This talk will describe computed tomography (CT) reconstruction using filtered back-projection on SPRINT parallel computers. CT is a computationally intensive task, typically requiring several minutes to reconstruct a 512x512 image. SPRINT and other parallel computers can be applied to CT reconstruction to reduce computation time from minutes to seconds. SPRINT is a family of massively parallel computers developed at LLNL. SPRINT-2.5 is a 128-node multiprocessor whose performance can exceed twice that of a Cray-Y/MP. SPRINT-3 will be 10 times faster. Described will be the parallel algorithms for filtered back-projection and their execution on SPRINT parallel computers.

A three-dimensional filtering engine, a convolution engine, and a back projection engine were developed for real-time signal processing of three-dimensional computed tomography. The performance of the system was measured and through-put of 0.5 second per one cross sectional data processing was attained. (author)

Purpose Reconstruction of DaTSCAN brain studies using OS-EM iterative reconstruction offers better image quality and more accurate quantification than filtered back-projection. However, reconstruction must proceed for a sufficient number of iterations to achieve stable and accurate data. This study assessed the impact of the number of iterations on the image quantification, comparing the results of the iterative reconstruction with filtered back-projection data. Methods A striatal phantom filled with 123I using striatal to background ratios between 2:1 and 10:1 was imaged on five different gamma camera systems. Data from each system were reconstructed using OS-EM (which included depth-independent resolution recovery) with various combinations of iterations and subsets to achieve up to 200 ...

A novel time-domain spectroscopic EPR imaging approach, that is a unique combination of already known techniques, is described. The first one is multi-gradient Single Point Imaging involving pure phase-encoding where the oximetry is based on Formula Not Shown . Line width derived from Formula Not Shown is subject to susceptibility effects and therefore needs system-dependent line width calibrations. The second approach utilizes the conventional 90degree-t-180degree Spin-Echo pulse sequence where the images are obtained by the filtered back-projection after FT of the echoes collected under frequency-encoding gradients. The spatially resolved oximetry information is derived from a set of T2-weighted images. The back-projection images suffer susceptibility artifacts with resolution determined...

The objective of this work is to perform a Monte Carlo simulation with GATE software tool of a realistic numerical phantom of a real patient. Results from the simulation, in terms of simulated decays, recorded coincidences and simulation time, are presented. Output data are reconstructed using the Software for Tomographic Image Reconstruction (STIR) package. Two different STIR image reconstruction algorithms are used to perform the reconstruction-Filtered Back Projection/3DRP and Ordered Subset Maximum A Posteriori One-Step Late algorithms. Reconstructed images are also presented.

The scattering noise artifact resulted in low-dose projection in repetitive cone-beam CT (CBCT) scans decreases the image quality and lessens the accuracy of the diagnosis. To improve the image quality of low-dose CT imaging, the statistical filtering is more effective in noise reduction. However, image filtering and enhancement during the entire reconstruction process exactly may be challenging due to high performance computing. The general reconstruction algorithm for CBCT data is the filtered back-projection, which for a volume of 512×512×512 takes up to a few minutes on a standard system. To speed up reconstruction, massively parallel architecture of current graphical processing unit (GPU) is a platform suitable for acceleration of mathematical calculation. In this paper, we focus on accelerating wavelet denoising and Feldkamp-Davis-Kress (FDK) back-projection using parallel processing on GPU, utilize compute unified device architecture (CUDA) platform and implement CBCT reconstruction based on CUDA technique. Finally, we evaluate our implementation on clinical tooth data sets. Resulting implementation of wavelet denoising is able to process a 1024×1024 image within 2 ms, except data loading process, and our GPU-based CBCT implementation reconstructs a 512×512×512 volume from 400 projection data in less than 1 minute.

Several factors during the scanning process, image reconstruction and geometry of an imaging system, influence the spatial resolution of a computed tomography imaging system. In this work, the spatial resolution of a state of the art flat panel detector-based cone beam computed tomography breast imaging system is evaluated. First, scattering, exposure level, voltage, voxel size, pixel size, back-projection filter, reconstruction algorithm, and number of projections are varied to evaluate their effect on spatial resolution. Second, its uniformity throughout the whole field of view is evaluated as a function of radius along the x-y plane and as a function of z at the center of rotation. The results of the study suggest that the modulation transfer function is mainly influenced by the pixel, back-projection filter, and number of projections used. The evaluation of spatial resolution throughout the field of view also suggests that this imaging system does have a 3-D quasi-isotropic spatial resolution in a cylindrical region of radius equal to 40 mm centered at the axis of rotation. Overall, this study provides a useful tool to determine the optimal parameters for the best possible use of this cone beam computed tomography breast imaging system.

Objectives: To assess the effects of image reconstruction method on hepatic CT perfusion (CTP) values using two CT protocols with different radiation doses. Materials and methods: Sixty patients underwent hepatic CTP and were randomly divided into two groups. Tube currents of 210 or 250mA were used for the standard dose group and 120 or 140mA for the low dose group. The higher currents were selected for large patients. Demographic features of the groups were compared. CT images were reconstructed by using filtered back projection (FBP), image filter (quantum de-noising, QDS), and adaptive iterative dose reduction (AIDR). Hepatic arterial and portal perfusion (HAP and HPP, ml/min/100ml) and arterial perfusion fraction (APF, %) were calculated using the dual-input maximum slope method. ROIs ...

Compared to traditional L filter, a LCL filter is more effective on reducing harmonic distortion at switch frequency. So it is important to choose the LCL filter parameters to achieve good filtering effect. This paper introduces some traditional design methods. Design of a LCL filter by genetic algorithm (GA) and particle swam optimization (PSO) are presented in this paper and comparison of the two intelligent optimization. Simulation result and calculate data are provided to prove that intelligent optimization are more effective and simple than traditional methods.

Three algorithms for breast tomosynthesis reconstruction were compared in this paper, including (1) a back-projection (BP) algorithm (equivalent to the shift-and-add algorithm), (2) a Feldkamp filtered back-projection (FBP) algorithm, and (3) an iterative Maximum Likelihood (ML) algorithm. Our breast tomosynthesis system acquires 11 low-dose projections over a 50 degree angular range using an a-Si (CsI:Tl) flat-panel detector. The detector was stationary during the acquisition. Quality metrics such as signal difference to noise ratio (SDNR) and artifact spread function (ASF) were used for quantitative evaluation of tomosynthesis reconstructions. The results of the quantitative evaluation were in good agreement with the results of the qualitative assessment. In patient imaging, the superimposed breast tissues observed in two-dimensional (2D) mammograms were separated in tomosynthesis reconstructions by all three algorithms. It was shown in both phantom imaging and patient imaging that the BP algorithm provided the best SDNR for low-contrast masses but the conspicuity of the feature details was limited by interplane artifacts; the FBP algorithm provided the highest edge sharpness for microcalcifications but the quality of masses was poor; the information of both the masses and the microcalcifications were well restored with balanced quality by the ML algorithm, superior to the results from the other two algorithms. PMID:15487747

Low-dose CT imaging has been particularly used in modern medical practice for its advantage on reducing the radiation dose to patients. However, excessive quantum noise is present in low dose X-ray imaging along with the decrease of the radiation dose; thus, there are obvious streak-like artifacts in reconstructed images. The statistical iterative reconstruction approach applied to the noisy sinogram before a filtered back-projection (FBP) is a resolution to deal with the noisy problem. In this paper, the statistical property of the noise sinogram was considered to achieve a satisfactory image reconstruction and a statistical iterative method with energy minimization was proposed to address the problem of streak-like artifacts. Simulations were performed and indicated that the proposed met...

Objectives To determine the influence of iterative reconstruction (IR) on quantitative computed tomography (CT) measurements of emphysema, air trapping, and airway wall and lumen dimensions, compared to filtered back-projection (FBP). Methods Inspiratory and expiratory chest CTs of 75 patients (37 male, 38 female; mean age 64.0???5.7?years) were reconstructed using FBP and IR. CT emphysema, CT air trapping and airway dimensions of a segmental bronchus were quantified using several commonly used quantification methods. The two algorithms were compared using the concordance correlation coefficient (p c) and Wilcoxon signed rank test. Results Only the E/I-ratioMLD as a measure of CT air trapping and airway dimensions showed no significant differences between the algorithms, whereas all CT emp...

Sub-second temporal-resolution tomographic microscopy is becoming a reality at third-generation synchrotron sources. Efficient data handling and post-processing is, however, difficult when the data rates are close to 10-GB-s-1. This bottleneck still hinders exploitation of the full potential inherent in the ultrafast acquisition speed. In this paper the fast reconstruction algorithm gridrec, highly optimized for conventional CPU technology, is presented. It is shown that gridrec is a valuable alternative to standard filtered back-projection routines, despite being based on the Fourier transform method. In fact, the regridding procedure used for resampling the Fourier space from polar to Cartesian coordinates couples excellent performance with negligible accuracy degradation. The stronger d...

The stochastic differential and integral equations describing the system of particles weakly interacting among themselves which are absorbed and scattered by particles of a medium are considered. The time-dependent transport equation with scattering is studied taking into account stochastic nature of parameters in nuclear imaging. Using dynamic attenuated Radon transform the solution of transport equation may be derived taking into account of the scattering as perturbation. We analyze the influence of the random variables upon the image reconstruction both generally and in more details for the case of point source. It is shown by the example of the method of the filtered back projection (FBP) that unaccounted small fluctuations of attenuation coefficient can cause essential distortions of image texture and degradation of the resolution at image reconstruction in single-photon emission computerized tomography (SPECT) and less in X-ray computerized tomography (CT). The mechanism of these distortions is analyzed...

The impulse response of the ultrasonic transducer used for detection is crucial for photoacoustic imaging with high resolution. We demonstrate a reconstruction method that allows the optical absorption distribution of a sample to be reconstructed without knowing the impulse response of the ultrasonic transducer. A convolution relationship between photoacoustic signals measured by an ultrasound transducer and optical absorption distribution is developed. Based on this theory, the projection of the optical absorption distribution of a sample can be obtained directly by deconvolving the recorded PA signal originating from a point source out of that from the sample. And a modified filtered back projection algorithm is used to reconstruct the optical absorption distribution. We constructed a photoacoustic imaging system to validate the reconstruction method and the experimental results demonstrated that the reconstructed images agreed well with the original phantom samples. The spatial resolution of the system reaches 0.3 mm.

We perform angle- and frequency-resolved radar cross section (RCS) measurements on objects at terahertz frequencies. Our RCS measurements are performed on a scale model aircraft of size 5-10 cm in polar and azimuthal configurations, and correspond closely to RCS measurements with conventional radar on full-size objects. The measurements are performed in a terahertz time-domain system with freely propagating terahertz pulses generated by tilted pulse front excitation of lithium niobate crystals and measured with sub-picosecond time resolution. The application of a time domain system provides ranging information and also allows for identification of scattering points such as weaponry attached to the aircraft. The shapes of the models and positions of reflecting parts are retrieved by the filtered back projection algorithm.

Cone beam computed tomography (CBCT) enables volumetric image reconstruction from 2D projection data and plays an important role in image guided radiation therapy (IGRT). Filtered back projection is still the most frequently used algorithm in applications. The algorithm discretizes the scanning process (forward projection) into a system of linear equations, which must then be solved to recover images from measured projection data. The conjugate gradients (CG) algorithm and its variants can be used to solve (possibly regularized) linear systems of equations Ax=b and linear least squares problems minx@?b-Ax@?"2, especially when the matrix A is very large and sparse. Their applications can be found in a general CT context, but in tomography problems (e.g. CBCT reconstruction) they have not wi...

Electrical Capacitance Tomography (ECT) image reconstruction is a key problem that is not well solved due to the influence of soft-field in the ECT system. In this paper, a new hybrid ECT image reconstruction algorithm is proposed by combining Tikhonov regularization theory and Simultaneous Reconstruction Technique (SIRT) algorithm. Tikhonov regularization theory is used to solve ill-posed image reconstruction problem to obtain a stable original reconstructed image in the region of the optimized solution aggregate. Then, SIRT algorithm is used to improve the quality of the final reconstructed image. In order to satisfy the industrial requirement of real-time computation, the proposed algorithm is further been modified to improve the calculation speed. Test results show that the quality of reconstructed image is better than that of the well-known Filter Linear Back Projection (FLBP) algorithm and the time consumption of the new algorithm is less than 0.1 second that satisfies the online requirements.

This work describes a family of attitude estimators that are based on a generalization of Mahony's nonlinear complementary filter. This generalization reveals the close mathematical relationship between the nonlinear complementary filter and the more traditional multiplicative extended Kalman filter. In fact, the bias-free and constant gain multiplicative continuous-time extended Kalman filters may be interpreted as special cases of the generalized attitude estimator. The correspondence provides a rational means of choosing the gains for the nonlinear complementary filter and a proof of the near global asymptotic stability of special cases of the multiplicative extended Kalman filter.

A novel time-domain spectroscopic EPR imaging approach, that is a unique combination of already known techniques, is described. The first one is multi-gradient Single Point Imaging involving pure phase-encoding where the oximetry is based on T2?. Line width derived from T2? is subject to susceptibility effects and therefore needs system-dependent line width calibrations. The second approach utilizes the conventional 90°-?-180° Spin-Echo pulse sequence where the images are obtained by the filtered back-projection after FT of the echoes collected under frequency-encoding gradients. The spatially resolved oximetry information is derived from a set of T2-weighted images. The back-projection images suffer susceptibility artifacts with resolution determined by T2?, but the oximetry based on T2 is quite reliable. The current approach combines Single Point Imaging and the Spin-Echo procedure to take advantage the enhanced spatial resolution associated with the former and the T2 dependent contrast of the latter. Pairs of images are derived choosing two time points located at identical time intervals on either side of the 180° pulse. The refocusing pulse being exactly in the middle of the two points ensures that artifacts associated with susceptibility and field inhomogeneities are eliminated. In addition, the net phase accumulated by the two time points being identical results in identical field of views, thus avoiding the zoom-in effect as a function delay in regular SPI and the associated interpolation requirements employed in T2?-weighted oximetry. The end result is superior image resolution and reliable oximetry. In spite of the fact that projection-reconstruction methods require less number of measurements compared to SPI, the enormous advantage in SNR of the SPI procedure makes the echo-based SPI equally efficient in terms of measurement time. The Fourier reconstruction, line width independent resolution and the true T2-weighting make this novel procedure very attractive for in vivo EPR imaging of tissue oxygen quantitatively.

Glaucoma surgery can be classified as either cyclodestructive (reducing inflow) or filtering (increasing outflow). Filtration has traditionally been the procedure of first resort because of its efficacy and relative predictability, whereas ciliary destruction has been reserved for more refractory ca...

It has been five years since the last in-depth American College of Nuclear Physicians/Society of Nuclear Medicine Symposium on the subject of single photon emission computed tomography (SPECT) was held. Because this subject was nominated as the single most desired topic we have selected SPECT imaging as the basis for this year's program. The objectives of this symposium are to survey the progress of SPECT clinical applications that have taken place over the last five years and to provide practical and timely guidelines to users of SPECT so that this exciting imaging modality can be fully integrated into the evaluation of pathologic processes. The first half was devoted to a consideration of technical factors important in SPECT acquisition and the second half was devoted to those organ systems about which sufficient clinical SPECT imaging data are available. With respect to the technical aspect of the program we have selected the key areas which demand awareness and attention in order to make SPECT operational in clinical practice. These include selection of equipment, details of uniformity correction, utilization of phantoms for equipment acceptance and quality assurance, the major aspect of algorithms, an understanding of filtered back projection and appropriate choice of filters and an awareness of the most commonly generated artifacts and how to recognize them. With respect to the acquisition and interpretation of organ images, the faculty will present information on the major aspects of hepatic, brain, cardiac, skeletal, and immunologic imaging techniques. Individual papers are processed separately for the data base. (TEM)

The acoustic echo problem arises whenever there is acoustic coupling between a loudspeaker and a microphone, such as in a teleconference system. This problem is traditionally solved by using an acoustic echo canceler (AEC), which models the echo path with adaptive filters. Long adaptive filters are ...

Stationary source inverse-geometry CT (SS-IGCT) has been proposed as a new system architecture that has several key advantages over traditional cone beam CT (CBCT). One advantage is the potential for acquiring a large volume of interest with minimal cone-beam artifacts and with very high temporal resolution. We anticipate that SS-IGCT will use large, stationary source arrays, with gaps in between separate source array modules. These gaps make reconstruction challenging because most analytic reconstruction algorithms assume a continuous source trajectory. SS-IGCT is capable of producing the same dataset as a traditional scanner taking multiple overlapping axial scans, but with segments of the views missing from each axial scan because of gaps. We propose the following, two-stage volumetric reconstruction algorithm. In the first stage, the missing rays are estimated in a spatially varying fashion using available data and geometric considerations, and reconstruction proceeds with standard algorithms. The missing data are then re-estimated by a forward projection step. These new estimates are quite good and the reconstruction can be performed again using any algorithm that supports multiple parallel axial scans. Although inspired by iterative reconstruction, our algorithm only needs one "iteration" of forward- and back-projection in practice and is efficient. Simulations of a thorax phantom were performed showing the efficacy of this technique and the ability of SS-IGCT to suppress cone-beam artifacts compared to conventional CBCT. The noise and resolution characteristics are comparable to that of CBCT.

Although non-uniform attenuation correction (NUAC) can supply more accurate absolute quantification, it is not entirely clear whether NUAC provides clear-cut benefits in the routine clinical practice of brain SPET imaging. The aim of this study was to compare the effect of NUAC versus uniform attenuation correction (UAC) on volume of interest (VOI)-based semi-quantification of a large age- and gender-stratified brain perfusion normal database. Eighty-nine healthy volunteers (46 females and 43 males, aged 20-81 years) underwent standardised high-resolution single-photon emission tomography (SPET) with 925 MBq {sup 99m}Tc-ethyl cysteinate dimer (ECD) on a Toshiba GCA-9300A camera with {sup 153}Gd or {sup 99m}Tc transmission CT scanning. Emission images were reconstructed by filtered back-projection and scatter corrected using the triple-energy window correction method. Both non-uniform Chang attenuation correction (one iteration) and uniform Sorenson correction (attenuation coefficient 0.09 cm{sup -1}) were applied. Images were automatically re-oriented to a stereotactic template on which 35 predefined VOIs were defined for semi-quantification (normalisation on total VOI counts). Small but significant differences between relative VOI uptake values for NUAC versus UAC in the infratentorial region were found. VOI standard deviations were significantly smaller for UAC, 4.5% (range 2.6-7.5), than for NUAC, 5.0% (2.3-9.0) (P<0.01). Higher filter roll-off values of the transmission reconstruction filter increased noise in the emission images and altered estimated cortical attenuation coefficients as well as uptake values. In conclusion, semi-quantification based upon reconstruction with UAC results in very similar {sup 99m}Tc-ECD uptake values in healthy volunteers to those obtained with NUAC, although values for the infratentorial region are slightly lower. NUAC produces a slight increase in inter-subject variability. Further study is necessary in various patient populations to establish the full clinical impact of NUAC in brain perfusion SPET. (orig.)

Ways in which failure can occur in reduced-order, orbit determination filter, error covariance calculations are discussed. In the context of this article, reduced-order filters denote nonoptimal filters which include fixed levels of uncertainty in some parameters of the measurement models or in the spacecraft dynamical model which are not explicitly estimated in the filter equations. Failure is defined as an increase in the orbit determination covariance with the addition of data or as an unreasonable growth in the covariance with time, i.e., nonasymptotic behavior of the covariance. Some simple, known cases of failure are discussed along with their traditional remedies. In addition, more modern remedies are discussed which are currently under development at the Jet Propulsion Laboratory. The article first describes the known problems of reduced-order filters when they are employed for orbit determination, and their traditional remedies. Then, having defined these, the relevancy and desirability of the more modern remedies are made apparent.

In this paper, a novel substrate integrated folded waveguide (SIFW) H-plane band-pass filter based on low-temperature co-fired ceramic technology (LTCC) is proposed which employs double H-plane septa of a short-ended evanescent waveguide as an impedance inverter. The filter has advantages of convenient integration, compact, low cost, mass-producibility, and ease of fabrication, and it also has frequency responses similar to those of traditional E-plane double-iris waveguide band-pass filters. To validate the new proposed topology, a three-pole narrowband band-pass filter is designed and fabricated using half-wavelength resonators. A comparison between measured results and simulated results shows good agreement. PMID:22481793

A clinical prototype of the laser optoacoustic imaging system (LOIS) was employed for breast cancer detection and localization in patients with confirmed breast cancer and scheduled for radical mastectomy. The prototype LOIS used a single optical fiber for delivery of laser pulses, an arc shaped 32-element PVDF transducer array for ultrawide-band piezoelectric detection of optoacoustic signals and a single-channel data acquisition card for signal processing. The resonance ultrasound frequency of the 110 micrometers PVDF film was outside detectable range of ultrasound. Spatial resolution of the transducer array was slightly better than 1mm in radial direction and slightly worse than 1 mm in lateral direction. The system was optimized for contrast and sensitivity. Data acquisition, signal conditioning and image processing were significantly improved and optimized resulting in reduced image frame rate of 2 seconds employing 700 MHz Aphlon processor. The computer code for digital signal processing employed band-pass hyper-Gaussian filtering and denoising. An automatic recognition of the optoacoustic signal detected from the irradiated surface was implemented in order to visualize the breast surface and improve the accuracy of tumor localization. Radial back- projection algorithm was employed adopting combination of integration along spherical wavefronts and integration along planar wavefronts (as in Radon transform) for image reconstruction. The system performance was evaluated initially in breast tissue-like phantoms with embedded blood vessels. Clinical studies in breast cancer patients scheduled for surgical mastectomy were performed and compared with x-ray radiography, ultrasound and pathology reports.

OBJECTIVES: To compare native aortic (AV) and mitral valve (MV) image quality on limited-dose retrospectively ECG-gated CTA of the thoracoabdominal aorta reconstructed with iterative reconstruction (IR) and filtered back projection (FBP). METHODS: Fifty patients underwent routine care retrospectively ECG-gated thoracoabdominal limited-dose 256-slice CTA. At 30 % (systole) and 75 % (diastole) of the R-R interval AV and MV were reconstructed using FBP and IR. Objective image quality [density and noise (SD of density measurement)] was measured. Two independent observers scored subjective valve image quality using four-point Likert scales. RESULTS: IR significantly decreased image noise, but did not alter the aorta and interventricular septum density. Interobserver variability was moderate to good. Valve image quality was scored at least moderate in most cases. IR scored one or two Likert scale points higher than FBP in 10 (first observer) and 27 (second observer) scores. Conversely, IR scored one Likert scale point lower than FBP in 1 (first observer) and 4 (second observer) scores. CONCLUSIONS: Limited-dose retrospectively ECG-gated thoracoabdominal CTA enables moderate to excellent evaluation of AV and MV in most patients, in addition to the primary diagnostic question. Image quality is further improved by IR. KEY POINTS : • Thoracoabdominal computed tomographic angiography demonstrates both the aortic and mitral valves. • Iterative reconstruction decreases image noise and increases the SNR/CNR of thoracoabdominal CTA. • Limited-dose retrospectively gated CTA enables moderate-excellent left-sided valvular evaluation. • Iterative CT image reconstruction improves subjective native aortic and mitral valvular evaluation. PMID:23064676

Abstract A very high-resolution small animal positron emission tomograph (PET), which can achieve sub-millimeter spatial resolution, is being developed using silicon pad detectors. The prototype PET for a single slice instrument consists of two 1 mm thick silicon pad detectors, each containing a 32×16 array of 1.4×1.4 mm pads readout with four VATAGP3 chips which have 128 channels low-noise self-triggering ASIC in each chip, coincidence units, a source turntable and tungsten slice collimator. The silicon detectors were located edgewise on opposite sides of a 4 cm field-of-view to maximize efficiency. Energy resolution is dominated by electronic noise, which is 0.98% (1.38 keV) FWHM at 140.5 keV. Coincidence timing resolution is 82.1 ns FWHM and coincidence efficiency was measured to be 1.04×10?3% from two silicon detectors with annihilation photons of 18F source. Image data were acquired and reconstructed using conventional 2-D filtered-back projection (FBP) and a maximum likelihood expectation maximizat...

Variation in computed tomography (CT) image grayscale and spatial geometry due to specimen orientation, magnification, voxel size, differences in X-ray photon energy and limited field-of-view during the scan, were evaluated in repeated micro-CT scans of iliac crest biopsies and test phantoms. Using the micro-CT scanner on beamline X2B at the Brookhaven National Laboratory's National Synchrotron Light Source, 3-D micro-CT images were generated. They consisted of up to 1024 X 24002, 4-mum cubic voxels, each with 16-bit gray-scale. We also reconstructed the images at 16-, 32-, and 48-mum voxel resolution. Scan data were reconstructed from the complete profiles using filtered back-projection and from truncated profiles using profile-extension and with a Local reconstruction algorithm. Three biopsies and one bonelike test phantom were each rescanned at three different times at annual intervals. For the full-data-set reconstructions, the reproducibility of the estimates of mineral content of bone at mean bone opacity value, was {+-}28.8 mg/cm3, i.e., 2.56%, in a 4-mum cubic voxel at the 95% confidence level. The reproducibility decreased with increased voxel size. The interscan difference in imaged bone volume ranged from 0.86 {+-} 0.64% at 4-mum voxel resolution, and 2.64 {+-} 2.48% at 48 mum.

Scan time of spectral-CTs is much longer than conventional CTs due to limited number of x-ray photons detectable by photon-counting detectors. However, the spectral pixel information in spectral-CT has much richer information on physiological and pathological status of the tissues than the CT-number in conventional CT, which makes the spectral- CT one of the promising future imaging modalities. One simple way to reduce the scan time in spectral-CT imaging is to reduce the number of views in the acquisition of projection data. But, this may result in poorer SNR and strong streak artifacts which can severely compromise the image quality. In this work, spectral-CT projection data were obtained from a lab-built spectral-CT consisting of a single CdTe photon counting detector, a micro-focus x-ray tube and scan mechanics. For the image reconstruction, we used two iterative image reconstruction methods, the simultaneous iterative reconstruction technique (SIRT) and the total variation minimization based on conjugate gradient method (CG-TV), along with the filtered back-projection (FBP) to compare the image quality. From the imaging of the iodine containing phantoms, we have observed that SIRT and CG-TV are superior to the FBP method in terms of SNR and streak artifacts.

Single photon emission computed tomography (SPECT) reconstructions are performed using maximum a posteriori (penalized likelihood) estimation via the expectation maximization algorithm. Due to the large number of computations, the algorithms are performed on a massively parallel single-instruction multiple-data computer. Computation times for 200 iterations using Good's roughness rotationally invariant roughness penalty are on the order of 5 min for a 64 [times] 64 image with 96 view angles on an AMT-DAP 4096 processor machine, and 1 min on a MasPar 4096 processor machine. Computer simulations have been performed using parameters for the Siemens gamma camera and clinical brain scan parameters comparing two regularization techniques to conventional reconstructions. Regularization by kernel sieves and penalized likelihood with Good's rotationally invariant roughness measure are compared to filtered back-projection. Twenty-five independent sets of data are reconstructed for the pie and Hoffman brain phantoms. The average variance and average deviation are examined in various areas of the brain phantom. It is shown that while the geometry of the area examined greatly affects the observed results, in all cases the reconstructions using Good's roughness give superior variance and bias results to the two alternative methods.

A novel image prior with mixed continuity constraints is proposed for the Bayesian positron emission tomography image reconstruction of human brains. Assume that a human brain can be partitioned into four tissue classes: gray matter, white matter, cerebral spinal fluid, and partial volume. And each partial volume image voxel consists of an arbitrary mixture among pure tissues. The brain image is then modeled as a piece-wise smooth function through a Gibbs prior with the image intensity of each region governed by the thin- plate energy function. We apply first and second order edge detection techniques to estimate region boundaries, and then categorize these boundaries based on the resulting edge maps. Rather than use the binary processes representing region boundaries such as weak-membrane or weak-plate (WP) models, we adopt a controlled-continuity approach to influence boundary formation. We refer to this model as a modified (WP) model with controlled continuity. We present the results of a computer simulated phantom study in which partial volume effects are explicitly modeled. Results indicate that we obtain superior region of interest quantitation using this approach in comparison to a partial volume correction method that has previously been proposed for quantitation using filtered back-projection image.

This was a CRADA to transfer the x-ray tomographic microscope technology to the Quality Technology Center of General Electric Air Craft Engines Division in Ohio. The x-ray tomographic microscope (XTM) is a high resolution, three-dimensional imaging system that can be used to image materials microstructures noninvasively. The apparatus consists of an x-ray source, x-ray collimators, sample positioning stages, a fluorescent screen to convert x-rays to visible light, an optical lens, and a thermoelectrically cooled charge coupled device detector. The details of the microscope`s design have been described elsewhere. In practice, the sample to be imaged is positioned on a rotating stage. The sample is initially translated out of the x-ray path, and an image is obtained of the incident x-ray beam (the reference image). Next, the sample is placed between the x-ray path and the scintillator, and another image, the projection image, is acquired. The ratios of the logarithms of the reference image and the projection image provide values of the integrated x-ray attenuation through the sample. By rotating the sample in discrete angular increments through 180 degrees, enough data can be obtained to reconstruct the two-dimensional projection images into a three-dimensional image of the mineral density distribution in the sample. This reconstruction procedure, known as reconstruction from projections, is usually performed with the technique of Fourier-filtered back-projection. Using the present microscope, a 1 cubic centimeter volume can be imaged with five micrometer volume elements in about one hour or less.

Superposing the images of ECT on x-ray CT and development of a new ..gamma..-camera for this purpose were studied. As for ECT, LEOV ..gamma..-camera (Searle) was used, and the reconstruction of the images was carried out by filtered back projection method. CT/T8800 (GE) was applied for x-ray CT. The outlines of organs by x-ray CT were superposed on the magnified images of ECT taken at the same plane. Out of 20 cases inspected, hyperthyroidism and primary lung cancer with metastasis of lymph nodes, which were diagnosed by this method were introduced. For ECT, sup(99m)Tc-pertechnetate was used for the former cases; in the latter case, sup(99m)Tc-MAA and /sup 67/Ga-citrate were used. In order to reduce the difficulties due to the different position of the patient in ECT and x-ray CT, a new ..gamma..-camera (GCA 401-5, Toshiba Co.) with a rolling gantry around the spine-positioned patient was developed. The new device enables to adjust the slices of ECT to those of x-ray CT.

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...

The plasma density distribution of plasmasphere in the geomagnetic equatorial plane can help us study the magnetosphere like plasmasphere, ionosphere and their kinetics. In this paper, we introduce a new inversion method, GE-ART, to calculate the plasma density distribution in the geomagnetic equatorial plane from the Extreme Ultraviolet (EUV) data of IMAGE satellite under the assumption that the plasma density is constant along each geomagnetic field line. The new GE-ART algorithm was derived from the traditional Algebraic Reconstruction Techniques (ART) in Computed Tomography (CT) which was different from the several existing methods. In this new method, each value of the EUV image data was back-projected evenly to the geomagnetic field lines intersected by this EUV sight. A 3-D inversion matrix was produced by the contributions of all the voxels contained in the plasmasphere covered by the EUV sensor. That is, we considered that each value of the EUV image data was relative to the plasma densities of all the voxels passed through by the corresponding EUV radiation, which is the biggest difference to all the existing inversion methods. Finally, the GE-ART algorithm was evaluated by the real EUV data from the IMAGE satellite.

Multislice CT evaluation of prosthetic heart valves (PHV) is limited by PHV-related artifacts. We assessed the influence of different kV settings, a metal artifact reduction filter (MARF) and an iterative reconstruction algorithm (IR) on PHV-induced artifacts in an in vitro model. A Medtronic-Hall tilting disc and St Jude bileafet PHV were imaged using a 64-slice scanner with 100 kV/165 mAs, 120 kV/100 mAs, 140 kV/67 mAs at an equal CTDI(vol). Images were reconstructed with (1) filtered back projection (FBP), (2) IR, (3) MARF and (4) MARF and IR. Hypo- and hyperdense artifacts volumes (mean mm(3) ± SD) were quantified with 2 thresholds (?-50 and ?175 Hounsfield Units). Image noise was measured and the presence of secondary artifacts was scored by 2 observers independently. Mean hypodense artifacts for the Medtronic-Hall/St Jude valve (FBP) were 966 ± 23/1,738 ± 21 at 100 kV, 610 ± 13/991 ± 12 at 120 kV, and 420 ± 9/634 ± 9 at 140 kV. Compared to FBP, hypodense artifact reductions for IR were 9/8 %, 10/7 % and 12/6 % respectively, for MARF 92 %/84 %, 89/81 % and 86/77 % respectively; for MARF + IR 94/85 %, 92/82 %, and 90/79 % respectively. Mean hyperdense artifacts for the Medtronic-Hall/St Jude valve were 5,530 ± 48/6,940 ± 70 at 100 kV, 5,120 ± 42/6,250 ± 53 at 120 kV, and 5,011 ± 52/6,000 ± 0 at 140 kV. Reductions for IR were 2/2 %, 2/3 % and 3/4 % respectively, for MARF were 9/30 %, 0/25 %, 5/22 % respectively, MARF + IR 12/32 %, 4/27 % and 7/25 % respectively. Secondary artifacts were found in all MARF images. Image noise was reduced in the IR images. In vitro PHV-related artifacts can be reduced by increasing kV despite maintaining identical CTDI(vol). Although MARF is more effective than IR, it induces secondary artifacts. PMID:22476910

In order to improve the imaging contrast and resolution in photoacoustic tomography(PAT), the deconvolution between the transducer impulse response and the recorded photoacoustic(PA) signal of the tissue phantom is often used. The suppression of noise is critical in the deconvolution. Compared with the traditional band-pass filter in Fourier domain, wiener filter is more appropriate for the wide band PA signal. The scaling parameter in wiener filter is hard to determine using the traditional Fourier domain method. To solve the problem, the deconvolution algorithm with wiener filter based on the wavelet transform is presented. The scaling parameter is estimated using discrete wavelet transform(DWT) by its multi-resolution analysis(MRA) ability. The white noise had been effectively suppressed. Both numerical simulation and experimental results demonstrated that the contrast and resolution of PA images had been improved.

A computed tomography device comprising a subtraction unit which obtains differential data strings representing the difference between each time-serial projection data string of a group of projection data strings corresponding to a prospective reconstruction image generated by projection data strings acquired by a data acquisition system, a convolution unit which convolves each time-serial projection data string of the group of projection data strings corresponding to the prospective reconstruction image, and a back-projection unit which back-projects the convolved data strings.

A combination deconvolution method is presented to increase the time resolution of an ultrasonic echo signal by reconstructing outside pass-band data. By the modified traditional Wiener inverse filter the filtered data are estimated, an autoregression (AR) model is obtained for these data inside the pass bands. Only the high frequency side data out of the pass bands are renewed by the autoregressive spectral extrapolation method. The optimized estimation is reconstructed using the combination of renewed and filtered data inside the pass bands. The results from the computer simulation and the experiments on measuring the thickness of thin multilayer materials show that this approach has improved time resolution performance.

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.

Awide variety of challenges now exist to beverage manufacturers which require the rapid detection of spoilage microorganisms. An alternative to the traditional plate count method has been sought. EMD Millipore has developed a fluorescent staining system for the quantitative detection of viable and culturable contaminants in filterable samples.

An audio signal can be represented by a Time-Varying Auto- Regressive (TVAR) model, whose parameters can be estimated by a particle filter. Since the original parameters are unavailable for real signals, an evaluation of the estimation may be traditionally performed through indirect criteria such as...

The fundamental problems in the traditional frequency do- main approaches to convolutive blind source separation are 1) arbitrary permutations and 2) arbitrary scaling in each frequency bin of the esti- mated filters or sources. These ambiguities are corrected by taking into account some specific pr...

combine ionospheric measurements with the physics model: a sparse, traditional. Kalman filter to estimate .... code version is operationally used at JPL to compete with. GIM solutions with ..... simulation despite the use of O+ exclusively. This will ..... Ping, J., K. Matsumoto, K. Heki, A. Saito, P. Callahan, L. Potts, and. C. Shum ...

The traditional recommender systems are usually oriented to general situations in daily lives (e.g. recommend movies, books, music, news and etc.), but seldom cover the recommendation scenarios for the collaborative team environments. We have done an explorative study on collaborative filtering mech...

The use of the adaptive statistical iterative reconstruction (ASIR) algorithm has been shown to reduce radiation doses in adults undergoing abdominal CT studies while preserving image quality. To our knowledge, no studies have been done to validate the use of ASIR in children. To retrospectively evaluate differences in radiation dose and image quality in pediatric CT abdominal studies utilizing 40% ASIR compared with filtered-back projection (FBP). Eleven patients (mean age 8.5 years, range 2-17 years) had separate 40% ASIR and FBP enhanced abdominal CT studies on different days between July 2009 and October 2010. The ASIR studies utilized a 38% mA reduction in addition to our pediatric protocol mAs. Study volume CT dose indexes (CTDI{sub vol}) and dose-length products (DLP) were recorded. A consistent representative image was obtained from each study. The images were independently evaluated by two radiologists in a blinded manner for diagnostic utility, image sharpness and image noise. The average CTDI{sub vol} and DLP for the 40% ASIR studies were 4.25 mGy and 185.04 mGy-cm, compared with 6.75 mGy and 275.79 mGy-cm for the FBP studies, representing 37% and 33% reductions in both, respectively. The radiologists' assessments of subjective image quality did not demonstrate any significant differences between the ASIR and FBP images. In our experience, the use of 40% ASIR with a 38% decrease in mA lowers the radiation dose for children undergoing enhanced abdominal examinations by an average of 33%, while maintaining diagnostically acceptable images. (orig.)

RATIONALE AND OBJECTIVES: Computed tomographic angiography is the standard in routine follow-up after endovascular aneurysm repair, causing radiation exposure; thus, dose-saving strategies should be applied. The aim of this study was to evaluate the novel sinogram-affirmed iterative reconstruction (SAFIRE) algorithm in terms of clinical usability and potential reduction of radiation exposure. MATERIALS AND METHODS: Forty-six patients underwent computed tomographic angiographic follow-up after endovascular aneurysm repair. Data were acquired using a dual-source computed tomographic scanner running both x-ray tubes at the same voltage (120 kV). Raw data were reconstructed using projections of both tubes with filtered back projection (FBP) and of only one tube with FBP and SAFIRE, corresponding to synthetic acquisition with half the radiation dose of the clinical routine radiation dose. Image sets were objectively compared regarding signal-to-noise ratio and edge sharpness. Two radiologists independently assessed a set of subjective criteria, including diagnostic usability, depiction of contrasted vessels, and image noise. RESULTS: Half-dose (HD) SAFIRE images showed significantly higher signal-to-noise ratios compared to full-dose FBP images (P subjectively assessed parameters, such as diagnostic usability and depiction of contrasted vessels, were rated similar for HD SAFIRE and full-dose FBP images. Full-dose FBP images depicted fine anatomic structures more clearly (P < .05), while HD SAFIRE data sets showed less noise (P < .01). HD FBP images performed worse on all criteria (P < .001). Interrater agreement was good (? = 0.74-0.80). CONCLUSIONS: Using the SAFIRE algorithm, the radiation dose of high-contrast abdominal computed tomographic angiography is reducible from routine clinical levels by up to 50% while maintaining good image quality and diagnostic accuracy. PMID:23099242

This study aimed to investigate a method for empirically evaluating 3D imaging task performance of breast tomosynthesis imaging systems. A simulation and experimental approach was used to develop a robust method for performance assessment. To identify a method for experimentally assessing the 3D modulation transfer function (MTF), a breast tomosysnthesis system was first simulated using cascaded system analysis to model the signal and noise characteristics of the projections. A range of spheres with varying contrast and size were reconstructed using filtered back projection from which the 3D MTF was evaluated. Results revealed that smaller spheres result in lower artifacts in the measured MTF, where a sphere of 0.5 mm was found ideal for experimental purposes. A clinical tomosynthesis unit was used as a platform for quantifying the effect of acquisition and processing parameters (e.g., angular extent and sampling, dose, and voxel size) on breast imaging performance. The 3D noise-power spectrum (NPS) was measured using a uniform phantom and 3D MTF was measured using 0.5 mm ruby spheres. These metrics were combined with a mathematical description of imaging task to generate a figure of merit called the detectability index for system evaluation and optimization. Clinically relevant imaging tasks were considered, such as the detection and localization of a spherical mass. The detectability index was found to provide a useful metric that accounts for the complex 3D imaging characteristics of breast tomosynthesis. Results highlighted the dependence of optimal technique on the imaging task. They further provided initial validation of an empirically assessed figure of merit for clinical performance assessment and optimization of breast tomosynthesis systems.

Background:?Computed tomography venography (CTV) is clinically useful and widely available for the detection of deep vein thrombosis. Disadvantages of CTV are the need for a larger amount of i.v. contrast material (CM) and radiation exposure. A low-tube-voltage technique with iterative reconstruction may overcome this problem. The aim of this study was to investigate the effects of hybrid iterative reconstruction (HIR) on image quality at low-tube-voltage CTV. Methods and Results:?Forty patients (26 women, 14 men; mean age, 59.2±18.3 years) underwent CTV under an 80- or 120-kV protocol (CT dose index volume=10.3mGy vs. 14.9mGy, CM dose=540mgI/kg vs. 690mgI/kg) on a 64-detector CT. Quantitative parameters (ie, venous attenuation, image noise, and contrast-to-noise ratio [CNR]) were calculated and the image quality was scored on a 4-point scale. In step 1, the 80- and 120-kV protocols were compared under filtered back projection (FBP). In step 2, the 80-kV protocol with HIR was compared with the 120-kV protocol with FBP. In step 1, the visual scores were significantly higher under the 120-kV protocol; there was no significant difference in CNR between the protocols. In step 2, CNR was significantly higher under the 80-kV protocol with HIR than the 120-kV protocol with FBP. The visual scores of the 2 protocols were comparable. Conclusions:?The 80-kV CTV with HIR allows for a reduction in the radiation dose by 30% and the CM dose by 20% without image quality degradation.??(Circ J?2012; 76: 2614–2622)   

Several resolution recovery (RR) methods have been developed. This study was aimed to validate the following performance of the advanced RR methods: Evolution™, Astonish™, Flash3D™, and 3D-OSEM. We compared the advanced RR method with filtered back projection (FBP) and standard order-subset expectation maximization (OSEM) using resolution (RES), cylinder/sphere (CYS), and myocardial (MYD) digital phantoms. The RES phantom was placed in three spheres. Sixteen spheres (hot and cold) were then placed in a concentric configuration (diameter: 96-9.6 mm) inside the CYS phantom. The MYD phantom was created by computer simulation with the use of an electron ?-shower 4 (EGS4) and it included two left ventricular defects in the myocardium. The performance was evaluated at source-to-detector distances (R-distance) of 166, 200, and 250 mm with reconstruction parameters (product of subset and iteration: SI) with use of the resolution recovery factor, count recovery, normalized mean square error (NMSE), and %CV. According to increased SI updates, the value of the FWHM decreased, and the effect was more obvious as the R-distance increased. The spatial resolution of the advanced RR method was 20 % better than that of FBP and OSEM. The resolution recovery ratio was 80 %, and the count recovery was maintained only in objects with a diameter of >30 mm in the advanced RR method. The NMSE and %CV was 50 and 30 % improved over FBP and OSEM, respectively. The advanced RR method caused overestimation due to Gibbs's phenomenon in the marginal region when the diameter of the sphere was 16-28.8 mm. PMID:22791082

Adaptive Statistical Iterative Reconstruction (ASIR) is a new imaging reconstruction technique recently introduced by General Electric (GE). This technique, when combined with a conventional filtered back-projection (FBP) approach, is able to improve the image noise reduction. To quantify the benefits provided on the image quality and the dose reduction by the ASIR method with respect to the pure FBP one, the standard deviation (SD), the modulation transfer function (MTF), the noise power spectrum (NPS), the image uniformity and the noise homogeneity were examined. Measurements were performed on a control quality phantom when varying the CT dose index (CTDIvol) and the reconstruction kernels. A 64-MDCT was employed and raw data were reconstructed with different percentages of ASIR on a CT console dedicated for ASIR reconstruction. Three radiologists also assessed a cardiac pediatric exam reconstructed with different ASIR percentages using the visual grading analysis (VGA) method. For the standard, soft and bone reconstruction kernels, the SD is reduced when the ASIR percentage increases up to 100% with a higher benefit for low CTDIvol. MTF medium frequencies were slightly enhanced and modifications of the NPS shape curve were observed. However for the pediatric cardiac CT exam, VGA scores indicate an upper limit of the ASIR benefit. 40% of ASIR was observed as the best trade-off between noise reduction and clinical realism of organ images. Using phantom results, 40% of ASIR corresponded to an estimated dose reduction of 30% under pediatric cardiac protocol conditions. In spite of this discrepancy between phantom and clinical results, the ASIR method is as an important option when considering the reduction of radiation dose, especially for pediatric patients.

The main topics of this thesis are ultrasonic tomography and ultrasonic determination of elastic stiffness constants. Both issues are based on a synthetic array with transducer elements distributed uniformly along a circular aperture, i.e., a circular aperture array. The issues are treated both theoretically and experimentally by broadband pulse techniques. Ultrasonic tomography, UCT, from a circular aperture is a relatively new imaging technique in Non-destructive Evaluation (NDE) to acquire cross sectional images in bulk materials. A filtered back-projection algorithm is used to reconstruct images in four different experiments and results of attenuation, velocity and reflection tomograms in Plexiglas of AlSi-alloy cylinders are presented. Two kinds of ultrasonic tomography are introduced: bistatic and monostatic imaging. Both techniques are verified experimentally by Plexiglas cylinders. Different reconstruction artifacts are discussed and theoretical resolution constraints are discussed for various configurations of the circular aperture array. The monostatic technique is used in volumetric imaging. In the experimental verification artificial and real discontinuities in a cylindrical AlSi-alloy are compared with similar discontinuities in a Plexiglas specimen. Finally, some limitations to UCT are discussed. The circular aperture array is used to determine five independent elastic stiffness constants of a unidirectional glass/PET (Poly Ethylene Teraphtalate) laminate. Energy flux propagation and attenuation of ultrasonic waves are considered and velocity surfaces are calculated for different planes of interest. Relations between elastic stiffness constants and engineering constants (i.e., Young`s moduli, shear moduli and Poisson`s ratios) are discussed for an orthotropic composite. Six micromechanical theories are reviewed, and expressions predicting the elastic engineering constants are evaluated. The micromechanical predicted elastic stiffness constants for the unidirectional glass/PET laminate are compared with ultrasonic and mechanical test results. Finally, the capabilities and limitations of the applied ultrasonic method are discussed. (au) 15 tabs., 103 ills., 203 refs.

This study involved challenging nuclear grade high-efficiency particulate air (HEPA) filters under a variety of conditions that can arise in Department of Energy (DOE) applications such as: low or high RH, controlled and uncontrolled challenge, and filters with physically damaged media or seals (i.e., leaks). Reported findings correlate filter function as measured by traditional differential pressure techniques in comparison with simultaneous instrumental determination of up and down stream PM concentrations. Additionally, emission rates and failure signatures will be discussed for filters that have either failed or exceeded their usable lifetime. Significant findings from this effort include the use of thermocouples up and down stream of the filter housing to detect the presence of moisture. Also demonstrated in the moisture challenge series of tests is the effect of repeated wetting of the filter. This produces a phenomenon referred to as transient failure before the tensile strength of the media weakens to the point of physical failure. An evaluation of the effect of particle size distribution of the challenge aerosol on loading capacity of filters is also included. Results for soot and two size distributions of KCl are reported. Loading capacities for filters ranged from approximately 70 g of soot to nearly 900 g for the larger particle size distribution of KCl. (authors)

Digital filter design can be performed very efficiently using modern computer tools. The drawback of the numeric-based tools is that they usually generate a tremendous amount of numeric data, and the user might easily lose insight into the phenomenon being investigated. The computer algebra systems successfully overcome some problems encountered in the traditional numeric-only approach. In this paper, we introduce an original approach to algorithm development and digital filter design using a computer algebra system. The main result of the paper is the development of an algorithm for an infinite impulse response (IIR) filter design that, theoretically, is impossible to be implemented using the traditional approach. We present a step-by-step procedure which includes derivations of closed-fo...

Finite impulse response filters (FIR filters) are very commonly used in digital signal processing (DSP) applications and are traditionally implemented using ASICs or DSP-processors. For FPGA implementation, due to the high throughput rate and large computational power required under real-time constraints, they are a challenging subject. Indeed, the limitation of resources on FPGA, i.e., logic blocks and flip flops, and furthermore, the high routing delays, requires compact implementations of the circuits. Three approaches for implementation of high-performance symmetric FIR filters on lookup table-based FPGAs will be considered in this paper. Fully parallel distributed arithmetic, table lookup multiplication, and conventional hardware multiplication. Implementation results will be illustrated by an 8 taps 8 bits symmetric FIR filter, and comparative considerations of the above approaches invoked for Xilinx FPGAs will be also shown.

Extended Kalman filtering is an intelligent and optimal means for estimating the state of a dynamic system. In order to use extended Kalman filtering to estimate the state of charge (SOC), we require a mathematical model that can accurately capture the dynamics of battery pack. In this paper, we propose a stochastic fuzzy neural network (SFNN) instead of the traditional neural network that has filtering effect on noisy input to model the battery nonlinear dynamic. Then, the paper studies the extended Kalman filtering SOC estimation method based on a SFNN model. The modeling test is realized on an 80Ah Ni/MH battery pack and the Federal Urban Driving Schedule (FUDS) cycle is used to verify the SOC estimation method. The maximum SOC estimation error is 0.6% compared with the real SOC obtaine...

Camera calibration plays an important role in the field of machine vision applications. During the process of camera calibration, nonlinear optimization technique is crucial to obtain the best performance of camera parameters. Currently, the existing optimization method aims at minimizing the distance error between the detected image point and the calculated back-projected image point, based on 2D image pixels coordinate. However, the vision measurement process is conducted in 3D space while the optimization method generally adopted is carried out in 2D image plane. Moreover, the error criterion with respect to optimization and measurement is different. In other words, the equal pixel distance error in 2D image plane leads to diverse 3D metric distance error at different position before the camera. All the reasons mentioned above will cause accuracy decrease for 3D vision measurement. To solve the problem, a novel optimization method of camera parameters used for vision measurement is proposed. The presented method is devoted to minimizing the metric distance error between the calculated point and the real point in 3D measurement coordinate system. Comparatively, the initial camera parameters acquired through linear calibration are optimized through two different methods: one is the conventional method and the other is the novel method presented by this paper. Also, the calibration accuracy and measurement accuracy of the parameters obtained by the two methods are thoroughly analyzed and the choice of a suitable accuracy evaluation method is discussed. Simulative and real experiments to estimate the performance of the proposed method on test data are reported, and the results show that the proposed 3D optimization method is quite efficient to improve measurement accuracy compared with traditional method. It can meet the practical requirement of high precision in 3D vision metrology engineering.

This paper proposes a new technique based on nonlinear Adaptive Median filter (AMF) for image restoration. Image denoising is a common procedure in digital image processing aiming at the removal of noise, which may corrupt an image during its acquisition or transmission, while retaining its quality. This procedure is traditionally performed in the spatial or frequency domain by filtering. The aim of image enhancement is to reconstruct the true image from the corrupted image. The process of image acquisition frequently leads to degradation and the quality of the digitized image becomes inferior to the original image. Filtering is a technique for enhancing the image. Linear filter is the filtering in which the value of an output pixel is a linear combination of neighborhood values, which can produce blur in the image. Thus a variety of smoothing techniques have been developed that are non linear. Median filter is the one of the most popular non-linear filter. When considering a small neighborhood it is highly e...

An ordered subsets (OS) reconstruction algorithm based on the median root prior (MRP) and inter-update median filtering was implemented for the reconstruction of low count statistics transmission (TR) scans. The OS-MRP-TR algorithm was evaluated using an experimental phantom, simulating positron emission tomography (PET) whole-body (WB) studies, as well as patient data. Various experimental conditions, in terms of TR scan time (from 1 h to 1 min), covering a wide range of TR count statistics were evaluated. The performance of the algorithm was assessed by comparing the mean value of the attenuation coefficient (MVAC) of known tissue types and the coefficient of variation (CV) for low-count TR images, reconstructed with the OS-MRP-TR algorithm, with reference values obtained from high-count TR images reconstructed with a filtered back-projection (FBP) algorithm. The reconstructed OS-MRP-TR images were then used for attenuation correction of the corresponding emission (EM) data. EM images reconstructed with attenuation correction generated by OS-MRP-TR images, of low count statistics, were compared with the EM images corrected for attenuation using reference (high statistics) TR data. In all the experimental situations considered, the OS-MRP-TR algorithm showed: (1) a tendency towards a stable solution in terms of MVAC; (2) a difference in the MVAC of within 5% for a TR scan of 1 min reconstructed with the OS-MRP-TR and a TR scan of 1 h reconstructed with the FBP algorithm; (3) effectiveness in noise reduction, particularly for low count statistics data [using a specific parameter configuration the TR images reconstructed with OS-MRP-TR(1 min) had a lower CV than the corresponding TR images of a 1-h scan reconstructed with the FBP algorithm]; (4) a difference of within 3% between the mean counts in the EM images attenuation corrected using the OS-MRP-TR images of 1 min and the mean counts in the EM images attenuation corrected using the OS-MRP-TR images of 1 h; (5) preservation of ''good'' image quality for both TR and EM reconstructed images. In conclusion, the OS-MRP-TR algorithm is particularly suitable for WB PET studies, allowing: (1) the acquisition of a very short TR scan (within 1 min), (2) the reconstruction of such TR data in low-noise TR images and (3) the use of the reconstructed OS-MRP-TR images for attenuation correction of corresponding EM data. (orig.)

In this paper, a generic computational primitive is developed for the implementation of any arbitrary order one-dimensional or two-dimensional FIR or IIR digital filter. This computational primitive can form the basis for a single chip processor for one-dimensional and two-dimensional digital signal processing. A multiprocessor architecture for real-time implementation of spatial domain filters is developed with each processing unit in the network implementing the computational primitive. This multiprocessor system has a simple control scheme, a simple interconnection network, a very high efficiency, and low data transfers and storage requirements. Thus, it avoids the bottlenecks associated with traditional parallel computers and multiprocessor systems.

A chromatic modulator has been proposed to enable the separate detection of the red, green, and blue (RGB) color components of the same scene by a single charge-coupled device (CCD), active-pixel sensor (APS), or similar electronic image detector. Traditionally, the RGB color-separation problem in an electronic camera has been solved by use of either (1) fixed color filters over three separate image detectors; (2) a filter wheel that repeatedly imposes a red, then a green, then a blue filter over a single image detector; or (3) different fixed color filters over adjacent pixels. The use of separate image detectors necessitates precise registration of the detectors and the use of complicated optics; filter wheels are expensive and add considerably to the bulk of the camera; and fixed pixelated color filters reduce spatial resolution and introduce color-aliasing effects. The proposed chromatic modulator would not exhibit any of these shortcomings. The proposed chromatic modulator would be an electromechanical device fabricated by micromachining. It would include a filter having a spatially periodic pattern of RGB strips at a pitch equal to that of the pixels of the image detector. The filter would be placed in front of the image detector, supported at its periphery by a spring suspension and electrostatic comb drive. The spring suspension would bias the filter toward a middle position in which each filter strip would be registered with a row of pixels of the image detector. Hard stops would limit the excursion of the spring suspension to precisely one pixel row above and one pixel row below the middle position. In operation, the electrostatic comb drive would be actuated to repeatedly snap the filter to the upper extreme, middle, and lower extreme positions. This action would repeatedly place a succession of the differently colored filter strips in front of each pixel of the image detector. To simplify the processing, it would be desirable to encode information on the color of the filter strip over each row (or at least over some representative rows) of pixels at a given instant of time in synchronism with the pixel output at that instant.

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

International crude oil prices are an important part of the economy, and trends in changing oil prices have an effect on financial markets. Traditional hybrid analysis methods for international crude oil prices, such as wavelet transform and back propagation neural network (BPNN), seek synergy effects by sequentially filtering data through different models. However, these estimation methods cause loss of information through the introduction of biases in each filtering step, which are aggregated throughout the process when model assumptions are violated, and the traditional BPNN model does not have forecasting ability. In this study, we constructed a multiple wavelet recurrent neural network (MWRNN) simulation model, in which trend and random components of crude oil and gold prices were con...

The grid connected Wind Energy Conversion Systems (WECSs) have two practical topologies, the traditional fixed speed and the new variable speed. Variable speed systems have several advantages over the traditional ones, such as reduction of mechanical stress and increase in captured energy; however, the systems need a Power Electronic (PE) converter, in which the machine is connected to the grid via the PE converter. To improve the power quality and decrease electrical losses in the variable speed WECS, choosing a full control PE converter or a simple PE converter including an active filter is essential. In this paper, a new modulation technique is proposed to be used in a Shunt Active Filter (SAF) to improve the output current harmonics of a WECS, including a Permanent Magnet Synchronous G...

Traditional one-bit ?? modulators used for A/D and D/A conversion produce very predominant tones near half the sample rate which might intermodulate in the analog converter section and cause in-band tones. This paper demonstrates how the use of chaos can substitute dither as a means for extinguishing these tones. Especially, modulator feedback filters derived from noise transfer functions having an all-pass term seem very promising

Sintered metal and ceramic membrane filtration media have a broad range of applicability due to their mechanical strength, chemical resistance, and their ability to withstand conditions of excessive heat and moisture. Additionally, these media can be cleaned with back pulses of liquid or air. However, these filters are sufficiently more expensive than traditional media, and must last significantly longer in order to be cost effective. Thus, it is necessary to confirm that these filter media maintain efficiency after repeated cleaning. A series of tests has been conducted using ceramic membrane, sintered metal fiber, and powdered sintered metal filter media supplied from three manufacturers to evaluate their performance after repeated loading and washing cycles. The media were loaded to app...

The increasing use of power electronics in aircraft power systems to enable new, more-electric aircraft (MEA) functions has also led to increasing EMI emission. EMI filters may account for more than 50% of the overall volume and weight of high-power converters such as variable-speed motor drives. The traditional approach to mitigating EMI requires functional prototypes and EMI measurements before filter design can start. Such an empirical, EMI-last approach results in designs that are suboptimal at best and is a major cause for schedule delay and disruption. This paper reviews recent research on EMI modeling and system solutions to EMI, empha- sizing conducted emission of three-phase converters and variable-speed drives that dominate system EMI filtering requirements. The goal is to enable a concurrent-EMI design approach and to develop optimal system solutions that minimize the overall volume and size.

This paper proposes a novel algorithm for speckle reduction in medical ultrasound imaging while preserving the edges with the added advantages of adaptive noise filtering and speed. We propose a nonlinear image diffusion algorithm that incorporates two local parameters of image quality, namely, scatterer density and texture-based contrast in addition to gradient, to weight the nonlinear diffusion process. The scatterer density is proposed to replace the existing traditional measures of quality of the ultrasound diffusion process such as MSE, RMSE, SNR, and PSNR. This novel diffusion filter was then implemented using back propagation neural network for fast parallel processing of volumetric images. The experimental results show that weighting the image diffusion with these parameters produces better noise reduction and produces a better edge detection quality with reasonable computational cost. The proposed filter can be used as a preprocessing phase before applying any ultrasound segmentation or active contour model processes. PMID:17945739

Traditionally, Optimal Filtering Algorithm has been implemented using general purpose programmable DSP chips. Alternatively, new FPGAs provide a highly adaptable and flexible system to develop this algorithm. TileCal ROD is a multi-channel system, where similar data arrives at very high sampling rates and is subject to simultaneous tasks. It include different FPGAs with high I/O and with parallel structures that provide a benefit at a data analysis. The Optical Multiplexer Board is one of the elements presents in TileCal ROD System. It has FPGAs devices that present an ideal platform for implementing Optimal Filtering Algorithm. Actually this algorithm is performing in the DSPs included at ROD Motherboard. This work presents an alternative to implement Optimal Filtering Algorithm.

Arc consistency filtering is widely used in the framework of binary constraint satisfaction problems: with a low complexity, inconsistency may be detected and domains are filtered. In this paper, we show that when detecting inconsistency is the objective, a systematic domain filtering is useless and a lazy approach is more adequate. Whereas usual arc consistency algorithms produce the maximum arc consistent sub-domain, when it exists, we propose a method, called LAC{tau}, which only looks for any arc consistent sub-domain. The algorithm is then extended to provide the additional service of locating one variable with a minimum domain cardinality in the maximum arc consistent sub-domain, without necessarily computing all domain sizes. Finally, we compare traditional AC enforcing and lazy AC enforcing using several benchmark problems, both randomly generated CSP and real life problems.

Atomic line filters have been suggested to be attractive in areas of Doppler velocimetry, resonance fluorescence detection, and resonance ionization detection. They are based on the resonant absorption of photons by an atomic vapor, and allow all other radiation to pass. This allows the detection of very low levels of light superimposed on a large optical background. Several elements have been studied for use as atomic line filters, such as the alkali metals, alkaline earths, and thallium. As previously recognized, thallium is especially attractive since the 535.046 nm metastable transition overlaps with the second harmonic output of an Nd:La2Be2O 5 (BEL) laser (1070 nm). This makes thallium ideal for certain applications as an atomic line filter. Recently a see-through hollow cathode lamp, or galvatron (Hamamatsu), was made commercially available. The galvatron geometry is unique compared to traditional hollow cathode lamps since the cathode and cell are oriented in a T-shape, with the cathode bored completely through to allow the propagation of a light source through the cathode. This allows multi-step excitation of the atomic vapor, not easily accomplished with a traditional hollow cathode lamp. The advantages that a galvatron offers over conventional atomic reservoirs make it an attractive candidate for the application as an atomic line filter; however, little spectroscopic data have been found in the literature. For this reason, Doppler temperatures, number densities, quantum efficiencies, and lifetimes have been determined in order to characterize this atomic reservoir as a potential atomic line filter. These parameters are determined by use of various spectroscopic techniques which include emission, absorption, time-resolved fluorescence, and time-resolved laser-induced saturated fluorescence spectroscopy. From these measurements, it has been demonstrated that a galvatron is an attractive atomic reservoir for applications as an atomic line filter. The spectral resolution of this atomic line filter was found to be superior to that of a traditional hollow cathode lamp and electrodeless discharge lamp. A desired number density can be rapidly produced by applying the appropriate current and can be reproduced from one experiment to the next. In addition, the quantum efficiency of this system was found to be limited only by the competing radiative pathways of the particular energy level arrangement which allows it to be a very efficient detector. This system has the potential to be simple, compact, and portable which makes it an ideal atomic line filter.

Computed Tomography (CT) is a well established technique, particularly in medical imaging, but also applied in Synthetic Aperture Radar (SAR) imaging. Basic CT imaging via back-projection is treated in many texts, but often with insufficient detail to appreciate subtleties such as the role of non-uniform sampling densities. Herein are given some details often neglected in many texts.

The infection curve of Severe Acute Respiratory Syndrome (SARS) using the back-projection method was reconstructed for the SARS outbreak period (from March 1, 2003 to June 20, 2003) in Beijing to assess the effectiveness of the intervention measures. There were 2,521 confirmed SARS cases with a popu...

Recent soft shadow mapping techniques based on back-projection can render high quality soft shadows in real time. However, real time high quality rendering of large penumbrae is still challenging, especially when multi-layer shadow maps are used to reduce single light sample silhouette artifact. In ...

The functionality of dissolved organic matter (DOM) was studied by assessing the availability of polycyclic aromatic hydrocarbons (PAHs) spiked in pore water samples separated from sediments by water extraction and centrifugation with or without subsequent filtration. The purpose was to compare the effects of traditionally defined DOM (0.45-?m cut off) and larger colloidal material present in the separated pore water samples on the partitioning and bioavailability of PAHs. The tested PAHs included phenanthrene (Phe), fluoranthene (Flu), pyrene (Pyr) and benzo[a]pyrene (BaP). Bioavailability of the selected PAHs was tested with two ecologically different organisms: pelagic filter feeder Daphnia magna and sediment-dwelling deposit feeder Lumbriculus variegatus. Sorption to DOM (i.e. in filtered samples) was clearly higher for BaP than for the other PAH. This was also reflected in significantly reduced bioavailability for both model organisms in the filtered samples compared to DOM-free conditions. For the other PAHs the sorption was significant only in the unfiltered samples indicating the importance of larger colloidal material. Thus, the bioavailability of PAHs was also more effectively reduced by the colloidal material. This holds true for both the model organisms, indicating that the ecological differences i.e. filter feeder vs. deposit feeder do not affect in this respect. It appears that considering only traditionally defined DOM, material that may be present in environmental samples and is important for the speciation and bioavailability of contaminants is ignored. PMID:22136915

The level of serotonin was regulated by serotonin transporter (SERT), which is a decisive protein in regulation of serotonin neurotransmission system. Many psychiatric disorders and therapies were also related to concentration of cerebral serotonin. I-123 ADAM was the novel radiopharmaceutical to image SERT in brain. The aim of this study was to measure reliability of SERT densities of healthy volunteers by automated anatomical labeling (AAL) method. Furthermore, we also used statistic parametric mapping (SPM) on a voxel by voxel analysis to find difference of cortex between test and retest of I-123 ADAM single photon emission computed tomography (SPECT) images. Twenty-one healthy volunteers were scanned twice with SPECT at 4 h after intravenous administration of 185 MBq of {sup 123}I-ADAM. The image matrix size was 128x128 and pixel size was 3.9 mm. All images were obtained through filtered back-projection (FBP) reconstruction algorithm. Region of interest (ROI) definition was performed based on the AAL brain template in PMOD version 2.95 software package. ROI demarcations were placed on midbrain, pons, striatum, and cerebellum. All images were spatially normalized to the SPECT MNI (Montreal Neurological Institute) templates supplied with SPM2. And each image was transformed into standard stereotactic space, which was matched to the Talairach and Tournoux atlas. Then differences across scans were statistically estimated on a voxel by voxel analysis using paired t-test (population main effect: 2 cond's, 1 scan/cond.), which was applied to compare concentration of SERT between the test and retest cerebral scans. The average of specific uptake ratio (SUR: target/cerebellum-1) of {sup 123}I-ADAM binding to SERT in midbrain was 1.78{+-}0.27, pons was 1.21{+-}0.53, and striatum was 0.79{+-}0.13. The cronbach's {alpha} of intra-class correlation coefficient (ICC) was 0.92. Besides, there was also no significant statistical finding in cerebral area using SPM2 analysis. This finding might help us to understand reliability of I-123 ADAM SPECT imaging and further develop new strategy for the treatment of psychiatric disorders.

Purpose: To evaluate the performance of computed tomographic (CT) examinations at 80 and 100 kV with tube current-time products of 75-150 mA and the effect of adaptive statistical iterative reconstruction (ASIR) on CT image quality in patients with urinary stone disease. Materials and Methods: In this HIPAA-compliant institutional review board-approved study, verbal consent for prospective low-dose CT and waivers of consent for retrospective review of CT scans were obtained. Between November 2010 and April 2011, 25 patients (15 men, 10 women; mean age, 35 years) with urolithiasis underwent 64-section multidetector CT with 75-150 mA and noise index of 30. Modified protocol was based on body weight (200 lb [90 kg], 100 kV). Images of 5-mm section thickness were reconstructed with filtered back projection (FBP) and 60% and 80% ASIR techniques, with 3-mm coronal and sagittal reformations. Two readers independently reviewed FBP and ASIR data sets for image quality (scale, 1-5), noise (scale , 1-3), and calculi (number, size, location). Confidence levels for urolithiaisis and alternate diagnoses were rated (scale, 1-3). In 13 patients, FBP CT images acquired with the reference standard departmental protocol were available for comparison. Radiation dose was compared between imaging series. Statistical analysis was performed with Wilcoxon signed rank and paired t tests. Results: Modified-protocol FBP images showed low image quality (score, 2.5), with improvement on modified-protocol ASIR images (score, 3.4) (P = .03). All 33 stones (mean diameter, 6.1 mm; range, 2-28 mm) at modified-protocol CT were diagnosed by both readers. In 20 of 25 patients (80%), ASIR images were rated adequate for rendering other diagnoses in the abdomen (score, 2.0), as opposed to FBP images (score, 1.3). Mean radiation dose for modified-protocol CT was 1.8 mGy (1.3 mGy for patients 200 lb) in comparison with 9.9 mGy for reference-protocol CT (P = .001). Conclusion: Image quality improvements with ASIR at reduced radiation dose of 1.8 mGy enabled effective evaluation of urinary calculi without substantially affecting diagnostic confidence. © RSNA, 2012. PMID:22891359

This study examined the impact of collaborative filtering (the so-called recommender) on college students' use of an online forum for English learning. The forum was created with an open-source software, Drupal, and its extended recommender module. This study was guided by three main questions: 1) Is there any difference in online behaviors between students who use a traditional forum and students who use a forum with a recommender?; 2) Is there any difference in learning motivation between students who use a traditional forum and students who use a forum with a recommender?; 3) Is there any difference in learning achievement between students who use a traditional forum and students who use a forum with a recommender?. This study was a one-way quasi-experimental design where the independen...

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.

This thesis deals with the problem of fusing and managing data concerning the state or identity of a given object. Focus is put on the challenges occurring within the field of mobile robot navigation. The main problem here will often be to keep track of the position and orientation of the robot within some global frame of reference using a wide variety of sensors providing odometric, inertial and absolute data concerning the robot and its surroundings. Kalman filters have for a long time been widely used to solve this problem. However, when measurements are delayed or the mobile robot is inaccurately modelled some interesting problems arise. In the thesis different filter designs are evaluated and compared. A new method for dealing with delayed measurements by extrapolating these through the delay period is introduced and an augmented filter is developed that can reduce the effect of modelling errors due to inaccurately known system parameters. Further, a new method for determining the process noise matrix for Kalman filters on mobile robots is introduced and shown to be more robust towards modelling uncertainties than traditional methods. The method is based on the assumption that modelling errors constitute the most significant error source in the filter and requires a rough estimate of the size of the errors.

The presence of non-metallic inclusions in aluminum billets can significantly affect both plastic deformation during the extrusion process and final surface quality. Traditionally, secondary extrusion billet casters have relied on a combination of furnace fluxing and a ceramic foam filter to obtain the required melt cleanliness. Ever increasing demands to obtain better extrusion surface quality and more complex shapes with reduced press cycle times, has led to a trend toward the use of finer pore ceramic foam filters. A dual stage filter bowl and preheat system has been developed which allows routine use of 50 ppi ceramic foam to filter metal produced from remelt scrap without the use of an in-line spinning nozzle degasser system. Improved metal cleanliness was quantified by taking LAIS inclusion samples prior to and after the installation of a dual stage filtration system. Overall, the filtration efficiency improved from 45--51% with a standard single stage ceramic foam filtration system to 85% with a dual stage system utilizing a 30 ppi/50 ppi filter pore size combination. Analysis of press cycle times indicated an overall reduction of 11.4% with AA 6061 billets. A 4.8% increase in extrusion press speed was realized with AA 7129 billets.

We report the first results of ultra-low frequency Stokes and anti-Stokes Raman spectra at 785nm showing clearly resolved frequency shifts down to 10cm-1 from the excitation line, using commercially available ultra-narrow band notch and ASE suppression filters, and a single stage spectrometer. Near infra-red (NIR) wavelengths are of particular interest for Raman spectroscopy due to the reduced fluorescence observed for most materials. Previously reported attempts to produce ultra-low frequency Raman spectra at 785nm with volume holographic notch filters were largely unsuccessful, due to the fact that these ultra-narrow line notch filters and the wavelength of the laser must be very well matched to be effective. Otherwise, if the filters have any manufacturing errors or the laser wavelength is unstable, insufficient suppression of the Rayleigh scattered light will allow it to overwhelm the Raman signal. Recent improvements in both notch and ASE filters, wavelength-stabilized lasers, and optical system design have enabled low-frequency Raman spectra to be successfully taken at 785nm for several typical materials. Two ultra-narrow line notch filters formed as volume holographic gratings (VHGs) in glass with individually measured optical densities of 4.5 were used to block the Rayleigh scattered light from a matched VHG wavelength stabilized laser. Five discrete peaks below 100cm-1 were simultaneously observed for sulfur in both the Stokes and anti-Stokes regions at 28, 44, 52, 62, and 83cm-1. With no degradation in filter performance over time and extremely narrow spectral transition widths of less than 10cm-1, this relatively simple system is able to make ultra-low frequency Stokes and anti-Stokes Raman measurements at a fraction of the size and cost of traditional triple monochromator systems.

Symmetrical phase-only filtering (SPOF) can be exploited to obtain substantial improvements in the results of data processing in particle-image velocimetry (PIV). In comparison with traditional PIV data processing, SPOF PIV data processing yields narrower and larger amplitude correlation peaks, thereby providing more-accurate velocity estimates. The higher signal-to-noise ratios associated with the higher amplitude correlation peaks afford greater robustness and reliability of processing. SPOF also affords superior performance in the presence of surface flare light and/or background light. SPOF algorithms can readily be incorporated into pre-existing algorithms used to process digitized image data in PIV, without significantly increasing processing times. A summary of PIV and traditional PIV data processing is prerequisite to a meaningful description of SPOF PIV processing. In PIV, a pulsed laser is used to illuminate a substantially planar region of a flowing fluid in which particles are entrained. An electronic camera records digital images of the particles at two instants of time. The components of velocity of the fluid in the illuminated plane can be obtained by determining the displacements of particles between the two illumination pulses. The objective in PIV data processing is to compute the particle displacements from the digital image data. In traditional PIV data processing, to which the present innovation applies, the two images are divided into a grid of subregions and the displacements determined from cross-correlations between the corresponding sub-regions in the first and second images. The cross-correlation process begins with the calculation of the Fourier transforms (or fast Fourier transforms) of the subregion portions of the images. The Fourier transforms from the corresponding subregions are multiplied, and this product is inverse Fourier transformed, yielding the cross-correlation intensity distribution. The average displacement of the particles across a subregion results in a displacement of the correlation peak from the center of the correlation plane. The velocity is then computed from the displacement of the correlation peak and the time between the recording of the two images. The process as described thus far is performed for all the subregions. The resulting set of velocities in grid cells amounts to a velocity vector map of the flow field recorded on the image plane. In traditional PIV processing, surface flare light and bright background light give rise to a large, broad correlation peak, at the center of the correlation plane, that can overwhelm the true particle- displacement correlation peak. This has made it necessary to resort to tedious image-masking and background-subtraction procedures to recover the relatively small amplitude particle-displacement correlation peak. SPOF is a variant of phase-only filtering (POF), which, in turn, is a variant of matched spatial filtering (MSF). In MSF, one projects a first image (denoted the input image) onto a second image (denoted the filter) as part of a computation to determine how much and what part of the filter is present in the input image. MSF is equivalent to cross-correlation. In POF, the frequency-domain content of the MSF filter is modified to produce a unitamplitude (phase-only) object. POF is implemented by normalizing the Fourier transform of the filter by its magnitude. The advantage of POFs is that they yield correlation peaks that are sharper and have higher signal-to-noise ratios than those obtained through traditional MSF. In the SPOF, these benefits of POF can be extended to PIV data processing. The SPOF yields even better performance than the POF approach, which is uniquely applicable to PIV type image data. In SPOF as now applied to PIV data processing, a subregion of the first image is treated as the input image and the corresponding subregion of the second image is treated as the filter. The Fourier transforms from both the firs and second- image subregions are normalized by the square roots of their respective magnitudes.

Traditional LC filters can't work stably in small rating stand-alone power grid. So active power filter (APF) is becoming an important tool to solve the power quality problem in small rating stand-alone power grid. In most current detection algorithm of APF, it needs a synchronizing signal. Firstly, the influence of the synchronizing signal error on current detection of APF is analyzed in this paper. Voltage distortion, voltage unbalance and frequency fluctuation are frequent and severe in small rating stand-alone power grids, so traditional synchronizing signal obtaining method--phase locking based on zero-cross detection can't work effectively in small rating stand-alone power grid. Then a soft phase locked loop with additional filter is proposed. It can lock the phase angle on to the positive sequence of fundamental voltage accurately and rapidly. It ensures the performance of APF applied in the small rating stand-alone power grid. Moreover, the soft phase locked loop is easy to be implemented in a DigitalSignal Processor (DSP). Simulation and experimental results validate that the soft phase locked loop has satisfactory performance.

In this paper we propose a framework for both gradient descent image and object alignment in the Fourier domain. Our method centers upon the classical Lucas & Kanade (LK) algorithm where we represent the source and template/model in the complex 2D Fourier domain rather than in the spatial 2D domain. We refer to our approach as the Fourier LK (FLK) algorithm. The FLK formulation is advantageous when one pre-processes the source image and template/model with a bank of filters (e.g. oriented edges, Gabor, etc.) as: (i) it can handle substantial illumination variations, (ii) the inefficient pre-processing filter bank step can be subsumed within the FLK algorithm as a sparse diagonal weighting matrix, (iii) unlike traditional LK the computational cost is invariant to the number of filters and as a result far more efficient, and (iv) this approach can be extended to the inverse compositional form of the LK algorithm where nearly all steps (including Fourier transform and filter bank pre-processing) can be pre-computed leading to an extremely efficient and robust approach to gradient descent image matching. Further, these computational savings translate to non-rigid object alignment tasks that are considered extensions of the LK algorithm such as those found in Active Appearance Models (AAMs). PMID:23045367

We propose a new technique of measuring user similarity in collaborative filtering using electric circuit analysis. Electric circuit analysis is used to measure the potential differences between nodes on an electric circuit. In this paper, by applying this method to transaction networks comprising users and items, i.e., user–item matrix, and by using the full information about the relationship structure of users in the perspective of item adoption, we overcome the limitations of one-to-one similarity calculation approach, such as the Pearson correlation, Tanimoto coefficient, and Hamming distance, in collaborative filtering. We found that electric circuit analysis can be successfully incorporated into recommender systems and has the potential to significantly enhance predictability, especially when combined with user-based collaborative filtering. We also propose four types of hybrid algorithms that combine the Pearson correlation method and electric circuit analysis. One of the algorithms exceeds the performance of the traditional collaborative filtering by 37.5% at most. This work opens new opportunities for interdisciplinary research between physics and computer science and the development of new recommendation systems PMID:22096188

We estimated the source rupture of the 2008 Wenchuan Earthquake (Ms 8), China, based on a back-projection of seismic waves to their source plane, using data from regional broadband arrays in Taiwan and northern Vietnam. Observations from these arrays, located at different azimuths, were processed to evaluate the spatio-temporal rupture behavior of the fault. The seismic energy spot converted from windowed array waveforms was back-projected to the rupture plane of the earthquake, to image the instantaneous slip on the fault plane. Rupture processes were reconstructed based on the imaged time-dependent seismic energy radiating from the earthquake fault plane. The high station density of both arrays enabled a detailed examination of the rupture processes. The results indicate that the 2008 We...

Background: Infection with human cytomegalovirus (HCMV) is the most common congenital virus infection, affecting about 0.5-2% of newborns. Using DBS on Guthrie cards, it is possible to discriminate congenital from postnatal HCMV-infection. However, a recent European trial revealed serious problems in detection of low HCMV-DNA levels from DBS-filter-cards (Barbi et al., 2008).^7 Objectives: Evaluation of the most sensitive combination of sample size, DNA extraction method and PCR system for the detection of low copy numbers of HCMV-DNA from DBS-filter-cards. Study design: We compared three different manual extraction methods for the detection of HCMV-DNA out of DBS: the QIAmp-blood-Mini-Kit, a heat-extraction-method and traditional phenol-chloroform extraction. Additionally, we tested an au...

The design of spiral systolic arrays (Sas) with asynchronous controls for efficient and flexible implementation of linear phase FIR filters is presented. In this approach, (1) reduction of filter due to symmetry, (2) conversion of sequential input signal into input blocks by means of a spiral systolic mesh that is (a) suitable for highly parallel processing and (b) flexible for enabling various array sizes, and (3) making data streams independent of computations executed in each processor will collectively minimize computation time. The SA architecture processes the input signal row by row, and eliminates the complex shift register organization of the traditional FIR realization. Incorporated in this design are maximum parallelism and pipelinability, trade-off among computations, communications, and memory. Moreover, the systolic array will use simple local interconnection without undesirable properties such as preloading input data or global broadcasting. The key component of the asynchronous spiral SA is a communication protocol that controls input data flow properly and efficiently.

Skin detection has been considered as the principal step in many machine vision systems, such as face detection and adult image filtering. Among all these techniques, skin color is the most welcome cue because of its robustness. However, traditional color-based approaches poorly perform on the classification of skin-like pixels. In this paper, we propose a new skin detection method based on the cascaded adaptive boosting (AdaBoost) classifier, which consists of minimum-risk based Bayesian classifier and models in different color spaces such as HSV (hue-saturation-value), YCgCb (brightness-green-blue) and YCgCr (brightness-green-red). In addition, we have constructed our own database that is larger and more suitable for training and testing on filtering adult images than the Compaq data set...

The motivation of this paper is to investigate the use of a Neural Network (NN) architecture, the Psi Sigma Neural Network (PSN), when applied to the task of forecasting and trading the Euro/Dollar (EUR/USD) exchange rate using the European Central Bank (ECB) fixing series and to explore the utility of Kalman Filters in combining NN forecasts. This is done by benchmarking the statistical and trading performance of PSN with a Naive Strategy, an Autoregressive Moving Average (ARMA) model and two different NN architectures, a Multi-Layer Perceptron (MLP) and a Recurrent Network (RNN). We combine our NN forecasts with Kalman Filter, a traditional Simple Average, the Bayesian Average, the Granger-Ramanathan's Regression Approach (GRR) and the Least Absolute Shrinkage and Selection Operator (LAS...

Abstract Benefitting from its ability to estimate the target state's posterior probability density function (PDF) in complex nonlinear and non-Gaussian circumstance, particle filter (PF) is widely used to solve the target tracking problem in wireless sensor networks. However, the traditional PF algorithm based on sequential importance sampling with re-sampling will degenerate if the latest observation appear in the tail of the prior PDF or if the observation likelihood is too peaked in comparison with the prior. In this paper, we propose an improved particle filter which makes full use of the latest observation in constructing the proposal distribution. The quality prediction function is proposed to measure the quality of the particles, and only the high quality particles are selected and ...

Traditionally, mid infrared detection has been performed using black body sources and filters. With the availability of infrared LEDs, which emit between the 2 - 5 micrometers wavelength, solid state gas cells can be designed which eliminate the broad spectrum problem of black body source and allow ac signal detection without mechanical chopper wheels. Dedicated microprocessors also allow other advantages, including over-sampling and, in certain applications, emitter low power mode to reduce power consumption. Results are shown for gas cells to detect carbon dioxide and hydrocarbons. LED optical gas cells are applicable to systems that require low power drain, small size, log-term stability and/or fast warm up time. Laser Monitoring Systems Ltd has developed a family of infrared LEDs with narrower optical bandwidth that can be optically modulated by electrical pulses. These infrared LEDs can thus replace the thermal source, bandpass filters and chopper wheel of the conventional monitor, giving a solid state, lower powered, fast response and contact instrument.

Digital scan conversion algorithm is the most computational intensive part of B-mode ultrasound imaging. Traditionally, in order to meet the requirements of real-time imaging, digital scan conversion algorithm often traded off image quality for speed, such as the use of simple image interpolation algorithm, the use of look-up table to carry out polar coordinates transform and logarithmic compression. This paper presents a GPU-based high-definition real-time ultrasound digital scan conversion algorithm implementation. By rendering appropriate proxy geometry, we can implement a high precision digital scan conversion pipeline, including polar coordinates transform, bi-cubic image interpolation, high dynamic range tone reduction, line average and frame persistence FIR filtering, 2D post filtering, fully in the fragment shader of GPU at real-time speed. The proposed method shows the possibility of updating exist FPGA or ASIC based digital scan conversion implementation to low cost GPU based high-definition digital scan conversion implementation.

We designed a universal digital energy spectroscopy based on online digital signal processing. A prototype system was built and tested. Signals from radiation detectors were processed via a digital filter whose coefficients could be modified without changing the hardware. The paper introduces the hardware design of the digital energy spectroscopy system as well as the full set of software consisting of the selection of the coefficients of the finite impulse response (FIR) filter and the coding in the field-programmable gate array (FPGA). The system was tested with the high purity germanium (HPGe) detector. The results showed that this prototype can achieve an energy resolution close to that of a traditional multi-channel analyzer (MCA) with a much higher counting rate.

One of the major issues with multi-carrier systems is their vulnerability to timing synchronization errors resulting in the loss of time synchronization which causes loss of orientation of incoming data at the receiver. This paper presents an acquisition algorithm to timing recovery using the decision-aided extended Kalman filtering (EKF) technique for nonlinear disturbance channels in a wavelet packet transform-based multicarrier modulation communication system. This timing recovery algorithm gives faster convergence, smaller root mean square (RMS) errors, and better bit error rate (BER) performance than traditional timing recovery methods, such as the phase-locked loop (PLL), maximum likelihood (ML), and Kalman filter (KF) methods. Thus, the algorithm is able to handle larger timing erro...

In this paper, a CMOS implementation of a fully differential current-mode operational amplifier (COA) is presented. To achieve very low input resistance, a new technique based on a positive feedback is used in the input transimpedance stage. Additionally, traditional current output stage (Arbel Goldminz output stage) with improved output resistance is selected as a transconductance stage. Results of simulations exhibit 96dB DC gain, nearly Formula Not Shown input, Formula Not Shown output resistances and a gain-bandwidth product exceeding 90MHz. The proposed COA is operated under Formula Not Shown voltage supplies and designed with Formula Not Shown CMOS process. Furthermore, COA-based fourth-order band-pass (BP) filter consisting of Butterworth low-pass (LP) and high-pass (HP) filters is ...

Over the last years, the ensemble Kalman filter (EnKF) has become a very popular tool for history matching petroleum reservoirs. EnKF is an alternative to more traditional history matching techniques as it is computationally fast and easy to implement. Instead of seeking one best model estimate, EnKF is a Monte Carlo method that represents the solution with an ensemble of state vectors. Lately, several ensemble-based methods have been proposed to improve upon the solution produced by EnKF. In this paper, we compare EnKF with one of the most recently proposed methods, the adaptive Gaussian mixture filter (AGM), on a 2D synthetic reservoir and the Punq-S3 test case. AGM was introduced to loosen up the requirement of a Gaussian prior distribution as implicitly formulated in EnKF. By combining...

The use of electronic portal imaging devices (EPIDs) is a promising method for the dosimetric verification of external beam, megavoltage radiation therapy--both pretreatment and in vivo. In this study, a previously developed EPID back-projection algorithm was modified for IMRT techniques and applied to an amorphous silicon EPID. By using this back-projection algorithm, two-dimensional dose distributions inside a phantom or patient are reconstructed from portal images. The model requires the primary dose component at the position of the EPID. A parametrized description of the lateral scatter within the imager was obtained from measurements with an ionization chamber in a miniphantom. In addition to point dose measurements on the central axis of square fields of different size, we also used dose profiles of those fields as reference input data for our model. This yielded a better description of the lateral scatter within the EPID, which resulted in a higher accuracy in the back-projected, two-dimensional dose distributions. The accuracy of our approach was tested for pretreatment verification of a five-field IMRT plan for the treatment of prostate cancer. Each field had between six and eight segments and was evaluated by comparing the back-projected, two-dimensional EPID dose distribution with a film measurement inside a homogeneous slab phantom. For this purpose, the {gamma}-evaluation method was used with a dose-difference criterion of 2% of dose maximum and a distance-to-agreement criterion of 2 mm. Excellent agreement was found between EPID and film measurements for each field, both in the central part of the beam and in the penumbra and low-dose regions. It can be concluded that our modified algorithm is able to accurately predict the dose in the midplane of a homogeneous slab phantom. For pretreatment IMRT plan verification, EPID dosimetry is a reliable and potentially fast tool to check the absolute dose in two dimensions inside a phantom for individual IMRT fields. Film measurements inside a phantom can therefore be replaced by EPID measurements.

This paper describes a nine-dimensional extended Kalman filter (EKF) to jointly track and discriminate exoatmospheric active decoys in real time using motion features. By introducing an auxiliary variable as relative range delay ratio (RRDR), explicit nonlinear motion model of decoys in the East-North-Up coordinate system (ENU-CS) and the Jacobian matrix needed for the EKF are derived. The discrimination is then implemented according to the estimated deception range and its associated variance. The discrimination performance and the tracking accuracy compared to the traditional six-dimensional EKF are evaluated by Monte Carlo simulations. The advantage of the new algorithm lies in its real-time integration of tracking and discrimination.

We study the effect of filter zero-point uncertainties on future supernova dark energy missions. Fitting for calibration parameters using simultaneous analysis of all Type Ia supernova standard candles achieves a significant improvement over more traditional fit methods. This conclusion is robust under diverse experimental configurations (number of observed supernovae, maximum survey redshift, inclusion of additional systematics). This approach to supernova fitting considerably eases otherwise stringent mission calibration requirements. As an example we simulate a space-based mission based on the proposed JDEM satellite; however the method and conclusions are general and valid for any future supernova dark energy mission, ground or space-based.

A filter-based algorithm for estimating the ionosphere error of the GNSS signals in the differential system is proposed in the paper. Based on the slow-varying characteristic of the ionosphere delay, the historical ionosphere delay data is involved in the algorithm. The measurement model is constructed according to the Grid Interpolation Model (GIM).The relevant analysis is conducted by the simulation and the corresponding results indicated that comparing with the traditional method, at least 60% promotion on the accuracy has been accomplished so that the algorithm in this paper can provide a more accurate estimation of the ionosphere error for GNSS signals.   

The AMBUR (Analyzing Moving Boundaries Using R) package for the R software environment provides a collection of functions for assisting with analyzing and visualizing historical shoreline change. The package allows import and export of geospatial data in ESRI shapefile format, which is compatible with most commercial and open-source GIS software. The ''baseline and transect'' method is the primary technique used to quantify distances and rates of shoreline movement, and to detect classification changes across time. Along with the traditional ''perpendicular'' transect method, two new transect methods, ''near'' and ''filtered,'' assist with quantifying changes along curved shorelines that are problematic for perpendicular transect methods. Output from the analyses includes data tables, grap...

In order to overcome the limitations of piecewise constant phenomenon and computational burden which exist in Markov Random Field (MRF) with pair wise neighborhood and traditional learning style respectively, this paper proposes a clustering learning method from natural image database, no filters included. By this method, we get the distributive law of the blocks abstracted from natural images. Furthermore, we also do the prior image modeling according to the learned law. And the real application in image restoration illustrates its effectiveness by comparison between high order MRF prior model and pair wise MRF prior model.

Minimum symbol error rate detection in Single-Input Multiple- Output(SIMO) channels with Markov noise is presented. The special case of zero-mean Gauss-Markov noise is examined closer as it only requires knowledge of the second-order moments. In this special case, it is shown that optimal detection can be achieved by a Multiple-Input Multiple- Output(MIMO) whitening filter followed by a traditional BCJR algorithm. The Gauss-Markov noise model provides a reasonable approximation for co-channel interference, making it an interesting single-user detector for many multiuser communication systems where interference from other transmitters has a limiting effect.

In power system, capacitors are widely used to compensate reactive power, which generally cause resonance problems in harmonic distorted network. In this paper, A method of using a parallel active power filter (PAPF) to damp the resonances is proposed. The proposed method is compound with traditional method, it shows that whether the capacitor current is included in the detecting current of PAPF or not. Also the PAPF with proposed method has strong ability in harmonic compensation. Finally, the experiment results are presented to verify the analysis.

A system has been developed that establishes a standardized cartographic database for each of the 19 planets and major satellites that have been explored to date. Compilation of the databases involves both traditional and newly developed digital image processing and mosaicking techniques, including radiometric and geometric corrections of the images. Each database, or digital image model (DIM), is a digital mosaic of spacecraft images that have been radiometrically and geometrically corrected and photometrically modeled. During compilation, ancillary data files such as radiometric calibrations and refined photometric values for all camera lens and filter combinations and refined camera-orientation matrices for all images used in the mapping are produced.

Traditional methods for the shape-forming of engineering ceramics entail plastic deformation of powder slurries containing hazardous organic liquids as suspending media. Replacing these organics with aqueous media requires the development of environmentally-benign, water-soluble additives which serve as plasticizers and binders. Fundamental studies were performed with aqueous suspensions of colloidal {alpha}-Al{sub 2}O{sub 3} to evaluate the role of sucrose, maltodextrin, and oxalic acid on viscosity, sedimentation and filtration characteristics, plastic flow behavior of filter cakes, and sinterability. Maltodextrin and oxalic acid systems exhibited superior results, including filtration to high packing-densities and clay-like plasticity with minimal cracking.

It is not uncommon for remote sensing systems to produce in excess of 100 Mbytes/sec. Los Alamos National Laboratory designed a reconfigurable computer to tackle the signal and image processing challenges of high bandwidth sensors. Reconfigurable computing, based on field programmable gate arrays, offers ten to one hundred times the performance of traditional microprocessors for certain algorithms. This paper discusses the architecture of the computer and the source of performance gains, as well as an example application. The calculation of multiple matched filters applied to multispectral imagery, showing a performance advantage of forty-five over Pentium II (450 MHz), is presented as an exemplar of algorithms appropriate for this technology.

A methodology for generating optimal sensor network design for multirate systems is presented. Location of sensors, cost of measurement and frequency of sampling are important factors that have been incorporated in the sensor network design formulation. The proposed methodology is based on evaluating trade-off (Pareto optimal) solutions between the quality of state estimation and the total measurement cost associated with the sensor network. To accommodate different sampling frequencies and evaluate their effect on state estimation accuracy, a generic multirate extension of the traditional Kalman filter is used. In general, higher accuracies of the state estimates are realizable at expense of higher measurement cost. Incorporation of these conflicting objectives of minimizing measurement c...

Better mobile computing, broadband and devices have contributed to the fast growth and popularity of massively multiplayer online games (MMOGs). Players are now expecting a more personalised gaming experience as personalisation has begun to filter into most games and not just MMOGs. In this paper, we explain how players of MMOGs can enjoy a ubiquitous and personalised gaming experience anywhere, on any device, and on any network with Artemis. MPEG-7 is not traditionally used for modelling games; however, Artemis adopts MPEG-7 for modelling the player, their device and the game, in conjunction with genetic algorithms for personalising the game, where possible.

Traditional parameters, i.e., neutron flux, cadmium ratio, neutron-to-gamma ratio and a geometrical parameter have been used to characterize neutron radiography facilities. The parameters will be reconsidered as a point of view how to get a neutron beam with a high quality to obtain the best image. Usefulness of filter effects will be also discussed to enhance the validity of the neutron radiography (NR) facility. A new parameter, figure of merit F, has been proposed as a measure of geometric effectiveness of the facility. (J.P.N.)

Sparse microwave imaging is a novel radar framework aiming to bring revolutions to the microwave imaging according to the theory of sparse signal processing. As compressive sensing (CS) is introduced to synthetic aperture radar (SAR) imaging in recent years, the current SAR sparse imaging methods have shown their advantages over the traditional matched filtering methods. However, the requirement for these methods to process the compressed range data results in the increase of the hardware complexity. So the SAR sparse imaging method that directly uses the raw data is needed. This paper describes the method of SAR sparse imaging with raw data directly, presents the analysis of the signal-to-noise ratio (SNR) in the echo signal by combining the traditional radar equation with the compressive...

Traditional approaches for gene mapping from candidate gene studies to positional cloning strategies have been applied for Mendelian disorders. Since 2005, next-generation sequencing (NGS) technologies are improving as rapid, high-throughput and cost-effective approaches to fulfill medical sciences and research demands. Using NGS, the underlying causative genes are directly distinguished via a systematic filtering, in which the identified gene variants are checked for novelty and functionality. During the past 2 years, the role of more than 100 genes has been distinguished in rare Mendelian disorders by means of whole-exome sequencing (WES). Combination of WES with traditional approaches, consistent with linkage analysis, has had the greatest impact on those disorders following autosomal m...

Purpose - As international users increase rapidly, multilingual systems have become a very important service for global users. The purpose of this paper is to design and implement an ontology-driven medical information retrieval (OMIR) system by building a medical ontology based on the Centers for Disease Control and Prevention's (CDC) medical records. Design/methodology/approach - A traditional cataloging scheme is used as a navigation menu in the CDC system. This traditional cataloging scheme is transformed to a unique medical ontology for global users in the OMIR system. An experimental study was conducted on both an ontology-driven medical information system (OMIR) and the CDC system. Findings - The medical ontology can be used to filter out unsuitable resources based on semantic relat...

The runthru system consists of five programs: workcell filter, just do it, transl8g, decim8, and runthru. The workcell filter program is useful if the source of your 3D triangle mesh model is IGRIP. It will traverse a directory structure of Deneb IGRIP files and filter out any IGRIP part files that are not referenced by an accompanying IGRIP work cell file. The just do it program automates translating and/or filtering of large numbers of parts that are organized in hierarchical directory structures. The transl8g program facilitates the interchange, topology generation, error checking, and enhancement of large 3D triangle meshes. Such data is frequently used to represent conceptual designs, scientific visualization volume modeling, or discrete sample data. Interchange is provided between several popular commercial and defacto standard geometry formats. Error checking is included to identify duplicate and zero area triangles. Model engancement features include common vertex joining, consistent triangle vertex ordering, vertex noemal vector averaging, and triangle strip generation. Many of the traditional O(n2) algorithms required to provide the above features have been recast and are o(nlog(n)) which support large mesh sizes. The decim8 program is based on a data filter algorithm that significantly reduces the number of triangles required to represent 3D models of geometry, scientific visualization results, and discretely sampled data. It eliminates local patches of triangles whose geometries are not appreciably different and replaces them with fewer, larger triangles. The algorithm has been used to reduce triangles in large conceptual design models to facilitate virtual walk throughs and to enable interactive viewing of large 3D iso-surface volume visualizations. The runthru program provides high performance interactive display and manipulation of 3D triangle mesh models.

Purpose: Several investigators have shown that noise equivalent count rate (NECR) is linearly proportional to the square of image signal-to-noise ratio (SNR) when PET images are reconstructed using filtered back-projection. However, to our knowledge, none have shown a similar relationship in fully 3D ordered-subset expectation maximization (OSEM) reconstruction. This paper has two aims. The first is to investigate the NECR-SNR relationship for 3D-OSEM reconstruction using phantom studies while the second aim is to evaluate the NECR-SNR relationship using patient data.Methods: An anthropomorphic phantom was scanned on a GE Discovery-STE (DSTE) PET?CT scanner in 3D mode with an initial activity concentration of 66.34 kBq?cc. PET data were acquired over the lower chest?upper abdomen region in dynamic mode. The experiment was repeated with the same activity concentration on a GE Discovery-RX (DRX) scanner. Care was taken to place the phantom at identical positions in both scanners. PET data were then reconstructed using 3D Reprojection (3D-RP) and 3D-OSEM with different reconstruction parameters and the NECR and SNR for each frame?image were calculated. SNR(2) was then plotted versus the NECR for each scanner, reconstruction method and parameters. In addition, 40 clinical PET?CT studies from the two scanners (20 patients?scanner) were evaluated retrospectively. The patient studies from each scanner were further divided into two subgroups of body mass indices (BMI). Each PET study was acquired in 3D mode and reconstructed using both 3D-OSEM and 3D-RP. The NECR and SNR of the bed position covering the patient liver were calculated for each patient and averaged for each subgroup. Comparisons of the NECR and SNR between scanner types and BMIs were performed using a t-test and a p value less than 0.05 was considered significant.Results: Phantom results showed that SNR(2) versus NECR was linear for 3D-RP reconstruction across all activity concentration on both scanners, as expected. However, when 3D-OSEM was used, this relationship was nonlinear at activity concentrations beyond the peak NECR on both scanners. On the other hand, the plot of SNR(2) versus trues count rate was linear for 3D-OSEM across all activity concentrations on both scanners independent of reconstruction parameters used. In addition, for activity concentrations 0.05), despite having different NECRs. Patient studies showed a statistically significant difference in NECR as well as the SNR for 3D-RP reconstruction between the two scanners. However, no statistically significant difference was found for 3D-OSEM. A statistically significant difference in both NECR and SNR were found between the different BMI subgroups for both 3D-RP and 3D-OSEM reconstructions.Conclusions: For the scanners and reconstruction algorithm used in this study, our results suggest that the image SNR cannot be predicted by the NEC when using 3D-OSEM reconstruction particularly for those clinical applications requiring high activity concentration. Instead, our results suggest that image SNR varies with activity concentration and is dominated by the 3D-OSEM reconstruction algorithm and its associated parameters, while not being affected by the scanner type for the range of activity concentrations usually found in the clinic. PMID:23039628

The effects of auditory frequency selectivity and phase response on masking were studied using harmonic tone complex maskers with a 100-Hz fundamental frequency. Positive and negative Schroeder-phase complexes (m+ and m-), were used as maskers and the signal was a long-duration sinusoid. In the first experiment, thresholds for signal frequencies of 1 and 4 kHz were measured as a function of masker bandwidth and number of components. A large difference in thresholds between the m+ and m- complexes was found only when masker components were presented ipsilateral to the signal over a frequency range wider than the traditional critical band, regardless of the absolute number of components. In the second experiment, frequency selectivity was measured in harmonic tone complexes with fixed or random phases as well as in noise, using a variant of the notched-noise method with a fixed masker level. The data showed that frequency selectivity is not affected by masker type, indicating that the wide listening bandwidth suggested by the first experiment cannot be ascribed to broader effective filters in complex-tone maskers than in noise maskers. The third experiment employed a novel method of measuring frequency selectivity, which has the advantage that the overall level at the input and the output of the auditory filter remains roughly constant across all conditions. The auditory filter bandwidth measured using this method was wider than that measured in the second experiment, but may still be an underestimate, due to the effects of off-frequency listening. The data were modeled using a single-channel model with various initial filters. The main findings from the simulations were: (1) the magnitude response of the Gammatone filter is too narrow to account for the phase effects observed in the data; (2) none of the other filters currently used in auditory models can account for both frequency selectivity and phase effects in masking; (3) the Gammachirp filter can be made to provide a good account of the data by altering its phase response. The final conclusion suggests that masker phase effects can be accounted for with a single-channel model, while still remaining consistent with measures of frequency selectivity: effects that appear to involve broadband processing do not necessarily require across-channel mechanisms. PMID:11572363

In this paper, we proposed a novel entropy-based image watermarking method in wavelet domain. Unlike traditional entropy, we use the normalized energy instead of the probability which is called energy-based entropy (EBE). Based on EBE, the watermark can be embedded robustly and imperceptibly. In our proposed method, the wavelet-trees are grouped into super-trees. Then each super-tree is also divided into five subblocks. According to the watermark bit state, the EBE of each sub-block will be modified respectively. In an experiment, three images (Lenna, Goldhill and Peppers) are chosen for evaluating the performance. The PSNR of these watermarked images are 44.039, 43.51 and 43.67. Compared with Wang et al. [18], it greatly increases the PSNR, by about 5.8, 4.8 and 3.9 dB respectively. For the consideration of the capacity for embedding, the maximum number of watermark bits is also increased. The experimental results show that the proposed entropy-based watermarking method performs well in JPEG compression, filtering (Gaussian filter, median filter and sharpen) and geometrical attacks (pixel shift and rotation). In addition, it is also very robust to against the multiple watermark attack.   

Anisotropic diffusion (AD) has proven to be very effective in the denoising of magnetic resonance (MR) images. The result of AD filtering is highly dependent on several parameters, especially the conductance parameter. However, there is no automatic method to select the optimal parameter values. This paper presents a general strategy for AD filtering of MR images using an automatic parameter selection method. The basic idea is to estimate the parameters through an optimization step on a synthetic image model, which is different from traditional analytical methods. This approach can be easily applied to more sophisticated diffusion models for better denoising results. We conducted a systematic study of parameter selection for the AD filter, including the dynamic parameter decreasing rate, the parameter selection range for different noise levels and the influence of the image contrast on parameter selection. The proposed approach was validated using both simulated and real MR images. The model image generated using our approach was shown to be highly suitable for the purpose of parameter optimization. The results confirm that our method outperforms most state-of-the-art methods in both quantitative measurement and visual evaluation. By testing on real images with different noise levels, we demonstrated that our method is sufficiently general to be applied to a variety of MR images. PMID:22770691

Metal-organic frameworks (MOFs) or porous coordination polymers (PCPs) have become the focus of intense study over the past decade due to their potential for advancing a variety of applications including air purification, gas storage, adsorption separations, catalysis, gas sensing, drug delivery, and so on. These materials have some distinct advantages over traditional porous materials such as the well-defined structures, uniform pore sizes, chemically functionalized sorption sites, and potential for postsynthetic modification, etc. Thus, synthesis and adsorption studies of porous MOFs have increased substantially in recent years. Among various prospective applications, air purification is one of the most immediate concerns, which has urgent requirements to improve current nuclear, biological, and chemical (NBC) filters involving commercial and military purposes. Thus, the major goal of this funded project is to search, synthesize, and test these novel hybrid porous materials for adsorptive removal of toxic industrial chemicals (TICs) and chemical warfare agents (CWAs), and to install the benchmark for new-generation NBC filters. The objective of this study is three-fold: (i) Advance our understanding of coordination chemistry by synthesizing novel MOFs and characterizing these porous coordination polymers; (ii) Evaluate porous MOF materials for gasadsorption applications including CO2 capture, CH4 storage, other light gas adsorption and separations, and examine the chemical and physical properties of these solid adsorbents including thermal stability and heat capacity of MOFs; (iii) Evaluate porous MOF materials for next-generation NBC filter media by adsorption breakthrough measurements of TICs on MOFs, and advance our understanding about structureproperty relationships of these novel adsorbents.

Noise reduction is a crucial step in hyperspectral imagery pre-processing. Based on sensor characteristics, the noise of hyperspectral imagery represents in both spatial and spectral domain. However, most prevailing denosing techniques process the imagery in only one specific domain, which have not utilized multi-domain nature of hyperspectral imagery. In this paper, a new spatial-spectral noise reduction algorithm is proposed, which is based on wavelet analysis and least squares filtering techniques. First, in the spatial domain, a new stationary wavelet shrinking algorithm with improved threshold function is utilized to adjust the noise level band-by-band. This new algorithm uses BayesShrink for threshold estimation, and amends the traditional soft-threshold function by adding shape tuning parameters. Comparing with soft or hard threshold function, the improved one, which is first-order derivable and has a smooth transitional region between noise and signal, could save more details of image edge and weaken Pseudo-Gibbs. Then, in the spectral domain, cubic Savitzky-Golay filter based on least squares method is used to remove spectral noise and artificial noise that may have been introduced in during the spatial denoising. Appropriately selecting the filter window width according to prior knowledge, this algorithm has effective performance in smoothing the spectral curve. The performance of the new algorithm is experimented on a set of Hyperion imageries acquired in 2007. The result shows that the new spatial-spectral denoising algorithm provides more significant signal-to-noise-ratio improvement than traditional spatial or spectral method, while saves the local spectral absorption features better.

In this paper, we present a tuning methodology for a simple offset-free SISO Model Predictive Controller (MPC) based on autoregressive models with exogenous inputs (ARX models). ARX models simplify system identification as they can be identified from data using convex optimization. Furthermore, the proposed controller is simple to tune as it has only one free tuning parameter. These two features are advantageous in predictive process control as they simplify industrial commissioning of MPC. Disturbance rejection and offset-free control is important in industrial process control. To achieve offset-free control in face of unknown disturbances or model-plant mismatch, integrators must be introduced in either the estimator or the regulator. Traditionally, offset-free control is achieved using Brownian disturbance models in the estimator. In this paper we achieve offset-free control by extending the noise model with a filter containing an integrator. This filter is a first order ARMA model. By simulation and analysis, we argue that it is independent of the parameterization of the underlying linear plant; while the tuning of traditional disturbance models is system dependent. Using this insight, we present MPC for SISO systems based on ARX models combined with the first order filter. We derive expressions for the closed-loop variance of the unconstrained MPC based on a state space representation in innovation form and use these expressions to develop a tuning procedure for the regulator. We establish formal equivalence between GPC and state space based off-set free MPC. By simulation we demonstrate this procedure for a third order system. The offset-free ARX MPC demonstrates satisfactory set point tracking and rejection of an unmeasured step disturbance for a simulated furnace with a long time delay.

A current pursuit of the geodetic community is the optimal integration of differential GPS (DGPS) and inertial navigation system (INS) data streams for precise and efficient position and gravity vector surveying. Therein a complete INS and multiple-antenna GPS receiver payload, mounted on a moving platform, is used in conjunction with a network of ground-fixed single antenna GPS receivers. This paper presents a complete, GPS-based, external updating measurement model for the applicable Kalman filter. The model utilizes four external observation types for every GPS satellite in-view: DGPS range differences, single phase differences, and single phase-rate differences; as well as the mobile, multipleantenna GPS receiver's measurement of the errors in the INS's estimate of the phase difference between any two vehicle-borne GPS antennae. Although not widely conveyed in the geodetic world, the inertial navigation community has long known that traditional Kalman filter covariance propagation recurrences are inherently unstable when such highly accurate external updates are repeatedly applied (every 1 second) over long time durations. A hybrid square root covariance/U — D covariance factorization approach is a numerically stable alternative and is reviewed herein. The hybrid makeup of the algorithm is necessitated by the correlated nature of the fourth type of GPS external measurement listed above (each vehicle-borne GPS antenna forms two baselines). Such measurement correlations require a functional transformation of the overall external updating model to permit the multiple updates (simultaneously available at each updating epoch) to be sequentially (and efficiently) processed. An appropriate transformation is given. Stable covariance propagation relationships are presented and the transformed Kalman gain is also furnished and its use in the determination of the externally updated error states is discussed. Specific DGPS/INS instabilities produced by the traditional recurrences are displayed. The stable alternative method requires about 25% more CPU time than the traditional Kalman recurrences. With the ever-increasing computational speeds of microprocessors, this added CPU time is of no real concern.

8. Filter Wheel .......................................................................................................8. Signal Recovery ................................................................................................9. Chopper ...

It cannot be assumed that storage enclosures considered safe for traditionally printed images and documents are suitable for modern, digitally printed materials. In this project, a large variety of digital print types were tested using a modified version of the ISO 18916 Imaging materials-Processed imaging materials-Photographic activity test for enclosure materials standard to assess the risk to digital prints by paper enclosures known to be inert or reactive with traditional photographic prints. The types of enclosures tested included buffered and non-buffered cotton papers, and groundwood paper. In addition, qualitative filter paper that had been wetted and dried with either an acidic or basic solution was also tested to determine the effects of enclosure pH on digitally printed materials. It was determined that, in general, digital prints tended to be less reactive with various enclosure types than traditional prints. Digital prints were most sensitive to paper that contained groundwood. The enclosure reactivity test results were then integrated with previous published work on the tendencies of various enclosure types to abrade, ferrotype, or block to digital prints in order to create a comprehensive set of recommendations for digital print storage enclosures.

Several information organization, access, and filtering systems can benefit from different kind of document representations than those used in traditional Information Retrieval (IR). Topic Detection and Tracking (TDT) is an example of such a domain. In this paper we demonstrate that traditional methods for term weighing do not capture topical information and this leads to inadequate representation of documents for TDT applications. We present various hypotheses regarding the factors that can help in improving the document representation for Story Link Detection (SLD) — a core task of TDT. These hypotheses are tested using various TDT collections. From our experiments and analysis we found that in order to obtain a faithful representation of documents in TDT domain, we not only need to capture a term's importance in traditional IR sense, but also evaluate its topical behavior. Along with defining this behavior, we propose a novel measure that captures a term's importance at the collection level as well as its discriminating power for topics. This new measure leads to a much better document representation as reflected by the significant improvements in the results.   

Symmetrical phase-only filtering (SPOF) can be exploited to obtain substantial improvements in the results of data processing in particle-image velocimetry (PIV). In comparison with traditional PIV data processing, SPOF PIV data processing yields narrower and larger amplitude correlation peaks, thereby providing more-accurate velocity estimates. The higher signal-to-noise ratios associated with the higher amplitude correlation peaks afford greater robustness and reliability of processing. SPOF also affords superior performance in the presence of surface flare light and/or background light. SPOF algorithms can readily be incorporated into pre-existing algorithms used to process digitized image data in PIV, without significantly increasing processing times. A summary of PIV and traditional PIV data processing is prerequisite to a meaningful description of SPOF PIV processing. In PIV, a pulsed laser is used to illuminate a substantially planar region of a flowing fluid in which particles are entrained. An electronic camera records digital images of the particles at two instants of time. The components of velocity of the fluid in the illuminated plane can be obtained by determining the displacements of particles between the two illumination pulses. The objective in PIV data processing is to compute the particle displacements from the digital image data. In traditional PIV data processing, to which the present innovation applies, the two images are divided into a grid of subregions and the displacements determined from cross-correlations between the corresponding sub-regions in the first and second images. The cross-correlation process begins with the calculation of the Fourier transforms (or fast Fourier transforms) of the subregion portions of the images. The Fourier transforms from the corresponding subregions are multiplied, and this product is inverse Fourier transformed, yielding the cross-correlation intensity distribution. The average displacement of the particles across a subregion results in a displacement of the correlation peak from the center of the correlation plane. The velocity is then computed from the displacement of the correlation peak and the time between the recording of the two images. The process as described thus far is performed for all the subregions. The resulting set of velocities in grid cells amounts to a velocity vector map of the flow field recorded on the image plane. In traditional PIV processing, surface flare light and bright background light give rise to a large, broad correlation peak, at the center of the correlation plane, that can overwhelm the true particle- displacement correlation peak. This has made it necessary to resort to tedious image-masking and background-subtraction procedures to recover the relatively small amplitude particle-displacement correlation peak. SPOF is a variant of phase-only filtering (POF), which, in turn, is a variant of matched spatial filtering (MSF). In MSF, one projects a first image (denoted the input image) onto a second image (denoted the filter) as part of a computation to determine how much and what part of the filter is present in the input image. MSF is equivalent to cross-correlation. In POF, the frequency-domain content of the MSF filter is modified to produce a unitamplitude (phase-only) object. POF is implemented by normalizing the Fourier transform of the filter by its magnitude. The advantage of POFs is that they yield correlation peaks that are sharper and have higher signal-to-noise ratios than those obtained through traditional MSF. In the SPOF, these benefits of POF can be extended to PIV data processing. The SPOF yields even better performance than the POF approach, which is uniquely applicable to PIV type image data. In SPOF as now applied to PIV data processing, a subregion of the first image is treated as the input image and the corresponding subregion of the second image is treated as the filter. The Fourier transforms from both the firs and second- image subregions are normalized by the square roots of their respective magnitudes. This scheme yields optimal performance because the amounts of normalization applied to the spatial-frequency contents of the input and filter scenes are just enough to enhance their high-spatial-frequency contents while reducing their spurious low-spatial-frequency content. As a result, in SPOF PIV processing, particle-displacement correlation peaks can readily be detected above spurious background peaks, without need for masking or background subtraction.

A literature study was made, which gives a survey of the state of the art of emergency filters either installed in nuclear power plant, or planned to be installed, including all exhaust air filters for building and room ventilation in nuclear power plant. The following filter types are covered: sand-bed filter, gravel-bed filter, water, gravel beds in water, metal fibre filter, ceramic fibre filter, gravel bed in water with metal fibres, venturi filter, scrubber, tunnels as filters, activated carbon filter, suspended matter filter/HEPA filter, molecular sieve filter. Design and performance of the filter types are explained, and a comparative evaluation is made on the basis of published experimental data as far as these were available, comparing the following items: trapping performance, pressure drop, thermal performance, filtering mechanism, safety/reliability, dimensions/cost. (orig.).

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.

Attenuation of {gamma}-rays within the body has for some time been recognized as one of the major factors affecting emission tomography data. The manner in which it is treated impacts on the accuracy of the reconstruction. An exact treatment of known or estimated attenuation can be formulated for least squares or maximum likelihood solutions by direct inclusion of the attenuation probabilities in the forward/back projections found in typical iterative algorithms. This approach has required ray tracing and summing of the attenuation coefficients along each ray path which is extremely computationally cumbersome. A fast approach to including attenuation in iterative maximum likelihood and least squares algorithms for SPECT is presented.

Crabtree et al. (2004) summarized some key aspects of H2 production and H storage. Elements in compounds necessary for natural H2 production are Mn in MnO (photosynthesis) and Fe in Fe clusters (bacteria). Relevant elements for H2 production and H storage in compounds known from fumarole emissions and/or volcanic ash leachates are: Mn, Fe, Ti, Mg, B, N, Al, Ni, La, K, Na. H2 and H_ {2}S are common species of many fumaroles. If H2S is pumped through steel tubes Fe sulfides are forming and H2 is released. In the past several estimations of global volcanic metal fluxes to the atmosphere had been published. No attempt had been made to mine volcanic gases for certain elements. Filter experiments performed at a fumarole at La Fossa volcano, Vulcano Island, Italy and subsequent FESEM/EDS analysis document some phenomena difficult to explain. 1. On an Al-P-O ceramic filter applied for 5 mins. at a filter-2-bubblers system (0.8 - 1 l/min) once Hg-S-rich particles got collected, at another time Ce-La-carbonate particles. Other filters (borosilicate glass fiber and/or Nuclepore or Millipore (0.2 micrometers) applied for 1 h before or after the ceramic filters did not collect these particles. It remains unanswered if problems related to adhesion caused these results, or the ceramic filter had been in place at times of particle ``bursts", or classical physics cannot explain such phenomena. 2. Particles are nucleating on glass and organic fibers. One set of experiments followed a traditional aerosol particle collection approach utilizing a filter-2-bubblers system (AC). Another experiment had been the clogging of a fumarole vent by various glass fiber materials (CE). FESEM/EDS data from AC and CE show both nucleating particles on fibers. One data set of the AC and CE documents that one type of particle (CE: mostly metal chlorides, to a minor amount metal sulfides and AC: barberiite) nucleates on one fiber, whereas other fibers are empty. This single fiber anomaly had been detected up-to-now in the T range of 25 - ca. 300°C and at Bi-Cl. Bi chlorides are not known in nature. BiCl3 melts at 230-232°C, BiCl4 melts at 226°C. The T of the environment of nucleation had been ca. 300°C. Bismucolite (BiOCl) is a mineral, but can be excluded as an interpretation of the Bi-Cl data. A summary is given below according to elements important for H storage and detection on fibers by FESEM/EDS: Ti: Ti enrichment on organic coalescer at AC, Traces of Ti on GW at CE, Traces of Ti, [Cr or Mn(?)], Ni, Pb!, [Fe! - Cl, - S or Mo(?)] on GW at CE - fibers attached to corroded stainless steel (grade 316; no Ti, no Pb); N + B: Barberiite (?) NH_ {4}BF4 on GW at AC; Al: i.e. in cancrinite on GW at CE; Ni + Fe : Fe-Ni-(Cr)-Cl on RW & GW at CE; AN; Na: NaCl on various fibers at AC; K: KCl on various fibers at AC. Abbrevations: GW is a high-Si glass fiber; RW is a low-Si glass fiber; AN is Anodisc (Al-P-O); (!) = abundant; (or) = peak overlap in EDS. An approach to mine elements of fumarole gases needs intensified research on how filters work in such environments and which elements can pass the filters and might be collected in the bubbler systems. Such research could provide more information on volcanic systems. If such data also support economic arguments needs detailed quantification and hazard evaluation. References: Crabtree et al., 2004. Physics Today, 39-44, Dec. 2004. Fulignati et al., 2002. JVGR, 115, 397-410.

Municipal solid waste (MSW) source-classified collection represents an advancement in resource recycling and secondary pollution control in China. Comparative experiments were performed to assess the effect of a newly-established MSW source-classified collection system on polycyclic aromatic hydrocarbons (PAHs) in bottom ash from an incinerator (BA), fly ash from a boiler (FAB) and fly ash from a bag filter (FABF) of a full-scale MSW incinerator in China. Compared with FAB or FABF, PAHs were mainly concentrated in BA with a range of 1,961.0?2,420.2 ?g/kg. Total amounts of 16 high priority PAHs in BA, FAB and FABF from the classified MSW incineration were significantly reduced by 19.0%, 42.4% and 59.8% respectively in comparison with those from the traditional mixed MSW incineration. Moreov...

Continuous monitors can be used to supplement traditional filter-based methods of determining personal exposure to air pollutants. They have the advantages of being able to identify nearby sources and detect temporal changes on a time scale of a few minutes. The Windsor Ontario Exposure Assessment Study (WOEAS) adopted an approach of using multiple continuous monitors to measure indoor, outdoor (near-residential) and personal exposures to PM2.5, ultrafine particles and black carbon. About 48 adults and households were sampled for five consecutive 24-h periods in summer and winter 2005, and another 48 asthmatic children for five consecutive 24-h periods in summer and winter 2006. This article addresses the laboratory and field validation of these continuous monitors. A companion article (Wh...

We demonstrate an extremely simple and practical surface enhanced Raman spectroscopy (SERS) technique for trace chemical detection. Filter membranes first trap silver nanoparticles to form a SERS-active substrate and then concentrate analytes from a mL-scale sample into a ?L-scale detection volume. We demonstrate a significant improvement in detection limit as compared to colloidal SERS for the pesticide malathion and the food contaminant melamine. The measured SERS intensity exhibits low variation relative to traditional SERS techniques, and the data can be closely fit with a Langmuir isotherm. Thus, due to the simple procedure, the low-cost of the substrates, the quantitative results, and the performance improvement due to analyte concentration, our technique enables SERS to be practical for a broad range of analytical applications, including field-based detection of toxins in large-volume samples. PMID:22282766

Spatially variant apodization (SVA) is a nonlinear sidelobe reduction technique that improves sidelobe level and preserves resolution at the same time. This method implements a bidimensional finite impulse response filter with adaptive taps depending on image information. Some papers that have been previously published analyze SVA at the Nyquist rate or at higher rates focused on strip synthetic aperture radar (SAR). This paper shows that traditional SVA techniques are useless when the sensor operates with a squint angle. The reasons for this behaviour are analyzed, and a new implementation that largely improves the results is presented. The algorithm is applied to simulated SAR images in order to demonstrate the good quality achieved along with efficient computation. PMID:17688207

We formulate the problem of 3D human pose estimation and tracking as one of inference in a graphical model. Unlike traditional kinematic tree representations, our model of the body is a collection of loosely-connected body-parts. In particular, we model the body using an undirected graphical model in which nodes correspond to parts and edges to kinematic, penetration, and temporal constraints imposed by the joints and the world. These constraints are encoded using pair-wise statistical distributions, that are learned from motion-capture training data. Human pose and motion estimation is formulated as inference in this graphical model and is solved using Particle Message Passing (PaMPas). PaMPas is a form of non-parametric belief propagation that uses a variation of particle filtering that ...

While multiple species of inorganic arsenic can coexist in industrial environments, traditional air sampling methods and analysis by atomic absorption spectrometry quantify only total inorganic arsenic. The National Institute for Occupational Safety and Health (NIOSH) recently conducted laboratory experiments and field studies to develop a technique to separate mixtures of particulate inorganic arsenic compounds and arsine, and to detect and quantify arsenic trioxide vapor. A field study in a lead-acid battery manufacturing plant showed airborne particulate arsenic in Post Burn, Element Battery Repair, and Salvage and Remelt operations; measured widespread low levels of arsine; and suggested that both particulate arsenic and arsine were transported between work areas by in-plant air currents. Arsenic trioxide vapor contributed to the total airborne arsenic collected and was most prevalent in torching or welding areas. This finding suggests that, it the presence of heated arsenic sources, monitoring solely with conventional filters will underestimate arsenic exposure, because arsenic trioxide vapor is not efficiently collected.

Abstract in english This paper investigated the influence of organic loading on BOD and COD removal in primary facultative ponds. The study was based on six full-scale pond plants in which average removals of unfiltered biochemical oxygen demand (BOD) and chemical oxygen demand (COD) were 72 and 50%, respectively. For filtered samples, the removals were 89 and 83%, respectively. First-order removal rates assuming ideal hydraulic patterns (completely mixed and plug-flow) decreased with increm (more) ents in the mean hydraulic retention time (HRT). Reduction in organic loading also caused a decrease in removal rates. The results emphasized that HRT and surface organic loading are more reliable to estimate first-order removal rates than traditional Arrhenius-style equations. Thus, HRT and surface organic loading can be used to compute more realistic first-order removal rates and surface removal rates. An alternative design procedure based on HRT and surface organic loading was proposed and demonstrated.

The LHC will collide proton beams at a bunch-crossing rate of 40 MHz. At the design luminosity of $10^{34}$ cm$^{-2}$s$^{-1}$ each crossing results in an average of about 20 inelastic pp events. The CMS trigger system is designed to reduce the input rate to about 100 Hz. This task is carried out in two steps, namely the Level-1 (L1) and the High-Level trigger (HLT). The L1 trigger is built of customized fast electronics and is designed to reduce the rate to 100 kHz. The HLT is implemented in a filter farm running on hundreds of CPUs and is designed to reduce the rate by another factor of ~1000. It combines the traditional L2 and L3 trigger components in a novel way and allows the coherent tuning of the HLT algorithms to accommodate multiple physics channels. We will discuss the strategies for optimizing triggers covering the experiment`s early physics program.

A compact color schlieren system designed for field measurement of materials processing parameters has been built and tested in a microgravity environment. Improvements in the color filter design and a compact optical arrangement allowed the system described here to retain the traditional advantages of schlieren, such as simplicity, sensitivity, and ease of data interpretation. Testing was accomplished by successfully flying the instrument on a series of parabolic trajectories on the NASA KC-135 microgravity simulation aircraft. A variety of samples of interest in materials processing were examined. Although the present system was designed for aircraft use, the technique is well suited to space flight experimentation. A major goal of this effort was to accommodate the main optical system within a volume approximately equal to that of a Space Shuttle middeck locker. Future plans include the development of an automated space-qualified facility for use on the Shuttle and Space Station.

The black carbon (BC) component of ambient particulate matter is an important marker for combustion sources and for its impact on human health and radiative forcing. Extensive data archives exist for the black smoke metric, the historic measure of ambient particle darkness. An expression presented in earlier publications (Quincey, 2007; Quincey et al., 2011) for estimating BC concentrations from traditional black smoke measurements is shown to have limitations that can be addressed by using a more systematic approach to the issue of corrections for increasing darkening of the filter. The form of the more general relationship is shown to be an off-axis parabola rather than the on-axis parabola of the earlier work. Existing data from co-located black smoke and aethalometer measurements at 5 ...

In the traditional strapdown inertial navigation system/global positioning system (SINS/GPS) ultra-tight integration structure, the mutual aiding between SINS and GPS forms a positive feedback loop, through which measurement errors of both subsystems are coupled deeply. In signal jamming or/and dynamic conditions, the Doppler aiding error derived from the SINS using low-grade inertial measurement unit (IMU) can increase rapidly, and cause GPS measurement errors to be correlated with the SINS velocity errors. Such correlations can result in poor estimation accuracy of the integration Kalman filter, losing lock of tracking loops or even yielding system instability. To solve this problem, we propose to model tracking errors of the SINS aided phase lock loop and to derive a new tracking-error ...

We present a digital holography microscopy technique based on a parallel-quadrature phase-shifting method. Two ?/2 phase-shifted holograms are recorded simultaneously using polarization phase-shifting principle, slightly off-axis recording geometry, and two identical CCD sensors. The parallel phase-shifting is realized by combining circularly polarized object beam with a 45° degree polarized reference beam through a polarizing beam splitter. DC term is eliminated by subtracting the two holograms from each other and the object information is reconstructed after selecting the frequency spectrum of the real image. Both amplitude and phase object reconstruction results are presented. Simultaneous recording eliminates phase errors caused by mechanical vibrations and air turbulences. The slightly off-axis recording geometry with phase-shifting allows a much larger dimension of the spatial filter for reconstruction of the object information. This leads to better reconstruction capability than traditional off-axis holography.

Importance of document clustering is now widely acknowledged by researchers for better management, smart navigation, efficient filtering, and concise summarization of large collection of documents like World Wide Web (WWW). The next challenge lies in semantically performing clustering based on the semantic contents of the document. The problem of document clustering has two main components: (1) to represent the document in such a form that inherently captures semantics of the text. This may also help to reduce dimensionality of the document, and (2) to define a similarity measure based on the semantic representation such that it assigns higher numerical values to document pairs which have higher semantic relationship. Feature space of the documents can be very challenging for document clustering. A document may contain multiple topics, it may contain a large set of class-independent general-words, and a handful class-specific core-words. With these features in mind, traditional agglomerative clustering algori...

This paper presents the magnetic resonator piano, a hybrid acoustic-electronic instrument extending the traditional grand piano. Sound is produced without loudspeakers using electromagnetic actuators to directly manipulate the piano strings, expanding its vocabulary to include infinite sustain, notes that crescendo from silence, harmonics, and a variety of timbres. A feedback-based approach senses string vibrations from a single pickup on the soundboard, using filters and phase-locked loops to generate signals which reinforce the natural motion of each string. Signal-routing hardware enables coverage of all 88 notes of the piano using a standard digital audio interface. This paper describes the hardware, software, and performing interface of the instrument and presents measurements of ampl...

Lutein is concentrated in the primate retina, where together with zeaxanthin it forms the macular pigment. Traditionally lutein is characterized by its blue light filtering and anti-oxidant properties. Eliminating lutein from the diet of experimental animals results in early degenerative signs in the retina while patients with an acquired condition of macular pigment loss (Macular Telangiectasia) show serious visual handicap indicating the importance of macular pigment. Whether lutein intake reduces the risk of age related macular degeneration (AMD) or cataract formation is currently a strong matter of debate and abundant research is carried out to unravel the biological properties of the lutein molecule. SR-B1 has recently been identified as a lutein binding protein in the retina and this...

A filtration-aided acid cleaning method was used to collect biosilica structures from a diatom culture medium, natural seawater, or water bloom. Cell extraction, acid cleaning, and acid removal were all performed on a polytetrafluoroethylene (PTFE) filter cloth, significantly improving the treatment capacity and efficiency of the traditional acid wash method. Five typical diatoms were cultivated in the laboratory for acid cleaning. Different growth speeds were introduced, and different process parameters for acid cleaning were utilized. After the acid cleaning, biosilica structures were collected from the frustules of diatoms using different methods. Girdle bands and valves of Coscinodiscus sp. were separated by floating of the valves. Central spines of Ditylum brightwellii and valves of S...

In this article, we propose two schemes for sensor fault detection and accommodation (SFDA): one based on a neural network (NN) and the other on an extended Kalman filter (EKF). The objective of this article is to compare both approaches in terms of execution time, robustness to poorly modelled dynamics and sensitivity to different fault types. The schemes are tested on an unmanned air vehicle (UAV) application where traditional sensor redundancy methods can be too heavy and/or costly. In an attempt to reduce the false alarm rates and the number of undetected faults, a modified residual generator, originally proposed in Samy, Postlethwaite, and Gu in 2008 (Samy, I., Postlethwaite, I., and Gu, D.-W. (2008a). Neural Network Sensor Validation Scheme Demonstrated on a UAV Model, in IEEE Procee...

Pipelined Frequency Transform (PFT) is a new real-time conversion and filtering architecture that is said to be faster than Fast Fourier Transformation (FFT). When signals with large bandwidth (80 MHz and above) must be channelled in true-time, the power of the hardware and the effort laid down in the development of new software, and the work done on systems integration, all often increase exponentially with operational frequency and the number of channels to be processed. The challenge is no longer on the analogue side, but to handle the mass of digital data in true time. Pipelined Frequency Transform (PFT), which was developed and patented by RF Engines Ltd. in Great Britain, is a new type of hardware by means of which it is possible to achieve a much higher quality of real-time data at simpler hardware than with traditional use of FFT.

A multiphase LC voltage-controlled oscillator (VCO) with a novel capacitive coupling CL ladder filter structure is proposed in this paper and this 10 GHz eight-phase VCO is applied in clock and data recovery (CDR) circuit for 40 Gb/s optical communications system. Compared with the traditional eight-phase oscillator, this capacitive coupling structure can decrease the number of inductors to half and only of four inductors. The VCO is designed and taped out in TSMC 65 nm CMOS technology. Measurement results show the phase noise is 105.95 dBc/Hz at 1MHz offset from a carrier frequency of 10 GHz. The chip area of VCO is 480 ?m?700 ?m and the VCO core power dissipation is 4.8 mW with the 1.0 V supply voltage.

A polyacrylamide hydrogel containing the Chelex-100 resin has traditionally been used as the binding agent for the diffusion gradients in thin films (DGT) technique. The Chelex-100 resin, although important for the determination of various transition metals, is unsatisfactory for the determination of alkaline earth metals, particularly Ba. In this paper, a cellulose membrane, treated with phosphate (P81 membrane), was evaluated as a binding agent for DGT devices for the determination of Ba in produced formation water (PFW) samples. In addition, diffusive layers of filter paper (cellulose) were tested to diffuse Ba through the DGT devices. Experiments to evaluate the key variables of the technique (pH, deployment time, and ionic strength/salinity) were performed. The Ba sampled by these DGT...

A new method that can improve gas-chromatography-electroantennographic detection (GC-EAD) by orders of magnitude through a technique known as chopper stabilization combined with matched filtering in colored noise is presented. The EAD is a physiological recording from the antenna of an insect which can be used to find compounds in the GC effluent that the antenna is able to detect, having important applications for pest control and understanding of chemical communication in nature. The new method is demonstrated with whole-animal male Helicoverpa zea antennal preparations for detection of major pheromone component (cis-11-hexadecenal) and compared to results obtained using traditional EAD recording techniques. Results indicate that chopper stabilization under these circumstances can increa...

In this article we propose a novel face recognition method based on Principal Component Analysis (PCA) and Log-Gabor filters. The main advantages of the proposed method are its simple implementation, training, and very high recognition accuracy. For recognition experiments we used 5151 face images of 1311 persons from different sets of the FERET and AR databases that allow to analyze how recognition accuracy is affected by the change of facial expressions, illumination, and aging. Recognition experiments with the FERET database (containing photographs of 1196 persons) showed that our method can achieve maximal 97-98% first one recognition rate and 0.3-0.4% Equal Error Rate. The experiments also showed that the accuracy of our method is less affected by eye location errors and used image normalization method than of traditional PCA -based recognition method.

Abstract Micro-scale chromatography formats are becoming more routinely used in purification process development because of their ability to rapidly screen large number of process conditions at a time with minimal material. Given the usual constraints that exist on development timelines and resources, these systems can provide a means to maximize process knowledge and process robustness compared to traditional packed column formats. In this work, a high-throughput, 96-well filter plate format was used in the development of the cation exchange and hydrophobic interaction chromatography steps of a purification process designed to alter the glycoform distribution of a small protein. The significant input parameters affecting process performance were rapidly identified for both steps and preli...

The genotoxicity and toxicity of ethnomedicinal Philippine plants, which include Cassia fistula, Derris elliptica, Ficus elastica, Gliciridia sepium, Michelia alba, Morus alba, Pogostemon cablin and Ricinus communis, were tested using the Vitotox assay. The plants are used traditionally to treat several disorders like diabetes, weakness, menorrhagia, headache, toothache and rheumatism. The dried leaves were homogenized for overnight soaking in methanol at room temperature. The resulting alcoholic extracts were filtered and concentrated in vacuo and tested for their genotoxicity and cytotoxicity using Vitotox®. Results showed that the medicinal plants that were tested are not genotoxic nor cytotoxic, except for R. communis and P. cablin, which showed toxicity at high doses (low dilutions) in the absence of S9. PMID:20632380

ABSTRACT The Milliflex Rapid Microbiology Detection and Enumeration System (RMDS) is an automated platform developed for the rapid detection of microbial contaminants in filterable samples. Based on membrane filtration, adenosine triphosphate bioluminescence and image analysis, RMDS gives microorganism enumeration a detection time reduced by a factor of four compared to plate count. After sample filtration and incubation step, a universal lysis solution and bioluminescence reagent are automatically sprayed across the membrane. The membrane is then analyzed in a detection tower where light emission is captured by a charged coupled device camera. Data collected are treated, directly providing a result in colony-forming units. RMDS sensitivity is one cell and is equivalent to traditional micr...

Periploca sepium (PS) has traditionally been used in oriental medicine for treatment of rheumatoid arthritis (RA). We investigated the aqueous extract of PS (PSE) in its effects on human rheumatoid arthritis-derived fibroblast-like cells. In cell culture studies, PSE inhibited the growth and IL-6 production of the cells in dose dependent manners. The extract of Glycyrrhiza glabra (GG), which has also been used to treat RA and chosen as a reference here, slightly inhibited the growth of RA cells. A study of PSE fractionation indicated that the active material inhibiting IL-6 production is filterable by ultrafiltration, suggesting that substances with low molecular weight might be involved in an inhibition of IL-6 production. These results support the view that PSE represents a rich source of growth inhibition and anti-IL 6 production.   

In the tracking of a target using a radar or an imaging sensor, the acceleration of the target is usually modeled as a random vector (or the process noise in the state-space model) with known statistical properties. For a highly maneuvering target, the process noise has a large covariance matrix, and consequently, the estimated state has a large error. This paper proposes an approach that estimates the acceleration from the attitude of the target and uses the estimated acceleration for accurate tracking of the target. An imaging sensor is used for attitude estimation of the target (an aircraft; in this paper) as well as for tracking, without reliance on radar. Our simulation shows that the proposed method can track a maneuvering target much more accurately than traditional Kalman filters.   

Egypt has many unexplored archeological sites. The archeologists know where to search, but they like to know where to dig. Three shallow archeological sites of different soil types from Egypt (sand, mud and limestone) are investigated here using detailed geomagnetic measurements. Some traditional techniques and filters and other recent methods are applied on the total magnetic field to correlate the depths found from all methods. Euler deconvolution is constraint by the structural index of the source body, while the power spectrum is constraint by the spectral window of the FFT, scaling exponent and fitting method, and the other methods are constraint by the magnetic susceptibility contrast of the subsurface layers. The depth to the top of buried bodies and the horizontal location are calculated with high accuracy. Keywords: Magnetic Depth Estimation, Archeological sites, Euler deconvolution and power spectrum.

Traditional Intrusion Detection Systems (IDSs) are known for generating large volumes of alerts despite all the progress made over the last few years. The analysis of a huge number of raw alerts from large networks is often time consuming and labour intensive because the relevant alerts are usually buried under heaps of irrelevant alerts. Vulnerability based alert management approaches have received considerable attention and appear extremely promising in improving the quality of alerts. They filter out any alert that does not have a corresponding vulnerability hence enabling the analysts to focus on the important alerts. However, the existing vulnerability based approaches are still at the preliminary stage and there are some research gaps that need to be addressed. The act of validating ...

Abstract Efforts to address the chronic challenge of information overload in the digital world have focused on content filtering facilitated by information architecture (IA). Information professionals traditionally served as gatekeepers using formal information organization structures, systems and tools. The exploding quantity of contributed content on social media has magnified information overload and left content control and management largely up to users, who need to be educated in digital literacy (DLi) in order to assume this role. Thus, DLi's interface with IO is relatively clear. DLi also has a twofold role in the related field of IA. By default, information architects should be digitally literate themselves. Secondly, the users of information have to be aware of the importance of ...

The evolution of the job market has resulted in traditional methods of recruitment becoming insufficient. As it is now necessary to handle volumes of information (mostly in the form of free text) that are impossible to process manually, an analysis and assisted categorization are essential to address this issue. In this paper, we present a combination of the E-Gen and Cortex systems. E-Gen aims to perform analysis and categorization of job offers together with the responses given by the candidates. E-Gen system strategy is based on vectorial and probabilistic models to solve the problem of profiling applications according to a specific job offer. Cortex is a statistical automatic summarization system. In this work, E-Gen uses Cortex as a powerful filter to eliminate irrelevant information ...

Search engines, such as Google, assign scores to news articles based on their relevancy to a query. However, not all relevant articles for the query may be interesting to a user. For example, if the article is old or yields little new information, the article would be uninteresting. Relevancy scores do not take into account what makes an article interesting, which would vary from user to user. Although methods such as collaborative filtering have been shown to be effective in recommendation systems, in a limited user environment there are not enough users that would make collaborative filtering effective. I present a general framework for defining and measuring the ''interestingness'' of articles, called iScore, incorporating user-feedback including tracking multiple topics of interest as well as finding interesting entities or phrases in a complex relationship network. I propose and have shown the validity of the following: 1. Filtering based on only topic relevancy is insufficient for identifying interesting articles. 2. No single feature can characterize the interestingness of an article for a user. It is the combination of multiple features that yields higher quality results. For each user, these features have different degrees of usefulness for predicting interestingness. 3. Through user-feedback, a classifier can combine features to predict interestingness for the user. 4. Current evaluation corpora, such as TREC, do not capture all aspects of personalized news filtering systems necessary for system evaluation. 5. Focusing on only specific evolving user interests instead of all topics allows for more efficient resource utilization while yielding high quality recommendation results. 6. Multiple profile vectors yield significantly better results than traditional methods, such as the Rocchio algorithm, for identifying interesting articles. Additionally, the addition of tracking multiple topics as a new feature in iScore, can improve iScore's classification performance. 7. Multiple topic tracking yields better results than the best results from the last TREC adaptive filtering run. As future work, I will address the following hypothesis: Entities and the relationship among these entities using current information extraction technology can be utilized to identify entities of interest and relationships of interest, using a scheme such as PageRank. And I will address one of the following two hypotheses: 1. By addressing the multiple reading roles that a single user may have, classification results can be improved. 2. By tailoring the operating parameters of MTT, better classification results can be achieved.

A multistep inverse solution for two-dimensional electric field distribution is developed to deal with the nonlinear inverse problem of electric field distribution in relation to its boundary condition and the problem of divergence due to errors introduced by the ill-conditioned sensitivity matrix and the noise produced by electrode modelling and instruments. This solution is based on a normalized linear approximation method where the change in mutual impedance is derived from the sensitivity theorem and a method of error vector decomposition. This paper presents an algebraic solution of the linear equations at each inverse step, using a generalized conjugate gradients method. Limiting the number of iterations in the generalized conjugate gradients method controls the artificial errors introduced by the assumption of linearity and the ill-conditioned sensitivity matrix. The solution of the nonlinear problem is approached using a multistep inversion. This paper also reviews the mathematical and physical definitions of the sensitivity back-projection algorithm based on the sensitivity theorem. Simulations and discussion based on the multistep algorithm, the sensitivity coefficient back-projection method and the Newton-Raphson method are given. Examples of imaging gas-liquid mixing and a human hand in brine are presented.

We have developed and used a laser optoacoustic imaging system with transrectal probe (LOIS-P) for detection of mechanical lesions in canine prostates in vivo. LOIS images have been acquired with a 128-channel transrectal probe and a 32-channel data acquisition system. Optoacoustic images showed a strong contrast enhancement for a blood containing lesion, when compared with ultrasound images. Our studies demonstrated that sufficient optoacoustic contrast exists between blood containing lesion and prostate tissue, although the lesion has been undetectable with ultrasound. The imaging results have been compared with visual examination of surgically excised prostates. Although axial resolution of the wide-band transducers employed in the transrectal probe provides good axial resolution of 0.5 mm, the convex arc geometry of the this array of transducers provides lateral resolution degrading with depth in tissue. A two step algorithm has been developed to improve the lateral resolution of deeply located objects. This algorithm employs optoacoustic image reconstruction based on radial back-projection to determine location and shape of the target object, then a procedure, we call Maximum Angular Amplitude Probability (MAAP), to determine true brightness of the object and simultaneously remove arc-shaped artifacts associated with radial back-projection. A laser optoacoustic imaging system (LOIS-P) with transrectal probe operating in backward detection mode empowered with the new image reconstruction algorithm seems promising as a modality for detection of prostate cancer and guiding prostate biopsy.

This study reports the results of a numerical investigation and an experimental study on a round nozzle virtual impactor (VI) operated in two different modes. The newly proposed sampler, the semivolatile aerosol dichotomous sampler (SADS), was studied to overcome some of the problems of existing personal sampling methods such as evaporative loss during filter sampling. The main difference between VIs and the SADS was the inverted flow ratio between the major flow and the minor flow. Sampling in the SADS settings gives a lower cutsize in both numerical simulations and experimental results. Whereas the 50% separation efficiency for a VI occurred in numerical simulations when the square root of Stokes number equaled 0.97, the 50% efficiency for the same sampler run in the SADS settings occurred when the square root of the Stokes number was 0.27. The back pressure on each flow direction was studied and greater pressure drop was observed through the vapor flow in SADS settings. Sampling using a SADS was more effective than traditional filter methods because of its smaller cutsize, instant separation of vapor from particles and reduced particle losses. PMID:19279161

This paper proposes a collaborative filtering method for massive datasets that is based on Bayesian networks. We first compare the prediction accuracy of four scoring-based learning Bayesian networks algorithms (AIC, MDL, UPSM, and BDeu) and two conditional-independence-based (CI-based) learning Bayesian networks algorithms (MWST, and Polytree-MWST) using actual massive datasets. The results show that (1) for large networks, the scoring-based algorithms have lower prediction accuracy than the CI-based algorithms and (2) when the scoring-based algorithms use a greedy search to learn a large network, algorithms which make a lot of arcs tend to have less prediction accuracy than those that make fewer arcs. Next, we propose a learning algorithm based on MWST for collaborative filtering of massive datasets. The proposed algorithm employs a traditional data mining technique, the “a priori” algorithm, to quickly calculate the amount of mutual information, which is needed in MWST, from massive datasets. We compare the original MWST algorithm and the proposed algorithm on actual data, and the comparison shows the effectiveness of the proposed algorithm.   

In many manufacturing environments such as the nuclear weapons complex, emphasis has shifted from the regular production and delivery of large orders to infrequent small orders. However, the challenge to maintain the same high quality and reliability standards while building much smaller lot sizes remains. To meet this challenge, specific areas need more attention, including fast and on-target process start-up, low volume statistical process control, process characterization with small experiments, and estimating reliability given few actual performance tests of the product. In this paper we address the issue of low volume statistical process control. We investigate an adaptive filtering approach to process monitoring with a relatively short time series of autocorrelated data. The emphasis is on estimation and minimization of mean squared error rather than the traditional hypothesis testing and run length analyses associated with process control charting. We develop an adaptive filtering technique that assumes initial process parameters are unknown, and updates the parameters as more data become available. Using simulation techniques, we study the data requirements (the length of a time series of autocorrelated data) necessary to adequately estimate process parameters. We show that far fewer data values are needed than is typically recommended for process control applications. We also demonstrate the techniques with a case study from the nuclear weapons manufacturing complex.

Bitmap indices have been widely used in scientific applications and commercial systems for processing complex,multi-dimensional queries where traditional tree-based indices would not work efficiently. A common approach for reducing the size of a bitmap index for high cardinality attributes is to group ranges of values of an attribute into bins and then build a bitmap for each bin rather than a bitmap for each value of the attribute. Binning reduces storage costs,however, results of queries based on bins often require additional filtering for discarding it false positives, i.e., records in the result that do not satisfy the query constraints. This additional filtering,also known as ''candidate checking,'' requires access to the base data on disk and involves significant I/O costs. This paper studies strategies for minimizing the I/O costs for ''candidate checking'' for multi-dimensional queries. This is done by determining the number of bins allocated for each dimension and then placing bin boundaries in optimal locations. Our algorithms use knowledge of data distribution and query workload. We derive several analytical results concerning optimal bin allocation for a probabilistic query model. Our experimental evaluation with real life data shows an average I/O cost improvement of at least a factor of 10 for multi-dimensional queries on datasets from two different applications. Our experiments also indicate that the speedup increases with the number of query dimensions.

1.1 This test method covers the determination of detachable particulate contaminant 5 m or larger, in and on the fabric of clean room garments. 1.2 This test method does not apply to nonporous fabrics such as Tyvek or Gortex. It only applies to fabrics that are porous such as cotton or polyester. 1.3 The values stated in SI units are to be regarded as the standard. The inch-pound values given in parentheses are for information only. 1.4 This test method provides not only the traditional optical microscopic analysis but also a size distribution and surface obscuration analysis for particles on a fine-textured membrane filter or in a tape lift sample. It utilizes transmitted illumination to render all particles darker than the background for gray level detection. Particles collected on opaque plates must be transferred to a suitable membrane filter. This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns, if any, associat...

Search engines, such as Google, assign scores to news articles based on their relevance to a query. However, not all relevant articles for the query may be interesting to a user. For example, if the article is old or yields little new information, the article would be uninteresting. Relevance scores do not take into account what makes an article interesting, which would vary from user to user. Although methods such as collaborative filtering have been shown to be effective in recommendation systems, in a limited user environment, there are not enough users that would make collaborative filtering effective. A general framework, called iScore, is presented for defining and measuring the ‘‘interestingness of articles, incorporating user-feedback. iScore addresses the various aspects of what makes an article interesting, such as topic relevance, uniqueness, freshness, source reputation, and writing style. It employs various methods, such as multiple topic tracking, online parameter selection, language models, clustering, sentiment analysis, and phrase extraction to measure these features. Due to varying reasons that users hold about why an article is interesting, an online feature selection method in na?¨ve Bayes is also used to improve recommendation results. iScore can outperform traditional IR techniques by as much as 50.7%. iScore and its components are evaluated in the news recommendation task using three datasets from Yahoo! News, actual users, and Digg.

In this paper, we present an original observational approach, which combines, for the first time, traditional speckle imaging with image post-processing to obtain in the optical domain diffraction-limited images with high contrast (1e-5) within 0.5 to 2 arcseconds around a bright star. The post-processing step is based on wavelet filtering an has analogy with edge enhancement and high-pass filtering. Our I-band on-sky results with the 2.5-m Nordic Telescope (NOT) and the lucky imaging instrument FASTCAM show that we are able to detect L-type brown dwarf companions around a solar-type star with a contrast DI~12 at 2" and with no use of any coronographic capability, which greatly simplifies the instrumental and hardware approach. This object has been detected from the ground in J and H bands so far only with AO-assisted 8-10 m class telescopes (Gemini, Keck), although more recently detected with small-class telescopes in the K band. Discussing the advantage and disadvantage of the optical regime for the detecti...

In the last 10 years passive IR based (8--12 microns) motion sensing has matured to become the dominant method of volumetric space protection and surveillance. These systems currently cost less than $25 to produce and yet use traditionally expensive IR optics, filters, sensors and electronic circuitry. This IR application is quite interesting in that the volumes of systems produced and the costs and performance level required prove that there is potential for large scale commercial applications of IR technology. This paper will develop the basis and principles of operation of a staring motion sensor system using a technical approach. A model for the motion of the target is developed and compared to the background. The IR power difference between the target and the background as well as the optical requirements are determined from basic principles and used to determine the performance of the system. Low cost reflective and refractive IR optics and bandpass IR filters are discussed. The pyroelectric IR detector commonly used is fully discussed and characterized. Various schemes for ``false alarms`` have been developed and are also explained. This technology is also used in passive IR based motion sensors for other applications such as lighting control. These applications are also discussed. In addition the paper will discuss new developments in IR surveillance technology such as the use of linear motion sensing arrays. This presentation can be considered a ``primer`` on the art of Passive IR Motion Sensing as applied to Surveillance Technology.

HCl Treatment Followed By Bligh and Dyer Extraction Extract More Fatty Acids than Stoldt Fat Extraction in Feed and Fecal Samples., S.K. Jensen, C. Lauridsen, Aarhus University, Faculty of Agricultural Sciences, Tjele, Denmark. The official EU method for fatty acid analysis in feed is based on boiling of the feed sample in 3 M HCl followed by a filtration, drying, Soxhelet extraction of the fat with petrol ether, conversion of the fatty acids to their corresponding methyl esters and followed by GC separation. Besides being very time consuming, this method has several disadvantages, e.g. the filtration step may allow some shorter chain free fatty acids and some phospholipids to be washed through the filter and escape the analysis. Further, during the drying step of filter paper, oxidation of polyunsaturated fatty acids (PUFA) is a risk. Because of the mentioned disadvantages, a new method ("HCl-Bligh and Dyer method") has been developed, and compared with the traditional Stoldt fat extraction. The new method combines the HCl treatment of the sample with a Bligh and Dyer extraction (water-methanol-chloroform) of the lipid. Depending on the matrix (feed ?), the HCl-Bligh and Dyer extraction lead to 10-15% more total fatty acids and a 30-50% increase in some of the PUFA compared with the official EU method. Thus, besides being much more efficient for extraction of fatty acids, the HCl-Bligh and Dyer method is much faster, and allows inclusion of an internal standard from the beginning of the sample treatment.

Several modern optical coating designs tools are discussed in the frame of a new design paradigm proposing the search not for a formally optimal solution with the lowest possible merit function value but for the most practical solution that takes into account additional feasibility demands. Considered design tools include a stochastic optimization procedure that takes into account upper and lower constraints for layer optical thicknesses. This procedure allows one to obtain multiple solutions to a design problem, which presents additional opportunities for choosing a practically optimal design. Two special design techniques involving integer optimization also take into account additional demands. The first one is aimed at designing multicavity narrow bandpass filters with quarter wave or multiple quarter wave layer optical thicknesses. It enables obtaining bandpass filters with extremely steep transmittance slopes, bandwidths of several tens of nanometers, and very small ripples in transmission zones. The second technique is aimed at covering design problems that have been traditionally solved using the theory of equivalent layers. One more technique considered in this paper is aimed at reducing the influence of noncorrelated thickness errors on design spectral characteristics. PMID:23089788

Background There is evidence that household point-of-use (POU) water treatment products can reduce the enormous burden of water-borne illness. Nevertheless, adoption among the global poor is very low, and little evidence exists on why. Methods We gave 600 households in poor communities in Dhaka, Bangladesh randomly-ordered two-month free trials of four water treatment products: dilute liquid chlorine (sodium hypochlorite solution, marketed locally as Water Guard), sodium dichloroisocyanurate tablets (branded as Aquatabs), a combined flocculant-disinfectant powdered mixture (the PUR Purifier of Water), and a silver-coated ceramic siphon filter. Consumers also received education on the dangers of untreated drinking water. We measured which products consumers used with self-reports, observation (for the filter), and chlorine tests (for the other products). We also measured drinking water's contamination with E. coli (compared to 200 control households). Findings Households reported highest usage of the filter, although no product had even 30% usage. E. coli concentrations in stored drinking water were generally lowest when households had Water Guard. Households that self-reported product usage had large reductions in E. coli concentrations with any product as compared to controls. Conclusion Traditional arguments for the low adoption of POU products focus on affordability, consumers' lack of information about germs and the dangers of unsafe water, and specific products not meshing with a household's preferences. In this study we provided free trials, repeated informational messages explaining the dangers of untreated water, and a variety of product designs. The low usage of all products despite such efforts makes clear that important barriers exist beyond cost, information, and variation among these four product designs. Without a better understanding of the choices and aspirations of the target end-users, household-based water treatment is unlikely to reduce morbidity and mortality substantially in urban Bangladesh and similar populations. PMID:8086574