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1

Steps: A Grid Search Methodology for Optimized Peptide Identification Filtering of MS/MS Database Search Results  

PubMed Central

For bottom-up proteomics there are a wide variety of database searching algorithms in use for matching peptide sequences to tandem MS spectra. Likewise, there are numerous strategies being employed to produce a confident list of peptide identifications from the different search algorithm outputs. Here we introduce a grid search approach for determining optimal database filtering criteria in shotgun proteomics data analyses that is easily adaptable to any search. Systematic Trial and Error Parameter Selection – referred to as STEPS – utilizes user-defined parameter ranges to test a wide array of parameter combinations to arrive at an optimal “parameter set” for data filtering, thus maximizing confident identifications. The benefits of this approach in terms of numbers of true positive identifications are demonstrated using datasets derived from immunoaffinity-depleted blood serum and a bacterial cell lysate, two common proteomics sample types. PMID:23303698

Piehowski, Paul D.; Petyuk, Vladislav A.; Sandoval, John D.; Burnum, Kristin E.; Kiebel, Gary R.; Monroe, Matthew E.; Anderson, Gordon A.; Camp, David G.; Smith, Richard D.

2013-01-01

2

STEPS: A Grid Search Methodology for Optimized Peptide Identification Filtering of MS/MS Database Search Results  

SciTech Connect

For bottom-up proteomics there are a wide variety of database searching algorithms in use for matching peptide sequences to tandem MS spectra. Likewise, there are numerous strategies being employed to produce a confident list of peptide identifications from the different search algorithm outputs. Here we introduce a grid search approach for determining optimal database filtering criteria in shotgun proteomics data analyses that is easily adaptable to any search. Systematic Trial and Error Parameter Selection - referred to as STEPS - utilizes user-defined parameter ranges to test a wide array of parameter combinations to arrive at an optimal "parameter set" for data filtering, thus maximizing confident identifications. The benefits of this approach in terms of numbers of true positive identifications are demonstrated using datasets derived from immunoaffinity-depleted blood serum and a bacterial cell lysate, two common proteomics sample types.

Piehowski, Paul D.; Petyuk, Vladislav A.; Sandoval, John D.; Burnum, Kristin E.; Kiebel, Gary R.; Monroe, Matthew E.; Anderson, Gordon A.; Camp, David G.; Smith, Richard D.

2013-03-01

3

Optimal filtering and filter stability of linear stochastic delay systems  

NASA Technical Reports Server (NTRS)

Optimal filtering equations are obtained for very general linear stochastic delay systems. Stability of the optimal filter is studied in the case where there are no delays in the observations. Using the duality between linear filtering and control, asymptotic stability of the optimal filter is proved. Finally, the cascade of the optimal filter and the deterministic optimal quadratic control system is shown to be asymptotically stable as well.

Kwong, R. H.-S.; Willsky, A. S.

1977-01-01

4

OPTIMIZATION OF ADVANCED FILTER SYSTEMS  

SciTech Connect

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

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

1998-04-30

5

Compact elliptic-function low-pass filters using microstrip stepped-impedance hairpin resonators  

Microsoft Academic Search

A compact elliptic-function low-pass filter using microstrip stepped-impendance hairpin resonators and their equivalent-circuit models are developed. The prototype filters are synthesized from the equivalent-circuit model using available element-value tables. To optimize the performance of the filters, electromagnetic simulation is used to tune the dimensions of the prototype filters. The filter using multiple cascaded hairpin resonators provides a very sharp cutoff

Lung-Hwa Hsieh; Kai Chang

2003-01-01

6

Optimal PHD filter for single-target detection and tracking  

NASA Astrophysics Data System (ADS)

The PHD filter has attracted much international interest since its introduction in 2000. It is based on two approximations. First, it is a first-order approximation of the multitarget Bayes filter. Second, to achieve closed-form formulas for the Bayes data-update step, the predicted multitarget probability distribution must be assumed Poisson. In this paper we show how to derive an optimal PHD (OPHD) filter, given that target number does not exceed one. (That is, we restrict ourselves to the single-target detection and tracking problem.) We further show that, assuming no more than a single target, the following are identical: (1) the multitarget Bayes filter; (2) the OPHD filter; (3) the CPHD filter; and (4) the multi-hypothesis correlation (MHC) filter. We also note that all of these are generalizations of the probabilistic data association (IPDA) filter of Musicki, Evans, and Stankovic.

Maher, Ronald

2007-09-01

7

OPTIMIZATION OF ADVANCED FILTER SYSTEMS  

Microsoft Academic Search

Two advanced, hot gas, barrier filter system concepts have been proposed by the Siemens Westinghouse Power Corporation to improve the reliability and availability of barrier filter systems in applications such as PFBC and IGCC power generation. The two hot gas, barrier filter system concepts, the inverted candle filter system and the sheet filter system, were the focus of bench-scale testing,

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

2002-01-01

8

Labyrinth stepped seal geometric optimization  

E-print Network

. . . . . . . . . . . . . . . . 35 Influence of distance-to-contact on seal loss coefficient 38 Influence of radial step size on seal loss coefficient for smaller distance-to-contact and pitch values . . . . . . . . . . . . . . . . . . . 13 Influence of radial step size on seal... loss coefficient for larger distance-to-contact and pitch values . . . . . . . . . . . . . . . . . . . . . 41 14 Influence of radius size on seal loss coefficient for constant pitch 43 15 Influence of radius size on seal loss coefficient for small...

Wernig, Marcus Daniel

2012-06-07

9

OPTIMIZATION OF ADVANCED FILTER SYSTEMS  

SciTech Connect

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

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

2002-06-30

10

Broadband and Compact Coupled Coplanar Stripline Filters With Impedance Steps  

Microsoft Academic Search

Novel broadband and compact stepped-impedance coupled coplanar stripline bandpass filters are presented, analyzed theoretically, and demonstrated experimentally. These filters are based on impedance step, capacitive gap, broadside coupling, and inductive shorted strip discontinuities, which are modeled in terms of impedance (K-) and admittance (J-) inverters. Broadside coupled coplanar stripline is analyzed for the first time by the even-\\/odd-mode decomposition technique

Ning Yang; Christophe Caloz; Ke Wu; Zhi Ning Chen

2007-01-01

11

Multi-Object Optimal Design of Analog Filter Based on Improved Genetic Algorithm  

Microsoft Academic Search

A multi-object optimization method for analog filter design based on genetic algorithm (GA) is proposed. The complete objective function is a weighted sum of deviations between the properties of designed filter and these of desired filter, including the magnitude, phase responses and step response, etc. The optimization is achieved by GA to minimize the complete objective. For overcoming the disadvantages

Xie Qinlan; Chen Hong

2009-01-01

12

OPTIMIZATION OF ADVANCED FILTER SYSTEMS  

Microsoft Academic Search

Reliable, maintainable and cost effective hot gas particulate filter technology is critical to the successful commercialization of advanced, coal-fired power generation technologies, such as IGCC and PFBC. In pilot plant testing, the operating reliability of hot gas particulate filters have been periodically compromised by process issues, such as process upsets and difficult ash cake behavior (ash bridging and sintering), and

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

1998-01-01

13

Design of HTS transmit filter using step impedance resonators  

NASA Astrophysics Data System (ADS)

We have designed a high-temperature superconducting (HTS) transmit filter with step impedance resonators (SIRs). A transmit filter using half-wavelength straight-line resonators requires substantial spacing between adjacent resonators. This means that the filter needs a large substrate and that the number of poles is limited. Using SIRs overcomes this problem because SIRs are compact and have weak coupling. An electromagnetic simulator based on the moment method was used to design the SIR filter, which has a center frequency of 5 GHz and a bandwidth of 120 MHz. Simulation showed that it is approximately 19% smaller than a conventional half-wavelength straight-line resonator filter. Additionally, the maximum surface current is approximately 17% less than that of the conventional filter.

Sekiya, N.; Nakagawa, Y.; Ohshima, S.

2010-11-01

14

Steps Toward Optimal Competitive Scheduling  

NASA Technical Reports Server (NTRS)

This paper is concerned with the problem of allocating a unit capacity resource to multiple users within a pre-defined time period. The resource is indivisible, so that at most one user can use it at each time instance. However, different users may use it at different times. The users have independent, se@sh preferences for when and for how long they are allocated this resource. Thus, they value different resource access durations differently, and they value different time slots differently. We seek an optimal allocation schedule for this resource. This problem arises in many institutional settings where, e.g., different departments, agencies, or personal, compete for a single resource. We are particularly motivated by the problem of scheduling NASA's Deep Space Satellite Network (DSN) among different users within NASA. Access to DSN is needed for transmitting data from various space missions to Earth. Each mission has different needs for DSN time, depending on satellite and planetary orbits. Typically, the DSN is over-subscribed, in that not all missions will be allocated as much time as they want. This leads to various inefficiencies - missions spend much time and resource lobbying for their time, often exaggerating their needs. NASA, on the other hand, would like to make optimal use of this resource, ensuring that the good for NASA is maximized. This raises the thorny problem of how to measure the utility to NASA of each allocation. In the typical case, it is difficult for the central agency, NASA in our case, to assess the value of each interval to each user - this is really only known to the users who understand their needs. Thus, our problem is more precisely formulated as follows: find an allocation schedule for the resource that maximizes the sum of users preferences, when the preference values are private information of the users. We bypass this problem by making the assumptions that one can assign money to customers. This assumption is reasonable; a committee is usually in charge of deciding the priority of each mission competing for access to the DSN within a time period while scheduling. Instead, we can assume that the committee assigns a budget to each mission.This paper is concerned with the problem of allocating a unit capacity resource to multiple users within a pre-defined time period. The resource is indivisible, so that at most one user can use it at each time instance. However, different users may use it at different times. The users have independent, se@sh preferences for when and for how long they are allocated this resource. Thus, they value different resource access durations differently, and they value different time slots differently. We seek an optimal allocation schedule for this resource. This problem arises in many institutional settings where, e.g., different departments, agencies, or personal, compete for a single resource. We are particularly motivated by the problem of scheduling NASA's Deep Space Satellite Network (DSN) among different users within NASA. Access to DSN is needed for transmitting data from various space missions to Earth. Each mission has different needs for DSN time, depending on satellite and planetary orbits. Typically, the DSN is over-subscribed, in that not all missions will be allocated as much time as they want. This leads to various inefficiencies - missions spend much time and resource lobbying for their time, often exaggerating their needs. NASA, on the other hand, would like to make optimal use of this resource, ensuring that the good for NASA is maximized. This raises the thorny problem of how to measure the utility to NASA of each allocation. In the typical case, it is difficult for the central agency, NASA in our case, to assess the value of each interval to each user - this is really only known to the users who understand their needs. Thus, our problem is more precisely formulated as follows: find an allocation schedule for the resource that maximizes the sum ofsers preferences, when the preference values are private information of the users. We bypass this

Frank, Jeremy; Crawford, James; Khatib, Lina; Brafman, Ronen

2006-01-01

15

Two-step local Wiener filter using dual-tree complex wavelet transform  

NASA Astrophysics Data System (ADS)

Amongst various image denoising methods, the Wiener filter is known to be a mean-square optimal linear estimator for the true underlying image. The idea behind the Wiener filter frequently emerged in other image denoising algorithms. In this paper, we present a new denoising scheme for the Wiener filter. The algorithm is carried out by two subsequent steps. The output for the first step is used as the input for the second step. The ratio between the two step denoising amounts plays an important role for good performance. The relationship between the proposed method and the heat diffusion equation is established. The experiments show the proposed method outforms some of the denoising algorithm published currently.

Zhang, Xiao-bo; Feng, Xiang-chu

2011-08-01

16

A Variable Step-Size Matrix Normalized Subband Adaptive Filter  

Microsoft Academic Search

The normalized subband adaptive filter (NSAF) presented by Lee and Gan can obtain faster convergence rate than the normalized least-mean-square (NLMS) algorithm with colored input signals. However, similar to other fixed step-size adaptive filtering algorithms, the NSAF requires a tradeoff between fast convergence rate and low misadjustment. Recently, a set-membership NSAF (SM-NSAF) has been developed to address this problem. Nevertheless,

Jingen Ni; Feng Li

2010-01-01

17

Dual Adaptive Filtering by Optimal Projection Applied to Filter Muscle Artifacts on EEG and Comparative Study  

PubMed Central

Muscle artifacts constitute one of the major problems in electroencephalogram (EEG) examinations, particularly for the diagnosis of epilepsy, where pathological rhythms occur within the same frequency bands as those of artifacts. This paper proposes to use the method dual adaptive filtering by optimal projection (DAFOP) to automatically remove artifacts while preserving true cerebral signals. DAFOP is a two-step method. The first step consists in applying the common spatial pattern (CSP) method to two frequency windows to identify the slowest components which will be considered as cerebral sources. The two frequency windows are defined by optimizing convolutional filters. The second step consists in using a regression method to reconstruct the signal independently within various frequency windows. This method was evaluated by two neurologists on a selection of 114 pages with muscle artifacts, from 20 clinical recordings of awake and sleeping adults, subject to pathological signals and epileptic seizures. A blind comparison was then conducted with the canonical correlation analysis (CCA) method and conventional low-pass filtering at 30?Hz. The filtering rate was 84.3% for muscle artifacts with a 6.4% reduction of cerebral signals even for the fastest waves. DAFOP was found to be significantly more efficient than CCA and 30?Hz filters. The DAFOP method is fast and automatic and can be easily used in clinical EEG recordings. PMID:25298967

Peyrodie, Laurent; Szurhaj, William; Bolo, Nicolas; Pinti, Antonio; Gallois, Philippe

2014-01-01

18

Dual adaptive filtering by optimal projection applied to filter muscle artifacts on EEG and comparative study.  

PubMed

Muscle artifacts constitute one of the major problems in electroencephalogram (EEG) examinations, particularly for the diagnosis of epilepsy, where pathological rhythms occur within the same frequency bands as those of artifacts. This paper proposes to use the method dual adaptive filtering by optimal projection (DAFOP) to automatically remove artifacts while preserving true cerebral signals. DAFOP is a two-step method. The first step consists in applying the common spatial pattern (CSP) method to two frequency windows to identify the slowest components which will be considered as cerebral sources. The two frequency windows are defined by optimizing convolutional filters. The second step consists in using a regression method to reconstruct the signal independently within various frequency windows. This method was evaluated by two neurologists on a selection of 114 pages with muscle artifacts, from 20 clinical recordings of awake and sleeping adults, subject to pathological signals and epileptic seizures. A blind comparison was then conducted with the canonical correlation analysis (CCA) method and conventional low-pass filtering at 30 Hz. The filtering rate was 84.3% for muscle artifacts with a 6.4% reduction of cerebral signals even for the fastest waves. DAFOP was found to be significantly more efficient than CCA and 30 Hz filters. The DAFOP method is fast and automatic and can be easily used in clinical EEG recordings. PMID:25298967

Boudet, Samuel; Peyrodie, Laurent; Szurhaj, William; Bolo, Nicolas; Pinti, Antonio; Gallois, Philippe

2014-01-01

19

Spectral optimized asymmetric segmented phase-only correlation filter.  

PubMed

We suggest a new type of optimized composite filter, i.e., the asymmetric segmented phase-only filter (ASPOF), for improving the effectiveness of a VanderLugt correlator (VLC) when used for face identification. Basically, it consists in merging several reference images after application of a specific spectral optimization method. After segmentation of the spectral filter plane to several areas, each area is assigned to a single winner reference according to a new optimized criterion. The point of the paper is to show that this method offers a significant performance improvement on standard composite filters for face identification. We first briefly revisit composite filters [adapted, phase-only, inverse, compromise optimal, segmented, minimum average correlation energy, optimal trade-off maximum average correlation, and amplitude-modulated phase-only (AMPOF)], which are tools of choice for face recognition based on correlation techniques, and compare their performances with those of the ASPOF. We illustrate some of the drawbacks of current filters for several binary and grayscale image identifications. Next, we describe the optimization steps and introduce the ASPOF that can overcome these technical issues to improve the quality and the reliability of the correlation-based decision. We derive performance measures, i.e., PCE values and receiver operating characteristic curves, to confirm consistency of the results. We numerically find that this filter increases the recognition rate and decreases the false alarm rate. The results show that the discrimination of the ASPOF is comparable to that of the AMPOF, but the ASPOF is more robust than the trade-off maximum average correlation height against rotation and various types of noise sources. Our method has several features that make it amenable to experimental implementation using a VLC. PMID:22614484

Leonard, I; Alfalou, A; Brosseau, C

2012-05-10

20

Algorithmic and Architectural Optimizations for Computationally Efficient Particle Filtering  

E-print Network

filtering especially to video sequences. Particle filtering is a technique used for filtering non-linear, Auxillary variable, Design Methodologies, Visual Tracking I. INTRODUCTION Filtering is the problem scenarios. For example, Kalman filtering [1] is an optimal analytic filter when the models are linear

Chellappa, Rama

21

MEDOF - MINIMUM EUCLIDEAN DISTANCE OPTIMAL FILTER  

NASA Technical Reports Server (NTRS)

The Minimum Euclidean Distance Optimal Filter program, MEDOF, generates filters for use in optical correlators. The algorithm implemented in MEDOF follows theory put forth by Richard D. Juday of NASA/JSC. This program analytically optimizes filters on arbitrary spatial light modulators such as coupled, binary, full complex, and fractional 2pi phase. MEDOF optimizes these modulators on a number of metrics including: correlation peak intensity at the origin for the centered appearance of the reference image in the input plane, signal to noise ratio including the correlation detector noise as well as the colored additive input noise, peak to correlation energy defined as the fraction of the signal energy passed by the filter that shows up in the correlation spot, and the peak to total energy which is a generalization of PCE that adds the passed colored input noise to the input image's passed energy. The user of MEDOF supplies the functions that describe the following quantities: 1) the reference signal, 2) the realizable complex encodings of both the input and filter SLM, 3) the noise model, possibly colored, as it adds at the reference image and at the correlation detection plane, and 4) the metric to analyze, here taken to be one of the analytical ones like SNR (signal to noise ratio) or PCE (peak to correlation energy) rather than peak to secondary ratio. MEDOF calculates filters for arbitrary modulators and a wide range of metrics as described above. MEDOF examines the statistics of the encoded input image's noise (if SNR or PCE is selected) and the filter SLM's (Spatial Light Modulator) available values. These statistics are used as the basis of a range for searching for the magnitude and phase of k, a pragmatically based complex constant for computing the filter transmittance from the electric field. The filter is produced for the mesh points in those ranges and the value of the metric that results from these points is computed. When the search is concluded, the values of amplitude and phase for the k whose metric was largest, as well as consistency checks, are reported. A finer search can be done in the neighborhood of the optimal k if desired. The filter finally selected is written to disk in terms of drive values, not in terms of the filter's complex transmittance. Optionally, the impulse response of the filter may be created to permit users to examine the response for the features the algorithm deems important to the recognition process under the selected metric, limitations of the filter SLM, etc. MEDOF uses the filter SLM to its greatest potential, therefore filter competence is not compromised for simplicity of computation. MEDOF is written in C-language for Sun series computers running SunOS. With slight modifications, it has been implemented on DEC VAX series computers using the DEC-C v3.30 compiler, although the documentation does not currently support this platform. MEDOF can also be compiled using Borland International Inc.'s Turbo C++ v1.0, but IBM PC memory restrictions greatly reduce the maximum size of the reference images from which the filters can be calculated. MEDOF requires a two dimensional Fast Fourier Transform (2DFFT). One 2DFFT routine which has been used successfully with MEDOF is a routine found in "Numerical Recipes in C: The Art of Scientific Programming," which is available from Cambridge University Press, New Rochelle, NY 10801. The standard distribution medium for MEDOF is a .25 inch streaming magnetic tape cartridge (Sun QIC-24) in UNIX tar format. MEDOF was developed in 1992-1993.

Barton, R. S.

1994-01-01

22

OPTIMAL FILTERING TECHNIQUES FOR ANALYTICAL STREAMFLOW FORECASTING  

E-print Network

over the rocks, hard soil or ponds, lakes, and streams, produces direct runoff. Some water gets describes the development of a streamflow forecasting model based on the the Sacramento Soil Moisture Accounting Model and applies optimal filtering techniques to sequentially update watershed-scale soil

Simon, Dan

23

Optimal digital filtering for tremor suppression.  

PubMed

Remote manually operated tasks such as those found in teleoperation, virtual reality, or joystick-based computer access, require the generation of an intermediate electrical signal which is transmitted to the controlled subsystem (robot arm, virtual environment, or a cursor in a computer screen). When human movements are distorted, for instance, by tremor, performance can be improved by digitally filtering the intermediate signal before it reaches the controlled device. This paper introduces a novel tremor filtering framework in which digital equalizers are optimally designed through pursuit tracking task experiments. Due to inherent properties of the man-machine system, the design of tremor suppression equalizers presents two serious problems: 1) performance criteria leading to optimizations that minimize mean-squared error are not efficient for tremor elimination and 2) movement signals show ill-conditioned autocorrelation matrices, which often result in useless or unstable solutions. To address these problems, a new performance indicator in the context of tremor is introduced, and the optimal equalizer according to this new criterion is developed. Ill-conditioning of the autocorrelation matrix is overcome using a novel method which we call pulled-optimization. Experiments performed with artificially induced vibrations and a subject with Parkinson's disease show significant improvement in performance. Additional results, along with MATLAB source code of the algorithms, and a customizable demo for PC joysticks, are available on the Internet at http:¿tremor-suppression.com. PMID:10851810

Gonzalez, J G; Heredia, E A; Rahman, T; Barner, K E; Arce, G R

2000-05-01

24

FIR Filter Design via Spectral Factorization and Convex Optimization 1 FIR Filter Design via Spectral Factorization  

E-print Network

is optimization variable fi are convex: for 0 1, fix + 1 ,y fix + 1 ,fiy examples: linear & convex quadratic 1000s variables, 10000s constraints feasible on PC FIR Filter Design via Spectral FactorizationFIR Filter Design via Spectral Factorization and Convex Optimization 1 FIR Filter Design via

25

Metal finishing wastewater pressure filter optimization  

SciTech Connect

The 300-M Area Liquid Effluent Treatment Facility (LETF) of the Savannah River Site (SRS) is an end-of-pipe industrial wastewater treatment facility, that uses precipitation and filtration which is the EPA Best Available Technology economically achievable for a Metal Finishing and Aluminum Form Industries. The LETF consists of three close-coupled treatment facilities: the Dilute Effluent Treatment Facility (DETF), which uses wastewater equalization, physical/chemical precipitation, flocculation, and filtration; the Chemical Treatment Facility (CTF), which slurries the filter cake generated from the DETF and pumps it to interim-StatuS RCRA storage tanks; and the Interim Treatment/Storage Facility (IT/SF) which stores the waste from the CTF until the waste is stabilized/solidified for permanent disposal, 85% of the stored waste is from past nickel plating and aluminum canning of depleted uranium targets for the SRS nuclear reactors. Waste minimization and filtration efficiency are key to cost effective treatment of the supernate, because the waste filter cake generated is returned to the IT/SF. The DETF has been successfully optimized to achieve maximum efficiency and to minimize waste generation.

Norford, S.W.; Diener, G.A.; Martin, H.L.

1992-12-31

26

Metal finishing wastewater pressure filter optimization  

SciTech Connect

The 300-M Area Liquid Effluent Treatment Facility (LETF) of the Savannah River Site (SRS) is an end-of-pipe industrial wastewater treatment facility, that uses precipitation and filtration which is the EPA Best Available Technology economically achievable for a Metal Finishing and Aluminum Form Industries. The LETF consists of three close-coupled treatment facilities: the Dilute Effluent Treatment Facility (DETF), which uses wastewater equalization, physical/chemical precipitation, flocculation, and filtration; the Chemical Treatment Facility (CTF), which slurries the filter cake generated from the DETF and pumps it to interim-StatuS RCRA storage tanks; and the Interim Treatment/Storage Facility (IT/SF) which stores the waste from the CTF until the waste is stabilized/solidified for permanent disposal, 85% of the stored waste is from past nickel plating and aluminum canning of depleted uranium targets for the SRS nuclear reactors. Waste minimization and filtration efficiency are key to cost effective treatment of the supernate, because the waste filter cake generated is returned to the IT/SF. The DETF has been successfully optimized to achieve maximum efficiency and to minimize waste generation.

Norford, S.W.; Diener, G.A.; Martin, H.L.

1992-01-01

27

On Incremental Sigma-Delta Modulation with Optimal Filtering  

E-print Network

On Incremental Sigma-Delta Modulation with Optimal Filtering Sam Kavusi, Student Member, IEEE derivation of the Zoomer algorithm. Index Terms Sigma-Delta (), incremental A/D converter, optimal filter@isl.stanford.edu). #12;IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS­I: REGULAR PAPERS, 1 On Incremental Sigma-Delta

El Gamal, Abbas

28

A hybrid method for optimization of the adaptive Goldstein filter  

NASA Astrophysics Data System (ADS)

The Goldstein filter is a well-known filter for interferometric filtering in the frequency domain. The main parameter of this filter, alpha, is set as a power of the filtering function. Depending on it, considered areas are strongly or weakly filtered. Several variants have been developed to adaptively determine alpha using different indicators such as the coherence, and phase standard deviation. The common objective of these methods is to prevent areas with low noise from being over filtered while simultaneously allowing stronger filtering over areas with high noise. However, the estimators of these indicators are biased in the real world and the optimal model to accurately determine the functional relationship between the indicators and alpha is also not clear. As a result, the filter always under- or over-filters and is rarely correct. The study presented in this paper aims to achieve accurate alpha estimation by correcting the biased estimator using homogeneous pixel selection and bootstrapping algorithms, and by developing an optimal nonlinear model to determine alpha. In addition, an iteration is also merged into the filtering procedure to suppress the high noise over incoherent areas. The experimental results from synthetic and real data show that the new filter works well under a variety of conditions and offers better and more reliable performance when compared to existing approaches.

Jiang, Mi; Ding, Xiaoli; Tian, Xin; Malhotra, Rakesh; Kong, Weixue

2014-12-01

29

Optimal filtering versus regularization methods in the Fourier precompensation based proximity neurocorrection in Electron Beam Lithography  

Microsoft Academic Search

In this paper proximity effects correction in Electron Beam Lithography by means of an artificial neural network is presented. Supporting approximations to cope with negative doses inherent in Gibbs oscillations which occur from step-like function representation in the Fourier space are introduced. Miller regularization theory as better alternative to Tikhonov one is presented. Optimal filtering with prolate spheriodal wave functions

P. Jedrasik; J. Garcia; B. De Boeck; D Van Dyck

1998-01-01

30

Optimal filter bandwidth for pulse oximetry  

NASA Astrophysics Data System (ADS)

Pulse oximeters contain one or more signal filtering stages between the photodiode and microcontroller. These filters are responsible for removing the noise while retaining the useful frequency components of the signal, thus improving the signal-to-noise ratio. The corner frequencies of these filters affect not only the noise level, but also the shape of the pulse signal. Narrow filter bandwidth effectively suppresses the noise; however, at the same time, it distorts the useful signal components by decreasing the harmonic content. In this paper, we investigated the influence of the filter bandwidth on the accuracy of pulse oximeters. We used a pulse oximeter tester device to produce stable, repetitive pulse waves with digitally adjustable R ratio and heart rate. We built a pulse oximeter and attached it to the tester device. The pulse oximeter digitized the current of its photodiode directly, without any analog signal conditioning. We varied the corner frequency of the low-pass filter in the pulse oximeter in the range of 0.66-15 Hz by software. For the tester device, the R ratio was set to R = 1.00, and the R ratio deviation measured by the pulse oximeter was monitored as a function of the corner frequency of the low-pass filter. The results revealed that lowering the corner frequency of the low-pass filter did not decrease the accuracy of the oxygen level measurements. The lowest possible value of the corner frequency of the low-pass filter is the fundamental frequency of the pulse signal. We concluded that the harmonics of the pulse signal do not contribute to the accuracy of pulse oximetry. The results achieved by the pulse oximeter tester were verified by human experiments, performed on five healthy subjects. The results of the human measurements confirmed that filtering out the harmonics of the pulse signal does not degrade the accuracy of pulse oximetry.

Stuban, Norbert; Niwayama, Masatsugu

2012-10-01

31

Optimal filter bandwidth for pulse oximetry.  

PubMed

Pulse oximeters contain one or more signal filtering stages between the photodiode and microcontroller. These filters are responsible for removing the noise while retaining the useful frequency components of the signal, thus improving the signal-to-noise ratio. The corner frequencies of these filters affect not only the noise level, but also the shape of the pulse signal. Narrow filter bandwidth effectively suppresses the noise; however, at the same time, it distorts the useful signal components by decreasing the harmonic content. In this paper, we investigated the influence of the filter bandwidth on the accuracy of pulse oximeters. We used a pulse oximeter tester device to produce stable, repetitive pulse waves with digitally adjustable R ratio and heart rate. We built a pulse oximeter and attached it to the tester device. The pulse oximeter digitized the current of its photodiode directly, without any analog signal conditioning. We varied the corner frequency of the low-pass filter in the pulse oximeter in the range of 0.66-15 Hz by software. For the tester device, the R ratio was set to R = 1.00, and the R ratio deviation measured by the pulse oximeter was monitored as a function of the corner frequency of the low-pass filter. The results revealed that lowering the corner frequency of the low-pass filter did not decrease the accuracy of the oxygen level measurements. The lowest possible value of the corner frequency of the low-pass filter is the fundamental frequency of the pulse signal. We concluded that the harmonics of the pulse signal do not contribute to the accuracy of pulse oximetry. The results achieved by the pulse oximeter tester were verified by human experiments, performed on five healthy subjects. The results of the human measurements confirmed that filtering out the harmonics of the pulse signal does not degrade the accuracy of pulse oximetry. PMID:23126791

Stuban, Norbert; Niwayama, Masatsugu

2012-10-01

32

Initial steps of inactivation at the K+ channel selectivity filter  

PubMed Central

K+ efflux through K+ channels can be controlled by C-type inactivation, which is thought to arise from a conformational change near the channel’s selectivity filter. Inactivation is modulated by ion binding near the selectivity filter; however, the molecular forces that initiate inactivation remain unclear. We probe these driving forces by electrophysiology and molecular simulation of MthK, a prototypical K+ channel. Either Mg2+ or Ca2+ can reduce K+ efflux through MthK channels. However, Ca2+, but not Mg2+, can enhance entry to the inactivated state. Molecular simulations illustrate that, in the MthK pore, Ca2+ ions can partially dehydrate, enabling selective accessibility of Ca2+ to a site at the entry to the selectivity filter. Ca2+ binding at the site interacts with K+ ions in the selectivity filter, facilitating a conformational change within the filter and subsequent inactivation. These results support an ionic mechanism that precedes changes in channel conformation to initiate inactivation. PMID:24733889

Thomson, Andrew S.; Heer, Florian T.; Smith, Frank J.; Hendron, Eunan; Berneche, Simon; Rothberg, Brad S.

2014-01-01

33

Robustness of optimal binary filters: analysis and design  

E-print Network

and these are governed by parameterized probability laws. The optimal filter is found relative to these laws. Qualitatively, a filter is said to be robust when its performance degradation is acceptable for processes statistically close to the one for which it has been...

Grigoryan, Artyom M

2012-06-07

34

A Filter-Based Evolutionary Algorithm for Constrained Optimization  

Microsoft Academic Search

We introduce a filter-based evolutionary algorithm (FEA) for constrained optimization. The filter used by an FEA explicitly imposes the concept of dominance on a partially ordered solution set. We show that the algorithm is provably robust for both linear and nonlinear problems and constraints. FEAs use a finite pattern of mutation offsets, and our analysis is closely related to recent

Lauren M. Clevenger; Lauren Ferguson; William E. Hart

2005-01-01

35

Optimization of tunable silicon compatible microring filters  

E-print Network

Microring resonators can be used as pass-band filters for wavelength division demultiplexing in electronic-photonic integrated circuits for applications such as analog-to-digital converters (ADCs). For high quality signal ...

Amatya, Reja

2008-01-01

36

Optimal wavelet filter construction using X and Y data  

Microsoft Academic Search

It has been recently shown that the predictive ability of wavelet models in multivariate calibration problems can be improved by optimizing the filters employed in the Discrete Wavelet Transform (DWT) with respect to the statistics of the matrix of instrumental responses. However, no attempt has been made at exploiting the statistics of the matrix of predicted parameters in the optimization

Roberto Kawakami Harrop Galvão; Gledson Em??dio José; Heronides Adonias Dantas Filho; Mario Cesar Ugulino Araujo; Edvan Cirino da Silva; Henrique Mohallem Paiva; Teresa Cristina Bezerra Saldanha; Ênio Sartre Oliveira Nunes de Souza

2004-01-01

37

Optimal digital filtering for tremor suppression  

Microsoft Academic Search

Remote manually operated tasks such as those found in teleoperation, virtual reality, or joystick-based computer access, require the generation of an intermediate electrical signal which is transmitted to the controlled subsystem (robot arm, virtual environment, or a cursor in a computer screen). When human movements are distorted, for instance, by tremor, performance can be improved by digitally filtering the intermediate

Juan G. Gonzalez; Edwin A. Heredia; Tariq Rahman; Kenneth E. Barner; Gonzalo R. Arce

2000-01-01

38

New Complex-Step Derivative Approximations with Application to Second-Order Kalman Filtering  

E-print Network

New Complex-Step Derivative Approximations with Application to Second-Order Kalman Filtering Kok extensions of the complex-step approximation to compute numerical derivatives. For first derivatives achieve near analytical accuracy. However, for second derivatives straight implementation of the complex

Crassidis, John L.

39

Ares-I Bending Filter Design using a Constrained Optimization Approach  

NASA Technical Reports Server (NTRS)

The Ares-I launch vehicle represents a challenging flex-body structural environment for control system design. Software filtering of the inertial sensor output is required to ensure adequate stable response to guidance commands while minimizing trajectory deviations. This paper presents a design methodology employing numerical optimization to develop the Ares-I bending filters. The design objectives include attitude tracking accuracy and robust stability with respect to rigid body dynamics, propellant slosh, and flex. Under the assumption that the Ares-I time-varying dynamics and control system can be frozen over a short period of time, the bending filters are designed to stabilize all the selected frozen-time launch control systems in the presence of parameter uncertainty. To ensure adequate response to guidance command, step response specifications are introduced as constraints in the optimization problem. Imposing these constrains minimizes performance degradation caused by the addition of the bending filters. The first stage bending filter design achieves stability by adding lag to the first structural frequency to phase stabilize the first flex mode while gain stabilizing the higher modes. The upper stage bending filter design gain stabilizes all the flex bending modes. The bending filter designs provided here have been demonstrated to provide stable first and second stage control systems in both Draper Ares Stability Analysis Tool (ASAT) and the MSFC MAVERIC 6DOF nonlinear time domain simulation.

Hall, Charles; Jang, Jiann-Woei; Hall, Robert; Bedrossian, Nazareth

2008-01-01

40

Identifying Optimal Measurement Subspace for the Ensemble Kalman Filter  

SciTech Connect

To reduce the computational load of the ensemble Kalman filter while maintaining its efficacy, an optimization algorithm based on the generalized eigenvalue decomposition method is proposed for identifying the most informative measurement subspace. When the number of measurements is large, the proposed algorithm can be used to make an effective tradeoff between computational complexity and estimation accuracy. This algorithm also can be extended to other Kalman filters for measurement subspace selection.

Zhou, Ning; Huang, Zhenyu; Welch, Greg; Zhang, J.

2012-05-24

41

Design of optimal correlation filters for hybrid vision systems  

NASA Technical Reports Server (NTRS)

Research is underway at the NASA Johnson Space Center on the development of vision systems that recognize objects and estimate their position by processing their images. This is a crucial task in many space applications such as autonomous landing on Mars sites, satellite inspection and repair, and docking of space shuttle and space station. Currently available algorithms and hardware are too slow to be suitable for these tasks. Electronic digital hardware exhibits superior performance in computing and control; however, they take too much time to carry out important signal processing operations such as Fourier transformation of image data and calculation of correlation between two images. Fortunately, because of the inherent parallelism, optical devices can carry out these operations very fast, although they are not quite suitable for computation and control type operations. Hence, investigations are currently being conducted on the development of hybrid vision systems that utilize both optical techniques and digital processing jointly to carry out the object recognition tasks in real time. Algorithms for the design of optimal filters for use in hybrid vision systems were developed. Specifically, an algorithm was developed for the design of real-valued frequency plane correlation filters. Furthermore, research was also conducted on designing correlation filters optimal in the sense of providing maximum signal-to-nose ratio when noise is present in the detectors in the correlation plane. Algorithms were developed for the design of different types of optimal filters: complex filters, real-value filters, phase-only filters, ternary-valued filters, coupled filters. This report presents some of these algorithms in detail along with their derivations.

Rajan, Periasamy K.

1990-01-01

42

Improvements of Adaptive Filtering by Optimal Projection to filter different artifact types on long duration EEG recordings.  

PubMed

Adaptive Filtering by Optimal Projection (AFOP) is an automatic method for reducing ocular and muscular artifacts on electro-encephalographic (EEG) recordings. This paper presents two additions to this method: an improvement of the stability of ocular artifact filtering and an adaptation of the method for filtering electrode artifacts. With these improvements, it is possible to reduce almost all the current types of artifacts, while preserving brain signals, particularly those characterising epilepsy. This generalised method consists of dividing the signal into several time-frequency windows, and in applying different spatial filters to each. Two steps are required to define one of these spatial filters: the first step consists of defining artifact spatial projection using the Common Spatial Pattern (CSP) method and the second consists of defining EEG spatial projection via regression. For this second step, a progressive orthogonalisation process is proposed to improve stability. This method has been tested on long-duration EEG recordings of epileptic patients. A neurologist quantified the ratio of removed artifacts and the ratio of preserved EEG. Among the 330 artifacted pages used for evaluation, readability was judged better for 78% of pages, equal for 20% of pages, and worse for 2%. Artifact amplitudes were reduced by 80% on average. At the same time, brain sources were preserved in amplitude from 70% to 95% depending on the type of waves (alpha, theta, delta, spikes, etc.). A blind comparison with manual Independent Component Analysis (ICA) was also realised. The results show that this method is competitive and useful for routine clinical practice. PMID:22717094

Boudet, S; Peyrodie, L; Forzy, G; Pinti, A; Toumi, H; Gallois, P

2012-10-01

43

Optimal Filtering Methods to Structural Damage Estimation under Ground Excitation  

PubMed Central

This paper considers the problem of shear building damage estimation subject to earthquake ground excitation using the Kalman filtering approach. The structural damage is assumed to take the form of reduced elemental stiffness. Two damage estimation algorithms are proposed: one is the multiple model approach via the optimal two-stage Kalman estimator (OTSKE), and the other is the robust two-stage Kalman filter (RTSKF), an unbiased minimum-variance filtering approach to determine the locations and extents of the damage stiffness. A numerical example of a six-storey shear plane frame structure subject to base excitation is used to illustrate the usefulness of the proposed results. PMID:24453869

Hsieh, Chien-Shu; Liaw, Der-Cherng; Lin, Tzu-Hsuan

2013-01-01

44

Optimal Recursive Digital Filters for Active Bending Stabilization  

NASA Technical Reports Server (NTRS)

In the design of flight control systems for large flexible boosters, it is common practice to utilize active feedback control of the first lateral structural bending mode so as to suppress transients and reduce gust loading. Typically, active stabilization or phase stabilization is achieved by carefully shaping the loop transfer function in the frequency domain via the use of compensating filters combined with the frequency response characteristics of the nozzle/actuator system. In this paper we present a new approach for parameterizing and determining optimal low-order recursive linear digital filters so as to satisfy phase shaping constraints for bending and sloshing dynamics while simultaneously maximizing attenuation in other frequency bands of interest, e.g. near higher frequency parasitic structural modes. By parameterizing the filter directly in the z-plane with certain restrictions, the search space of candidate filter designs that satisfy the constraints is restricted to stable, minimum phase recursive low-pass filters with well-conditioned coefficients. Combined with optimal output feedback blending from multiple rate gyros, the present approach enables rapid and robust parametrization of autopilot bending filters to attain flight control performance objectives. Numerical results are presented that illustrate the application of the present technique to the development of rate gyro filters for an exploration-class multi-engined space launch vehicle.

Orr, Jeb S.

2013-01-01

45

Optimization of filtering schemes for broadband astro-combs.  

PubMed

To realize a broadband, large-line-spacing astro-comb, suitable for wavelength calibration of astrophysical spectrographs, from a narrowband, femtosecond laser frequency comb ("source-comb"), one must integrate the source-comb with three additional components: (1) one or more filter cavities to multiply the source-comb's repetition rate and thus line spacing; (2) power amplifiers to boost the power of pulses from the filtered comb; and (3) highly nonlinear optical fiber to spectrally broaden the filtered and amplified narrowband frequency comb. In this paper we analyze the interplay of Fabry-Perot (FP) filter cavities with power amplifiers and nonlinear broadening fiber in the design of astro-combs optimized for radial-velocity (RV) calibration accuracy. We present analytic and numeric models and use them to evaluate a variety of FP filtering schemes (labeled as identical, co-prime, fraction-prime, and conjugate cavities), coupled to chirped-pulse amplification (CPA). We find that even a small nonlinear phase can reduce suppression of filtered comb lines, and increase RV error for spectrograph calibration. In general, filtering with two cavities prior to the CPA fiber amplifier outperforms an amplifier placed between the two cavities. In particular, filtering with conjugate cavities is able to provide <1 cm/s RV calibration error with >300 nm wavelength coverage. Such superior performance will facilitate the search for and characterization of Earth-like exoplanets, which requires <10 cm/s RV calibration error. PMID:23187265

Chang, Guoqing; Li, Chih-Hao; Phillips, David F; Szentgyorgyi, Andrew; Walsworth, Ronald L; Kärtner, Franz X

2012-10-22

46

Optimal Filter Estimation for Lucas-Kanade Optical Flow  

PubMed Central

Optical flow algorithms offer a way to estimate motion from a sequence of images. The computation of optical flow plays a key-role in several computer vision applications, including motion detection and segmentation, frame interpolation, three-dimensional scene reconstruction, robot navigation and video compression. In the case of gradient based optical flow implementation, the pre-filtering step plays a vital role, not only for accurate computation of optical flow, but also for the improvement of performance. Generally, in optical flow computation, filtering is used at the initial level on original input images and afterwards, the images are resized. In this paper, we propose an image filtering approach as a pre-processing step for the Lucas-Kanade pyramidal optical flow algorithm. Based on a study of different types of filtering methods and applied on the Iterative Refined Lucas-Kanade, we have concluded on the best filtering practice. As the Gaussian smoothing filter was selected, an empirical approach for the Gaussian variance estimation was introduced. Tested on the Middlebury image sequences, a correlation between the image intensity value and the standard deviation value of the Gaussian function was established. Finally, we have found that our selection method offers a better performance for the Lucas-Kanade optical flow algorithm.

Sharmin, Nusrat; Brad, Remus

2012-01-01

47

Iterative gradient technique for the design of least squares optimal FIR magnitude squared Nyquist filters  

Microsoft Academic Search

Recently, much attention has been given to the design of optimal finite impulse response (FIR) compaction filters. Such filters, which arise in the design of optimal signal-adapted orthonormal FIR filter banks, satisfy a magnitude squared Nyquist constraint in addition to the inherent FIR assumption. In this paper, we focus on the least squares optimal design of FIR filters whose magnitude

Andre Tkacenko; P. P. Vaidyanathan

2004-01-01

48

Optimal Signal Processing of Frequency-Stepped CW Radar Data  

NASA Technical Reports Server (NTRS)

An optimal signal processing algorithm is derived for estimating the time delay and amplitude of each scatterer reflection using a frequency-stepped CW system. The channel is assumed to be composed of abrupt changes in the reflection coefficient profile. The optimization technique is intended to maximize the target range resolution achievable from any set of frequency-stepped CW radar measurements made in such an environment. The algorithm is composed of an iterative two-step procedure. First, the amplitudes of the echoes are optimized by solving an overdetermined least squares set of equations. Then, a nonlinear objective function is scanned in an organized fashion to find its global minimum. The result is a set of echo strengths and time delay estimates. Although this paper addresses the specific problem of resolving the time delay between the first two echoes, the derivation is general in the number of echoes. Performance of the optimization approach is illustrated using measured data obtained from an HP-X510 network analyzer. It is demonstrated that the optimization approach offers a significant resolution enhancement over the standard processing approach that employs an IFFT. Degradation in the performance of the algorithm due to suboptimal model order selection and the effects of additive white Gaussion noise are addressed.

Ybarra, Gary A.; Wu, Shawkang M.; Bilbro, Griff L.; Ardalan, Sasan H.; Hearn, Chase P.; Neece, Robert T.

1995-01-01

49

Optimal Signal Processing of Frequency-Stepped CW Radar Data  

NASA Technical Reports Server (NTRS)

An optimal signal processing algorithm is derived for estimating the time delay and amplitude of each scatterer reflection using a frequency-stepped CW system. The channel is assumed to be composed of abrupt changes in the reflection coefficient profile. The optimization technique is intended to maximize the target range resolution achievable from any set of frequency-stepped CW radar measurements made in such an environment. The algorithm is composed of an iterative two-step procedure. First, the amplitudes of the echoes are optimized by solving an overdetermined least squares set of equations. Then, a nonlinear objective function is scanned in an organized fashion to find its global minimum. The result is a set of echo strengths and time delay estimates. Although this paper addresses the specific problem of resolving the time delay between the two echoes, the derivation is general in the number of echoes. Performance of the optimization approach is illustrated using measured data obtained from an HP-851O network analyzer. It is demonstrated that the optimization approach offers a significant resolution enhancement over the standard processing approach that employs an IFFT. Degradation in the performance of the algorithm due to suboptimal model order selection and the effects of additive white Gaussion noise are addressed.

Ybarra, Gary A.; Wu, Shawkang M.; Bilbro, Griff L.; Ardalan, Sasan H.; Hearn, Chase P.; Neece, Robert T.

1995-01-01

50

Swarm Intelligence for Optimizing Hybridized Smoothing Filter in Image Edge Enhancement  

NASA Astrophysics Data System (ADS)

In this modern era, image transmission and processing plays a major role. It would be impossible to retrieve information from satellite and medical images without the help of image processing techniques. Edge enhancement is an image processing step that enhances the edge contrast of an image or video in an attempt to improve its acutance. Edges are the representations of the discontinuities of image intensity functions. For processing these discontinuities in an image, a good edge enhancement technique is essential. The proposed work uses a new idea for edge enhancement using hybridized smoothening filters and we introduce a promising technique of obtaining best hybrid filter using swarm algorithms (Artificial Bee Colony (ABC), Particle Swarm Optimization (PSO) and Ant Colony Optimization (ACO)) to search for an optimal sequence of filters from among a set of rather simple, representative image processing filters. This paper deals with the analysis of the swarm intelligence techniques through the combination of hybrid filters generated by these algorithms for image edge enhancement.

Rao, B. Tirumala; Dehuri, S.; Dileep, M.; Vindhya, A.

51

Optimal Design of --() Filters Dirk Tenne Tarunraj Singh,  

E-print Network

. An optimal selection of , and parameters is provided for various penalties on the noise filtering. 1 select the set of the smoothing parameters which minimize the noise transmission ca- pability to #12;lie within the unit circle to guarantee stability. Jury's Stability Test [5] yields

Singh, Tarunraj

52

An automated framework for multicriteria optimization of analog filter designs  

Microsoft Academic Search

This paper presents an extensible framework for designing analog filters that exhibit several desired behavioral properties after being realized in circuits. In the framework, we model the constrained nonlinear optimization problem as a sequential quadratic programming (SQP) problem. SQP requires real-valued constraints and objective functions that are differentiable with respect to the free parameters (pole-zero locations). We derive the differentiable

Niranjan Damera-Venkata; Brian L. Evans

1999-01-01

53

Na-Faraday rotation filtering: The optimal point.  

PubMed

Narrow-band optical filtering is required in many spectroscopy applications to suppress unwanted background light. One example is quantum communication where the fidelity is often limited by the performance of the optical filters. This limitation can be circumvented by utilizing the GHz-wide features of a Doppler broadened atomic gas. The anomalous dispersion of atomic vapours enables spectral filtering. These, so-called, Faraday anomalous dispersion optical filters (FADOFs) can be by far better than any commercial filter in terms of bandwidth, transition edge and peak transmission. We present a theoretical and experimental study on the transmission properties of a sodium vapour based FADOF with the aim to find the best combination of optical rotation and intrinsic loss. The relevant parameters, such as magnetic field, temperature, the related optical depth, and polarization state are discussed. The non-trivial interplay of these quantities defines the net performance of the filter. We determine analytically the optimal working conditions, such as transmission and the signal to background ratio and validate the results experimentally. We find a single global optimum for one specific optical path length of the filter. This can now be applied to spectroscopy, guide star applications, or sensing. PMID:25298251

Kiefer, Wilhelm; Löw, Robert; Wrachtrup, Jörg; Gerhardt, Ilja

2014-01-01

54

Na-Faraday rotation filtering: The optimal point  

PubMed Central

Narrow-band optical filtering is required in many spectroscopy applications to suppress unwanted background light. One example is quantum communication where the fidelity is often limited by the performance of the optical filters. This limitation can be circumvented by utilizing the GHz-wide features of a Doppler broadened atomic gas. The anomalous dispersion of atomic vapours enables spectral filtering. These, so-called, Faraday anomalous dispersion optical filters (FADOFs) can be by far better than any commercial filter in terms of bandwidth, transition edge and peak transmission. We present a theoretical and experimental study on the transmission properties of a sodium vapour based FADOF with the aim to find the best combination of optical rotation and intrinsic loss. The relevant parameters, such as magnetic field, temperature, the related optical depth, and polarization state are discussed. The non-trivial interplay of these quantities defines the net performance of the filter. We determine analytically the optimal working conditions, such as transmission and the signal to background ratio and validate the results experimentally. We find a single global optimum for one specific optical path length of the filter. This can now be applied to spectroscopy, guide star applications, or sensing. PMID:25298251

Kiefer, Wilhelm; Low, Robert; Wrachtrup, Jorg; Gerhardt, Ilja

2014-01-01

55

Two-step intensity modulated arc therapy (2-step IMAT) with segment weight and width optimization  

PubMed Central

Background 2-step intensity modulated arc therapy (IMAT) is a simplified IMAT technique which delivers the treatment over typically two continuous gantry rotations. The aim of this work was to implement the technique into a computerized treatment planning system and to develop an approach to optimize the segment weights and widths. Methods 2-step IMAT was implemented into the Prism treatment planning system. A graphical user interface was developed to generate the plan segments automatically based on the anatomy in the beam's-eye-view. The segment weights and widths of 2-step IMAT plans were subsequently determined in Matlab using a dose-volume based optimization process. The implementation was tested on a geometric phantom with a horseshoe shaped target volume and then applied to a clinical paraspinal tumour case. Results The phantom study verified the correctness of the implementation and showed a considerable improvement over a non-modulated arc. Further improvements in the target dose uniformity after the optimization of 2-step IMAT plans were observed for both the phantom and clinical cases. For the clinical case, optimizing the segment weights and widths reduced the maximum dose from 114% of the prescribed dose to 107% and increased the minimum dose from 87% to 97%. This resulted in an improvement in the homogeneity index of the target dose for the clinical case from 1.31 to 1.11. Additionally, the high dose volume V105 was reduced from 57% to 7% while the maximum dose in the organ-at-risk was decreased by 2%. Conclusions The intuitive and automatic planning process implemented in this study increases the prospect of the practical use of 2-step IMAT. This work has shown that 2-step IMAT is a viable technique able to achieve highly conformal plans for concave target volumes with the optimization of the segment weights and widths. Future work will include planning comparisons of the 2-step IMAT implementation with fixed gantry intensity modulated radiotherapy (IMRT) and commercial IMAT implementations. PMID:21631957

2011-01-01

56

Degeneracy, frequency response and filtering in IMRT optimization.  

PubMed

This paper attempts to provide an answer to some questions that remain either poorly understood, or not well documented in the literature, on basic issues related to intensity modulated radiation therapy (IMRT). The questions examined are: the relationship between degeneracy and frequency response of optimizations, effects of initial beamlet fluence assignment and stopping point, what does filtering of an optimized beamlet map actually do and how could image analysis help to obtain better optimizations? Two target functions are studied, a quadratic cost function and the log likelihood function of the dynamically penalized likelihood (DPL) algorithm. The algorithms used are the conjugate gradient, the stochastic adaptive simulated annealing and the DPL. One simple phantom is used to show the development of the analysis tools used and two clinical cases of medium and large dose matrix size (a meningioma and a prostate) are studied in detail. The conclusions reached are that the high number of iterations that is needed to avoid degeneracy is not warranted in clinical practice, as the quality of the optimizations, as judged by the DVHs and dose distributions obtained, does not improve significantly after a certain point. It is also shown that the optimum initial beamlet fluence assignment for analytical iterative algorithms is a uniform distribution, but such an assignment does not help a stochastic method of optimization. Stopping points for the studied algorithms are discussed and the deterioration of DVH characteristics with filtering is shown to be partially recoverable by the use of space-variant filtering techniques. PMID:15285252

Llacer, Jorge; Agazaryan, Nzhde; Solberg, Timothy D; Promberger, Claus

2004-07-01

57

OpenFilters: open-source software for the design, optimization, and synthesis of optical filters.  

PubMed

The design of optical filters relies on powerful computer-assisted methods. Many of these methods are provided by commercial programs, but, in order to adapt and improve them, or to develop new methods, one needs to create his own software. To help people interested in such a process, we decided to release our in-house software, called OpenFilters, under the GNU General Public License, an open-source license. It is programmed in Python and C++, and the graphical user interface is implemented with wxPython. It allows creation of multilayer and graded-index filters and calculation of reflection, transmission, absorption, phase, group delay, group delay dispersion, color, ellipsometric variables, admittance diagram, circle diagram, electric field distribution, and generation of reflection, transmission, and ellipsometric monitoring curves. It also provides the refinement, needle, step, and Fourier transform methods. PMID:18449250

Larouche, Stéphane; Martinu, Ludvik

2008-05-01

58

A multi-dimensional procedure for BNCT filter optimization  

SciTech Connect

An initial version of an optimization code utilizing two-dimensional radiation transport methods has been completed. This code is capable of predicting material compositions of a beam tube-filter geometry which can be used in a boron neutron capture therapy treatment facility to improve the ratio of the average radiation dose in a brain tumor to that in the healthy tissue surrounding the tumor. The optimization algorithm employed by the code is very straightforward. After an estimate of the gradient of the dose ratio with respect to the nuclide densities in the beam tube-filter geometry is obtained, changes in the nuclide densities are made based on: (1) the magnitude and sign of the components of the dose ratio gradient, (2) the magnitude of the nuclide densities, (3) the upper and lower bound of each nuclide density, and (4) the linear constraint that the sum of the nuclide density fractions in each material zone be less than or equal to 1.0. A local optimal solution is assumed to be found when one of the following conditions is satisfied in every material zone: (1) the maximum positive component of the gradient corresponds to a nuclide at its maximum density and the sum of the density fractions equals 1.0 or, and (2) the positive and negative components of the gradient correspond to nuclides densities at their upper and lower bounds, respectively, and the remaining components of the gradient are sufficiently small. The optimization procedure has been applied to a beam tube-filter geometry coupled to a simple tumor-patient head model and an improvement of 50% in the dose ratio was obtained.

Lille, R.A.

1998-02-01

59

Optimal Nonnegative Color Scanning Filters Gaurav Sharma \\Lambda H. Joel Trussell y Michael J. Vrhel z  

E-print Network

. Vrhel z Abstract In this correspondence, the problem of designing color scanning filters for multiOptimal Nonnegative Color Scanning Filters Gaurav Sharma \\Lambda H. Joel Trussell y Michael J­form solutions for optimal scanning filters at various signal­to­noise ratios (SNRs) were determined, \\Lambda

Sharma, Gaurav

60

A nearly optimal variable fractional delay filter with extracted Chebyshev window  

Microsoft Academic Search

A novel technique for designing a nearly optimal (in the Chebyshev sense) FIR variable fractional delay filter is presented that offers rapid recalculation of the filter coefficients according to the varying fractional delay parameter. The idea of the technique lies in using a fixed window extracted from a strictly optimal linear-phase design and in updating the filter coefficients in a

Ewa Hermanowicz

1998-01-01

61

Optimization of adenovirus 40 and 41 recovery from tap water using small disk filters.  

PubMed

Currently, the U.S. Environmental Protection Agency's Information Collection Rule (ICR) for the primary concentration of viruses from drinking and surface waters uses the 1MDS filter, but a more cost effective option, the NanoCeram® filter, has been shown to recover comparable levels of enterovirus and norovirus from both matrices. In order to achieve the highest viral recoveries, filtration methods require the identification of optimal concentration conditions that are unique for each virus type. This study evaluated the effectiveness of 1MDS and NanoCeram filters in recovering adenovirus (AdV) 40 and 41 from tap water, and optimized two secondary concentration procedures the celite and organic flocculation method. Adjustments in pH were made to both virus elution solutions and sample matrices to determine which resulted in higher virus recovery. Samples were analyzed by quantitative PCR (qPCR) and Most Probable Number (MPN) techniques and AdV recoveries were determined by comparing levels of virus in sample concentrates to that in the initial input. The recovery of adenovirus was highest for samples in unconditioned tap water (pH 8) using the 1MDS filter and celite for secondary concentration. Elution buffer containing 0.1% sodium polyphosphate at pH 10.0 was determined to be most effective overall for both AdV types. Under these conditions, the average recovery for AdV40 and 41 was 49% and 60%, respectively. By optimizing secondary elution steps, AdV recovery from tap water could be improved at least two-fold compared to the currently used methodology. Identification of the optimal concentration conditions for human AdV (HAdV) is important for timely and sensitive detection of these viruses from both surface and drinking waters. PMID:23796954

McMinn, Brian R

2013-11-01

62

Neuromuscular fiber segmentation through particle filtering and discrete optimization  

NASA Astrophysics Data System (ADS)

We present an algorithm to segment a set of parallel, intertwined and bifurcating fibers from 3D images, targeted for the identification of neuronal fibers in very large sets of 3D confocal microscopy images. The method consists of preprocessing, local calculation of fiber probabilities, seed detection, tracking by particle filtering, global supervised seed clustering and final voxel segmentation. The preprocessing uses a novel random local probability filtering (RLPF). The fiber probabilities computation is performed by means of SVM using steerable filters and the RLPF outputs as features. The global segmentation is solved by discrete optimization. The combination of global and local approaches makes the segmentation robust, yet the individual data blocks can be processed sequentially, limiting memory consumption. The method is automatic but efficient manual interactions are possible if needed. The method is validated on the Neuromuscular Projection Fibers dataset from the Diadem Challenge. On the 15 first blocks present, our method has a 99.4% detection rate. We also compare our segmentation results to a state-of-the-art method. On average, the performances of our method are either higher or equivalent to that of the state-of-the-art method but less user interactions is needed in our approach.

Dietenbeck, Thomas; Varray, François; Kybic, Jan; Basset, Olivier; Cachard, Christian

2014-03-01

63

Design of application specific long period waveguide grating filters using adaptive particle swarm optimization algorithms  

NASA Astrophysics Data System (ADS)

We present design optimization of wavelength filters based on long period waveguide gratings (LPWGs) using the adaptive particle swarm optimization (APSO) technique. We demonstrate optimization of the LPWG parameters for single-band, wide-band and dual-band rejection filters for testing the convergence of APSO algorithms. After convergence tests on the algorithms, the optimization technique has been implemented to design more complicated application specific filters such as erbium doped fiber amplifier (EDFA) amplified spontaneous emission (ASE) flattening, erbium doped waveguide amplifier (EDWA) gain flattening and pre-defined broadband rejection filters. The technique is useful for designing and optimizing the parameters of LPWGs to achieve complicated application specific spectra.

Semwal, Girish; Rastogi, Vipul

2014-01-01

64

An optimal nonorthogonal separation of the anisotropic Gaussian convolution filter.  

PubMed

We give an analytical and geometrical treatment of what it means to separate a Gaussian kernel along arbitrary axes in R(n), and we present a separation scheme that allows us to efficiently implement anisotropic Gaussian convolution filters for data of arbitrary dimensionality. Based on our previous analysis we show that this scheme is optimal with regard to the number of memory accesses and interpolation operations needed. The proposed method relies on nonorthogonal convolution axes and works completely in image space. Thus, it avoids the need for a fast Fourier transform (FFT)-subroutine. Depending on the accuracy and speed requirements, different interpolation schemes and methods to implement the one-dimensional Gaussian (finite impulse response and infinite impulse response) can be integrated. Special emphasis is put on analyzing the performance and accuracy of the new method. In particular, we show that without any special optimization of the source code, it can perform anisotropic Gaussian filtering faster than methods relying on the FFT. PMID:17076408

Lampert, Christoph H; Wirjadi, Oliver

2006-11-01

65

Optimization of counting times for short-lived gamma-ray emitters in air filter samples.  

PubMed

A methodology for the optimization of the counting times in a series of measurements of gamma-ray emitters in air filters is presented. In the optimal measurement regime in measurements of all the filters in a batch, the same minimum detectable activity is attained. It is shown how the number of filters, the properties of the gamma-ray emitter and the equipment influence the measurement time of the batch of filters and the minimum detectable activity attained. PMID:16554169

Korun, M

2006-01-01

66

Optimizing the use of inferior vena cava filters in oncology patients: are all filters created equally?  

PubMed

Many studies have supported the efficacy of inferior vena cava filters (IVCF) in the setting of venous thromboembolic disease, particularly in oncologic patients who are at increased risk. The advent of retrievable IVCF designs has prompted dramatically expanded use for patients with widely accepted indications but also disproportionately so in patients with so-called extended indications. At the same time, an alarming increase in filter-related complications has been reported both in the literature and through regulatory agencies, leading to government agency-issued warnings. The synergistic effect of these two interconnected phenomena is explained through a careful review of the evolution of IVCF device design. Critical differences exist when comparing retrievable IVCF and permanent IVCF. IVCF utilization can be optimized by prospectively identifying which patients are best served by a specific IVCF device. Careful follow-up strategies are also needed to ensure that all IVCFs are removed as soon as they are no longer needed. Finally, adjunctive techniques for removing "difficult" filters help maximize the number of IVCF removed and minimize IVCF left implanted needlessly. PMID:24610401

Ryu, Robert K; Lewandowski, Robert J

2014-04-01

67

[Characteristic wavelength variable optimization of near-infrared spectroscopy based on Kalman filtering].  

PubMed

Combining classical Kalman filter with NIR analysis technology, a new method of characteristic wavelength variable selection, namely Kalman filtering method, is presented. The principle of Kalman filter for selecting optimal wavelength variable was analyzed. The wavelength selection algorithm was designed and applied to NIR detection of soybean oil acid value. First, the PLS (partial leastsquares) models were established by using different absorption bands of oil. The 4 472-5 000 cm(-1) characteristic band of oil acid value, including 132 wavelengths, was selected preliminarily. Then the Kalman filter was used to select characteristic wavelengths further. The PLS calibration model was established using selected 22 characteristic wavelength variables, the determination coefficient R2 of prediction set and RMSEP (root mean squared error of prediction) are 0.970 8 and 0.125 4 respectively, equivalent to that of 132 wavelengths, however, the number of wavelength variables was reduced to 16.67%. This algorithm is deterministic iteration, without complex parameters setting and randomicity of variable selection, and its physical significance was well defined. The modeling using a few selected characteristic wavelength variables which affected modeling effect heavily, instead of total spectrum, can make the complexity of model decreased, meanwhile the robustness of model improved. The research offered important reference for developing special oil near infrared spectroscopy analysis instruments on next step. PMID:25007608

Wang, Li-Qi; Ge, Hui-Fang; Li, Gui-Bin; Yu, Dian-Yu; Hu, Li-Zhi; Jiang, Lian-Zhou

2014-04-01

68

Equal correlation peak optimization of the filter-feature-based synthetic discriminant reference image  

NASA Astrophysics Data System (ADS)

A modified equal correlation peak (ECP) optimization is proposed and introduced into the filter-feature-based joint transform correlator (FFB JTC) used for distortion-invariant pattern recognition. Instead of one fixed and arbitrarily chosen point in the classical ECP optimization, the maximum point in the correlation output plane is selected in our method. The modified ECP optimization is quite efficient when involving filter modulation. When compared with other ECP optimization methods related to the filter-modulation, our optimization method is linear and can easily obtain an exact solution. Simulation results show that after ECP optimization the stability of the correlation output of the FFB JTC may be greatly improved.

Zhong, Sheng; Liu, Shutian; Zhang, Xueru; Li, Chunfei

1998-02-01

69

Sparsity Optimization in Design of Multidimensional Filter Networks  

E-print Network

filters whose low sparsity ensures fast image processing. The filter network ..... solves, for alternating index j, the linear least-squares problem that consists in minimizing ..... the speed-up in the signal processing time provided by filter networks.

2014-02-02

70

Polymer Optimization of Pigmented Photoresists for Color Filter Production  

NASA Astrophysics Data System (ADS)

The lithographic performance of pigmented photoresists for color filter production is affected by the structure of the employed polymer. Four polymers with acrylate backbones and pendant reactive acrylate/methacrylate groups were prepared, and the effects of their molecular weights and acid values on the pixel pattern quality, development time, sensitivity and development mode were elucidated. ECHIPTM, a statistical experimental design program was used for optimization studies revealing that the red resist performs best, when polymers with relatively low acid values (<40 mg KOH/g polymer) and high molecular weights >50,000 are used. The green and the blue resists yielded optimal patterns at molecular weights in the range of 20,000 30,000 with acid values of about 50 60 mg KOH/g polymer. The sensitivity of resists containing polymers with pendant acryloyl groups is in general higher than that of the corresponding methacryloyl derivatives. Polymers having butyl acrylate-methacrylic acid backbone units showed the highest sensitivity among the polymers investigated. When developed with an optimized tetramethyl ammonium hydroxide (TMAH) based developer, resists using polymers with methyl methacrylate units showed peeling type development, while butyl acrylate copolymers effected homogeneous dissolution yielding higher resolution.

Kudo, Takanori; Nanjo, Yuki; Nozaki, Yuko; Yamaguchi, Hidemasa; Kang, Wen-Bing; Pawlowski, Georg

1998-03-01

71

Two-step Design of Pre-filter and Post-filter for AD/DA Converter  

NASA Astrophysics Data System (ADS)

In the field of signal processing, AD/DA converter takes an important role for data compressing and circuits design. This paper proposes new design method of AD/DA system with pre-filter and post-filters for achieving small quantization noise effect. Both filters are designed to minimize noise and distortion toward original signal. The effectiveness is illustrated by numerical example.

Okajima, Hiroshi; Matsunaga, Nobutomo

72

Filtering by optimal projection and application to automatic artifact removal from EEG  

Microsoft Academic Search

A new approach to filter multi-channel signals is presented, called filtering by optimal projection (FOP) in this paper. This approach is based on common spatial subspace decomposition (CSSD) theory. Moreover, an evolution of this method for non-stationary signals is also introduced which is called adaptative FOP (AFOP). As ICA, a filtering matrix is set up in the best way to

Samuel Boudet; Laurent Peyrodie; Philippe Gallois; Christian Vasseur

2007-01-01

73

A Triple-band Bandpass Filter using Tri-section Step-impedance and Capacitively Loaded Step-impedance Resonators for GSM, WiMAX, and WLAN systems  

NASA Astrophysics Data System (ADS)

This paper presents a triple-band bandpass filter for applications of GSM, WiMAX, and WLAN systems. The proposed filter comprises of the tri-section step-impedance and capacitively loaded step-impedance resonators, which are combined using the cross coupling technique. Additionally, tapered lines are used to connect at both ports of the filter in order to enhance matching for the tri-band resonant frequencies. The filter can operate at the resonant frequencies of 1.8 GHz, 3.7 GHz, and 5.5 GHz. At resonant frequencies, the measured values of S11 are -17.2 dB, -33.6 dB, and -17.9 dB, while the measured values of S21 are -2.23 dB, -2.98 dB, and -3.31 dB, respectively. Moreover, the presented filter has compact size compared with the conventional open-loop cross coupling triple band bandpass filters

Chomtong, P.; Akkaraekthalin, P.

2014-05-01

74

Fuzzy membership function optimization for system identification using an extended Kalman filter  

E-print Network

Fuzzy membership function optimization for system identification using an extended Kalman filter an extended Kalman filter to optimize the membership functions for system modeling, or system identification identification. The ideas described in this paper are illustrated for system identification of a nonlinear

Simon, Dan

75

Resolving power and encircled energy in aberrated optical systems with filters optimized for the Strehl ratio  

Microsoft Academic Search

Results of the optimization of the axial response of optical systems by filters of non-uniform transmission are presented. Optical systems with different types of residual aberrations are studied. The image quality criterion considered in the optimization procedure is the Strehl Ratio (SR). The effect of these filters on the point spread function (PSF), the resolving power and the encircled energy

J. Campos; F. Calvo; M. J. Yzuel

1988-01-01

76

Annealed particle filter based on particle swarm optimization for articulated three-dimensional human motion tracking  

NASA Astrophysics Data System (ADS)

Three-dimensional articulated human motion tracking is challenging due to the high-dimensional parameter space and poor image observations. When particle swarm optimization (PSO) is used for human motion tracking, due to unreliable image likelihood, particles may be misled and be unable to find the most plausible pose space. This paper proposes a new PSO-based algorithm for human motion tracking, annealed PSO-based particle filter (APSOPF). The sampling covariance and annealing factor are incorporated into the velocity-updating equation of PSO; they are initialized with appropriate values at the beginning of the PSO iteration, and decreased (annealed) in reasonable steps. Through the sampling covariance, the motion prior is introduced into APSOPF, constraining particles to the most likely region of pose space and reducing the generation of invalid particles. By adopting decreasing coefficients in the updating principle, the leading effects of the local and global best on particles decrease with generations, making particles preserve their own divergence and self-exploration capabilities before convergence. Hence the problem of insufficiently reliable image likelihood can be mitigated in some degree. We compare APSOPF quantitatively with an annealed particle filter and a standard particle filter on the challenging HumanEvaI data set. Experimental results show that the proposed algorithm achieves lower estimation error in tracking real-world 3-D human motion.

Wang, Xiangyang; Wan, Wanggen; Zhang, Xiaoqin; Yu, Xiaoqing

2010-01-01

77

Research on Optimal Sensor Placement Using Effective Two-Step Arrangement Approach  

Microsoft Academic Search

Optimal sensor placement method is very important in structural vibration test. This paper proposes an effective two-step arrangement method for sensors optimization, which is suitable for on-line monitoring scheme. In the first step, we calculate the utmost distance of sensors on a special structure by principle of elastic wave propagation and determine the preliminary number of sensors; in the second

Ziyan Wu; Haifeng Yang; Yunju Yan

2009-01-01

78

Application of Maximum Likelihood Ensemble Filter (MLEF) With a Parameterized Chemistry Transport Model (PCTM) to Optimize Surface CO2 Fluxes  

NASA Astrophysics Data System (ADS)

Inverse modeling is widely used to optimize surface CO2 fluxes using observed CO2 concentrations in the atmosphere. A number of methods have been employed in inverse problems in geophysical research. Toward this goal, we apply the Maximum Likelihood Ensemble Filter (MLEF) algorithm, developed at Colorado State University. This is a novel ensemble filter approach, defined taking into account the experience (in terms of advantages and disadvantages) from Variational Methods, the Iterated Kalman Filter, and the Ensemble Trasform Kalman Filter. The MLEF is used with an offline chemistry/transport model (PCTM) to optimize the surface fluxes. To evaluate the technique, we ran the transport model with artificially generated CO2 observations sampled at CMDL flask locations by running the PCTM forward for four years with hourly CO2 fluxes generated by a terrestrial biosphere model (SiB) and monthly mean prescribed ocean fluxes. A time shifted true flux map was considered as the prior flux field for the assimilation step. Assimilation was done by using 8-12 week flux moving window and observations were assimilated at the end of the window. Spatial and temporal covariance in the retrieved fluxes are estimated by the optimization scheme by propagating the forecast error covariance forward through successive assimilation cycles. In the future, this technique will be implemented with real atmospheric observations.

Lokupitiya, R. S.; Denning, S.; Zupanski, D.; Gurney, K.; Zupanski, M.

2005-12-01

79

Thin film characterization for modeling and optimization of silver-dielectric color filters.  

PubMed

We investigate the most appropriate way to optically characterize the materials and predict the spectral responses of metal-dielectric filters in the visible range. Special attention is given to thin silver layers that have a major impact on the filter's spectral transmittance and reflectance. Two characterization approaches are compared, based either on single layers, or on multilayer stacks, in approaching the filter design. The second approach is preferred, because it gives the best way to predict filter characteristics. Meanwhile, it provides a stack model and dispersion relations that can be used for filter design optimization. PMID:24663425

Frey, Laurent; Parrein, Pascale; Virot, Léopold; Pellé, Catherine; Raby, Jacques

2014-03-10

80

Joint optimization of multiple behavioral and implementation properties of digital IIR filter designs  

Microsoft Academic Search

This paper presents an extensible framework for the simultaneous constrained optimization of multiple properties of digital IIR filters. The framework optimizes the pole-zero locations for behavioral properties of magnitude and phase response, and the implementation property of quality factors, subject to constraints on the same properties. We formulate the constrained nonlinear optimization problem as a sequential quadratic programming (SQP) problem.

M. Valliappan; Brian L. Evans; M. Gzara; M. D. Lutovac; D. V. Tosic

2000-01-01

81

BLIND CHANNEL EQUALIZATION WITH ALGEBRAIC OPTIMAL STEP SIZE  

Microsoft Academic Search

The constant modulus algorithm (CMA) is arguably the most widespread iterative method for blind equalization of digital communication channels. The present contribution studies a recently proposed technique aiming at avoiding the shortcomings of conventional gradient-descent implementa- tions. This technique is based on the computation of the step size leading to the absolute minimum of the CM crite- rion along the

Vicente Zarzoso; Pierre Comon

2005-01-01

82

Optimal and unbiased FIR filtering in discrete time state space with smoothing and predictive properties  

NASA Astrophysics Data System (ADS)

We address p-shift finite impulse response optimal (OFIR) and unbiased (UFIR) algorithms for predictive filtering ( p > 0), filtering ( p = 0), and smoothing filtering ( p < 0) at a discrete point n over N neighboring points. The algorithms were designed for linear time-invariant state-space signal models with white Gaussian noise. The OFIR filter self-determines the initial mean square state function by solving the discrete algebraic Riccati equation. The UFIR one represented both in the batch and iterative Kalman-like forms does not require the noise covariances and initial errors. An example of applications is given for smoothing and predictive filtering of a two-state polynomial model. Based upon this example, we show that exact optimality is redundant when N ? 1 and still a nice suboptimal estimate can fairly be provided with a UFIR filter at a much lower cost.

Shmaliy, Yuriy S.; Ibarra-Manzano, Oscar

2012-12-01

83

Optease Vena Cava Filter Optimal Indwelling Time and Retrievability  

SciTech Connect

The purpose of this study was to assess the indwelling time and retrievability of the Optease IVC filter. Between 2002 and 2009, a total of 811 Optease filters were inserted: 382 for prophylaxis in multitrauma patients and 429 for patients with venous thromboembolic (VTE) disease. In 139 patients [97 men and 42 women; mean age, 36 (range, 17-82) years], filter retrieval was attempted. They were divided into two groups to compare change in retrieval policy during the years: group A, 60 patients with filter retrievals performed before December 31 2006; and group B, 79 patients with filter retrievals from January 2007 to October 2009. A total of 128 filters were successfully removed (57 in group A, and 71 in group B). The mean filter indwelling time in the study group was 25 (range, 3-122) days. In group A the mean indwelling time was 18 (range, 7-55) days and in group B 31 days (range, 8-122). There were 11 retrieval failures: 4 for inability to engage the filter hook and 7 for inability to sheathe the filter due to intimal overgrowth. The mean indwelling time of group A retrieval failures was 16 (range, 15-18) days and in group B 54 (range, 17-122) days. Mean fluoroscopy time for successful retrieval was 3.5 (range, 1-16.6) min and for retrieval failures 25.2 (range, 7.2-62) min. Attempts to retrieve the Optease filter can be performed up to 60 days, but more failures will be encountered with this approach.

Rimon, Uri, E-mail: rimonu@sheba.health.gov.il; Bensaid, Paul, E-mail: paulbensaid@hotmail.com; Golan, Gil, E-mail: gilgolan201@gmail.com; Garniek, Alexander, E-mail: garniek@gmail.com; Khaitovich, Boris, E-mail: borislena@012.net.il [Chaim Sheba Medical Center (Affiliated to the Sackler School of Medicine, Tel-Aviv University, Tel-Aviv), Department of Diagnostic Imaging (Israel); Dotan, Zohar, E-mail: Zohar.Dotan@sheba.health.gov.il [Chaim Sheba Medical Center (Affiliated to the Sackler School of Medicine, Tel-Aviv University, Tel-Aviv), Department of Urology (Israel); Konen, Eli, E-mail: Eli.Konen@sheba.health.gov.il [Chaim Sheba Medical Center (Affiliated to the Sackler School of Medicine, Tel-Aviv University, Tel-Aviv), Department of Diagnostic Imaging (Israel)

2011-06-15

84

Treatment of domestic sewage in a two-step anaerobic filter\\/anaerobic hybrid system at low temperature  

Microsoft Academic Search

The treatment of domestic sewage at low temperature of 13°C was investigated in a two-step system consisting of an anaerobic filter (AF) +an anaerobic hybrid (AH) reactor operated at different hydraulic retention times (HRTs). The AF reactor was efficient in the removal of suspended COD, viz. 81%, 58% and 57% at an HRT of, respectively, 4, 2 and 3h. For

Tarek A. Elmitwalli; Kim L. T. Oahn; Grietje Zeeman; Gatze Lettinga

2002-01-01

85

Particle swarm optimization and its application to the design of diffraction grating filters  

NASA Astrophysics Data System (ADS)

Particle swarm optimization (PSO) is an evolutionary, easy-to-implement technique to design optical diffraction gratings. Design of reflection and transmission guided-mode resonance (GMR) grating filters using PSO is reported. The spectra of the designed filters are in good agreement with the design targets in a reasonable computation time. Also, filters are designed with a genetic algorithm (GA) and the results obtained by the GA and PSO are compared.

Shokooh-Saremi, Mehrdad; Magnusson, Robert

2007-04-01

86

Optimally designed narrowband guided-mode resonance reflectance filters for mid-infrared  

E-print Network

Optimally designed narrowband guided-mode resonance reflectance filters for mid-infrared mid-infrared reflectance filters based on guided-mode resonance (GMR) in waveguide gratings@illinois.edu Abstract: An alternative to the well-established Fourier transform infrared (FT-IR) spectrometry, termed

Cunningham, Brian

87

Structured design of a 288-tap FIR filter by optimized partial product tree compression  

Microsoft Academic Search

A compact 10-b, 288-tap finite impulse response (FIR) filter is designed by adopting structured architecture that employs an optimized partial product tree compression method. The new scheme is based on the addition of equally weighted partial products resulted from 288 multiplications of the filter coefficients and the inputs. The 288 multiplication and 287 addition operations are decomposed to add 1440

Jun Rim Choi; Lak Hyun Jang; Seong Wook Jung; Jin Ho Choi

1997-01-01

88

Environmentally realistic fingerprint-image generation with evolutionary filter-bank optimization  

E-print Network

Environmentally realistic fingerprint-image generation with evolutionary filter-bank optimization t i c l e i n f o Keywords: Fingerprint image generation Evolutionary algorithm Image filters Input pressure a b s t r a c t Constructing a fingerprint database is important to evaluate the performance

Cho, Sung-Bae

89

DMT bit rate maximization with optimal time domain equalizer filter bank architecture  

Microsoft Academic Search

In a multicarrier modulation system, a time domain equalizer (TEQ) traditionally shortens the transmission channel impulse response (CIR) to mitigate intersymbol interference (ISI). In this paper, we propose a data-rate optimal TEQ filter bank whose data rates at the equalizer output of this filter bank are significantly better than those of the Maximum Bit Rate and Minimum ISI methods and

Milos Milosevic; Lucio F. C. Pessoa; Brian L. Evans; Ross Baldick

2002-01-01

90

Speed estimation of an induction motor drive using an optimized extended Kalman filter  

Microsoft Academic Search

This paper presents a novel method to achieve good performance of an extended Kalman filter (EKF) for speed estimation of an induction motor drive. A real-coded genetic algorithm (GA) is used to optimize the noise covariance and weight matrices of the EKF, thereby ensuring filter stability and accuracy in speed estimation. Simulation studies on a constant V\\/Hz controller and a

K. L. Shi; T. F. Chan; Y. K. Wong; S. L. Ho

2002-01-01

91

Near-Optimal deterministic filtering on the Rotation Mohammad Zamani, Jochen Trumpf, Member, IEEE,  

E-print Network

1 Near-Optimal deterministic filtering on the Rotation Group Mohammad Zamani, Jochen Trumpf, Member are with the School of Engineering, Aus- tralian National University, Canberra, ACT, Australia. Mohammad.Zamani

Trumpf, Jochen

92

Optimal Filters with Multiple Packet Losses and its Application in Wireless Sensor Networks  

PubMed Central

This paper is concerned with the filtering problem for both discrete-time stochastic linear (DTSL) systems and discrete-time stochastic nonlinear (DTSN) systems. In DTSL systems, an linear optimal filter with multiple packet losses is designed based on the orthogonal principle analysis approach over unreliable wireless sensor networks (WSNs), and the experience result verifies feasibility and effectiveness of the proposed linear filter; in DTSN systems, an extended minimum variance filter with multiple packet losses is derived, and the filter is extended to the nonlinear case by the first order Taylor series approximation, which is successfully applied to unreliable WSNs. An application example is given and the corresponding simulation results show that, compared with extended Kalman filter (EKF), the proposed extended minimum variance filter is feasible and effective in WSNs. PMID:22319301

Liu, Yonggui; Xu, Bugong; Feng, Linfang; Li, Shanbin

2010-01-01

93

Comparison of optimal and local search methods for designing finite wordlength FIR digital filters  

NASA Astrophysics Data System (ADS)

This paper presents a comparison between an optimal (branch-and-bound) algorithm and a suboptimal (local search) algorithm for the design of finite wordlength finite-impulse-response (FIR) digital filters. Experimental results are described for 11 examples of length 15 to 35. It is concluded that when computer resources are not available for the optimal method, it is still worth applying the local search method to the filter with rounded coefficients.

Kodek, D.; Steiglitz, K.

1981-01-01

94

Optimized cut of LiTaO3 for resonator filters with improved performance  

Microsoft Academic Search

In resonator filters, it is often desirable to minimize propagation loss simultaneously at resonant and anti-resonant frequencies. Using this criterion, we found an optimal dependence of rotation angle on electrode thickness in wavelengths, in rotated YX cuts of LiTaO3 with At grating. In particular, 48°YX cut was found to be optimal for resonator filters with thick Al electrodes, about 10%

N. Naumenko; B. Abbot

2002-01-01

95

Optimizing a continuously variable filter in a hybrid optical correlator  

NASA Technical Reports Server (NTRS)

In contrast to binary filters, continuously variable optical filters offer an ability to conpensate for certain imperfections in the optics of a hybrid correlator. Arbitrary static phase errors are introduced into a model of a phase-only filtering hybrid correlator, and a method of discovering a correction for them simulated. By a recursive technique a first approximation to the impulse's matched filter is adjusted (allowed to relax) so as to produce successively more localized distribution of the output in the correlation plane. The method is motivated by the development of continuously-variable phase-only spatial light modulators, but it is applicable to amplitude modulators and -with appropriate modification -- to binary modulators as well. The technique is robust against the form of the system's departure from ideal behavior.

Juday, Richard D.

1987-01-01

96

Optimizing a continuously variable filter in a hybrid optical correlator  

NASA Astrophysics Data System (ADS)

In contrast to binary filters, continuously variable optical filters offer an ability to conpensate for certain imperfections in the optics of a hybrid correlator. Arbitrary static phase errors are introduced into a model of a phase-only filtering hybrid correlator, and a method of discovering a correction for them simulated. By a recursive technique a first approximation to the impulse's matched filter is adjusted (allowed to relax) so as to produce successively more localized distribution of the output in the correlation plane. The method is motivated by the development of continuously-variable phase-only spatial light modulators, but it is applicable to amplitude modulators and -with appropriate modification -- to binary modulators as well. The technique is robust against the form of the system's departure from ideal behavior.

Juday, Richard D.

97

Wide-Band Optical Filter Optimized for Deep Imaging of Small Solar System Bodies  

NASA Astrophysics Data System (ADS)

This paper describes a newly designed wide-band optical filter. It is optimized for deep imaging of small solar-system bodies. The new filter, which we denote as W i, is designed to reduce contamination by light pollution from street lamps, especially strong mercury and sodium emission lines. It is also useful for reducing unwanted scattered moonlight. Compared with the use of a commercially available long-wave cut wide-band filter, the signal-to-noise ratios in the detection of asteroids are improved by about 6% by using the W i filter.

Okumura, Shin-ichiro; Nishiyama, Kota; Urakawa, Seitaro; Sakamoto, Tsuyoshi; Takahashi, Noritsugu; Yoshikawa, Makoto

2012-06-01

98

Distributed optimal consensus filter for target tracking in heterogeneous sensor networks.  

PubMed

This paper is concerned with the problem of filter design for target tracking over sensor networks. Different from most existing works on sensor networks, we consider the heterogeneous sensor networks with two types of sensors different on processing abilities (denoted as type-I and type-II sensors, respectively). However, questions of how to deal with the heterogeneity of sensors and how to design a filter for target tracking over such kind of networks remain largely unexplored.We propose in this paper a novel distributed consensus filter to solve the target tracking problem. Two criteria, namely, unbiasedness and optimality, are imposed for the filter design. The so-called sequential design scheme is then presented to tackle the heterogeneity of sensors. The minimum principle of Pontryagin is adopted for type-I sensors to optimize the estimation errors. As for type-II sensors, the Lagrange multiplier method coupled with the generalized inverse of matrices is then used for filter optimization. Furthermore, it is proven that convergence property is guaranteed for the proposed consensus filter in the presence of process and measurement noise. Simulation results have validated the performance of the proposed filter. It is also demonstrated that the heterogeneous sensor networks with the proposed filter outperform the homogenous counterparts in light of reduction in the network cost, with slight degradation of estimation performance. PMID:23757586

Zhu, Shanying; Chen, Cailian; Li, Wenshuang; Yang, Bo; Guan, Xinping

2013-12-01

99

An optimal numerical filter for wide-field-of-view measurements of earth-emitted radiation  

NASA Technical Reports Server (NTRS)

A technique is described in which all data points along an arc of the orbit may be used in an optimal numerical filter for wide-field-of-view measurements of earth emitted radiation. The statistical filter design is derived whereby the filter is required to give a minimum variance estimate of the radiative exitance at discrete points along the ground track of the satellite. An equation for the optimal numerical filter is given by minimizing the estimate error variance equation with respect to the filter weights, resulting in a discrete form of the Wiener-Hopf equation. Finally, variances of the errors in the radiant exitance can be computed along the ground track and in the cross track directions.

Smith, G. L.; House, F. B.

1981-01-01

100

Optimization of multiplexed holographic gratings in PQ-PMMA for spectral-spatial imaging filters.  

PubMed

Holographic gratings formed in thick phenanthrenquinone- (PQ-) doped poly(methyl methacrylate) (PMMA) can be made to have narrowband spectral and spatial transmittance filtering properties. We present the design and performance of angle-multiplexed holographic filters formed in PQ-PMMA at 488 nm and reconstructed with a LED operated at approximately 630 nm. The dark delay time between exposure and the preillumination exposure of the polymer prior to exposure of the holographic area are varied to optimize the diffraction efficiency of multiplexed holographic filters. The resultant holographic filters can enhance the performance of four-dimensional spatial-spectral imaging systems. The optimized filters are used to simultaneously sample spatial and spectral information at five different depths separated by 50 microm within biological tissue samples. PMID:18347711

Luo, Yuan; Gelsinger, Paul J; Barton, Jennifer K; Barbastathis, George; Kostuk, Raymond K

2008-03-15

101

Single step optimization of feedback-decoupled collision avoidance manipulator maneuvers  

NASA Technical Reports Server (NTRS)

Simultaneous robot path planning and path following is shown to be achievable in the presence of motor saturation and obstacle avoidance requirements. The discrete time algorithm derived performs one step ahead mean square optimization of commanded joint accelerations, subject to present actuator force or torque constraints and N step ahead prediction of configuration constraints.

Chen, N.; Dwyer, T. A. W., III; Fadali, M. S.

1986-01-01

102

The design of an optimal filter for monthly GRACE gravity models  

NASA Astrophysics Data System (ADS)

Most applications of the publicly released Gravity Recovery and Climate Experiment monthly gravity field models require the application of a spatial filter to help suppressing noise and other systematic errors present in the data. The most common approach makes use of a simple Gaussian averaging process, which is often combined with a `destriping' technique in which coefficient correlations within a given degree are removed. As brute force methods, neither of these techniques takes into consideration the statistical information from the gravity solution itself and, while they perform well overall, they can often end up removing more signal than necessary. Other optimal filters have been proposed in the literature; however, none have attempted to make full use of all information available from the monthly solutions. By examining the underlying principles of filter design, a filter has been developed that incorporates the noise and full signal variance-covariance matrix to tailor the filter to the error characteristics of a particular monthly solution. The filter is both anisotropic and non-symmetric, meaning it can accommodate noise of an arbitrary shape, such as the characteristic stripes. The filter minimizes the mean-square error and, in this sense, can be considered as the most optimal filter possible. Through both simulated and real data scenarios, this improved filter will be shown to preserve the highest amount of gravity signal when compared to other standard techniques, while simultaneously minimizing leakage effects and producing smooth solutions in areas of low signal.

Klees, R.; Revtova, E. A.; Gunter, B. C.; Ditmar, P.; Oudman, E.; Winsemius, H. C.; Savenije, H. H. G.

2008-11-01

103

REDUCTION OF DESIGN STEPS FOR STACKED DIE QFN USING OPTIMIZATION TECHNIQUE  

Microsoft Academic Search

Taguchi method has been shown to be successful in optimizing design parameters in the manufacturing industry. Finite element (FE) simulation, on the other hand, is used as a design tool and helps to reduce design time and cost. In this paper, the finite element analysis and Taguchi method were combined to aid in the design steps and to optimize the

N. N. Bachok; M. Z. M. Talib; I. Ahmad; I. Abdullah

2008-01-01

104

Modeling the impact of drought on canopy carbon and water fluxes through parameter optimization using an ensemble Kalman filter  

NASA Astrophysics Data System (ADS)

Soil and atmospheric water deficits have significant influences on CO2 and energy exchanges between the atmosphere and terrestrial ecosystems. Model parameterization significantly affects the ability of a model to simulate carbon, water, and energy fluxes. In this study, an ensemble Kalman filter (EnKF) and observations of gross primary productivity (GPP) and latent heat (LE) fluxes were used to optimize model parameters significantly affecting the calculation of these fluxes for a subtropical coniferous plantation in southeastern China. The optimized parameters include the maximum carboxylation rate (Vcmax), the Ball-Berry coefficient (m) and the coefficient determining the sensitivity of stomatal conductance to atmospheric water vapor deficit D0). Optimized Vcmax and m showed larger seasonal and interannual variations than D0. Seasonal variations of Vcmax and m are more pronounced than the interannual variations. Vcmax and m are associated with soil water content (SWC). During dry periods, SWC at the 20 cm depth can explain 61% and 64% of variations of Vcmax and m, respectively. EnKF parameter optimization improves the simulations of GPP, LE and sensible heat (SH), mainly during dry periods. After parameter optimization using EnKF, the variations of GPP, LE and SH explained by the model increased by 1% to 4% at half-hourly steps and by 3% to 5% at daily time steps. Efforts are needed to develop algorithms that can properly describe the variations of these parameters under different environmental conditions.

Ju, W.; Wang, S.; Yu, G.; Zhou, Y.; Wang, H.

2009-08-01

105

A Dwindling Filter Line Search Method for Unconstrained Optimization  

E-print Network

multidimensional filter technique, which is a modification and improvement of .... Suppose that f(x) is an one-variable function, i.e., n = 1, and assume that xk belongs to ..... linear feasibility problems, Report 03/17, Dept of Mathematics, FUNDP, ...

2011-01-12

106

On-road vehicle detection using evolutionary Gabor filter optimization  

Microsoft Academic Search

Past work on vehicle detection has emphasized the issues of feature extraction and classification, however, less attention has been given on the critical issue of feature selection. The focus of this paper is on improving the performance of on-road vehicle detection by employing a set of Gabor filters that have been specifically customized for the problem of vehicle detection. The

Zehang Sun; George Bebis; Ronald Miller

2005-01-01

107

Polymer Optimization of Pigmented Photoresists for Color Filter Production  

Microsoft Academic Search

The lithographic performance of pigmented photoresists for color filter production is affected by the structure of the employed polymer. Four polymers with acrylate backbones and pendant reactive acrylate\\/methacrylate groups were prepared, and the effects of their molecular weights and acid values on the pixel pattern quality, development time, sensitivity and development mode were elucidated. ECHIPTM, a statistical experimental design program

Takanori Kudo; Yuki Nanjo; Yuko Nozaki; Hidemasa Yamaguchi; Wen-Bing Kang; Georg Pawlowski

1998-01-01

108

Linear adaptive noise-reduction filters for tomographic imaging: Optimizing for minimum mean square error  

SciTech Connect

This thesis solves the problem of finding the optimal linear noise-reduction filter for linear tomographic image reconstruction. The optimization is data dependent and results in minimizing the mean-square error of the reconstructed image. The error is defined as the difference between the result and the best possible reconstruction. Applications for the optimal filter include reconstructions of positron emission tomographic (PET), X-ray computed tomographic, single-photon emission tomographic, and nuclear magnetic resonance imaging. Using high resolution PET as an example, the optimal filter is derived and presented for the convolution backprojection, Moore-Penrose pseudoinverse, and the natural-pixel basis set reconstruction methods. Simulations and experimental results are presented for the convolution backprojection method.

Sun, W.Y. [Lawrence Berkeley Lab., CA (United States)]|[California Univ., Berkeley, CA (United States). Dept. of Electrical Engineering and Computer Sciences

1993-04-01

109

Optimally designed narrowband guided-mode resonance reflectance filters for mid-infrared spectroscopy.  

PubMed

An alternative to the well-established Fourier transform infrared (FT-IR) spectrometry, termed discrete frequency infrared (DFIR) spectrometry, has recently been proposed. This approach uses narrowband mid-infrared reflectance filters based on guided-mode resonance (GMR) in waveguide gratings, but filters designed and fabricated have not attained the spectral selectivity (? 32 cm(-1)) commonly employed for measurements of condensed matter using FT-IR spectroscopy. With the incorporation of dispersion and optical absorption of materials, we present here optimal design of double-layer surface-relief silicon nitride-based GMR filters in the mid-IR for various narrow bandwidths below 32 cm(-1). Both shift of the filter resonance wavelengths arising from the dispersion effect and reduction of peak reflection efficiency and electric field enhancement due to the absorption effect show that the optical characteristics of materials must be taken into consideration rigorously for accurate design of narrowband GMR filters. By incorporating considerations for background reflections, the optimally designed GMR filters can have bandwidth narrower than the designed filter by the antireflection equivalence method based on the same index modulation magnitude, without sacrificing low sideband reflections near resonance. The reported work will enable use of GMR filters-based instrumentation for common measurements of condensed matter, including tissues and polymer samples. PMID:22109445

Liu, Jui-Nung; Schulmerich, Matthew V; Bhargava, Rohit; Cunningham, Brian T

2011-11-21

110

Optimally designed narrowband guided-mode resonance reflectance filters for mid-infrared spectroscopy  

PubMed Central

An alternative to the well-established Fourier transform infrared (FT-IR) spectrometry, termed discrete frequency infrared (DFIR) spectrometry, has recently been proposed. This approach uses narrowband mid-infrared reflectance filters based on guided-mode resonance (GMR) in waveguide gratings, but filters designed and fabricated have not attained the spectral selectivity (? 32 cm?1) commonly employed for measurements of condensed matter using FT-IR spectroscopy. With the incorporation of dispersion and optical absorption of materials, we present here optimal design of double-layer surface-relief silicon nitride-based GMR filters in the mid-IR for various narrow bandwidths below 32 cm?1. Both shift of the filter resonance wavelengths arising from the dispersion effect and reduction of peak reflection efficiency and electric field enhancement due to the absorption effect show that the optical characteristics of materials must be taken into consideration rigorously for accurate design of narrowband GMR filters. By incorporating considerations for background reflections, the optimally designed GMR filters can have bandwidth narrower than the designed filter by the antireflection equivalence method based on the same index modulation magnitude, without sacrificing low sideband reflections near resonance. The reported work will enable use of GMR filters-based instrumentation for common measurements of condensed matter, including tissues and polymer samples. PMID:22109445

Liu, Jui-Nung; Schulmerich, Matthew V.; Bhargava, Rohit; Cunningham, Brian T.

2011-01-01

111

Realization of variable low-pass state-space digital filters using step responses  

Microsoft Academic Search

This paper presents a new realization method of variable low-pass infinite impulse response (IIR) digital filters with high tuning accuracy. We construct the proposed variable filters by using the state-space-based frequency transformation proposed by Mullis and Roberts. Since this transformation requires an inverse matrix that leads to high computational cost, we present a new simple algorithm that obtains this inverse

Shunsuke Koshita; Masahide Abe; Masayuki Kawamata

2010-01-01

112

Design of multichannel DWDM fiber Bragg grating filters by Lagrange multiplier constrained optimization.  

PubMed

We present the synthesis of multi-channel fiber Bragg grating (MCFBG) filters for dense wavelength-division-multiplexing (DWDM) application by using a simple optimization approach based on a Lagrange multiplier optimization (LMO) method. We demonstrate for the first time that the LMO method can be used to constrain various parameters of the designed MCFBG filters for practical application demands and fabrication requirements. The designed filters have a number of merits, i.e., flat-top and low dispersion spectral response as well as single stage. Above all, the maximum amplitude of the index modulation profiles of the designed MCFBGs can be substantially reduced under the applied constrained condition. The simulation results demonstrate that the LMO algorithm can provide a potential alternative for complex fiber grating filter design problems. PMID:19529515

Lee, Cheng-Ling; Lee, Ray-Kuang; Kao, Yee-Mou

2006-11-13

113

Facial recognition using composite correlation filters designed with multiobjective combinatorial optimization  

NASA Astrophysics Data System (ADS)

Facial recognition is a difficult task due to variations in pose and facial expressions, as well as presence of noise and clutter in captured face images. In this work, we address facial recognition by means of composite correlation filters designed with multi-objective combinatorial optimization. Given a large set of available face images having variations in pose, gesticulations, and global illumination, a proposed algorithm synthesizes composite correlation filters by optimization of several performance criteria. The resultant filters are able to reliably detect and correctly classify face images of different subjects even when they are corrupted with additive noise and nonhomogeneous illumination. Computer simulation results obtained with the proposed approach are presented and discussed in terms of efficiency in face detection and reliability of facial classification. These results are also compared with those obtained with existing composite filters.

Cuevas, Andres; Diaz-Ramirez, Victor H.; Kober, Vitaly; Trujillo, Leonardo

2014-09-01

114

On the application of optimal wavelet filter banks for ECG signal classification  

NASA Astrophysics Data System (ADS)

This paper discusses ECG signal classification after parametrizing the ECG waveforms in the wavelet domain. Signal decomposition using perfect reconstruction quadrature mirror filter banks can provide a very parsimonious representation of ECG signals. In the current work, the filter parameters are adjusted by a numerical optimization algorithm in order to minimize a cost function associated to the filter cut-off sharpness. The goal consists of achieving a better compromise between frequency selectivity and time resolution at each decomposition level than standard orthogonal filter banks such as those of the Daubechies and Coiflet families. Our aim is to optimally decompose the signals in the wavelet domain so that they can be subsequently used as inputs for training to a neural network classifier.

Hadjiloucas, S.; Jannah, N.; Hwang, F.; Galvão, R. K. H.

2014-03-01

115

FPGA Implementation of Optimal Filtering Algorithm for TileCal ROD System  

E-print Network

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.

Torres, J; Castillo, V; Cuenca, C; Ferrer, A; Fullana, E; González, V; Higón, E; Poveda, J; Ruiz-Martinez, A; Salvachúa, B; Sanchis, E; Solans, C; Valero, A; Valls, J A

2008-01-01

116

Near-Optimal Deterministic Attitude Filtering Mohammad Zamani, Jochen Trumpf, Member, IEEE, and Robert Mahony, Senior Member, IEEE  

E-print Network

Near-Optimal Deterministic Attitude Filtering Mohammad Zamani, Jochen Trumpf, Member, IEEE are with the School of Engineering, Australian National University, Canberra, ACT, Australia. Mohammad.Zamani

Trumpf, Jochen

117

Modeling a Dynamic Design System Using the Mahalanobis Taguchi System - Two-Step Optimal Algorithm  

Microsoft Academic Search

\\u000a This work presents a novel algorithm, the Mahalanobis Taguchi System- Two Step Optimal algorithm (MTS-TSO), which combines\\u000a the Mahalanobis Taguchi System (MTS) and Two-Step Optimal (TSO) algorithm for parameter selection of product design, and parameter\\u000a adjustment under the dynamic service industry environments.\\u000a \\u000a \\u000a From the results of the confirm experiment, a service industry company is adopted to applies in the methodology,

Tsung-Shin Hsu; Ching-Lien Huang

2010-01-01

118

Optimal filter parameters for low SNR seismograms as a function of station and event location  

NASA Astrophysics Data System (ADS)

Global seismic monitoring requires deployment of seismic sensors worldwide, in many areas that have not been studied or have few useable recordings. Using events with lower signal-to-noise ratios (SNR) would increase the amount of data from these regions. Lower SNR events can add significant numbers to data sets, but recordings of these events must be carefully filtered. For a given region, conventional methods of filter selection can be quite subjective and may require intensive analysis of many events. To reduce this laborious process, we have developed an automated method to provide optimal filters for low SNR regional or teleseismic events. As seismic signals are often localized in frequency and time with distinct time-frequency characteristics, our method is based on the decomposition of a time series into a set of subsignals, each representing a band with f/? f constant (constant Q). The SNR is calculated on the pre-event noise and signal window. The band pass signals with high SNR are used to indicate the cutoff filter limits for the optimized filter. Results indicate a significant improvement in SNR, particularly for low SNR events. The method provides an optimum filter which can be immediately applied to unknown regions. The filtered signals are used to map the seismic frequency response of a region and may provide improvements in travel-time picking, azimuth estimation, regional characterization, and event detection. For example, when an event is detected and a preliminary location is determined, the computer could automatically select optimal filter bands for data from non-reporting stations. Results are shown for a set of low SNR events as well as 379 regional and teleseismic events recorded at stations ABKT, KIV, and ANTO in the Middle East.

Leach, Richard R.; Dowla, Farid U.; Schultz, Craig A.

1999-06-01

119

Optimal design of Biquad Switched-Capacitor Active Filters  

E-print Network

? ncasas ? nsn's + nsnsar ? &tla2& and D(=) = ='(1 + ae) + =(asn as s ) 9 ( + as) 16 H(Z) f'0 N('TH 1&0TI0 N AND 00EFFIC'IENT MATCHING T&i &l&sig&i a S(' ?&' tive filter. the =-domain (digital domain) transfer function H(=) which?n&eets the d.... For M&&d& s 2-4: S&ui&e as (4-&d) &xcept that hs(P?) hss three more equations, that is, each op'11&n&sation &s p&'i'for&lied with DMC' ? DAf C:*=-0, or S~?? S~, *=O, or j, /fr = ( f, /fr )* where * denot& s an assumed valne. But in each case a...

Jo, Han Cheol

2012-06-07

120

A three-step test of phosphate sorption efficiency of potential agricultural drainage filter materials.  

PubMed

Phosphorus (P) eutrophication of lakes and streams, coming from drained farmlands, is a serious problem in areas with intensive agriculture. Installation of P sorbing filters at drain outlets may be a solution. Efficient sorbents to be used for such filters must possess high P bonding affinity to retain ortho-phosphate (Pi) at low concentrations. In addition high P sorption capacity, fast bonding and low desorption is necessary. In this study five potential filter materials (Filtralite-P(®), limestone, calcinated diatomaceous earth, shell-sand and iron-oxide based CFH) in four particle size intervals were investigated under field relevant P concentrations (0-161 ?M) and retentions times of 0-24 min. Of the five materials examined, the results from P sorption and desorption studies clearly demonstrate that the iron based CFH is superior as a filter material compared to calcium based materials when tested against criteria for sorption affinity, capacity and stability. The finest CFH and Filtralite-P(®) fractions (0.05-0.5 mm) were best with P retention of ?90% of Pi from an initial concentration of 161 ?M corresponding to 14.5 mmol/kg sorbed within 24 min. They were further capable to retain ?90% of Pi from an initially 16 ?M solution within 1½ min. However, only the finest CFH fraction was also able to retain ?90% of Pi sorbed from the 16 ?M solution against 4 times desorption sequences with 6 mM KNO3. Among the materials investigated, the finest CFH fraction is therefore the only suitable filter material, when very fast and strong bonding of high Pi concentrations is needed, e.g. in drains under P rich soils during extreme weather conditions. PMID:24275107

Lyngsie, G; Borggaard, O K; Hansen, H C B

2014-03-15

121

Optimal filtering of complex turbulent systems with memory depth through consistency constraints  

NASA Astrophysics Data System (ADS)

In this article, we develop a linear theory for optimal filtering of complex turbulent signals with model errors through linear autoregressive models. We will show that when the autoregressive model parameters are chosen such that they satisfy absolute stability and consistency conditions of at least order-2 of the classical multistep method for solving initial value problems, the filtered solutions with autoregressive models of order p?2 are optimal in the sense that they are comparable to the estimates obtained from the true filter with perfect model. This result is reminiscent of the Lax-equivalence fundamental theorem in the analysis of finite difference discretization scheme for the numerical solutions of partial differential equations. We will apply this linear theory to filter two nonlinear problems, the slowest mode of the truncated Burgers-Hopf and the Lorenz-96 model. On these nonlinear problems, we will show that whenever these linear conditions are satisfied, the filtered solutions accuracy is significantly improved. Finally, we will also apply the recently developed offline test criteria to understand the robustness of the multistep filter on various turbulent nature, including the stochastically forced linear advection-diffusion equation and a toy model for barotropic turbulent Rossby waves.

Bakunova, Eugenia S.; Harlim, John

2013-03-01

122

Nonlinear optimal filter technique for analyzing energy depositions in TES sensors driven into saturation  

NASA Astrophysics Data System (ADS)

We present a detailed thermal and electrical model of superconducting transition edge sensors (TESs) connected to quasiparticle (qp) traps, such as the W TESs connected to Al qp traps used for CDMS (Cryogenic Dark Matter Search) Ge and Si detectors. We show that this improved model, together with a straightforward time-domain optimal filter, can be used to analyze pulses well into the nonlinear saturation region and reconstruct absorbed energies with optimal energy resolution.

Shank, B.; Yen, J. J.; Cabrera, B.; Kreikebaum, J. M.; Moffatt, R.; Redl, P.; Young, B. A.; Brink, P. L.; Cherry, M.; Tomada, A.

2014-11-01

123

IEEE TRANSACTIONS ON SIGN-L PROCESSING, VOL. 43, NO. 3, MARCH 1995 59I Optimal Weighted Median Filtering  

E-print Network

attenuation and some structural constraints on the filter's behavior. In certain special cases, the optimal the same advantages as- the median filter: edge preservation and efficient suppression of impulsive noise filters under the MSE and the MAE criteria, [5], [12], [20], [21]. These algorithms were motivated

Gabbouj, Moncef

124

Insights into HER2 signaling from step-by-step optimization of anti-HER2 antibodies.  

PubMed

HER2, a ligand-free tyrosine kinase receptor of the HER family, is frequently overexpressed in breast cancer. The anti-HER2 antibody trastuzumab has shown significant clinical benefits in metastatic breast cancer; however, resistance to trastuzumab is common. The development of monoclonal antibodies that have complementary mechanisms of action results in a more comprehensive blockade of ErbB2 signaling, especially HER2/HER3 signaling. Use of such antibodies may have clinical benefits if these antibodies can become widely accepted. Here, we describe a novel anti-HER2 antibody, hHERmAb-F0178C1, which was isolated from a screen of a phage display library. A step-by-step optimization method was employed to maximize the inhibitory effect of this anti-HER2 antibody. Crystallographic analysis was used to determine the three-dimensional structure to 3.5 Å resolution, confirming that the epitope of this antibody is in domain III of HER2. Moreover, this novel anti-HER2 antibody exhibits superior efficacy in blocking HER2/HER3 heterodimerization and signaling, and its use in combination with pertuzumab has a synergistic effect. Characterization of this antibody revealed the important role of a ligand binding site within domain III of HER2. The results of this study clearly indicate the unique potential of hHERmAb-F0178C1, and its complementary inhibition effect on HER2/HER3 signaling warrants its consideration as a promising clinical treatment. PMID:24838231

Fu, Wenyan; Wang, Yuxiao; Zhang, Yunshan; Xiong, Lijuan; Takeda, Hiroaki; Ding, Li; Xu, Qunfang; He, Lidong; Tan, Wenlong; Bethune, Augus N; Zhou, Lijun

2014-01-01

125

HIGH-LEVEL MULTI-STEP INVERTER OPTIMIZATION, USING A MINIMUM NUMBER OF POWER TRANSISTORS.  

E-print Network

HIGH-LEVEL MULTI-STEP INVERTER OPTIMIZATION, USING A MINIMUM NUMBER OF POWER TRANSISTORS. Juan supplies and semiconductors (transistors or GTOs) for a given number of levels. Different combinations levels of voltage with only four power supplies and sixteen transistors per phase are shown. #12;2 I

Catholic University of Chile (Universidad Católica de Chile)

126

A Comparison of Staggered-Grid, Conventional One-step, and Optimally Accurate Finite-Difference  

E-print Network

A Comparison of Staggered-Grid, Conventional One-step, and Optimally Accurate Finite-Difference Schemes for Computing Synthetic Seismograms Robert J. Geller Department of Earth and Planetary Science: nhirabayashi@slb.com and Department of Earth and Planetary Science, Graduate School of Science, University

Geller, Robert

127

Energy-Based Optimal Step Planning for Weiwei Huang, Junggon Kim and Christopher G. Atkeson  

E-print Network

gait pattern [1]. Studies suggest that minimizing energy consumption is an important factor in human are inspired by literature on human walking energy analysis, and the function parameters are tuned to match cost are combined to obtain an optimal step planning sequence using A* search. I. INTRODUCTION Humans

Treuille, Adrien

128

Nonlinear Motion Cueing Algorithm: Filtering at Pilot Station and Development of the Nonlinear Optimal Filters for Pitch and Roll  

NASA Technical Reports Server (NTRS)

Telban and Cardullo have developed and successfully implemented the non-linear optimal motion cueing algorithm at the Visual Motion Simulator (VMS) at the NASA Langley Research Center in 2005. The latest version of the non-linear algorithm performed filtering of motion cues in all degrees-of-freedom except for pitch and roll. This manuscript describes the development and implementation of the non-linear optimal motion cueing algorithm for the pitch and roll degrees of freedom. Presented results indicate improved cues in the specified channels as compared to the original design. To further advance motion cueing in general, this manuscript describes modifications to the existing algorithm, which allow for filtering at the location of the pilot's head as opposed to the centroid of the motion platform. The rational for such modification to the cueing algorithms is that the location of the pilot's vestibular system must be taken into account as opposed to the off-set of the centroid of the cockpit relative to the center of rotation alone. Results provided in this report suggest improved performance of the motion cueing algorithm.

Zaychik, Kirill B.; Cardullo, Frank M.

2012-01-01

129

Optimization of high speed pipelining in FPGA-based FIR filter design using genetic algorithm  

NASA Astrophysics Data System (ADS)

This paper compares FPGA-based full pipelined multiplierless FIR filter design options. Comparison of Distributed Arithmetic (DA), Common Sub-Expression (CSE) sharing and n-dimensional Reduced Adder Graph (RAG-n) multiplierless filter design methods in term of size, speed, and A*T product are provided. Since DA designs are table-based and CSE/RAG-n designs are adder-based, FPGA synthesis design data are used for a realistic comparison. Superior results of a genetic algorithm based optimization of pipeline registers and non-output fundamental coefficients are shown. FIR filters (posted as open source by Kastner et al.) for filters in the length from 6 to 151 coefficients are used.

Meyer-Baese, Uwe; Botella, Guillermo; Romero, David E. T.; Kumm, Martin

2012-06-01

130

DMT Bit Rate Maximization With Optimal Time Domain Equalizer Filter Bank Architecture  

E-print Network

DMT Bit Rate Maximization With Optimal Time Domain Equalizer Filter Bank Architecture Milos-tone (DMT) is a multicarrier modula- tion method in which the available bandwidth of a com- munication create nearly orthogonal subchannels. DMT has been standardized in [1, 2, 3, 4]. A similar multi- carrier

Evans, Brian L.

131

Performance Optimization of a Photovoltaic Generator with an Active Power Filter Application  

E-print Network

1 Performance Optimization of a Photovoltaic Generator with an Active Power Filter Application (MPPT) for photovoltaic (PV) systems maximizes the power that can be transferred from the PV system), a constant voltage on the DC side of the inverter was proposed, it is a photovoltaic generator which is used

Paris-Sud XI, Université de

132

Optimal steering vector adaptation for linear filters leading to robust beamforming  

E-print Network

. However, the actual steering vector might represent a target which is moving in space, as for exampleOptimal steering vector adaptation for linear filters leading to robust beamforming Michal Natora steering vector is not know, and thus, robust beamforming methods have to be used. In this contribution

Wichmann, Felix

133

Sixth-moment method for multi-channel Bragg filter optimization  

NASA Astrophysics Data System (ADS)

A new method for the crest factor minimization of for multi-tone signal based on the sampling functional is proposed. The minimum of sixth moment is used as an initial value for the minimax search. For high number of tones the optimal values are better than previously reported. Application for fiber Bragg multi-channel filters for telecommunications is discussed.

Belai, Oleg V.; Nemykin, Anton V.; Shapiro, David A.

2011-03-01

134

Sixth-moment method for multi-channel Bragg filter optimization  

NASA Astrophysics Data System (ADS)

A new method for the crest factor minimization of for multi-tone signal based on the sampling functional is proposed. The minimum of sixth moment is used as an initial value for the minimax search. For high number of tones the optimal values are better than previously reported. Application for fiber Bragg multi-channel filters for telecommunications is discussed.

Belai, Oleg V.; Nemykin, Anton V.; Shapiro, David A.

2010-07-01

135

Optimal Characteristic of Optical Filter for White-Light Interferometry based on  

E-print Network

Optimal Characteristic of Optical Filter for White-Light Interferometry based on Sampling Theory. hidemitsu-ogawa@kuramae.ne.jp, a-hira@yamaguchi-u.ac.jp Abstract: White-light interferometry is a technique White-light interferometry is a technique of profiling sur- face topography of objects

Boyer, Edmond

136

Abstract--A new technique for designing EMG spatial filters with optimized spatial selectivity is described. Simulations  

E-print Network

. Additionally, the surface EMG signal is distorted compared to indwelling EMG [11]. Spatial filtering has been-adapted to non-invasive surface EMG. Farina and Rainoldi [8] created an optimal spatial Supported in partAbstract--A new technique for designing EMG spatial filters with optimized spatial selectivity

Clancy, Ted

137

Role of step size and max dwell time in anatomy based inverse optimization for prostate implants  

PubMed Central

In high dose rate (HDR) brachytherapy, the source dwell times and dwell positions are vital parameters in achieving a desirable implant dose distribution. Inverse treatment planning requires an optimal choice of these parameters to achieve the desired target coverage with the lowest achievable dose to the organs at risk (OAR). This study was designed to evaluate the optimum source step size and maximum source dwell time for prostate brachytherapy implants using an Ir-192 source. In total, one hundred inverse treatment plans were generated for the four patients included in this study. Twenty-five treatment plans were created for each patient by varying the step size and maximum source dwell time during anatomy-based, inverse-planned optimization. Other relevant treatment planning parameters were kept constant, including the dose constraints and source dwell positions. Each plan was evaluated for target coverage, urethral and rectal dose sparing, treatment time, relative target dose homogeneity, and nonuniformity ratio. The plans with 0.5 cm step size were seen to have clinically acceptable tumor coverage, minimal normal structure doses, and minimum treatment time as compared with the other step sizes. The target coverage for this step size is 87% of the prescription dose, while the urethral and maximum rectal doses were 107.3 and 68.7%, respectively. No appreciable difference in plan quality was observed with variation in maximum source dwell time. The step size plays a significant role in plan optimization for prostate implants. Our study supports use of a 0.5 cm step size for prostate implants. PMID:24049323

Manikandan, Arjunan; Sarkar, Biplab; Rajendran, Vivek Thirupathur; King, Paul R.; Sresty, N.V. Madhusudhana; Holla, Ragavendra; Kotur, Sachin; Nadendla, Sujatha

2013-01-01

138

Preparation and optimization of the laser thin film filter  

NASA Astrophysics Data System (ADS)

A co-colored thin film device for laser-induced damage threshold test system is presented in this paper, to make the laser-induced damage threshold tester operating at 532nm and 1064nm band. Through TFC simulation software, a film system of high-reflection, high -transmittance, resistance to laser damage membrane is designed and optimized. Using thermal evaporation technique to plate film, the optical properties of the coating and performance of the laser-induced damage are tested, and the reflectance and transmittance and damage threshold are measured. The results show that, the measured parameters, the reflectance R >= 98%@532nm, the transmittance T >= 98%@1064nm, the laser-induced damage threshold LIDT >= 4.5J/cm2 , meet the design requirements, which lays the foundation of achieving laser-induced damage threshold multifunction tester.

Su, Jun-hong; Wang, Wei; Xu, Jun-qi; Cheng, Yao-jin; Wang, Tao

2014-08-01

139

Optimal nonlinear filtering for track-before-detect in IR image sequences  

NASA Astrophysics Data System (ADS)

The 3D matched filter proposed by Reed et al. and its generalizations provide a powerful processing technique for detecting moving low observable targets. This technique is a centerpiece of various track-before-detect (TBD) systems. However, the 3D matched filter was designed for constant velocity targets and its applicability to more complicated patterns of target dynamics is not obvious. In this paper the 3D matched filter and BAVF are extended to the case of switching multiple models of target dynamics. We demonstrate that the 3D matched filtering can be cast into a general framework of optimal spatio-temporal nonlinear filtering for hidden Markov models. A robust and computationally efficient Bayesian algorithm for detection and tracking of low observable agile targets in IR Search and Track (IRST) systems is presented. The proposed algorithm is fully sequential. It facilitates optimal fusion of sensor measurements and prior information regarding possible threats. The algorithm is implemented as a TBD subsystem for IRST, however the general methodology is equally applicable for other imaging sensors.

Rozovskii, Boris L.; Petrov, Anton

1999-10-01

140

Linear variable filter optimization for emergency response chemical detection and discrimination  

NASA Astrophysics Data System (ADS)

Linear variable filter design and fabrication for LWIR is now commercially available for use in the development of remote sensing systems. The linear variable filter is attached directly to the cold shield of the focal plane array. The resulting compact spectrometer assemblies are completely contained in the Dewar system. This approach eliminates many of the wavelength calibration problems associated with current prism and grating systems and also facilitates the cost effective design and fabrication of aerial sensing systems for specific applications. This paper describes a study that was conducted with the following three objectives: 1) Determine if a multi-channel linear-variable-filter-based line scanner system can be used to discriminate a set of chemical vapors that represent a high probability of occurrence during a typical emergency response chemical incident; 2) Determine which multi-channel linear variable filter design is optimal; and 3) Determine the acceptable instrument noise equivalent spectral radiance for this application. A companion paper describes a separate study that was conducted to determine the concentration levels at which detection and discrimination can be achieved for the various chemicals based on the optimal filter design under various degrees of imperfect atmospheric correction.

Shen, Sylvia S.; Lewis, Paul E.

2010-08-01

141

Design Optimization of Vena Cava Filters: An application to dual filtration devices  

SciTech Connect

Pulmonary embolism (PE) is a significant medical problem that results in over 300,000 fatalities per year. A common preventative treatment for PE is the insertion of a metallic filter into the inferior vena cava that traps thrombi before they reach the lungs. The goal of this work is to use methods of mathematical modeling and design optimization to determine the configuration of trapped thrombi that minimizes the hemodynamic disruption. The resulting configuration has implications for constructing an optimally designed vena cava filter. Computational fluid dynamics is coupled with a nonlinear optimization algorithm to determine the optimal configuration of trapped model thrombus in the inferior vena cava. The location and shape of the thrombus are parameterized, and an objective function, based on wall shear stresses, determines the worthiness of a given configuration. The methods are fully automated and demonstrate the capabilities of a design optimization framework that is broadly applicable. Changes to thrombus location and shape alter the velocity contours and wall shear stress profiles significantly. For vena cava filters that trap two thrombi simultaneously, the undesirable flow dynamics past one thrombus can be mitigated by leveraging the flow past the other thrombus. Streamlining the shape of thrombus trapped along the cava wall reduces the disruption to the flow, but increases the area exposed to abnormal wall shear stress. Computer-based design optimization is a useful tool for developing vena cava filters. Characterizing and parameterizing the design requirements and constraints is essential for constructing devices that address clinical complications. In addition, formulating a well-defined objective function that quantifies clinical risks and benefits is needed for designing devices that are clinically viable.

Singer, M A; Wang, S L; Diachin, D P

2009-12-03

142

Global localization of 3D anatomical structures by pre-filtered Hough Forests and discrete optimization  

PubMed Central

The accurate localization of anatomical landmarks is a challenging task, often solved by domain specific approaches. We propose a method for the automatic localization of landmarks in complex, repetitive anatomical structures. The key idea is to combine three steps: (1) a classifier for pre-filtering anatomical landmark positions that (2) are refined through a Hough regression model, together with (3) a parts-based model of the global landmark topology to select the final landmark positions. During training landmarks are annotated in a set of example volumes. A classifier learns local landmark appearance, and Hough regressors are trained to aggregate neighborhood information to a precise landmark coordinate position. A non-parametric geometric model encodes the spatial relationships between the landmarks and derives a topology which connects mutually predictive landmarks. During the global search we classify all voxels in the query volume, and perform regression-based agglomeration of landmark probabilities to highly accurate and specific candidate points at potential landmark locations. We encode the candidates’ weights together with the conformity of the connecting edges to the learnt geometric model in a Markov Random Field (MRF). By solving the corresponding discrete optimization problem, the most probable location for each model landmark is found in the query volume. We show that this approach is able to consistently localize the model landmarks despite the complex and repetitive character of the anatomical structures on three challenging data sets (hand radiographs, hand CTs, and whole body CTs), with a median localization error of 0.80 mm, 1.19 mm and 2.71 mm, respectively. PMID:23664450

Donner, René; Menze, Bjoern H.; Bischof, Horst; Langs, Georg

2013-01-01

143

Optimized piezoelectric energy harvesting circuit using step-down converter in discontinuous conduction mode  

Microsoft Academic Search

An optimized method of harvesting vibrational energy with a piezoelectric element using a step-down DC-DC converter is presented. In this configuration, the converter regulates the power flow from the piezoelectric element to the desired electronic load. Analysis of the converter in discontinuous current conduction mode results in an expression for the duty cycle-power relationship. Using parameters of the mechanical system,

Geffrey K. Ottman; Heath F. Hofmann; George A. Lesieutre

2003-01-01

144

One-step optimal control of a continuous solution polymerization reactor  

Microsoft Academic Search

This paper describes the application of minimum variance and one-step optimal controllers to the control of conversion in a solution polymerization reactor. The objective is the servo control of polymer conversion. A new saturation and controller windup algorithm proposed in Ogunye (1994) was implemented for the set-point tracking control policies. The improvement in closed-loop performance using this saturation algorithm over

Ayode B. Ogunye; A. Penlidis

1995-01-01

145

Optimization of ecosystem model parameters with different temporal variabilities using tower flux data and an ensemble Kalman filter  

NASA Astrophysics Data System (ADS)

Terrestrial ecosystem models have been widely used to simulate carbon, water and energy fluxes and climate-ecosystem interactions. In these models, some vegetation and soil parameters are determined based on limited studies from literatures without consideration of their seasonal variations. Data assimilation (DA) provides an effective way to optimize these parameters at different time scales . In this study, an ensemble Kalman filter (EnKF) is developed and applied to optimize two key parameters of an ecosystem model, namely the Boreal Ecosystem Productivity Simulator (BEPS): (1) the maximum photosynthetic carboxylation rate (Vcmax) at 25 °C, and (2) the soil water stress factor (fw) for stomatal conductance formulation. These parameters are optimized through assimilating observations of gross primary productivity (GPP) and latent heat (LE) fluxes measured in a 74 year-old pine forest, which is part of the Turkey Point Flux Station's age-sequence sites. Vcmax is related to leaf nitrogen concentration and varies slowly over the season and from year to year. In contrast, fw varies rapidly in response to soil moisture dynamics in the root-zone. Earlier studies suggested that DA of vegetation parameters at daily time steps leads to Vcmax values that are unrealistic. To overcome the problem, we developed a three-step scheme to optimize Vcmax and fw. First, the EnKF is applied daily to obtain precursor estimates of Vcmax and fw. Then Vcmax is optimized at different time scales assuming fw is unchanged from first step. The best temporal period or window size is then determined by analyzing the magnitude of the minimized cost-function, and the coefficient of determination (R2) and Root-mean-square deviation (RMSE) of GPP and LE between simulation and observation. Finally, the daily fw value is optimized for rain free days corresponding to the Vcmax curve from the best window size. The optimized fw is then used to model its relationship with soil moisture. We found that the optimized fw is best correlated linearly to soil water content at 5 to 10 cm depth. We also found that both the temporal scale or window size and the priori uncertainty of Vcmax (given as its standard deviation) are important in determining the seasonal trajectory of Vcmax. During the leaf expansion stage, an appropriate window size leads to reasonable estimate of Vcmax. In the summer, the fluctuation of optimized Vcmax is mainly caused by the uncertainties in Vcmax but not the window size. Our study suggests that a smooth Vcmax curve optimized from an optimal time window size is close to the reality though the RMSE of GPP at this window is not the minimum. It also suggests that for the accurate optimization of Vcmax, it is necessary to set appropriate levels of uncertainty of Vcmax in the spring and summer because the rate of leaf nitrogen concentration change is different over the season. Parameter optimizations for more sites and multi-years are in progress.

He, L.; Chen, J. M.; Liu, J.; Mo, G.; Zhen, T.; Chen, B.; Wang, R.; Arain, M.

2013-12-01

146

Design Optimization of Passively Mode-Locked Semiconductor Lasers With Intracavity Grating Spectral Filters  

NASA Astrophysics Data System (ADS)

We consider design optimization of passively mode-locked two-section semiconductor lasers that incorporate intracavity grating spectral filters. Our goal is to develop a method for finding the optimal wavelength location for the filter in order to maximize the region of stable mode-locking as a function of drive current and reverse bias in the absorber section. In order to account for material dispersion in the two sections of the laser, we use analytic approximations for the gain and absorption as a function of carrier density and frequency. Fits to measured gain and absorption curves then provide inputs for numerical simulations based on a large signal accurate delay-differential model of the mode-locked laser. We show how a unique set of model parameters for each value of the drive current and reverse bias voltage can be selected based on the variation of the net gain along branches of steady-state solutions of the model. We demonstrate the validity of this approach by demonstrating qualitative agreement between numerical simulations and the measured current-voltage phase-space of a two-section Fabry-Perot laser. We then show how to adapt this method to determine an optimum location for the spectral filter in a notional device with the same material composition, based on the targeted locking range, and accounting for the modal selectivity of the filter.

O'Callaghan, Finbarr; Bitauld, David; O'Brien, Stephen

2014-11-01

147

Multi-Bandwidth Frequency Selective Surfaces for Near Infrared Filtering: Design and Optimization  

NASA Technical Reports Server (NTRS)

Frequency selective surfaces are widely used in the microwave and millimeter wave regions of the spectrum for filtering signals. They are used in telecommunication systems for multi-frequency operation or in instrument detectors for spectroscopy. The frequency selective surface operation depends on a periodic array of elements resonating at prescribed wavelengths producing a filter response. The size of the elements is on the order of half the electrical wavelength, and the array period is typically less than a wavelength for efficient operation. When operating in the optical region, diffraction gratings are used for filtering. In this regime the period of the grating may be several wavelengths producing multiple orders of light in reflection or transmission. In regions between these bands (specifically in the infrared band) frequency selective filters consisting of patterned metal layers fabricated using electron beam lithography are beginning to be developed. The operation is completely analogous to surfaces made in the microwave and millimeter wave region except for the choice of materials used and the fabrication process. In addition, the lithography process allows an arbitrary distribution of patterns corresponding to resonances at various wavelengths to be produced. The design of sub-millimeter filters follows the design methods used in the microwave region. Exacting modal matching, integral equation or finite element methods can be used for design. A major difference though is the introduction of material parameters and thicknesses tha_ may not be important in longer wavelength designs. This paper describes the design of multi-bandwidth filters operating in the I-5 micrometer wavelength range. This work follows on previous design [1,2]. In this paper extensions based on further optimization and an examination of the specific shape of the element in the periodic cell will be reported. Results from the design, manufacture and test of linear wedge filters built using micro-lithographic techniques and used ir spectral imaging applications will be presented.

Cwik, Tom; Fernandez, Salvador; Ksendzov, A.; LaBaw, Clayton C.; Maker, Paul D.; Muller, Richard E.

1999-01-01

148

Multi-Bandwidth Frequency Selective Surfaces for Near Infrared Filtering: Design and Optimization  

NASA Technical Reports Server (NTRS)

Frequency selective surfaces are widely used in the microwave and millimeter wave regions of the spectrum for filtering signals. They are used in telecommunication systems for multi-frequency operation or in instrument detectors for spectroscopy. The frequency selective surface operation depends on a periodic array of elements resonating at prescribed wavelengths producing a filter response. The size of the elements is on the order of half the electrical wavelength, and the array period is typically less than a wavelength for efficient operation. When operating in the optical region, diffraction gratings are used for filtering. In this regime the period of the grating may be several wavelengths producing multiple orders of light in reflection or transmission. In regions between these bands (specifically in the infrared band) frequency selective filters consisting of patterned metal layers fabricated using electron beam lithography are beginning to be developed. The operation is completely analogous to surfaces made in the microwave and millimeter wave region except for the choice of materials used and the fabrication process. In addition, the lithography process allows an arbitrary distribution of patterns corresponding to resonances at various wavelengths to be produced. The design of sub-millimeter filters follows the design methods used in the microwave region. Exacting modal matching, integral equation or finite element methods can be used for design. A major difference though is the introduction of material parameters and thicknesses that may not be important in longer wavelength designs. This paper describes the design of multi- bandwidth filters operating in the 1-5 micrometer wavelength range. This work follows on a previous design. In this paper extensions based on further optimization and an examination of the specific shape of the element in the periodic cell will be reported. Results from the design, manufacture and test of linear wedge filters built using microlithographic techniques and used in spectral imaging applications will be presented.

Cwik, Tom; Fernandez, Salvador; Ksendzov, A.; LaBaw, Clayton C.; Maker, Paul D.; Muller, Richard E.

1998-01-01

149

Optimal Long Binary Phase Code-Mismatched Filter Pairs with the Application to Ionospheric Radars  

NASA Astrophysics Data System (ADS)

Binary phase codes have been often used in radar systems. The most widely known binary phase codes are Barker codes. Families of binary phase codes, which are called alternating codes, have been also discovered]. In a radar system, which employs a binary phase code, a matched filter is usually used to obtain a very high range resolution without decreasing the average transmitted power. However, matched filtering of a binary phase code gives unwanted sidelobes at the filter output. The amplitude of the sidelobes depends on the phase patterns of the binary phase code. Significant research effort has gone to search binary phase patterns that give smallest possible sidelobes. Most often peak-to-sidelobe ratio (PSR), integrated sidelobe ratio (TSR) and merit factor (F) are used as criterions to search for the best binary phase codes. The Barker codes have relatively high PSR. Other kind of binary phases with improved PSR have been found, including the 28-element code by Turyn] and the 40-element code by Lindner]. Although binary phase codes with maximum PSR can be satisfactory for some applications, in some cases removing the sidelobes reveals new and important information. Key showed that weighting networks to be placed after the standard matched filter can be designed, which reduces the sidelobes to an arbitrary low level. For any periodic digital signal with linearly independent cyclical shifts, lpatov] has showed that a filter can be constructed that suppresses to a zero level all the sidelobes. However, the filter has associated SNR losses when compared to the corresponding matched filter. Lpatov carried out a computer search for a binary periodic signal-filter pair with minimum possible SNR losses. The search includes all binary codes of length up to 30 elements. A different approach for eliminating the sidelobes in periodical binary phase codes by using mismatched filter have been published by Rohling and Plagg]. Exhaustive search for optimal aperiodic binary phase codes and mismatched filter pairs up to length of 25 has been carried out by Lehtinen. The benefits of eliminating sidelobes are also demonstrated in using real radar measurements. In this paper we present mismatched filtering of aperiodic binary phase codes. This is done without creating any sidelobes. A mismatched filter has small losses in SNR when compared with the corresponding matched filter. We have selected the best binary phase codes with length from 26 to 39. The best codes are the ones which have the smallest SNR losses in mismatched filtering when compared with the corresponding matched filtering. We have chosen one best code from each length and this means we have selected 14 different length best binary phase codes. These codes were chosen from a total number of 5.4972 x 1011 investigated codes. We have found these codes have nearly similar losses in SNR and it is about 15 percent. We did not find a binary phase code that outperforms the well-known 13-element Barker code, which has 4.8 percent SYR losses .

Damtie, B.; Lehtinen, M.; Orispaã, M.; Vierinen, J.

2006-11-01

150

Stepped Care to Optimize Pain care Effectiveness (SCOPE) trial study design and sample characteristics.  

PubMed

Pain is the most common physical symptom in primary care, accounting for an enormous burden in terms of patient suffering, quality of life, work and social disability, and health care and societal costs. Although collaborative care interventions are well-established for conditions such as depression, fewer systems-based interventions have been tested for chronic pain. This paper describes the study design and baseline characteristics of the enrolled sample for the Stepped Care to Optimize Pain care Effectiveness (SCOPE) study, a randomized clinical effectiveness trial conducted in five primary care clinics. SCOPE has enrolled 250 primary care veterans with persistent (3 months or longer) musculoskeletal pain of moderate severity and randomized them to either the stepped care intervention or usual care control group. Using a telemedicine collaborative care approach, the intervention couples automated symptom monitoring with a telephone-based, nurse care manager/physician pain specialist team to treat pain. The goal is to optimize analgesic management using a stepped care approach to drug selection, symptom monitoring, dose adjustment, and switching or adding medications. All subjects undergo comprehensive outcome assessments at baseline, 1, 3, 6 and 12 months by interviewers blinded to treatment group. The primary outcome is pain severity/disability, and secondary outcomes include pain beliefs and behaviors, psychological functioning, health-related quality of life and treatment satisfaction. Innovations of SCOPE include optimized analgesic management (including a stepped care approach, opioid risk stratification, and criteria-based medication adjustment), automated monitoring, and centralized care management that can cover multiple primary care practices. PMID:23228858

Kroenke, Kurt; Krebs, Erin; Wu, Jingwei; Bair, Matthew J; Damush, Teresa; Chumbler, Neale; York, Tish; Weitlauf, Sharon; McCalley, Stephanie; Evans, Erica; Barnd, Jeffrey; Yu, Zhangsheng

2013-03-01

151

Implicit application of polynomial filters in a k-step Arnoldi method  

NASA Technical Reports Server (NTRS)

The Arnoldi process is a well known technique for approximating a few eigenvalues and corresponding eigenvectors of a general square matrix. Numerical difficulties such as loss of orthogonality and assessment of the numerical quality of the approximations as well as a potential for unbounded growth in storage have limited the applicability of the method. These issues are addressed by fixing the number of steps in the Arnoldi process at a prescribed value k and then treating the residual vector as a function of the initial Arnoldi vector. This starting vector is then updated through an iterative scheme that is designed to force convergence of the residual to zero. The iterative scheme is shown to be a truncation of the standard implicitly shifted QR-iteration for dense problems and it avoids the need to explicitly restart the Arnoldi sequence. The main emphasis of this paper is on the derivation and analysis of this scheme. However, there are obvious ways to exploit parallelism through the matrix-vector operations that comprise the majority of the work in the algorithm. Preliminary computational results are given for a few problems on some parallel and vector computers.

Sorensen, D. C.

1990-01-01

152

An Optimized Blockwise Non Local Means Denoising Filter for 3D Magnetic Resonance Images  

Microsoft Academic Search

ó A critical issue in image restoration is the problem of noise removal while keeping the integrity of relevant image information. Denoising is a crucial step to increase image quality and to improve the performance of all the tasks needed for quantitative imaging analysis. The method proposed in this paper is based on a 3D optimized blockwise version of the

Pierrick Coupe; Pierre Yger; Sylvain Prima; Pierre Hellier; Charles Kervrann; Christian Barillot

2008-01-01

153

A Two-Step Double Filter Method to Extract Open Water Surfaces from Landsat ETM+ Imagery  

NASA Astrophysics Data System (ADS)

In arid and semi-arid areas, lakes and temporal ponds play a significant role in agriculture and livelihood of local communities as well as in ecology. Monitoring the changes of these open water bodies allows to draw conclusions on water use as well as climatic impacts and can assist in the formulation of a sustainable resource management strategy. The simultaneous monitoring of larger numbers of water bodies with respect to their stage and area is feasible with the aid of remote sensing. Here the monitoring of lake surface areas is discussed. Landsat TM and ETM+ images provide a medium resolution of 30m, and offer an easily available data source to monitor the long term changes of water surfaces in arid and semi-arid regions. In the past great effort was put into developing simple indices to extract water surfaces from satellite images. However, there is a common problem in achieving accurate results with these indices: How to select a threshold value for water pixels without introducing excessive subjective judgment. The threshold value would also have to vary with location, land features and seasons, allowing for inherent uncertainty. A new method was developed using Landsat ETM+ imaginary (30 meter resolution) to extract open water surfaces. This method uses the Normalized Difference of Vegetation Index (NDVI) as the basis for an objective way of selecting threshold values of Modified Normalized Difference of Water Index (MNDWI) and Stress Degree Days (SDD), which were used as a combined filter to extract open water surfaces. We choose two study areas to verify the method. One study area is in Northeast China, where bigger lakes, smaller muddy ponds and wetlands are interspersed with agricultural land and salt crusts. The other one is Kafue Flats in Zambia, where seasonal floods of the Zambezi River create seasonal wetlands in addition to the more permanent water ponds and river channels. For both sites digital globe images of 0.5 meter resolution are available, which were taken within a few days of Landsat passing dates and which will serve here as ground truth information. On their basis the new method was compared to other available methods for extracting water pixels. Compared to the other methods, the new method can extract water surface not only from deep lakes/reservoirs and wetlands but also from small mud ponds in alkali flats and irrigation ponds in the fields. For the big and deep lakes, the extracted boundary of the lakes fits accurately the observed boundary. Five test sites in the study area in Northeast China with only shallow water surfaces were chosen and tested. The extracted water surfaces were compared with each site's digital globe maps, respectively to determine the accuracy of the method. The comparison shows that the method could extract all completely wet pixels (water area covering 100% of the pixel area) in all test sites. For partially wet pixels (50-100% of pixel area), the model can detect 91% of all pixels. No dry pixels were mistaken by the model as water pixels. Keywords: Remote sensing, Landsat ETM+ imaginary, Water Surface, NDVI, MNDWI, and SDD

Wang, Haijing; Kinzelbach, Wolfgang

2010-05-01

154

Optimizing performance of ceramic pot filters in Northern Ghana and modeling flow through paraboloid-shaped filters/  

E-print Network

This work aimed to inform the design of ceramic pot filters to be manufactured by the organization Pure Home Water (PHW) in Northern Ghana, and to model the flow through an innovative paraboloid-shaped ceramic pot filter. ...

Miller, Travis Reed

2010-01-01

155

Miniaturized Bandpass Filter Using a Meandered Stepped-Impedance Resonator with a Meandered-Line Stub-Load on a GaAs Substrate  

PubMed Central

This paper reports a compact bandpass filter with improved skirt selectivity using integrated passive device fabrication technology on a GaAs substrate. The structure of the filter consists of electromagnetically coupled meandered-line symmetric stepped-impedance resonators. The strength of the coupling between the resonators is enhanced by using a meandered-line stub-load inside the resonators to improve the selectivity and miniaturize the size of the filter. In addition, the center frequency of the filter can be flexibly controlled by varying degrees of the capacitive coupling between resonator and stub-load. To verify the proposed concept, a protocol bandpass filter with center frequency of 6.53?GHz was designed, fabricated, and measured, with a return loss and insertion loss of 39.1?dB and 1.63?dB. PMID:25386617

Chuluunbaatar, Z.; Wang, C.; Kim, N. Y.

2014-01-01

156

Miniaturized Bandpass Filter Using a Meandered Stepped-Impedance Resonator with a Meandered-Line Stub-Load on a GaAs Substrate.  

PubMed

This paper reports a compact bandpass filter with improved skirt selectivity using integrated passive device fabrication technology on a GaAs substrate. The structure of the filter consists of electromagnetically coupled meandered-line symmetric stepped-impedance resonators. The strength of the coupling between the resonators is enhanced by using a meandered-line stub-load inside the resonators to improve the selectivity and miniaturize the size of the filter. In addition, the center frequency of the filter can be flexibly controlled by varying degrees of the capacitive coupling between resonator and stub-load. To verify the proposed concept, a protocol bandpass filter with center frequency of 6.53?GHz was designed, fabricated, and measured, with a return loss and insertion loss of 39.1?dB and 1.63?dB. PMID:25386617

Chuluunbaatar, Z; Wang, C; Kim, N Y

2014-01-01

157

Optimal noise reduction in 3D reconstructions of single particles using a volume-normalized filter.  

PubMed

The high noise level found in single-particle electron cryo-microscopy (cryo-EM) image data presents a special challenge for three-dimensional (3D) reconstruction of the imaged molecules. The spectral signal-to-noise ratio (SSNR) and related Fourier shell correlation (FSC) functions are commonly used to assess and mitigate the noise-generated error in the reconstruction. Calculation of the SSNR and FSC usually includes the noise in the solvent region surrounding the particle and therefore does not accurately reflect the signal in the particle density itself. Here we show that the SSNR in a reconstructed 3D particle map is linearly proportional to the fractional volume occupied by the particle. Using this relationship, we devise a novel filter (the "single-particle Wiener filter") to minimize the error in a reconstructed particle map, if the particle volume is known. Moreover, we show how to approximate this filter even when the volume of the particle is not known, by optimizing the signal within a representative interior region of the particle. We show that the new filter improves on previously proposed error-reduction schemes, including the conventional Wiener filter as well as figure-of-merit weighting, and quantify the relationship between all of these methods by theoretical analysis as well as numeric evaluation of both simulated and experimentally collected data. The single-particle Wiener filter is applicable across a broad range of existing 3D reconstruction techniques, but is particularly well suited to the Fourier inversion method, leading to an efficient and accurate implementation. PMID:22613568

Sindelar, Charles V; Grigorieff, Nikolaus

2012-10-01

158

Two Step Derivatization for the Analyses of Organic, Amino Acids and Glycines on Filter Paper Plasma by GC-MS\\/SIM  

Microsoft Academic Search

A rapid dried-filter paper plasma-spot analytical method was developed to quantify organic acids, amino acids, and glycines\\u000a simultaneously in a two-step derivatization procedure with good sensitivity and specificity. The new method involves a two-step\\u000a trimethylsilyl (TMS) - trif-luoroacyl (TFA) derivatization procedure using GC-MS\\/ selective ion monitoring (GC-MS\\/SIM). The\\u000a dried-filter paper plasma was fortified with an internal standard (tropate) as well

Hye-Ran Yoon

2007-01-01

159

Towards optimal explicit time-stepping schemes for the gyrokinetic equations  

E-print Network

The nonlinear gyrokinetic equations describe plasma turbulence in laboratory and astrophysical plasmas. To solve these equations, massively parallel codes have been developed and run on present-day supercomputers. This paper describes measures to improve the efficiency of such computations, thereby making them more realistic. Explicit Runge-Kutta schemes are considered to be well suited for time-stepping. Although the numerical algorithms are often highly optimized, performance can still be improved by a suitable choice of the time-stepping scheme, based on spectral analysis of the underlying operator. Here, an operator splitting technique is introduced to combine first-order Runge-Kutta-Chebychev schemes for the collision term with fourth-order schemes for the remaining terms. In the nonlinear regime, based on the observation of eigenvalue shifts due to the (generalized) $E\\times B$ advection term, an accurate and robust estimate for the nonlinear timestep is developed. The presented techniques can reduce si...

Doerk, H

2014-01-01

160

Optimal hydrograph separation filter to evaluate transport routines of hydrological models  

NASA Astrophysics Data System (ADS)

Hydrograph separation (HS) using recursive digital filter approaches focuses on trying to distinguish between the rapidly occurring discharge components like surface runoff, and the slowly changing discharge originating from interflow and groundwater. Filter approaches are mathematical procedures, which perform the HS using a set of separation parameters. The first goal of this study is an attempt to minimize the subjective influence that a user of the filter technique exerts on the results by the choice of such filter parameters. A simple optimal HS (OHS) technique for the estimation of the separation parameters was introduced, relying on measured stream hydrochemistry. The second goal is to use the OHS parameters to develop a benchmark model that can be used as a geochemical model itself, or to test the performance of process based hydro-geochemical models. The benchmark model quantifies the degree of knowledge that the stream flow time series itself contributes to the hydrochemical analysis. Results of the OHS show that the two HS fractions ("rapid" and "slow") differ according to the geochemical substances which were selected. The OHS parameters were then used to demonstrate how to develop benchmark model for hydro-chemical predictions. Finally, predictions of solute transport from a process-based hydrological model were compared to the proposed benchmark model. Our results indicate that the benchmark model illustrated and quantified the contribution of the modeling procedure better than only using traditional measures like r2 or the Nash-Sutcliffe efficiency.

Rimmer, Alon; Hartmann, Andreas

2014-05-01

161

Optimization of a preparative multimodal ion exchange step for purification of a potential malaria vaccine.  

PubMed

In 2000 the implementation of quality by design (QbD) was introduced by the Food and Drug Administration (FDA) and described in the ICH Q8, Q9 and Q10 guidelines. Since that time, systematic optimization strategies for purification of biopharmaceuticals have gained a more important role in industrial process development. In this investigation, the optimization strategy was carried out by adopting design of experiments (DoE) in small scale experiments. A combination method comprising a desalting and a multimodal ion exchange step was used for the experimental runs via the chromatographic system ÄKTA™ avant. The multimodal resin Capto™ adhere was investigated as an alternative to conventional ion exchange and hydrophobic interaction resins for the intermediate purification of the potential malaria vaccine D1M1. The ligands, used in multimodal chromatography, interact with the target molecule in different ways. The multimodal functionality includes the binding of proteins in spite of the ionic strength of the loading material. The target protein binds at specific salt conditions and can be eluted by a step gradient decreasing the pH value and reducing the ionic strength. It is possible to achieve a maximized purity and recovery of the product because degradation products and other contaminants do not bind at specific salt concentrations at which the product still binds to the ligands. PMID:25271026

Paul, Jessica; Jensen, Sonja; Dukart, Arthur; Cornelissen, Gesine

2014-10-31

162

Optimization of the Cathode Catalyst Layer Composition of a PEM Fuel Cell Using a Novel 2-Step Preparation Method  

E-print Network

doesn't allow optimal placement of Nafion® and Teflon® within the catalyst layer leading to coverage of active catalyst sites by Teflon®. By means of a two-step process the formation of the catalyst ink was separated into two parts. In the first step, a...

Friedmann, Roland

2009-03-05

163

First laboratory demonstration of closed-loop Kalman based optimal control for vibration filtering and simplified MCAO  

NASA Astrophysics Data System (ADS)

Classic Adaptive Optics (AO) is now successfully implemented on a growing number of ground-based imaging systems. Nevertheless some limitations are still to cope with. First, the AO standard control laws are unable to easily handle vibrations. In the particular case of eXtreme AO (XAO), which requires a highly efficient AO, these vibrations can thus be much penalizing. We have previously shown that a Kalman based control law can provide both an efficient correction of the turbulence and a strong vibration filtering. Second, anisoplanatism effects lead to a small corrected field of view. Multi-Conjugate AO (MCAO) is a promising concept that should increase significantly this field of view. We have shown numerically that MCAO correction can be highly improved by optimal control based on a Kalman filter. This article presents the first laboratory demonstration of these two concepts. We use a classic AO bench available at Onera with a deformable mirror (DM) in the pupil and a Shack-Hartmann Wave Front Sensor (WFS) pointing at an on-axis guide-star. The turbulence is produced by a rotating phase screen in altitude. First, this AO configuration is used to validate the ability of our control approach to filter out system vibrations and improve the overall performance of the AO closed-loop, compared to classic controllers. The consequences on the RTC design of an XAO system is discussed. Then, we optimize the correction for an off-axis star although the WFS still points at the on-axis star. This Off-Axis AO (OAAO) can be seen as a first step towards MCAO or Multi-Object AO in a simplified configuration. It proves the ability of our control law to estimate the turbulence in altitude and correct in the direction of interest. We describe the off-axis correction tests performed in a dynamic mode (closed-loop) using our Kalman based control. We present the evolution of the off-axis correction according to the angular separation between the stars. A highly significant improvement in performance is demonstrated.

Petit, C.; Conan, J.-M.; Kulcsár, C.; Raynaud, H.-F.; Fusco, T.; Montri, J.; Rabaud, D.

2006-06-01

164

Optimization of drawbead design in sheet forming using one step finite element method coupled with response surface methodology  

Microsoft Academic Search

In a sheet forming process, drawbead plays an important role on the control of the material flow. In this paper, a numerical procedure for the design of forming processes is described. It is based on the coupling of an optimization technique and the simplified one step finite element method (also called inverse approach). The optimization technique allows adjustment of the

Bingtao Tang; Jixian Sun; Zhen Zhao; Jun Chen; Xueyu Ruan

2006-01-01

165

Design optimization of passively mode-locked semiconductor lasers with intracavity grating spectral filters  

E-print Network

We consider design optimization of passively mode-locked two-section semiconductor lasers that incorporate intracavity grating spectral filters. Our goal is to develop a method for finding the optimal wavelength location for the filter in order to maximize the region of stable mode-locking as a function of drive current and reverse bias in the absorber section. In order to account for material dispersion in the two sections of the laser, we use analytic approximations for the gain and absorption as a function of carrier density and frequency. Fits to measured gain and absorption curves then provide inputs for numerical simulations based on a large signal accurate delay-differential model of the mode-locked laser. We show how a unique set of model parameters for each value of the drive current and reverse bias voltage can be selected based on the variation of the net gain along branches of steady-state solutions of the model. We demonstrate the validity of this approach by demonstrating qualitative agreement b...

O'Callaghan, Finbarr; O'Brien, Stephen

2014-01-01

166

Optimal hydrograph separation filter to evaluate transport routines of hydrological models  

NASA Astrophysics Data System (ADS)

Hydrograph separation (HS) using recursive digital filter approaches focuses on trying to distinguish between the rapidly occurring discharge components like surface runoff, and the slowly changing discharge originating from interflow and groundwater. Filter approaches are mathematical procedures, which perform the HS using a set of separation parameters. The first goal of this study is to minimize the subjective influence that a user of the filter technique exerts on the results by the choice of such filter parameters. A simple optimal HS (OHS) technique for the estimation of the separation parameters was introduced, relying on measured stream hydrochemistry. The second goal is to use the OHS parameters to benchmark the performance of process-based hydro-geochemical (HG) models. The new HG routine can be used to quantify the degree of knowledge that the stream flow time series itself contributes to the HG analysis, using newly developed benchmark geochemistry efficiency (BGE). Results of the OHS show that the two HS fractions (“rapid” and “slow”) differ according to the HG substances which were selected. The BFImax parameter (long-term ratio of baseflow to total streamflow) ranged from 0.26 to 0.94 for SO4-2 and total suspended solids, TSS, respectively. Then, predictions of SO4-2 transport from a process-based hydrological model were benchmarked with the proposed HG routine, in order to evaluate the significance of the HG routines in the process-based model. This comparison provides valuable quality test that would not be obvious when using the traditional measures like r2 or the NSE (Nash-Sutcliffe efficiency). The process-based model resulted in r2 = 0.65 and NSE = 0.65, while the benchmark routine results were slightly lower with r2 = 0.61 and NSE = 0.58. However, the comparison between the two model resulted in obvious advantage for the process-based model with BGE = 0.15.

Rimmer, Alon; Hartmann, Andreas

2014-06-01

167

Optimization of a One-Step Heat-Inducible In Vivo Mini DNA Vector Production System  

PubMed Central

While safer than their viral counterparts, conventional circular covalently closed (CCC) plasmid DNA vectors offer a limited safety profile. They often result in the transfer of unwanted prokaryotic sequences, antibiotic resistance genes, and bacterial origins of replication that may lead to unwanted immunostimulatory responses. Furthermore, such vectors may impart the potential for chromosomal integration, thus potentiating oncogenesis. Linear covalently closed (LCC), bacterial sequence free DNA vectors have shown promising clinical improvements in vitro and in vivo. However, the generation of such minivectors has been limited by in vitro enzymatic reactions hindering their downstream application in clinical trials. We previously characterized an in vivo temperature-inducible expression system, governed by the phage ? pL promoter and regulated by the thermolabile ? CI[Ts]857 repressor to produce recombinant protelomerase enzymes in E. coli. In this expression system, induction of recombinant protelomerase was achieved by increasing culture temperature above the 37°C threshold temperature. Overexpression of protelomerase led to enzymatic reactions, acting on genetically engineered multi-target sites called “Super Sequences” that serve to convert conventional CCC plasmid DNA into LCC DNA minivectors. Temperature up-shift, however, can result in intracellular stress responses and may alter plasmid replication rates; both of which may be detrimental to LCC minivector production. We sought to optimize our one-step in vivo DNA minivector production system under various induction schedules in combination with genetic modifications influencing plasmid replication, processing rates, and cellular heat stress responses. We assessed different culture growth techniques, growth media compositions, heat induction scheduling and temperature, induction duration, post-induction temperature, and E. coli genetic background to improve the productivity and scalability of our system, achieving an overall LCC DNA minivector production efficiency of ?90%.We optimized a robust technology conferring rapid, scalable, one-step in vivo production of LCC DNA minivectors with potential application to gene transfer-mediated therapeutics. PMID:24586704

Wettig, Shawn; Slavcev, Roderick A.

2014-01-01

168

ARTcrystal process for industrial nanocrystal production--optimization of the ART MICCRA pre-milling step.  

PubMed

The ARTcrystal process is a new approach for the production of drug nanocrystals. It is a combination of a special pre-treatment step with subsequent high pressure homogenization (HPH) at low pressures. In the pre-treatment step the particle size is already reduced to the nanometer range by use of the newly developed ART MICCRA rotor-stator system. In this study, the running parameters for the ART MICCRA system are systematically studied, i.e. temperature, stirring speed, flow rate, foaming effects, size of starting material, valve position from 0° to 45°. The antioxidant rutin was used as model drug. Applying optimized parameters, the pre-milling yielded already a nanosuspension with a photon correlation spectroscopy (PCS) diameter of about 650 nm. On lab scale production time was 5 min for 1L nanosuspension (5% rutin content), i.e. the capacity of the setup is also suitable for medium industrial scale production. Compared to other nanocrystal production methods (bead milling, HPH, etc.), similar sizes are achievable, but the process is more cost-effective, faster in time and easily scale-able, thus being an interesting novel process for nanocrystal production on lab and industrial scale. PMID:24556175

Scholz, Patrik; Arntjen, Anja; Müller, Rainer H; Keck, Cornelia M

2014-04-25

169

Optimal Estimation Of Voltage Phasors And Frequency Deviation Using Linear And Non-Linear Kalman Filtering: Theory And Limitations  

Microsoft Academic Search

This paper presents two techniques for optimal tracking of power system voltage phasors and frequency deviation. The first technique is based on a two-state linear Kalman filter model. The second technique is based on a three-state extended Kalman filter model. In the latter the frequency deviation is considered a third state variable and is recursively computed on-line. It is shown

Adly Girgis; T. Daniel Hwang

1984-01-01

170

One step memory of group reputation is optimal to promote cooperation in public goods games  

NASA Astrophysics Data System (ADS)

Individuals' change of social ties has been observed to promote cooperation under specific mechanism, such as success-driven or expectation-driven migration. However, there is no clear criterion or information from players' instinctive memory or experience for them to consult as they would like to change their social ties. For the first time we define the reputation of a group based on individual's memory law. A model is proposed, where all players are endowed with the capacity to adjust interaction ambience involved if the reputation of their environment fails to satisfy their expectations. Simulation results show that cooperation decays as the increase of player's memory depth and one step memory is optimal to promote cooperation, which provides a potential interpretation for that most species memorize their reciprocators over very short time scales. Of intrigue is the result that cooperation can be improved greatly at an optimal interval of moderate expectation. Moreover, cooperation can be established and stabilized within a wide range of model parameters even when players choose their new partners randomly under the combination of reputation and group switching mechanisms. Our work validates the fact that individuals' short memory or experience within a multi-players group acts as an effective ingredient to boost cooperation.

Li, Aming; Wu, Te; Cong, Rui; Wang, Long

2013-08-01

171

Application of digital tomosynthesis (DTS) of optimal deblurring filters for dental X-ray imaging  

NASA Astrophysics Data System (ADS)

Digital tomosynthesis (DTS) is a limited-angle tomographic technique that provides some of the tomographic benefits of computed tomography (CT) but at reduced dose and cost. Thus, the potential for application of DTS to dental X-ray imaging seems promising. As a continuation of our dental radiography R&D, we developed an effective DTS reconstruction algorithm and implemented it in conjunction with a commercial dental CT system for potential use in dental implant placement. The reconstruction algorithm employed a backprojection filtering (BPF) method based upon optimal deblurring filters to suppress effectively both the blur artifacts originating from the out-focus planes and the high-frequency noise. To verify the usefulness of the reconstruction algorithm, we performed systematic simulation works and evaluated the image characteristics. We also performed experimental works in which DTS images of enhanced anatomical resolution were successfully obtained by using the algorithm and were promising to our ongoing applications to dental X-ray imaging. In this paper, our approach to the development of the DTS reconstruction algorithm and the results are described in detail.

Oh, J. E.; Cho, H. S.; Kim, D. S.; Choi, S. I.; Je, U. K.

2012-04-01

172

Structure optimization of an artificial neural filter detecting membrane-spanning amino acid sequences.  

PubMed

An artificial neural network has been developed for the recognition and prediction of transmembrane regions in the amino acid sequences of human integral membrane proteins. It provides an additional prediction method besides the common hydrophobicity analysis by statistical means. Membrane/nonmembrane transition regions are predicted with 92% accuracy in both training and independent test data. The method used for the development of the neural filter is the algorithm of structure evolution. It subjects both the architecture and parameters of the system to a systematical optimization process and carries out local search in the respective structure and parameter spaces. The training technique of incomplete induction as part of the structure evolution provides for a comparatively general solution of the problem that is described by input-output relations only. Seven physiochemical side-chain properties were used to encode the amino acid sequences. It was found that geometric parameters like side-chain volume, bulkiness, or surface area are of minor importance. The properties polarity, refractivity, and hydrophobicity, however, turned out to support feature extraction. It is concluded that membrane transition regions in proteins are encoded in sequences as a characteristic feature based on the respective side-chain properties. The method of structure evolution is described in detail for this particular application and suggestions for further development of amino acid sequence filters are made. PMID:8679941

Lohmann, R; Schneider, G; Wrede, P

1996-01-01

173

Geometric optimization of a step bearing for a hydrodynamically levitated centrifugal blood pump for the reduction of hemolysis.  

PubMed

A hydrodynamically levitated centrifugal blood pump with a semi-open impeller has been developed for mechanical circulatory assistance. However, a narrow bearing gap has the potential to cause hemolysis. The purpose of the present study is to optimize the geometric configuration of the hydrodynamic step bearing in order to reduce hemolysis by expansion of the bearing gap. First, a numerical analysis of the step bearing, based on lubrication theory, was performed to determine the optimal design. Second, in order to assess the accuracy of the numerical analysis, the hydrodynamic forces calculated in the numerical analysis were compared with those obtained in an actual measurement test using impellers having step lengths of 0%, 33%, and 67% of the vane length. Finally, a bearing gap measurement test and a hemolysis test were performed. As a result, the numerical analysis revealed that the hydrodynamic force was the largest when the step length was approximately 70%. The hydrodynamic force calculated in the numerical analysis was approximately equivalent to that obtained in the measurement test. In the measurement test and the hemolysis test, the blood pump having a step length of 67% achieved the maximum bearing gap and reduced hemolysis, as compared with the pumps having step lengths of 0% and 33%. It was confirmed that the numerical analysis of the step bearing was effective, and the developed blood pump having a step length of approximately 70% was found to be a suitable configuration for the reduction of hemolysis. PMID:23834855

Kosaka, Ryo; Yada, Toru; Nishida, Masahiro; Maruyama, Osamu; Yamane, Takashi

2013-09-01

174

Optimization of medium components for increased production of C-phycocyanin from Phormidium ceylanicum and its purification by single step process.  

PubMed

Phycocyanin is a major protein produced by cyanobacteria, but very few phycocyanin-producing strains have been reported. In the present study, response surface methodology (RSM) involving a central composite design for four factors was successfully employed to optimize medium components for increased production of phycocyanin from Phormidium ceylanicum. The production of phycocyanin and interactions between sodium nitrate, calcium chloride, trace metal mix and citric acid stock were investigated and modeled. Under optimized condition P. ceylanicum was able to give 2.3-fold increase in phycocyanin production in comparison to commonly used BG 11 medium in 32 days. We have demonstrated the extraction, purification and characterization of C-phycocyanin using novel method based on filtration and single step chromatography. The protein was extracted by repeated freeze-thaw cycles and the crude extract was filtered and concentrated in stirred ultrafiltration cell (UFC). The UFC concentrate was then subjected to a single ion exchange chromatographic step. A purity ratio of 4.15 was achieved from a starting value of 1.05. The recovery efficiency of C-phycocyanin from crude extract was 63.50%. The purity was checked by electrophoresis and UV-Vis spectroscopy. PMID:18954974

Singh, Niraj Kumar; Parmar, Asha; Madamwar, Datta

2009-02-01

175

A Compact Symmetric Microstrip Filter Based on a Rectangular Meandered-Line Stepped Impedance Resonator with a Triple-Band Bandstop Response  

PubMed Central

This paper presents a symmetric-type microstrip triple-band bandstop filter incorporating a tri-section meandered-line stepped impedance resonator (SIR). The length of each section of the meandered line is 0.16, 0.15, and 0.83 times the guided wavelength (?g), so that the filter features three stop bands at 2.59?GHz, 6.88?GHz, and 10.67?GHz, respectively. Two symmetric SIRs are employed with a microstrip transmission line to obtain wide bandwidths of 1.12, 1.34, and 0.89?GHz at the corresponding stop bands. Furthermore, an equivalent circuit model of the proposed filter is developed, and the model matches the electromagnetic simulations well. The return losses of the fabricated filter are measured to be ?29.90?dB, ?28.29?dB, and ?26.66?dB while the insertion losses are 0.40?dB, 0.90?dB, and 1.10?dB at the respective stop bands. A drastic reduction in the size of the filter was achieved by using a simplified architecture based on a meandered-line SIR. PMID:24319367

Kim, Nam-Young

2013-01-01

176

A compact symmetric microstrip filter based on a rectangular meandered-line stepped impedance resonator with a triple-band bandstop response.  

PubMed

This paper presents a symmetric-type microstrip triple-band bandstop filter incorporating a tri-section meandered-line stepped impedance resonator (SIR). The length of each section of the meandered line is 0.16, 0.15, and 0.83 times the guided wavelength (? g ), so that the filter features three stop bands at 2.59?GHz, 6.88?GHz, and 10.67?GHz, respectively. Two symmetric SIRs are employed with a microstrip transmission line to obtain wide bandwidths of 1.12, 1.34, and 0.89?GHz at the corresponding stop bands. Furthermore, an equivalent circuit model of the proposed filter is developed, and the model matches the electromagnetic simulations well. The return losses of the fabricated filter are measured to be -29.90?dB, -28.29?dB, and -26.66?dB while the insertion losses are 0.40?dB, 0.90?dB, and 1.10?dB at the respective stop bands. A drastic reduction in the size of the filter was achieved by using a simplified architecture based on a meandered-line SIR. PMID:24319367

Dhakal, Rajendra; Kim, Nam-Young

2013-01-01

177

The first on-site evaluation of a new filter optimized for TARC and developer  

NASA Astrophysics Data System (ADS)

In previous studies, we identified filter properties that have a strong effect on microbubble formation on the downstream side of the filter membrane. A new Highly Asymmetric Polyarylsulfone (HAPAS) filter was developed based on the findings. In the current study, we evaluated newly-developed HAPAS filter in environmentally preferred non-PFOS TARC in a laboratory setting. Test results confirmed that microbubble counts downstream of the filter were lower than those of a conventional HDPE filter. Further testing in a manufacturing environment confirmed that HAPAS filtration of TARC at point of use was able to reduce defectivity caused by microbubbles on both unpatterned and patterned wafers, compared with a HDPE filter.

Umeda, Toru; Ishibashi, Takeo; Nakamura, Atsushi; Ide, Junichi; Nagano, Masaru; Omura, Koichi; Tsuzuki, Shuichi; Numaguchi, Toru

2008-11-01

178

A specification language for the optimal design of exotic FIR filters with second-order cone programs  

Microsoft Academic Search

Application-tailored individual and joint FIR-filter designs of remarkable complexity are elegantly coded using our MATLAB toolbox Opt, a research tool providing a DSP-oriented modeling language for driving ultra-efficient off-the-shelf numerical solvers of (linear and) second-order cone programs. Opt data types symbolically capture affine or (nonnegative definite) quadratic dependencies on optimization variables, which gain numeric values only later, when optimized. On

J. O. Coleman; D. P. Scholnik; J. J. Brandriss

2002-01-01

179

Design of Optimal Quincunx Filter Banks for Image Dept. of Elec. and Comp. Engineering, University of Victoria, Victoria, BC, V8W 3P6, Canada  

E-print Network

typically desires filter banks to have perfect reconstruc- tion (PR), linear phase, high coding gain, good methods have been proposed. Variable transformation methods are commonly used for the design of 2D filter1 Design of Optimal Quincunx Filter Banks for Image Coding Yi Chen Dept. of Elec. and Comp

Adams, Michael D.

180

Optimization of Temporal Filters in the Modulation Frequency Domain via Constrained Linear Discriminant Analysis (C-LDA) for Constructing Robust Features in Speech Recognition  

Microsoft Academic Search

Data-driven temporal filtering approaches based on a specific optimization criterion have been shown to be capable of enhancing the discrimination and robustness of speech features in speech recognition. The filters in these approaches are often obtained with the statistics of the features in the temporal domain. In this paper, we derive new data-driven temporal filters that employ the statistics of

Jeih-weih Hung; Nantou Hsien

2007-01-01

181

An Explicit Linear Filtering Solution for the Optimization of Guidance Systems with Statistical Inputs  

NASA Technical Reports Server (NTRS)

The determination of optimum filtering characteristics for guidance system design is generally a tedious process which cannot usually be carried out in general terms. In this report a simple explicit solution is given which is applicable to many different types of problems. It is shown to be applicable to problems which involve optimization of constant-coefficient guidance systems and time-varying homing type systems for several stationary and nonstationary inputs. The solution is also applicable to off-design performance, that is, the evaluation of system performance for inputs for which the system was not specifically optimized. The solution is given in generalized form in terms of the minimum theoretical error, the optimum transfer functions, and the optimum transient response. The effects of input signal, contaminating noise, and limitations on the response are included. From the results given, it is possible in an interception problem, for example, to rapidly assess the effects on minimum theoretical error of such factors as target noise and missile acceleration. It is also possible to answer important questions regarding the effect of type of target maneuver on optimum performance.

Stewart, Elwood C.

1961-01-01

182

Bounds on the performance of optimal four-dimensional filters for detection of low-contrast IR point targets  

Microsoft Academic Search

This paper provides analytic expressions for the performance of optimal matched filters designed to utilize spatial, temporal, and spectral observations of point targets against cluttered backgrounds. The analysis explicitly treats the situation of bipolar low contrast target signatures typical in advanced infrared systems such as the infrared search and track systems. In these cases, one must include the temporal effects

Martin R. Wohlers

1991-01-01

183

IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS--II: EXPRESS BRIEFS, VOL. 51, NO. 3, MARCH 2004 105 Continuous-Time Filter Design Optimized for  

E-print Network

IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS--II: EXPRESS BRIEFS, VOL. 51, NO. 3, MARCH 2004 105 Continuous-Time Filter Design Optimized for Reduced Die Area Charles Myers, Student Member, IEEE, Brandon for distributing capacitor and resistor area to optimally reduce die area in a given continuous-time filter design

Moon, Un-Ku

184

Modeling the impact of drought on canopy carbon and water fluxes for a subtropical evergreen coniferous plantation in southern China through parameter optimization using an ensemble Kalman filter  

NASA Astrophysics Data System (ADS)

Soil and atmospheric water deficits have significant influences on CO2 and energy exchanges between the atmosphere and terrestrial ecosystems. Model parameterization significantly affects the ability of a model to simulate carbon, water, and energy fluxes. In this study, an ensemble Kalman filter (EnKF) and observations of gross primary productivity (GPP) and latent heat (LE) fluxes were used to optimize model parameters significantly affecting the calculation of these fluxes for a subtropical coniferous plantation in southeastern China. The optimized parameters include the maximum carboxylation rate (Vcmax), the slope in the modified Ball-Berry model (M) and the coefficient determining the sensitivity of stomatal conductance to atmospheric water vapor deficit (D0). Optimized Vcmax and M showed larger variations than D0. Seasonal variations of Vcmax and M were more pronounced than the variations between the two years. Vcmax and M were associated with soil water content (SWC). During dry periods, SWC at the 20 cm depth explained 61% and 64% of variations of Vcmax and M, respectively. EnKF parameter optimization improved the simulations of GPP, LE and SH, mainly during dry periods. After parameter optimization using EnKF, the variations of GPP, LE and SH explained by the model increased by 1% to 4% at half-hourly steps and by 3% to 5% at daily time steps. Further efforts are needed to differentiate the real causes of parameter variations and improve the ability of models to describe the change of stomatal conductance with net photosynthesis rate and the sensitivity of photosynthesis capacity to soil water stress under different environmental conditions.

Ju, W.; Wang, S.; Yu, G.; Zhou, Y.; Wang, H.

2010-03-01

185

A High Voltage and High Power Adjustable Speed Drive System Using the Integrated and Step-Up Transforming Filter  

Microsoft Academic Search

A filter device is indispensable in most ac adjustable speed drive systems to eliminate the high-frequency components in the output voltage of an inverter, which could protect the insulation of the ac motor and reduce electromagnetic interference. Additionally, due to the restraints of power electronic devices, especially in the high voltage and high power systems with neutral point clamped (NPC)

Bai Hua; Zhao Zhengming; Yuan Liqiang; Li Bing

2006-01-01

186

An Optimal Orthogonal Decomposition Method for Kalman Filter-Based Turbofan Engine Thrust Estimation  

NASA Technical Reports Server (NTRS)

A new linear point design technique is presented for the determination of tuning parameters that enable the optimal estimation of unmeasured engine outputs such as thrust. The engine s performance is affected by its level of degradation, generally described in terms of unmeasurable health parameters related to each major engine component. Accurate thrust reconstruction depends upon knowledge of these health parameters, but there are usually too few sensors to be able to estimate their values. In this new technique, a set of tuning parameters is determined which accounts for degradation by representing the overall effect of the larger set of health parameters as closely as possible in a least squares sense. The technique takes advantage of the properties of the singular value decomposition of a matrix to generate a tuning parameter vector of low enough dimension that it can be estimated by a Kalman filter. A concise design procedure to generate a tuning vector that specifically takes into account the variables of interest is presented. An example demonstrates the tuning parameters ability to facilitate matching of both measured and unmeasured engine outputs, as well as state variables. Additional properties of the formulation are shown to lend themselves well to diagnostics.

Litt, Jonathan S.

2005-01-01

187

Optimizing single mode robustness of the distributed modal filtering rod fiber amplifier.  

PubMed

High-power fiber amplifiers for pulsed applications require large mode area (LMA) fibers having high pump absorption and near diffraction limited output. Photonic crystal fibers allow realization of short LMA fiber amplifiers having high pump absorption through a pump cladding that is decoupled from the outer fiber diameter. However, achieving ultra low NA for single mode (SM) guidance is challenging, thus different design strategies must be applied. The distributed modal filtering (DMF) design enables SM guidance in ultra low NA fibers with very large cores, where large preform tolerances can be compensated during the fiber draw. Design optimization of the SM bandwidth of the DMF rod fiber is presented. Analysis of band gap properties results in a fourfold increase of the SM bandwidth compared to previous results, achieved by utilizing the first band of cladding modes, which can cover a large fraction of the Yb emission band including wavelengths of 1030 nm and 1064 nm. Design parameters tolerating refractive index fabrication uncertainties of ± 10?? are targeted to yield stable SM bandwidths. PMID:22453408

Jørgensen, Mette Marie; Petersen, Sidsel Rübner; Laurila, Marko; Lægsgaard, Jesper; Alkeskjold, Thomas Tanggaard

2012-03-26

188

An Optimal Orthogonal Decomposition Method for Kalman Filter-Based Turbofan Engine Thrust Estimation  

NASA Technical Reports Server (NTRS)

A new linear point design technique is presented for the determination of tuning parameters that enable the optimal estimation of unmeasured engine outputs, such as thrust. The engine s performance is affected by its level of degradation, generally described in terms of unmeasurable health parameters related to each major engine component. Accurate thrust reconstruction depends on knowledge of these health parameters, but there are usually too few sensors to be able to estimate their values. In this new technique, a set of tuning parameters is determined that accounts for degradation by representing the overall effect of the larger set of health parameters as closely as possible in a least-squares sense. The technique takes advantage of the properties of the singular value decomposition of a matrix to generate a tuning parameter vector of low enough dimension that it can be estimated by a Kalman filter. A concise design procedure to generate a tuning vector that specifically takes into account the variables of interest is presented. An example demonstrates the tuning parameters ability to facilitate matching of both measured and unmeasured engine outputs, as well as state variables. Additional properties of the formulation are shown to lend themselves well to diagnostics.

Litt, Jonathan S.

2007-01-01

189

An Optimal Orthogonal Decomposition Method for Kalman Filter-Based Turbofan Engine Thrust Estimation  

NASA Technical Reports Server (NTRS)

A new linear point design technique is presented for the determination of tuning parameters that enable the optimal estimation of unmeasured engine outputs, such as thrust. The engine's performance is affected by its level of degradation, generally described in terms of unmeasurable health parameters related to each major engine component. Accurate thrust reconstruction depends on knowledge of these health parameters, but there are usually too few sensors to be able to estimate their values. In this new technique, a set of tuning parameters is determined that accounts for degradation by representing the overall effect of the larger set of health parameters as closely as possible in a least squares sense. The technique takes advantage of the properties of the singular value decomposition of a matrix to generate a tuning parameter vector of low enough dimension that it can be estimated by a Kalman filter. A concise design procedure to generate a tuning vector that specifically takes into account the variables of interest is presented. An example demonstrates the tuning parameters ability to facilitate matching of both measured and unmeasured engine outputs, as well as state variables. Additional properties of the formulation are shown to lend themselves well to diagnostics.

Litt, Jonathan S.

2007-01-01

190

Matched filter optimization of kSZ measurements with a reconstructed cosmological flow field  

E-print Network

We develop and test a new statistical method to measure the kinematic Sunyaev-Zel'dovich (kSZ) effect. A sample of independently detected clusters is combined with the cosmic flow field predicted from a galaxy redshift survey in order to derive a matched filter that optimally weights the kSZ signal for the sample as a whole given the noise involved in the problem. We apply this formalism to realistic mock microwave skies based on cosmological N-body simulations, and demonstrate its robustness and performance. In particular, we carefully assess the various sources of uncertainty, CMB primary fluctuations, instrumental noise, uncertainties in the determination of the velocity field, and effects introduced by miscentering of clusters and by scatter in the mass-observable relations. We show that available data (Planck maps and the MaxBCG catalogue) should deliver a $7.7\\sigma$ detection of the kSZ. A similar cluster catalogue with broader sky coverage should increase the detection significance to $\\sim 13\\sigma$....

Li, Ming; White, Simon D M; Jasche, Jens

2014-01-01

191

Improvement of hemocompatibility for hydrodynamic levitation centrifugal pump by optimizing step bearings.  

PubMed

We have developed a hydrodynamic levitation centrifugal blood pump with a semi-open impeller for a mechanically circulatory assist. The impeller levitated with original hydrodynamic bearings without any complicated control and sensors. However, narrow bearing gap has the potential for causing hemolysis. The purpose of the study is to investigate the geometric configuration of the hydrodynamic step bearing to minimize hemolysis by expansion of the bearing gap. Firstly, we performed the numerical analysis of the step bearing based on Reynolds equation, and measured the actual hydrodynamic force of the step bearing. Secondly, the bearing gap measurement test and the hemolysis test were performed to the blood pumps, whose step length were 0 %, 33 % and 67 % of the vane length respectively. As a result, in the numerical analysis, the hydrodynamic force was the largest, when the step bearing was around 70 %. In the actual evaluation tests, the blood pump having step 67 % obtained the maximum bearing gap, and was able to improve the hemolysis, compared to those having step 0% and 33%. We confirmed that the numerical analysis of the step bearing worked effectively, and the blood pump having step 67 % was suitable configuration to minimize hemolysis, because it realized the largest bearing gap. PMID:22254562

Kosaka, Ryo; Yada, Toru; Nishida, Masahiro; Maruyama, Osamu; Yamane, Takashi

2011-01-01

192

Optimization of SERS scattering by Ag-NPs-coated filter paper for quantification of nicotinamide in a cosmetic formulation.  

PubMed

Supported silver nanoparticles on filter paper were synthesized using Tollens' reagent. Experimental designs were performed to obtain the highest SERS enhancement factor by study of the influence of the parameters: filter paper pretreatment, type of filter paper, reactants concentration, reaction time and temperature. To this end, fractional factorial and central composite designs were used in order to optimize the synthesis for quantification of nicotinamide in the presence of excipients in a commercial sample of cosmetic. The values achieved for the optimal condition were 150 mM of ammonium hydroxide, 50 mM of silver nitrate, 500 mM of glucose, 8 min for the reaction time, 45 °C temperature, pretreatment with ammonium hydroxide and quantitative filter paper (1-2 µm). Despite the variation of SERS intensity, it was possible to use an adapted method of internal standard to obtain a calibration curve with good precision. The coefficient of determination of the linear fit was 0.97. The method proposed in this work was capable of quantifying nicotinamide on a commercial cosmetic gel, at low concentration levels, with a relative error of 1.06% compared to the HPLC. SERS spectroscopy presents faster analyses than HPLC, also complex sample preparation and large amount of reactants are not necessary. PMID:24274308

Sallum, Loriz Francisco; Soares, Frederico Luis Felipe; Ardila, Jorge Armando; Carneiro, Renato Lajarim

2014-01-01

193

Towards Protein Crystallization as a Process Step in Downstream Processing of Therapeutic Antibodies: Screening and Optimization at Microbatch Scale  

Microsoft Academic Search

Crystallization conditions of an intact monoclonal IgG4 (immunoglobulin G, subclass 4) antibody were established in vapor diffusion mode by sparse matrix screening and subsequent optimization. The procedure was transferred to microbatch conditions and a phase diagram was built showing surprisingly low solubility of the antibody at equilibrium. With up-scaling to process scale in mind, purification efficiency of the crystallization step

Yuguo Zang; Bernd Kammerer; Maike Eisenkolb; Katrin Lohr; Hans Kiefer; Sue Cotterill

2011-01-01

194

Increasing high-throughput discovery bioanalysis using automated selected reaction monitoring compound optimization, ultra-high-pressure liquid chromatography, and single-step sample preparation workflows.  

PubMed

QuickQuan is an integrated software package for Thermo Scientific triple quadrupole mass spectrometers that allows users to automate routine operations ranging from method development to data processing. QuickQuan automated optimization of compound-selected reaction monitoring (SRM) transitions by evaluating both positive and negative polarities during an infusion. Whichever mode produces the most intense Q1 scan is then carried to product ion spectra. QuickQuan then writes these SRM methods to a shared network database. The total volume of compound needed is 100 microL infused over approximately 1.6 min. The auto-optimization is carried out in 96-well plates and does not require an operator present. The SRM database was shared between two identical TSQ Quantum mass spectrometers. For data acquisition, QuickQuan automatically created a sequence file complete with a data processing method pre-populated with compound IDs and corresponding SRM transitions. To increase throughput we coupled each Finnigan Quantum with ultra-high-pressure liquid chromatography (uHPLC) accomplished using 4x Ultra Flux quaternary pumps that were designed to handle pressures up to 15 000 psi. The total run time for all analyses was 1.2 min using BEH 1.7 microm particle C18 columns. Further time reductions were realized with sample preparation accomplished using Strata Impact protein precipitation plates which provided an in-well protein crash and 0.20 micron filtering in a one-step process. Pharmacokinetic data turnaround time was significantly improved by combining these three techniques of automated method development with the speed efficiency of uHPLC and a single step in well sample preparation. PMID:19813283

Smalley, James; Xin, Baomin; Olah, Timothy V

2009-11-01

195

An interior algorithm for nonlinear optimization that combines line search and trust region steps  

Microsoft Academic Search

.  An interior-point method for nonlinear programming is presented. It enjoys the flexibility of switching between a line search\\u000a method that computes steps by factoring the primal-dual equations and a trust region method that uses a conjugate gradient\\u000a iteration. Steps computed by direct factorization are always tried first, but if they are deemed ineffective, a trust region\\u000a iteration that guarantees progress

Richard A. Waltz; José Luis Morales; Jorge Nocedal; Dominique Orban

2006-01-01

196

Toward an Optimal Position for IVC Filters: Computational Modeling of the Impact of Renal Vein Inflow  

SciTech Connect

The purpose of this report is to evaluate the hemodynamic effects of renal vein inflow and filter position on unoccluded and partially occluded IVC filters using three-dimensional computational fluid dynamics. Three-dimensional models of the TrapEase and Gunther Celect IVC filters, spherical thrombi, and an IVC with renal veins were constructed. Hemodynamics of steady-state flow was examined for unoccluded and partially occluded TrapEase and Gunther Celect IVC filters in varying proximity to the renal veins. Flow past the unoccluded filters demonstrated minimal disruption. Natural regions of stagnant/recirculating flow in the IVC are observed superior to the bilateral renal vein inflows, and high flow velocities and elevated shear stresses are observed in the vicinity of renal inflow. Spherical thrombi induce stagnant and/or recirculating flow downstream of the thrombus. Placement of the TrapEase filter in the suprarenal vein position resulted in a large area of low shear stress/stagnant flow within the filter just downstream of thrombus trapped in the upstream trapping position. Filter position with respect to renal vein inflow influences the hemodynamics of filter trapping. Placement of the TrapEase filter in a suprarenal location may be thrombogenic with redundant areas of stagnant/recirculating flow and low shear stress along the caval wall due to the upstream trapping position and the naturally occurring region of stagnant flow from the renal veins. Infrarenal vein placement of IVC filters in a near juxtarenal position with the downstream cone near the renal vein inflow likely confers increased levels of mechanical lysis of trapped thrombi due to increased shear stress from renal vein inflow.

Wang, S L; Singer, M A

2009-07-13

197

Nature-inspired optimization of quasicrystalline arrays and all-dielectric optical filters and metamaterials  

NASA Astrophysics Data System (ADS)

Quasicrystalline solids were first observed in nature in 1980s. Their lattice geometry is devoid of translational symmetry; however it possesses long-range order as well as certain orders of rotational symmetry forbidden by translational symmetry. Mathematically, such lattices are related to aperiodic tilings. Since their discovery there has been great interest in utilizing aperiodic geometries for a wide variety of electromagnetic (EM) and optical applications. The first thrust of this dissertation addresses applications of quasicrystalline geometries for wideband antenna arrays and plasmonic nano-spherical arrays. The first application considered is the design of suitable antenna arrays for micro-UAV (unmanned aerial vehicle) swarms based on perturbation of certain types of aperiodic tilings. Due to safety reasons and to avoid possible collision between micro-UAVs it is desirable to keep the minimum separation distance between the elements several wavelengths. As a result typical periodic planar arrays are not suitable, since for periodic arrays increasing the minimum element spacing beyond one wavelength will lead to the appearance of grating lobes in the radiation pattern. It will be shown that using this method antenna arrays with very wide bandwidths and low sidelobe levels can be designed. It will also be shown that in conjunction with a phase compensation method these arrays show a large degree of versatility to positional noise. Next aperiodic aggregates of gold nano-spheres are studied. Since traditional unit cell approaches cannot be used for aperiodic geometries, we start be developing new analytical tools for aperiodic arrays. A modified version of generalized Mie theory (GMT) is developed which defines scattering coefficients for aperiodic spherical arrays. Next two specific properties of quasicrystalline gold nano-spherical arrays are considered. The optical response of these arrays can be explained in terms of the grating response of the array (photonic resonance) and the plasmonic response of the spheres (plasmonic resonance). In particular the couplings between the photonic and plasmonic modes are studied. In periodic arrays this coupling leads to the formation of a so called photonic-plasmonic hybrid mode. The formation of hybrid modes is studied in quasicrystalline arrays. Quasicrystalline structures in essence possess several periodicities which in some cases can lead to the formation of multiple hybrid modes with wider bandwidths. It is also demonstrated that the performance of these arrays can be further enhanced by employing a perturbation method. The second property considered is local field enhancements in quasicrystalline arrays of gold nanospheres. It will be shown that despite a considerably smaller filling factor quasicrystalline arrays generate larger local field enhancements which can be even further enhanced by optimally placing perturbing spheres within the prototiles that comprise the aperiodic arrays. The second thrust of research in this dissertation focuses on designing all-dielectric filters and metamaterial coatings for the optical range. In higher frequencies metals tend to have a high loss and thus they are not suitable for many applications. Hence dielectrics are used for applications in optical frequencies. In particular we focus on designing two types of structures. First a near-perfect optical mirror is designed. The design is based on optimizing a subwavelength periodic dielectric grating to obtain appropriate effective parameters that will satisfy the desired perfect mirror condition. Second, a broadband anti-reflective all-dielectric grating with wide field of view is designed. The second design is based on a new computationally efficient genetic algorithm (GA) optimization method which shapes the sidewalls of the grating based on optimizing the roots of polynomial functions.

Namin, Frank Farhad A.

198

Miniaturization and Optimization of RF SAW Filter Using Wafer Level Packaging Technology  

Microsoft Academic Search

In this paper, we describes the wafer level surface acoustic wave (SAW) filter package, 1.0times0.8 mm2, which is applicable for radio frequency (RF) stage in mobile phones. The SAW filter is reduced in size and thickness by using a 4\\

Tae Hoon Kim; Won Kyu Jeung; Si Joong Yang; Seog Moon Choi; Seung Wook Park; Hyun Ho Kim; J. Ha; Mi Jin Park; S. Kao; J. P. Hong; Sung Yi; Jun Sik Hwang; Ji Hyuk Lim; Woon Bae Kim

2007-01-01

199

Linear variable filter optimization for emergency response chemical detection and discrimination  

Microsoft Academic Search

Linear variable filter design and fabrication for LWIR is now commercially available for use in the development of remote sensing systems. The linear variable filter is attached directly to the cold shield of the focal plane array. The resulting compact spectrometer assemblies are completely contained in the Dewar system. This approach eliminates many of the wavelength calibration problems associated with

Sylvia S. Shen; Paul E. Lewis

2010-01-01

200

Multi-bandwidth frequency selective surfaces for near infrared filtering: design and optimization  

Microsoft Academic Search

The design of sub-millimeter filters follows the design methods used in the microwave region. Exacting modal matching, integral equation or finite element methods can be used for design. A major difference though is the introduction of material parameters and thicknesses that may not be important in longer wavelength designs. This paper describes the design of multibandwidth filters operating in the

Tom Cwik; S. Fernandez; A. Ksendzova; Clayton C. La Baw; Paul D. Maker; Richard E. Muller

1999-01-01

201

Common spatial pattern patches - An optimized filter ensemble for adaptive brain-computer interfaces  

Microsoft Academic Search

Laplacian filters are commonly used in Brain Computer Interfacing (BCI). When only data from few channels are available, or when, like at the beginning of an experiment, no previous data from the same user is available complex features cannot be used. In this case band power features calculated from Laplacian filtered channels represents an easy, robust and general feature to

Claudia Sannelli; C. Vidaurre; K.-R. Muller; B. Blankertz

2010-01-01

202

Optimization of the LMS Subband, Adaptive Filter System Phillip L. De Len  

E-print Network

University Klipsch School of Electrical and Computer Engineering Las Cruces, New Mexico 88003-8001 ABSTRACT filters, g0, ,gM-1 . The computational benefit of this technique results from the fact that the subband is equivalently and efficiently implemented with the polyphase uniform DFT filter bank

De Leon, Phillip

203

Optimal convolutive filters for real-time detection and arrival time estimation of transient signals  

Microsoft Academic Search

Linear convolutive filters are fast in calculation and in application, and thus, often used for real-time processing of continuous data streams. In the case of transient signals, a filter has not only to detect the presence of a specific waveform, but to estimate its arrival time as well. In this study, a measure is presented which indicates the performance of

Michal Natora; Felix Franke; Klaus Obermayer

2009-01-01

204

Optimal-tradeoff circular harmonic function filters for 3D target recognition  

NASA Astrophysics Data System (ADS)

3D target recognition is of significant interest because representing the object in 3D space couuld essentially provide a solution to pose variation and self-occlusion problems that are big challenges in 2D pattern recognition. Correlation filers have been used in a variety of 2D pattern matching applications and many correlation filter designs have been developed to handle problems such as rotations. Correlation filters also offer other benefits such as shift-invariance, graceful degradation and closed-form solutions. The 3D extension of correlation filter is a natural extension to handle 3D pattern recognition problem. In this paper, we propose a 3D correlation filter design method based on cylindrical circular harmonic function (CCHF) and use LADAR imagery to illustrate the good performance of CCHF filters.

Vijaya Kumar, Bhagavatula V. K.; Xie, Chunyan; Mahalanobis, Abhijit

2003-09-01

205

Particle Swarm Optimization and Varying Chemotactic Step-Size Bacterial Foraging Optimization Algorithms Based Dynamic Economic Dispatch with Non-smooth Fuel Cost Functions  

NASA Astrophysics Data System (ADS)

The Dynamic economic dispatch (DED) problem is an optimization problem with an objective to determine the optimal combination of power outputs for all generating units over a certain period of time in order to minimize the total fuel cost while satisfying dynamic operational constraints and load demand in each interval. Recently social foraging behavior of Escherichia coli bacteria has been explored to develop a novel algorithm for distributed optimization and control. The Bacterial Foraging Optimization Algorithm (BFOA) is currently gaining popularity in the community of researchers, for its effectiveness in solving certain difficult real-world optimization problems. This article comes up with a hybrid approach involving Particle Swarm Optimization (PSO) and BFO algorithms with varying chemo tactic step size for solving the DED problem of generating units considering valve-point effects. The proposed hybrid algorithm has been extensively compared with those methods reported in the literature. The new method is shown to be statistically significantly better on two test systems consisting of five and ten generating units.

Praveena, P.; Vaisakh, K.; Rama Mohana Rao, S.

206

A two-step optimization approach for job shop scheduling problem ...  

E-print Network

Keywords: Scheduling; Discrete Optimization; Genetic Algorithm; Job Shop; heuristics. 1. ... JSSP, such as simulated annealing (SA) (Lourenço 1995), tabu search (TS) (Nowicki and Smutnicki ..... A very fast TS/SA algorithm for the job shop.

JJM

2013-01-16

207

Identifying the Preferred Subset of Enzymatic Profiles in Nonlinear Kinetic Metabolic Models via Multiobjective Global Optimization and Pareto Filters  

PubMed Central

Optimization models in metabolic engineering and systems biology focus typically on optimizing a unique criterion, usually the synthesis rate of a metabolite of interest or the rate of growth. Connectivity and non-linear regulatory effects, however, make it necessary to consider multiple objectives in order to identify useful strategies that balance out different metabolic issues. This is a fundamental aspect, as optimization of maximum yield in a given condition may involve unrealistic values in other key processes. Due to the difficulties associated with detailed non-linear models, analysis using stoichiometric descriptions and linear optimization methods have become rather popular in systems biology. However, despite being useful, these approaches fail in capturing the intrinsic nonlinear nature of the underlying metabolic systems and the regulatory signals involved. Targeting more complex biological systems requires the application of global optimization methods to non-linear representations. In this work we address the multi-objective global optimization of metabolic networks that are described by a special class of models based on the power-law formalism: the generalized mass action (GMA) representation. Our goal is to develop global optimization methods capable of efficiently dealing with several biological criteria simultaneously. In order to overcome the numerical difficulties of dealing with multiple criteria in the optimization, we propose a heuristic approach based on the epsilon constraint method that reduces the computational burden of generating a set of Pareto optimal alternatives, each achieving a unique combination of objectives values. To facilitate the post-optimal analysis of these solutions and narrow down their number prior to being tested in the laboratory, we explore the use of Pareto filters that identify the preferred subset of enzymatic profiles. We demonstrate the usefulness of our approach by means of a case study that optimizes the ethanol production in the fermentation of Saccharomyces cerevisiae. PMID:23028457

Pozo, Carlos; Guillen-Gosalbez, Gonzalo; Sorribas, Albert; Jimenez, Laureano

2012-01-01

208

Optimal filter design for shielded and unshielded ambient noise reduction in fetal magnetocardiography  

NASA Astrophysics Data System (ADS)

The greatest impediment to extracting high-quality fetal signals from fetal magnetocardiography (fMCG) is environmental magnetic noise, which may have peak-to-peak intensity comparable to fetal QRS amplitude. Being an unstructured Gaussian signal with large disturbances at specific frequencies, ambient field noise can be reduced with hardware-based approaches and/or with software algorithms that digitally filter magnetocardiographic recordings. At present, no systematic evaluation of filters' performances on shielded and unshielded fMCG is available. We designed high-pass and low-pass Chebychev II-type filters with zero-phase and stable impulse response; the most commonly used band-pass filters were implemented combining high-pass and low-pass filters. The achieved ambient noise reduction in shielded and unshielded recordings was quantified, and the corresponding signal-to-noise ratio (SNR) and signal-to-distortion ratio (SDR) of the retrieved fetal signals was evaluated. The study regarded 66 fMCG datasets at different gestational ages (22-37 weeks). Since the spectral structures of shielded and unshielded magnetic noise were very similar, we concluded that the same filter setting might be applied to both conditions. Band-pass filters (1.0-100 Hz) and (2.0-100 Hz) provided the best combinations of fetal signal detection rates, SNR and SDR; however, the former should be preferred in the case of arrhythmic fetuses, which might present spectral components below 2 Hz.

Comani, S.; Mantini, D.; Alleva, G.; Di Luzio, S.; Romani, G. L.

2005-12-01

209

System optimization of a field-widened Michelson interferometric spectral filter for high spectral resolution lidar  

Microsoft Academic Search

High spectral resolution lidars (HSRLs) have recently shown great value in aerosol measurements form aircraft and are being called for in future space-based aerosol remote sensing applications. A quasi-monolithic field-widened, off-axis Michelson interferometer had been developed as the spectral discrimination filter for an HSRL currently under development at NASA Langley Research Center (LaRC). The Michelson filter consists of a cubic

Dong Liu; Ian Miller; Chris Hostetler; Anthony Cook; Johnathan Hair

2011-01-01

210

Fabrication and optimization of wafer level SAW filter package using laser via drilling  

Microsoft Academic Search

Wafer level surface acoustic wave (SAW) filter package, 0.8times0.6 mm2, is drilled by laser via process. Via formation for interconnection is based on smaller package manufacture. LT (LiTaO3) which is base material of SAW filter is difficult to drill a small via by RIE (Reactive Ion Etching) because the RIE gets a very small etch rate and has wafer broken

Seung Wook Park; Ju Pyo Hong; Tae Hoon Kim; Si Joong Yang; Job Ha; Tae Ho Kim; Sang Wook Park; Young Do Kweon; Sung Yi

2008-01-01

211

Daily Time Step Refinement of Optimized Flood Control Rule Curves for a Global Warming Scenario  

Microsoft Academic Search

Pacific Northwest temperatures have warmed by 0.8 °C since 1920 and are predicted to further increase in the 21st century. Simulated streamflow timing shifts associated with climate change have been found in past research to degrade water resources system performance in the Columbia River Basin when using existing system operating policies. To adapt to these hydrologic changes, optimized flood control

S. Lee; C. Fitzgerald; A. F. Hamlet; S. J. Burges

2009-01-01

212

Towards Protein Crystallization as a Process Step in Downstream Processing of Therapeutic Antibodies: Screening and Optimization at Microbatch Scale  

PubMed Central

Crystallization conditions of an intact monoclonal IgG4 (immunoglobulin G, subclass 4) antibody were established in vapor diffusion mode by sparse matrix screening and subsequent optimization. The procedure was transferred to microbatch conditions and a phase diagram was built showing surprisingly low solubility of the antibody at equilibrium. With up-scaling to process scale in mind, purification efficiency of the crystallization step was investigated. Added model protein contaminants were excluded from the crystals to more than 95%. No measurable loss of Fc-binding activity was observed in the crystallized and redissolved antibody. Conditions could be adapted to crystallize the antibody directly from concentrated and diafiltrated cell culture supernatant, showing purification efficiency similar to that of Protein A chromatography. We conclude that crystallization has the potential to be included in downstream processing as a low-cost purification or formulation step. PMID:21966480

Zang, Yuguo; Kammerer, Bernd; Eisenkolb, Maike; Lohr, Katrin; Kiefer, Hans

2011-01-01

213

Two step derivatization for the analyses of organic, amino acids and glycines on filter paper plasma by GC-MS/SIM.  

PubMed

A rapid dried-filter paper plasma-spot analytical method was developed to quantify organic acids, amino acids, and glycines simultaneously in a two-step derivatization procedure with good sensitivity and specificity. The new method involves a two-step trimethylsilyl (TMS) - trifluoroacyl (TFA) derivatization procedure using GC-MS/ selective ion monitoring (GC-MS/SIM). The dried-filter paper plasma was fortified with an internal standard (tropate) as well as a standard mixture of distilled water and methanol. Methyl orange was added to the residue as an indicator. N-methyl-N-(trimethylsilyl-trifluoroacetamide) and N-methyl-bis-trifluoroacetamide were then added and heated to 60 degrees C for 10 and 15 min to produce the TMS and TFA derivatives, respectively. Using this method, the silylation of carboxylic functional groups was carried out, which was followed by the trifluoroacyl derivatization of the amino functional group. The derivatives were analyzed by GC-MS/SIM. A calibration cure showed a linear relationship for the target compounds between concentrations of 10-500 ng/mL. The limit of detection and quantification on a plasma spot were 10-90 ng/mL (S/N=9) and 80-500 ng/ mL, respectively. The correlation coefficient ranged from 0.938 and 0.999. When applied to the samples from positive patients, the method clearly differentiated normal subjects from the patients with various metabolic disorders such as PKU, MSUD, OTC and a Propionic Aciduria. The new developed method might be useful for making a rapid, sensitive and simultaneous diagnosis of inherited organic and amino acid disorders. In addition, this method is expected to be an alternative method for screening newborns for metabolic disorders in laboratories where expensive MS/MS is unavailable. PMID:17424948

Yoon, Hye-Ran

2007-03-01

214

Discrete Optimization A filter-and-fan approach to the job shop scheduling problem  

Microsoft Academic Search

The job shop scheduling problem (JSSP) is a notoriously difficult problem in combinatorial optimization. Extensive investigation has been devoted to developing efficient algorithms to find optimal or near-optimal solutions. This paper proposes a new heuristic algorithm for the JSSP that effectively combines the classical shifting bottleneck procedure (SBP) with a dynamic and adaptive neighborhood search procedure. Our new search method,

Cesar Rego; Renato Duarte

215

An approach for modeling and optimizing multi-receiver photovoltaic systems with optical filters  

Microsoft Academic Search

Modeling of photovoltaic systems before implementing them is very important for predicting their response under the real conditions; and thus, optimizing them. Many commercial packages are available for modeling and optimizing single-junction and multi-junction solar cells. These packages have been used for modeling and optimizing tandem solar cells, which consist of many cells stacked on each other. However, their features

Alaeddine Mokri; Mahieddine Emziane

2010-01-01

216

What is the optimal therapy for Crohn's disease: step-up or top-down?  

PubMed

Crohn's disease (CD) is an idiopathic chronic inflammatory disorder of the digestive tract, which is incurable. Present therapeutic guidelines follow a sequential step-up approach that focuses on treating acute disease or 'inducing clinical remission' and subsequently aims to 'maintain clinical response'. In view of the chronic relapsing-remitting disabling disease course, new treatment approaches have been sought with the ultimate end point of disease course modification and mucosal healing. A recent preliminary study from D'Haens et al. has provided evidence suggesting that reversing the treatment paradigm from a 'step-up' to a 'top-down' approach may positively alter the natural course of this illness. Their findings indicate that early use of biologic therapy, in combination with immunomodulators, resulted in remission occuring more rapidly than the conventional 'step-up' treatment, with a longer time period to relapse, a decreased need for treatment with corticosteroids, a faster reduction in clinical symptoms, rapid decline in biochemical inflammatory markers (C-reactive protein) and improved endoscopic mucosal healing. These results, supported by previous studies on infliximab use, may hold a promising outcome of fewer stricturing complications, hospitalizations and surgeries for patients with CD. However, we need to better define the timing and candidates for the 'top-down' approach as we are still uncertain about the safety data and the long-term benefits if biologic agents are given as routine maintenance treatment, since most of the trials in CD have been short term, and approximately 30% of patients might have been overtreated. Future clinical trials will be crucial in answering these questions. PMID:20350264

Lin, Ming Valerie; Blonski, Wojciech; Lichtenstein, Gary R

2010-04-01

217

Optimization of a femtosecond Ti : sapphire amplifier using a acouto-optic programmable dispersive filter and a genetic algorithm.  

SciTech Connect

The temporal output of a Ti:Sapphire laser system has been optimized using an acousto-optic programmable dispersive filter and a genetic algorithm. In-situ recording the evolution of spectral phase, amplitude and temporal pulse profile for each iteration of the algorithm using SPIDER shows that we are able to lock the spectral phase of the laser pulse within a narrow margin. By using the second harmonic of the CPA laser as feedback for the genetic algorithm, it has been demonstrated that severe mismatch between the compressor and stretcher can be compensated for in a short period of time.

Korovyanko, O. J.; Rey-de-Castro, R.; Elles, C. G.; Crowell, R. A.; Li, Y.

2006-01-01

218

Optimization of the secondary drying step in freeze drying using TDLAS technology.  

PubMed

The secondary drying phase in freeze drying is mostly developed on a trial-and-error basis due to the lack of appropriate noninvasive process analyzers. This study describes for the first time the application of Tunable Diode Laser Absorption Spectroscopy, a spectroscopic and noninvasive sensor for monitoring secondary drying in laboratory-scale freeze drying with the overall purpose of targeting intermediate moisture contents in the product. Bovine serum albumin/sucrose mixtures were used as a model system to imitate high concentrated antibody formulations. First, the rate of water desorption during secondary drying at constant product temperatures (-22 °C, -10 °C, and 0 °C) was investigated for three different shelf temperatures. Residual moisture contents of sampled vials were determined by Karl Fischer titration. An equilibration step was implemented to ensure homogeneous distribution of moisture (within 1%) in all vials. The residual moisture revealed a linear relationship to the water desorption rate for different temperatures, allowing the evaluation of an anchor point from noninvasive flow rate measurements without removal of samples from the freeze dryer. The accuracy of mass flow integration from this anchor point was found to be about 0.5%. In a second step, the concept was successfully tested in a confirmation experiment. Here, good agreement was found for the initial moisture content (anchor point) and the subsequent monitoring and targeting of intermediate moisture contents. The present approach for monitoring secondary drying indicated great potential to find wider application in sterile operations on production scale in pharmaceutical freeze drying. PMID:21359604

Schneid, Stefan C; Gieseler, Henning; Kessler, William J; Luthra, Suman A; Pikal, Michael J

2011-03-01

219

High-rate pulse-train generation by phase-only filtering of an electrooptic frequency comb: Analysis and optimization  

NASA Astrophysics Data System (ADS)

We investigate the generation of high-rate optical pulse trains by spectral phase-only filtering of a frequency comb derived from an electrooptically phase-modulated continuous-wave laser. The technique is initially analyzed as a two-step filtering process. First, a fundamental pulse-train with repetition-rate equal to the modulation frequency is obtained by line-by-line phase-cancellation of the electrooptic frequency comb. Second, the temporal Talbot-effect is considered so that the output pulse repetition-rate is an integer multiple of the electrooptic modulation frequency. Nonidealities found in the fundamental train lead, in general, to multiplied trains with important degradations. We numerically analyze optimum modulation conditions for generation of output pulse trains with minimum peak-to-peak variations and/or maximum extinction level. On the other hand, a genetic algorithm is considered to numerically find optimum line-by-line phase-only filters that generate output multiplied trains with minimized degradations. Numerical simulations show that, in general, this second approach allows for improvement in the quality of the resultant multiplied trains, in terms of the uniformity degree and/or noise-level, compared with the pulse trains resulting from the Talbot-effect-based approach.

Caraquitena, José; Martí, Javier

2009-09-01

220

Initiating basal insulin therapy in type 2 diabetes: practical steps to optimize glycemic control.  

PubMed

Primary care practitioners are increasingly responsible for the management of the escalating numbers of patients with type 2 diabetes. The majority of these patients will require insulin replacement therapy as their disease progresses, because glycemic control is often unsustainable using oral antidiabetic drugs. This review explains the practicalities of initiating and optimizing basal insulin in clinical practice, emphasizing the need for regular glycated hemoglobin (A1c) monitoring to allow timely initiation of insulin when the A1c target is not met. The importance of patient education in overcoming barriers to insulin is discussed, as well as the choice of available basal insulins and the necessity to optimize basal insulin dosage by self-titration. The traditional view of insulin therapy as a last resort is challenged with the modern basal insulin analogues (insulin detemir and insulin glargine), which offer simple and effective glycemic control with a reduced risk of hypoglycemia compared with older insulin formulations such as neutral protamine Hagedorn. PMID:23953076

Philis-Tsimikas, Athena

2013-09-01

221

Near-optimal Hybrid Filtering in a Two-time-scale Model  

Microsoft Academic Search

We develop a filtering scheme for hybrid systems with the process dictating the system configuration being a finite-state Markov chain. Exploiting hierarchical structure of the underlying system, the states of the Markov chain are divided into a number of groups so that it jumps rapidly within each group and slowly among different groups. Focusing on reduction of computational complexity, the

J. W. Wang; Q. Zhang; G. Yin

2006-01-01

222

Exploration of Optimization Options for Increasing Performance of a GPU Implementation of a Three-dimensional Bilateral Filter  

SciTech Connect

This report explores using GPUs as a platform for performing high performance medical image data processing, specifically smoothing using a 3D bilateral filter, which performs anisotropic, edge-preserving smoothing. The algorithm consists of a running a specialized 3D convolution kernel over a source volume to produce an output volume. Overall, our objective is to understand what algorithmic design choices and configuration options lead to optimal performance of this algorithm on the GPU. We explore the performance impact of using different memory access patterns, of using different types of device/on-chip memories, of using strictly aligned and unaligned memory, and of varying the size/shape of thread blocks. Our results reveal optimal configuration parameters for our algorithm when executed sample 3D medical data set, and show performance gains ranging from 30x to over 200x as compared to a single-threaded CPU implementation.

Bethel, E. Wes; Bethel, E. Wes

2012-01-06

223

A COMPARISON OF MODEL BASED AND DIRECT OPTIMIZATION BASED FILTERING ALGORITHMS FOR SHEARWAVE VELOCITY RECONSTRUCTION FOR ELECTRODE VIBRATION ELASTOGRAPHY  

PubMed Central

Tissue stiffness estimation plays an important role in cancer detection and treatment. The presence of stiffer regions in healthy tissue can be used as an indicator for the possibility of pathological changes. Electrode vibration elastography involves tracking of a mechanical shear wave in tissue using radio-frequency ultrasound echoes. Based on appropriate assumptions on tissue elasticity, this approach provides a direct way of measuring tissue stiffness from shear wave velocity, and enabling visualization in the form of tissue stiffness maps. In this study, two algorithms for shear wave velocity reconstruction in an electrode vibration setup are presented. The first method models the wave arrival time data using a hidden Markov model whose hidden states are local wave velocities that are estimated using a particle filter implementation. This is compared to a direct optimization-based function fitting approach that uses sequential quadratic programming to estimate the unknown velocities and locations of interfaces. The mean shear wave velocities obtained using the two algorithms are within 10%of each other. Moreover, the Young’s modulus estimates obtained from an incompressibility assumption are within 15 kPa of those obtained from the true stiffness data obtained from mechanical testing. Based on visual inspection of the two filtering algorithms, the particle filtering method produces smoother velocity maps.

Ingle, Atul; Varghese, Tomy

2014-01-01

224

GradientShop: A gradient-domain optimization framework for image and video filtering  

Microsoft Academic Search

We present an optimization framework for exploring gradient-domain solutions for image and video processing. The proposed framework unifies many of the key ideas in the gradient-domain literature under a single optimization formulation. Our hope is that this generalized framework will allow the reader to quickly gain a general understanding of the field and contribute new ideas of their own. We

Pravin Bhat; C. Lawrence Zitnick; Michael Cohen; Brian Curless

2010-01-01

225

Optimal design of IIR digital filters with robust stability using conic-quadratic-programming updates  

Microsoft Academic Search

In this paper, minimax design of infinite-impulse-response (IIR) filters with prescribed stability margin is formulated as a conic quadratic programming (CQP) problem. CQP is known as a class of well-structured convex programming problems for which efficient interior-point solvers are available. By considering factorized denominators, the proposed formulation incorporates a set of linear constraints that are sufficient and near necessary for

Wu-Sheng Lu; Takao Hinamoto

2003-01-01

226

Optimized filtering reduces the error rate in detecting genomic variants by short-read sequencing  

Microsoft Academic Search

Distinguishing single-nucleotide variants (SNVs) from errors in whole-genome sequences remains challenging. Here we describe a set of filters, together with a freely accessible software tool, that selectively reduce error rates and thereby facilitate variant detection in data from two short-read sequencing technologies, Complete Genomics and Illumina. By sequencing the nearly identical genomes from monozygotic twins and considering shared SNVs as

Joke Reumers; Peter De Rijk; Hui Zhao; Anthony Liekens; Dominiek Smeets; John Cleary; Peter Van Loo; Maarten Van Den Bossche; Kirsten Catthoor; Bernard Sabbe; Evelyn Despierre; Ignace Vergote; Brian Hilbush; Diether Lambrechts; Jurgen Del-Favero

2011-01-01

227

Design of an Optimized Electrothermal Filter for a Temperature-to-Frequency Converter  

Microsoft Academic Search

In this paper, an analytical model of an electrothermal filter (ETF) is described. It is based on thermal impedance theory and employs several simplifying assumptions to model an ETF implemented in CMOS technology. A CMOS ETF's phase-shift has a well-defined temperature dependence, and can be utilized to build temperature-to-frequency converters (TFC). However, the resolution of such converters is limited by

S. Xia; K. A. A. Makinwa

2007-01-01

228

The matched-filter bound on optimal space-time processing in correlated fading channels  

Microsoft Academic Search

This paper presents a theoretical analysis of the matched-filter bound on N-branch space-time processing receivers in a frequency-selective correlated fading environment. The development is based on a Karhunen-Loe`ve expansion in the frequency domain. Although many other works are based on similar expansions, we present a more general analytical framework in the frequency domain covering Rayleigh and Rician fading scenarios, with

Sébastien Roy; David D. Falconer

2004-01-01

229

Optimal multiscale Kalman filter for assimilation of near-surface soil moisture into land surface models  

Microsoft Academic Search

We undertake an alternative and novel approach to assimilation of near-surface soil moisture into land surface models by means of an extension of multiscale Kalman filtering (MKF). While most data assimilation studies rely on the assumption of spatially independent near-surface soil moisture observations to attain computational tractability in large-scale problems, MKF allows us to explicitly and very efficiently model the

Laura M. Parada; Xu Liang

2004-01-01

230

A linearity and power efficient design strategy for architecture optimization of gmC biquadratic filters  

Microsoft Academic Search

To limit design time for the large range of specifications resulting from the multitude of modern communications standards, a good design strategy for analog circuits is essential, even within a given building block. This paper presents an efficient approach to design biquadratic sections for a low-pass baseband filter based on the gm-C architecture. Starting from high-level specifications, the proposed methodology

Pieter Crombez; Jan Craninckx; Michiel Steyaert

2007-01-01

231

Optimal Tuner Selection for Kalman Filter-Based Aircraft Engine Performance Estimation  

NASA Technical Reports Server (NTRS)

A linear point design methodology for minimizing the error in on-line Kalman filter-based aircraft engine performance estimation applications is presented. This technique specifically addresses the underdetermined estimation problem, where there are more unknown parameters than available sensor measurements. A systematic approach is applied to produce a model tuning parameter vector of appropriate dimension to enable estimation by a Kalman filter, while minimizing the estimation error in the parameters of interest. Tuning parameter selection is performed using a multi-variable iterative search routine which seeks to minimize the theoretical mean-squared estimation error. This paper derives theoretical Kalman filter estimation error bias and variance values at steady-state operating conditions, and presents the tuner selection routine applied to minimize these values. Results from the application of the technique to an aircraft engine simulation are presented and compared to the conventional approach of tuner selection. Experimental simulation results are found to be in agreement with theoretical predictions. The new methodology is shown to yield a significant improvement in on-line engine performance estimation accuracy

Simon, Donald L.; Garg, Sanjay

2010-01-01

232

System optimization of a field-widened Michelson interferometric spectral filter for high spectral resolution lidar  

NASA Astrophysics Data System (ADS)

High spectral resolution lidars (HSRLs) have recently shown great value in aerosol measurements form aircraft and are being called for in future space-based aerosol remote sensing applications. A quasi-monolithic field-widened, off-axis Michelson interferometer had been developed as the spectral discrimination filter for an HSRL currently under development at NASA Langley Research Center (LaRC). The Michelson filter consists of a cubic beam splitter, a solid arm and an air arm. The input light is injected at 1.5° off-axis to provide two output channels: standard Michelson output and the reflected complementary signal. Piezo packs connect the air arm mirror to the main part of the filter that allows it to be tuned within a small range. In this paper, analyses of the throughput wavephase, locking error, AR coating, and tilt angle of the interferometer are described. The transmission ratio for monochromatic light at the transmitted wavelength is used as a figure of merit for assessing each of these parameters.

Liu, Dong; Miller, Ian; Hostetler, Chris; Cook, Anthony; Hair, Johnathan

2011-06-01

233

Optimized design of four-zone phase pupil filter for nanoscale phase transition optical lithography  

NASA Astrophysics Data System (ADS)

The present paper describes a method for decreasing the pit size in optical lithography by using combination of a four-zone annular binary phase filter and the phase transition material. The binary phase filter was designed by vector diffraction theory when linearly polarized light is focused under high numerical aperture objective lens ( NA=0.95), the figures of merit produced by this filter are as follows: compared with the diffraction limited spot, Strehl ratio S is 0.254, the spot size in the short axis direction is reduced down to 77.3%, the depth of focus is elongated to 317% for the super-resolved spot,. Then a phase transition material is placed in the focal plane of the objective lens, according to the threshold effect of the material, the groove linewidth and pit size can decrease down to about 0.2?, which is about 90nm at the wavelength of 405nm. Therefore, nanoscale phase transition optical lithography is realized, and the capacity and density of the optical memory devices can be increased up to 2-3 times the blu-ray disks.

Zha, Yikun; Wei, Jingsong; Gan, Fuxi

234

OPTIMAL CONTROL OF PROJECTS BASED ON KALMAN FILTER APPROACH FOR TRACKING & FORECASTING THE PROJECT PERFORMANCE  

E-print Network

to follow the original schedule or plan, inadvertently increasing the overall project cost. Many deterministic project control methods have been proposed by various researchers for calculating optimal resource schedules considering the time-cost as well...

Bondugula, Srikant

2010-07-14

235

Determination of glucose concentrations in an aqueous matrix from NIR spectra using optimal time-domain filtering and partial least-squares regression  

Microsoft Academic Search

The authors have investigated the use of a time-domain optimal filtering method to simultaneously minimize both the baseline variation and high-frequency noise in near-infrared (NIR) spectrophotometric absorption data of glucose dissolved in a simple aqueous (deionized water) matrix. By coupling a third-order (6-pole) digital Butterworth bandpass filter with partial least-squares (PLS) regression modeling, glucose concentrations were determined for a set

Fredric M. Ham; Ivica N. Kostanic; Glenn M. Cohen; Brent R. Gooch

1997-01-01

236

Maximized gust loads for a nonlinear airplane using matched filter theory and constrained optimization  

NASA Technical Reports Server (NTRS)

This paper describes and illustrates two matched-filter-theory based schemes for obtaining maximized and time-correlated gust-loads for a nonlinear airplane. The first scheme is computationally fast because it uses a simple one-dimensional search procedure to obtain its answers. The second scheme is computationally slow because it uses a more complex multidimensional search procedure to obtain its answers, but it consistently provides slightly higher maximum loads than the first scheme. Both schemes are illustrated with numerical examples involving a nonlinear control system.

Scott, Robert C.; Perry, Boyd, III; Pototzky, Anthony S.

1991-01-01

237

Selection of optimal combinations of band-pass filters for ice detection by hyperspectral imaging.  

PubMed

Hyperspectral imaging captures rich information in spatial and spectral domains but involves high costs and complex data processing. The use of a set of optical band-pass filters (BPFs) in the acquisition of spectral images is proposed for reducing dimensionality of spectral data while maintaining target detection and/or categorization performance. A set of BPFs that could distinguish ice from surrounding water on various materials (e.g., asphalt), was designed as an example. Relatively high accuracy (90.28%) was achieved with only two BPFs, showing the potential of this approach for accurate target detection with lesser complexity than conventional methods. PMID:22274446

Nakauchi, Shigeki; Nishino, Ken; Yamashita, Takuya

2012-01-16

238

Process optimization of preparation of ZnO-porous carbon composite from spent catalysts using one step activation.  

PubMed

The process parameters of one step preparation of ZnO/Activated Carbon (AC) composite materials, from vinyl acetate synthesis spent catalyst were optimized using response surface methodology (RSM) and the central composite rotatable design (CCD). Regeneration temperature, time and flow rate of CO2 were the process variables, while the iodine number and the yield were the response variables. All the three process variables were found to significantly influence the yield of the regenerated carbon, while only the regeneration temperature and CO2 flow rate were found to significantly affect the iodine number. The optimized process conditions that maximize the yield and iodine adsorption capacity were identified to be a regeneration temperature of 950 degrees C, time of 120 min and flow rate of CO2 of 600 ml/min, with the corresponding yield and iodine number to be in excess of 50% and 1100 mg/g. The BET surface area of the regenerated composite was estimated to be 1263 m2/g, with micropore to mesopore ratio of 0.75. The pore volume was found to have increased 6 times as compared to the spent catalyst. The composite material (AC/ZnO) with high surface area and pore volume coupled with high yield augur economic feasibility of the process. EDS and XRD spectrum indicate presence of ZnO in the regenerated samples. PMID:22962730

Jin, Wen; Qu, Wen-Wen; Srinivasakannan, C; Peng, Jin-Hui; Duan, Xin-Hui; Zhang, Shi-Min

2012-08-01

239

Reduction of Common-Mode Conducted Noise Emissions in PWM Inverter-fed AC Motor Drive Systems using Optimized Passive EMI Filter  

NASA Astrophysics Data System (ADS)

Conducted electromagnetic interference (EMI) generated by PWM inverter-fed induction motor drive systems, which are currently widely used in many industrial and/or avionic applications, causes severe parasitic current problems, especially at high frequencies (HF). These restrict power electronic drive's evolution. In order to reduce or minimize these EMI problems, several techniques can be applied. In this paper, insertion of an optimized passive EMI filter is proposed. This filter is optimized by taking into account real impedances of each part of a considered AC motor drive system contrarily to commercial EMI filters designed by considering internal impedance of disturbance source and load, equal to 50?. Employing the latter EMI filter would make EMI minimization less effective. The proposed EMI filter optimization is mainly dedicated to minimize common mode (CM) currents due to its most dominant effects in this kind of system. The efficiency of the proposed optimization method using two-port network approach is deduced by comparing the minimized CM current spectra to an applied normative level (ex. DO-160D in aeronautics).

Jettanasen, C.; Ngaopitakkul, A.

2010-10-01

240

Early surgery versus optimal current step-up practice for chronic pancreatitis (ESCAPE): design and rationale of a randomized trial  

PubMed Central

Background In current practice, patients with chronic pancreatitis undergo surgical intervention in a late stage of the disease, when conservative treatment and endoscopic interventions have failed. Recent evidence suggests that surgical intervention early on in the disease benefits patients in terms of better pain control and preservation of pancreatic function. Therefore, we designed a randomized controlled trial to evaluate the benefits, risks and costs of early surgical intervention compared to the current stepwise practice for chronic pancreatitis. Methods/design The ESCAPE trial is a randomized controlled, parallel, superiority multicenter trial. Patients with chronic pancreatitis, a dilated pancreatic duct (? 5 mm) and moderate pain and/or frequent flare-ups will be registered and followed monthly as potential candidates for the trial. When a registered patient meets the randomization criteria (i.e. need for opioid analgesics) the patient will be randomized to either early surgical intervention (group A) or optimal current step-up practice (group B). An expert panel of chronic pancreatitis specialists will oversee the assessment of eligibility and ensure that allocation to either treatment arm is possible. Patients in group A will undergo pancreaticojejunostomy or a Frey-procedure in case of an enlarged pancreatic head (? 4 cm). Patients in group B will undergo a step-up practice of optimal medical treatment, if needed followed by endoscopic interventions, and if needed followed by surgery, according to predefined criteria. Primary outcome is pain assessed with the Izbicki pain score during a follow-up of 18 months. Secondary outcomes include complications, mortality, total direct and indirect costs, quality of life, pancreatic insufficiency, alternative pain scales, length of hospital admission, number of interventions and pancreatitis flare-ups. For the sample size calculation we defined a minimal clinically relevant difference in the primary endpoint as a difference of at least 15 points on the Izbicki pain score during follow-up. To detect this difference a total of 88 patients will be randomized (alpha 0.05, power 90%, drop-out 10%). Discussion The ESCAPE trial will investigate whether early surgery in chronic pancreatitis is beneficial in terms of pain relief, pancreatic function and quality of life, compared with current step-up practice. Trial registration ISRCTN: ISRCTN45877994 PMID:23506415

2013-01-01

241

Metrics For Comparing Plasma Mass Filters  

SciTech Connect

High-throughput mass separation of nuclear waste may be useful for optimal storage, disposal, or environmental remediation. The most dangerous part of nuclear waste is the fission product, which produces most of the heat and medium-term radiation. Plasmas are well-suited to separating nuclear waste because they can separate many different species in a single step. A number of plasma devices have been designed for such mass separation, but there has been no standardized comparison between these devices. We define a standard metric, the separative power per unit volume, and derive it for three different plasma mass filters: the plasma centrifuge, Ohkawa filter, and the magnetic centrifugal mass filter. __________________________________________________

Abraham J. Fetterman and Nathaniel J. Fisch

2012-08-15

242

An optimized DSP implementation of adaptive filtering and ICA for motion artifact reduction in ambulatory ECG monitoring.  

PubMed

Noise from motion artifacts is currently one of the main challenges in the field of ambulatory ECG recording. To address this problem, we propose the use of two different approaches. First, an adaptive filter with electrode-skin impedance as a reference signal is described. Secondly, a multi-channel ECG algorithm based on Independent Component Analysis is introduced. Both algorithms have been designed and further optimized for real-time work embedded in a dedicated Digital Signal Processor. We show that both algorithms improve the performance of a beat detection algorithm when applied in high noise conditions. In addition, an efficient way of choosing this methods is suggested with the aim of reduce the overall total system power consumption. PMID:23367417

Berset, Torfinn; Geng, Di; Romero, Iñaki

2012-01-01

243

Particle swarm optimization-based approach for optical finite impulse response filter design  

E-print Network

algorithms such as a genetic algorithm have been attempted feasibly but the genetic operators by the optimization algorithm. This structure determines the output that if N plates are concerned, there will be N 1 than some previous optimiz- The authors are with the Optical Engineering Department, State Key

Wu, Shin-Tson

244

Medical image processing using novel wavelet filters based on atomic functions: optimal medical image compression.  

PubMed

The analysis of different Wavelets including novel Wavelet families based on atomic functions are presented, especially for ultrasound (US) and mammography (MG) images compression. This way we are able to determine with what type of filters Wavelet works better in compression of such images. Key properties: Frequency response, approximation order, projection cosine, and Riesz bounds were determined and compared for the classic Wavelets W9/7 used in standard JPEG2000, Daubechies8, Symlet8, as well as for the complex Kravchenko-Rvachev Wavelets ?(t) based on the atomic functions up(t),? fup (2)(t), and eup(t). The comparison results show significantly better performance of novel Wavelets that is justified by experiments and in study of key properties. PMID:21431590

Landin, Cristina Juarez; Reyes, Magally Martinez; Martin, Anabelem Soberanes; Rosas, Rosa Maria Valdovinos; Ramirez, Jose Luis Sanchez; Ponomaryov, Volodymyr; Soto, Maria Dolores Torres

2011-01-01

245

Optimal spatial filtering and transfer function for SAR ocean wave spectra  

NASA Astrophysics Data System (ADS)

The impulse response of the SAR system is not a delta function and the spectra represent the product of the underlying image spectrum with the transform of the impulse response which must be removed. A digitally computed spectrum of SEASAT imagery of the Atlantic Ocean east of Cape Hatteras was smoothed with a 5 x 5 convolution filter and the trend was sampled in a direction normal to the predominant wave direction. This yielded a transform of a noise-like process. The smoothed value of this trend is the transform of the impulse response. This trend is fit with either a second- or fourth-order polynomial which is then used to correct the entire spectrum. A 16 x 16 smoothing of the spectrum shows the presence of two distinct swells. Correction of the effects of speckle is effected by the subtraction of a bias from the spectrum.

Beal, R. C.; Tilley, D. G.

1981-06-01

246

Optimal spatial filtering and transfer function for SAR ocean wave spectra  

NASA Technical Reports Server (NTRS)

The impulse response of the SAR system is not a delta function and the spectra represent the product of the underlying image spectrum with the transform of the impulse response which must be removed. A digitally computed spectrum of SEASAT imagery of the Atlantic Ocean east of Cape Hatteras was smoothed with a 5 x 5 convolution filter and the trend was sampled in a direction normal to the predominant wave direction. This yielded a transform of a noise-like process. The smoothed value of this trend is the transform of the impulse response. This trend is fit with either a second- or fourth-order polynomial which is then used to correct the entire spectrum. A 16 x 16 smoothing of the spectrum shows the presence of two distinct swells. Correction of the effects of speckle is effected by the subtraction of a bias from the spectrum.

Beal, R. C.; Tilley, D. G.

1981-01-01

247

Optimal spatial filtering for brain oscillatory activity using the Relevance Vector Machine.  

PubMed

Over the past decade, various techniques have been proposed for localization of cerebral sources of oscillatory activity on the basis of magnetoencephalography (MEG) or electroencephalography recordings. Beamformers in the frequency domain, in particular, have proved useful in this endeavor. However, the localization accuracy and efficacy of such spatial filters can be markedly limited by bias from correlation between cerebral sources and short duration of source activity, both essential issues in the localization of brain data. Here, we evaluate a method for frequency-domain localization of oscillatory neural activity based on the relevance vector machine (RVM). RVM is a Bayesian algorithm for learning sparse models from possibly overcomplete data sets. The performance of our frequency-domain RVM method (fdRVM) was compared with that of dynamic imaging of coherent sources (DICS), a frequency-domain spatial filter that employs a minimum variance adaptive beamformer (MVAB) approach. The methods were tested both on simulated and real data. Two types of simulated MEG data sets were generated, one with continuous source activity and the other with transiently active sources. The real data sets were from slow finger movements and resting state. Results from simulations show comparable performance for DICS and fdRVM at high signal-to-noise ratios and low correlation. At low SNR or in conditions of high correlation between sources, fdRVM performs markedly better. fdRVM was successful on real data as well, indicating salient focal activations in the sensorimotor area. The resulting high spatial resolution of fdRVM and its sensitivity to low-SNR transient signals could be particularly beneficial when mapping event-related changes of oscillatory activity. PMID:23729235

Belardinelli, P; Jalava, A; Gross, J; Kujala, J; Salmelin, R

2013-11-01

248

Shuttle filter study. Volume 1: Characterization and optimization of filtration devices  

NASA Technical Reports Server (NTRS)

A program to develop a new technology base for filtration equipment and comprehensive fluid particulate contamination management techniques was conducted. The study has application to the systems used in the space shuttle and space station projects. The scope of the program is as follows: (1) characterization and optimization of filtration devices, (2) characterization of contaminant generation and contaminant sensitivity at the component level, and (3) development of a comprehensive particulate contamination management plane for space shuttle fluid systems.

1974-01-01

249

FIR filter optimization using bit-edge equalization in high-speed backplane data transmission  

Microsoft Academic Search

A unique bit-edge equalization (BEE) method for mitigating intersymbol interference (ISI) in high-speed backplane applications is presented. Using a least-mean-square (LMS) adaptive algorithm as a receiver (RX) error convergence engine, the proposed BEE method aims to optimize the bit-edge amplitudes by equalizing only the edges of data bits with an adjustment of the sampling points where the error information is

Lei Zhang; Tadeusz Kwasniewski

2009-01-01

250

Heterologous expression and optimized one-step separation of levansucrase via elastin-like polypeptides tagging system.  

PubMed

Elastin-like polypeptides (ELPs) undergo a reversible inverse phase transition upon a change in temperature. This thermally triggered phase transition allows for a simple and rapid means of purifying a fusion protein. Recovery of ELPs-tagged fusion protein was easily achieved by aggregation, triggered either by raising temperature or by adding salt. In this study, levansucrase has been used as a model enzyme in the development of a simple one-step purification method using ELPs. The levansucrase gene cloned from Pseudomonas aurantiaca S-4380 was tagged with various sizes of ELPs to functionally express and optimize the purification of levansucrase. One of two ELPs, ELP[V-20] or ELP[V-40], was fused at the C-terminus of the levansucrase gene. A levansucrase-ELP fusion protein was expressed in Escherichia coli DH5alpha at 37 degrees C for 18 h. The molecular masses of levansucrase-ELP[V-20] and levansucrase-ELP[V-40] were determined as 56 kDa and 65 kDa, respectively. The phase transition of levansucrase-ELP[V-20] occurred at 20 degrees C in 50 mM Tris-Cl (pH 8) buffer with 3 M NaCl added, whereas the phase transition temperature (Tt) of levansucrase-ELP[V-40] was 17 degrees C with 2 M NaCl. Levansucrase was successfully purified using the phase transition characteristics of ELPs, with a recovery yield of higher than 80%, as verified by SDS-PAGE. The specific activity was measured spectrophotometrically to be 173 U/mg and 171 U/mg for levansucrase-ELP[V-20] and levansucrase-ELP[V-40], respectively, implying that the ELP-tagging system provides an efficient one-step separation method for protein purification. PMID:18092457

Kang, Hye-Jin; Kim, Jin-Hee; Chang, Woo-Jin; Kim, Eung-Soo; Koo, Yoon-Mo

2007-11-01

251

Optimized multiple-quantum filter for robust selective excitation of metabolite signals.  

PubMed

The selective excitation of metabolite signals in vivo requires the use of specially adapted pulse techniques, in particular when the signals are weak and the resonances overlap with those of unwanted molecules. Several pulse sequences have been proposed for this spectral editing task. However, their performance is strongly degraded by unavoidable experimental imperfections. Here, we show that optimal control theory can be used to generate pulses and sequences that perform almost ideally over a range of rf field strengths and frequency offsets that can be chosen according to the specifics of the spectrometer or scanner being used. We demonstrate this scheme by applying it to lactate editing. In addition to the robust excitation, we also have designed the pulses to minimize the signal of unwanted molecular species. PMID:24705532

Holbach, Mirjam; Lambert, Jörg; Suter, Dieter

2014-06-01

252

Moment tensor solutions estimated using optimal filter theory for 51 selected earthquakes, 1980-1984  

USGS Publications Warehouse

The 51 global events that occurred from January 1980 to March 1984, which were chosen by the convenors of the Symposium on Seismological Theory and Practice, have been analyzed using a moment tensor inversion algorithm (Sipkin). Many of the events were routinely analyzed as part of the National Earthquake Information Center's (NEIC) efforts to publish moment tensor and first-motion fault-plane solutions for all moderate- to large-sized (mb>5.7) earthquakes. In routine use only long-period P-waves are used and the source-time function is constrained to be a step-function at the source (??-function in the far-field). Four of the events were of special interest, and long-period P, SH-wave solutions were obtained. For three of these events, an unconstrained inversion was performed. The resulting time-dependent solutions indicated that, for many cases, departures of the solutions from pure double-couples are caused by source complexity that has not been adequately modeled. These solutions also indicate that source complexity of moderate-sized events can be determined from long-period data. Finally, for one of the events of special interest, an inversion of the broadband P-waveforms was also performed, demonstrating the potential for using broadband waveform data in inversion procedures. ?? 1987.

Sipkin, S.A.

1987-01-01

253

Adaptive two step method and its application in the interception of hypersonic random maneuvering target  

Microsoft Academic Search

The two step filter is suitable for the optimal estimation problem of systems with linear state function and nonlinear measurement function. This paper considered the problem of the interception of hypersonic random maneuvering target and for the special math model discussed, adaptive two step method was integrated with Fast MMAE method in order to detect and identify target maneuvering while

Wang Yuzhe; Shi Xiaoping

2010-01-01

254

The Mauna Kea Observatories Near-Infrared Filter Set. I: Defining Optimal 1-5 $?$m Bandpasses  

E-print Network

A new MKO-NIR infrared filter set is described, including techniques and considerations given to designing a new set of bandpasses that are useful at both mid- and high-altitude sites. These filters offer improved photometric linearity and in many cases reduced background, as well as preserve good throughput within the JHKLM atmospheric windows. MKO-NIR filters have already been deployed with a number of instruments around the world as part of a filter consortium purchase to reduce the unit cost of filters. Through this effort we hope to establish, for the first time, a single standard set of infrared fitlers at as many observatories as possible.

D. A. Simons; A. T. Tokunaga

2001-10-28

255

Model-Based Control of a Nonlinear Aircraft Engine Simulation using an Optimal Tuner Kalman Filter Approach  

NASA Technical Reports Server (NTRS)

This paper covers the development of a model-based engine control (MBEC) methodology featuring a self tuning on-board model applied to an aircraft turbofan engine simulation. Here, the Commercial Modular Aero-Propulsion System Simulation 40,000 (CMAPSS40k) serves as the MBEC application engine. CMAPSS40k is capable of modeling realistic engine performance, allowing for a verification of the MBEC over a wide range of operating points. The on-board model is a piece-wise linear model derived from CMAPSS40k and updated using an optimal tuner Kalman Filter (OTKF) estimation routine, which enables the on-board model to self-tune to account for engine performance variations. The focus here is on developing a methodology for MBEC with direct control of estimated parameters of interest such as thrust and stall margins. Investigations using the MBEC to provide a stall margin limit for the controller protection logic are presented that could provide benefits over a simple acceleration schedule that is currently used in traditional engine control architectures.

Connolly, Joseph W.; Csank, Jeffrey Thomas; Chicatelli, Amy; Kilver, Jacob

2013-01-01

256

Ultralong, small-diameter TiOTiO? nanotubes achieved by an optimized two-step anodization for efficient dye-sensitized solar cells.  

PubMed

An optimized two-step anodization is developed to fabricate ultralong, small-diameter TiO2 nanotubes, that is, with tube length of up to 31 ?m and pore diameter of about 35 nm in this work. This overcomes the length limitation of small diameter tubes that usually presents in conventional one-step anodization. The small tubes with lengths of 23 ?m yield a conversion efficiency of 5.02% in dye-sensitized solar cells under nonoptimized conditions. PMID:24443896

Wang, Xiaoyan; Sun, Lidong; Zhang, Sam; Wang, Xiu

2014-02-12

257

The Mauna Kea Observatories Near-Infrared Filter Set. I. Defining Optimal 1-5 Micron Bandpasses  

NASA Astrophysics Data System (ADS)

A new Mauna Kea Observatories near-infrared (MKO-NIR) filter set is described, including techniques and considerations given to designing a new set of bandpasses that are useful at both mid- and high-altitude sites. These filters offer improved photometric linearity and in many cases reduced background, as well as preserving good throughput within the JHKLM atmospheric windows. MKO-NIR filters have already been deployed within a number of instruments around the world as part of a filter consortium purchase to reduce the unit cost of filters. Through this effort we hope to establish, for the first time, a single standard set of infrared filters at as many observatories as possible.

Simons, D. A.; Tokunaga, A.

2002-02-01

258

The Mauna Kea Observatories Near-Infrared Filter Set. I: Defining Optimal 1-5 $\\\\mu$m Bandpasses  

Microsoft Academic Search

A new MKO-NIR infrared filter set is described, including techniques and\\u000aconsiderations given to designing a new set of bandpasses that are useful at\\u000aboth mid- and high-altitude sites. These filters offer improved photometric\\u000alinearity and in many cases reduced background, as well as preserve good\\u000athroughput within the JHKLM atmospheric windows. MKO-NIR filters have already\\u000abeen deployed with a

D. A. Simons; A. T. Tokunaga

2001-01-01

259

The Mauna Kea Observatories Near-Infrared Filter Set. I. Defining Optimal 1-5 Micron Bandpasses  

Microsoft Academic Search

A new Mauna Kea Observatories near-infrared (MKO-NIR) filter set is described, including techniques and considerations given to designing a new set of bandpasses that are useful at both mid- and high-altitude sites. These filters offer improved photometric linearity and in many cases reduced background, as well as preserving good throughput within the JHKLM atmospheric windows. MKO-NIR filters have already been

D. A. Simons; A. Tokunaga

2002-01-01

260

Nonlinear Attitude Filtering Methods  

NASA Technical Reports Server (NTRS)

This paper provides a survey of modern nonlinear filtering methods for attitude estimation. Early applications relied mostly on the extended Kalman filter for attitude estimation. Since these applications, several new approaches have been developed that have proven to be superior to the extended Kalman filter. Several of these approaches maintain the basic structure of the extended Kalman filter, but employ various modifications in order to provide better convergence or improve other performance characteristics. Examples of such approaches include: filter QUEST, extended QUEST, the super-iterated extended Kalman filter, the interlaced extended Kalman filter, and the second-order Kalman filter. Filters that propagate and update a discrete set of sigma points rather than using linearized equations for the mean and covariance are also reviewed. A two-step approach is discussed with a first-step state that linearizes the measurement model and an iterative second step to recover the desired attitude states. These approaches are all based on the Gaussian assumption that the probability density function is adequately specified by its mean and covariance. Other approaches that do not require this assumption are reviewed, including particle filters and a Bayesian filter based on a non-Gaussian, finite-parameter probability density function on SO(3). Finally, the predictive filter, nonlinear observers and adaptive approaches are shown. The strengths and weaknesses of the various approaches are discussed.

Markley, F. Landis; Crassidis, John L.; Cheng, Yang

2005-01-01

261

Two-step biodiesel production from Calophyllum inophyllum oil: optimization of modified ?-zeolite catalyzed pre-treatment.  

PubMed

In this study, a two-step process was developed to produce biodiesel from Calophyllum inophyllum oil. Pre-treatment with phosphoric acid modified ?-zeolite in acid catalyzed esterification process preceded by transesterification which was done using conventional alkali catalyst potassium hydroxide (KOH). The objective of this study is to investigate the relationship between the reaction temperatures, reaction time and methanol to oil molar ratio in the pre-treatment step. Central Composite Design (CCD) and Response Surface Methodology (RSM) were utilized to determine the best operating condition for the pre-treatment step. Biodiesel produced by this process was tested for its fuel properties. PMID:20833536

SathyaSelvabala, Vasanthakumar; Selvaraj, Dinesh Kirupha; Kalimuthu, Jalagandeeswaran; Periyaraman, Premkumar Manickam; Subramanian, Sivanesan

2011-01-01

262

Variational Particle Filter for Imperfect Models  

NASA Astrophysics Data System (ADS)

Whereas classical data processing techniques work with perfect models geophysical sciences have to deal with imperfect models with spatially structured errors. For the perfect model cases, in terms of Mean-Field Markovian processes, the optimal filter is known: the Kalman estimator is the answer to the linearGaussian problem and in the general case Particle approximations are the empirical solutions to the optimal estimator. We will present another way to decompose the Bayes rule, using an one step ahead observation. This method is well adapted to the strong nonlinear or chaotic systems. Then, in order to deal with imperfect model, we suggest in this presentation to learn the (large scale) model errors using a variational correction before the resampling step of the non-linear filtering. This procedure replace the a-priori Markovian transition by a kernel conditioned to the observations. This supplementary step may be read as the use of variational particles approximation. For the numerical applications, we have chosen to show the impact of our method, first on a simple marked Poisson process with Gaussian observation noises (the time-exponential jumps are considered as model errors) and then on a 2D shallow water experiment in a closed basin, with some falling droplets as model errors.; Marked Poisson process with Gaussian observation noise filtered by four methods: classical Kalman filter, genetic particle filter, trajectorial particle filter and Kalman-particle filter. All use only 10 particles. ; 2D Shallow Water simulation with droplets errors. Results of a classical 3DVAR and of our VarPF (10 particles).

Baehr, C.

2012-12-01

263

Combined digital filtering of harmonic content of phase-shift keyed signals in the problem of estimation of the time delay  

NASA Astrophysics Data System (ADS)

We propose a two-step method for digital filtering of phase-shift keyed signals filtering in the problem of determination of the time delay during the multichannel propagation. The first step is realized as an information-optimal linear filter with complex coefficients, while the second step, as a quadratic filter based on the minimum-variance criterion. The e.ciency of the proposed method is demonstrated for short PSK signals with various carrier frequencies against the background of additive and multiplicative noise. The developed algorithm can easily be implemented in real time on the basis of a digital signal processor.

Loginov, A. A.; Morozov, O. A.; Soldatov, E. A.; Khmelev, S. L.

2007-03-01

264

Near-Optimal Deterministic Filtering on the Unit Circle Paul Coote, Jochen Trumpf, Robert Mahony, Jan C. Willems  

E-print Network

and references. The paradigmatic example is the Kalman filter for linear systems that produces the maximum estimate is updated. Unfortunately, the desirable characteristics of linear stochastic filters -- primarily the property that the parametric space of Gaussian random variables is closed under transformations by linear

265

An NLMS algorithm with optimized preparatory step-size parameters for SQUID-based MCG data processing  

NASA Astrophysics Data System (ADS)

We present a new least-mean-square algorithm of adaptive filtering to improve the signal to noise ratio for magnetocardiography data collected with high-temperature SQUID-based magnetometers. By frequently adjusting the adaptive parameter ? to systematic optimum values in the course of the programmed procedure, the convergence is accelerated with a highest speed and the minimum steady-state error is obtained simultaneously. This algorithm may be applied to eliminate other non-steady relevant noises as well.

Li, Zhuo; Chen, Geng-Hua; Zhang, Li-Hua; Yang, Qian-Sheng; Feng, Ji

2006-02-01

266

Study on Optimization Method of Quantization Step and the Image Quality Evaluation for Medical Ultrasonic Echo Image Compression by Wavelet Transform  

NASA Astrophysics Data System (ADS)

In this paper, we investigate optimized quantization method in JPEG2000 application for medical ultrasonic echo images. JPEG2000 has been issued as the new standard for image compression technique, which is based on Wavelet Transform (WT) and JPEG2000 incorporated into DICOM (Digital Imaging and Communications in Medicine). There are two quantization methods. One is the scalar derived quantization (SDQ), which is usually used in standard JPEG2000. The other is the scalar expounded quantization (SEQ), which can be optimized by user. Therefore, this paper is an optimization of quantization step, which is determined by Genetic Algorithm (GA). Then, the results are compared with SDQ and SEQ determined by arithmetic average method. The purpose of this paper is to improve image quality and compression ratio for medical ultrasonic echo images. The image quality is evaluated by objective assessment, PSNR (Peak Signal to Noise Ratio) and subjective assessment is evaluated by ultrasonographers from Tokai University Hospital and Tokai University Hachioji Hospital. The results show that SEQ determined by GA provides better image quality than SDQ and SEQ determined by arithmetic average method. Additionally, three optimization methods of quantization step apply to thin wire target image for analysis of point spread function.

Khieovongphachanh, Vimontha; Hamamoto, Kazuhiko; Kondo, Shozo

267

Proton polarization above 70% by DNP using photo-excited triplet states, a first step towards a broadband neutron spin filter  

NASA Astrophysics Data System (ADS)

The use of polarized protons as neutron spin filter is an attractive alternative to the well established neutron polarization techniques, as the large, spin-dependent neutron scattering cross-section for protons is useful up to the sub-MeV region. Employing optically excited triplet states for the dynamic nuclear polarization (DNP) of the protons relieves the stringent requirements of classical DNP schemes, i.e low temperatures and strong magnetic fields, making technically simpler systems with open geometries possible. Using triplet DNP a record polarization of 71% has been achieved in a pentacene doped naphthalene single crystal at a field of 0.36 T using a simple helium flow cryostat for cooling. Furthermore, by placing the polarized crystal in a neutron optics focus and de-focus scheme, the actual sample cross-section could be increased by a factor 35 corresponding to an effective spin filter cross-section of 18×18 mm2.

Eichhorn, T. R.; Niketic, N.; van den Brandt, B.; Filges, U.; Panzner, T.; Rantsiou, E.; Wenckebach, W. Th.; Hautle, P.

2014-08-01

268

Multilayer filter design with high K materials  

NASA Astrophysics Data System (ADS)

A novel approach to filter design is presented. A high-K multilayer coupled line filter is designed for optimal performance within a dielectric resonator of rectangular cross section. The multilayer filter is shown to have a performance comparable to its planar counterpart as well as the Lange coupler while maintaining the design advantages that come with the multilayer approach to filter design such as increased flexibility in managing parameter constraints. The performance of the rectangular cross sectioned resonator in terms of modal response and resonant frequency has been evaluated through mathematical derivation and simulation. The reader will find the step by step process to designing the resonant structure as well as a MATLAB script that will graphically display the effect changing various parameters may have on resonator size to assist in the design analysis. The resonator has been designed to provide a finite package in terms of space and performance so that it may house the multilayer filter on a printed circuit board for ease of system implementation. The proposed design with analysis will prove useful for all multilayer coupled line filter types that may take advantage of the uniform environment provided by the finite packaging of the dielectric resonator. As with any microwave system, considerable effort must be put forth to maintain signal integrity throughout the delivery process from the signal input to reception at the output. As a result a large amount of effort and research has gone into answering the question of how to efficiently feed both a dielectric resonator filter of rectangular cross section as well as a coupled line filter that would be embedded within the resonators confines. Several methods for feeding have been explored and reported on. Of the feeding methods reported on the most feasible design includes a unique microstrip delivery to the embedded multilayer filter as pictured here.* *Please refer to dissertation for diagram.

Curtis, Nathaniel, II

269

The University of Arizona College of Medicine Optimal Aging Program: Stepping in the Shadows of Successful Aging  

ERIC Educational Resources Information Center

The Optimal Aging Program (OAP) at the University of Arizona, College of Medicine is a longitudinal mentoring program that pairs students with older adults who are considered to be aging "successfully." This credit-bearing elective was initially established in 2001 through a grant from the John A. Hartford Foundation, and aims to expand the…

Sikora, Stephanie

2006-01-01

270

An optimized and low-cost FPGA-based DNA sequence alignment--a step towards personal genomics.  

PubMed

DNA sequence alignment is a cardinal process in computational biology but also is much expensive computationally when performing through traditional computational platforms like CPU. Of many off the shelf platforms explored for speeding up the computation process, FPGA stands as the best candidate due to its performance per dollar spent and performance per watt. These two advantages make FPGA as the most appropriate choice for realizing the aim of personal genomics. The previous implementation of DNA sequence alignment did not take into consideration the price of the device on which optimization was performed. This paper presents optimization over previous FPGA implementation that increases the overall speed-up achieved as well as the price incurred by the platform that was optimized. The optimizations are (1) The array of processing elements is made to run on change in input value and not on clock, so eliminating the need for tight clock synchronization, (2) the implementation is unrestrained by the size of the sequences to be aligned, (3) the waiting time required for the sequences to load to FPGA is reduced to the minimum possible and (4) an efficient method is devised to store the output matrix that make possible to save the diagonal elements to be used in next pass, in parallel with the computation of output matrix. Implemented on Spartan3 FPGA, this implementation achieved 20 times performance improvement in terms of CUPS over GPP implementation. PMID:24110283

Shah, Hurmat Ali; Hasan, Laiq; Ahmad, Nasir

2013-01-01

271

Smoothing filter for digital to analog conversion  

Microsoft Academic Search

An electronic filter comprised of three active filter sections to smooth the stepped signal from a digital to analog converter is described. The first section has a noninverting low pass filter transfer function, and the second has an inverting transfer function designed to pass a narrow frequency band centered at the step frequency of the stepped output signal with sharp

C. A. Wagner

1981-01-01

272

Development of an optimal automatic control law and filter algorithm for steep glideslope capture and glideslope tracking  

NASA Technical Reports Server (NTRS)

A digital automatic control law to capture a steep glideslope and track the glideslope to a specified altitude is developed for the longitudinal/vertical dynamics of a CTOL aircraft using modern estimation and control techniques. The control law uses a constant gain Kalman filter to process guidance information from the microwave landing system, and acceleration from body mounted accelerometer data. The filter outputs navigation data and wind velocity estimates which are used in controlling the aircraft. Results from a digital simulation of the aircraft dynamics and the control law are presented for various wind conditions.

Halyo, N.

1976-01-01

273

Development and implementation of optimal filtering in a Virtex FPGA for the upgrade of the ATLAS LAr calorimeter readout  

NASA Astrophysics Data System (ADS)

In the context of upgraded read-out systems for the Liquid-Argon Calorimeters of the ATLAS detector, modified front-end, back-end and trigger electronics are foreseen for operation in the high-luminosity phase of the LHC. Accuracy and efficiency of the energy measurement and reliability of pile-up suppression are substantial when processing the detector raw-data in real-time. Several digital filter algorithms are investigated for their performance to extract energies from incoming detector signals and for the needs of the future trigger system. The implementation of fast, resource economizing, parameter driven filter algorithms in a modern Virtex FPGA is presented.

Stärz, S.

2012-12-01

274

Second-Order-Optimal Filters on Lie groups Alessandro Saccon, Jochen Trumpf, Robert Mahony, A. Pedro Aguiar  

E-print Network

by Mortensen [1] and further developed by Hijab [2]. It is known that the minimum energy-filter for linear that can be used for pose estimation, a problem with state space SE(3), the special Euclidean group. Their approach uses an embedding of SE(3) in a matrix vector space and is hence not intrinsic with respect

Trumpf, Jochen

275

Kalman filter outputs for inclusion in video-stream metadata: accounting for the temporal correlation of errors for optimal target extraction  

NASA Astrophysics Data System (ADS)

A video-stream associated with an Unmanned System or Full Motion Video can support the extraction of ground coordinates of a target of interest. The sensor metadata associated with the video-stream includes a time series of estimates of sensor position and attitude, required for down-stream single frame or multi-frame ground point extraction, such as stereo extraction using two frames in the video-stream that are separated in both time and imaging geometry. The sensor metadata may also include a corresponding time history of sensor position and attitude estimate accuracy (error covariance). This is required for optimal down-stream target extraction as well as corresponding reliable predictions of extraction accuracy. However, for multi-frame extraction, this is only a necessary condition. The temporal correlation of estimate errors (error cross-covariance) between an arbitrary pair of video frames is also required. When the estimates of sensor position and attitude are from a Kalman filter, as typically the case, the corresponding error covariances are automatically computed and available. However, the cross-covariances are not. This paper presents an efficient method for their exact representation in the metadata using additional, easily computed, data from the Kalman filter. The paper also presents an optimal weighted least squares extraction algorithm that correctly accounts for the temporal correlation, given the additional metadata. Simulation-based examples are presented that show the importance of correctly accounting for temporal correlation in multi-frame extraction algorithms.

Dolloff, J. T.

2012-06-01

276

Pretreatment based on two-step steam explosion combined with an intermediate separation of fiber cells--optimization of fermentation of corn straw hydrolysates.  

PubMed

Pretreatment is necessary for lignocellulose to achieve a highly efficient enzymatic hydrolysis and fermentation. However, coincident with pretreatment, compounds inhibiting microorganism growth are formed. Some tissues or cells, such as thin-walled cells that easily hydrolyze, will be excessively degraded because of the structural heterogeneity of lignocellulose, and some inhibitors will be generated under the same pretreatment conditions. Results showed, compared with one-step steam explosion (1.2 MPa/8 min), two-step steam explosion with an intermediate separation of fiber cells (ISFC) (1.1 Mpa/4 min-ISFC-1.2 MPa/4 min) can increase enzymatic hydrolyzation by 12.82%, reduce inhibitor conversion by 33%, and increase fermentation product (2,3-butanediol) conversion by 209%. Thus, the two-step steam explosion with ISFC process is proposed to optimize the hydrolysis process of lignocellulose by modifying the raw material from the origin. This novel process reduces the inhibitor content, promotes the biotransformation of lignocellulose, and simplifies the process of excluding the detoxification unit operation. PMID:22858472

Zhang, Yuzhen; Fu, Xiaoguo; Chen, Hongzhang

2012-10-01

277

A Kalman filter for a two-dimensional shallow-water model  

NASA Technical Reports Server (NTRS)

A two-dimensional Kalman filter is described for data assimilation for making weather forecasts. The filter is regarded as superior to the optimal interpolation method because the filter determines the forecast error covariance matrix exactly instead of using an approximation. A generalized time step is defined which includes expressions for one time step of the forecast model, the error covariance matrix, the gain matrix, and the evolution of the covariance matrix. Subsequent time steps are achieved by quantifying the forecast variables or employing a linear extrapolation from a current variable set, assuming the forecast dynamics are linear. Calculations for the evolution of the error covariance matrix are banded, i.e., are performed only with the elements significantly different from zero. Experimental results are provided from an application of the filter to a shallow-water simulation covering a 6000 x 6000 km grid.

Parrish, D. F.; Cohn, S. E.

1985-01-01

278

An IIR median hybrid filter  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

279

The Diffusion Kernel Filter  

NASA Astrophysics Data System (ADS)

A particle filter method is presented for the discrete-time filtering problem with nonlinear Itô stochastic ordinary differential equations (SODE) with additive noise supposed to be analytically integrable as a function of the underlying vector-Wiener process and time. The Diffusion Kernel Filter is arrived at by a parametrization of small noise-driven state fluctuations within branches of prediction and a local use of this parametrization in the Bootstrap Filter. The method applies for small noise and short prediction steps. With explicit numerical integrators, the operations count in the Diffusion Kernel Filter is shown to be smaller than in the Bootstrap Filter whenever the initial state for the prediction step has sufficiently few moments. The established parametrization is a dual-formula for the analysis of sensitivity to gaussian-initial perturbations and the analysis of sensitivity to noise-perturbations, in deterministic models, showing in particular how the stability of a deterministic dynamics is modeled by noise on short times and how the diffusion matrix of an SODE should be modeled (i.e. defined) for a gaussian-initial deterministic problem to be cast into an SODE problem. From it, a novel definition of prediction may be proposed that coincides with the deterministic path within the branch of prediction whose information entropy at the end of the prediction step is closest to the average information entropy over all branches. Tests are made with the Lorenz-63 equations, showing good results both for the filter and the definition of prediction.

Krause, Paul

2009-01-01

280

Estimation and filter stability of stochastic delay systems  

NASA Technical Reports Server (NTRS)

Linear and nonlinear filtering for stochastic delay systems are studied. A representation theorem for conditional moment functionals is obtained, which, in turn, is used to derive stochastic differential equations describing the optimal linear or nonlinear filter. A complete characterization of the optimal filter is given for linear systems with Gaussian noise. Stability of the optimal filter is studied in the case where there are no delays in the observations. Using the duality between linear filtering and control, asymptotic stability of the optimal filter is proved. Finally, the cascade of the optimal filter and the deterministic optimal quadratic control system is shown to be asymptotically stable as well.

Kwong, R. H.; Willsky, A. S.

1978-01-01

281

Optimal Placement of Pressure Monitoring Wells for CO2 Leakage using Kalman filters and a Genetic Algorithm  

NASA Astrophysics Data System (ADS)

One option for monitoring CO2 injection is through pressure measurements made in formations overlying the injection formation. If pressure perturbations due to leakage can be separated from natural background variability, then this can be a viable technology to monitor for CO2 or brine leakage. Two key questions are how many monitoring wells are needed to detect a leakage event, and where those wells should be placed. In this study we present a methodology that uses a combination of a Kalman filter algorithm, a physically based analytical model that solves for pressure propagation across old/abandoned leaky wells in a multi-formation system, and a multi-objective genetic algorithm, to answer these two questions. The Kalman filter is used to explore the covariance reduction based on possible well positions. The physically based model is used to simulate, in a Monte Carlo scheme, a wide range of possible leakage scenarios where the main unknown is the permeability of the old/abandoned leaky wells. The multi-objective genetic algorithm is the Non-dominated Sorting Genetic Algorithm (NSGA-II). The models are combined to address the following three objectives: (1) The minimization of the total variance of the pressure field, (2) the minimization of the number of wells needed to detect a leakage event, and (3) the identification and subsequent elimination of detected leakage events that are considered to be "not harmful, where "harmful" refers to an event in which the pressure change in the monitored formation is not large enough to induce leakage into the deepest potable water aquifer. The methodology is applied to a synthetic case study, which serves to prove the applicability of the methods and to gather insights on the strengths and weaknesses of using pressure monitoring wells to detect a CO2 leakage event.

Nogues, J. P.; Nordbotten, J. M.; Celia, M. A.

2013-05-01

282

Implementation of Kalman Filter with Python Language  

Microsoft Academic Search

In this paper, we investigate the implementation of a Python code for a Kalman Filter using the Numpy package. A Kalman Filtering is carried out in two steps: Prediction and Update. Each step is investigated an d coded as a function with matrix input and output. These different functions are exp lained and an example of a Kalman Filter application

Mohamed LAARAIEDH

283

Refinement and generalization of the extension method of covariance matrix inversion by regularization for spectral filtering optimization  

NASA Astrophysics Data System (ADS)

Many spectral signature detection algorithms depend on numerically inverting covariance matrices. Hyperspectral data rarely span the full band space because of factors such as sensor noise, numerical round-off, sparse sampling, and band correlation inherent in the data or introduced by data processing. Processing the full order of the covariance matrix without regard to its useful rank leads to reduced detection performance. It was previously shown that the performance of inverse-covariance based detection algorithms can be improved by regularizing the covariance matrix inversion through extension of an optimally chosen eigenvalue. The extension method provides a robust way to optimize signal to clutter ratio (SCR) on data collected with a detector of uniform gain. The method of trusted eigenvalue extension has now been applied to data collected with a sensor with multiple gain regions. Multiple gain regions are used on wide spectral range sensors such as HYDICE and complicate the inversion of the covariance matrix over the full range of spectral bands. Further optimization of the trusted eigenvalue is presented and compared against traditional regularization methods. Since the extension method is particularly intended for sparsely sampled data with high dimensionality, a comparison is presented between the extension method and band coaddition.

Twede, David R.; Hayden, Andreas F.

2004-01-01

284

Optimal cut for leaky SAW on LiTaO3 for high performance resonators and filters.  

PubMed

The paper describes how the characteristics of leaky surface acoustic wave (LSAW) propagation depend on the thickness of Al grating electrodes on rotated Y-X LiTaO3. It is shown that the propagation loss arising from leaky nature changes parabolically with both the grating electrode thickness and rotation angle and becomes zero when electrode thickness and rotation angle are properly determined. This means that even when thick grating electrodes are needed in device design, zero propagation loss is always realized by properly determining the rotation angle. When the grating electrode thickness is 0.07 to 0.1 in wavelength for example, LSAWs on 40-42 degrees Y-X LiTaO3 give zero propagation loss without deteriorating other characteristics. Ladder-type filters for the 800-MHz range were fabricated, which essentially need thick Al grating electrodes of about 0.1 wavelength thickness. As predicted by theoretical calculation, experimental results showed that if the rotation angle is increased to circa 420 from a conventional value of 36 degrees, the insertion loss and shape factor are markedly improved compared with devices based on 36 degrees Y-X LiTaO3. This is essentially a result of the minimized propagation loss. PMID:11570771

Kawachi, O; Mineyoshi, S; Endoh, G; Uedo, M; Ikata, O; Hashimoto, K Y; Yamaguchi, M

2001-09-01

285

An efficient one-step condensation and activation strategy to synthesize porous carbons with optimal micropore sizes for highly selective CO2 adsorption  

NASA Astrophysics Data System (ADS)

A series of microporous carbons (MPCs) were successfully prepared by an efficient one-step condensation and activation strategy using commercially available dialdehyde and diamine as carbon sources. The resulting MPCs have large surface areas (up to 1881 m2 g-1), micropore volumes (up to 0.78 cm3 g-1), and narrow micropore size distributions (0.7-1.1 nm). The CO2 uptakes of the MPCs prepared at high temperatures (700-750 °C) are higher than those prepared under mild conditions (600-650 °C), because the former samples possess optimal micropore sizes (0.7-0.8 nm) that are highly suitable for CO2 capture due to enhanced adsorbate-adsorbent interactions. At 1 bar, MPC-750 prepared at 750 °C demonstrates the best CO2 capture performance and can efficiently adsorb CO2 molecules at 2.86 mmol g-1 and 4.92 mmol g-1 at 25 and 0 °C, respectively. In particular, the MPCs with optimal micropore sizes (0.7-0.8 nm) have extremely high CO2/N2 adsorption ratios (47 and 52 at 25 and 0 °C, respectively) at 1 bar, and initial CO2/N2 adsorption selectivities of up to 81 and 119 at 25 °C and 0 °C, respectively, which are far superior to previously reported values for various porous solids. These excellent results, combined with good adsorption capacities and efficient regeneration/recyclability, make these carbons amongst the most promising sorbents reported so far for selective CO2 adsorption in practical applications.A series of microporous carbons (MPCs) were successfully prepared by an efficient one-step condensation and activation strategy using commercially available dialdehyde and diamine as carbon sources. The resulting MPCs have large surface areas (up to 1881 m2 g-1), micropore volumes (up to 0.78 cm3 g-1), and narrow micropore size distributions (0.7-1.1 nm). The CO2 uptakes of the MPCs prepared at high temperatures (700-750 °C) are higher than those prepared under mild conditions (600-650 °C), because the former samples possess optimal micropore sizes (0.7-0.8 nm) that are highly suitable for CO2 capture due to enhanced adsorbate-adsorbent interactions. At 1 bar, MPC-750 prepared at 750 °C demonstrates the best CO2 capture performance and can efficiently adsorb CO2 molecules at 2.86 mmol g-1 and 4.92 mmol g-1 at 25 and 0 °C, respectively. In particular, the MPCs with optimal micropore sizes (0.7-0.8 nm) have extremely high CO2/N2 adsorption ratios (47 and 52 at 25 and 0 °C, respectively) at 1 bar, and initial CO2/N2 adsorption selectivities of up to 81 and 119 at 25 °C and 0 °C, respectively, which are far superior to previously reported values for various porous solids. These excellent results, combined with good adsorption capacities and efficient regeneration/recyclability, make these carbons amongst the most promising sorbents reported so far for selective CO2 adsorption in practical applications. Electronic supplementary information (ESI) available: Fig. S1-13 and Table S1. See DOI: 10.1039/c3nr05825e

Wang, Jiacheng; Liu, Qian

2014-03-01

286

[Application of N-isopropyl-p-[123I] iodoamphetamine quantification of regional cerebral blood flow using iterative reconstruction methods: selection of the optimal reconstruction method and optimization of the cutoff frequency of the preprocessing filter].  

PubMed

In cerebral blood flow tests using N-Isopropyl-p-[123I] Iodoamphetamine "I-IMP, quantitative results of greater accuracy than possible using the autoradiography (ARG) method can be obtained with attenuation and scatter correction and image reconstruction by filtered back projection (FBP). However, the cutoff frequency of the preprocessing Butterworth filter affects the quantitative value; hence, we sought an optimal cutoff frequency, derived from the correlation between the FBP method and Xenon-enhanced computed tomography (XeCT)/cerebral blood flow (CBF). In this study, we reconstructed images using ordered subsets expectation maximization (OSEM), a method of successive approximation which has recently come into wide use, and also three-dimensional (3D)-OSEM, a method by which the resolution can be corrected with the addition of collimator broad correction, to examine the effects on the regional cerebral blood flow (rCBF) quantitative value of changing the cutoff frequency, and to determine whether successive approximation is applicable to cerebral blood flow quantification. Our results showed that quantification of greater accuracy was obtained with reconstruction employing the 3D-OSEM method and using a cutoff frequency set near 0.75-0.85 cycles/cm, which is higher than the frequency used in image reconstruction by the ordinary FBP method. PMID:23964534

Asazu, Akira; Hayashi, Masuo; Arai, Mami; Kumai, Yoshiaki; Akagi, Hiroyuki; Okayama, Katsuyoshi; Narumi, Yoshifumi

2013-05-01

287

Rapid one-step purification of single-cells encapsulated in alginate microcapsules from oil to aqueous phase using a hydrophobic filter paper: Implications for single-cell experiments.  

PubMed

By virtue of the biocompatibility and physical properties of hydrogel, picoliter-sized hydrogel microcapsules have been considered to be a biometric signature containing several features similar to that of encapsulated single cells, including phenotype, viability, and intracellular content. To maximize the experimental potential of encapsulating cells in hydrogel microcapsules, a method that enables efficient hydrogel microcapsule purification from oil is necessary. Current methods based on centrifugation for the conventional stepwise rinsing of oil, are slow and laborious and decrease the monodispersity and yield of the recovered hydrogel microcapsules. To remedy these shortcomings we have developed a simple one-step method to purify alginate microcapsules, containing a single live cell, from oil to aqueous phase. This method employs oil impregnation using a commercially available hydrophobic filter paper without multistep centrifugal purification and complicated microchannel networks. The oil-suspended alginate microcapsules encapsulating single cells from mammalian cancer cell lines (MCF-7, HepG2, and U937) and microorganisms (Chlorella vulgaris) were successfully exchanged to cell culture media by quick (?10 min) depletion of the surrounding oil phase without coalescence of neighboring microcapsules. Cell proliferation and high integrity of the microcapsules were also demonstrated by long-term incubation of microcapsules containing a single live cell. We expect that this method for the simple and rapid purification of encapsulated single-cell microcapsules will attain widespread adoption, assisting cell biologists and clinicians in the development of single-cell experiments. PMID:25130499

Lee, Do-Hyun; Jang, Miran; Park, Je-Kyun

2014-10-01

288

High accuracy motor controller for positioning optical filters in the CLAES Spectrometer  

NASA Astrophysics Data System (ADS)

The Etalon Drive Motor (EDM), a precision etalon control system designed for accurate positioning of etalon filters in the IR spectrometer of the Cryogenic Limb Array Etalon Spectrometer (CLAES) experiment is described. The EDM includes a brushless dc torque motor, which has an infinite resolution for setting an etalon filter to any desired angle, a four-filter etalon wheel, and an electromechanical resolver for angle information. An 18-bit control loop provides high accuracy, resolution, and stability. Dynamic computer interaction allows the user to optimize the step response. A block diagram of the motor controller is presented along with a schematic of the digital/analog converter circuit.

Thatcher, John B.

289

Optimal Placement of Pressure Monitoring Wells for CO2 Leakage Detection based on a Kalman filter and a Multi-Objective Genetic Algorithm  

NASA Astrophysics Data System (ADS)

Measurement of pressure changes in monitoring wells located in a formation overlying an injection formation can provide an early warning for CO2 or brine leakage. If this strategy is to be part of an overall monitoring framework, then questions about how many monitoring wells are needed to detect a leakage event, and where should these well be placed, need to be addressed. In this study we present a methodology that uses a combination of a Kalman filter, a physically-based analytical model that solves for pressure propagation across old/abandoned leaky wells in a multi-formation system, and a multi-objective genetic algorithm, to answer the questions of how many wells should be used and where should they be placed. The Kalman filter is used to explore the covariance reduction based on possible well positions. The physically-based model is used to simulate, in a Monte Carlo scheme, a wide range of possible leakage scenarios where the random variable is the permeability of the old/abandoned leaky wells. The multi-objective genetic algorithm employed in this work is the Non-dominated Sorting Genetic Algorithm (NSGA-II), which is used to optimize three objectives: (i)The reduction of the total variance of the pressure field, (ii) the reduction of the number of wells used to detect a leakage event, and (iii) the reduction of the detection of leakage events which are not "harmful". In this work a "harmful" leakage event refers to an event in which the pressure change in the monitoring formation is large enough to induce leakage into the deepest potable water formation. The methodology is applied to a synthetic case study, which serves to prove the applicability of the methods and to gather insights on the strengths and weaknesses of using pressure monitoring wells to detect a CO2 leakage event.

Nogues, J. P.; Nordbotten, J. M.; Celia, M. A.

2012-12-01

290

Building Gabor Filters from Retinal Responses  

Microsoft Academic Search

Starting from a biologically inspired framework, Gabor filters were built up from retinal filters via LMSE algorithms. A subset of retinal filter kernels was chosen to form a particular Gabor filter by using a weighted sum. One-dimensional optimization approaches were shown to be inappropriate for the problem. All model parameters were fixed with biological or image processing constraints. Detailed analysis

Johannes Partzsch; Christian Mayr; Rene Schuffny

291

Disk filter  

DOEpatents

An electric disk filter provides a high efficiency at high temperature. A hollow outer filter of fibrous stainless steel forms the ground electrode. A refractory filter material is placed between the outer electrode and the inner electrically isolated high voltage electrode. Air flows through the outer filter surfaces through the electrified refractory filter media and between the high voltage electrodes and is removed from a space in the high voltage electrode.

Bergman, Werner (Pleasanton, CA)

1986-01-01

292

Disk filter  

DOEpatents

An electric disk filter provides a high efficiency at high temperature. A hollow outer filter of fibrous stainless steel forms the ground electrode. A refractory filter material is placed between the outer electrode and the inner electrically isolated high voltage electrode. Air flows through the outer filter surfaces through the electrified refractory filter media and between the high voltage electrodes and is removed from a space in the high voltage electrode.

Bergman, W.

1985-01-09

293

Factoring wavelet transforms into lifting steps  

Microsoft Academic Search

This article is essentially tutorial in nature. We show how any discrete wavelet transform or two band subband filtering with\\u000a finite filters can be decomposed into a finite sequence of simple filtering steps, which we call lifting steps but that are\\u000a also known as ladder structures. This decomposition corresponds to a factorization of the polyphase matrix of the wavelet\\u000a or

Ingrid Daubechies; Wim Sweldens

1998-01-01

294

Filtering Water  

NSDL National Science Digital Library

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

Brieske, Joel A.

2003-01-01

295

Water Filters  

NASA Technical Reports Server (NTRS)

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

1993-01-01

296

Biological Filters.  

ERIC Educational Resources Information Center

Presents the 1978 literature review of wastewater treatment. The review is concerned with biological filters, and it covers: (1) trickling filters; (2) rotating biological contractors; and (3) miscellaneous reactors. A list of 14 references is also presented. (HM)

Klemetson, S. L.

1978-01-01

297

Approximating optimal state estimation  

Microsoft Academic Search

Minimising forecast error requires accurately specifying the initial state from which the forecast is made by optimally using available observing resources to obtain the most accurate possible analysis. The Kalman filter accomplishes this for linear sys- tems and experience shows that the extended Kalman filter also performs well in non-linear systems. Unfortunately, the Kalman filter and the extended Kalman filter

Brian F. Farrell; Petros J. Ioannou

2006-01-01

298

Metallic Filters  

NASA Technical Reports Server (NTRS)

Filtration technology originated in a mid 1960's NASA study. The results were distributed to the filter industry, an HR Textron responded, using the study as a departure for the development of 421 Filter Media. The HR system is composed of ultrafine steel fibers metallurgically bonded and compressed so that the pore structure is locked in place. The filters are used to filter polyesters, plastics, to remove hydrocarbon streams, etc. Several major companies use the product in chemical applications, pollution control, etc.

1985-01-01

299

Water Filters  

NASA Technical Reports Server (NTRS)

A compact, lightweight electrolytic water filter generates silver ions in concentrations of 50 to 100 parts per billion in the water flow system. Silver ions serve as effective bactericide/deodorizers. Ray Ward requested and received from NASA a technical information package on the Shuttle filter, and used it as basis for his own initial development, a home use filter.

1987-01-01

300

A unified framework for mode filtering and the maximum a posteriori mode filter  

E-print Network

the subclass of mode filtering problems in which the mode estimates are linear functions of the observed pres mode shape filter is the optimal linear mode filter for the detection and estimation of any single mode Gaussian random variables CGRV's 5­8 neither of these filters attains the bound on the minimum mean square

Wage, Kathleen

301

Filter Buffy Coats (FBC): A source of peripheral blood leukocytes recovered from leukocyte depletion filters  

Microsoft Academic Search

In compliance with federal regulations, blood banks routinely use leukocyte depletion filters to eliminate contaminating leukocytes from blood products such as red blood cell and platelet concentrates. We developed and optimized conditions to elute leukocytes adsorbed to these filters; resulting in leukocyte suspensions which we termed Filter Buffy Coats (FBCs). These Filter Buffy Coats can replace standard buffy coats for

T. P. H. Meyer; I. Zehnter; B. Hofmann; J. Zaisserer; J. Burkhart; S. Rapp; F. Weinauer; J. Schmitz; W. E. Illert

2005-01-01

302

Method of statistical filtering  

NASA Technical Reports Server (NTRS)

Minimal formula for bounding the cross correlation between a random forcing function and the state error when this correlation is unknown is used in optimal linear filter theory applications. Use of the bound results in overestimation of the estimation-error covariance.

Battin, R. H.; Deckert, J. C.; Fraser, D. C.; Potter, J. E.

1970-01-01

303

Evaluation of various speckle reduction filters on medical ultrasound images.  

PubMed

At present, ultrasound is one of the essential tools for noninvasive medical diagnosis. However, speckle noise is inherent in medical ultrasound images and it is the cause for decreased resolution and contrast-to-noise ratio. Low image quality is an obstacle for effective feature extraction, recognition, analysis, and edge detection; it also affects image interpretation by doctor and the accuracy of computer-assisted diagnostic techniques. Thus, speckle reduction is significant and critical step in pre-processing of ultrasound images. Many speckle reduction techniques have been studied by researchers, but to date there is no comprehensive method that takes all the constraints into consideration. In this paper we discuss seven filters, namely Lee, Frost, Median, Speckle Reduction Anisotropic Diffusion (SRAD), Perona-Malik's Anisotropic Diffusion (PMAD) filter, Speckle Reduction Bilateral Filter (SRBF) and Speckle Reduction filter based on soft thresholding in the Wavelet transform. A comparative study of these filters has been made in terms of preserving the features and edges as well as effectiveness of de-noising.We computed five established evaluation metrics in order to determine which despeckling algorithm is most effective and optimal for real-time implementation. In addition, the experimental results have been demonstrated by filtered images and statistical data table. PMID:24109896

Wu, Shibin; Zhu, Qingsong; Xie, Yaoqin

2013-01-01

304

Integrated SIW filter and microstrip antenna  

Microsoft Academic Search

A novel design of integrated Substrate Integrated Waveguide (SIW) filter and microstrip antenna is proposed. In the first step, the methodology consists of synthesising the subsystems combining a filter and an antenna using lumped lowpass prototype networks. To realise the concept, the filtering and radiating functions are combined using multilayer technology on a printed circuit board (PCB). The design is

Hizamel M. Hizan; Ian C. Hunter; Alaa I. Abunjaileh

2010-01-01

305

Implementation of Fluidigm's SlingShot™ Absolute Quantitation Product offers the dual advantage of replacing the costly and time-consuming titration step as well as recovery of sub-optimal DNA Samples for Roche 454 Next Generation Sequencing  

Microsoft Academic Search

We have successfully implemented Fluidigm's SlingShot™ technology into our 454 sequencing process at two key junctions: sub-optimal sample quantitation and replacement of the library titration. This implementation has allowed us to process previously failed samples (Roche recommends samples be between 3ug and 5ug) and replace the costly titration step, saving us processing time (up to 2 days) plus the cost

Joseph F. Boland; Casey A. Matthews; Jennifer A. Bacior; Victor Lonsberry; Zuoming Deng; Laufey Amundadottir; Stephen J. Chanock

306

High-resolution wave-theory-based ultrasound reflection imaging using the split-step fourier and globally optimized fourier finite-difference methods  

DOEpatents

Methods for enhancing ultrasonic reflection imaging are taught utilizing a split-step Fourier propagator in which the reconstruction is based on recursive inward continuation of ultrasonic wavefields in the frequency-space and frequency-wave number domains. The inward continuation within each extrapolation interval consists of two steps. In the first step, a phase-shift term is applied to the data in the frequency-wave number domain for propagation in a reference medium. The second step consists of applying another phase-shift term to data in the frequency-space domain to approximately compensate for ultrasonic scattering effects of heterogeneities within the tissue being imaged (e.g., breast tissue). Results from various data input to the method indicate significant improvements are provided in both image quality and resolution.

Huang, Lianjie

2013-10-29

307

Implementation of Kalman Filter with Python Language  

E-print Network

In this paper, we investigate the implementation of a Python code for a Kalman Filter using the Numpy package. A Kalman Filtering is carried out in two steps: Prediction and Update. Each step is investigated and coded as a function with matrix input and output. These different functions are explained and an example of a Kalman Filter application for the localization of mobile in wireless networks is given.

Laaraiedh, Mohamed

2012-01-01

308

Filtering apparatus  

DOEpatents

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

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

1992-01-01

309

Filtering apparatus  

DOEpatents

A vertical vessel is described having a lower inlet and an upper outlet enclosure separated by a main horizontal tube sheet. The inlet enclosure receives the flue gas from a boiler of a power system and the outlet enclosure supplies cleaned gas to the turbines. The inlet enclosure contains a plurality of particulate-removing clusters, each having a plurality of filter units. Each filter unit includes a filter clean-gas chamber defined by a plate and a perforated auxiliary tube sheet with filter tubes suspended from each tube sheet and a tube connected to each chamber for passing cleaned gas to the outlet enclosure. The clusters are suspended from the main tube sheet with their filter units extending vertically and the filter tubes passing through the tube sheet and opening in the outlet enclosure. The flue gas is circulated about the outside surfaces of the filter tubes and the particulate is absorbed in the pores of the filter tubes. Pulses to clean the filter tubes are passed through their inner holes through tubes free of bends which are aligned with the tubes that pass the clean gas. 18 figs.

Haldipur, G.B.; Dilmore, W.J.

1992-09-01

310

PWM Control Techniques for Rectifier Filter Minimization  

Microsoft Academic Search

Minimization of input\\/output filters is an essential step towards manufacturing compact low-cost static power supplies. Three PWM control techniques that yield substantial filter size reduction for three-phase (self-commutated) rectifiers are presented and analyzed. Filters required by typical line-commutated rectifiers are used as the basis for comparison. Moreover, it is shown that in addition to filter minimization two of the proposed

Phoivas D. Ziogas; Young-Goo Kang; Victor R. Stefanovic

1985-01-01

311

WIENER FILTER DESIGN USING POLYNOMIAL EQUATIONS  

E-print Network

: a filtering and a generalized deconvolution problem. A new solvability con­ dition for linear polynomial in a novel way, within the polynomial equations approach to linear filtering problems. The process fractions in multi­ variable problems). Optimal filters are designed by solving spectral factoriza­ tions

312

An imaging filter for biological applications  

Microsoft Academic Search

A recently developed post-column imaging filter optimized for biological electron microscopy is described. The filter uses a single magnetic prism, four strong quadrupole lenses and five sextupole lenses to form images and spectra free of all important aberrations and distortions of first and second order. The performance of the filter is illustrated with practical applications. It is shown that the

O. L. Krivanek; S. L. Friedman; A. J. Gubbens; B. Kraus

1995-01-01

313

Water Filter  

NSDL National Science Digital Library

In this engineering activity, challenge learners to invent a water filter that cleans dirty water. Learners construct a filter device out of a 2-liter bottle and then experiment with different materials like gravel, sand, and cotton balls to see which is the most effective. Safety note: An adult's help is needed for this activity.

Boston, Wgbh

2002-01-01

314

Bayesian iterative binary filter design  

NASA Astrophysics Data System (ADS)

Optimal translation-invariant binary windowed filters are determined by probabilities of the form P(Y equals 1|x), where x is a vector (template) of observed values in the observation window and Y is the value in the image to be estimated by the filter. The optimal window filter is defined by y(x) equals 1 if P(Y equals 1|x) (greater than) 0.5 and y(x) equals 0 if P(Y equals 1|x) (less than or equal to) 0.5, which is the binary conditional expectation. The fundamental problem of filter design is to estimate P(Y equals 1|x) from data (image realizations), where x ranges over all possible observation vectors in the window. A Bayesian approach to the problem can be employed by assuming, for each x, a prior distribution for P(Y equals 1|x). These prior distributions result from considering a range of model states by which the observed images are obtained from the ideal. Instead of estimating P(Y equals 1|x) directly from observations by its sample mean relative to an image sample, P(Y equals 1|x) is estimated in the Bayesian fashion, its Bayes estimator being the conditional expectation of P(Y equals 1|x) given the data. Recently the authors have shown that, with accurate prior information, the Bayesian multiresolution filter has significant benefits from multiresolution filter design. Further, since the Bayesian filter is trained over a wider range of degradation levels, it inherits the added benefit of filtering a degraded image at different degradation levels in addition permitting iterative filtering. We discuss the necessary conditions that make a binary filter a good iterative filter and show that the Bayesian multiresolution filter is a natural candidate.

Kamat, Vishnu G.; Dougherty, Edward R.

2001-05-01

315

Microwave assisted biodiesel production from Jatropha curcas L. seed by two-step in situ process: optimization using response surface methodology.  

PubMed

The synthesis of fatty acid ethyl esters (FAEEs) by a two-step in situ (reactive) esterification/transesterification from Jatropha curcas L. (JCL) seeds using microwave system has been investigated. Free fatty acid was reduced from 14% to less than 1% in the first step using H2SO4 as acid catalyst after 35 min of microwave irradiation heating. The organic phase in the first step was subjected to a second reaction by adding 5 N KOH in ethanol as the basic catalyst. Response surface methodology (RSM) based on central composite design (CCD) was utilized to design the experiments and analyze the influence of process variables (particles seed size, time of irradiation, agitation speed and catalyst loading) on conversion of triglycerides (TGs) in the second step. The highest triglycerides conversion to fatty acid ethyl esters (FAEEs) was 97.29% at the optimum conditions:<0.5mm seed size, 12.21 min irradiation time, 8.15 ml KOH catalyst loading and 331.52 rpm agitation speed in the 110 W microwave power system. PMID:23567732

Jaliliannosrati, Hamidreza; Amin, Nor Aishah Saidina; Talebian-Kiakalaieh, Amin; Noshadi, Iman

2013-05-01

316

Implementation of Kalman Filter with Python Language Mohamed LAARAIEDH  

E-print Network

- 1 - Implementation of Kalman Filter with Python Language Mohamed LAARAIEDH IETR Labs, University of a Python code for a Kalman Filter using the Numpy package. A Kalman Filtering is carried out in two steps. These different functions are explained and an example of a Kalman Filter application for the localization

Paris-Sud XI, Université de

317

Optimization of Xylanase Production from Penicillium sp.WX-Z1 by a Two-Step Statistical Strategy: Plackett-Burman and Box-Behnken Experimental Design  

PubMed Central

The objective of the study was to optimize the nutrition sources in a culture medium for the production of xylanase from Penicillium sp.WX-Z1 using Plackett-Burman design and Box-Behnken design. The Plackett-Burman multifactorial design was first employed to screen the important nutrient sources in the medium for xylanase production by Penicillium sp.WX-Z1 and subsequent use of the response surface methodology (RSM) was further optimized for xylanase production by Box-Behnken design. The important nutrient sources in the culture medium, identified by the initial screening method of Placket-Burman, were wheat bran, yeast extract, NaNO3, MgSO4, and CaCl2. The optimal amounts (in g/L) for maximum production of xylanase were: wheat bran, 32.8; yeast extract, 1.02; NaNO3, 12.71; MgSO4, 0.96; and CaCl2, 1.04. Using this statistical experimental design, the xylanase production under optimal condition reached 46.50 U/mL and an increase in xylanase activity of 1.34-fold was obtained compared with the original medium for fermentation carried out in a 30-L bioreactor. PMID:22949884

Cui, Fengjie; Zhao, Liming

2012-01-01

318

Aquatic Plants Aid Sewage Filter  

NASA Technical Reports Server (NTRS)

Method of wastewater treatment combines micro-organisms and aquatic plant roots in filter bed. Treatment occurs as liquid flows up through system. Micro-organisms, attached themselves to rocky base material of filter, act in several steps to decompose organic matter in wastewater. Vascular aquatic plants (typically, reeds, rushes, cattails, or water hyacinths) absorb nitrogen, phosphorus, other nutrients, and heavy metals from water through finely divided roots.

Wolverton, B. C.

1985-01-01

319

Optimization of activated carbon production from empty fruit bunch fibers in one-step steam pyrolysis for cadmium removal from aqueous solution  

Microsoft Academic Search

The fast growth of the palm oil industry in Malaysia is associated with various waste products, namely the empty fruit bunches\\u000a (EFB), which have a negative impact on the environment. Therefore, these wastes were utilized as a cheap raw material for\\u000a the production of activated carbon (AC) with less energy consumption. One-step steam pyrolysis was used to produce AC from

Ma’an F. Alkhatib; Suleyman A. Muyibi; Jeminat Omotayo Amode

320

Influence of multi-step heat treatments in creep age forming of 7075 aluminum alloy: Optimization for springback, strength and exfoliation corrosion  

SciTech Connect

Multi-step heat treatments comprise of high temperature forming (150 Degree-Sign C/24 h plus 190 Degree-Sign C for several minutes) and subsequent low temperature forming (120 Degree-Sign C for 24 h) is developed in creep age forming of 7075 aluminum alloy to decrease springback and exfoliation corrosion susceptibility without reduction in tensile properties. The results show that the multi-step heat treatment gives the low springback and the best combination of exfoliation corrosion resistance and tensile strength. The lower springback is attributed to the dislocation recovery and more stress relaxation at higher temperature. Transmission electron microscopy observations show that corrosion resistance is improved due to the enlargement in the size and the inter-particle distance of the grain boundaries precipitates. Furthermore, the achievement of the high strength is related to the uniform distribution of ultrafine {eta} Prime precipitates within grains. - Highlights: Black-Right-Pointing-Pointer Creep age forming developed for manufacturing of aircraft wing panels by aluminum alloy. Black-Right-Pointing-Pointer A good combination of properties with minimal springback is required in this component. Black-Right-Pointing-Pointer This requirement can be improved through the appropriate heat treatments. Black-Right-Pointing-Pointer Multi-step cycles developed in creep age forming of AA7075 for improving of springback and properties. Black-Right-Pointing-Pointer Results indicate simultaneous enhancing the properties and shape accuracy (lower springback).

Arabi Jeshvaghani, R.; Zohdi, H. [Department of Materials Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of)] [Department of Materials Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Shahverdi, H.R., E-mail: shahverdi@modares.ac.ir [Department of Materials Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Bozorg, M. [Department of Materials Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of)] [Department of Materials Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Hadavi, S.M.M. [School of Materials Science and Engineering, MA University of Technology, P.O. Box 16765-3197, Tehran (Iran, Islamic Republic of)] [School of Materials Science and Engineering, MA University of Technology, P.O. Box 16765-3197, Tehran (Iran, Islamic Republic of)

2012-11-15

321

Filtering in SPECT Image Reconstruction  

PubMed Central

Single photon emission computed tomography (SPECT) imaging is widely implemented in nuclear medicine as its clinical role in the diagnosis and management of several diseases is, many times, very helpful (e.g., myocardium perfusion imaging). The quality of SPECT images are degraded by several factors such as noise because of the limited number of counts, attenuation, or scatter of photons. Image filtering is necessary to compensate these effects and, therefore, to improve image quality. The goal of filtering in tomographic images is to suppress statistical noise and simultaneously to preserve spatial resolution and contrast. The aim of this work is to describe the most widely used filters in SPECT applications and how these affect the image quality. The choice of the filter type, the cut-off frequency and the order is a major problem in clinical routine. In many clinical cases, information for specific parameters is not provided, and findings cannot be extrapolated to other similar SPECT imaging applications. A literature review for the determination of the mostly used filters in cardiac, brain, bone, liver, kidneys, and thyroid applications is also presented. As resulting from the overview, no filter is perfect, and the selection of the proper filters, most of the times, is done empirically. The standardization of image-processing results may limit the filter types for each SPECT examination to certain few filters and some of their parameters. Standardization, also, helps in reducing image processing time, as the filters and their parameters must be standardised before being put to clinical use. Commercial reconstruction software selections lead to comparable results interdepartmentally. The manufacturers normally supply default filters/parameters, but these may not be relevant in various clinical situations. After proper standardisation, it is possible to use many suitable filters or one optimal filter. PMID:21760768

Lyra, Maria; Ploussi, Agapi

2011-01-01

322

Hybrid Filtering  

Microsoft Academic Search

This paper is concerned with filtering of a hybrid model with a number of linear systems coupled by a hidden switching process.\\u000a The most probable trajectory approach is used to derive a finite-dimensional recursive filter. Such scheme is applied to nonlinear\\u000a systems using a piecewise-linear approximation method. Numerical examples are provided and computational experiments are reported.

Q. Zhang

323

Design and Optimization of Embedded RF Filters using a Hybrid Approach Sidharth Dalmia*, Sung Hwan Min, Seock-Hee Lee, Venky Sundaram and Madhavan Swaminathan  

E-print Network

]. The magnetic coupling of two integrated inductors, which can affect the performance of active circuits, has been studied in [3]. In [4], the authors predict the coupling of inductors based on the substrate coupling effect. A Bluetooth filter, which utilizes the coupling of inductors is discussed in [5

Swaminathan, Madhavan

324

Metal-dielectric photonic devices for spatial filtering and image contrast enhancement  

NASA Astrophysics Data System (ADS)

Propagation of light through layered metamaterials consisting of a metal-dielectric stack may be described as linear spatial filtering. We present the modelling and optimization strategy for engineering such metamaterials, as well as the measurement results of spatial filters consisting of titanium oxide and silver layers evaporated with PVD. Depending on the point spread function, the metamaterial can be applied for subdiffraction spatial filtering or for classical spatial filtering operations. We optimize the metamaterial with respect to the shape of the complex amplitude transfer function, the average transmission coefficient and to average reflections. The shape of the point spread function can only be tailored in a limited degree, due to the limited number of the degrees of freedom contained in the structure, and only in one, planarly or radially oriented dimension. The metamaterial optimised for high-pass filtering consists of several substructures, each of which is an individual cavity, and is optimized by tuning the resonance order of these cavities. In this way we obtain a high transmission for a broad range of spatial frequencies. This metamaterial can be applied to modify the contrast of the object or to introduce a phase-contrast. It may be used for far-field imaging. As an example, we propose to apply it as a novel phase-step visualization photonic element.

Pastuszczak, Anna; Wróbel, Piotr; Stefaniuk, Tomasz; Stolarek, Marcin; Wlaz?o, Mateusz; Koty?ski, Rafa?

2013-05-01

325

Optimization of pressurized liquid extraction using a multivariate chemometric approach and comparison of solid-phase extraction cleanup steps for the determination of polycyclic aromatic hydrocarbons in mosses.  

PubMed

A factorial design was used to optimize the extraction of polycyclic aromatic hydrocarbons (PAHs) from mosses, plants used as biomonitors of air pollution. The analytical procedure consists of pressurized liquid extraction (PLE) followed by solid-phase extraction (SPE) cleanup, in association with analysis by high performance liquid chromatography coupled with fluorescence detection (HPLC-FLD). For method development, homogeneous samples were prepared with large quantities of the mosses Isothecium myosuroides Brid. and Hypnum cupressiforme Hedw., collected from a Spanish Nature Reserve. A factorial design was used to identify the optimal PLE operational conditions: 2 static cycles of 5 min at 80 °C. The analytical procedure performed with PLE showed similar recoveries (?70%) and total PAH concentrations (?200 ng g(-1)) as found using Soxtec extraction, with the advantage of reducing solvent consumption by 3 (30 mL against 100mL per sample), and taking a fifth of the time (24 samples extracted automatically in 8h against 2 samples in 3.5h). The performance of SPE normal phases (NH(2), Florisil, silica and activated aluminium) generally used for organic matrix cleanup was also compared. Florisil appeared to be the most selective phase and ensured the highest PAH recoveries. The optimal analytical procedure was validated with a reference material and applied to moss samples from a remote Spanish site in order to determine spatial and inter-species variability. PMID:22885040

Foan, L; Simon, V

2012-09-21

326

SkyMapper Filter Set: Design and Fabrication of Large Scale Optical Filters  

E-print Network

The SkyMapper Southern Sky Survey will be conducted from Siding Spring Observatory with u, v, g, r, i and z filters that comprise glued glass combination filters of dimension 309x309x15 mm. In this paper we discuss the rationale for our bandpasses and physical characteristics of the filter set. The u, v, g and z filters are entirely glass filters which provide highly uniform band passes across the complete filter aperture. The i filter uses glass with a short-wave pass coating, and the r filter is a complete dielectric filter. We describe the process by which the filters were constructed, including the processes used to obtain uniform dielectric coatings and optimized narrow band anti-reflection coatings, as well as the technique of gluing the large glass pieces together after coating using UV transparent epoxy cement. The measured passbands including extinction and CCD QE are presented.

Bessell, Michael; Schmidt, Brian; Keller, Stefan; Tisserand, Patrick; Francis, Paul

2011-01-01

327

Parameter estimation and asymptotic stability in stochastic filtering  

E-print Network

filtering is how to compute the optimal filter. With the exception of very few cases (for example, linear as part of the state variable and then use some variation of the Interactive Particle Filter to computeParameter estimation and asymptotic stability in stochastic filtering Anastasia Papavasiliou

Del Moral , Pierre

328

Stepped nozzle  

SciTech Connect

An insert is described which allows a supersonic nozzle of a rocket propulsion system to operate at two or more different nozzle area ratios. This provides an improved vehicle flight performance or increased payload. The insert has significant advantages over existing devices for increasing nozzle area ratios. The insert is temporarily fastened by a simple retaining mechanism to the aft end of the diverging segment of the nozzle and provides for a multi-step variation of nozzle area ratio. When mounted in place, the insert provides the nozzle with a low nozzle area ratio. During flight, the retaining mechanism is released and the insert ejected thereby providing a high nozzle area ratio in the diverging nozzle segment. 5 figs.

Sutton, G.P.

1998-07-14

329

Holographic photopolymer linear variable filter with enhanced blue reflection.  

PubMed

A single beam one-step holographic interferometry method was developed to fabricate porous polymer structures with controllable pore size and location to produce compact graded photonic bandgap structures for linear variable optical filters. This technology is based on holographic polymer dispersed liquid crystal materials. By introducing a forced internal reflection, the optical reflection throughout the visible spectral region, from blue to red, is high and uniform. In addition, the control of the bandwidth of the reflection resonance, related to the light intensity and spatial porosity distributions, was investigated to optimize the optical performance. The development of portable and inexpensive personal health-care and environmental multispectral sensing/imaging devices will be possible using these filters. PMID:24517443

Moein, Tania; Ji, Dengxin; Zeng, Xie; Liu, Ke; Gan, Qiaoqiang; Cartwright, Alexander N

2014-03-12

330

The automatic selection of an optimal wavelet filter and its enhancement by the new sparsogram for bearing fault detection. Part 2 of the two related manuscripts that have a joint title as "Two automatic vibration-based fault diagnostic methods using the novel sparsity measurement—Parts 1 and 2"  

NASA Astrophysics Data System (ADS)

Rolling element bearings are the most important components used in machinery. Bearing faults, once they have developed, quickly become severe and can result in fatal breakdowns. Envelope spectrum analysis is one effective approach to detect early bearing faults through the identification of bearing fault characteristic frequencies (BFCFs). To achieve this, it is necessary to find a band-pass filter to retain a resonant frequency band for the enhancement of weak bearing fault signatures. In Part 1 paper, the wavelet packet filters with fixed center frequencies and bandwidths used in a sparsogram may not cover a whole bearing resonant frequency band. Besides, a bearing resonant frequency band may be split into two adjacent imperfect orthogonal frequency bands, which reduce the bearing fault features. Considering the above two reasons, a sparsity measurement based optimal wavelet filter is required to be designed for providing more flexible center frequency and bandwidth for covering a bearing resonant frequency band. Part 2 paper presents an automatic selection process for finding the optimal complex Morlet wavelet filter with the help of genetic algorithm that maximizes the sparsity measurement value. Then, the modulus of the wavelet coefficients obtained by the optimal wavelet filter is used to extract the envelope. Finally, a non-linear function is introduced to enhance the visual inspection ability of BFCFs. The convergence of the optimal filter is fastened by the center frequencies and bandwidths of the optimal wavelet packet nodes established by the new sparsogram. Previous case studies including a simulated bearing fault signal and real bearing fault signals were used to show that the effectiveness of the optimal wavelet filtering method in detecting bearing faults. Finally, the results obtained from comparison studies are presented to verify that the proposed method is superior to the other three popular methods.

Tse, Peter W.; Wang, Dong

2013-11-01

331

Applying sequential Monte Carlo methods into a distributed hydrologic model: lagged particle filtering approach with regularization  

NASA Astrophysics Data System (ADS)

Data assimilation techniques have received growing attention due to their capability to improve prediction. Among various data assimilation techniques, sequential Monte Carlo (SMC) methods, known as "particle filters", are a Bayesian learning process that has the capability to handle non-linear and non-Gaussian state-space models. In this paper, we propose an improved particle filtering approach to consider different response times of internal state variables in a hydrologic model. The proposed method adopts a lagged filtering approach to aggregate model response until the uncertainty of each hydrologic process is propagated. The regularization with an additional move step based on the Markov chain Monte Carlo (MCMC) methods is also implemented to preserve sample diversity under the lagged filtering approach. A distributed hydrologic model, water and energy transfer processes (WEP), is implemented for the sequential data assimilation through the updating of state variables. The lagged regularized particle filter (LRPF) and the sequential importance resampling (SIR) particle filter are implemented for hindcasting of streamflow at the Katsura catchment, Japan. Control state variables for filtering are soil moisture content and overland flow. Streamflow measurements are used for data assimilation. LRPF shows consistent forecasts regardless of the process noise assumption, while SIR has different values of optimal process noise and shows sensitive variation of confidential intervals, depending on the process noise. Improvement of LRPF forecasts compared to SIR is particularly found for rapidly varied high flows due to preservation of sample diversity from the kernel, even if particle impoverishment takes place.

Noh, S. J.; Tachikawa, Y.; Shiiba, M.; Kim, S.

2011-10-01

332

Time optimal, parameters-insensitive digital controller for DC-DC buck converters  

Microsoft Academic Search

In this paper a digital control approach is investigated for time-optimal load step response of DC-DC synchronous buck converters intended for point-of-load applications employing low-ESR ceramic output capacitors. Unlike previously reported approaches, the proposed technique is insensitive to the power stage parameters, as its operation does not rely on the knowledge of the output filter inductance or capacitance. The time-optimal

A. Costabeber; L. Corradini; P. Mattavelli; S. Saggini

2008-01-01

333

Air filter  

SciTech Connect

An air filter is described that has a counter rotating drum, i.e., the rotation of the drum is opposite the tangential intake of air. The intake air has about 1 lb of rock wool fibers per 107 cu. ft. of air sometimes at about 100% relative humidity. The fibers are doffed from the drum by suction nozzle which are adjacent to the drum at the bottom of the filter housing. The drum screen is cleaned by periodically jetting hot dry air at 120 psig through the screen into the suction nozzles.

Jackson, R.E.; Sparks, J.E.

1981-03-03

334

Optimization of one-step real-time reverse transcription-polymerase chain reaction assays for norovirus detection and molecular epidemiology of noroviruses in Thailand.  

PubMed

Noroviruses (NoVs) are an important human pathogen associated with acute viral gastroenteritis worldwide. NoVs display a significant amount of genetic heterogeneity, making it difficult to develop comprehensive detection assays. In this study, primer sets and probes were designed for a TaqMan(®)-based real-time reverse transcription-polymerase chain reaction (RT-PCR) for norovirus detection purposes. The assay was optimized and utilized as a multiplex real-time RT-PCR assay for genogroup I (GI) detection, and a singleplex real-time RT-PCR assay for genogroup II (GII) detection. The assays showed high specificity for NoV detection and no cross-reactivity was observed between GI and GII. The detection limit of the assay was as low as 10 and 50 RNA copies per reaction for GI and GII, respectively. The optimized protocol was employed to assess the presence of NoV strains in clinical samples collected throughout Thailand during December 2005 to November 2006. The percentage of NoV infections among children with acute gastroenteritis (case) was 23.8% (119/500) and for children without acute gastroenteritis (control) it was 6.8% (30/441). The frequency of NoV infections varied geographically, with the highest frequency observed in the central region and the lowest frequency in the northern region (P>0.0001). Of the 149 positive case and control specimens, GII was found to be the predominant genogroup (98.6%). Partial capsid sequences were successfully obtained from 67 NoV-positive specimens and a phylogenetic analysis was performed to genotype the viral strains. GII.4 was the most common genotype detected. PMID:24070785

Neesanant, Pimmnapar; Sirinarumitr, Theerapol; Chantakru, Siriruk; Boonyaprakob, Ukadaj; Chuwongkomon, Kaittawee; Bodhidatta, Ladaporn; Sethabutr, Orntipa; Abente, Eugenio J; Supawat, Krongkaew; Mason, Carl J

2013-12-01

335

Drug Filtering  

NSDL National Science Digital Library

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

Iles, Lawrence F.

2010-01-01

336

C40 on-line demodulation of phase modulated signals using different Kalman filter models  

Microsoft Academic Search

One of several methods to demodulate noisy, angular modulated signals is using Kalman Filtering techniques, offering a combination of two advantages: demodulation and filtering in one step. Different Kalman Filter models have been examined to achieve good filtering and error-reduced demodulation results without consuming too much time. The models usually use at least two inputs for filtering--the quadrature components and

Dirk Balzer; Otmar Loffeld; Christoph Arndt

1997-01-01

337

Particle Filters for State Estimation of Jump Markov Linear Systems  

Microsoft Academic Search

Jump Markov linear systems (JMLS) are linear systems whose parameters evolve with time according to a finite state Markov chain. In this paper, our aim is to recursively com- pute optimal state estimates for this class of systems. We present efficient simulation-based algorithms called particle filters to solve the optimal filtering problem as well as the optimal fixed-lag smoothing problem.

Arnaud Doucet; Neil J. Gordon; Vikram Krishnamurthy

1999-01-01

338

Particle filters for state estimation of jump Markov linear systems  

Microsoft Academic Search

Jump Markov linear systems (JMLS) are linear systems whose parameters evolve with time according to a finite state Markov chain. In this paper, our aim is to recursively compute optimal state estimates for this class of systems. We present efficient simulation-based algorithms called particle filters to solve the optimal filtering problem as well as the optimal fixed-lag smoothing problem. Our

Arnaud Doucet; Neil J. Gordon; Vikram Krishnamurthy

2001-01-01

339

An approach to the approximation problem for nonrecursive digital filters  

Microsoft Academic Search

A direct design procedure for nonrecursive digital filters, based primarily on the frequency-response characteristic of the desired filters, is presented. An optimization technique is used to minimize the maximum deviation of the synthesized filter from the ideal filter over some frequence range. Using this frequency-sampling technique, a wide variety of low-pass and bandpass filters have been designed, as well as

LAWRENCE R. RABINER; BERNARD GOLD; C. McGonegal

1970-01-01

340

The Lockheed alternate partial polarizer universal filter  

NASA Technical Reports Server (NTRS)

A tunable birefringent filter using an alternate partial polarizer design has been built. The filter has a transmission of 38% in polarized light. Its full width at half maximum is .09A at 5500A. It is tunable from 4500 to 8500A by means of stepping motor actuated rotating half wave plates and polarizers. Wave length commands and thermal compensation commands are generated by a PPD 11/10 minicomputer. The alternate partial polarizer universal filter is compared with the universal birefringent filter and the design techniques, construction methods, and filter performance are discussed in some detail. Based on the experience of this filter some conclusions regarding the future of birefringent filters are elaborated.

Title, A. M.

1976-01-01

341

Nonlinear filtering in oil/gas reservoir simulation: filter design  

SciTech Connect

In order to provide an additional mode of utility to the USGS reservoir model VARGOW, a nonlinear filter was designed and incorporated into the system. As a result, optimal (in the least squares sense) estimates of reservoir pressure, liquid mass, and gas cap plus free gas mass are obtained from an input of reservoir initial condition estimates and pressure history. These optimal estimates are provided continuously for each time after the initial time, and the input pressure history is allowed to be corrupted by measurement error. Preliminary testing of the VARGOW filter was begun and the results show promise. Synthetic data which could be readily manipulated during testing was used in tracking tests. The results were positive when the initial estimates of the reservoir initial conditions were reasonably close. Further testing is necessary to investigate the filter performance with real reservoir data.

Arnold, E.M.; Voss, D.A.; Mayer, D.W.

1980-10-01

342

Application Analysis of RLS Adaptive Filter in Signal Noise Removing and Simulation  

Microsoft Academic Search

In the process of digital signal processing, the random signal, noise and time-varying signal must be dealt with. The adoption of digital filters with fixed coefficient can not realize the optimized filter. Therefore it is necessary to design an adaptive filter to track the changes of the signal and noise in order to realize optimal filtering. This paper introduces the

Xing Guo-Quan; Zhao Yuan

2010-01-01

343

Discrete-time filtering of linear continuous-time processes  

NASA Astrophysics Data System (ADS)

Continuous-time measurements are prefiltered before sampling, to remove additive white noise. The discrete-time optimal filter comprises a digital algorithm which is applied to the prefiltered, sampled measurements; the algorithm is based on the discrete-time equivalent model of the overall system. For the case of an integrate-and-dump analog prefilter, a discrete-time equivalent model was developed and the corresponding optimal filter was found for the general case, where the continuous-time measurement and process noise signals are correlated. A commonly used approximate discrete-time model was analyzed by defining and evaluating the true-error-covariance matrix of the estimate, and comparing it with the supposed error covariance matrix. It was shown that there is a class of unstable processes for which the former error covariance matrix attains unbounded norm, in spite of the continuing bounded nature of the other error covariance matrix. The main part of the thesis concerns the problem of finding an optimal prefilter. The steps of obtaining the optimal prefilter comprise: deriving a discrete-time equivalent-model of the overall system; finding the equation which is satisfied by the error covariance matrix; deriving the expressions which are satisfied by the first coefficients of the Maclaurin expansions of the error covariance matrix in the small parameter T; and obtaining the optimal prefilter by matrix optimization. The results obtained indicate that the optimal prefilter may be implemented through systems of different orders; the minimum order required is discussed, which is of great practical importance as the simplest possible prefilter. In discussion of the problem of discrete-time quadratic regulation of linear continuous time processes, the case of practical interest, where a zero-order hold is part of the digital-to-analog converter, is considered. It is shown that the duality between the regulation and filtering problems is not conserved after discretization when an integrate-and-dump prefilter is used. Analysis of a specific model shows that the results obtained in the regulation problem are completely different from those obtained in the filtering problem.

Shats, Samuel

1989-06-01

344

Collaborative emitter tracking using Rao-Blackwellized random exchange diffusion particle filtering  

NASA Astrophysics Data System (ADS)

We introduce in this paper the fully distributed, random exchange diffusion particle filter (ReDif-PF) to track a moving emitter using multiple received signal strength (RSS) sensors. We consider scenarios with both known and unknown sensor model parameters. In the unknown parameter case, a Rao-Blackwellized (RB) version of the random exchange diffusion particle filter, referred to as the RB ReDif-PF, is introduced. In a simulated scenario with a partially connected network, the proposed ReDif-PF outperformed a PF tracker that assimilates local neighboring measurements only and also outperformed a linearized random exchange distributed extended Kalman filter (ReDif-EKF). Furthermore, the novel ReDif-PF matched the tracking error performance of alternative suboptimal distributed PFs based respectively on iterative Markov chain move steps and selective average gossiping with an inter-node communication cost that is roughly two orders of magnitude lower than the corresponding cost for the Markov chain and selective gossip filters. Compared to a broadcast-based filter which exactly mimics the optimal centralized tracker or its equivalent (exact) consensus-based implementations, ReDif-PF showed a degradation in steady-state error performance. However, compared to the optimal consensus-based trackers, ReDif-PF is better suited for real-time applications since it does not require iterative inter-node communication between measurement arrivals.

Bruno, Marcelo G. S.; Dias, Stiven S.

2014-12-01

345

Water Filter  

NASA Technical Reports Server (NTRS)

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

1982-01-01

346

Plasmonic filters.  

SciTech Connect

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

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

2009-09-01

347

Drug Filtering  

NSDL National Science Digital Library

This lesson from Illuminations looks at exponential decay. The example of how kidneys filter blood is used. The material asks students to determine the amount of a drug that remains in the body over a period of time. Students will predict behavior by an exponential decay model and graph an exponential set of data. The lesson is appropriate for grades 9-12 and should require 1 class period to complete.

2010-12-06

348

Eyeglass Filters  

NASA Technical Reports Server (NTRS)

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

1987-01-01

349

Nonlinear Filtering with Fractional Brownian Motion  

SciTech Connect

Our objective is to study a nonlinear filtering problem for the observation process perturbed by a Fractional Brownian Motion (FBM) with Hurst index 1/2 optimal filter is derived.

Amirdjanova, A. [Department of Statistics, University of Michigan, Ann Arbor, MI 48109-1092 (United States)

2002-12-19

350

Dust filter apparatus  

SciTech Connect

Dust filter equipment includes a fibrous mat filter (37) having a low fibre density and a low loft so that when water is fed onto the filter it saturates the filter throughout its thickness and flows freely down the filter to form an effectively continuous body of water having a thickness virtually equal to the thickness of the mat filter.

James, G.C.

1981-03-03

351

An Introduction to PALM: Filtering Filter methods  

E-print Network

of continuity: ui xi = 0 Equations for scalar variables: t = - (ui) xi ´ The filtering process provides the non-linear + ujui + uiuj ´ Non-linear term is entirely written as a function of filtered and sub-filter scales (ui to evaluate the terms directly from the filtered variables « uiuj cannot be calculated directly, requires

Raasch, Siegfried

352

Relative Navigation In Elliptical Orbits Using An Iterative Nonlinear Filter  

NASA Technical Reports Server (NTRS)

The two step filter is applied to process intersatellite radar measurements to determine the motion of one satellite relative to another in close elliptical orbits. This filter breaks a nonlinear estimation problem into two state vectors. The 'first step' state is chosen so as to have a linear measurement equation. This is nonlinearly related to the 'second step' state which describes the dynamics. Two different forms are used. In one, the first step state is the second step state vector augmented by the measurement equation. In the other, the first step and second step state vectors are of equal dimension. The two step filter is compared against an iterated extended Kalman filter and a Kalman filter using a change of variables. Analytical differences between the two step estimator and these conventional filters are highlighted. Special concerns for initializing the first step state covariance matrix and handling the possibility of numerically rank deficient covariance matrices are addressed. Numerical simulations are performed which show that the Two Step estimator produces a lower estimation bias under two circumstances; large apriori initial error; and small dimension observation vectors which require a longer arc of measurements to generate observability of the state.

Garrison, James L.; Axelrad, Penina

1997-01-01

353

Comparing 2D matched filter response and Gabor filter methods for vessel segmentation in retinal images  

Microsoft Academic Search

Analysis of retinal blood vessels is extremely important for diagnosis and treatment of many diseases such as diabetic retinopathy, hypertension, glukoma, arteriosclerosis etc. Therefore, especially vessel segmentation is one of the most critical steps for detection and treatment of these diseases. In this paper, Gabor filter and 2D matched filter response methods, which are used to enhance blood vessels, were

Zafer Yavuz; Cemal Köse

2010-01-01

354

Stochastic resonance with matched filtering  

E-print Network

Along with the development of interferometric gravitational wave detector, we enter into an epoch of gravitational wave astronomy, which will open a brand new window for astrophysics to observe our universe. Almost all of the data analysis methods in gravitational wave detection are based on matched filtering. Gravitational wave detection is a typical example of weak signal detection, and this weak signal is buried in strong instrument noise. So it seems attractable if we can take advantage of stochastic resonance. But unfortunately, almost all of the stochastic resonance theory is based on Fourier transformation and has no relation to matched filtering. In this paper we try to relate stochastic resonance to matched filtering. Our results show that stochastic resonance can indeed be combined with matched filtering for both periodic and non-periodic input signal. This encouraging result will be the first step to apply stochastic resonance to matched filtering in gravitational wave detection. In addition, based on matched filtering, we firstly proposed a novel measurement method for stochastic resonance which is valid for both periodic and non-periodic driven signal.

Li-Fang Li; Jian-Yang Zhu

2010-06-28

355

Smoothing filter for digital to analog conversion  

NASA Technical Reports Server (NTRS)

An electronic filter comprised of three active filter sections to smooth the stepped signal from a digital to analog converter is described. The first section has a noninverting low pass filter transfer function, and the second has an inverting transfer function designed to pass a narrow frequency band centered at the step frequency of the stepped output signal with sharp cutoff of either side of that narrow band. The third section adds the noninverted output of the first section to the inverted output of the second section. This third section has a lead-lag transfer function designed to reduce the phase angle between the signal at its output terminal and the stepped signal at the input of the first section.

Wagner, C. A. (inventor)

1981-01-01

356

Analytic study on the effects of the number of MLC segments and the least segment area on step-and-shoot head-and-neck IMRT planning using direct machine parameter optimization  

NASA Astrophysics Data System (ADS)

In this study, we present the concurrent effects of the number of segments (NS) and the least segment area (LSA) for step-and-shoot head-and-neck intensity-modulated radiation therapy (IMRT) planning using the direct machine parameter optimization (DMPO), on which basis we suggest the optimal NS and LSA ranges. We selected three head-and-neck patients who had received IMRT via the simultaneous integrated boost (SIB) technique and classified them as easy, intermediate, and difficult cases. We formulated a benchmark plan and made 11 additional plans by re-optimizing the benchmark by varying the NS and the LSA for each case. Clinical and physical plan-quality evaluation parameters were considered separately: the conformality index (CI), the homogeneity index (HI) and the maximum or mean doses for the organs-at-risk were the clinical factors, and these were summarized as plan-quality parameter, Q. The modulation index (MI), the total monitor units (MUs), and the final composite cost function F were employed as parameters in the evaluation of the physical aspects. A 2-way analysis of variance (2-way ANOVA) was used to determine the effects of the NS and the LSA concurrently. Pearson's correlations among the total MU, MI, F, and Q were examined as well. Overall plan-efficiency factor ? was defined to estimate the optimal NS and LSA by considering the plan's quality and the beam delivery efficiency together. Plans with simple targets or a small number of beams (NB) were affected by the LSA whereas plans with complex targets or large NB were affected by the NS. Moreover, smaller NS and smaller LSA were advantageous for simple plans whereas larger NS and smaller LSA were beneficial for complex plans. When we consider the plan's quality and the beam delivery efficiency, {NS = 60-80, LSA = 8-12 cm2} are the proper ranges for head-and-neck IMRT planning with DMPO; however, the combination may differ based on the complexity of a given plan.

Cheong, Kwang-Ho; Kang, Sei-Kwon; Lee, MeYeon; Kim, Haeyoung; Bae, Hoonsik; Park, SoAh; Hwang, Taejin; Kim, KyoungJu; Han, Taejin

2013-05-01

357

Triple-Quantum Filtered NMR Imaging of Sodium -23 in the Human Brain  

NASA Astrophysics Data System (ADS)

In the past multiple-quantum filtered imaging of biexponential relaxation sodium-23 nuclei in the human brain has been limited by low signal to noise ratios; this thesis demonstrates that such imaging is feasible when using a modified gradient-selected triple-quantum filter at a repetition time which maximizes the signal to noise ratio. Nuclear magnetic resonance imaging of biexponential relaxation sodium-23 (^{23}Na) nuclei in the human brain may be useful for detecting ischemia, cancer, and pathophysiology related to manic-depression. Multiple -quantum filters may be used to selectively image biexponential relaxation ^{23}Na signals since these filters suppress single-exponential relaxation ^{23}Na signals. In this thesis, the typical repetition times (200 -300 ms) used for in vivo multiple-quantum filtered ^{23}Na experiments are shown to be approximately 5 times greater than the optimal repetition time which maximizes multiple-quantum filtered SNR. Calculations and experimental verification show that the gradient-selected triple-quantum (GS3Q) filtered SNR for ^ {23}Na in a 4% agarose gel increases by a factor of two as the repetition time decreases from 300 ms to 55 ms. It is observed that a simple reduction of repetition time also increases spurious single-quantum signals from GS3Q filtered experiments. Irreducible superoperator calculations have been used to design a modified GS3Q filter which more effectively suppresses the spurious single-quantum signals. The modified GS3Q filter includes a preparatory crusher gradient and two-step-phase cycling. Using the modified GS3Q filter and a repetition time of 70 ms, a three dimensional triple-quantum filtered image of a phantom modelling ^{23} Na in the brain was obtained. The phantom consisted of two 4 cm diameter spheres inside of a 8.5 cm x 7 cm ellipsoid. The two spheres contained 0.012 and 0.024 M ^{23}Na in 4% agarose gel. Surrounding the spheres and inside the ellipsoid was 0.03 M aqueous ^{23}Na. The image dimensions were 16 x 16 x 16 voxels with the dimension of a voxel being 1.5 x 1.5 x 1.5 cm^3. The signal to noise ratio for the GS3Q filtered ^ {23}Na signal from the 0.012 and 0.024 M ^{23}Na spheres was 17 and 30 for a 54 minute experiment at 2.35 T. (Abstract shortened by UMI.).

Keltner, John Robinson

358

THE REDUCED RANK TRANSFORM SQUARE ROOT FILTER FOR DATA ASSIMILATION  

E-print Network

. The Kalman filter, well known from linear control theory, is the optimal algorithm for assimilating with the Earth's magnetosphere. 2. THE KALMAN FILTER Consider the linear discrete time model xk+1 = Akxk + Bkuk the number of input variables, n mw, p mu. Under this assumptions, the computation time of the Kalman filter

359

State Estimation Using a Reduced-Order Kalman Filter  

Microsoft Academic Search

Minimizing forecast error requires accurately specifying the initial state from which the forecast is made by optimally using available observing resources to obtain the most accurate possible analysis. The Kalman filter accomplishes this for a wide class of linear systems, and experience shows that the extended Kalman filter also performs well in nonlinear systems. Unfortunately, the Kalman filter and the

Brian F. Farrell; Petros J. Ioannou

2001-01-01

360

Comparison of Cascaded LMS-RLS, LMS and RLS Adaptive Filters in Non-Stationary Environments  

Microsoft Academic Search

\\u000a This paper proposes a cascaded LMS-RLS prediction filter for improved performance in non-stationary environments. In this\\u000a proposed filter, an LMS filter with varying step-size is used as the initial filter for achieving faster convergence rate\\u000a and then a RLS filter for obtaining improved convergence. Theoretical analysis shows that the proposed technique improves\\u000a the behavior of the adaptive filter in steady

Bharath Sridhar; I. Akram Sheriff; K. A. Narayanan Kutty; S. Sathish Kumar

2008-01-01

361

ADVANCED HOT GAS FILTER DEVELOPMENT  

SciTech Connect

DuPont Lanxide Composites, Inc. undertook a sixty-month program, under DOE Contract DEAC21-94MC31214, in order to develop hot gas candle filters from a patented material technology know as PRD-66. The goal of this program was to extend the development of this material as a filter element and fully assess the capability of this technology to meet the needs of Pressurized Fluidized Bed Combustion (PFBC) and Integrated Gasification Combined Cycle (IGCC) power generation systems at commercial scale. The principal objective of Task 3 was to build on the initial PRD-66 filter development, optimize its structure, and evaluate basic material properties relevant to the hot gas filter application. Initially, this consisted of an evaluation of an advanced filament-wound core structure that had been designed to produce an effective bulk filter underneath the barrier filter formed by the outer membrane. The basic material properties to be evaluated (as established by the DOE/METC materials working group) would include mechanical, thermal, and fracture toughness parameters for both new and used material, for the purpose of building a material database consistent with what is being done for the alternative candle filter systems. Task 3 was later expanded to include analysis of PRD-66 candle filters, which had been exposed to actual PFBC conditions, development of an improved membrane, and installation of equipment necessary for the processing of a modified composition. Task 4 would address essential technical issues involving the scale-up of PRD-66 candle filter manufacturing from prototype production to commercial scale manufacturing. The focus would be on capacity (as it affects the ability to deliver commercial order quantities), process specification (as it affects yields, quality, and costs), and manufacturing systems (e.g. QA/QC, materials handling, parts flow, and cost data acquisition). Any filters fabricated during this task would be used for product qualification tests being conducted by Westinghouse at Foster-Wheeler's Pressurized Circulating Fluidized Bed (PCFBC) test facility in Karhula, Finland. Task 5 was designed to demonstrate the improvements implemented in Task 4 by fabricating fifty 1.5-meter hot gas filters. These filters were to be made available for DOE-sponsored field trials at the Power Systems Development Facility (PSDF), operated by Southern Company Services in Wilsonville, Alabama.

E.S. Connolly; G.D. Forsythe

2000-09-30

362

Design of the J-PAS and J-PLUS filter systems  

NASA Astrophysics Data System (ADS)

J-PAS (Javalambre-PAU Astrophysical Survey) is a Spanish-Brazilian collaboration to conduct an innovative photometric survey of more than 8000 square degrees of northern sky using a system of 57 filters, 54 narrow-band (FWHM=13.8 nm) filters continuously populating the spectrum between 370 to 920 nm with 10.0 nm steps, plus 3 broad-band filters. Together with the main J-PAS survey, the collaboration is carrying out J-PLUS (the Javalambre Photometric Local Universe Survey), an all-sky survey using a set of 12 carefully optimized broad- and narrow-band filters that will be used to perform the calibration tasks for the main survey. The J-PAS survey will be carried out using JPCam, a 14-CCD mosaic camera using the new e2v 9.2k-by-9.2k, 10?m pixel detectors, mounted on the JST/T250, a dedicated 2.55-m wide-field telescope at the Observatorio Astrofísico de Javalambre (OAJ) in Teruel, Spain. J-PLUS, on the other hand, will be carried out using a wide field CCD camera (the T80Cam) equipped with a large format STA 1600 CCD (10.5k-by-10.5k, 9?m pixel) and mounted on the JAST/T80, a dedicated 0.83-m wide-field telescope at the OAJ. In both cases, the filters will operate close to, but up-stream from the dewar window in a fast converging optical beam. This optical configuration imposes challenging requirements for the J-PLUS and J-PAS filters, some of them requiring the development of new filter design solutions. This paper describes the main requirements and design strategies for these two sets of filters.

Marín-Franch, A.; Chueca, S.; Moles, M.; Benitez, N.; Taylor, K.; Cepa, J.; Cenarro, A. J.; Cristobal-Hornillos, D.; Ederoclite, A.; Gruel, N.; Hernández-Fuertes, J.; López-Sainz, A.; Luis-Simoes, R.; Rueda-Teruel, F.; Rueda-Teruel, S.; Varela, J.; Yanes-Díaz, A.; Brauneck, U.; Danielou, A.; Dupke, R.; Fernández-Soto, A.; Mendes de Oliveira, C.; Sodré, L.

2012-09-01

363

The Sloan Digital Sky Survey Stripe 82 Imaging Data: Depth-Optimized Co-adds Over 300 Deg^2 in Five Filters  

E-print Network

We present and release co-added images of the Sloan Digital Sky Survey (SDSS) Stripe 82. Stripe 82 covers an area of 300 deg^2 on the Celestial Equator, and has been repeatedly scanned 70-90 times in the ugriz bands by the SDSS imaging survey. By making use of all available data in the SDSS archive, our co-added images are optimized for depth. Input single-epoch frames were properly processed and weighted based on seeing, sky transparency, and background noise before co-addition. The resultant products are co-added science images and their associated weight images that record relative weights at individual pixels. The depths of the co-adds, measured as the 5 sigma detection limits of the aperture (3.2 arcsec diameter) magnitudes for point sources, are roughly 23.9, 25.1, 24.6, 24.1, and 22.8 AB magnitudes in the five bands, respectively. They are 1.9-2.2 mag deeper than the best SDSS single-epoch data. The co-added images have good image quality, with an average point-spread function FWHM of ~1 arcsec in the ...

Jiang, Linhua; Bian, Fuyan; McGreer, Ian D; Strauss, Michael A; Annis, James; Buck, Zoe; Green, Richard; Hodge, Jacqueline A; Myers, Adam D; Rafiee, Alireza; Richards, Gordon

2014-01-01

364

An online novel adaptive filter for denoising time series measurements.  

PubMed

A nonstationary form of the Wiener filter based on a principal components analysis is described for filtering time series data possibly derived from noisy instrumentation. The theory of the filter is developed, implementation details are presented and two examples are given. The filter operates online, approximating the maximum a posteriori optimal Bayes reconstruction of a signal with arbitrarily distributed and non stationary statistics. PMID:16649562

Willis, Andrew J

2006-04-01

365

Optical ranked-order filtering using threshold decomposition  

DOEpatents

A hybrid optical/electronic system performs median filtering and related ranked-order operations using threshold decomposition to encode the image. Threshold decomposition transforms the nonlinear neighborhood ranking operation into a linear space-invariant filtering step followed by a point-to-point threshold comparison step. Spatial multiplexing allows parallel processing of all the threshold components as well as recombination by a second linear, space-invariant filtering step. An incoherent optical correlation system performs the linear filtering, using a magneto-optic spatial light modulator as the input device and a computer-generated hologram in the filter plane. Thresholding is done electronically. By adjusting the value of the threshold, the same architecture is used to perform median, minimum, and maximum filtering of images. A totally optical system is also disclosed.

Allebach, Jan P. (West Lafayette, IN); Ochoa, Ellen (Pleasanton, CA); Sweeney, Donald W. (Alamo, CA)

1990-01-01

366

Optical ranked-order filtering using threshold decomposition  

DOEpatents

A hybrid optical/electronic system performs median filtering and related ranked-order operations using threshold decomposition to encode the image. Threshold decomposition transforms the nonlinear neighborhood ranking operation into a linear space-invariant filtering step followed by a point-to-point threshold comparison step. Spatial multiplexing allows parallel processing of all the threshold components as well as recombination by a second linear, space-invariant filtering step. An incoherent optical correlation system performs the linear filtering, using a magneto-optic spatial light modulator as the input device and a computer-generated hologram in the filter plane. Thresholding is done electronically. By adjusting the value of the threshold, the same architecture is used to perform median, minimum, and maximum filtering of images. A totally optical system is also disclosed. 3 figs.

Allebach, J.P.; Ochoa, E.; Sweeney, D.W.

1987-10-09

367

Feasibility of nanofluid-based optical filters.  

PubMed

In this article we report recent modeling and design work indicating that mixtures of nanoparticles in liquids can be used as an alternative to conventional optical filters. The major motivation for creating liquid optical filters is that they can be pumped in and out of a system to meet transient needs in an application. To demonstrate the versatility of this new class of filters, we present the design of nanofluids for use as long-pass, short-pass, and bandpass optical filters using a simple Monte Carlo optimization procedure. With relatively simple mixtures, we achieve filters with <15% mean-squared deviation in transmittance from conventional filters. We also discuss the current commercial feasibility of nanofluid-based optical filters by including an estimation of today's off-the-shelf cost of the materials. While the limited availability of quality commercial nanoparticles makes it hard to compete with conventional filters, new synthesis methods and economies of scale could enable nanofluid-based optical filters in the near future. As such, this study lays the groundwork for creating a new class of selective optical filters for a wide range of applications, namely communications, electronics, optical sensors, lighting, photography, medicine, and many more. PMID:23458793

Taylor, Robert A; Otanicar, Todd P; Herukerrupu, Yasitha; Bremond, Fabienne; Rosengarten, Gary; Hawkes, Evatt R; Jiang, Xuchuan; Coulombe, Sylvain

2013-03-01

368

The Sloan Digital Sky Survey Stripe 82 Imaging Data: Depth-optimized Co-adds over 300 deg2 in Five Filters  

NASA Astrophysics Data System (ADS)

We present and release co-added images of the Sloan Digital Sky Survey (SDSS) Stripe 82. Stripe 82 covers an area of ~300 deg2 on the celestial equator, and has been repeatedly scanned 70-90 times in the ugriz bands by the SDSS imaging survey. By making use of all available data in the SDSS archive, our co-added images are optimized for depth. Input single-epoch frames were properly processed and weighted based on seeing, sky transparency, and background noise before co-addition. The resultant products are co-added science images and their associated weight images that record relative weights at individual pixels. The depths of the co-adds, measured as the 5? detection limits of the aperture (3.''2 diameter) magnitudes for point sources, are roughly 23.9, 25.1, 24.6, 24.1, and 22.8 AB magnitudes in the five bands, respectively. They are 1.9-2.2 mag deeper than the best SDSS single-epoch data. The co-added images have good image quality, with an average point-spread function FWHM of ~1'' in the r, i, and z bands. We also release object catalogs that were made with SExtractor. These co-added products have many potential uses for studies of galaxies, quasars, and Galactic structure. We further present and release near-IR J-band images that cover ~90 deg2 of Stripe 82. These images were obtained using the NEWFIRM camera on the NOAO 4 m Mayall telescope, and have a depth of about 20.0-20.5 Vega magnitudes (also 5? detection limits for point sources).

Jiang, Linhua; Fan, Xiaohui; Bian, Fuyan; McGreer, Ian D.; Strauss, Michael A.; Annis, James; Buck, Zoë; Green, Richard; Hodge, Jacqueline A.; Myers, Adam D.; Rafiee, Alireza; Richards, Gordon

2014-07-01

369

Conjugate linear filtering  

Microsoft Academic Search

Aspects of optimum filtering for complex valued random processes are presented. Ordinary linear filters are complemented with conjugate linear filters. It is found that the incorporation of conjugate linear filtering improves signal-to-noise ratio by a factor of two in matched filter receivers. For optimum least squares filtering the inclusion of conjugate processing reduces mean-square error by a factor as great

W. Brown; R. Crane

1969-01-01

370

Filtering through combination of positive filters  

Microsoft Academic Search

The linear filters characterized by a state-variable realization given by matrices with nonnegative entries (called positive filters) are heavily restricted in their achievable performance. Nevertheless, such filters are the only choice when dealing with the charged coupled device MOS technology of charge routing networks (CRN's), since nonnegativity is a consequence of the underlying physical mechanism. In order to exploit the

Luca Benvenuti; Lorenzo Farina; Brian D. O. Anderson

1999-01-01

371

3D early embryogenesis image filtering by nonlinear partial differential equations.  

PubMed

We present nonlinear diffusion equations, numerical schemes to solve them and their application for filtering 3D images obtained from laser scanning microscopy (LSM) of living zebrafish embryos, with a goal to identify the optimal filtering method and its parameters. In the large scale applications dealing with analysis of 3D+time embryogenesis images, an important objective is a correct detection of the number and position of cell nuclei yielding the spatio-temporal cell lineage tree of embryogenesis. The filtering is the first and necessary step of the image analysis chain and must lead to correct results, removing the noise, sharpening the nuclei edges and correcting the acquisition errors related to spuriously connected subregions. In this paper we study such properties for the regularized Perona-Malik model and for the generalized mean curvature flow equations in the level-set formulation. A comparison with other nonlinear diffusion filters, like tensor anisotropic diffusion and Beltrami flow, is also included. All numerical schemes are based on the same discretization principles, i.e. finite volume method in space and semi-implicit scheme in time, for solving nonlinear partial differential equations. These numerical schemes are unconditionally stable, fast and naturally parallelizable. The filtering results are evaluated and compared first using the Mean Hausdorff distance between a gold standard and different isosurfaces of original and filtered data. Then, the number of isosurface connected components in a region of interest (ROI) detected in original and after the filtering is compared with the corresponding correct number of nuclei in the gold standard. Such analysis proves the robustness and reliability of the edge preserving nonlinear diffusion filtering for this type of data and lead to finding the optimal filtering parameters for the studied models and numerical schemes. Further comparisons consist in ability of splitting the very close objects which are artificially connected due to acquisition error intrinsically linked to physics of LSM. In all studied aspects it turned out that the nonlinear diffusion filter which is called geodesic mean curvature flow (GMCF) has the best performance. PMID:20457535

Krivá, Z; Mikula, K; Peyriéras, N; Rizzi, B; Sarti, A; Stasová, O

2010-08-01

372

Ceramic-fiber ceramic-matrix hot-gas filters  

SciTech Connect

This program is currently developing a process for the fabrication of ceramic composite filter specimens by chemical vapor deposition. A process for the fabrication of dense ceramic composites is being modified to produce low density filter specimens. The process modifications include elimination of the thermal gradient across the fibrous preform and the control of the porosity distribution to produce a composite suitable for high-temperature filter applications. The configuration of the filter specimens (fiber composition and porosity distribution, composition of deposited material, filter design, etc.) will be investigated to optimize filter efficiency, cleanability, strength, toughness, and chemical compatibility. Filter specimens of the optimum configuration will then be fabricated in tubular shapes for candle filter applications. Corrugated fabrics will be utilized to increase the available surface area of the candle filter. 5 refs., 7 figs.

Stinton, D.P.; Chang, R.

1987-06-01

373

Inverse Variation: Step By Step Lesson  

NSDL National Science Digital Library

This step by step lesson from the Math Ops website explains inverse variation. Students can read the text or follow along as it is read out loud. The lesson includes nine slides which explain what an inverse variation equation is, and include several real world examples of this type of mathematical model.

2012-01-01

374

Step graded buffer for (110) InSb quantum wells grown by molecular beam epitaxy  

NASA Astrophysics Data System (ADS)

We report on a two step buffer layer preparation for the growth of InSb quantum wells on a (110) GaAs surface. At each buffer layer step, layer conditions were optimized to produce smooth surfaces compatible with InSb quantum wells. Through varying growth rate, group V/III flux ratio, substrate temperature, and the addition of in situ annealing, we are able to grow In0.85Al0.15Sb on a GaAs substrate with an RMS surface roughness of approximately 2 nm. Surface morphology and cross-sectional transmission electron microscopy (TEM) were analyzed to understand the formation of threading dislocations, inclusions and dislocation filtering. This work presents an initial study for the growth of large lattice mismatched III-V materials on the (110) surface.

Podpirka, Adrian A.; Twigg, Mark E.; Tischler, Joseph G.; Magno, Richard; Bennett, Brian R.

2014-10-01

375

Stepping motor controller  

DOEpatents

A stepping motor is microprocessingly controlled by digital circuitry which monitors the output of a shaft encoder adjustably secured to the stepping motor and generates a subsequent stepping pulse only after the preceding step has occurred and a fixed delay has expired. The fixed delay is variable on a real-time basis to provide for smooth and controlled deceleration.

Bourret, Steven C. (Los Alamos, NM); Swansen, James E. (Los Alamos, NM)

1984-01-01

376

Stepping motor controller  

DOEpatents

A stepping motor is microprocessor controlled by digital circuitry which monitors the output of a shaft encoder adjustably secured to the stepping motor and generates a subsequent stepping pulse only after the preceding step has occurred and a fixed delay has expired. The fixed delay is variable on a real-time basis to provide for smooth and controlled deceleration.

Bourret, S.C.; Swansen, J.E.

1982-07-02

377

An improved matched filter for blood vessel detection of digital retinal images  

Microsoft Academic Search

The matched filter has been widely used in the detection of blood vessels of the human retina digital image. In this paper, the matched filter response to the detection of blood vessels is increased by proposing better filter parameters. These filter parameters are found by using an optimization procedure on 20 retina images of the DRIVE database. Comparisons with other

Mohammed Al-Rawi; Munib Qutaishat; Mohammed Arrar

2007-01-01

378

Allpass filter design with waveguide loss compensation.  

PubMed

A major artifact of realistic photonic filters is the waveguide power loss. Its detrimental effect on the allpass structure is particularly alarming because the phase response is highly sensitive to perturbations. While the loss can be simply captured into a variation on the unit delay in signal processing analysis, its non-linearity makes it mathematically difficult to address. We present an allpass filter design algorithm that is able to provide filter coefficients that compensate for the waveguide power loss. By absorbing the loss parameter into the design cost function, the optimization problem becomes non-convex and NP hard. Our approach solves this problem by utilizing an iterative algorithm in conjunction with the branch and bound global optimization technique. The proposed algorithm is expected to improve the performance and increase the utilization of allpass filters for optical signal phase based applications such as distortion compensation and group delay equalization. PMID:24514799

Wang, Yujia; Grieco, Andrew; Nguyen, Truong

2013-12-30

379

Motion filter vector quantization  

Microsoft Academic Search

Motion-compensated prediction of video is formulated as a novel vector quantization scheme called motion filter vector quantiza- tion (MFVQ). In MFVQ, the motion vector and the pixel-intensity interpolation filter are combined into a motion filter and the en- tire filter is vector quantized. A codebook design algorithm is proposed for designing unit gain and entropy constrained MFVQ codebooks. The algorithm

Dariusz Blasiak; Wai-yip Chan

2002-01-01

380

Recirculating electric air filter  

DOEpatents

An electric air filter cartridge has a cylindrical inner high voltage eleode, a layer of filter material, and an outer ground electrode formed of a plurality of segments moveably connected together. The outer electrode can be easily opened to remove or insert filter material. Air flows through the two electrodes and the filter material and is exhausted from the center of the inner electrode.

Bergman, Werner (Pleasanton, CA)

1986-01-01

381

Hepa filter dissolution process  

DOEpatents

A process for dissolution of spent high efficiency particulate air (HEPA) filters and then combining the complexed filter solution with other radioactive wastes prior to calcining the mixed and blended waste feed. The process is an alternate to a prior method of acid leaching the spent filters which is an inefficient method of treating spent HEPA filters for disposal.

Brewer, Ken N. (Arco, ID); Murphy, James A. (Idaho Falls, ID)

1994-01-01

382

HEPA filter dissolution process  

SciTech Connect

This invention is comprised of a process for dissolution of spent high efficiency particulate air (HEPA) filters and then combining the complexed filter solution with other radioactive wastes prior to calcining the mixed and blended waste feed. The process is an alternate to a prior method of acid leaching the spent filters which is an inefficient method of treating spent HEPA filters for disposal.

Brewer, K.N.; Murphy, J.A.

1992-12-31

383

Recirculating electric air filter  

DOEpatents

An electric air filter cartridge has a cylindrical inner high voltage electrode, a layer of filter material, and an outer ground electrode formed of a plurality of segments moveably connected together. The outer electrode can be easily opened to remove or insert filter material. Air flows through the two electrodes and the filter material and is exhausted from the center of the inner electrode.

Bergman, W.

1985-01-09

384

HEPA filter dissolution process  

DOEpatents

A process is described for dissolution of spent high efficiency particulate air (HEPA) filters and then combining the complexed filter solution with other radioactive wastes prior to calcining the mixed and blended waste feed. The process is an alternate to a prior method of acid leaching the spent filters which is an inefficient method of treating spent HEPA filters for disposal. 4 figures.

Brewer, K.N.; Murphy, J.A.

1994-02-22

385

A FILTER METHOD WITH UNIFIED STEP COMPUTATION FOR ...  

E-print Network

readily scale-up to problems involving millions of variables. Their main ... a single function, whereby their individual perceived importance is determined by a weighting parameter. The quality of ..... We stress that the updated point xk+1 is.

2013-05-09

386

Effects of electron beam irradiation of cellulose acetate cigarette filters  

NASA Astrophysics Data System (ADS)

A method to reduce the molecular weight of cellulose acetate used in cigarette filters by using electron beam irradiation is demonstrated. Radiation levels easily obtained with commercially available electron accelerators result in a decrease in average molecular weight of about six-times with no embrittlement, or significant change in the elastic behavior of the filter. Since a first step in the biodegradation of cigarette filters is reduction in the filter material's molecular weight this invention has the potential to allow the production of significantly faster degrading filters.

Czayka, M.; Fisch, M.

2012-07-01

387

An adaptive optical filter based on thermo-optic (TO) polymeric waveguide lattice filters  

NASA Astrophysics Data System (ADS)

An adaptive optical filter based on novel thermo-optic polymeric waveguide lattice filters is proposed. Unlike conventional interference or resonance based optical filter, the adaptive filter is based on thermo-optic two-port waveguide lattice filters, which can greatly reduce the size, complexity and considerably increase the tuning range of an optical filter. By employing integrated variable optical attenuators (VOA), which functioned as the dynamically reconfigurable filter coefficients, the profile of the filter can be dynamically controlled. The classical frequency sampling and step down recursion algorithms are used for the synthesis of the VOA filter coefficients. Simulation and preliminary experimental results show that a tuning range of 50nm can be realized with filter extinction ration of ~40dB. The larger tunaing range comes from the larger by thermo-optic (TO) coefficients of polymer materials. Since it is based on polymeric waveguides, this device can be easily integrated with other polymer waveguide devices such as optical switches, EO modulators, and thus form a building block for photonic intergrated circuits.

Lu, Xuejun

2004-06-01

388

An Introduction to PALM: Filtering Filter methods  

E-print Network

for scalar variables: t = - (ui) xi ´ The filtering process yields non-linear terms, e.g. ujui, ´ In order for these equations to be usable the non-linear terms (e.g., ujui) have to be expressed as a function of the filtered quantities (e.g., ui) and of sub-filter scales (ui) (decomposing the non-linear terms) #12;4 (10) Decomposing

Raasch, Siegfried

389

Application of an Optimal Tuner Selection Approach for On-Board Self-Tuning Engine Models  

NASA Technical Reports Server (NTRS)

An enhanced design methodology for minimizing the error in on-line Kalman filter-based aircraft engine performance estimation applications is presented in this paper. It specific-ally addresses the under-determined estimation problem, in which there are more unknown parameters than available sensor measurements. This work builds upon an existing technique for systematically selecting a model tuning parameter vector of appropriate dimension to enable estimation by a Kalman filter, while minimizing the estimation error in the parameters of interest. While the existing technique was optimized for open-loop engine operation at a fixed design point, in this paper an alternative formulation is presented that enables the technique to be optimized for an engine operating under closed-loop control throughout the flight envelope. The theoretical Kalman filter mean squared estimation error at a steady-state closed-loop operating point is derived, and the tuner selection approach applied to minimize this error is discussed. A technique for constructing a globally optimal tuning parameter vector, which enables full-envelope application of the technology, is also presented, along with design steps for adjusting the dynamic response of the Kalman filter state estimates. Results from the application of the technique to linear and nonlinear aircraft engine simulations are presented and compared to the conventional approach of tuner selection. The new methodology is shown to yield a significant improvement in on-line Kalman filter estimation accuracy.

Simon, Donald L.; Armstrong, Jeffrey B.; Garg, Sanjay

2012-01-01

390

Flat microwave photonic filter based on hybrid of two filters  

NASA Astrophysics Data System (ADS)

A new microwave photonic filter (MPF) hybrid of two filters that can realize both multiple taps and a flat bandpass or bandstop response is presented. Based on the phase character of a Mach-Zehnder modulator (MZM), a two taps finite impulse response (FIR) filter is obtained as the first part. The second part is obtained by taking full advantage of the wavelength selectivity of the fiber Bragg grating (FBG) and the gain of a erbium-doped fiber (EDF). Combining the two filters, the flat bandpass or bandstop response is realized by changing the coupler's factor k, the reflectivity of FBG1 R1 or the gain of the EDF g. Optimizing the system parameters, a flat bandpass response with amplitude depth of more than 45 dB is obtained at k = 0.5, R1 = 0.33, g = 10, and a flat bandstop response is also obtained at k = 0.4, R1 = 0.5, g = 2. In addition, the free-spectral range (FSR) can be controlled by changing the length of the EDF and the length difference between two MZMs. The method is proved feasible by some experiments. Such a method offers realistic solutions to support future radio-frequency (RF) optical communication systems.

Qi, Chunhui; Pei, Li; Ning, Tigang; Li, Jing; Gao, Song

2010-05-01

391

Lightning Leader Stepping  

NASA Astrophysics Data System (ADS)

Recent measurements may help explain the uneven propagation, or stepping, of lightning leaders. Measurements of the electric vector vs. time near a negative lightning leader show that each step forward is accompanied by a wave that moves backward along the ionized channel. This backward-moving wave---which could be called a "step recoil wave"--- rapidly transfers charge and energy from the existing ionized channel to the channel segment created by the new step. The transfer of charge and energy from the existing channel into the new step implies a reduction of the channel potential energy. The potential energy of the new step is further reduced as it produces excited molecules and ion-electron pairs. Eventually the new step stops. A current from the original source of charge for the leader increases the potential energy of the channel until another step is initiated.

Winn, W. P.

2010-12-01

392

Rigid porous filter  

DOEpatents

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

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

2000-01-01

393

Crowdsourcing step-by-step information extraction to enhance existing how-to videos  

E-print Network

Millions of learners today use how-to videos to master new skills in a variety of domains. But browsing such videos is often tedious and inefficient because video player interfaces are not optimized for the unique step-by-step ...

Nguyen, Phu Tran

394

Reduction of turbidity by a coal-aluminium filter  

SciTech Connect

Coal-aluminium granular filters successfully reduce turbidity in low-alkalinity raw waters to less than 1.0 ntu, without a coagulation step or external coagulant aids. Data from experiments conducted with control and pilot-plant filters show the viability of the process and indicate the turbidity and retention mechanisms. Operational characteristics of the process are similar to those of a conventional filter. The costs of the coal-aluminium process compare favourably with those of traditional treatment.

Collins, A.G.; Johnson, R.L.

1985-06-01

395

Fuzzy adaptive filters, with application to nonlinear channel equalization  

Microsoft Academic Search

Two fuzzy adaptive filters are developed: one uses a recursive-least-squares (RLS) adaptation algorithm, and the other uses a least-mean-square (LMS) adaptation algorithm. The RLS fuzzy adaptive filter is constructed through the following four steps: (1) define fuzzy sets in the filter input space Rn whose membership functions cover U; (2) construct a set of fuzzy IF-THEN rules which either come

Li-Xin Wang; Jerry M. Mendel

1993-01-01

396

Software Would Largely Automate Design of Kalman Filter  

NASA Technical Reports Server (NTRS)

Embedded Navigation Filter Automatic Designer (ENFAD) is a computer program being developed to automate the most difficult tasks in designing embedded software to implement a Kalman filter in a navigation system. The most difficult tasks are selection of error states of the filter and tuning of filter parameters, which are timeconsuming trial-and-error tasks that require expertise and rarely yield optimum results. An optimum selection of error states and filter parameters depends on navigation-sensor and vehicle characteristics, and on filter processing time. ENFAD would include a simulation module that would incorporate all possible error states with respect to a given set of vehicle and sensor characteristics. The first of two iterative optimization loops would vary the selection of error states until the best filter performance was achieved in Monte Carlo simulations. For a fixed selection of error states, the second loop would vary the filter parameter values until an optimal performance value was obtained. Design constraints would be satisfied in the optimization loops. Users would supply vehicle and sensor test data that would be used to refine digital models in ENFAD. Filter processing time and filter accuracy would be computed by ENFAD.

Chuang, Jason C. H.; Negast, William J.

2005-01-01

397

Solving Single Step Equations  

NSDL National Science Digital Library

This is to practice and review single step equations. Have fun. Complete the following two sites. Follow the directions given for each site. One-Step Equations Add/Subtract One-Step Equations Mult/Division When you have finished the sites above, enter equation buster and work through level one. Equation buster ...

Reddish, Ms.

2011-09-30

398

A Step Circuit Program.  

ERIC Educational Resources Information Center

Aerobics instructors can use step aerobics to motivate students. One creative method is to add the step to the circuit workout. By incorporating the step, aerobic instructors can accommodate various fitness levels. The article explains necessary equipment and procedures, describing sample stations for cardiorespiratory fitness, muscular strength,…

Herman, Susan

1995-01-01

399

Filter type gas sampler with filter consolidation  

DOEpatents

Disclosed is an apparatus for automatically consolidating a filter or, more specifically, an apparatus for drawing a volume of gas through a plurality of sections of a filter, whereafter the sections are subsequently combined for the purpose of simultaneously interrogating the sections to detect the presence of a contaminant.

Miley, Harry S. (219 Rockwood Dr., Richland, WA 99352); Thompson, Robert C. (5313 Phoebe La., West Richland, WA 99352); Hubbard, Charles W. (1900 Stevens, Apt. 526, Richland, WA 99352); Perkins, Richard W. (1413 Sunset, Richland, WA 99352)

1997-01-01

400

Filter type gas sampler with filter consolidation  

DOEpatents

Disclosed is an apparatus for automatically consolidating a filter or, more specifically, an apparatus for drawing a volume of gas through a plurality of sections of a filter, where after the sections are subsequently combined for the purpose of simultaneously interrogating the sections to detect the presence of a contaminant. 5 figs.

Miley, H.S.; Thompson, R.C.; Hubbard, C.W.; Perkins, R.W.

1997-03-25

401

Iris Recognition Based on Multichannel Gabor Filtering  

Microsoft Academic Search

A new approach for personal identification based on iris recognition is presented in this paper. The body of this paper details the steps of iris recognition, including image preprocessing, feature extraction and classifier design. The proposed algorithm uses a bank of Gabor filters to capture both local and global iris characteristics to form a fixed length feature vector. Iris matching

Li Ma; Yunhong Wang; Tieniu Tan

402

Iris Recognition Based on Multichannel Gabor Filter  

Microsoft Academic Search

Abstract Anew approach for personal identification based on iris recognition is presented in this paper. The body of this paper details the steps of iris recognition, including image preprocessing, feature extraction and classifier design. The proposed algorithm uses a bank ,of Gabor filters to capture ,both ,local and ,global iris characteristics to form a fixed length feature vector. Iris matching

L. Ma; Y. Wang; T. Tan

2002-01-01

403

Cordierite silicon nitride filters  

SciTech Connect

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

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

1992-02-01

404

Results on principal component filter banks: Colored noise suppression and existence issues  

Microsoft Academic Search

We have recently made explicit the precise connec- tion between the optimization of orthonormal filter banks (FBs) and the principal component property: The principal component filter bank (PCFB) is optimal whenever the minimization objective is a concave function of the subband variances of the FB. This ex- plains PCFB optimality for compression, progressive transmission, and various hitherto unnoticed white-noise suppression

Sony Akkarakaran; P. P. Vaidyanathan

2001-01-01

405

STEP: A Futurevision, Today  

NASA Technical Reports Server (NTRS)

STEP (STandard for the Exchange of Product Model Data) is an innovative software tool that allows the exchange of data between different programming systems to occur and helps speed up the designing in various process industries. This exchange occurs easily between those companies that have STEP, and many industries and government agencies are requiring that their vendors utilize STEP in their computer aided design projects, such as in the areas of mechanical, aeronautical, and electrical engineering. STEP allows the process of concurrent engineering to occur and increases the quality of the design product. One example of the STEP program is the Boeing 777, the first paperless airplane.

1994-01-01

406

Filtering reprecipitated slurry.  

National Technical Information Service (NTIS)

As part of the Late Washing Demonstration at Savannah River Technology Center, Interim Waste Technology has filtered reprecipitated and non reprecipitated slurry with the Experimental Laboratory Filter (ELF) at TNX. Reprecipitated slurry generates higher ...

M. F. Morrissey

1992-01-01

407

In Defense of Filtering.  

ERIC Educational Resources Information Center

Presents responses to 10 common arguments against the use of Internet filters in libraries. Highlights include keyword blocking; selection of materials; liability of libraries using filters; users' judgments; Constitutional issues, including First Amendment rights; and censorship. (LRW)

Burt, David

1997-01-01

408

Novel Backup Filter Device for Candle Filters  

SciTech Connect

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

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

2002-09-18

409

Earth Water Filter  

NSDL National Science Digital Library

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

410

Survey of digital filtering  

NASA Technical Reports Server (NTRS)

A three part survey is made of the state-of-the-art in digital filtering. Part one presents background material including sampled data transformations and the discrete Fourier transform. Part two, digital filter theory, gives an in-depth coverage of filter categories, transfer function synthesis, quantization and other nonlinear errors, filter structures and computer aided design. Part three presents hardware mechanization techniques. Implementations by general purpose, mini-, and special-purpose computers are presented.

Nagle, H. T., Jr.

1972-01-01

411

Infrared-Cut Filter  

Microsoft Academic Search

An infrared-cut filter for TV and video cameras was calculated and fabricated. The filter contains 29 alternating SiO2 and TiO2 layers. A real filter has a transmittance of 90% in the 400-650 nm range and 1% in the 700-1000 nm range.

Leonid Berezhinsky; Kwang-Ho Kwon; Byung-Sun Park

2001-01-01

412

Electronically tuneable light filter  

Microsoft Academic Search

This paper presents an electronically tuneable light filter. The filter can separate a very narrow band of light in an electronically controlled manner. The separated band of light is focused as an image. The filter can work as a very fast shutter too. A speed of that shutter can reach 1 microsecond or better. The term 'light' is understood herein

Kazimierz S. Holubowicz

1990-01-01

413

HEPA filter encapsulation  

DOEpatents

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

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

2003-01-01

414

Practical Active Capacitor Filter  

NASA Technical Reports Server (NTRS)

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

Shuler, Robert L., Jr. (Inventor)

2005-01-01

415

Wavelet domain filtering for photon imaging systems  

NASA Astrophysics Data System (ADS)

Many imaging systems rely on photon detection as the basis of image formation. One of the major sources of error in these systems is Poisson noise due to the quantum nature of the photon detection process. Unlike additive Gaussian noise, Poisson noise is signal-dependent, and consequently separating signal from noise is a very difficult task. In this paper, we develop a novel wavelet-domain filtering procedure for noise removal in photon imaging systems. The filter adapts to both the signal and the noise and balances the trade-off between noise removal and excessive smoothing of image details. Designed using the statistical method of cross-validation, the filter is simultaneously optimal in a small-sample predictive sum of squares sense and asymptotically optimal in the mean square error sense. The filtering procedure has a simple interpretation as a joint edge detection/estimation process. Moreover, we derive an efficient algorithm for performing the filtering that has the same order of complexity as the fast wavelet transform itself. The performance of the new filter is assessed with simulated data experiments and tested with actual nuclear medicine imagery.

Nowak, Robert D.; Baraniuk, Richard G.

1997-10-01

416

Design-Filter Selection for H2 Control of Microgravity Isolation Systems: A Single-Degree-of-Freedom Case Study  

NASA Technical Reports Server (NTRS)

Many microgravity space-science experiments require active vibration isolation, to attain suitably low levels of background acceleration for useful experimental results. The design of state-space controllers by optimal control methods requires judicious choices of frequency-weighting design filters. Kinematic coupling among states greatly clouds designer intuition in the choices of these filters, and the masking effects of the state observations cloud the process further. Recent research into the practical application of H2 synthesis methods to such problems, indicates that certain steps can lead to state frequency-weighting design-filter choices with substantially improved promise of usefulness, even in the face of these difficulties. In choosing these filters on the states, one considers their relationships to corresponding design filters on appropriate pseudo-sensitivity- and pseudo-complementary-sensitivity functions. This paper investigates the application of these considerations to a single-degree-of-freedom microgravity vibration-isolation test case. Significant observations that were noted during the design process are presented. along with explanations based on the existent theory for such problems.

Hampton, R. David; Whorton, Mark S.

2000-01-01

417

Adaptive Filter and Morphological Operators Using Binary PSO  

Microsoft Academic Search

\\u000a Mathematical morphology is a tool for processing shapes in image processing. Adaptively finding the specific morphological\\u000a filter is an important and challenging task in morphological image processing. In order to model the filter and filtering\\u000a sequence for morphological operations adaptively, a novel technique based on binary particle swarm optimization (BPSO) is\\u000a proposed. BPSO is a discrete PSO, where the components

Muhammad Sharif; Mohsin Bilal; Salabat Khan; M. Arfan Jaffar

2010-01-01

418

Optimization of material, design, and operational parameters associated with full-scale 400,000-acfm fabic filter baghouse on the City of Colorado Springs' Martin Drake Generating Unit No. 6  

Microsoft Academic Search

A program for determining the optimum design, construction, and operation of a fabric filter baghouse for control flyash emissions from a Colorado power plant fueled with low-sulfur coal is described. The primary purposes of this program were to show that fabric filter system can be designed on scientific principles rather than rule-of-thumb methods and that the operation of such a

R. L. Ostop; L. A. Thaxton

1978-01-01

419

MANUSCRIPT 1 Bayesian Filtering: From Kalman Filters to  

E-print Network

of Bayesian filtering as well as its rich leaves in the literature. Stochastic filtering theory is briefly filtering are also explored. Index Terms-- Stochastic filtering, Bayesian filtering, Bayesian inference . . . . . . . . . . . . . . 4 II-D Nonlinear Stochastic Filtering Is an Ill-posed Inverse Problem

Chisci, Luigi

420

Regenerative particulate filter development  

NASA Technical Reports Server (NTRS)

Development, design, and fabrication of a prototype filter regeneration unit for regenerating clean fluid particle filter elements by using a backflush/jet impingement technique are reported. Development tests were also conducted on a vortex particle separator designed for use in zero gravity environment. A maintainable filter was designed, fabricated and tested that allows filter element replacement without any leakage or spillage of system fluid. Also described are spacecraft fluid system design and filter maintenance techniques with respect to inflight maintenance for the space shuttle and space station.

Descamp, V. A.; Boex, M. W.; Hussey, M. W.; Larson, T. P.

1972-01-01

421

Information Barriers for Noisy Lagrangian Tracers in Filtering Random Incompressible Flows  

E-print Network

analytic formulas for the optimal filter for the velocity field involving Riccati equations with random in measuring noisy Lagrangian tracers, have mathematical structure with exact closed analytic formulas

Majda, Andrew J.

422

On the Verification of Synthesized Kalman Filters Ruben Gamboa  

E-print Network

Filter is one of these techniques, and it is applicable when the variable of interest x changes linearly over time and the observable variable z is a linear function of x. Such systems can be described). In this view, the Kalman Filter weighs these two estimates in order to find an optimal (linear) estimate of xt

Gamboa, Ruben

423

Rhombic Silver Nanoparticles Array-Based Plasmonic Filter  

Microsoft Academic Search

A plasmonic filter applied in visible regime is proposed. A method using discrete dipole approximation (DDA) to aid design parameters of rhombic Ag nanoparticle array is adopted for the filter design and optimization on the basis of computational numerical calculation. Influence of the particle parameters such as thickness, period and effective index of medium around the particles on the extinction

Yongqi Fu; Shaoli Zhu; Xiuli Zhou; Wei Zhou; Wei Zhao

2011-01-01

424

Fast Kalman filtering on quasilinear dendritic trees Liam Paninski  

E-print Network

Fast Kalman filtering on quasilinear dendritic trees Liam Paninski Department of Statistics, 2009 Abstract Optimal filtering of noisy voltage signals on dendritic trees is a key problem in compu the sparse tree structure of dendritic dynamics. The resulting methods give a very good approxima- tion

Columbia University

425

Birefringent filter design by use of a modified genetic algorithm  

E-print Network

Birefringent filter design by use of a modified genetic algorithm Mengtao Wen and Jianping Yao A modified genetic algorithm is proposed for the optimization of fiber birefringent filters. The orientation angles and the element lengths are determined by the genetic algorithm to minimize the sidelobe levels

Yao, Jianping

426

Ceramic fiber filter technology  

SciTech Connect

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

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

1996-06-01

427

INEEL HEPA Filter Leach System: A Mixed Waste Solution  

SciTech Connect

Calciner operations and the fuel dissolution process at the Idaho National Engineering and Environmental Laboratory have generated many mixed waste high-efficiency particulate air (HEPA) filters. The HEPA Filter Leach System located at the Idaho Nuclear Technology and Engineering Center lowers radiation contamination levels and reduces cadmium, chromium, and mercury concentrations on spent HEPA filter media to below disposal limits set by the Resource Conservation and Recovery Act (RCRA). The treated HEPA filters are disposed as low-level radioactive waste. The technical basis for the existing system was established and optimized in initial studies using simulants in 1992. The treatment concept was validated for EPA approval in 1994 by leaching six New Waste Calcining Facility spent HEPA filters. Post-leach filter media sampling results for all six filters showed that both hazardous and radiological constituent levels were reduced so the filters could be disposed of as low-level radioactive waste. Since the validation tests the HEPA Filter Leach System has processed 78 filters in 1997 and 1998. The Idaho National Engineering and Environmental Laboratory HEPA Filter Leach System is the only mixed waste HEPA treatment system in the DOE complex. This process is of interest to many of the other DOE facilities and commercial companies that have generated mixed waste HEPA filters but currently do not have a treatment option available.

Argyle, Mark Don; Demmer, Ricky Lynn; Archibald, Kip Ernest; Brewer, Ken Neal; Pierson, Kenneth Alan; Shackelford, Kimberlee Rene; Kline, Kelli Suzanne

1999-03-01

428

INEEL HEPA Filter Leach System: A Mixed Waste Solution  

SciTech Connect

Calciner operations and the fuel dissolution process at the Idaho National Engineering and Environmental Laboratory have generated many mixed waste high-efficiency particulate air (HEPA)filters. The HEPA Filter Leach System located at the Idaho Nuclear Technology and Engineering Center lowers radiation contamination levels and reduces cadmium, chromium, and mercury concentrations on spent HEPA filter media to below disposal limits set by the Resource Conservation and Recovery Act (RCRA). The treated HEPA filters are disposed as low-level radioactive waste. The technical basis for the existing system was established and optimized in initial studies using simulants in 1992. The treatment concept was validated for EPA approval in 1994 by leaching six New Waste Calcining Facility spent HEPA filters. Post-leach filter media sampling results for all six filters showed that both hazardous and radiological constituent levels were reduced so the filters could be disposed of as low-level radioactive waste. Since the validation tests the HEPA Filter Leach System has processed 78 filters in 1997 and 1998. The Idaho National Engineering and Environmental Laboratory HEPA Filter Leach System is the only mixed waste HEPA treatment system in the DOE complex. This process is of interest to many of the other DOE facilities and commercial companies that have generated mixed waste HEPA filters but currently do not have a treatment option available.

K. Archibald; K. Brewer; K. Kline; K. Pierson; K. Shackelford; M. Argyle; R. Demmer

1999-02-01

429

Anti-resonance mixing filter  

NASA Technical Reports Server (NTRS)

In a closed loop control system that governs the movement of an actuator a filter is provided that attenuates the oscillations generated by the actuator when the actuator is at a resonant frequency. The filter is preferably coded into the control system and includes the following steps. Sensing the position of the actuator with an LVDT and sensing the motor position where motor drives the actuator through a gear train. When the actuator is at a resonant frequency, a lag is applied to the LVDT signal and then combined with the motor position signal to form a combined signal in which the oscillation generated by the actuator are attenuated. The control system then controls ion this combined signal. This arrangement prevents the amplified resonance present on the LVDT signal, from causing control instability, while retaining the steady state accuracy associated with the LVDT signal. It is also a characteristic of this arrangement that the signal attenuation will always coincide with the load resonance frequency of the system so that variations in the resonance frequency will not effectuate the effectiveness of the filter.

Evans, Paul S. (Inventor)

2001-01-01

430

A fragment based step-by-step strategy for determining the most stable conformers of biomolecules  

NASA Astrophysics Data System (ADS)

For biomolecules of increased size and flexibility, more efficient and reliable strategies are always needed to determine their stable low-energy conformers. Here, we propose a fragment based step-by-step strategy to search for the full conformational space of biomolecules. In this strategy, the molecule is divided into several fragments and each of them is systematically optimized in a step-by-step fashion. It can significantly reduce the computational cost without losing any accuracy as demonstrated by the conformer search of several representative di-/tri-/tetra-peptides. Such an approach will be very useful for finding the stable conformers of large biomolecules.

Li, Hongbao; Lin, Zijing; Luo, Yi

2014-08-01

431

40 CFR 1065.590 - PM sampling media (e.g., filters) preconditioning and tare weighing.  

Code of Federal Regulations, 2012 CFR

... 2012-07-01 false PM sampling media (e.g., filters) preconditioning and...Duty Cycles § 1065.590 PM sampling media (e.g., filters) preconditioning and...the following steps to prepare PM sampling media (e.g., filters) and equipment...

2012-07-01

432

A new approach to vector median filtering based on space filling curves  

Microsoft Academic Search

The availability of a wide set of multidimensional information sources in different application fields (e.g., color