform  

Science.gov (United States)

It is a challenging task to design orthogonal filter banks, especially multidimensional (MD) ones. In the one-dimensional (1D) two-channel finite impulse response (FIR) filter bank case, several design methods exist. Among them, designs based on spectral factorizations (by Smith and Barnwell) and designs based on lattice factorizations (by Vaidynanathan and Hoang) are the most effective and widely used. The 1D two-channel infinite impulse response (IIR) filter banks and associated wavelets were considered by Herley and Vetterli. All of these design methods are based on spectral factorization. Since in multiple dimensions, there is no factorization theorem, traditional 1D design methods fail to generalize. Tensor products can be used to construct MD orthogonal filter banks from 1D orthogonal filter banks, yielding separable filter banks. In contrast to separable filter banks, nonseparable filter banks are designed directly, and result in more freedom and better frequency selectivity. In the FIR case, Kovacevic and Vetterli designed specific two-dimensional and three-dimensional nonseparable FIR orthogonal filter banks. In the IIR case, there are few design results (if any) for MD orthogonal IIR filter banks. To design orthogonal filter banks, we must design paraunitary matrices, which leads to solving sets of nonlinear equations. The Cayley transform establishes a one-to-one mapping between paraunitary matrices and para-skew-Hermitian matrices. In contrast to nonlinear equations, the para-skew-Hermitian condition amounts to linear constraints on the matrix entries which are much easier to solve. We present the complete characterization of both paraunitary FIR matrices and paraunitary IIR matrices in the Cayley domain. We also propose efficient design methods for MD orthogonal filter banks and corresponding methods to impose the vanishing-moment condition.

Zhou, Jianping; Do, Minh N.; Kovacevic, Jelena

2003-11-01

210

Fuzzy Stack Filters for Image Processing  

Directory of Open Access Journals (Sweden)

Full Text Available This paper is oriented to filtering by fuzzy stack filter of monochromatic images distorted with impulsive noise. Fuzzy stack filter is acquired by extension of stack filters by means of fuzzy logic. Adding some parameters to this filter, that are adjusted by neural adaptation algorithm, is obtained the new class of filters, so-called fuzzy rank-order filters. This class of filters is compared with other well known filters as stack filters and neural stack filters.

Cs. Stupak

1999-06-01

211

Adaptive digital filters  

CERN Document Server

“Adaptive Digital Filters” presents an important discipline applied to the domain of speech processing. The book first makes the reader acquainted with the basic terms of filtering and adaptive filtering, before introducing the field of advanced modern algorithms, some of which are contributed by the authors themselves. Working in the field of adaptive signal processing requires the use of complex mathematical tools. The book offers a detailed presentation of the mathematical models that is clear and consistent, an approach that allows everyone with a college level of mathematics knowledge to successfully follow the mathematical derivations and descriptions of algorithms.   The algorithms are presented in flow charts, which facilitates their practical implementation. The book presents many experimental results and treats the aspects of practical application of adaptive filtering in real systems, making it a valuable resource for both undergraduate and graduate students, and for all others interested in m...

Kova?evi?, Branko; Milosavljevi?, Milan

2013-01-01

212

ACS Ramp Filter Test  

Science.gov (United States)

This program has 2 main goals: 1} to verify that the desired wavelength has been correctly placed over the corresponding ramp filter aperture; 2} to measure the throughput at a few selected wavelengths as a function of position within the ramp filter monochomatic FOV. These measurements will be carried out by imaging a known and well observed {both HST and ground-based} planetary nebula {PN} in several key emission lines - [OII] 3727, [OIII] 5007, H-alpha+[NII] and/or [SII] 6717, 6731. These 3 {4} emission lines fall onto three separate middle ramp segments - FR388N, FR505N, and FR656N - and will allow intercomparison between the ACS ramp filters and fixed bandpass narrow-band filters F502N {[OIII] 5007} and F658N {H-alpha + [NII]} for both the WFC and HRC detectors.

Tsvetanov, Zlatan

2001-07-01

213

Learning Separable Filters  

Digital Repository Infrastructure Vision for European Research (DRIVER)

While learned image features can achieve great accuracy on different Computer Vision problems, their use in real-world situations is still very limited as their extraction is typically time-consuming. We therefore propose a method to learn image features that can be extracted very efficiently using separable filters, by looking for low rank filters. We evaluate our approach on both the image categorization and the pixel classification tasks and show that we obtain similar accuracy as state-of...

Rigamonti, Roberto; Lepetit, Vincent; Fua, Pascal

2012-01-01

214

Spatial filter issues  

International Nuclear Information System (INIS)

Experiments and calculations indicate that the threshold pressure in spatial filters for distortion of a transmitted pulse scales approximately as IO.2 and (F number-sign)2 over the intensity range from 1014 to 2xlO15 W/CM2 . We also demonstrated an interferometric diagnostic that will be used to measure the scaling relationships governing pinhole closure in spatial filters

215

Kalman Filtering in R  

Directory of Open Access Journals (Sweden)

Full Text Available Support in R for state space estimation via Kalman filtering was limited to one package, until fairly recently. In the last five years, the situation has changed with no less than four additional packages offering general implementations of the Kalman filter, including in some cases smoothing, simulation smoothing and other functionality. This paper reviews some of the offerings in R to help the prospective user to make an informed choice.

Fernando Tusell

2011-03-01

216

Containment venting filter designs incorporating stainless-steel fiber filters  

International Nuclear Information System (INIS)

Failure of the containment of a PWR as a consequence of a major reactor accident can be prevented by filtered containment venting into the stack through an accident filter system. This greatly reduces the environmental contamination by fission products, which otherwise would be released. Possible filter concepts and their embodiment in stainless-steel fiber filters are described. (orig./HP)

217

Miniaturized superconducting microwave filters  

Energy Technology Data Exchange (ETDEWEB)

In this paper we present methods for the miniaturization of superconducting filters. We consider two designs of seventh-order bandpass Chebyshev filters based on lumped elements and a novel quasi-lumped element resonator. In both designs the area of the filters, with a central frequency of 2-5 GHz, is less than 1.2 mm{sup 2}. Such small filters can be readily integrated on a single board for multi-channel microwave control of superconducting qubits. The filters have been experimentally tested and the results are compared with simulations. The miniaturization resulted in parasitic coupling between resonators and within each resonator that affected primarily the stopband and increased the bandwidth. The severity of the error depends on the design in particular, and was less sensitive when a groundplane was used under the inductances of the resonators. The best performance was reached for the quasi-lumped filter with central frequency of 4.45 GHz, quality factor of 40 and 50 dB stopband.

Rafique, M R; Ohki, T; Banik, B; Engseth, H; Linner, P; Herr, A [Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Goteborg (Sweden)], E-mail: raihan.rafique@mc2.chalmers.se

2008-07-15

218

Miniaturized superconducting microwave filters  

Science.gov (United States)

In this paper we present methods for the miniaturization of superconducting filters. We consider two designs of seventh-order bandpass Chebyshev filters based on lumped elements and a novel quasi-lumped element resonator. In both designs the area of the filters, with a central frequency of 2-5 GHz, is less than 1.2 mm2. Such small filters can be readily integrated on a single board for multi-channel microwave control of superconducting qubits. The filters have been experimentally tested and the results are compared with simulations. The miniaturization resulted in parasitic coupling between resonators and within each resonator that affected primarily the stopband and increased the bandwidth. The severity of the error depends on the design in particular, and was less sensitive when a groundplane was used under the inductances of the resonators. The best performance was reached for the quasi-lumped filter with central frequency of 4.45 GHz, quality factor of 40 and 50 dB stopband.

Rafique, M. R.; Ohki, T.; Banik, B.; Engseth, H.; Linner, P.; Herr, A.

2008-07-01

219

Miniaturized superconducting microwave filters  

International Nuclear Information System (INIS)

In this paper we present methods for the miniaturization of superconducting filters. We consider two designs of seventh-order bandpass Chebyshev filters based on lumped elements and a novel quasi-lumped element resonator. In both designs the area of the filters, with a central frequency of 2-5 GHz, is less than 1.2 mm2. Such small filters can be readily integrated on a single board for multi-channel microwave control of superconducting qubits. The filters have been experimentally tested and the results are compared with simulations. The miniaturization resulted in parasitic coupling between resonators and within each resonator that affected primarily the stopband and increased the bandwidth. The severity of the error depends on the design in particular, and was less sensitive when a groundplane was used under the inductances of the resonators. The best performance was reached for the quasi-lumped filter with central frequency of 4.45 GHz, quality factor of 40 and 50 dB stopband

220

Mirrors as power filters  

International Nuclear Information System (INIS)

X-ray mirrors are often positioned as the first optical element in synchrotron radiation beamlines because of their ability to focus, collimate and deviate x-rays and because of their spectral filtering ability. Conventional total reflection mirrors act as low-pass spectral filters, while multilayer interference mirrors act as band-pass spectral filters. This is demonstrated in this paper, which shows calculated reflectance profiles for flat platinum total reflection and tungsten/carbon multilayer mirrors positioned in angle to reflect 8 keV x-rays with a minimum of reflected total reflected power. The band-pass reflectance of the multilayer mirror reduces the power reflected down the beamline compared to the low-pass reflectance of the total reflection mirror, assuming a broad-band x-ray source such as a bending magnet or wiggler. This reduction in integrated power reflected by the multilayer mirror compared to the total reflection mirror has lead to the suggestion that multilayer mirrors might act as power filters to reduce unwanted reflected power which can produce thermal distortions in grating and crystal monochromators which could spoil their high resolution performance. Such power filtering might be especially attractive at the third generation of high-brightness synchrotron radiation facilities currently under construction, where x-ray beams with unprecedented power densities will be produced. Some experimental progress towards using multilayers as power filters in bending magnet beams at existing synchrotron radiation sources has already occurred

 
 
 
 
221

Use of naturally occurring radon progeny for in-place testing of high-efficiency particulate air filters  

International Nuclear Information System (INIS)

High-efficiency particulate air (HEPA) filters are routinely used to control emissions of radioactive particles from nuclear facilities. Because HEPA filters play a critical role in protecting members of the public and the environment, there are stringent requirements for verifying the efficiency of HEPA filters prior to their installation and during their use. Traditional methods for the performance tests involve introducing a challenge aerosol before the filter and comparing the concentration of particles before and after the filter. We describe a proof-of-principle test for evaluating use of naturally occurring radon progeny for testing HEPA filters

222

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

223

Analog filters in nanometer CMOS  

CERN Document Server

Starting from the basics of analog filters and the poor transistor characteristics in nanometer CMOS 10 high-performance analog filters developed by the authors in 120 nm and 65 nm CMOS are described extensively. Among them are gm-C filters, current-mode filters, and active filters for system-on-chip realization for Bluetooth, WCDMA, UWB, DVB-H, and LTE applications. For the active filters several operational amplifier designs are described. The book, furthermore, contains a review of the newest state of research on low-voltage low-power analog filters. To cover the topic of the book comprehen

Uhrmann, Heimo; Zimmermann, Horst

2013-01-01

224

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

225

An IIR median hybrid filter  

Science.gov (United States)

A new class of nonlinear filters, the so-called class of multidirectional infinite impulse response median hybrid filters, is presented and analyzed. The input signal is processed twice using a linear shift-invariant infinite impulse response filtering module: once with normal causality and a second time with inverted causality. The final output of the MIMH filter is the median of the two-directional outputs and the original input signal. Thus, the MIMH filter is a concatenation of linear filtering and nonlinear filtering (a median filtering module). Because of this unique scheme, the MIMH filter possesses many desirable properties which are both proven and analyzed (including impulse removal, step preservation, and noise suppression). A comparison to other existing median type filters is also provided.

Bauer, Peter H.; Sartori, Michael A.; Bryden, Timothy M.

1992-01-01

226

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

227

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

228

Gas Path Health Monitoring for a Turbofan Engine Based on a Nonlinear Filtering Approach  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Different approaches for gas path performance estimation of dynamic systems are commonly used, the most common being the variants of the Kalman filter. The extended Kalman filter (EKF) method is a popular approach for nonlinear systems which combines the traditional Kalman filtering and linearization techniques to effectively deal with weakly nonlinear and non-Gaussian problems. Its mathematical formulation is based on the assumption that the probability density function (PDF) of the state ve...

Yiqiu Lv; Feng Lu; Jinquan Huang

2013-01-01

229

A Robust Collaborative Filtering Recommendation Algorithm Based on Multidimensional Trust Model  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Collaborative filtering is one of the widely used technologies in the e-commerce recommender systems. It can predict the interests of a user based on the rating information of many other users. But the traditional collaborative filtering recommendation algorithm has the problems such as lower recommendation precision and weaker robustness. To solve these problems, in this paper we present a robust collaborative filtering recommendation algorithm based on multidimensional trust model. Firstly,...

Dongyan Jia; Fuzhi Zhang; Sai Liu

2013-01-01

230

CSA noise measurement used on oscilloscope and digital filter  

International Nuclear Information System (INIS)

A new method for measurement of low noise Charge Sensitive Preamplifier, with digital oscilloscope and digital filter is discussed in this paper. Compared with traditional measurement, this method has advantage of flexible parameters and convenient to use. The test result is reasonably accords with conventional result. (authors)

231

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

232

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

233

Filters for Submillimeter Electromagnetic Waves  

Science.gov (United States)

New manufacturing process produces filters strong, yet have small, precise dimensions and smooth surface finish essential for dichroic filtering at submillimeter wavelengths. Many filters, each one essentially wafer containing fine metal grid made at same time. Stacked square wires plated, fused, and etched to form arrays of holes. Grid of nickel and tin held in brass ring. Wall thickness, thickness of filter (hole depth) and lateral hole dimensions all depend upon operating frequency and filter characteristics.

Berdahl, C. M.

1986-01-01

234

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

235

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.

236

State space second order filter estimation  

Directory of Open Access Journals (Sweden)

Full Text Available 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 properties 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

2013-01-01

237

Computing a Comprehensible Model for Spam Filtering  

Science.gov (United States)

In this paper, we describe the application of the Desicion Tree Boosting (DTB) learning model to spam email filtering.This classification task implies the learning in a high dimensional feature space. So, it is an example of how the DTB algorithm performs in such feature space problems. In [1], it has been shown that hypotheses computed by the DTB model are more comprehensible that the ones computed by another ensemble methods. Hence, this paper tries to show that the DTB algorithm maintains the same comprehensibility of hypothesis in high dimensional feature space problems while achieving the performance of other ensemble methods. Four traditional evaluation measures (precision, recall, F1 and accuracy) have been considered for performance comparison between DTB and others models usually applied to spam email filtering. The size of the hypothesis computed by a DTB is smaller and more comprehensible than the hypothesis computed by Adaboost and Naïve Bayes.

Ruiz-Sepúlveda, Amparo; Triviño-Rodriguez, José L.; Morales-Bueno, Rafael

238

A FUZZY FILTERING MODEL FOR CONTOUR DETECTION  

Directory of Open Access Journals (Sweden)

Full Text Available Contour detection is the basic property of image processing. Fuzzy Filtering technique is proposed to generate thick edges in two dimensional gray images. Fuzzy logic is applied to extract value for an image and is used for object contour detection. Fuzzy based pixel selection can reduce the drawbacks of conventional methods(Prewitt, Robert. In the traditional methods, filter mask is used for all kinds of images. It may succeed in one kind of image but fail in another one. In this frame work the threshold parameter values are obtained from the fuzzy histogram of the input image. The Fuzzy inference method selects the complete information about the border of the object and the resultant image has less impulse noise and the contrast of the edge is increased. The extracted object contour is thicker than the existing methods. The performance of the algorithm is tested with Peak Signal Noise Ratio(PSNR and Complex Wavelet Structural Similarity Metrics(CWSSIM.

T.C. Rajakumar

2011-04-01

239

Intraindividual evaluation of the influence of iterative reconstruction and filter kernel on subjective and objective image quality in computed tomography of the brain  

International Nuclear Information System (INIS)

Objectives: To intraindividually evaluate the potential of 4th generation iterative reconstruction (IR) on brain CT with regard to subjective and objective image quality. Methods: 31 consecutive raw data sets of clinical routine native sequential brain CT scans were reconstructed with IR level 0 (= filtered back projection), 1, 3 and 4; 3 different brain filter kernels (smooth/standard/sharp) were applied respectively. Five independent radiologists with different levels of experience performed subjective image rating. Detailed ROI analysis of image contrast and noise was performed. Statistical analysis was carried out by applying a random intercept model. Results: Subjective scores for the smooth and the standard kernels were best at low IR levels, but both, in particular the smooth kernel, scored inferior with an increasing IR level. The sharp kernel scored lowest at IR 0, while the scores substantially increased at high IR levels, reaching significantly best scores at IR 4. Objective measurements revealed an overall increase in contrast-to-noise ratio at higher IR levels, which was highest when applying the soft filter kernel. The absolute grey-white contrast decreased with an increasing IR level and was highest when applying the sharp filter kernel. All subjective effects were independent of the raters' experience and the patients' age and sex. Conclusion: Different combinations of IR level and filter kernel substantially influence subjective and objective image quality of brain CT. (orig.)

240

Multilevel Mixture Kalman Filter  

Directory of Open Access Journals (Sweden)

Full Text Available The mixture Kalman filter is a general sequential Monte Carlo technique for conditional linear dynamic systems. It generates samples of some indicator variables recursively based on sequential importance sampling (SIS and integrates out the linear and Gaussian state variables conditioned on these indicators. Due to the marginalization process, the complexity of the mixture Kalman filter is quite high if the dimension of the indicator sampling space is high. In this paper, we address this difficulty by developing a new Monte Carlo sampling scheme, namely, the multilevel mixture Kalman filter. The basic idea is to make use of the multilevel or hierarchical structure of the space from which the indicator variables take values. That is, we draw samples in a multilevel fashion, beginning with sampling from the highest-level sampling space and then draw samples from the associate subspace of the newly drawn samples in a lower-level sampling space, until reaching the desired sampling space. Such a multilevel sampling scheme can be used in conjunction with the delayed estimation method, such as the delayed-sample method, resulting in delayed multilevel mixture Kalman filter. Examples in wireless communication, specifically the coherent and noncoherent 16-QAM over flat-fading channels, are provided to demonstrate the performance of the proposed multilevel mixture Kalman filter.

Xiaodong Wang

2004-11-01

 
 
 
 
241

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

242

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 disposable HEPA filters, thus presenting a route to reduce ultimate disposal volumes and secondary waste streams. (authors)

243

An area efficient low noise 100 Hz low-pass filter  

DEFF Research Database (Denmark)

A technique based on scaling a filter's capacitor currents to improve the noise performance of low frequency continuous-time filters is presented. Two 100 Hz low-pass filters have been implemented: a traditional low pass filter (as reference), and a filter utilizing the above mentioned current scaling technique. The two filters utilize approximately the same silicon area. The scaled filter implements the scaling by use of a MOS based current conveyor type CCII. Measurements indicate that the current scaled filter results in a noise improvement of approximately 5.5 dB over the reference filter when a class A/B biasing scheme is used in the current divider. Obtaining identical noise performance from the reference filter would require a 3.6 times larger filter capacitor. This would increase the reference filter's die area by 100%. Therefore, the current scaling technique allows filters with improved noise performance/dynamic range, given a fixed silicon area and a fixed power supply

Perch-Nielsen, Ivan R.

1996-01-01

244

Efficient synthesis of gaussian filters by cascaded uniform filters.  

Science.gov (United States)

Gaussian filtering is an important tool in image processing and computer vision. In this paper we discuss the background of Gaussian filtering and look at some methods for implementing it. Consideration of the central limit theorem suggests using a cascade of ``simple'' filters as a means of computing Gaussian filters. Among ``simple'' filters, uniform-coefficient finite-impulse-response digital filters are especially economical to implement. The idea of cascaded uniform filters has been around for a while [13], [16]. We show that this method is economical to implement, has good filtering characteristics, and is appropriate for hardware implementation. We point out an equivalence to one of Burt's methods [1], [3] under certain circumstances. As an extension, we describe an approach to implementing a Gaussian Pyramid which requires approximately two addition operations per pixel, per level, per dimension. We examine tradeoffs in choosing an algorithm for Gaussian filtering, and finally discuss an implementation. PMID:21869341

Wells, W M

1986-02-01

245

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

246

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

247

Ferroelectric electronically tunable filters  

International Nuclear Information System (INIS)

A cylindrical cavity is loaded with a ferroelectric rod and is resonant at the dominant mode. The loaded cylindrical cavity is a band pass filter. As a bias voltage is applied across the ferroelectric rod, its permittivity changes resulting in a new resonant frequency for the loaded cylindrical cavity. The ferroelectric rod is operated at a temperature slightly above its Curie temperature. The loaded cylindrical cavity is kept at a constant designed temperature. The cylindrical cavity is made of conductors, a single crystal high Tc superconductor including YBCO and a single crystal dielectric, including sapphire and lanthanum aluminate, the interior conducting surfaces of which are deposited with a film of a single crystal high Tc superconductor. Embodiments also include waveguide single and multiple cavity type tunable filters. Embodiments also include tunable band reject filters. 10 figs

248

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

249

A survey of PHD filter and CPHD filter implementations  

Science.gov (United States)

The probability hypothesis density (PHD) filter has attracted increasing interest since the author first introduced it in 2000. Potentially practical computational implementations of this filter have been devised, based on sequential Monte Carlo or on Gaussian mixture techniques. Research groups in at least a dozen different nations are investigating the PHD filter and its generalization, the CPHD filter, for use in various applications. Some of this work suggests that these filters may, under certain circumstances, outperform conventional multitarget filters such as MHT and JPDA. This paper summarizes these research efforts and their findings.

Maher, Ronald

2007-04-01

250

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

251

Subwavelength grating filtering devices.  

Science.gov (United States)

We propose and simulate the characteristics of optical filters based on subwavelength gratings. In particular, we demonstrate through numerical simulations the feasibility of implementing SWG Bragg gratings in silicon-on-insulator (SOI). We also propose SWG ring resonators in SOI and verify their operation using numerical simulations and experiments. The fabricated devices exhibit an extinction ratio as large as 30 dB and a Q-factor as high as ~20,000. These fundamental SWG filters can serve as building blocks for more complex devices. PMID:24977793

Wang, Junjia; Glesk, Ivan; Chen, Lawrence R

2014-06-30

252

Broadband filter design  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This thesis presents the design of an active filter implemented in a 65nm CMOS technology and based on super source follower. The original filter was 5th order low-pass Chebyshev-type with a cut-off frequency of 160 MHz, but it was to be changed into Butterworth-type because of the results, here both designs are shown. The architecture is fully differential and it is based on Sallen-Key biquad structures with super source follower as an active element and resistors and capacitors as passive e...

Valero Sarmiento, Jose Manuel

2010-01-01

253

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.

Frydendall, Jan; Madsen, Henrik

2012-01-01

254

Filtered neutron beams  

International Nuclear Information System (INIS)

The need to control exposure of personnel to neutrons is becoming increasingly important. A proportion of the dose equivalent in the vicinity of neutron-producing facilities such as power reactors results from neutrons at intermediate energies (thermal to about 0.1MeV). This energy range poses particular problems for radiation protection and there is a requirement to develop sources of monoenergetic neutrons in this energy region. The need for such sources and how they may be realised using neutron filters in conjunction with a high-flux reactor is discussed. Such filtered neutron beams are potentially useful in many areas of science and technology. (author)

255

Digital filters in spectrometry  

International Nuclear Information System (INIS)

In this work is presented the development and application of the digital signal processing for different multichannel analysis spectra. The use of the smoothing classic methods in applications of signal processing is illustrated by a filters discussion; autoregressive, mobile average and the ARMA filters. Generally, simple routines of lineal smoothing do not provide appropriate smoothing of the data that show the local ruggedness as the strong discontinuities; however the indicated development algorithms have been enough to leave adapting to this task. Four algorithms were proven: autoregressive, mobile average, ARMA and binomial methods for 5, 7, and 9 of data, everything in the domain of the time and programmed in Mat lab. (Author)

256

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

257

Fabrication of guided mode resonance filters on conformal surfaces  

Science.gov (United States)

The guided mode resonance (GMR) phenomena has been studied and exploited for applications in sensors, polarizers, dichroic laser mirrors, and more. These micro-optical structures serve as highly functional devices capable of narrowband spectral filtering. Their relatively simple design includes a subwavelength periodically modulated index layer and a waveguiding layer. This configuration yields efficient and easily tunable devices over a broad range of wavelengths. Currently GMR filters have been fabricated exclusively on flat surfaces. In this paper, we demonstrate fabrication of GMR filters on conformal surfaces using non-traditional techniques. Flexible molds are used as replication templates in a micro-transfer molding process. SU-8 negative photoresist serves as the molded polymer with good thermal characteristics compatible with subsequent deposition of dielectric layers. Fabrication procedures for GMR filters at near-IR wavelengths on concave lens surfaces are discussed, and initial experimental results are presented.

Cannistra, A. T.; Poutous, M. K.; Johnson, E. G.; Suleski, T. J.

2011-02-01

258

Active pre-filters for dc/dc Boost regulators  

Directory of Open Access Journals (Sweden)

Full Text Available This paper proposes an active pre-filter to mitigate the current harmonics generated by classical dc/dc Boost regulators, which generate current ripples proportional to the duty cycle. Therefore, high output voltage conditions, i.e., high voltage conversion ratios, produce high current harmonics that must be filtered to avoid damage or source losses. Traditionally, these current components are filtered using electrolytic capacitors, which introduce reliability problems because of their high failure rate. The solution introduced in this paper instead uses a dc/dc converter based on the parallel connection of the Boost canonical cells to filter the current ripples generated by the Boost regulator, improving the system reliability. This solution provides the additional benefits of improving the overall efficiency and the voltage conversion ratio. Finally, the solution is validated with simulations and experimental results.

Carlos Andrés Ramos-Paja

2014-07-01

259

Toward Directly-Deposited Optical Blocking Filters for High-performance, Back-illuminated Imaging X-ray Detectors  

Science.gov (United States)

Silicon X-ray detectors require optical blocking filters to prevent out-of-band (UV, visible and near-IR) radiation from corrupting the X-ray signal. Traditionally, blocking filters have been deposited on thin, free-standing membranes suspended over the detector. Free-standing filters are fragile, however, and in past instruments have required heavy and complex vacuum housings to protect them from acoustic loads during ground operations and launch. A directly-deposited blocking filter greatly simplifies the instrument and in principle permits better soft X-ray detection efficiency than a traditional free-standing filter. Directly-deposited filters have flown in previous generation instruments (e.g. the XMM/Newton Reflection Grating Spectrometer) but none has yet been demonstrated on a modern, high-performance back-illuminated X-ray CCD. We report here on the status of our NASA-funded Strategic Astrophysics Technology program to demonstrate such filters.

Bautz, Mark W.; Kissel, S. E.; Ryu, K.; Suntharalingam, V.

2014-01-01

260

Is Traditional Educational Media Dead?  

Science.gov (United States)

Discusses the influence of films on the author and concludes that traditional media has not died out, but rather has changed due to technology. Films are now watched on television as well as at a cinema; radio is more pervasive; and newspapers are still valued. (LRW)

Ljubic, Milan

2000-01-01

 
 
 
 
261

From Traditional to Virtual Mentoring.  

Science.gov (United States)

The tradition of a mentoring relationship is embedded in a personal/business relationship between a wise teacher and someone who needs to learn a trade. Learning sessions have occurred over the years in many types of settings, including one-on-one mentoring, conferences, meetings, telephone, and fax. As society looks to technology as a vital…

Kirk, James J.; Olinger, Jennifer

262

Contemporary Literature/Traditional Curriculum.  

Science.gov (United States)

An upper school English program has been experimenting with ways to reinforce its traditional literary curriculum with contemporary works. Three contemporary novels in particular (Naylor's "The Women of Brewster Place," Walker's "The Color Purple," and Miller's "A Canticle for Leibowitz") have been found to foster a sense of continuity with the…

Spencer, Jamieson

263

The Dual Carrier ABSK System Based on a FIR Bandpass Filter  

Science.gov (United States)

The special impacting filter (SIF) with IIR structure has been used to demodulate ABSK signals. The key points of SIF, including the resonance circuit's high Q value and the “slope-phase discrimination” character of the filter sideband, are demonstrated in the paper. The FIR narrow-band bandpass filtering system, which can also provide the impact-filtering effect, is proposed. A dual carrier system of ABSK signals is designed with the proposed FIR filter as its receiver. The simulation results show that the FIR filter can work well. Moreover, compared to the traditional SIF, the proposed FIR filter can not only achieve higher spectral efficiency, but also give better demodulation performance. PMID:24658625

Chen, Zhimin; Wu, Lenan; Wang, Jiwu

2014-01-01

264

The Dual Carrier ABSK System Based on a FIR Bandpass Filter  

Directory of Open Access Journals (Sweden)

Full Text Available The special impacting filter (SIF with IIR structure has been used to demodulate ABSK signals. The key points of SIF, including the resonance circuit’s high Q value and the “slope-phase discrimination” character of the filter sideband, are demonstrated in the paper. The FIR narrow-band bandpass filtering system, which can also provide the impact-filtering effect, is proposed. A dual carrier system of ABSK signals is designed with the proposed FIR filter as its receiver. The simulation results show that the FIR filter can work well. Moreover, compared to the traditional SIF, the proposed FIR filter can not only achieve higher spectral efficiency, but also give better demodulation performance.

Zhimin Chen

2014-03-01

265

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.

266

Device for automatic filter changing  

International Nuclear Information System (INIS)

A filter is moved from a store to an aerosol pipe by a lifting device and is clamped there. At the end of the operating period, the lifting device moves a new filter to a parking place. Control is from limit switches of the lifting, clamping and thrust devices and the position control of the store is by the limit switches. The filter changing device is enclosed in a gastight case, prevents blockage of a filter and makes it possible to set a certain operating period, to change the filter without interrupting the aerosol flow and to measure each filter in the sequence of operation outside the aerosol flow. (orig./HP)

267

Building material and filters  

...to produce a variety of building materials e.g. peat moss mixed...g. peat moss mixed with materials such as tar made a...who could not afford traditional building materials used dried block of turf...

268

Filter assembly for metallic and intermetallic tube filters  

Science.gov (United States)

A filter assembly (60) for holding a filter element (28) within a hot gas cleanup system pressure vessel is provided, containing: a filter housing (62), said filter housing having a certain axial length and having a peripheral sidewall, said sidewall defining an interior chamber (66); a one piece, all metal, fail-safe/regenerator device (68) within the interior chamber (66) of the filter housing (62) and/or extending beyond the axial length of the filter housing, said device containing an outward extending radial flange (71) within the filter housing for seating an essential seal (70), the device also having heat transfer media (72) disposed inside and screens (80) for particulate removal; one compliant gasket (70) positioned next to and above the outward extending radial flange of the fail-safe/regenerator device; and a porous metallic corrosion resistant superalloy type filter element body welded at the bottom of the metal fail-safe/regenerator device.

Alvin, Mary Anne (113 Lehr Ave., Pittsburgh, PA 15223); Lippert, Thomas E. (3205 Cambridge Rd., Murrysville, PA 15668); Bruck, Gerald J. (4469 Sardis Rd., Murrysville, PA 15668); Smeltzer, Eugene E. (R.D. 7, Box 267-I, Italy Rd., Export, PA 15632-9621)

2001-01-01

269

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

270

Ceramic HEPA Filter Program  

International Nuclear Information System (INIS)

Potential benefits of ceramic filters in nuclear facilities: (1) Short term benefit for DOE, NRC, and industry - (a) CalPoly HTTU provides unique testing capability to answer questions for DOE - High temperature testing of materials, components, filter, (b) Several DNFSB correspondences and presentations by DNFSB members have highlighted the need for HEPA filter R and D - DNFSB Recommendation 2009-2 highlighted a nuclear facility response to an evaluation basis earthquake followed by a fire (aka shake-n-bake) and CalPoly has capability for a shake-n-bake test; (2) Intermediate term benefit for DOE and industry - (a) Filtration for specialty applications, e.g., explosive applications at Nevada, (b) Spin-off technologies applicable to other commercial industries; and (3) Long term benefit for DOE, NRC, and industry - (a) Across industry, strong desire for better performance filter, (b) Engineering solution to safety problem will improve facility safety and decrease dependence on associated support systems, (c) Large potential life-cycle cost savings, and (d) Facilitates development and deployment of LLNL process innovations to allow continuous ventilation system operation during a fire.

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

Spot- Zombie Filtering System  

Directory of Open Access Journals (Sweden)

Full Text Available A major security challenge on the Internet is the existence of the large number of compromised machines. Such machines have been increasingly used to launch various security attacks including spamming and spreading malware, DDoS, and identity theft. These compromised machines are called “Zombies”. In general E-mail applications and providers uses spam filters to filter the spam messages. Spam filtering is a technique for discriminating the genuine message from the spam messages. The attackers send the spam messages to the targeted machine by exalting the filters, which causes the increase in false positives and false negatives. We develop an effective spam zombie detection system named SPOT by monitoring outgoing messages of a network. SPOT focuses on the number of outgoing messages that are originated or forwarded by each computer on a network to identify the presence of Zombies. SPOT is designed based on a powerful statistical tool called Sequential Probability Ratio Test, which has bounded false positive and false negative error rates.

Arathy Rajagopal

2014-01-01

273

Mirrors as power filters  

International Nuclear Information System (INIS)

Multilayer mirrors offer advantages in power filtering compared to total reflection mirrors in both wiggler and undulator beams at third generation synchrotron radiation sources currently under construction. These advantages come at the expense of increased absorbed power in the mirror itself, and of added complexity of beamline optical design. This paper discusses these aspects

274

The Kalman filter  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The kalman Filter developed in the early sixties by R. E. Kalman is a recursive state estimator for partially observed non-stationary stochastic prosses. It gives an optimal estimate in the least squares sense of the actual value of state vector from noisy observations.

Andrade Cetto, Juan

2002-01-01

275

Traditional Smallpox Vaccines and Atopic Dermatitis  

Science.gov (United States)

... DONATE Ways to Donate Traditional Smallpox Vaccines and Atopic Dermatitis Frequently Asked Questions What is the traditional smallpox ... vaccines to the traditional vaccine for people with atopic dermatitis/eczema, or for their close contacts? Yes. In ...

276

Real Time Digital Filters: Finite Impulse?Response Filters  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

277

Generalized Selection Weighted Vector Filters  

Directory of Open Access Journals (Sweden)

Full Text Available This paper introduces a class of nonlinear multichannel filters capable of removing impulsive noise in color images. The here-proposed generalized selection weighted vector filter class constitutes a powerful filtering framework for multichannel signal processing. Previously defined multichannel filters such as vector median filter, basic vector directional filter, directional-distance filter, weighted vector median filters, and weighted vector directional filters are treated from a global viewpoint using the proposed framework. Robust order-statistic concepts and increased degree of freedom in filter design make the proposed method attractive for a variety of applications. Introduced multichannel sigmoidal adaptation of the filter parameters and its modifications allow to accommodate the filter parameters to varying signal and noise statistics. Simulation studies reported in this paper indicate that the proposed filter class is computationally attractive, yields excellent performance, and is able to preserve fine details and color information while efficiently suppressing impulsive noise. This paper is an extended version of the paper by Lukac et al. presented at the 2003 IEEE-EURASIP Workshop on Nonlinear Signal and Image Processing (NSIP '03 in Grado, Italy.

Rastislav Lukac

2004-09-01

278

Positive implicative ordered filters of implicative semigroups  

Directory of Open Access Journals (Sweden)

Full Text Available We introduce the notion of positive implicative ordered filters in implicative semigroups. We show that every positive implicative ordered filter is both an ordered filter and an implicative ordered filter. We give examples that an ordered filter (an implicative ordered filter may not be a positive implicative ordered filter. We also give equivalent conditions of positive implicative ordered filters. Finally we establish the extension property for positive implicative ordered filters.

Kyung Ho Kim

2000-06-01

279

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

280

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.

 
 
 
 
281

Active resistance capacitance filter design  

Science.gov (United States)

Filters, formed by combinations of distributed RC elements with positive-feedback voltage amplifiers, provide transfer functions similar to those the heavier LC filters ordinarily employ. They also provide signal amplification.

Kerwin, W. J.

1970-01-01

282

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

283

Radiopasteurization of traditional herbal medicine  

International Nuclear Information System (INIS)

Investigation on the effects of irradiation using pasteurization dose of 500 krad (5kGy) on microbes contaminating traditional herbal medicine, produced by 3 large manufacturers in Indonesia, was carried out. Storage effects on microbial count moisture content of traditional herbal medicine packed in microbe tight packages, were also observed. The results showed that initial bacterial counts varied between 104 and 108 per gram, and mould and yeast counts varied between 0 and 105 per gram. These numbers decreased as much as 2 to 5 log cycles after irradiation with 500 krad. After 6 month storage, bacterial counts of irradiated samples decreased as much as 0 to 103 per gram. Initial moisture content varied from 5 to 12% and after 6 month storage the moisture content of most samples increased as much as 0 to 5%. Irradiated samples were found to be mould free, and most of the surviving microbes consisted of spore forming aerobic bacteria and yeast. (author)

284

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

285

What is traditional pastoral farming?  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The number of pastoralists maintaining production systems with small numbers of traditional breeds of cattle decreased dramatically with the modernisation and industrialisation of agriculture in Europe during the twentieth century. While these pastoral systems were not compatible with agricultural industrialisation policies, they provide a far better match to current European Union (EU) policy with its emphasis on high nature values and various cultural heritage protection measures. Today, th...

Eriksson, Camilla

2011-01-01

286

Software Development: Agile vs. Traditional  

Directory of Open Access Journals (Sweden)

Full Text Available 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.

Marian STOICA

2013-01-01

287

Augustine and the phenomenological tradition  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This essay traces the reception of Augustine in the 20th and 21st century phenomenological tradition. It gives special attention to recent monographs on Augustine by Jean-Luc Marion and Jean-Louis Chrétien, but contextualises these both fore (by examining the earlier work of Edmund Husserl and Martin Heidegger, as well as earlier and less determinative Augustinian engagements by Marion and Chrétien) and aft (by critically considering the philosophical, philological and theological implicati...

Biebighauser, Jeffrey

2012-01-01

288

TRADITIONAL FERMENTED FOODS OF LESOTHO  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper describes the traditional methods of preparing fermented foods and beverages of Lesotho. Information on the preparation methods was obtained through a combination of literature review and face to face interviews with respondents from Roma in Lesotho. An unstructured questionnaire was used to capture information on the processes, raw materials and utensils used. Four products; motoho (a fermented porridge), Sesotho (a sorghum based alcoholic beverage), hopose (sorghum fermented beer...

Gadaga, Tendekayi H.; Molupe Lehohla; Victor Ntuli

2013-01-01

289

Post-traditional corporate governance  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Traditional definitions of corporate governance are narrow, focusing on legal relations between managers and shareholders. More recent definitions extend the boundaries of governance to consider the role that various stakeholders play in shaping the behaviour of firms. While stakeholding theory embraces a broader set of corporate constituencies, our argument in this paper is that even these definitions are too narrow – they lack the analytical capacity to account for the social embeddedness...

Mason, Michael; O Mahony, Joan

2007-01-01

290

Post-traditional corporate governance  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Traditional definitions of corporate governance are narrow, focusing on legal relations between managers and shareholders. More recent definitions extend the boundaries of governance to consider the role that various stakeholders play in shaping the behaviour of firms. While stakeholder theory embraces a broader set of corporate constituencies, our argument in this paper is that even these definitions are too narrow—they lack the analytical capacity to account for the social embeddedness an...

Mason, Michael; O Mahony, Joan

2008-01-01

291

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.

292

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

293

Esoteric healing traditions: a conceptual overview.  

Science.gov (United States)

This paper presents, for the first time, a comprehensive scholarly examination of the history and principles of major traditions of esoteric healing. After a brief conceptual overview of esoteric religion and healing, summaries are provided of eight major esoteric traditions, including descriptions of beliefs and practices related to health, healing, and medicine. These include what are termed the kabbalistic tradition, the mystery school tradition, the gnostic tradition, the brotherhoods tradition, the Eastern mystical tradition, the Western mystical tradition, the shamanic tradition, and the new age tradition. Next, commonalities across these traditions are summarized with respect to beliefs and practices related to anatomy and physiology; nosology and etiology; pathophysiology; and therapeutic modalities. Finally, the implications of this survey of esoteric healing are discussed for clinicians, biomedical researchers, and medical educators. PMID:18316053

Levin, Jeff

2008-01-01

294

Acoustics of Chinese traditional theatres  

Science.gov (United States)

Chinese traditional theatre is unique in the world as an architectural form. The Chinese opera evolved into maturity as early as the Song and Yuan Dynasties, 11th-14th centuries, and Chinese theatrical buildings developed accordingly. As the Chinese opera plays on the principle of imaginary actions, no realistic stage settings are required. But Chinese audiences have placed great demands on vocal performance since ancient times. Pavilion stages that are small in area, open on three sides, and thrusting into the audience area are commonly found in traditional theatres, both the courtyard type and auditorium type. The pavilion stage is backed with a wall and a low ceiling (flat or domed). The stage functions as a reflecting shell, which enhances the sound to the audience and provides self-support to the singer. Numerous theatres of this kind exist and function in good condition to the present time. Acoustical measurements show that the sound strength and clarity in audience areas is satisfactory in moderate size courtyard traditional theatres. [Work supported by NSF.

Wang, J. Q.

2002-11-01

295

Insomnia in Iranian Traditional Medicine  

Science.gov (United States)

Context: Insomnia is one of the most prevalent sleep disorders characterized by sleep difficulty that impairs daily functioning and reduces quality of life. The burden of medical, psychiatric, interpersonal, and societal consequences of insomnia expresses the importance of diagnosing and treatment of insomnia. The aim of study was to investigate causes of insomnia from the viewpoint of Iranian traditional medicine. Evidence Acquisition: In this review study, we searched insomnia in a few of the most famous ancient textbooks of Iranian traditional medicine from different centuries. This books includeThe Canon of Medicine by Avicenna (the first version of Beirut), Zakhire Kharazmshahi by Jurjani (the scanned version of Bonyade Farhang-e Iran), Malfaregh by Razes (the first version of Iran University of Medical Sciences), and Aqili’s cure by Aqili (the first version of Iran University of Medical Sciences). Results: This study found that in Iranian traditional medicine manuscripts, insomnia was called sahar and even though many factors induce insomnia, most of them act through causing brain dystemperament. Conclusions: The brain dystemperament is considered one of the main causes of insomnia and insomnia can be well managed with an organized line of treatment, by correcting the brain dystemperament through elimination of causes. This study helps to find new solutions to treat insomnia. PMID:24829786

Feyzabadi, Zohre; Jafari, Farhad; Feizabadi, Parvin Sadat; Ashayeri, Hassan; Esfahani, Mohammad Mahdi; Badiee Aval, Shapour

2014-01-01

296

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

297

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

298

The Rao-Blackwellized Particle Filter: A Filter Bank Implementation  

Directory of Open Access Journals (Sweden)

Full Text Available 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 suitable for object-oriented programming. Our RBPF formulation can be seen as a Kalman filter bank with stochastic branching and pruning.

Karlsson Rickard

2010-01-01

299

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

300

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)

 
 
 
 
301

Stochastic stacking without filters  

International Nuclear Information System (INIS)

The rate of accumulation of antiprotons is a critical factor in the design of p anti p colliders. A design of a system to accumulate higher anti p fluxes is presented here which is an alternative to the schemes used at the CERN AA and in the Fermilab Tevatron I design. Contrary to these stacking schemes, which use a system of notch filters to protect the dense core of antiprotons from the high power of the stack tail stochastic cooling, an eddy current shutter is used to protect the core in the region of the stack tail cooling kicker. Without filters one can have larger cooling bandwidths, better mixing for stochastic cooling, and easier operational criteria for the power amplifiers. In the case considered here a flux of 1.4 x 108 per sec is achieved with a 4 to 8 GHz bandwidth

302

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

303

Filter Bank Fusion Frames  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

304

/C Microwave Filters  

Science.gov (United States)

The effects of temperature, illumination, and microwave signals on Ag/GaS0.5S0.5/C Schottky-type microwave filters have been investigated. The devices, which were produced from thin layers of GaSe0.5S0.5 single crystal, had room temperature barrier height and ideality factor of 0.65 eV and 3.28, respectively. Barrier height increased uniformly with increasing temperature, at 2.12 × 10-2 eV/K, and the ideality factor approached ideality. The devices can even function at 95°C. A current switching phenomenon from low to high injection ("On/Off") was also observed; this current switching appears at a particular voltage, V s, that shifts toward lower values as the temperature is increased. When the devices were reverse-biased and illuminated with a laser beam of wavelength 406 nm, a readily distinguishable V s was observed that shifted with increasing laser power. When the devices were run in passive mode and excited with an ac signal of power 0.0-20.0 dBm and frequency 0.05-3.0 GHz they behaved as band filters that reject signals at 1.69 GHz. Device resistance was more sensitive to signal amplitude at low frequencies (50 MHz) than at high frequencies. The features of these Ag/GaS0.5S0.5/C Schottky devices imply that they may be used as optical switches, as self standing, low band-pass, band reject filters, and as high band-pass microwave filters.

Qasrawi, A. F.; Khanfar, H. K.

2014-09-01

305

Regenerable particulate filter  

Science.gov (United States)

A method of making a three-dimensional lattice structure, such as a filter used to remove particulates from a gas stream, where the physical lattice structure is designed utilizing software simulation from pre-defined mass transfer and flow characteristics and the designed lattice structure is fabricated using a free-form fabrication manufacturing technique, where the periodic lattice structure is comprised of individual geometric elements.

Stuecker, John N. (Albuquerque, NM); Cesarano, III, Joseph (Albuquerque, NM); Miller, James E. (Albuquerque, NM)

2009-05-05

306

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

307

Carbon nanotube filters  

Science.gov (United States)

Over the past decade of nanotube research, a variety of organized nanotube architectures have been fabricated using chemical vapour deposition. The idea of using nanotube structures in separation technology has been proposed, but building macroscopic structures that have controlled geometric shapes, density and dimensions for specific applications still remains a challenge. Here we report the fabrication of freestanding monolithic uniform macroscopic hollow cylinders having radially aligned carbon nanotube walls, with diameters and lengths up to several centimetres. These cylindrical membranes are used as filters to demonstrate their utility in two important settings: the elimination of multiple components of heavy hydrocarbons from petroleum-a crucial step in post-distillation of crude oil-with a single-step filtering process, and the filtration of bacterial contaminants such as Escherichia coli or the nanometre-sized poliovirus (~25 nm) from water. These macro filters can be cleaned for repeated filtration through ultrasonication and autoclaving. The exceptional thermal and mechanical stability of nanotubes, and the high surface area, ease and cost-effective fabrication of the nanotube membranes may allow them to compete with ceramic- and polymer-based separation membranes used commercially.

Srivastava, A.; Srivastava, O. N.; Talapatra, S.; Vajtai, R.; Ajayan, P. M.

2004-09-01

308

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

309

Optimization of binary circular filters  

Science.gov (United States)

A rotation-invariant algorithm based on binary circular filters is developed for optical pattern recognition. The features of the genetic algorithm provide a highly efficient and rapid learning process. During training, the parameters of a circular filter are selected to maximize the distinction between the target and other expected objects in the image. These iteratively designed filters are good discriminators because they utilize all the spatial visual information about the target. Filters that optimize the trade-off between noise robustness and sharpness of the correlation peak can be determined. Binary circular filters when combined with spatial light modulators are appropriate for real-time applications.

Singher, Liviu; Ersoy, Okan K.; Miles, Gaines

1997-03-01

310

Optical filtering of aeromagnetic maps.  

Science.gov (United States)

An optical processor has been used to filter aeromagnetic contour maps in order to obtain information on underground magnetic ore deposits. This was accomplished by directional filtering of the spatial Fourier transform of the contour map. The directional filtering yields maps of gradients having given directions. A digital analysis was also performed on the data so that the feasibility of the optical technique could be evaluated. The results obtained so far suggest that a systematic filtering of aeromagnetic maps can be carried out at low cost and that the filtered maps can yield useful information to the interpreter. PMID:20126124

Arsenault, H H; Séguin, M K; Brousseau, N

1974-05-01

311

Theory and Applications of Kalman Filtering.  

Science.gov (United States)

Contents: Linear estimation theory; Further comments on the derivation of Kalman filters; Computational techniques in Kalman filtering; Modeling errors in Kalman filters; Suboptimal Kalman filter techniques; Comparison of Kalman, Bayesian and maximum like...

C. T. Leondes

1970-01-01

312

Filter for reactor emergency cooling system  

International Nuclear Information System (INIS)

The invention describes the design of a filter for the emergency cooling system. The new type of filter can be rinsed by flushing water backwards through the filter. The arrangement will prevent the filter from being silt up

313

Fuzzy Digital Filtering: Signal Interpretation  

Directory of Open Access Journals (Sweden)

Full Text Available The paper makes a description of the fuzzy filter properties considering its operational principles. A digital filter interacts with a reference model signal into real process in order to get the best corresponding answer, having the minimum error at the filter output using the mean square criterion. Adding into this filter structure a fuzzy mechanism, to obtain an intelligent filtering because adaptively select and emit a decision answer according with the external reference signal changes, in order to actualize the best correct new conditions updating a process dynamically. The interpretation of the input signal level describes the operation of the reference model, to update the filter weights giving the answers approximation in accordance with the reference signal in natural form. Finally the paper shows the simulations results of the fuzzy filter into the Kalman structure using the Matlab© tool.

Juan C. Sánchez García

2011-05-01

314

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

315

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

316

Alternatives to traditional complete dentures.  

Science.gov (United States)

Specific alternatives to traditional complete denture therapy have been controversial because of the uncertainties surrounding effectiveness of retention. This article addresses the importance of retention, border molding, diagnosis, and treatment planning, and the meticulous attention to detail required throughout the treatment course of these alternative modalities. Indications, advantages, and limitations are also presented. Although these alternatives are not routinely used in making complete dentures, they have been successfully used for the treatment of the edentulous patient. Alternatives serve as valuable prosthodontic treatment options that greatly enhance denture aesthetics, and should be considered for edentulous patients. PMID:24286647

Olvera, Norma; Jones, John D

2014-01-01

317

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

318

Fantastic filters of lattice implication algebras  

Directory of Open Access Journals (Sweden)

Full Text Available The notion of a fantastic filter in a lattice implication algebra is introduced, and the relations among filter, positive implicative filter, and fantastic filter are given. We investigate an equivalent condition for a filter to be fantastic, and state an extension property for fantastic filter.

Young Bae Jun

2000-08-01

319

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

320

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

 
 
 
 
321

Maneuvering target tracking using fuzzy logic-based recursive least squares filter  

Science.gov (United States)

In this paper, a fuzzy logic-based recursive least squares filter (FLRLSF) is presented for maneuvering target tracking (MTT) in situations of observations with unknown random characteristics. In the proposed filter, fuzzy logic is applied in the standard recursive least squares filter (RLSF) by the design of a set of fuzzy if-then rules. Given the observation residual and the heading change in the current prediction, these rules are used to determine the magnitude of the fading factor of RLSF. The proposed filter has an advantage in which the restrictive assumptions of statistical models for process noise, measurement noise, and motion models are relaxed. Moreover, it does not need a maneuver detector when tracking a maneuvering target. The performance of FLRLSF is evaluated by using a simulation and real test experiment, and it is found to be better than those of the traditional RLSF, the fuzzy adaptive ?-? filter (FA?-?F), and the hybrid Kalman filter in tracking accuracy.

Fan, En; Xie, Wei-xin; Liu, Zong-xiang

2014-12-01

322

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

323

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

324

Evaluation of high capacity filters  

International Nuclear Information System (INIS)

High capacity HEPA filters have the potential of significant savings in facilities and operating costs. By requiring fewer filters for a given air flow, the cost of a new plenum planned for construction at Rocky Flats could have been reduced by $8,000,000 if these high capacity filters were used. Also, by replacing the current 1000 cfm filters with these new filters in existing plenums, it was estimated that annual savings of about $1,000,000 in energy costs arising from the lowered pressure drop could be achieved. As a result, a program was initiated to determine whether high capacity filters could meet Rocky Flats qualifications imposed on filters used in plenums. Thus far twenty filters have been tested for filtration efficiencies and flow capacities. All had efficiencies which exceeded 99.97%. However, at 1'' w.g. their flow capacities were all below 2000 cfm. Seven filters have been subjected to the Heated Air Test. Of these, only 2 met the Rocky Flats requirement of less than 3% penetration. However the sealants for neither of these filters was self extinguishing as required

325

Adaptive scale-invariant filters  

Science.gov (United States)

Pattern recognition using a coherent optical correlator has many advantages, including high speed operation at almost the speed of light and the implementation of parallel processing. The key part of an optical correlator is the so-called optical filter. Properly designed filter should clearly indicate the presence of desired features in an image to be detected. Therefore,the performance of an optical system relies essentially upon the performance of the filter. Much research have been conducted to improve the performance of optical correlators. Most approaches to the filter design, however, fall short of providing robustness to minute changes in the image. In this paper a new approach to the adaptive design of optical filters, which are both shift- and scale-invariant, is proposed. The filters are constructed in real-time in an optical pattern recognition system by an adaptive, iterative numerical approach. The design is formalized as an optimization procedure, for which the filter performance is the function to be maximized. During the training procedure filter parameters are selected to maximize the distinction between the target and other objects in the image. The latter problem is solved using the genetic algorithm. Filters obtained in this optimization procedure are good discriminators since they utilize all the visual information about the target. Computer simulations demonstrate high discrimination of the designed filters.

Mirkin, Irina; Singher, Liviu

1997-10-01

326

Charcoal filter testing  

Energy Technology Data Exchange (ETDEWEB)

In this very brief, informal presentation, a representative of the US Nuclear Regulatory Commission outlines some problems with charcoal filter testing procedures and actions being taken to correct the problems. Two primary concerns are addressed: (1) the process to find the test method is confusing, and (2) the requirements of the reference test procedures result in condensation on the charcoal and causes the test to fail. To address these problems, emergency technical specifications were processed for three nuclear plants. A generic or an administrative letter is proposed as a more permanent solution. 1 fig.

Lyons, J. [Nuclear Regulatory Commission, Washington, DC (United States)

1997-08-01

327

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

328

Applied Filtered Density Function  

Directory of Open Access Journals (Sweden)

Full Text Available An overview is presented of recent advances in the filtered density function (FDF modeling and simulation of turbulent combustion. The review is focused on the developments that have facilitated the FDF to be broadly applied in large eddy simulation (LES of practical flows. These are primarily the development of a new Lagrangian Monte Carlo solver for the FDF, and the implementation of this solver on Eulerian domains portrayed by unstructured grids. With these developments, it is now much easier to apply FDF for predictions of reacting flows in complex geometrical configurations.

S.Levent Yilmaz

2013-01-01

329

A conservative nonlinear filter for the high-frequency range of wind wave spectra  

Science.gov (United States)

Filtering of the high-frequency part of a wind wave spectrum may be useful in a numerical wind wave model for various reasons. First, it can be used to augment (or be part of) a parameterization of the resonant nonlinear interactions, that are essential to third-generation wind wave models. Second, when combined with a dynamic time stepping scheme for source term integration, it may result in smoother (and hence faster) wave model integration. In this study, such a filter is proposed, based on the traditional Discrete Interaction Approximation (DIA) for the resonant four-wave nonlinear interactions. This filter retains all conservative properties of the interactions. For small time steps and/or smooth spectra, it is formulated as a traditional source term. For larger time steps and/or non-smooth spectra it is formulated as a filter. This formulation guarantees stability of the filter itself and will enhance overall computational stability in a full wave model. The stability properties of this filter are illustrated using traditional wave growth computations. Examples are given where the filter improves model economy, and where it is shown to remove spurious high-frequency noise from a wave model.

Tolman, Hendrik L.

330

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

331

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 10-9 at 0.1-?m particle diameter. In comparison, the present US nuclear filter certification test has a lower penetration limit of 10-5. 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 bag 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

332

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

333

Spatial filters for high average power lasers  

Science.gov (United States)

A spatial filter includes a first filter element and a second filter element overlapping with the first filter element. The first filter element includes a first pair of cylindrical lenses separated by a first distance. Each of the first pair of cylindrical lenses has a first focal length. The first filter element also includes a first slit filter positioned between the first pair of cylindrical lenses. The second filter element includes a second pair of cylindrical lenses separated by a second distance. Each of the second pair of cylindrical lenses has a second focal length. The second filter element also includes a second slit filter positioned between the second pair of cylindrical lenses.

Erlandson, Alvin C

2012-11-27

334

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

335

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

336

Anisotropic Total Variation Filtering  

International Nuclear Information System (INIS)

Total variation regularization and anisotropic filtering have been established as standard methods for image denoising because of their ability to detect and keep prominent edges in the data. Both methods, however, introduce artifacts: In the case of anisotropic filtering, the preservation of edges comes at the cost of the creation of additional structures out of noise; total variation regularization, on the other hand, suffers from the stair-casing effect, which leads to gradual contrast changes in homogeneous objects, especially near curved edges and corners. In order to circumvent these drawbacks, we propose to combine the two regularization techniques. To that end we replace the isotropic TV semi-norm by an anisotropic term that mirrors the directional structure of either the noisy original data or the smoothed image. We provide a detailed existence theory for our regularization method by using the concept of relaxation. The numerical examples concluding the paper show that the proposed introduction of an anisotropy to TV regularization indeed leads to improved denoising: the stair-casing effect is reduced while at the same time the creation of artifacts is suppressed.

337

Sodium aerosol removing filter  

International Nuclear Information System (INIS)

A sodium aerosol removing filter comprises a plurality of horizontal paths which are formed in the form of multiple steps in communication with each other and forming bending paths in a casing having an entrance formed on the lower side surface and an exit formed on the ceiling. Coarse metal meshes are disposed in horizontal paths situated upstream of the bending paths, intermediate metal meshes are disposed to horizontal paths at medium portion and a fine metal mesh is disposed to a horizontal path at downstream. If Na aerosol-containing air is charged from the entrance of the removing filter, the air successively passes through the horizontal paths which from the bending paths in the casing. Since the Na aerosol is captured in the metal meshes in the horizontal paths in the order of the greater grains as it flows, local clogging due to the capture is not caused, and a great amount of gas can be processed continuously for a long period of time. (T.M.)

338

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

339

Optimal Correlation Filters for Images with Signal-Dependent Noise  

Science.gov (United States)

We address the design of optimal correlation filters for pattern detection and recognition in the presence of signal-dependent image noise sources. The particular examples considered are film-grain noise and speckle. Two basic approaches are investigated: (1) deriving the optimal matched filters for the signal-dependent noise models and comparing their performances with those derived for traditional signal-independent noise models and (2) first nonlinearly transforming the signal-dependent noise to signal-independent noise followed by the use of a classical filter matched to the transformed signal. We present both theoretical and computer simulation results that demonstrate the generally superior performance of the second approach in terms of the correlation peak signal-to-noise ratio.

Downie, John D.; Walkup, John F.

1994-01-01

340

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

 
 
 
 
341

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

342

Faraday anomalous dispersion optical filters  

Science.gov (United States)

The effect of Faraday anomalous dispersion optical filters on infrared and blue transitions of some alkali atoms is calculated. A composite system is designed to further increase the background noise rejection. The measured results of the solar background rejection and image quality through the filter are presented. The results show that the filter may provide high transmission and high background noise rejection with excellent image quality.

Shay, T. M.; Yin, B.; Alvarez, L. S.

1993-01-01

343

Sample-whitened matched filters  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A sample-whitened matched filter (SWMF) for a channel with intersymbol interference and additive white Gaussian noise is defined as a linear filter with the properties that its output samples are a sufficient statistic for the MAP estimation of the transmitted sequence and have uncorrelated noise components. These filters are shown to exist for ali realistic channels and the complete set of SWMF's for any channel is determined. It is shown that for nonpathological channels there is a unique S...

Andersen, Ib

2010-01-01

344

Note: Cryogenic coaxial microwave filters  

International Nuclear Information System (INIS)

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

345

FILT - Filtering Indexed Lucene Triples  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Resource Description Framework (RDF) is the W3C recommended standard for data on the semantic web, while the SPARQL Protocol and RDF Query Language (SPARQL) is the query language that retrieves RDF triples by subject, predicate, or object. RDF data often contain valuable information that can only be queried through filter functions. The SPARQL query language for RDF can include filter clauses in order to define specific data criteria, such as full-text searches, numerical filtering, and c...

Stuhr, Magnus

2012-01-01

346

Tunable Imaging Filters in Astronomy  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

347

Semi-Hausdorff Fuzzy Filters  

Directory of Open Access Journals (Sweden)

Full Text Available The notion of fuzzy filters was studied by Vicente and Aranguren (1988, Lowen (1979, and Ramakrishnan and Nayagam (2002. The notion of fuzzily compactness was introduced and studied by Ramakrishnan and Nayagam (2002. In this paper, an equivalent condition of fuzzily compactness is studied and a new notion of semi-Hausdorffness on fuzzy filters, which cannot be defined in crisp theory of filters, is introduced and studied.

Geetha Sivaraman

2007-01-01

348

Efficient Feature Selection Methods in Chinese Spam Filtering  

Directory of Open Access Journals (Sweden)

Full Text Available This study, from the perspective of Chinese Spam Filtering, focuses on efficient feature selection methods. It expounds the traditional feature selection algorithms including Document Frequency (DF, Information Gain (IG, the Mutual Information (MI, Chi-square (CHI and Knowledge Gain (KG which is proposed in my previous study. Testing these methods on exposing Chinese spam data set, the results show that in Chinese spam corpus CHI and KG can efficiently extract valid features for spam classifications.

Xu Yan

2013-01-01

349

Estimation of aircraft aerodynamic derivatives using Extended Kalman Filter  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

350

Conditional Averaging a New Algorithm for Digital Filter  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper aims at designing a new algorithm for digital filters. The traditional methods like FIR, IIR have been improved in recent times with new approaches. However, the developments have used complex arithmetic calculation and dedicated DSP processors. In this research project, effort has been made to reduce such complexities using a procedure based on the technique of Conditional Averaging. The entire algorithm is developed using more of conditional statements and less of arithmetic calc...

Sukesh Rao, M.; S Narayana Iyer, Dr

2010-01-01

351

Comparison Types of Filter Used in Viewing Inner Structure of Materials Using X-Ray Computed Tomography  

International Nuclear Information System (INIS)

The inspection of inner structure of materials plays a very important role in safety and quality elements in industry. This process of inspection needs to be carried out in most accurate and efficient manner. Current practice, region of interest is normally being scanned directly to the radiation detector without filtering added. These procedures are assuming perfectly and accurately for the result image reconstruction without justification. While the process of inspection itself may generate unintentionally defects (artefacts). Besides, safety and quality, the use of several filtering techniques can overcome these deficiencies. X-ray computed tomography is a powerful non-invasive imaging technique for viewing an objects inner structures in 2-D or 3-D cross-section images without the need to physically section it. The invention of CT techniques revolutionised the field of medical diagnostic imaging because it provided more detailed and useful information than any previous non-invasive imaging techniques. The method is increasingly being used in industry, aerospace, geosciences and archaeology. This paper describes the comparison of filtering type (aluminium and copper) in X-ray computed tomography system for imaging and visualising of casting material (rear bracket engine mounting). The theoretical aspects of CT scanner, the system configurations and the adopted algorithm for image reconstruction are discussed. The penetrating rays from a 160 kV/10 mA industrial X-ray machine and a bank of Linear Array Detectors (LAD) in combination with a three-axis sample table were used to construct the CT system. The movement of the sample table in vertical, linear and rotary motion is controlled by a Lab View-based software, the x-ray transmission data is collected by using a commercial image grabber package, and the image reconstruction is performed by using the classical Linear Back Projection (LBP) algorithm. Sample of rear bracket engine mounting were scanned using this CT scanner with different type of filters. Some of the reconstructed images are presented in this paper. (author)

352

Optimal filters on the sphere  

CERN Document Server

We derive optimal filters on the sphere in the context of detecting compact objects embedded in a stochastic background process. The matched filter and the scale adaptive filter are derived on the sphere in the most general setting, allowing for directional template profiles and filters. The performance and relative merits of the two optimal filters are discussed. The application of optimal filter theory on the sphere to the detection of compact objects is demonstrated on simulated mock data. A naive detection strategy is adopted, with an initial aim of illustrating the application of the new optimal filters derived on the sphere. Nevertheless, this simple object detection strategy is demonstrated to perform well, even a low signal-to-noise ratio. Code written to compute optimal filters on the sphere (S2FIL), to perform fast directional filtering on the sphere (FastCSWT) and to construct the simulated mock data (COMB) are all made publicly available. (Accompanying code will be made publicly available on publi...

McEwen, J D; Lasenby, A N

2006-01-01

353

Optimization of integrated polarization filters  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 a...

Gagnon, Denis; Dumont, Joey; De?ziel, Jean-luc; Dube?, Louis J.

2014-01-01

354

Specific filter designs for PFBC  

Energy Technology Data Exchange (ETDEWEB)

Bubbling bed PFBC technology is currently being demonstrated at commercial scale. Economic and performance improvements in these first generation type PFBC plants can be realized with the application of hot gas particulate filters. Both the secondary cyclone(s) and stack gas ESP(s) could be eliminated saving costs and providing lower system pressure losses. The cleaner gas (basically ash free) provided with the hot gas filter, also permits a wider selection of gas turbines with potentially higher performance. For these bubbling bed PFBC applications, the hot gas filter must operate at temperatures of 1580{degree}F and system pressures of 175 psia (conditions typical of the Tidd PFBC plant). Inlet dust loadings to the filter are estimated to be about 500 to 1000 ppm with mass mean particle diameters ranging from 1.5 to 3 {mu}m. For commercial applications typical of the 70 MW{sub e} Tidd PFBC demonstration unit, the filter must treat up to 56,600 acfm of gas flow. Scaleup of this design to about 320 MW{sub e} would require filtering over 160,000 acfm gas flow. For these commercial scale systems, multiple filter vessels are required. Thus, the filter design should be modular for scaling. An alternative to the bubbling bed PFBC is the circulating bed concept. In this process the hot gas filter will in general be exposed to higher operating temperatures (1650{degree}F) and significantly higher (factor of 10 or more) particle loading.

Lippert, T.E.; Bruck, G.J.; Newby, R.A.; Smeltzer, E.E.

1993-09-01

355

Adaptive filtering and change detection  

CERN Document Server

Adaptive filtering is a branch of digital signal processing which enables the selective enhancement of desired elements of a signal and the reduction of undesired elements. Change detection is another kind of adaptive filtering for non-stationary signals, and is the basic tool in fault detection and diagnosis.This text takes the unique approach that change detection is a natural extension of adaptive filtering, and the broad coverage encompasses both the mathematical tools needed for adaptive filtering and change detection and the applications of the technology. Real engineering applicatio

Gustafsson, Fredrik

2003-01-01

356

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

357

China: Tradition, Nationalism and Just War.  

Science.gov (United States)

This paper examines Chinese culture and traditions to determine if there are concepts within the tradition corresponding to ideas of restraint as expounded in Western just war theories. In regards to jus ad bellum, Western ideas of sovereignty among equal...

T. E. Gong

1999-01-01

358

'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

359

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

360

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

 
 
 
 
361

Creating a Spam Filter  

Science.gov (United States)

This activity asks students to work in a team to develop a set of rules that can be used to program a SPAM filter for a client. The rules are based on characteristics of the subject lines of emails. Students are given samples of SPAM and non-SPAM subject lines to examine. After their rules are ready, they are given a test set of data to use and are asked to come up with a numerical measure to quantify how well their method (model) works. Each team writes a report describing how their model works and how well it performed on the test data. This activity could serve as an introduction to ideas of classification. Alternatively, the activity could be the basis for student introduction to types of statistical errors.

Minnesota., This P.

362

Human Rights and American Traditions  

Directory of Open Access Journals (Sweden)

Full Text Available Since the beginning, the United States has recognized and respected the rights of individuals. Besides serving as custodian of a rich historical and political tradition on human rights, the United States has contributed greatly to the crystallization of International human rights legislation through the establishment of the United Nations Organization and the development of the United Nations Charter. From my perspective, the real dilemma faced by the United States has included so far the issue of solving specific problems related to human rights, the way in which human rights considerations combine with other factors of foreign policy and the way of creating a sustainable public consensus in support of their policy on the realm of human rights. In my opinion it is unlikely that these efforts should ever be entirely solved successfully. That’s why, in this paper, I try to analyze the correlation between moral and pragmatic components of the U.S. policy on human rights in the last 40 years.

Alexandru Boboc-Cojocaru

2013-05-01

363

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

364

Mayo Clinic: Tradition and Heritage  

Science.gov (United States)

Heeding the words of their father, one Dr. W.W. Mayo, âÂÂNo one is big enough to be independent of othersâÂÂ, Dr. William J. Mayo and Dr. Charles H. Mayo helped create one of the worldâÂÂs first private integrated group practices of medicine. Now known as the Mayo Clinic, the story of their work is closely intertwined with the story of American medical history. As an attempt to bring this story to the web-browsing public, staff members at the Clinic recently created this historical timeline that offers some perspective on their institutional history. With their mouse in hand, visitors can move across the interactive timeline, which deploys high-quality photographs and short descriptions in its quest to document the ClinicâÂÂs various achievements, such as the creation of the first heart bypass machine in 1955. Finally, online visitors can get up close and personal to some of the artifacts that are close to the Mayo Clinic traditions, including a 1904 photograph of some of the medical staff at the Clinic.

2006-01-01

365

Abortion traditions in rural Jamaica.  

Science.gov (United States)

Abortion is not condoned in Jamaica. Its meaning is linked to the meanings of kinship and parenthood, which are expressed through procreation and involve altruism and the assumption of responsibility for the well-being of others. Abortion subverts these ideals but indigenous methods for it are known and are secretly used. The inconsistencies between abortion talk and abortion practice are examined, and the structural functions of abortion (and of its culturally constructed, ideological meaning) are discussed. The distinction--and the overlap--between abortion as such and menstrual regulation is explored. The use of the culturally constructed 'witchcraft baby' syndrome to justify abortion is also investigated. Traditional abortion techniques follow from (and can illuminate) general health practices, which focus on inducing the ejection of 'blockages' and toxins, and from ethnophysiological beliefs about procreation and reproductive health, which easily allow for menstrual delays not caused by conception. The latter understanding and the similarity between abortifacients, emmenagogues and general purgatives allows women flexibility in interpreting the meanings of their missed periods and the physical effects of the remedy. PMID:8643976

Sobo, E J

1996-02-01

366

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

367

Approximately Liner Phase IIR Digital Filter Banks  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, uniform and nonuniform digital filter banks based on approximately linear phase IIR filters and frequency response masking technique (FRM are presented. Both filter banks are realized as a connection of an interpolated half-band approximately linear phase IIR filter as a first stage of the FRM design and an appropriate number of masking filters. The masking filters are half-band IIR filters with an approximately linear phase. The resulting IIR filter banks are compared with linear-phase FIR filter banks exhibiting similar magnitude responses. The effects of coefficient quantization are analyzed.

J. D. ?erti?

2013-11-01

368

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)

369

Filter desulfation system and method  

Science.gov (United States)

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

370

The double well mass filter  

Science.gov (United States)

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; Rax, Jean-Marcel; Fisch, Nathaniel J.

2014-02-01

371

Directional Fuzzy Data Association Filter  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, a new multi-target tracking algorithm based on fuzzy logic for tracking in clutter is developed, it is called directional fuzzy data association (DFDA filter. The new algorithm incorporates the directional information of the targets for data association with the Mahalanobis distance. Firstly, the directional information, called pseudo-direction, is defined; the method of how to calculate the pseudo-direction has been introduced. Then the state incorporating with the pseudo-direction is updated using the cubature Kalman filter (CKF. At last the fuzzy logic inference method is used for data association. Simulation results are used to evaluate the performance of this new algorithm comparing with the nearest neighbor standard filter (NNSF and joint probability data association filter (JPDAF, the final results show that the proposed DFDA filter an efficient and effective approach for real application.

Pengfei Li

2012-10-01

372

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

373

Identification Filtering with fuzzy estimations  

Directory of Open Access Journals (Sweden)

Full Text Available A digital identification filter interacts with an output reference model signal known as a black-box output system. The identification technique commonly needs the transition and gain matrixes. Both estimation cases are based on mean square criterion obtaining of the minimum output error as the best estimation filtering. The evolution system represents adaptive properties that the identification mechanism includes considering the fuzzy logic strategies affecting in probability sense the evolution identification filter. The fuzzy estimation filter allows in two forms describing the transition and the gain matrixes applying actions that affect the identification structure. Basically, the adaptive criterion conforming the inference mechanisms set, the Knowledge and Rule bases, selecting the optimal coefficients in distribution form. This paper describes the fuzzy strategies applied to the Kalman filter transition function, and gain matrixes. The simulation results were developed using Matlab©.

J.J Medel J

2012-10-01

374

Constructing an optimal binary phase-only filter using a genetic algorithm  

Science.gov (United States)

A genetic algorithm is applied to the task of designing binary phase-only filters in a pattern recognition application. Binary phase-only filters have traditionally been using the classical matched filter as a baseline and then setting the magnitude portion of the filter to unity and binarizing the phase information. The resulting filter has much of its original information content, but is represented with a greatly reduced set of elements. Such filters have been shown to exceed the pattern recognition ability of the classical matched filter on which they are based. However, binary phase-only filters designed using this method are not optimal for discrimination or invariance to pattern changes and several different researchers have investigated various optimization techniques. This paper describes a new technique for designing binary phase-only filters using a genetic algorithm. A population of filters is initially constructed with random phase elements and then modified by the genetic algorithm to produce successively better filters. Each member of the population consists of two chromosomes which contain the genetic information coding for a paid of discrimination filters. During each generation of the algorithm, a new population is produced from the previous population by applying a set of four operators. The four operators include a stochastic remainder selection operator, a two-dimensional crossover operator, a mutation operator, and a survival operator. The fitness function used in the selection and survival operators is based on the ability of the two binary phase-only filters represented by an individual's chromosomes to discriminate between two different classes of characters.

Calloway, David L.

1991-11-01

375

Deconvolution filtering: temporal smoothing revisited.  

Science.gov (United States)

Inferences made from analysis of BOLD data regarding neural processes are potentially confounded by multiple competing sources: cardiac and respiratory signals, thermal effects, scanner drift, and motion-induced signal intensity changes. To address this problem, we propose deconvolution filtering, a process of systematically deconvolving and reconvolving the BOLD signal via the hemodynamic response function such that the resultant signal is composed of maximally likely neural and neurovascular signals. To test the validity of this approach, we compared the accuracy of BOLD signal variants (i.e., unfiltered, deconvolution filtered, band-pass filtered, and optimized band-pass filtered BOLD signals) in identifying useful properties of highly confounded, simulated BOLD data: (1) reconstructing the true, unconfounded BOLD signal, (2) correlation with the true, unconfounded BOLD signal, and (3) reconstructing the true functional connectivity of a three-node neural system. We also tested this approach by detecting task activation in BOLD data recorded from healthy adolescent girls (control) during an emotion processing task. Results for the estimation of functional connectivity of simulated BOLD data demonstrated that analysis (via standard estimation methods) using deconvolution filtered BOLD data achieved superior performance to analysis performed using unfiltered BOLD data and was statistically similar to well-tuned band-pass filtered BOLD data. Contrary to band-pass filtering, however, deconvolution filtering is built upon physiological arguments and has the potential, at low TR, to match the performance of an optimal band-pass filter. The results from task estimation on real BOLD data suggest that deconvolution filtering provides superior or equivalent detection of task activations relative to comparable analyses on unfiltered signals and also provides decreased variance over the estimate. In turn, these results suggest that standard preprocessing of the BOLD signal ignores significant sources of noise that can be effectively removed without damaging the underlying signal. PMID:24768215

Bush, Keith; Cisler, Josh

2014-07-01

376

Central difference predictive filter for attitude determination with low precision sensors and model errors  

Science.gov (United States)

Attitude determination is one of the key technologies for Attitude Determination and Control System (ADCS) of a satellite. However, serious model errors may exist which will affect the estimation accuracy of ACDS, especially for a small satellite with low precision sensors. In this paper, a central difference predictive filter (CDPF) is proposed for attitude determination of small satellites with model errors and low precision sensors. The new filter is proposed by introducing the Stirling's polynomial interpolation formula to extend the traditional predictive filter (PF). It is shown that the proposed filter has higher accuracy for the estimation of system states than the traditional PF. It is known that the unscented Kalman filter (UKF) has also been used in the ADCS of small satellites with low precision sensors. In order to evaluate the performance of the proposed filter, the UKF is also employed to compare it with the CDPF. Numerical simulations show that the proposed CDPF is more effective and robust in dealing with model errors and low precision sensors compared with the UKF or traditional PF.

Cao, Lu; Chen, Xiaoqian; Misra, Arun K.

2014-12-01

377

NIOSH-Approved Particulate Filtering Facepiece Respirators  

Science.gov (United States)

... List of Approved Filtering Facepiece Respirators Other Important Filtering Facepiece Respirator Information Section 1: NIOSH-Approved Respirators - ... Program FAQs Additional Respiratory Protection Resources Approved ... Filtering Facepiece Respirators Certified Equipment List (CEL) Respirator User ...

378

Shunt Active Filter in Damping Harmonics Propagation  

Directory of Open Access Journals (Sweden)

Full Text Available This paper deals with a hybrid shunt active power filter applied on 500 kV HVDC, after a description of the causes and effects harmonic pollution which may damage equipments and interrupt electric power customers service; in this paper we present the deferent solutions of this problem among one has to study the two most recent types of filtering: passive and hybrid filter. The hybrid filter consists of active filter connected in shunt with passive filter. The hybrid shunt active filter proposed is based on three levels PWM inverter and characterized by detecting the harmonic current flowing into the passive filter and controlled by notch algorithm. This structure has been applied on a test HVDC power system, is presented as a technical solution makes it possible to eliminate the disadvantages from passive filtering, and also economic price of active filtering part. The simulation results justified the effectiveness of this type of filter face of the classic passive filter.

BERBAOUI, B.

2010-08-01

379

Comparative Study of Target Function Definition in Linear Phase FIR Filter Design  

Directory of Open Access Journals (Sweden)

Full Text Available The Weighted Least Squares (WLS principle is popular in filter design due to its flexibility, where it can output equiripple filters with appropriate target function and weighted function. Therefore, this research studies the influence of the target function in linear phase Finite-Impulse-Response (FIR filter design by comparing different target functions in WLS iterations. Compared with the traditional one, simulations show that the proposed target function can obtain more accurate stopband start frequencies which will be useful if the stopband start frequency must be precise in applications.

Chengfeng Ruan

2012-01-01

380

Reduction of Data Sparsity in Collaborative Filtering based on Fuzzy Inference Rules  

Directory of Open Access Journals (Sweden)

Full Text Available Collaborative filtering Recommender system plays avery demanding and significance role in this era ofinternet informationand of course e commerce age.Collaborative filtering predicts user preferencesfrom past user behaviouror user-item relationships.Though it has many advantages it also has somelimitations such as sparsity, scalability, accuracy,cold start problem etc.In this paper we proposed amethod that helps in reducing sparsity to enhancerecommendation accuracy. We developed fuzzyinference ruleswhich is easily to implement andalso gives better result. Acomparison experiment isalsoperformingwith two previous methods,Traditional Collaborative Filtering (TCF andHybrid User Model Technique (HUMCF.

A tisha Sachan

2013-06-01

 
 
 
 
381

Silver as a soft x-ray filter for plasma diagnostics  

International Nuclear Information System (INIS)

Silver is shown to be a superior light blocking soft x-ray filter in low-temperature plasma diagnostics. Compared with traditional material like aluminium, it has excellent rejection at VUV wavelength while providing a superior transmission window between 3.2 and 10 nm. It has been used to measure the electron temperature of a laser-initiated gas-embedded Z-pinch using the multiple-filter ratio method. Using a combination of silver and aluminium coated plastic filters, it is shown that the ratio method can be extended to measure temperatures down to 30 eV with good accuracy. (author)

382

Improving GPS Precision and Processing Time using Parallel and Reduced-Length Wiener Filters  

CERN Document Server

Increasing GPS precision at low cost has always been a challenge for the manufacturers of the GPS receivers. This paper proposes the use of a Wiener filter for increasing precision in substitution of traditional GPS/INS fusion systems, which require expensive inertial systems. In this paper, we first implement and compare three GPS signal processing schemes: a Kalman filter, a neural network and a Wiener filter and compare them in terms of precision and the processing time. To further reduce the processing time of Wiener filter, we propose parallel and reduced-length implementations. Finally, we calculate the sampling frequency that would be required in every Wiener scheme in order to obtain the same total processing time as the Kalman filter and the neural network.

Garcia, J

2010-01-01

383

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

384

Filter for radioactive iodine  

International Nuclear Information System (INIS)

Purpose: To prevent the reduction in the activity of radioactive iodine adsorbent material at high temperature. Constitution: Regenerated cellulose type fiberous activated carbon with the pore volume of 0.08 cc/g is reactivated by impregnating to support 10% by weight of magnesium acetate to obtain fiberous activated carbon with the pore volume 0.40 cc/g for the pores having diameter between 30 - 300 A. 60 parts of the activated carbon, 40 parts of breaching graft pulp made of coniferous trees and 7 parts by weight of polyvinyl alcohol fibers are subjected to a paper- making process to obtain activated carbon paper. Then, it is molded into a single side corrugated sheet, which is immersed in an ethanol solution containing 20% by weight of triethylenediamine then dried and molded into a honeycomb filter. It is necessary that the activated carbon material has pore volume of more than 5 cc/g for the pores having diameter between 30 - 300 A. (Horiuchi, T.)

385

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

386

Large array VLSI filter  

Science.gov (United States)

A 35 by 35 element pipelined convolutional kernel is being fabricated using VLSI chips, each containing a 5 by 1 segment of the kernel. Three levels of printed circuitry are used: the first level is used for the VLSI chips, the second level connects seven chips together on one platform, and the third level connects seven platforms with associated delay lines, all fitting on one board. Therefore, on each board there are seven rows of the kernel containing 245 multipliers and adders, and five such boards complete the kernel array. Each multiplier accepts an 8 bit picture element which is multiplied by a 16 bit weight. A truncated 22 bit product is added to a previously stored product sum and the results are shifted to the following multiplier as the next picture element is read in. The multiplier uses a modified Booth algorithm to reduce the number of shift add operations nearly in half. The filter box is presently configured as an ancillary box to a VAX 11/780, but can be connected to essentially any CPU. The I/O bandwidth is easily compatible with most CPU devices.

Nathan, R.

1983-01-01

387

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

388

Paediatric cardiac CT examinations: impact of the iterative reconstruction method ASIR on image quality - preliminary findings  

International Nuclear Information System (INIS)

filtered back-projection method. Reconstruction including 20% to 40% ASIR slightly improved the conspicuity of various paediatric cardiac structures in newborns and children with respect to conventional reconstruction (filtered back-projection) alone. (orig.)

389

MATLAB Based Digital IIR Filter Design  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

Samarjeet Singh; Uma Sharma

2012-01-01

390

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

391

A Gaussian mixture ensemble transform filter  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

392

Image Edges Strengthening Filter Based Color Filter Array Interpolation  

Directory of Open Access Journals (Sweden)

Full Text Available Most of the digital cameras use color filter arrays instead of beam splitters to capture image data so as to reduce the cost and to gain more efficiency. As a result of this, only one of the required three color samples becomes available at each pixel location and the other two needs to be interpolated. This procedure is called Color Filter Array (CFA interpolation or demosaicing. So as to improve subjective and objective interpolation quality many demosaicing algorithms have been introduced. We propose an orientation-free edge strength filter and apply it to the demosaicing problem. Output of edge strength filter is utilized both to improve the initial green channel interpolation and to apply the constant color difference rule adaptively. This simple edge method yields visually pleasing results with high CPSNR.

C Mohammed Abdul Malik#1, B.N.Nagaveni

2013-09-01

393

Color Filter Array Interpolation for Edge Strength Filters  

Directory of Open Access Journals (Sweden)

Full Text Available Basically we use beam splitters to capture data or image. Using beam splitters is very expensive, so inorder to overcome this we go for an alternative technique called color filters arrays. As a result of this, only one of the required three color samples becomes available at each pixel location and the other two need to be interpolated. This process is called Color Filter Array (CFA interpolation or demosaicing. Many demosaicing algorithms have been introduced over the years to improve subjective and objective interpolation quality. Wepropose an orientation-free edge strength filter and apply it to the demosaicing problem. Edge strength filter output is utilized both to improve the initial green channel interpolation and to apply the constant color difference rule adaptively. This simple edge directed method yields visually pleasing results with high CPSNR.

L.Naveen#1, B.Shobanbabu*2, M.Tech (Ph????. ?d?

2013-07-01

394

Pragmatic circuits signals and filters  

CERN Document Server

Pragmatic Circuits: Signals and Filters is built around the processing of signals. Topics include spectra, a short introduction to the Fourier series, design of filters, and the properties of the Fourier transform. The focus is on signals rather than power. But the treatment is still pragmatic. For example, the author accepts the work of Butterworth and uses his results to design filters in a fairly methodical fashion. This third of three volumes finishes with a look at spectra by showing how to get a spectrum even if a signal is not periodic. The Fourier transform provides a way of dealing wi

Eccles, William

2006-01-01

395

Adaptive filters theory and applications  

CERN Document Server

This second edition of Adaptive Filters: Theory and Applications has been updated throughout to reflect the latest developments in this field; notably an increased coverage given to the practical applications of the theory to illustrate the much broader range of adaptive filters applications developed in recent years. The book offers an easy to understand approach to the theory and application of adaptive filters by clearly illustrating how the theory explained in the early chapters of the book is modified for the various applications discussed in detail in later chapters. This integ

Farhang-Boroujeny, Behrouz

2013-01-01

396

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

397

Attitude Representations for Kalman Filtering  

Science.gov (United States)

The four-component quaternion has the lowest dimensionality possible for a globally nonsingular attitude representation, it represents the attitude matrix as a homogeneous quadratic function, and its dynamic propagation equation is bilinear in the quaternion and the angular velocity. The quaternion is required to obey a unit norm constraint, though, so Kalman filters often employ a quaternion for the global attitude estimate and a three-component representation for small errors about the estimate. We consider these mixed attitude representations for both a first-order Extended Kalman filter and a second-order filter, as well for quaternion-norm-preserving attitude propagation.

Markley, F. Landis; Bauer, Frank H. (Technical Monitor)

2001-01-01

398

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

399

Filtering electrocardiogram signals using the extended Kalman filter.  

Science.gov (United States)

In this paper the Extended Kalman Filter (EKF) has been used for the filtering of Electrocardiogram (ECG) signals. The method is based on a previously nonlinear dynamic model proposed for the generation of synthetic ECG signals. The results show that the EKF may be used as a powerful tool for the extraction of ECG signals from noisy measurements; which is the state of the art in applications such as the noninvasive extraction of fetal cardiac signals from maternal abdominal signals. PMID:17281535

Sameni, R; Shamsollahi, M B; Jutten, C

2005-01-01

400

Filtering Electrocardiogram Signals Using the Extended Kalman Filter  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper the Extended Kalman Filter (EKF) has been used for the filtering of Electrocardiogram (ECG) signals. The method is based on a previously nonlinear dynamic model proposed for the generation of synthetic ECG signals. The results show that the EKF may be used as a powerful tool for the extraction of ECG signals from noisy measurements; which is the state of the art in applications such as the noninvasive extraction of fetal cardiac signals from maternal abdominal signals.

Sameni, Reza; Shamsollahi, M. B.; Jutten, Christian

2006-01-01

 
 
 
 
401

Traditional marketing vs. Internet marketing. A comparison  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Title: Traditional marketing vs. Internet marketing: A comparison Problem: Marketing is an important strategy for businesses and it contains numerous effective tools. Traditional marketing has been in use for many years and nowadays Internet has brought new ways of doing business for companies and that has affected marketing. What are the main differences between Internet marketing and traditional marketing? Which one of the two approaches contains the most used and effective marketing tools ...

Varfan, Mona; Shima, Alfa

2008-01-01

402

Audio Thumbnail Generation of Irish Traditional Music  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An approach is presented which generates an audio thumbnail of Irish traditional music. An audio thumbnail is consered to be the most representative segment of the music. For popular music, the chorus is considered to be an ideal audio thumbnail, however in Irish Traditional Music there is no chorus. An Irish Traditional tune consists of tow or mor short structural segments called parts. Parts are repeated to extend the tuen, and the tune itself is also repeated once or more in its entirety. ...

Kelly, Cillian; Gainza, Mikel; Dorran, David; Coyle, Eugene

2010-01-01

403

Aboriginal Oral Traditions of Australian Impact Craters  

CERN Document Server

We explore Aboriginal oral traditions that relate to Australian meteorite craters. Using the literature, first-hand ethnographic records, and fieldtrip data, we identify oral traditions and artworks associated with four impact sites: Gosses Bluff, Henbury, Liverpool, and Wolfe Creek. Oral traditions describe impact origins for Gosses Bluff and Wolfe Creek craters and non-impact origins of Liverpool and Henbury craters, with Wolfe Creek stories having both impact and non-impact origins. Three impact sites that are believed to have formed during human habitation of Australia - Dalgaranga, Veevers, and Boxhole - do not have associated oral traditions that are reported in the literature.

Hamacher, Duane W

2013-01-01

404

Polarization filtering of SAR data  

Science.gov (United States)

In this paper, a systematic theoretical analysis of polarization filtering for a bistatic system is developed for two applications: maximization of signal to noise ratio and discrimination between two target types. The described method finds the optimum receive antenna polarization analytically but relies on a numerical approach to find the optimum transmit antenna polarization. The method uses the Stokes matrix representation, and therefore applies to analyze the partially polarized scattered field from extended targets. Examples of the technique are presented for the NASA CV990 polarimetric L-band radar. Image enhancement filters maximizing the signal-to-noise ratio are developed for different noise characteristics and different target types (urban and forest). A filter is also developed to maximize the power ratio between urban and natural targets. Results show that the filter maximizing the contrast between urban and forest area is essentially the same as the one maximizing the contrast between urban and ocean areas.

Dubois, Pascale; van Zyl, Jakob J.

1993-02-01

405

Dimensional reduction in nonlinear filtering  

International Nuclear Information System (INIS)

The theory of nonlinear filtering forms the framework of many data assimilation problems. When the rates of change of different variables differ by orders of magnitude, efficient data assimilation can be accomplished by constructing nonlinear filtering equations for the coarse-grained signal. We consider the conditional law of a signal given the observations in a multi-scale context. In particular, we study how scaling interacts with filtering via stochastic averaging. This is an extension of our previous work (Park et al 2008 Stoch. Dyn. 8 543–60) where the observation process depended only on the fast variable, so the filter became independent of the observation in the limit. Here, we investigate a more realistic setting in which the observation depends on both the slow and the fast variables

406

Thermally tunable optical filter array  

Science.gov (United States)

A novel MEMS-based tunable optical filter, an essential component for monitoring and reconfiguration of optical wavelength-division multiplexing networks, is presented. The device is based on a Fabry-Perot interferometer employing multiple solid-state silicon cavities and silicon-based dielectric Bragg mirrors. Tuning is achieved through thermal modulation of the resonator's optical thickness. It is fabricated as a free-standing membrane using silicon MEMS technology. The filter membrane is fixed by micromachined suspension arms, which thermally isolates it against the substrate. The present concept features low power consumption and fast thermal modulation. Light coupling to the filter array is realized by positioning of fibers and the filter chip in a micro-optical bench setup.

Hohlfeld, Dennis; Epmeier, Matthias; Zappe, Hans P.

2003-06-01

407

Angular device for optical filters  

Science.gov (United States)

Device provides a means for precise angular adjustment of optical filters in Raman calibration detector units. Device prevents stray light from entering system and has the capability of repeated alignments to predetermined angles.

Overbay, L. W.

1975-01-01

408

Design of Narrow Band FIR Filters  

Directory of Open Access Journals (Sweden)

Full Text Available A new concept for the design of finite impulse response (FIR filters is introduced here. This analytical approach has led to three fundamental and new results. First, a differential equation for the approximating polynomial of the filter is developed. Second, the linear differential equation is solved by iteration, yielding an algorithm for recursive evaluation of the impulse response of a filter. Finally, the degree equation of the filter is introduced. We present the design of 4 types of narrow band FIR filters: the maximally at notch FIR filter, the equiripple notch FIR filter, the equiripple DC-notch FIR filter and the equiripple comb FIR filter. Equiripple filters are optimal in the Chebyshev sense. The design procedure starts with frequency specifications of the filter and ends with a recursive evaluation of the impulse response coefficients refraining from other numerical procedures.

Miroslav Vlcek and Pavel Zahradnik

2008-05-01

409

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

410

Lead encephalopathy due to traditional medicines.  

Science.gov (United States)

Traditional medicine use is common in developing countries and increasingly popular in the western world. Despite the popularity of traditional medicines, scientific research on safety and efficacy is limited. However documented fatalities and severe illness due to lead poisoning are increasingly recognized to be associated with traditional medicine use. As society becomes more globalized, it is imperative for pharmacists and health care providers to learn about the safety of traditional medical practices. The information presented educates and alerts pharmacists and health care providers about the potential of traditional medicines to cause lead encephalopathy. Case reports were located through systematic literature searches using MEDLINE, CINAHL, AMED, CISCOM, EMBASE and The Cochrane library from 1966 to the February 2007. Reference lists of identified articles and the authors' own files were also searched. Inclusion criteria were cases of human lead encephalopathy associated with traditional medical practices. There were no restrictions regarding the language of publication. Data were subsequently extracted and summarized in narrative and tabular form. We found 76 cases of lead encephalopathy potentially associated with traditional medicine. Ayurvedic medicines were associated with 5 cases (7%), Middle eastern traditional medicines with 66 cases (87%) and 5 cases (7%) with other traditional medicines. Of the 76 cases, 5% were in adults and 95% were in infants and young children. Of the 4 adult cases, at least one was left with residual neurological impairment. In infants and young children, among 72 cases 8 (11%) were fatal, and at least 15 (21%) had residual neurological deficits. Traditional medicine users should be screened for lead exposure and strongly encouraged to discontinue metal-containing remedies. Therefore, the United States Food and Drug Administration and corresponding agencies in other countries should require and enforce heavy metal testing for all imported traditional medicines and "dietary supplements". PMID:18690981

Karri, Surya K; Saper, Robert B; Kales, Stefanos N

2008-01-01

411

Spin Filtering in Storage Rings  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The spin filtering in storage rings is based on the multiple passage of a stored beam through a polarized internal gas target. Apart from the polarization by transmission, a unique geometrical feature of interaction with the target in such a filtering process, pointed out by H.O. Meyer \\cite{Meyer}, is a scattering of stored particles within the beam. A rotation of the spin in the scattering process affects the polarization buildup. We derive here a quantum-mechanical evolut...

Nikolaev, N. N.; Pavlov, F. F.

2005-01-01

412

Velocity filter for charged particles  

International Nuclear Information System (INIS)

In a number of studies of the energy spectrum of charged-particles beams, it is necessary to eliminate the contribution of parasitic particles, the spectrum of which immediately adjoins the spectrum of useful particles. Such suppression can be accomplished by means of a velocity filter which transmits all particles with energy above (or below) some fixed energy. The possibility of using a cylindrical electrostatic mirror as such a filter is discussed

413

Filter indexing for spectrophotometer system  

International Nuclear Information System (INIS)

A spectrophotometer system has an optical system for transmitting a beam from a source at select wavelengths onto a detector. A plurality of filters are positioned in a tray. A stepper mechanism indexes the tray along a path. A microcomputer controls the stepper mechanism and the optical system. The wavelength is successively changed over a range, the tray is indexed to move a select filter into the beam at a predetermined wavelength and the changing is discontinued during indexing

414

Self-tuning bandpass filter  

Science.gov (United States)

An electronic filter is described which simultaneously maintains a constant bandwidth and a constant center frequency gain as the input signal frequency varies, and remains self-tuning to that center frequency over a decade range. The filter utilizes a field effect transistor (FET) as a voltage variable resistance in the bandpass frequency determining circuit. The FET is responsive to a phase detector to achieve self-tuning.

Deboo, G. J.; Hedlund, R. C. (inventors)

1973-01-01

415

Superconductive Coplanar-Waveguide Filters  

Science.gov (United States)

Coplanar-waveguide microwave low-pass filters based on thin films of high-critical-temperature superconductor YBa2Cu3O7 built and tested. Designed to provide passband of 0 to 9.5 GHz. Dimensions suitable for microwave integrated circuits and chosen to provide fairly stringent test of usefulness and practicality of design and of method of fabrication. Insertion loss less than filter made with copper.

Chew, Wilbert; Bajuk, Louis J.; Cooley, Thomas W.; Foote, Marc C.; Hunt, Brian D.; Rascoe, Daniel L.; Riley, Abraham L.

1992-01-01

416

Greenfield filters in pulmonary embolism  

International Nuclear Information System (INIS)

Pulmonary embolism remains one of the most important causes of sudden hospital deaths. From January 1982 to December 1985 24 Greenfield filters were inserted for the treatment of recurrent pulmonary embolism. Only 1 patient had a possible recurrent pulmonary embolus and 1 patient had angulation and penetration of the vein wall. Radionuclide venography demonstrated that all inferior venae cavae were patent. The mortality rate of 38% was not related to the Greenfield filter

417

Narrow-Band Microwave Filters  

Directory of Open Access Journals (Sweden)

Full Text Available Original design of the narrow-band compact filters based on the high-quality waveguide-dielectric resonator with anisotropic materials has been presented in this work. Designed filters satisfy the contradictory requirements: they provide the narrow frequency band (0.05 ÷ 0.1 % of the main frequency f0 and the low initial losses ?0 ? 1 dB.

A.V. Strizhachenko

2010-01-01

418

The Kalman-Levy filter  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Kalman filter combines forecasts and new observations to obtain an estimation which is optimal in the sense of a minimum average quadratic error. The Kalman filter has two main restrictions: (i) the dynamical system is assumed linear and (ii) forecasting errors and observational noises are taken Gaussian. Here, we offer an important generalization to the case where errors and noises have heavy tail distributions such as power laws and L\\'evy laws. The main tool needed to...

Sornette, D.; Ide, K.

2000-01-01

419

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