Sample records for optimized filtering step

  1. Optimal Design of Dispersion Filter for Time-Domain Split-Step Simulation of Pulse Propagation in Optical Fiber

    Microsoft Academic Search

    Yang Zhu; David V. Plant

    2012-01-01

    The nonlinear Schrödinger equation can be solved by split-step methods, where in each step, linear dispersion and nonlinear effects are treated separately. This paper considers the optimal design of an FIR filter as the time-domain implementation for the linear part. The objective is to minimize the integral of the squared error between the FIR frequency response and the desired dispersion

  2. An optimal auditory filter

    Microsoft Academic Search

    IRINO Toshio; Morinosato Wakamiya

    1995-01-01

    The optimality of the peripheral auditory filter is investigated using operator methods applied to a scale representation. A `gammachirp' function, which consists of a frequency modulated carrier and an envelope of a gamma distribution function, is found to be the optimal auditory filter in terms of minimal uncertainty if the time-scale representation is calculated in the auditory system. The gammatone

  3. Optimal separable correlation filters

    NASA Astrophysics Data System (ADS)

    McFadden, Frank E.

    2002-07-01

    Separable filters, because they are specified separately in each dimension, require less memory space and present opportunities for faster computation. Mahalanobis and Kumar1 presented a method for deriving separable correlation filters, but the filters were required to satisfy a restrictive assumption, and were thus not fully optimized. In this work, we present a general procedure for deriving separable versions of any correlation filter, using singular value decomposition (SVD), and prove that this is optimal for separable filters based on the Maximum Average Correlation Height (MACH) criterion. Further, we show that additional separable components may be used to improve the performance of the filter, with only a linear increase in computational and memory space requirements. MSTAR data is used to demonstrate the effects on sharpness of correlation peaks and locational precision, as the number of separable components is varied.

  4. Optimal Filters on the Sphere

    Microsoft Academic Search

    Jason D. Mcewen; Michael P. Hobson; Anthony N. Lasenby

    2008-01-01

    We derive optimal filters on the sphere in the context of detecting compact objects embedded in a stochastic background process. The matched filter and the scale adaptiv e filter are derived on the sphere in the most general setting, allowing for directional template profiles and filters. The p erfor- mance and relative merits of the two optimal filters are discu

  5. Robust spatiotemporal quadrature filter for multiphase stepping.

    PubMed

    Rivera, M; Marroquin, J L; Botello, S; Servín, M

    2000-01-10

    A robust algorithm for phase recovery from multi-phase-stepping images is presented. This algorithm is based on the minimization of an energy (cost) functional and is equivalent to the simultaneous application of a fixed temporal quadrature filter and a spatial adaptive quadrature filter to the phase-stepping pattern ensemble. The algorithm, believed to be new, is specially suited for those applications in which a large number of phase-stepping images may be obtained, e.g., profilometry with a computer-controlled fringe projector. We discuss the selection of parameter values and present examples of its performance in both synthetic and real image sequences. PMID:18337896

  6. Noisy Systems – Optimal Linear Filtering

    Microsoft Academic Search

    Emeritus Eric Ostertag

    \\u000a This chapter deals with noise signals, also called random or stochastic processes, which affect the plant itself or the available measurements. As mentioned earlier, the state estimator will be here a filter.\\u000a The optimal linear filter, if optimization is understood as minimization of the estimation error variance, is the well known Kalman filter. This chapter is organized as follows: after

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

    Microsoft Academic Search

    Lung-Hwa Hsieh; Kai Chang

    2003-01-01

    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

  8. OPTIMIZATION OF ADVANCED FILTER SYSTEMS

    SciTech Connect

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

    1998-04-30

    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.

  9. A nonmonotone filter trust region method for nonlinear constrained optimization

    NASA Astrophysics Data System (ADS)

    Su, Ke; Pu, Dingguo

    2009-01-01

    In this paper, we present a nonmonotone filter trust region algorithm for solving nonlinear equality constrained optimization. Similar to Bryd-Omojokun class of algorithms, each step is composed of a quasi-normal step and a tangential step. This new method has more flexibility for the acceptance of the trial step compared to the filter methods, and requires less computational costs compared with the monotone methods. Under reasonable conditions, we give the globally convergence properties. Numerical tests are presented that confirm the efficiency of the approach.

  10. Direct electromagnetic optimization of microwave filters

    Microsoft Academic Search

    S. Bila; D. Baillargeat; M. Aubourg; S. Verdeyme; P. Guillon; F. Seyfert; J. Grimm; L. Baratchart; C. Zanchi; J. Sombrin

    2001-01-01

    This article explores an optimization procedure for microwave filters and multiplexers. The procedure is initialized by a classical filter synthesis based on a segmented electromagnetic synthesis that provides the basic dimensions of the structure. The optimization loop, which combines a global electromagnetic analysis and a coupling identification, improves the structure response compared to an empirical optimization

  11. Optimal and robust noncausal filter formulations

    Microsoft Academic Search

    Garry A. Einicke

    2006-01-01

    The paper describes an optimal minimum-variance noncausal filter or fixed-interval smoother. The optimal solution involves a cascade of a Kalman predictor and an adjoint Kalman predictor. A robust smoother involving H? predictors is also described. Filter asymptotes are developed for output estimation and input estimation problems which yield bounds on the spectrum of the estimation error. These bounds lead to

  12. OPTIMIZATION OF ADVANCED FILTER SYSTEMS

    SciTech Connect

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

    2002-06-30

    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.

  13. Estimation of optimal Kalman filter gain from non-optimal filter residuals

    NASA Technical Reports Server (NTRS)

    Chen, Chung-Wen; Huang, Jen-Kuang

    1991-01-01

    This paper presents a novel method of estimating the optimal steady state Kalman filter gain of a linear discrete time-invariant system from a non-optimal Kalman filter residual sequence. The relation between the optimal residual sequence and a signal derived from the non-optimal residual sequence is described by a Moving Average (MA) model whose coefficients are expressed in terms of the state space parameters and the optimal steady state Kalman filter gain. In order to identify the MA model, a whitening filter of the derived signal, which corresponds to an AutoRegressive (AR) model of the signal, is first identified using the least-squares method. Then the inverse filter of the whitening filter, which corresponds to the MA model, is calculated. From the coefficients of the identified MA model, the optimal steady state Kalman filter gain can be obtained. Numerical example is provided to illustrate the feasibility of this approach.

  14. Particle Filter with Swarm Move for Optimization

    E-print Network

    Yang, Shengxiang

    method in particle swarm optimization (PSO). In this way, the PSO update equation is treated the ability of PSO in searching the optimal position can be embedded into the particle filter optimization in both convergence speed and final fitness in comparison with the PSO algorithm over a set of standard

  15. Optimization of the Split-step Fourier Method in Modeling Optical Fiber Communications Systems

    E-print Network

    Maryland, Baltimore County, University of

    Optimization of the Split-step Fourier Method in Modeling Optical Fiber Communications Systems Oleg of different implementations of the split-step Fourier method for solving the nonlinear Schrödinger equation-order dispersion, the Raman 2 #12;effect, and filtering [2]. In this paper we focus on the split-step Fourier

  16. A FILTER METHOD WITH UNIFIED STEP COMPUTATION FOR ...

    E-print Network

    2013-05-09

    This contrasts traditional filter methods that use a (separate) restoration phase designed to ... move the initial guess into the strict interior of the feasible region. It is from this interior location ..... By design, the trial step sk is a descent direction for.

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

    PubMed Central

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

    2014-01-01

    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

  18. Steps Toward Optimal Competitive Scheduling

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

    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

  19. Optimal Multiobjective Design of Digital Filters Using Taguchi Optimization Technique

    NASA Astrophysics Data System (ADS)

    Ouadi, Abderrahmane; Bentarzi, Hamid; Recioui, Abdelmadjid

    2014-01-01

    The multiobjective design of digital filters using the powerful Taguchi optimization technique is considered in this paper. This relatively new optimization tool has been recently introduced to the field of engineering and is based on orthogonal arrays. It is characterized by its robustness, immunity to local optima trapping, relative fast convergence and ease of implementation. The objectives of filter design include matching some desired frequency response while having minimum linear phase; hence, reducing the time response. The results demonstrate that the proposed problem solving approach blended with the use of the Taguchi optimization technique produced filters that fulfill the desired characteristics and are of practical use.

  20. Optimal multiobjective design of digital filters using spiral optimization technique.

    PubMed

    Ouadi, Abderrahmane; Bentarzi, Hamid; Recioui, Abdelmadjid

    2013-01-01

    The multiobjective design of digital filters using spiral optimization technique is considered in this paper. This new optimization tool is a metaheuristic technique inspired by the dynamics of spirals. It is characterized by its robustness, immunity to local optima trapping, relative fast convergence and ease of implementation. The objectives of filter design include matching some desired frequency response while having minimum linear phase; hence, reducing the time response. The results demonstrate that the proposed problem solving approach blended with the use of the spiral optimization technique produced filters which fulfill the desired characteristics and are of practical use. PMID:24083108

  1. Optimization of Cosine Modulated Filter Bank for Narrowband RFI

    E-print Network

    Rajan, Dinesh

    Optimization of Cosine Modulated Filter Bank for Narrowband RFI Yingsi Liang Department frequency interfer- ence (RFI). The conventionally used optimization criterion for bandpass filtering ripple. The proposed optimization scheme is designed particularly to combat RFI with completely known

  2. Optimal time step for incompressible SPH

    NASA Astrophysics Data System (ADS)

    Violeau, Damien; Leroy, Agnès

    2015-05-01

    A classical incompressible algorithm for Smoothed Particle Hydrodynamics (ISPH) is analyzed in terms of critical time step for numerical stability. For this purpose, a theoretical linear stability analysis is conducted for unbounded homogeneous flows, leading to an analytical formula for the maximum CFL (Courant-Friedrichs-Lewy) number as a function of the Fourier number. This gives the maximum time step as a function of the fluid viscosity, the flow velocity scale and the SPH discretization size (kernel standard deviation). Importantly, the maximum CFL number at large Reynolds number appears twice smaller than with the traditional Weakly Compressible (WCSPH) approach. As a consequence, the optimal time step for ISPH is only five times larger than with WCSPH. The theory agrees very well with numerical data for two usual kernels in a 2-D periodic flow. On the other hand, numerical experiments in a plane Poiseuille flow show that the theory overestimates the maximum allowed time step for small Reynolds numbers.

  3. Optimal subband filters to maximize coding gain

    NASA Astrophysics Data System (ADS)

    Tanimoto, Masayuki; Yamada, Akio; Wakatsuki, Norio

    1993-10-01

    The optimal analysis/synthesis filters giving the maximum coding gain are derived in subband schemes. The optimal analysis filters consist of the emphasis of the picture signal and ideal band-splitting. The characteristics of the emphasis is determined by the spectrum of the picture signal. A large improvement of coding gain is achieved by the subband scheme with the optimal subband filters obtained here. Approximated emphasis characteristic determined from a spectrum model of picture signals can be used and the ideal band-splitting filters can be replaced by conventional subband filters since the degradation of coding gain due to these approximations is small. Computer simulation of super HD image coding by the proposed scheme is performed. SN ratio of the reconstructed image is increased and edges are reconstructed very well compared to the conventional subband scheme. The proposed scheme is very suited to super HD image coding since the improvement of SN ratio is large for images with high correlation between the neighboring pixels.

  4. MEDOF - MINIMUM EUCLIDEAN DISTANCE OPTIMAL FILTER

    NASA Technical Reports Server (NTRS)

    Barton, R. S.

    1994-01-01

    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.

  5. Optimal design of active EMC filters

    NASA Astrophysics Data System (ADS)

    Chand, B.; Kut, T.; Dickmann, S.

    2013-07-01

    A recent trend in automotive industry is adding electrical drive systems to conventional drives. The electrification allows an expansion of energy sources and provides great opportunities for environmental friendly mobility. The electrical powertrain and its components can also cause disturbances which couple into nearby electronic control units and communication cables. Therefore the communication can be degraded or even permanently disrupted. To minimize these interferences, different approaches are possible. One possibility is to use EMC filters. However, the diversity of filters is very large and the determination of an appropriate filter for each application is time-consuming. Therefore, the filter design is determined by using a simulation tool including an effective optimization algorithm. This method leads to improvements in terms of weight, volume and cost.

  6. Customized optimal filter for eliminating operator's tremor

    NASA Astrophysics Data System (ADS)

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

    1995-12-01

    Remote manually operated tasks such as those found in teleoperation, virtual reality, or joystick-based computer access, require the generation of an intermediate signal which is transmitted to the controlled subsystem (robot arm, virtual environment or cursor). When man-machine movements are distorted by tremor, performance can be improved by digitally filtering the intermediate signal before it reaches the controlled device. This paper introduces a novel filtering framework in which digital equalizers are optimally designed after 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 highly ill-conditioned autocorrelation matrices, which often result in useless or unstable solutions. A new performance indicator is introduced, namely the F-MSEd, and the optimal equalizer according to this new criterion is developed. Ill-condition of the autocorrelation matrix is overcome using a novel method which we call pulled-optimization. Experiments performed with both a person with tremor disability, and a vibration inducing device, show significant results.

  7. Program Computes SLM Inputs To Implement Optimal Filters

    NASA Technical Reports Server (NTRS)

    Barton, R. Shane; Juday, Richard D.; Alvarez, Jennifer L.

    1995-01-01

    Minimum Euclidean Distance Optimal Filter (MEDOF) program generates filters for use in optical correlators. Analytically optimizes filters on arbitrary spatial light modulators (SLMs) of such types as coupled, binary, fully complex, and fractional-2pi-phase. Written in C language.

  8. Envelope-constrained H? filter design: An LMI optimization approach

    Microsoft Academic Search

    Zhiqiang Tan; Yeng Chai Soh; Lihua Xie

    2000-01-01

    In this correspondence, we solve the envelope-constrained H? filter design problem by minimizing the H? norm of the filtering error transfer function subject to the constraint that the filter output is contained in a prescribed envelope. The filter design is transformed into a standard linear matrix inequality (LMI) optimization problem

  9. Nonuniform principal component filter banks: definitions, existence, and optimality

    Microsoft Academic Search

    Sony J. Akkarakaran; Palghat P. Vaidyanathan

    2000-01-01

    The optimality of principal component filter banks (PCFBs) for data compression has been observed in many works to varying extents. Recent work by the authors has made explicit the precise connection between the optimality of uniform orthonormal filter banks (FBs) and the principal component property: The PCFB is optimal whenever the minimization objective is a concave function of the subband

  10. SubOptimal Kalman Filter for Multimodeling Systems

    Microsoft Academic Search

    Hiroaki Mukaidani; Yasuhiro Kawata; Yoshiyuki Tanaka; Hua Xu

    2003-01-01

    In this paper, we study the optimal Kalman filtering problem for multiparameter singularly perturbed sys- tem (MSPS). The attention is focused on the design of the high-order approximate Kalman filters. It is shown that the resulting filters in fact remove ill-conditioning of the original full-order singularly perturbed Kalman filters. In addition the resulting filters can be used compared with the

  11. The Design of Optimal Convolutional Filters via Linear Programming

    Microsoft Academic Search

    RALPH K. CAVIN; C. H. Ray; V. THOMAS RHYNE

    1969-01-01

    Computational algorithms are given for the design of optimal, finite-length, convolutional filters with finite-length input sequences. Design techniques are developed for minimum-weighted-mean-square-error filters (MWMSE), for minimum-weighted-absolute-error filters (MWAE), and for filters which minimize the maximum output error (minimax). It is shown that the coefficients of the MWAE and minimax filters can be obtained by using standard linear programming methods. Next,

  12. A design technique for stepped circular waveguide dual-mode filters for broadband contiguous multiplexers

    Microsoft Academic Search

    Hai Hu; Ke-Li Wu; Richard J. Cameron

    2011-01-01

    A stepped circular waveguide cavity provides an effective way for shifting or even suppressing unwanted spurious modes in a circular waveguide dual-mode (CWDM) filter. This useful property may be used in a wideband waveguide contiguous channel output multiplexer (OMUX) in satellite payloads. In this paper, a technique for automatically designing a stepped circular waveguide dual-mode (SCWDM) filter is presented. A

  13. A family of variable step-size affine projection adaptive filter algorithms using statistics of channel impulse response

    NASA Astrophysics Data System (ADS)

    Shams Esfand Abadi, Mohammad; AbbasZadeh Arani, Seyed Ali Asghar

    2011-12-01

    This paper extends the recently introduced variable step-size (VSS) approach to the family of adaptive filter algorithms. This method uses prior knowledge of the channel impulse response statistic. Accordingly, optimal step-size vector is obtained by minimizing the mean-square deviation (MSD). The presented algorithms are the VSS affine projection algorithm (VSS-APA), the VSS selective partial update NLMS (VSS-SPU-NLMS), the VSS-SPU-APA, and the VSS selective regressor APA (VSS-SR-APA). In VSS-SPU adaptive algorithms the filter coefficients are partially updated which reduce the computational complexity. In VSS-SR-APA, the optimal selection of input regressors is performed during the adaptation. The presented algorithms have good convergence speed, low steady state mean square error (MSE), and low computational complexity features. We demonstrate the good performance of the proposed algorithms through several simulations in system identification scenario.

  14. Synthesizing Optimal Filters for Crosstalkcancellation for HighSpeed Buses

    E-print Network

    Greenstreet, Mark

    Synthesizing Optimal Filters for Crosstalk­cancellation for High­Speed Buses Jihong Ren and Mark in crosstalk cancellation for high­bandwidth, digital commu­ nication. In practice, filter design the structure of a typical channel with a pre­equalization filter for crosstalk cancellation

  15. Optimally stabilized PET image denoising using trilateral filtering.

    PubMed

    Mansoor, Awais; Bagci, Ulas; Mollura, Daniel J

    2014-01-01

    Low-resolution and signal-dependent noise distribution in positron emission tomography (PET) images makes denoising process an inevitable step prior to qualitative and quantitative image analysis tasks. Conventional PET denoising methods either over-smooth small-sized structures due to resolution limitation or make incorrect assumptions about the noise characteristics. Therefore, clinically important quantitative information may be corrupted. To address these challenges, we introduced a novel approach to remove signal-dependent noise in the PET images where the noise distribution was considered as Poisson-Gaussian mixed. Meanwhile, the generalized Anscombe's transformation (GAT) was used to stabilize varying nature of the PET noise. Other than noise stabilization, it is also desirable for the noise removal filter to preserve the boundaries of the structures while smoothing the noisy regions. Indeed, it is important to avoid significant loss of quantitative information such as standard uptake value (SUV)-based metrics as well as metabolic lesion volume. To satisfy all these properties, we extended bilateral filtering method into trilateral filtering through multiscaling and optimal Gaussianization process. The proposed method was tested on more than 50 PET-CT images from various patients having different cancers and achieved the superior performance compared to the widely used denoising techniques in the literature. PMID:25333110

  16. Optimal filters for detecting cosmic bubble collisions

    NASA Astrophysics Data System (ADS)

    McEwen, J. D.; Feeney, S. M.; Johnson, M. C.; Peiris, H. V.

    2012-05-01

    A number of well-motivated extensions of the ?CDM concordance cosmological model postulate the existence of a population of sources embedded in the cosmic microwave background. One such example is the signature of cosmic bubble collisions which arise in models of eternal inflation. The most unambiguous way to test these scenarios is to evaluate the full posterior probability distribution of the global parameters defining the theory; however, a direct evaluation is computationally impractical on large datasets, such as those obtained by the Wilkinson Microwave Anisotropy Probe (WMAP) and Planck. A method to approximate the full posterior has been developed recently, which requires as an input a set of candidate sources which are most likely to give the largest contribution to the likelihood. In this article, we present an improved algorithm for detecting candidate sources using optimal filters, and apply it to detect candidate bubble collision signatures in WMAP 7-year observations. We show both theoretically and through simulations that this algorithm provides an enhancement in sensitivity over previous methods by a factor of approximately two. Moreover, no other filter-based approach can provide a superior enhancement of these signatures. Applying our algorithm to WMAP 7-year observations, we detect eight new candidate bubble collision signatures for follow-up analysis.

  17. Nonmonotone Filter Method for Nonlinear Optimization

    E-print Network

    2009-10-14

    Oct 14, 2009 ... The sequential quadratic programming (SQP) method is an iterative method for ... Gould and Toint (2003) introduced a nonmonotone trust-region filter al- ...... g- and l-filter with M = 2, though we have also experimented with.

  18. CLASSIFICATION SCHEMES FOR STEP SOUNDS BASED ON GAMMATONE-FILTERS

    Microsoft Academic Search

    Robert Annies; Hendrik Purwins; Klaus Obermayer

    In this study the classification performance of 2 machine learning methods and 2 sound representations schemes are compared, having the focus on short impact like sounds: Footsteps have been classified according to the material of the floor and the shoe type. The gamma-tone auditory filter- bank is a spectral analyser, that converts a given signal into a multi-channel simulation of

  19. Design of passive filter circuit based on robust optimization

    NASA Astrophysics Data System (ADS)

    Zhao, Hong; Chen, Gang

    2013-03-01

    In view on this change of filter performance by the deviation of circuit component parameter values from its design values, the concept of robust optimization design for the passive filter circuit is presented. The function, that is to minimize the ripples and maximal variations of system performance is chosen as the objective function. The optimization strategy by combining random direction searching method with compound optimum was adopted for solving this nonlinear programming problem with two-level optimization. This theory is used on an 800MHz transmitter bandpass filter circuit. By comparing with original design and conventional optimization, passband performance of the robust optimized circuit is more flat and its fluctuation is more small when component parameters change within their rated tolerance. So filter performance of the circuit is improved, and the method mentioned in this paper is effective and superior.

  20. Optimization design of biorthogonal filter banks for image compression

    Microsoft Academic Search

    Yi Shang; Longzhuang Li; Benjamin W. Wah

    2001-01-01

    In this paper, we present a new approach for designing filter banks for image compression. This approach has two major components: optimization and generalization. In the optimization phase, we formulate the design problem as a nonlinear optimization problem whose objective consists of both the performance metrics of the image coder, such as the peak signal-to-noise ratio (PSNR), and those of

  1. OPTIMIZATION OF AUTOMOTIVE VALVE TRAIN COMPONENTS WITH IMPLICT FILTERING \\Lambda

    E-print Network

    in this application. In x 3 we present the details of the valve train model and the optimization problems to be solvedOPTIMIZATION OF AUTOMOTIVE VALVE TRAIN COMPONENTS WITH IMPLICT FILTERING \\Lambda T. D. CHOI y , O identification and optimization in automotive valve train design. We extend our previous work by using a more

  2. FILTER-BANK OPTIMIZATION WITH CONVEX OBJECTIVES, AND THE OPTIMALITY OF PRINCIPAL COMPONENT FORMS1

    Microsoft Academic Search

    Sony Akkarakaran; P. P. Vaidyanathan

    This paper proposes a general framework for the optimization of orthonormal filter banks (FB's) for given input statistics. This includes as special cases, many recent results on filter bank optimization for compression. It also solves problems that have not been considered thus far. FB optimization for coding gain maximization (for compression applications) has been well studied before. The optimum FB

  3. Pump and filtering optimization in Mamyshev regenerator

    NASA Astrophysics Data System (ADS)

    Supe, Andis; Fernandes, Gil M.; Muga, Nelson J.; Pinto, Armando N.; Ferreira, Mario F. S.

    2013-11-01

    In this paper we present results from the study of optical signal regeneration using Mamyshev type regenerator. We have performed the simulations and experimental characterization of regenerator by obtaining it`s transfer function and output optical signal to noise ratio measurements for two different filters - fixed and a tunable optical filter. Investigated regenerator setup consists of a high power erbium doped fiber amplifier, highly nonlinear fiber and a single stage optical filtering. Signal used for regeneration was an on-off keying return to zero code 40 Gbps pulse sequence. To find out optimum filter pass-band shift from signal`s central wavelength the regenerator`s transfer function was measured. Results show that highest output signal to noise ratio improvement for the fixed filter is at 0.6nm shift and amplifier output power set to 63 mW. While the tunable filter shift is 0.7nm at the 100 mW power level.

  4. A SIMULATION-BASED OPTIMIZATION APPROACH TO POLYMER EXTRUSION FILTER

    E-print Network

    Jenkins, Lea

    is the effective removal of debris, via filtration, from the polymer melt during the extrusion process. We propose model that describes the deposition of debris particles in the filter. Optimization algorithms are used. ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¢¡¢¡¢¡¢¡¢¢¡¢¡¢¡¢¡¢ £¤£¤£¤£¤£¤£¤£¤££¤£¤£¤£¤£¤£¤£¤££¤£¤£¤£¤£¤£¤£¤£ ¥¤¥¤¥¤¥¤¥¤¥¤¥¥¤¥¤¥¤¥¤¥¤¥¤¥¥¤¥¤¥¤¥¤¥¤¥¤¥ .. . Godets Convergence Guide Air Quench Filter Metering Pump Spinneret Spin Bobbin Polymer Melt Figure 1

  5. Estimating Optimal Tracking Filter Performance for Manned Maneuvering Targets

    Microsoft Academic Search

    Robert Singer

    1970-01-01

    The majority of tactical weapons systems require that manned maneuverable vehicles, such as aircraft, ships, and submarines, be tracked accurately. An optimal Kalman filter has been derived for this purpose using a target model that is simple to implement and that represents closely the motions of maneuvering targets. Using this filter, parametric tracking accuracy data have been generated as a

  6. Robustness of optimal binary filters: analysis and design 

    E-print Network

    Grigoryan, Artyom M

    1999-01-01

    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...

  7. Optimization of Synthesis Oversampled Complex Filter Banks

    E-print Network

    Paris-Sud XI, Université de

    property on the synthesis side, which is serviceable to processing real-valued signals. As an invertible localization, frequency localiza- tion, lapped transforms, modulated filter banks. I. INTRODUCTION Since the 70s, filter banks (FBs) have become a central tool in signal/image processing and commu- nications

  8. Ares-I Bending Filter Design using a Constrained Optimization Approach

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

    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.

  9. Wide-stopband microstrip bandpass filters using dissimilar quarter-wavelength stepped-impedance resonators

    Microsoft Academic Search

    Shih-Cheng Lin; Pu-Hua Deng; Yo-Shen Lin; Chi-Hsueh Wang; Chun Hsiung Chen

    2006-01-01

    Wide-stopband and compact microstrip bandpass filters (BPFs) are proposed using various dissimilar quarter-wavelength (?\\/4) stepped-impedance resonators (SIRs) for multiple spurious suppression. The use of ?\\/4 SIRs is essential in widening the filter stopband and reducing the circuit size. By properly arranging the individual ?\\/4 SIR, which has the same fundamental resonance frequency f0, but has different spurious (harmonic) resonance frequencies,

  10. PID controller tuning using particle filtering optimization

    Microsoft Academic Search

    Jie Li; Tianyou Chai; Lisheng Fan; Li Pan; Jingkuan Gong

    2010-01-01

    The PID controller is one of the most popular controllers, due to its remarkable effectiveness, simplicity of implementation and broad applicability. However, the conventional approach for parameter optimization in PID controller is easy to produce surge and big overshoot, and therefore heuristics optimization methods such as genetic algorithm (GA), particle swarm optimization (PSO) are employed to enhance the capability of

  11. Principal component filter banks for optimal multiresolution analysis

    Microsoft Academic Search

    Michail K. Tsatsanis; Georgios B. Giannakis

    1995-01-01

    An important issue in multiresolution analysis is that of optimal basis selection. An optimal P-band perfect reconstruction filter bank (PRFB) is derived in this paper, which minimizes the approximation error (in the mean-square sense) between the original signal and its low-resolution version. The resulting PRFB decomposes the input signal into uncorrelated, low-resolution principal components with decreasing variance. Optimality issues are

  12. Sub-Optimal Ensemble Filters and distributed hydrologic modeling: a new challenge in flood forecasting

    NASA Astrophysics Data System (ADS)

    Baroncini, F.; Castelli, F.

    2009-09-01

    Data assimilation techniques based on Ensemble Filtering are widely regarded as the best approach in solving forecast and calibration problems in geophysics models. Often the implementation of statistical optimal techniques, like the Ensemble Kalman Filter, is unfeasible because of the large amount of replicas used in each time step of the model for updating the error covariance matrix. Therefore the sub optimal approach seems to be a more suitable choice. Various sub-optimal techniques were tested in atmospheric and oceanographic models, some of them are based on the detection of a "null space". Distributed Hydrologic Models differ from the other geo-fluid-dynamics models in some fundamental aspects that make complex to understanding the relative efficiency of the different suboptimal techniques. Those aspects include threshold processes , preferential trajectories for convection and diffusion, low observability of the main state variables and high parametric uncertainty. This research study is focused on such topics and explore them through some numerical experiments on an continuous hydrologic model, MOBIDIC. This model include both water mass balance and surface energy balance, so it's able to assimilate a wide variety of datasets like traditional hydrometric "on ground" measurements or land surface temperature retrieval from satellite. The experiments that we present concern to a basin of 700 kmq in center Italy, with hourly dataset on a 8 months period that includes both drought and flood events, in this first set of experiment we worked on a low spatial resolution version of the hydrologic model (3.2 km). A new Kalman Filter based algorithm is presented : this filter try to address the main challenges of hydrological modeling uncertainty. The proposed filter use in Forecast step a COFFEE (Complementary Orthogonal Filter For Efficient Ensembles) approach with a propagation of both deterministic and stochastic ensembles to improve robustness and convergence proprieties. After, through a P.O.D. Reduction from control theory, we compute a Reduced Order Forecast Covariance matrix . In analysis step the filter uses a LE (Local Ensemble) Kalman Filter approach. We modify the LE Kalman Filter assimilation scheme and we adapt its formulation to the P.O.D. Reduced sub-space propagated in forecast step. Through this, assimilation of observations is made only in the maximum covariance directions of the model error. Then the efficiency of this technique is weighed in term of hydrometric forecast accuracy in a preliminary convergence test of a synthetic rainfall event toward a real rain fall event.

  13. Design of optimal correlation filters for hybrid vision systems

    NASA Technical Reports Server (NTRS)

    Rajan, Periasamy K.

    1990-01-01

    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.

  14. Design of optimal correlation filters for hybrid vision systems

    NASA Astrophysics Data System (ADS)

    Rajan, Periasamy K.

    1990-12-01

    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.

  15. Design and performance optimization of fiber optic adaptive filters.

    PubMed

    Paparao, P; Ghosh, A; Allen, S D

    1991-05-10

    There is a great need for easy-to-fabricate and versatile fiber optic signal processing systems in which optical fibers are used for the delay and storage of wideband guided lightwave signals. We describe the design of the least-mean-square algorithm-based fiber optic adaptive filters for processing guided lightwave signals in real time. Fiber optic adaptive filters can learn to change their parameters or to process a set of characteristics of the input signal. In our realization we employ as few electronic devices as possible and use optical computation to utilize the advantages of optics in the processing speed, parallelism, and interconnection. Many schemes for optical adaptive filtering of electronic signals are available in the literature. The new optical adaptive filters described in this paper are for optical processing of guided lightwave signals, not electronic signals. We analyzed the convergence or learning characteristics of the adaptive filtering process as a function of the filter parameters and the fiber optic hardware errors. From this analysis we found that the effects of the optical round-off errors and noise can be reduced, and the learning speed can be comparatively increased in our design through an optimal selection of the filter parameters. A general knowledge of the fiber optic hardware, the statistics of the lightwave signal, and the desired goal of the adaptive processing are enough for this optimum selection of the parameters. Detailed computer simulations validate the theoretical results of performance optimization. PMID:20700365

  16. Millimeter-wave GaAs stepped-impedance hairpin resonator filters using surface micromachining

    NASA Astrophysics Data System (ADS)

    Cho, Ju-Hyun; Yun, Tae-Soon; Baek, Tae-Jong; Ko, Back-Seok; Shin, Dong-Hoon; Lee, Jong-Chul

    2005-05-01

    In this paper, microstrip stepped-impedance hairpin resonator (SIR) low-pass filter (LPF) and slow-wave band-pass filter (BPF) using dielectric supported air-gapped microstrip line (DAML) of surface micromachining on GaAs substrate are proposed. The DAML structure, which is a new low-loss micromachining transmission line, is useful for the integration of MEMS and/or MMIC components. Design parameters for the proposed SIR low-pass and slow-wave band-pass filters are derived based on stepped-impedance theory. The proposed slow-wave BPF is designed to produce a passband of 10% at the fundamental frequency of 60 GHz. and a new SIR LPF with aperture and IDC (inter-digital capacitor) is designed for 3-dB cutoff frequency of 33 GHz. The measurement results of the BPF filter and LPF filter agree well with simulation results. These filters are useful for many millimeter-wave system applications.

  17. Robust adapative Kalman filtering for systems with unknown step inputs and non-Gaussian measurement errors

    Microsoft Academic Search

    R. LYNN KIRLIN; ALIREZA MOGHADDAMJOO

    1986-01-01

    Target tracking with Kalman filters is hampered by target maneuvering and unknown process and measurement noises. We show that moving data windows may be used to analyze state and measurement error sequences, determining robust estimates of bias and covariance. For steps in the system forcing functions and non-Gaussian measurement errors, the robust estimators yield improvements over linear bias and covariance

  18. Optimal Filtering in the Salamander Retina

    Microsoft Academic Search

    Fred Rieke; W. Geoffrey Owen; William Bialek

    The dark-adapted visual system can count photons with a reliability lim- ited by thermal noise in the rod photoreceptors - the processing circuitry between the rod cells and the brain is essentially noiseless and in fact may be close to optimal. Here we design an optimal signal processor which estimates the time-varying light intensity at the retina based on the

  19. Optimal Signal Processing of Frequency-Stepped CW Radar Data

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    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.

  20. Optimal Signal Processing of Frequency-Stepped CW Radar Data

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    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.

  1. A unified optimization framework for equalization filter synthesis

    Microsoft Academic Search

    Jihong Ren; Mark R. Greenstreet

    2005-01-01

    We present a novel method for jointly optimizing FIR filters for pre-equalization, decision feedback equalization, and near-end crosstalk cancellation. The unified optimization problem is a linear program, and we describe sparse matrix techniques for its efficient solution. We illustrate our approach with uni- and bi-directional buses using differential signaling in both intra-board and cross-backplane scenarios.

  2. A neural network-based optimal spatial filter design method for motor imagery classification.

    PubMed

    Yuksel, Ayhan; Olmez, Tamer

    2015-01-01

    In this study, a novel spatial filter design method is introduced. Spatial filtering is an important processing step for feature extraction in motor imagery-based brain-computer interfaces. This paper introduces a new motor imagery signal classification method combined with spatial filter optimization. We simultaneously train the spatial filter and the classifier using a neural network approach. The proposed spatial filter network (SFN) is composed of two layers: a spatial filtering layer and a classifier layer. These two layers are linked to each other with non-linear mapping functions. The proposed method addresses two shortcomings of the common spatial patterns (CSP) algorithm. First, CSP aims to maximize the between-classes variance while ignoring the minimization of within-classes variances. Consequently, the features obtained using the CSP method may have large within-classes variances. Second, the maximizing optimization function of CSP increases the classification accuracy indirectly because an independent classifier is used after the CSP method. With SFN, we aimed to maximize the between-classes variance while minimizing within-classes variances and simultaneously optimizing the spatial filter and the classifier. To classify motor imagery EEG signals, we modified the well-known feed-forward structure and derived forward and backward equations that correspond to the proposed structure. We tested our algorithm on simple toy data. Then, we compared the SFN with conventional CSP and its multi-class version, called one-versus-rest CSP, on two data sets from BCI competition III. The evaluation results demonstrate that SFN is a good alternative for classifying motor imagery EEG signals with increased classification accuracy. PMID:25933101

  3. Optimal filtering in multipulse sequences for nuclear quadrupole resonance detection

    NASA Astrophysics Data System (ADS)

    Osokin, D. Ya.; Khusnutdinov, R. R.; Mozzhukhin, G. V.; Rameev, B. Z.

    2014-05-01

    The application of the multipulse sequences in nuclear quadrupole resonance (NQR) detection of explosive and narcotic substances has been studied. Various approaches to increase the signal to noise ratio (SNR) of signal detection are considered. We discussed two modifications of the phase-alternated multiple-pulse sequence (PAMS): the 180° pulse sequence with a preparatory pulse and the 90° pulse sequence. The advantages of optimal filtering to detect NQR in the case of the coherent steady-state precession have been analyzed. It has been shown that this technique is effective in filtering high-frequency and low-frequency noise and increasing the reliability of NQR detection. Our analysis also shows the PAMS with 180° pulses is more effective than PSL sequence from point of view of the application of optimal filtering procedure to the steady-state NQR signal.

  4. Na-Faraday rotation filtering: The optimal point

    PubMed Central

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

    2014-01-01

    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

  5. Na-Faraday rotation filtering: the optimal point.

    PubMed

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

    2014-01-01

    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

  6. Optimal design of Biquad Switched-Capacitor Active Filters 

    E-print Network

    Jo, Han Cheol

    1986-01-01

    objectives. 33 Set of realizable objects Optimal g tradeofi' curve Figure 4-2 Realizable multiple objectives and optimal trade-off curve. F=minimized C~, & with fixed S& and f /fp DMG k (finite) Figure 4-3 Construction of optimal tradeoff-curve (C... in Biquadratic SC filters is presented. There are two cost functions considered, one is a single objective function, the other is a multiple objective function. A weighting function is used in the last case to emphasize the importance of the variables...

  7. Optimal color image restoration: Wiener filter and quaternion Fourier transform

    NASA Astrophysics Data System (ADS)

    Grigoryan, Artyom M.; Agaian, Sos S.

    2015-03-01

    In this paper, we consider the model of quaternion signal degradation when the signal is convoluted and an additive noise is added. The classical model of such a model leads to the solution of the optimal Wiener filter, where the optimality with respect to the mean square error. The characteristic of this filter can be found in the frequency domain by using the Fourier transform. For quaternion signals, the inverse problem is complicated by the fact that the quaternion arithmetic is not commutative. The quaternion Fourier transform does not map the convolution to the operation of multiplication. In this paper, we analyze the linear model of the signal and image degradation with an additive independent noise and the optimal filtration of the signal and images in the frequency domain and in the quaternion space.

  8. The use of variable-step delta modulation in digital filtering and correlation analysis

    NASA Astrophysics Data System (ADS)

    Pogribnoi, V. A.

    1985-11-01

    General expressions are obtained for convolutions and correlation functions using variable-quantization-step DM in conjunction with PCM, making it possible to realize low-cost processor circuits. Algorithms for the operation of processors for digital filtering and correlation analysis on the basis of this type of modulation are proposed. In addition, they are compared with algorithms for the operation of processors with linear PCM, DM, and delta-sigma modulation.

  9. A bench scale study of a one-step dissolution process for treating contaminated fiberglass filters

    SciTech Connect

    Policke, T.A.; Ritter, J.A.

    1995-12-01

    High efficiency mist eliminators (HEME) and high efficiency particulate air filters (HEPA) made of High fiberglass will be used at the Savannah River Site (SRS) to remove particulate matter from offgases generated during melter feed preparation and vitrification of high-level radioactive waste (HLW) at the Defense Waste Processing Facility (DWPF). These filters will be contaminated with high-level, radioactive species and also with various high-boiling organic compounds. For this reason, a process was developed at the Savannah River Technology Center (SRTC) that will dissolve the spent filters so that the residues may be recycled to the HLW tanks for eventual vitrification. This process involves boiling the filters sequentially in NaOH, HN0{sub 3} and NaOH, while contained in a stainless steal wire mesh frame assembly. The objective of this communication is to present some of the original preliminary work done by Ritter on the simple one-step dissolution process. The results from six bench-scale experiments are reported for the dissolution of an organically-fouled sample of HEME obtained from the Integrated DWPF Melter (IDMS) offgas filtration system. The preliminary effects of filter packing density, air sparging versus rotating basket agitation, fouling, and adding Triton X-405 as a dispersing agent are reported.

  10. Design of Two-Dimensional Infinite Impulse Response Recursive Filters Using Hybrid Multiagent Particle Swarm Optimization

    Microsoft Academic Search

    Rajesh Kumar; Anupam Kumar

    2010-01-01

    We incorporate the optimization problem of two-dimensional infinite impulse response (IIR) recursive filters and the optimization methodology of hybrid multiagent particle swarm optimization (HMAPSO) and then apply the resultant optimized IIR filter in image processing for justifying HMAPSO robustness over other algorithm and its role in optimizing real-time situations. The design of the 2-D IIR filter is reduced to a

  11. Near-optimal Kalman filters for multiparameter singularly perturbed linear systems

    Microsoft Academic Search

    Hiroaki Mukaidani

    2003-01-01

    In this brief, we study the near-optimal Kalman filtering problem for multiparameter singularly perturbed system (MSPS). The attention is focused on the design of the near-optimal Kalman filters. It is shown that the resulting filters in fact remove ill-conditioning of the original full-order singularly perturbed Kalman filters. In addition the resulting filters can be used compared with the previously proposed

  12. A biologically inspired improvement strategy for particle filter: Ant colony optimization assisted particle filter

    Microsoft Academic Search

    Junpei Zhong; Yu-fai Fung; Mingjun Dai

    2010-01-01

    Particle Filter (PF) is a sophisticated model estimation technique based on simulation. Due to the natural limitations of\\u000a PF, two problems, namely particle impoverishment and sample size dependency, frequently occur during the particles updating\\u000a stage and these problems will limit the accuracy of the estimation results. In order to alleviate these problems, Ant Colony\\u000a Optimization is incorporated into the generic

  13. A Peptide Filtering Relation Quantifies MHC Class I Peptide Optimization

    PubMed Central

    Goldstein, Leonard D.; Howarth, Mark; Cardelli, Luca; Emmott, Stephen; Elliott, Tim; Werner, Joern M.

    2011-01-01

    Major Histocompatibility Complex (MHC) class I molecules enable cytotoxic T lymphocytes to destroy virus-infected or cancerous cells, thereby preventing disease progression. MHC class I molecules provide a snapshot of the contents of a cell by binding to protein fragments arising from intracellular protein turnover and presenting these fragments at the cell surface. Competing fragments (peptides) are selected for cell-surface presentation on the basis of their ability to form a stable complex with MHC class I, by a process known as peptide optimization. A better understanding of the optimization process is important for our understanding of immunodominance, the predominance of some T lymphocyte specificities over others, which can determine the efficacy of an immune response, the danger of immune evasion, and the success of vaccination strategies. In this paper we present a dynamical systems model of peptide optimization by MHC class I. We incorporate the chaperone molecule tapasin, which has been shown to enhance peptide optimization to different extents for different MHC class I alleles. Using a combination of published and novel experimental data to parameterize the model, we arrive at a relation of peptide filtering, which quantifies peptide optimization as a function of peptide supply and peptide unbinding rates. From this relation, we find that tapasin enhances peptide unbinding to improve peptide optimization without significantly delaying the transit of MHC to the cell surface, and differences in peptide optimization across MHC class I alleles can be explained by allele-specific differences in peptide binding. Importantly, our filtering relation may be used to dynamically predict the cell surface abundance of any number of competing peptides by MHC class I alleles, providing a quantitative basis to investigate viral infection or disease at the cellular level. We exemplify this by simulating optimization of the distribution of peptides derived from Human Immunodeficiency Virus Gag-Pol polyprotein. PMID:22022238

  14. Feature-preserving optimization for noisy mesh using joint bilateral filter and constrained Laplacian smoothing

    NASA Astrophysics Data System (ADS)

    Wei, Mingqiang; Shen, Wuyao; Qin, Jing; Wu, Jianhuang; Wong, Tien-Tsin; Heng, Pheng-Ann

    2013-11-01

    Advanced 3D optical and laser scanners can generate mesh models with high-resolution details, while inevitably introducing noises from various sources and mesh irregularity due to inconsistent sampling. Noises and irregularity of a scanned model prohibit its use in practical applications where high quality models are required. However, optimizing a noisy mesh while preserving its geometric features is a challenging task. We present a robust two-step approach to meet the challenges of noisy mesh optimization. In the first step, we propose a joint bilateral filter to remove noises on a mesh while maintaining its volume and preserving its features. In the second step, we develop a constrained Laplacian smoothing scheme by adding two kinds of constraints into the original Laplacian equation. As most noises have been removed in the first step, we can easily detect feature edges from the model and add them as constraints in the Laplacian smoothing. As a result, the constrained scheme can simultaneously preserve sharp features and avoid volume shrinkage during mesh smoothing. By integrating these two steps, our approach can effectively remove noises, maintain features, improve regularity for a noisy mesh, as well as avoid side-effects such as volume shrinkage. Extensive qualitative and quantitative experiments have been performed on meshes with synthetic and raw noises to demonstrate the feasibility and effectiveness of our approach.

  15. Automatic Synthesis of Filters to Discard Buffer Overflow Attacks: A Step Towards Realizing Self-Healing Systems

    E-print Network

    Sekar, R.

    Automatic Synthesis of Filters to Discard Buffer Overflow Attacks: A Step Towards Realizing Self-Healing that it generated accurate filters for 7 out of these 8 attacks. 1 Introduction Self-healing is emerging- ploit the same vulnerability. An important benefit of self-healing is that it avoids system resources

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

    PubMed

    McMinn, Brian R

    2013-11-01

    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

  17. On the optimal and suboptimal nonlinear filtering problem for discrete-time systems

    Microsoft Academic Search

    M. L. ANDRADE NETTO; L. Gimeno; M. J. MENDES

    1978-01-01

    This paper examines optimal and suboptimal algorithms for the state filtering problem in discrete-time nonlinear systems. The optimal equations of sequential filtering are analyzed and conditions are obtained which ensure a multimodal character for the a posteriori densities. This analysis is utilized in the discussion of the performance of suboptimal linearized filters, and suggestions are made for their improvement in

  18. Video object tracing based on particle filter with ant colony optimization

    Microsoft Academic Search

    Zhou Hao; Xuejie Zhang; Pengfei Yu; Haiyan Li

    2010-01-01

    Classical particle filter needs large numbers of samples to properly approximate the posterior density of the state evolution. Furthermore, sample impoverishment is an inevitable problem, which is a key issue in the performance of a particle filter. In this paper, a particle filtering algorithm based on ant colony optimization (ACO) was proposed to enhance the performance of particle filter with

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

    E-print Network

    Trumpf, Jochen

    (EKF). Our results indicate that the proposed filter achieves better robustness against a range.g. the Extended Kalman Filter (EKF) [3]. Other meth- ods such as particle filters [4] or the Unscented Kalman1 Near-Optimal deterministic filtering on the Rotation Group Mohammad Zamani, Jochen Trumpf, Member

  20. Tri-band superconducting filter using stub-loaded stepped-impedance resonators

    NASA Astrophysics Data System (ADS)

    Feng, Yuning; Guo, Xubo; Wei, Bin; Zhang, Xiaoping; Song, Fei; Xu, Zhan; Cao, Bisong

    2015-05-01

    A stub-loaded stepped-impedance resonator (SLSIR) with three resonant modes is proposed to design a tri-band bandpass filter (BPF). The couplings between adjacent resonators at different resonant modes can be controlled independently by properly selecting the geometric parameters of the resonator. A dual-feeding structure is used to realize the required external couplings of the three passbands simultaneously. A fourth-order tri-band BPF with the passbands centered at 1.73, 2.40 and 3.45 GHz, respectively, is successfully designed and fabricated with superconducting thin films. The measured results exhibit high performance and agree well with the simulated ones.

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

    NASA Astrophysics Data System (ADS)

    Semwal, Girish; Rastogi, Vipul

    2014-01-01

    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.

  2. Multi-Step Gradient Methods for Networked Optimization

    NASA Astrophysics Data System (ADS)

    Ghadimi, Euhanna; Shames, Iman; Johansson, Mikael

    2013-11-01

    We develop multi-step gradient methods for network-constrained optimization of strongly convex functions with Lipschitz-continuous gradients. Given the topology of the underlying network and bounds on the Hessian of the objective function, we determine the algorithm parameters that guarantee the fastest convergence and characterize situations when significant speed-ups can be obtained over the standard gradient method. Furthermore, we quantify how the performance of the gradient method and its accelerated counterpart are affected by uncertainty in the problem data, and conclude that in most cases our proposed method outperforms gradient descent. Finally, we apply the proposed technique to three engineering problems: resource allocation under network-wide budget constraints, distributed averaging, and Internet congestion control. In all cases, we demonstrate that our algorithm converges more rapidly than alternative algorithms reported in the literature.

  3. Optimal filter design subject to output delobe constraints

    NASA Technical Reports Server (NTRS)

    Fortmann, T. E.; Athans, M.

    1972-01-01

    The design of filters for detection and estimation in radar and communications systems is considered, with inequality constraints on the maximum output sidelobe levels. A constrained optimization problem in Hilbert space is formulated, incorporating the sidelobe constraints via a partial ordering of continuous functions. Generalized versions (in Hilbert space) of the Kuhn-Tucker and Duality Theorems allow the reduction of this problem to an unconstrained one in the dual space of regular Borel measures. A convergent algorithm is presented for computational solution of the dual problem.

  4. Neuromuscular fiber segmentation through particle filtering and discrete optimization

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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.

  5. Optimal design of wide band low loss SAW filters, using slanted interdigital transducers

    Microsoft Academic Search

    S. M. Balashov; K. H. Baek

    2000-01-01

    Slanted finger SAW transducers allow one to design wide band filters with excellent characteristics. One of the most interesting modifications of such a filter is the slanted SPUDT. We present an approach to the analysis of such filters based on consistent use of the Y-matrix instead of the conventional P-matrix. Conditions of optimal matching of such SPUDT are obtained and

  6. Synthesizing Optimal Filters for Crosstalk-cancellation for High-Speed Buses

    E-print Network

    Greenstreet, Mark

    Synthesizing Optimal Filters for Crosstalk-cancellation for High-Speed Buses Jihong Ren and Mark in crosstalk cancellation for high-bandwidth, digital commu- nication. In practice, filter design the structure of a typical channel with a pre-equalization filter for crosstalk cancellation

  7. Optimal Personalized Filtering Against Spear-Phishing Attacks Aron Laszka and Yevgeniy Vorobeychik and Xenofon Koutsoukos

    E-print Network

    Vorobeychik, Eugene

    Optimal Personalized Filtering Against Spear-Phishing Attacks Aron Laszka and Yevgeniy Vorobeychik, attackers can use spear phishing to sidestep technical security mech- anisms by exploiting the privileges-user filtering thresholds for mitigating spear-phishing attacks. We formulate the problem of filtering targeted

  8. Simultaneous learning and filtering without delusions: a Bayes-optimal combination of Predictive Inference and Adaptive Filtering

    PubMed Central

    Kneissler, Jan; Drugowitsch, Jan; Friston, Karl; Butz, Martin V.

    2015-01-01

    Predictive coding appears to be one of the fundamental working principles of brain processing. Amongst other aspects, brains often predict the sensory consequences of their own actions. Predictive coding resembles Kalman filtering, where incoming sensory information is filtered to produce prediction errors for subsequent adaptation and learning. However, to generate prediction errors given motor commands, a suitable temporal forward model is required to generate predictions. While in engineering applications, it is usually assumed that this forward model is known, the brain has to learn it. When filtering sensory input and learning from the residual signal in parallel, a fundamental problem arises: the system can enter a delusional loop when filtering the sensory information using an overly trusted forward model. In this case, learning stalls before accurate convergence because uncertainty about the forward model is not properly accommodated. We present a Bayes-optimal solution to this generic and pernicious problem for the case of linear forward models, which we call Predictive Inference and Adaptive Filtering (PIAF). PIAF filters incoming sensory information and learns the forward model simultaneously. We show that PIAF is formally related to Kalman filtering and to the Recursive Least Squares linear approximation method, but combines these procedures in a Bayes optimal fashion. Numerical evaluations confirm that the delusional loop is precluded and that the learning of the forward model is more than 10-times faster when compared to a naive combination of Kalman filtering and Recursive Least Squares. PMID:25983690

  9. Optimal Filtering in Mass Transport Modeling From Satellite Gravimetry Data

    NASA Astrophysics Data System (ADS)

    Ditmar, P.; Hashemi Farahani, H.; Klees, R.

    2011-12-01

    Monitoring natural mass transport in the Earth's system, which has marked a new era in Earth observation, is largely based on the data collected by the GRACE satellite mission. Unfortunately, this mission is not free from certain limitations, two of which are especially critical. Firstly, its sensitivity is strongly anisotropic: it senses the north-south component of the mass re-distribution gradient much better than the east-west component. Secondly, it suffers from a trade-off between temporal and spatial resolution: a high (e.g., daily) temporal resolution is only possible if the spatial resolution is sacrificed. To make things even worse, the GRACE satellites enter occasionally a phase when their orbit is characterized by a short repeat period, which makes it impossible to reach a high spatial resolution at all. A way to mitigate limitations of GRACE measurements is to design optimal data processing procedures, so that all available information is fully exploited when modeling mass transport. This implies, in particular, that an unconstrained model directly derived from satellite gravimetry data needs to be optimally filtered. In principle, this can be realized with a Wiener filter, which is built on the basis of covariance matrices of noise and signal. In practice, however, a compilation of both matrices (and, therefore, of the filter itself) is not a trivial task. To build the covariance matrix of noise in a mass transport model, it is necessary to start from a realistic model of noise in the level-1B data. Furthermore, a routine satellite gravimetry data processing includes, in particular, the subtraction of nuisance signals (for instance, associated with atmosphere and ocean), for which appropriate background models are used. Such models are not error-free, which has to be taken into account when the noise covariance matrix is constructed. In addition, both signal and noise covariance matrices depend on the type of mass transport processes under investigation. For instance, processes of hydrological origin occur at short time scales, so that the input time series is typically short (1 month or less), which implies a relatively strong noise in the derived model. On the contrary, study of a long-term ice mass depletion requires a long time series of satellite data, which leads to a reduction of noise in the mass transport model. Of course, the spatial pattern (and therefore, the signal covariance matrices) of various mass transport processes are also very different. In the presented study, we compare various strategies to build the signal and noise covariance matrices in the context of mass transport modeling. In this way, we demonstrate the benefits of an accurate construction of an optimal filter as outlined above, compared to simplified strategies. Furthermore, we consider both models based on GRACE data alone and combined GRACE/GOCE models. In this way, we shed more light on a potential synergy of the GRACE and GOCE satellite mission. This is important nor only for the best possible mass transport modeling on the basis of all available data, but also for the optimal planning of future satellite gravity missions.

  10. Wide-Field, Motion-Sensitive Neurons and Optimal Matched Filters for Optic Flow

    Microsoft Academic Search

    Matthias O. Franz; Holger G. Krapp

    1998-01-01

    . We present a theory for the construction of an optimal matched filter for self-motion inducedoptic flow fields. The matched filter extracts local flow components along a set of pre-defined directionsand weights them according to an optimization principle which minimizes the difference between estimatedand real egomotion parameters. In contrast to previous approaches, prior knowledge about distance andtranslation statistics is incorporated

  11. Optimizing gain and noise performance of EDFAs with insertion of a filter or an isolator

    Microsoft Academic Search

    Jorn Hedegaard Povlsen; Anders Bjarklev; Ole Lumholt; Helle Vendeltorp-Pommer; Karsten Rottwitt; Thomas P. Rasmussen

    1992-01-01

    Filters and isolators placed within EDFAs can be used to increase the gain and decrease the noise figure. By use of an accurate model the placement of the filters and isolators is optimized. The optimization is performed for situations with pump lasers emitting at 0.980 micrometers and 1.480 micrometers , and signal wavelengths at either the emission cross section peak

  12. Managing microgrids with intermittent resources: A two-layer multi-step optimal control approach

    Microsoft Academic Search

    Dinghuan Zhu; Rui Yang; Gabriela Hug-Glanzmann

    2010-01-01

    A novel multi-step coordinated control approach for microgrid management is proposed considering economic and environmental aspects. The proposed concept consists of a two-layer control algorithm, the component-layer and the top-layer controls. Both are based on look-ahead multi-step optimization techniques. Assuming the availability of renewable power forecasting methods, future states of the microgrid are taken into account in the multi-step optimization.

  13. Three-Dimensional Micro Propeller Design by Using Efficient Two Step Optimization

    Microsoft Academic Search

    Ki-Hak Lee; Yong-Hee Jeon; Kyu-Hong Kim; Dong-Ho Lee; Kyung-Tae Lee

    2007-01-01

    A practical and efficient optimal design procedure is presented for three-dimensional micro-propeller. To manage many design related variables and operating conditions efficiently, the design procedure consists of two steps for optimization of operating conditions and blade geometries. First, operating condition points are extracted from the design-of-experiments, and provided as the input data of the geometry optimization step. Next, in the

  14. Optimization of continuous tube motion and step-and-shoot motion in digital breast tomosynthesis systems with patient motion

    NASA Astrophysics Data System (ADS)

    Acciavatti, Raymond J.; Maidment, Andrew D. A.

    2012-03-01

    In digital breast tomosynthesis (DBT), a reconstruction of the breast is generated from projections acquired over a limited range of x-ray tube angles. There are two principal schemes for acquiring projections, continuous tube motion and step-and-shoot motion. Although continuous tube motion has the benefit of reducing patient motion by lowering scan time, it has the drawback of introducing blurring artifacts due to focal spot motion. The purpose of this work is to determine the optimal scan time which minimizes this trade-off. To this end, the filtered backprojection reconstruction of a sinusoidal input is calculated. At various frequencies, the optimal scan time is determined by the value which maximizes the modulation of the reconstruction. Although prior authors have studied the dependency of the modulation on focal spot motion, this work is unique in also modeling patient motion. It is shown that because continuous tube motion and patient motion have competing influences on whether scan time should be long or short, the modulation is maximized by an intermediate scan time. This optimal scan time decreases with object velocity and increases with exposure time. To optimize step-and-shoot motion, we calculate the scan time for which the modulation attains the maximum value achievable in a comparable system with continuous tube motion. This scan time provides a threshold below which the benefits of step-and-shoot motion are justified. In conclusion, this work optimizes scan time in DBT systems with patient motion and either continuous tube motion or step-and-shoot motion by maximizing the modulation of the reconstruction.

  15. Sparsity Optimization in Design of Multidimensional Filter Networks

    E-print Network

    2014-11-22

    general structure. Its efficiency is demonstrated by designing certain 2D and 3D filter networks. ... Least-Squares Problem; Filter networks; Medical imaging. ...... Dudgeon DE, Mersereau RM (1990) Multidimensional digital signal processing.

  16. Tuning of PID Controller Using Internal Model Control with the Filter Constant Optimized Using Bee Colony Optimization Technique

    NASA Astrophysics Data System (ADS)

    Banu, U. Sabura; Uma, G.

    The present research work presents a novel control scheme for tuning PID controllers using Internal Model control with the filter time constant optimized using Bee colony Optimization technique. PID controllers are used widely in Industrial Processes. Tuning of PID controllers is accomplished using Internal Model control scheme. IMC includes tuning of filter constant ?. Compromise is made in selecting the filter constant ? since an increased value of ? results in a sluggish response whereas decreased value of filter constant leads in an aggressive action. In the present work, an attempt has been made to optimize the value of the ? by Bee colony optimization technique. Simulation results show the validity of the proposed scheme for the PID controller tuning.

  17. Photorefractive two-beam coupling optimal thresholding filter for additive signal-dependent noise reduction

    NASA Astrophysics Data System (ADS)

    Fu, Jack; Khoury, Jehad; Cronin-Golomb, Mark; Woods, Charles L.

    1995-01-01

    Computer simulations of photorefractive thresholding filters for the reduction of artifact or dust noise demonstrate an increase in signal-to-noise ratio (SNR) of 70% to 95%, respectively, of that provided by the Wiener filter for inputs with a SNR of approximately 3. These simple, nearly optimal filters use a spectral thresholding profile that is proportional to the envelope of the noise spectrum. Alternative nonlinear filters with either 1/ nu or constant thresholding profiles increase the SNR almost as much as the noise-envelope thresholding filter.

  18. Finite-element modeling for the design optimization of microwave filters

    Microsoft Academic Search

    S. Bila; D. Baillargeat; M. Aubourg; S. Verdeyme; F. Seyfert; L. Baratchart; C. Boichon; F. Thevenon; J. Puech; C. Zanchi; L. Lapierre; J. Sombrin

    2004-01-01

    This paper outlines an electromagnetic optimization technique dedicated to the design of microwave bandpass filters. The purpose is to determine the optimal dimensions of the electromagnetic model. Applying this technique, the geometrical dimensions of the distributed structure are accurately determined, and no experimental readjustment is necessary. The optimization procedure combines an electromagnetic analysis and a parameter extraction. The analysis method

  19. Single step optimization of feedback-decoupled spacecraft attitude maneuvers

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    A next-state optimization technique for monitoring spacecraft maneuvers is examined. The optimization technique permits simultaneous trajectory planning and tracking, incorporates actuator saturation and attitude constraints, and prevents overshoot and undershoot. The global linearization of the dynamics and kinematics for a spacecraft driven by reaction wheels is considered. The equations utilized to derive the spacecraft trajectories are presented. The applications of the next-state optimization procedure to a spacecraft maneuvered by momentum transfer devices and the tracking of the nominal trajectory of a critically damped harmonic oscillator response are described.

  20. Micro-machined tunable optical filters with optimized band-pass spectrum

    Microsoft Academic Search

    D. Hohlfeld; H. Zappe

    2003-01-01

    A novel MEMS-based tunable optical filter structure is presented which for the first time combines the advantages of an optimized filter shape function with tunability. Such a filter is essential for monitoring and reconfiguration of optical communication networks. The device is based on a Fabry-Perot interferometer employing multiple solid-state silicon cavities and dielectric Bragg mirrors. It is fabricated as a

  1. OPTIMAL SPATIAL FILTERING FOR AUDITORY STEADY-STATE RESPONSE DETECTION USING HIGH-DENSITY EEG

    E-print Network

    OPTIMAL SPATIAL FILTERING FOR AUDITORY STEADY-STATE RESPONSE DETECTION USING HIGH-DENSITY EEG, spatial filter- ing, multi-channel EEG. 1. INTRODUCTION Auditory steady-state responses (ASSRs implants' The scientific responsibility is assumed by its authors. with the same frequency. Modulation

  2. An Evaluation of a Pilot Model Based on Kalman Filtering and Optimal Control

    Microsoft Academic Search

    RODNEY D. WIERENGA

    1969-01-01

    A pilot model based on Kalman filtering and optimal control is given which, because of its structure, provides for estimation of the plant state variables, the forcing functions, the time delay, and the neuromuscular lag. The inverse filter and control problem is considered where the noise and cost function parameters yield a frequency response which is in close agreement with

  3. PWM Inverter Output Filter Cost to Losses Trade Off and Optimal Design

    E-print Network

    Paris-Sud XI, Université de

    PWM Inverter Output Filter Cost to Losses Trade Off and Optimal Design Robert J. Pasterczyk Jean--This paper describes how to design the output filter of a PWM inverter used in a Uninterruptible Power SupplyVA 3-ph. PWM inverter is taken as example. B. Design Constraints Uninterruptible Power Supply (UPS

  4. A `gammachirp' function as an optimal auditory filter with the Mellin transform

    Microsoft Academic Search

    IRINO Toshio; Morinosato Wakamiya

    1996-01-01

    A `gammachirp' function has been derived as an optimal auditory filter function in terms of minimal uncertainty in a joint time and modified-scale representation if the scale transform defined by Cohen (1989) is used in the auditory system. The gammatone function, which is widely used as the impulse response of a linear auditory filter, is a first-order approximation of the

  5. Particle filter based on Particle Swarm Optimization resampling for vision tracking

    Microsoft Academic Search

    Jing Zhao; Zhiyuan Li

    2010-01-01

    Particle filter is a powerful tool for vision tracking based on Sequential Monte Carlo framework. The core of particle filter in vision tracking is how to allocate particles to a high posterior area. Particle Swarm Optimization (PSO) is applied to find high likelihood area in this paper. PSO algorithm can search the sample area around the last time object position

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

    E-print Network

    Cunningham, Brian

    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

  7. Inertial measurement unit calibration using Full Information Maximum Likelihood Optimal Filtering

    E-print Network

    Thompson, Gordon A. (Gordon Alexander)

    2005-01-01

    The robustness of Full Information Maximum Likelihood Optimal Filtering (FIMLOF) for inertial measurement unit (IMU) calibration in high-g centrifuge environments is considered. FIMLOF uses an approximate Newton's Method ...

  8. 14:30 Yuan Cheng (Numerische Mathematik) A Particle Filter based on Optimal Transportation

    E-print Network

    Baer, Christian

    particle filter based on optimal transportation that relaxes this trade-off . 15:00 Sathej Gopalakrishnan infection The human immunodeficiency virus (HIV) targets the human immune system leading to Acquired

  9. Hamiltonian Approach to Linear Continuous-Time Singularly Perturbed Optimal Control and Filtering Problems

    Microsoft Academic Search

    Zoran Gajic; Myo-Taeg Lim

    In this paper we present a unified approach for optimal control and filtering of linear continuous-time sin- gularly perturbed linear systems that facilitates complete and exact decomposition of optimal control and filtering tasks into pure-slow and pure-fast time scales. The presented methodol- ogy eliminates numerical ill-conditioning of the original singu- larly perturbed problems, introduces parallelism into the design procedures, allows

  10. Optimized cut of LiTaO3 for resonator filters with improved performance

    Microsoft Academic Search

    N. Naumenko; B. Abbot

    2002-01-01

    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%

  11. Fast split-step wavelet collocation method for WDM system parameter optimization

    Microsoft Academic Search

    Tristan Kremp; Wolfgang Freude

    2005-01-01

    To meet rapidly increasing bandwidth requirements, extensive numerical simulations are an important optimization step for optical networks. Using a basis of cardinal functions with compact support, a new split-step wavelet collocation method (SSWCM) was developed as a general solver for the nonlinear Schrödinger equation describing pulse propagation in nonlinear optical fibers. With N as the number of discretization points, this

  12. Time-Step Optimal Broadcasting in 3-D Meshes with Minimum Total Communication Distance

    E-print Network

    Wu, Jie

    Time-Step Optimal Broadcasting in 3-D Meshes with Minimum Total Communication Distance Songluan operations. Keywords: Broadcast, communication distance, divide-and-conquer, meshes, optimization prob- lems which include multicast and broadcast. Multicast is an important system-level communication service 3, 8

  13. Optimal realizable filters and the minimum Euclidean distance principle. [for spatial light modulators

    NASA Technical Reports Server (NTRS)

    Juday, Richard D.

    1993-01-01

    Minimizing a Euclidean distance in the complex plane optimizes a wide class of correlation metrics for filters implemented on realistic devices. The algorithm searches over no more than two real scalars (gain and phase). It unifies a variety of previous solutions for special cases (e.g., a maximum signal-to-noise ratio with colored noise and a real filter and a maximum correlation intensity with no noise and a coupled filter). It extends optimal partial information filter theory to arbitrary spatial light modulators (fully complex, coupled, discrete, finite contrast ratio, and so forth), additive input noise (white or colored), spatially nonuniform filter modulators, and additive correlation detection noise (including signal dependent noise).

  14. Sequential Optimal Attitude Recursion Filter John A. Christian

    E-print Network

    Lightsey, Glenn

    of Texas at Austin, Austin, Texas 78758 DOI: 10.2514/1.49561 A new nonlinear attitude filter called profile matrix E = expected value operator ei = ith unit vector observation F = Fisher information matrix

  15. Design and performance optimization of fiber optic adaptive filters

    Microsoft Academic Search

    Palacharla Paparao; Anjan Ghosh; Susan D. Allen

    1991-01-01

    The design of the least-mean-square algorithm-based fiber optic adaptive filters for processing guided lightwave signals in real time is described. Fiber optic adaptive filters can learn to change their parameters or to process a set of characteristics of the input signal. The realization employs as few electronic devices as possible and uses optical computation to utilize the advantages of optics

  16. Optimal mismatched filter design for radar ranging, detection, and resolution

    Microsoft Academic Search

    ROBERT J. McAULAY; J. Johnson

    1971-01-01

    In a multiple-target environment a radar signal processor often uses weighting filters that are not matched to the transmitted waveform. In this paper the mean-square range-estimation error, the detection Signal-to-noise ratio (SNR), and the effects of sidelobes are expressed in terms of the impulse response of an arbitrary mismatched filter. It is desired to find that impulse response that results

  17. A two-step crushed lava rock filter unit for grey water treatment at household level in an urban slum.

    PubMed

    Katukiza, A Y; Ronteltap, M; Niwagaba, C B; Kansiime, F; Lens, P N L

    2014-01-15

    Decentralised grey water treatment in urban slums using low-cost and robust technologies offers opportunities to minimise public health risks and to reduce environmental pollution caused by the highly polluted grey water i.e. with a COD and N concentration of 3000-6000 mg L(-1) and 30-40 mg L(-1), respectively. However, there has been very limited action research to reduce the pollution load from uncontrolled grey water discharge by households in urban slums. This study was therefore carried out to investigate the potential of a two-step filtration process to reduce the grey water pollution load in an urban slum using a crushed lava rock filter, to determine the main filter design and operation parameters and the effect of intermittent flow on the grey water effluent quality. A two-step crushed lava rock filter unit was designed and implemented for use by a household in the Bwaise III slum in Kampala city (Uganda). It was monitored at a varying hydraulic loading rate (HLR) of 0.5-1.1 m d(-1) as well as at a constant HLR of 0.39 m d(-1). The removal efficiencies of COD, TP and TKN were, respectively, 85.9%, 58% and 65.5% under a varying HLR and 90.5%, 59.5% and 69%, when operating at a constant HLR regime. In addition, the log removal of Escherichia coli, Salmonella spp. and total coliforms was, respectively, 3.8, 3.2 and 3.9 under the varying HLR and 3.9, 3.5 and 3.9 at a constant HLR. The results show that the use of a two-step filtration process as well as a lower constant HLR increased the pollutant removal efficiencies. Further research is needed to investigate the feasibility of adding a tertiary treatment step to increase the nutrients and microorganisms removal from grey water. PMID:24388927

  18. Design of oversampled DFT modulated filter banks optimized for acoustic echo cancellation

    Microsoft Academic Search

    Qin Li; Wei-Ge Chen; Chao He; Henrique S. Malvar

    2009-01-01

    This paper describes a method for designing oversampled DFT filter banks (FB) optimized for subband acoustic echo cancellation (AEC). For this application, the design require- ments typically are good echo cancellation quality, low delay, small reconstruction error, and low computation complexity. Our method explicitly includes a model for echo return loss enhancement (ERLE) as part of the optimization criteria. Convergence

  19. A novel finite-wordlength particle swarm optimization technique for FRM IIR digital filters

    Microsoft Academic Search

    Seyyed Ali Hashemi; Behrouz Nowrouzian

    2011-01-01

    A novel technique is presented for finite-wordlength (FW) particle swarm optimization (PSO) of BIBO stable FRM digital filters incorporating bilinear-LDI IIR interpolation subfil- ters. A novel LUT scheme is developed to ensure that the FWPSO automatically searches over permissible FW multiplier coefficient values only in the course of optimization. The salient feature of the proposed LUT scheme is that unlike

  20. A note on optimal filtering in the presence of unknown biases

    NASA Technical Reports Server (NTRS)

    Joshi, S. M.

    1975-01-01

    This note considers some aspects of the optimal filtering problem for linear processes in the presence of unknown biases in the input and the observations. It is proved via duality that the optimal filtering problem in the presence of an input bias is equivalent to a certain optimal regulator problem incorporating integral feedback. The question of observability of the augmented system used in the state and bias estimation is answered by deriving necessary and sufficient conditions when bias is present (1) in the input, (2) in the observations and (3) both in the input and the observations.

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

    SciTech Connect

    Sun, W Y [Lawrence Berkeley Lab., CA (United States)

    1993-04-01

    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.

  2. Optimization of the fine structure and flow behavior of anisotropic porous filters, synthesized by SLS method

    NASA Astrophysics Data System (ADS)

    Shishkovsky, I.; Sherbakov, V.; Pitrov, A.

    2007-06-01

    The main goal of the work was optimization of the phase and porous fine structures of filter elements and subsequent laser synthesis by the method layer-by-layer Selective Laser Sintering (SLS) of functional devices, exploration of their properties and requirements of synthesis. Common methodical approaches are developed by the searching optimal requirements of layer-by-layer synthesis usable to different powder compositions and concrete guidelines (conditions of sintering, powder composition, etc.) for SLS of filter elements (including anisotropic) from metal-polymer powder mixture - brass + polycarbonate{PC} = 6:1. As a result of numerical simulations it designed an original graph - numerical procedure and represented a computer program for definition of flow filter performances, as homogeneous (isotropic) as heterogeneous (anisotropic), having the cylindrical shape. Calculation of flow behavior for anisotropic filter elements allows predicting their future applications and managing its.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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.

  4. Wavelet-based Image Denoising with Optimal Filter

    Microsoft Academic Search

    Yong-hwan Lee; Sang-burm Rhee

    2005-01-01

    Image denoising is basic work for image processing, analysis and computer vision. This paper proposes a novel algorithm based on wavelet threshold for image denoising, which is combined with the linear CLS (Constrained Least Squares) filtering and thresholding methods in the transform domain. We demonstrated through simulations with images contaminated by white Gaussian noise that our scheme exhibits better performance

  5. TESTING OF OPTIMAL FILTERS FOR GRAVITATIONALWAVE SIGNALS: AN EXPERIMENTAL IMPLEMENTATION

    E-print Network

    is the main tool of signal extraction for gravitational wave (GW) detectors. In gaussian noise, WK filtering implemented within the data analysis of the AURIGA ultra-cryogenic detector2 . We performed a preliminary model for the detector transfer function and noise spectrum. The experimental setup both for the room

  6. Optimal spatial filtering of real data from submarine sonar arrays

    Microsoft Academic Search

    Brian G. Ferguson; Dragana Carevic

    2010-01-01

    Submarine hydrophone arrays sample the underwater acoustic pressure field in space and time to sense the presence of sources of radiated sound and to extract tactical information from the received sounds. The outputs of the hydrophones are combined by a spatial filter (or beamformer) so that signals from a chosen direction are coherently added while the effects of noise and

  7. On optimal filtering of GPS dual frequency observations without using orbit information

    Microsoft Academic Search

    Hans-Juergen Eueler; Clyde C. Goad

    1991-01-01

    The concept of optimal filtering of observations collected with a dual frequency GPS P-code receiver is investigated in comparison\\u000a to an approach for C\\/A-code units. The filter presented here uses only data gathered between one receiver and one satellite.\\u000a The estimated state vector consists of a one-way pseudorange, ionospheric influence, and ambiguity biases. Neither orbit information\\u000a nor station information is

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

    Microsoft Academic Search

    Tsung-Shin Hsu; Ching-Lien Huang

    2010-01-01

    \\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,

  9. Low-complexity logarithmic step-size-based filtered digital backward propagation algorithm for compensating fiber transmission impairments

    NASA Astrophysics Data System (ADS)

    Asif, Rameez; Lin, Chien-Yu; Holtmannspoetter, Michael; Schmauss, Bernhard

    2012-01-01

    We have investigated a new method to reduce the complexity of the digital backward propagation algorithm (DBP). A logarithmic step-size based split-step Fourier method (SSFM) is investigated in this paper to compensate fiber transmission impairments i.e. chromatic dispersion (CD) and non-linearities (NL) in dual-polarization quadrature phase shift keying (DP-QPSK) system. The algorithm is numerically investigated for coherently-detected multiple channel DP-QPSK system over 2000km (25 spans) standard single mode fiber (SMF-28) with un-compensated transmission link. The algorithm is numerically evaluated for: (a) 20 channel 56Gbit/s (14GBaud) with 25GHz channel spacing; (b) 10 channel 112Gbit/s (28GBaud) with 50GHz channel spacing and (c) 5 channel 224Gbit/s (56GBaud) with 100GHz channel spacing. Each simulation configuration has the bandwidth occupancy of 500GHz and a total transmission capacity of 1.12Tbit/s. The logarithmic DBP algorithm (L-DBP) shows efficient results as compared to the conventional DBP method based on modified SSFM (M-DBP). The results depict efficient mitigation of CD and NL, therefore improving the non-linear threshold point (NLT) upto 4dB. Furthermore by implementing a low-pass-filter (LPF) in each SSFM step, the required number of DBP stages to compensate fiber transmission impairments can be significantly reduced (multi-span DBP) by 75% as compared to L-DBP and by 50% as compared to M-DBP. The results delineate improved system performance of logarithmic step size based filtered DBP (FL-DBP) both in terms of efficiency and complexity which will be helpful in future deployment of DBP algorithm with real-time signal processing modules for non-linear compensation.

  10. Optimal bivariate step-stress accelerated life test for Type-I hybrid censored data

    Microsoft Academic Search

    Li Ling; Wei Xu; Minghai Li

    2011-01-01

    This paper presents a step-stress accelerated life test for two stress variables to obtain optimal hold times under a Type-I hybrid censoring scheme. An exponentially distributed life and a cumulative exposure model are assumed. The maximum-likelihood estimates are given, from which the asymptotic variance and the Fisher information matrix are obtained. The optimal test plan is determined for each combination

  11. Optimal-adaptive filters for modelling spectral shape, site amplification, and source scaling

    USGS Publications Warehouse

    Safak, Erdal

    1989-01-01

    This paper introduces some applications of optimal filtering techniques to earthquake engineering by using the so-called ARMAX models. Three applications are presented: (a) spectral modelling of ground accelerations, (b) site amplification (i.e., the relationship between two records obtained at different sites during an earthquake), and (c) source scaling (i.e., the relationship between two records obtained at a site during two different earthquakes). A numerical example for each application is presented by using recorded ground motions. The results show that the optimal filtering techniques provide elegant solutions to above problems, and can be a useful tool in earthquake engineering.

  12. A GLOBALLY CONVERGENT PRIMAL-DUAL INTERIOR-POINT FILTER METHOD FOR NONLINEAR PROGRAMMING: NEW FILTER OPTIMALITY MEASURES AND COMPUTATIONAL RESULTS

    Microsoft Academic Search

    RENATA SILVA; MICHAEL ULBRICH; STEFAN ULBRICH; N. VICENTE

    In this paper we modify the original primal-dual interior-point filter method proposed in (18) for the solution of nonlinear programming problems. We introduce two new optimality filter entries based on the objective function, and thus better suited for the purposes of minimization, and propose conditions for using inexact Hessians. We show that the global convergence properties of the method remain

  13. Optimization of high-channel-count fiber Bragg grating filters design with low dispersion

    NASA Astrophysics Data System (ADS)

    Jiang, Hao; Chen, Jing; Liu, Tundong

    2015-02-01

    An optimization-based technique for high-channel-count fiber Bragg grating (FBG) filter synthesis is proposed. The approach is based on utilizing a tailored group delay to construct a mathematical optimization model. In the objective function, both the maximum index modulation and the dispersion of FBG must be optimized simultaneously. An effective evolutionary algorithm, the differential evolution (DE) algorithm, is applied to find the optimal group delay parameter. Design examples demonstrate that the proposed approach yields a remarkable reduction in maximum index modulation with low dispersion in each channel.

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

    PubMed

    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

    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

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

    PubMed Central

    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

    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

  16. Texas two-step: a framework for optimal multi-input single-output deconvolution.

    PubMed

    Neelamani, Ramesh; Deffenbaugh, Max; Baraniuk, Richard G

    2007-11-01

    Multi-input single-output deconvolution (MISO-D) aims to extract a deblurred estimate of a target signal from several blurred and noisy observations. This paper develops a new two step framework--Texas Two-Step--to solve MISO-D problems with known blurs. Texas Two-Step first reduces the MISO-D problem to a related single-input single-output deconvolution (SISO-D) problem by invoking the concept of sufficient statistics (SSs) and then solves the simpler SISO-D problem using an appropriate technique. The two-step framework enables new MISO-D techniques (both optimal and suboptimal) based on the rich suite of existing SISO-D techniques. In fact, the properties of SSs imply that a MISO-D algorithm is mean-squared-error optimal if and only if it can be rearranged to conform to the Texas Two-Step framework. Using this insight, we construct new wavelet- and curvelet-based MISO-D algorithms with asymptotically optimal performance. Simulated and real data experiments verify that the framework is indeed effective. PMID:17990752

  17. Optimization of narirutin extraction during washing step of the pectin production from citrus peels

    Microsoft Academic Search

    W. C. Kim; D. Y. Lee; C. H. Lee; C. W. Kim

    2004-01-01

    Citrus peels can be a valuable source of pectin and narirutin. Narirutin can be extracted during the washing step of citrus peels in the pectin production process. In this study narirutin extraction conditions were optimized to maximize the narirutin extraction yield while minimized pectin loss. Washing temperature, time, and HCl concentration of the washing solution were chosen as independent variables

  18. Minimizing Total Communication Distance of a Time-Step Optimal Broadcast in Mesh Networks

    E-print Network

    Wu, Jie

    Minimizing Total Communication Distance of a Time-Step Optimal Broadcast in Mesh Networks Songluan. Keywords: Broadcast, communication distance, mesh, torus. 1. Introduction In a multicomputer system for broadcast in a network is the communication time spent on sending messages from one node to all the other

  19. Non-dominated sorting genetic algorithm in optimizing ninth order multiple feedback Chebyshev low pass filter

    NASA Astrophysics Data System (ADS)

    Lim, Wei Jer; Neoh, Siew Chin; Norizan, Mohd Natashah; Mohamad, Ili Salwani

    2015-05-01

    Optimization for complex circuit design often requires large amount of manpower and computational resources. In order to optimize circuit performance, it is critical not only for circuit designers to adjust the component value but also to fulfill objectives such as gain, cutoff frequency, ripple and etc. This paper proposes Non-dominated Sorting Genetic Algorithm II (NSGA-II) to optimize a ninth order multiple feedback Chebyshev low pass filter. Multi-objective Pareto-Based optimization is involved whereby the research aims to obtain the best trade-off for minimizing the pass-band ripple, maximizing the output gain and achieving the targeted cut-off frequency. The developed NSGA-II algorithm is executed on the NGSPICE circuit simulator to assess the filter performance. Overall results show satisfactory in the achievements of the required design specifications.

  20. Optimal filtering for spike sorting of multi-site electrode recordings.

    PubMed

    Vollgraf, Roland; Munk, Matthias; Obermayer, Klaus

    2005-03-01

    We derive an optimal linear filter, to reduce the distortions of the peak amplitudes of action potentials in extracellular multitrode recordings, which are due to background activity and overlapping spikes. This filter is being learned very efficiently from the raw recordings in an unsupervised manner and responds to the average waveform with an impulse of minimal width. The average waveform does not have to be known in advance, but is learned together with the optimal filter. The peak amplitude of a filtered waveform is a more reliable estimate for the amplitude of an action potential than the peak of the biphasic waveform and can improve the accuracy of the event detection and clustering procedures. We demonstrate a spike-sorting application, in which events are detected using the Mahalanobis distance in the N-dimensional space of filtered recordings as a distance measure, and the event amplitudes of the filtered recordings are clustered to assign events to individual units. This method is fast and robust, and we show its performance by applying it to real tetrode recordings of spontaneous activity in the visual cortex of an anaesthetized cat and to realistic artificial data derived therefrom. PMID:16350435

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

    NASA Astrophysics Data System (ADS)

    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

    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.

  2. Design of optimal length low-dispersion FBG filter using covariance matrix adapted evolution

    Microsoft Academic Search

    S. Baskar; A. Alphones; P. N. Suganthan; N. Q. Ngo; R. T. Zheng

    2005-01-01

    The design of a low-dispersion fiber Bragg grating (FBG) with an optimal grating length using covariance matrix adapted evolution strategy (CMAES) is presented. A novel objective function formulation is proposed for the optimal grating length low-dispersion FBG design. The CMAES algorithm employs adaptive learning procedure to identify correlations among the design parameters. The design of a low-dispersion FBG filter with

  3. Derivative-Free Filter Simulated Annealing Method for Constrained Continuous Global Optimization

    Microsoft Academic Search

    Abdel-Rahman Hedar; Masao Fukushima

    2006-01-01

    In this paper, a simulated-annealing-based method called Filter Simulated Annealing (FSA) method is proposed to deal with\\u000a the constrained global optimization problem. The considered problem is reformulated so as to take the form of optimizing two\\u000a functions, the objective function and the constraint violation function. Then, the FSA method is applied to solve the reformulated\\u000a problem. The FSA method invokes

  4. Hair enhancement in dermoscopic images using dual-channel quaternion tubularness filters and MRF-based multilabel optimization.

    PubMed

    Mirzaalian, Hengameh; Lee, Tim K; Hamarneh, Ghassan

    2014-12-01

    Hair occlusion is one of the main challenges facing automatic lesion segmentation and feature extraction for skin cancer applications. We propose a novel method for simultaneously enhancing both light and dark hairs with variable widths, from dermoscopic images, without the prior knowledge of the hair color. We measure hair tubularness using a quaternion color curvature filter. We extract optimal hair features (tubularness, scale, and orientation) using Markov random field theory and multilabel optimization. We also develop a novel dual-channel matched filter to enhance hair pixels in the dermoscopic images while suppressing irrelevant skin pixels. We evaluate the hair enhancement capabilities of our method on hair-occluded images generated via our new hair simulation algorithm. Since hair enhancement is an intermediate step in a computer-aided diagnosis system for analyzing dermoscopic images, we validate our method and compare it to other methods by studying its effect on: 1) hair segmentation accuracy; 2) image inpainting quality; and 3) image classification accuracy. The validation results on 40 real clinical dermoscopic images and 94 synthetic data demonstrate that our approach outperforms competing hair enhancement methods. PMID:25312927

  5. Variable projection for near-optimal filtering in low bit-rate block coders

    Microsoft Academic Search

    Yaakov Tsaig; Michael Elad; Peyman Milanfar; Gene H. Golub

    2005-01-01

    Recent work on block-based compression for low bit-rate coding has shown that employing a block coder within a sampling scheme where the image is downsampled prior to coding (and upsampled after the decoding stage) results in superior per- formance compared to standard block coding. In this paper, we explore the use of optimal decimation and interpolation filters in this coding

  6. Variable projection for near-optimal filtering in low bit-rate block coders

    Microsoft Academic Search

    Yaakov Tsaig; Michael Elad; Peyman Milanfar; Gene H. Golub

    2005-01-01

    Recent work on block-based compression for low bit-rate coding has shown that employing a block coder within a sampling scheme where the image is downsampled prior to coding (and upsampled after the decoding stage) results in superior performance compared to standard block coding. We explore the use of optimal decimation and interpolation filters in this coding scheme. We show that

  7. A near-optimal filtering scheme for low bit-rate block coders using variable projection

    Microsoft Academic Search

    Yaakov Tsaig; Michael Elad; Peyman Milanfar; Gene H. Golub

    Recent work on JPEG compression for low bit-rate coding has shown that employing a JPEG coder within a sampling scheme where the image is downsampled prior to coding (and upsampled after the decoding stage) results in superior performance compared to standard JPEG coding. In this paper, we explore the use of optimal decimation and interpolation filters in this coding scheme.

  8. Spectral Filter Optimization for the Recovery of Parameters Which Describe Human Skin

    E-print Network

    Claridge, Ela

    Spectral Filter Optimization for the Recovery of Parameters Which Describe Human Skin Stephen J the error associated with histological parameters characterizing normal skin tissue. These parameters can be recovered from digital images of the skin using a physics-based model of skin coloration. The relationship

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

    E-print Network

    Evans, Brian L.

    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

  10. Optimal recursive filtering, prediction, and smoothing for singular stochastic discrete-time systems

    Microsoft Academic Search

    Huanshui Zhang; Lihua Xie; Yeng Chai Soh

    1999-01-01

    A new and simple approach to optimal recursive filtering, prediction, and smoothing for singular stochastic discrete-time systems is presented by using a time-domain innovation analysis method. The estimators are calculated based on an ARMA innovation model which can be obtained using spectral factorization or a recursive identifier. The prediction problem for the singular systems is solved with the aid of

  11. ANALYTICAL CALCULATION OF GRADIENTS FOR THE OPTIMIZATION OF HPLANE FILTERS WITH THE FEM

    E-print Network

    Bornemann, Jens

    ANALYTICAL CALCULATION OF GRADIENTS FOR THE OPTIMIZATION OF H­PLANE FILTERS WITH THE FEM P Abstract ­ This paper introduces a method for the analytical calculation of gradients of a cost functions circumstances, the gradient of a cost function can be calculated analytically without using finite differences

  12. Synthesizing optimal filters for crosstalk-cancellation for high-speed buses

    Microsoft Academic Search

    Jihong Ren; Mark R. Greenstreet

    2003-01-01

    We present practical algorithms for the synthesis of crosstalk cancelling equalizing filters. We examine designs optimized for the traditional l2 metric and introduce an approach based on the l? metric. We compare the two approaches for realistic buses with tight wire spacings. We show bandwidth improvements of up to a factor of 2 using crosstalk cancellation when compared with no

  13. Synthesizing optimal filters for crosstalk-cancellation for high-speed buses

    Microsoft Academic Search

    Jihong Ren; Mark Greenstreet

    2003-01-01

    We present practical algorithms for the synthesis of crosstalk canceling equalizing filters. We examine designs optimized for the traditional l2 metric and introduce an approach based on the l? metric. We compare the two approaches for realistic buses with tight wire spacings. We show bandwidth improvements of up to a factor of 2 using crosstalk cancellation when compared with no

  14. Efficient and Accurate Optimal Linear Phase FIR Filter Design Using Opposition-Based Harmony Search Algorithm

    PubMed Central

    Saha, S. K.; Dutta, R.; Choudhury, R.; Kar, R.; Mandal, D.; Ghoshal, S. P.

    2013-01-01

    In this paper, opposition-based harmony search has been applied for the optimal design of linear phase FIR filters. RGA, PSO, and DE have also been adopted for the sake of comparison. The original harmony search algorithm is chosen as the parent one, and opposition-based approach is applied. During the initialization, randomly generated population of solutions is chosen, opposite solutions are also considered, and the fitter one is selected as a priori guess. In harmony memory, each such solution passes through memory consideration rule, pitch adjustment rule, and then opposition-based reinitialization generation jumping, which gives the optimum result corresponding to the least error fitness in multidimensional search space of FIR filter design. Incorporation of different control parameters in the basic HS algorithm results in the balancing of exploration and exploitation of search space. Low pass, high pass, band pass, and band stop FIR filters are designed with the proposed OHS and other aforementioned algorithms individually for comparative optimization performance. A comparison of simulation results reveals the optimization efficacy of the OHS over the other optimization techniques for the solution of the multimodal, nondifferentiable, nonlinear, and constrained FIR filter design problems. PMID:23844390

  15. Optimization of ecosystem model parameters through assimilating eddy covariance flux data with an ensemble Kalman filter

    Microsoft Academic Search

    Xingguo Mo; Jing M. Chen; Weimin Ju; T. Andrew Black

    2008-01-01

    Process-based terrestrial ecosystem models have been widely used to simulate carbon cycle, climate and ecosystem interactions. Some parameters used in biological functions often change seasonally and inter-annually. In this study, sequential data assimilation with an ensemble Kalman filter is designed to optimize the key parameters of the Boreal Ecosystem Producitivity Simulator (BEPS) model, taking into account the errors in the

  16. Approximate String Membership Checking: A Multiple Filter, Optimization-Based Approach

    E-print Network

    Barman, Siddharth

    Approximate String Membership Checking: A Multiple Filter, Optimization-Based Approach Chong Sun 1@cs.wisc.edu Abstract-- We consider the approximate string membership checking (ASMC) problem of extracting all the strings or substrings in a document that approximately match some string in a given dictionary. To solve

  17. Stratified Filtered Sampling in Stochastic Optimization John M. Mulvey

    E-print Network

    Mitchell, John E.

    Abstract We develop a methodology for evaluating a decision strategy generated by a stochastic optimization significant problems dictate the development of strategies for handling sequential decision-making under of a decision strategy returned by the MSO process is crucial to increasing the technology's effectiveness

  18. IIR filter design using mixed simulated annealing-deterministic optimization

    Microsoft Academic Search

    Michele L. Marchesi

    1992-01-01

    A new global optimization algorithm for electrical design is presented. It merges features from the simulated annealing algorithm and from R. Hooke's and T.A. Jeeves's pattern search method (1961). The proposed method derives from the former algorithm the ability not to be trapped in local minima, while from the latter it derives a more efficient way to search in the

  19. The optimally reconstructed design of the causal stable synthesis filters in the M-band maximally decimated filter bank system

    Microsoft Academic Search

    Der-Feng Huang

    2005-01-01

    In the traditional design of the M-band maximally decimated filter bank system, the resulting designed synthesis filters may be unstable. Based on the least square criterion and employing the calculus of variation and the spectral factorization techniques, a modified synthesis filter can be obtained. A causal stable synthesis filter bank is proposed to replace the conventional synthesis filter bank system

  20. Optimal interpolation and the Kalman filter. [for analysis of numerical weather predictions

    NASA Technical Reports Server (NTRS)

    Cohn, S.; Isaacson, E.; Ghil, M.

    1981-01-01

    The estimation theory of stochastic-dynamic systems is described and used in a numerical study of optimal interpolation. The general form of data assimilation methods is reviewed. The Kalman-Bucy, KB filter, and optimal interpolation (OI) filters are examined for effectiveness in performance as gain matrices using a one-dimensional form of the shallow-water equations. Control runs in the numerical analyses were performed for a ten-day forecast in concert with the OI method. The effects of optimality, initialization, and assimilation were studied. It was found that correct initialization is necessary in order to localize errors, especially near boundary points. Also, the use of small forecast error growth rates over data-sparse areas was determined to offset inaccurate modeling of correlation functions near boundaries.

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

    NASA Astrophysics Data System (ADS)

    Rozovskii, Boris L.; Petrov, Anton

    1999-10-01

    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.

  2. Decoupled Control Strategy of Grid Interactive Inverter System with Optimal LCL Filter Design

    NASA Astrophysics Data System (ADS)

    Babu, B. Chitti; Anurag, Anup; Sowmya, Tontepu; Marandi, Debati; Bal, Satarupa

    2013-09-01

    This article presents a control strategy for a three-phase grid interactive voltage source inverter that links a renewable energy source to the utility grid through a LCL-type filter. An optimized LCL-type filter has been designed and modeled so as to reduce the current harmonics in the grid, considering the conduction and switching losses at constant modulation index (Ma). The control strategy adopted here decouples the active and reactive power loops, thus achieving desirable performance with independent control of active and reactive power injected into the grid. The startup transients can also be controlled by the implementation of this proposed control strategy: in addition to this, optimal LCL filter with lesser conduction and switching copper losses as well as core losses. A trade-off has been made between the total losses in the LCL filter and the Total Harmonic Distortion (THD%) of the grid current, and the filter inductor has been designed accordingly. In order to study the dynamic performance of the system and to confirm the analytical results, the models are simulated in the MATLAB/Simulink environment, and the results are analyzed.

  3. Design optimization of vena cava filters: an application to dual filtration devices.

    PubMed

    Singer, Michael A; Wang, Stephen L; Diachin, Darin P

    2010-10-01

    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 a trapped model thrombus in the inferior vena cava. The location and shape of the thrombus are parametrized, 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 the thrombus trapped along the cava wall reduces the disruption to the flow but increases the area exposed to low wall shear stress. Computer-based design optimization is a useful tool for developing vena cava filters. Characterizing and parametrizing 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. PMID:20887016

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

    SciTech Connect

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

    2009-12-03

    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.

  5. JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 21, NO. 1, JANUARY 2003 61 Optimization of the Split-Step Fourier Method in

    E-print Network

    Zweck, John

    --We studied the efficiency of different implementa- tions of the split-step Fourier method for solving simulation, optical propagation, optical solitons, software peformance, split-step Fourier method (SSFMJOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 21, NO. 1, JANUARY 2003 61 Optimization of the Split-Step

  6. Miniaturized bandpass filter using a meandered stepped-impedance resonator with a meandered-line stub-load on a GaAs substrate.

    PubMed

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

    2014-01-01

    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

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

    PubMed Central

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

    2014-01-01

    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

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

    Microsoft Academic Search

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

    2002-01-01

    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,

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

    Microsoft Academic Search

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

    2003-01-01

    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,

  10. Optimization of single-step tapering amplitude and energy detuning for high-gain FELs

    NASA Astrophysics Data System (ADS)

    Li, He-Ting; Jia, Qi-Ka

    2015-01-01

    We put forward a method to optimize the single-step tapering amplitude of undulator strength and initial energy tuning of electron beam to maximize the saturation power of high gain free-electron lasers (FELs), based on the physics of longitudinal electron beam phase space. Using the FEL simulation code GENESIS, we numerically demonstrate the accuracy of the estimations for parameters corresponding to the linac coherent light source and the Tesla test facility.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  12. Optimized FPGA Implementation of Multi-Rate FIR Filters Through Thread Decomposition

    NASA Technical Reports Server (NTRS)

    Zheng, Jason Xin; Nguyen, Kayla; He, Yutao

    2010-01-01

    Multirate (decimation/interpolation) filters are among the essential signal processing components in spaceborne instruments where Finite Impulse Response (FIR) filters are often used to minimize nonlinear group delay and finite-precision effects. Cascaded (multi-stage) designs of Multi-Rate FIR (MRFIR) filters are further used for large rate change ratio, in order to lower the required throughput while simultaneously achieving comparable or better performance than single-stage designs. Traditional representation and implementation of MRFIR employ polyphase decomposition of the original filter structure, whose main purpose is to compute only the needed output at the lowest possible sampling rate. In this paper, an alternative representation and implementation technique, called TD-MRFIR (Thread Decomposition MRFIR), is presented. The basic idea is to decompose MRFIR into output computational threads, in contrast to a structural decomposition of the original filter as done in the polyphase decomposition. Each thread represents an instance of the finite convolution required to produce a single output of the MRFIR. The filter is thus viewed as a finite collection of concurrent threads. The technical details of TD-MRFIR will be explained, first showing its applicability to the implementation of downsampling, upsampling, and resampling FIR filters, and then describing a general strategy to optimally allocate the number of filter taps. A particular FPGA design of multi-stage TD-MRFIR for the L-band radar of NASA's SMAP (Soil Moisture Active Passive) instrument is demonstrated; and its implementation results in several targeted FPGA devices are summarized in terms of the functional (bit width, fixed-point error) and performance (time closure, resource usage, and power estimation) parameters.

  13. Rolling element bearing faults diagnosis based on optimal Morlet wavelet filter and autocorrelation enhancement

    NASA Astrophysics Data System (ADS)

    Su, Wensheng; Wang, Fengtao; Zhu, Hong; Zhang, Zhixin; Guo, Zhenggang

    2010-07-01

    The fault diagnosis of rolling element bearing is important for improving mechanical system reliability and performance. When localized fault occurs in a bearing, the periodic impulsive feature of the vibration signal appears in time domain, and the corresponding bearing characteristic frequencies (BCFs) emerge in frequency domain. However, in the early stage of bearing failures, the BCFs contain very little energy and are often overwhelmed by noise and higher-level macro-structural vibrations, an effective signal processing method would be necessary to remove such corrupting noise and interference. In this paper, a new hybrid method based on optimal Morlet wavelet filter and autocorrelation enhancement is presented. First, to eliminate the frequency associated with interferential vibrations, the vibration signal is filtered with a band-pass filter determined by a Morlet wavelet whose parameters are optimized by genetic algorithm. Then, to further reduce the residual in-band noise and highlight the periodic impulsive feature, an autocorrelation enhancement algorithm is applied to the filtered signal. In the enhanced autocorrelation envelope power spectrum, only several single spectrum lines would be left, which is very simple for operator to identify the bearing fault type. Moreover, the proposed method can be conducted in an almost automatic way. The results obtained from simulated and practical experiments prove that the proposed method is very effective for bearing faults diagnosis.

  14. Digital restoration of indium-111 and iodine-123 SPECT images with optimized Metz filters

    SciTech Connect

    King, M.A.; Schwinger, R.B.; Penney, B.C.; Doherty, P.W.; Bianco, J.A.

    1986-08-01

    A number of radiopharmaceuticals of great current clinical interest for imaging are labeled with radionuclides that emit medium- to high-energy photons either as their primary radiation, or in low abundance in addition to their primary radiation. The imaging characteristics of these radionuclides result in gamma camera image quality that is inferior to that of /sup 99m/Tc images. Thus, in this investigation /sup 111/In and /sup 123/I contaminated with approximately 4% /sup 124/I were chosen to test the hypothesis that a dramatic improvement in planar and SPECT images may be obtainable with digital image restoration. The count-dependent Metz filter is shown to be able to deconvolve the rapid drop at low spatial frequencies in the imaging system modulation transfer function (MTF) resulting from the acceptance of septal penetration and scatter in the camera window. Use of the Metz filter was found to result in improved spatial resolution as measured by both the full width at half maximum and full width at tenth maximum for both planar and SPECT studies. Two-dimensional, prereconstruction filtering with optimized Metz filters was also determined to improve image contrast, while decreasing the noise level for SPECT studies. A dramatic improvement in image quality was observed with the clinical application of this filter to SPECT imaging.

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

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

    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.

  17. Optimal spectral filtering in soliton self-frequency shift for deep-tissue multiphoton microscopy.

    PubMed

    Wang, Ke; Qiu, Ping

    2015-05-01

    Tunable optical solitons generated by soliton self-frequency shift (SSFS) have become valuable tools for multiphoton microscopy (MPM). Recent progress in MPM using 1700 nm excitation enabled visualizing subcortical structures in mouse brain in vivo for the first time. Such an excitation source can be readily obtained by SSFS in a large effective-mode-area photonic crystal rod with a 1550-nm fiber femtosecond laser. A longpass filter was typically used to isolate the soliton from the residual in order to avoid excessive energy deposit on the sample, which ultimately leads to optical damage. However, since the soliton was not cleanly separated from the residual, the criterion for choosing the optimal filtering wavelength is lacking. Here, we propose maximizing the ratio between the multiphoton signal and the n'th power of the excitation pulse energy as a criterion for optimal spectral filtering in SSFS when the soliton shows dramatic overlapping with the residual. This optimization is based on the most efficient signal generation and entirely depends on physical quantities that can be easily measured experimentally. Its application to MPM may reduce tissue damage, while maintaining high signal levels for efficient deep penetration. PMID:25950644

  18. Treatment of methyl tert-butyl ether vapors in a biotrickling filters. 2. Analysis of the rate-limiting step and behavior under transient conditions

    SciTech Connect

    Fortin, N.Y.; Deshusses, M.A. [Univ. of California, Riverside, CA (United States). Dept. of Chemical and Environmental Engineering] [Univ. of California, Riverside, CA (United States). Dept. of Chemical and Environmental Engineering

    1999-09-01

    Detailed experiments were performed with gas phase biotrickling filters treating vapors of methyl tert-butyl ether (MTBE), a gasoline additive of great environmental concern. A particular emphasis was placed on the analysis of the rate-limiting step, and it was found that the process was mostly limited by the biological reaction rather than by mass transfer. Further experiments involved the study of the dynamic behavior of the biotrickling filters under simulated field conditions. In all cases, the biotrickling filters adapted rapidly to the new conditions, and new steady states were obtained within hours. The relevance of the results and the implications as far as implementation of biotrickling filters for field MTBE treatment are discussed.

  19. Design of two-channel filter bank using nature inspired optimization based fractional derivative constraints.

    PubMed

    Kuldeep, B; Singh, V K; Kumar, A; Singh, G K

    2015-01-01

    In this article, a novel approach for 2-channel linear phase quadrature mirror filter (QMF) bank design based on a hybrid of gradient based optimization and optimization of fractional derivative constraints is introduced. For the purpose of this work, recently proposed nature inspired optimization techniques such as cuckoo search (CS), modified cuckoo search (MCS) and wind driven optimization (WDO) are explored for the design of QMF bank. 2-Channel QMF is also designed with particle swarm optimization (PSO) and artificial bee colony (ABC) nature inspired optimization techniques. The design problem is formulated in frequency domain as sum of L2 norm of error in passband, stopband and transition band at quadrature frequency. The contribution of this work is the novel hybrid combination of gradient based optimization (Lagrange multiplier method) and nature inspired optimization (CS, MCS, WDO, PSO and ABC) and its usage for optimizing the design problem. Performance of the proposed method is evaluated by passband error (?p), stopband error (?s), transition band error (?t), peak reconstruction error (PRE), stopband attenuation (As) and computational time. The design examples illustrate the ingenuity of the proposed method. Results are also compared with the other existing algorithms, and it was found that the proposed method gives best result in terms of peak reconstruction error and transition band error while it is comparable in terms of passband and stopband error. Results show that the proposed method is successful for both lower and higher order 2-channel QMF bank design. A comparative study of various nature inspired optimization techniques is also presented, and the study singles out CS as a best QMF optimization technique. PMID:25034647

  20. Optimization of EFTEM image acquisition by using elastically filtered images for drift correction.

    PubMed

    Heil, Tobias; Kohl, Helmut

    2010-06-01

    Because of its high spatial resolution, energy-filtering transmission electron microscopy (EFTEM) has become widely used for the analysis of the chemical composition of nanostructures. To obtain the best spatial resolution, the precise correction of instrumental influences and the optimization of the data acquisition procedure are very important. In this publication, we discuss a modified image acquisition procedure that optimizes the acquisition process of the EFTEM images, especially for long exposure times and measurements that are affected by large spatial drift. To alleviate the blurring of the image caused by the spatial drift, we propose to take several EFTEM images with a shorter exposure time (sub-images) and merge these sub-images afterwards. To correct for the drift between these sub-images, elastically filtered images are acquired between two subsequent sub-images. These elastically filtered images are highly suitable for spatial drift correction based on the cross-correlation method. The use of the drift information between two elastically filtered images permits to merge the drift-corrected sub-images automatically and with high accuracy, resulting in sharper edges and an improved signal intensity in the final EFTEM image. Artefacts that are caused by prominent noise-peaks in the dark reference image have been suppressed by calculating the dark reference image from three images. Furthermore, using the information given by the elastically filtered images, it is possible to drift-correct a set of EFTEM images already during the acquisition. This simplifies the post-processing for elemental mapping and offers the possibility for active drift correction using the image shift function of the microscope, leading to an increased field of view. PMID:20392564

  1. Automated Discovery of Elementary Chemical Reaction Steps Using Freezing String and Berny Optimization Methods

    E-print Network

    Suleimanov, Yury V

    2015-01-01

    We present a simple protocol which allows fully automated discovery of elementary chemical reaction steps using in cooperation single- and double-ended transition-state optimization algorithms - the freezing string and Berny optimization methods, respectively. To demonstrate the utility of the proposed approach, the reactivity of several systems of combustion and atmospheric chemistry importance is investigated. The proposed algorithm allowed us to detect without any human intervention not only "known" reaction pathways, manually detected in the previous studies, but also new, previously "unknown", reaction pathways which involve significant atom rearrangements. We believe that applying such a systematic approach to elementary reaction path finding will greatly accelerate the possibility of discovery of new chemistry and will lead to more accurate computer simulations of various chemical processes.

  2. Ridge-line optimal detector

    Microsoft Academic Search

    Pierre Gouton; Hayet Laggoune; R. K. Kouassi; Michel Paindavoine

    2000-01-01

    Image processing techniques have seen many developments in recent years. Starting from the pioneering work of Canny, Deriche developed a second order recursive filter capable of detecting stepped contours. However, there are other contour shapes that those filters struggle to detect. We describe a new optimal filter sensu Canny for detecting ridge-line contours. This is a third order recursive and

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

    PubMed

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

    2014-10-31

    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

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

    Microsoft Academic Search

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

    2006-01-01

    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

  5. Compressive Bilateral Filtering.

    PubMed

    Sugimoto, Kenjiro; Kamata, Sei-Ichiro

    2015-11-01

    This paper presents an efficient constant-time bilateral filter that produces a near-optimal performance tradeoff between approximate accuracy and computational complexity without any complicated parameter adjustment, called a compressive bilateral filter (CBLF). The constant-time means that the computational complexity is independent of its filter window size. Although many existing constant-time bilateral filters have been proposed step-by-step to pursue a more efficient performance tradeoff, they have less focused on the optimal tradeoff for their own frameworks. It is important to discuss this question, because it can reveal whether or not a constant-time algorithm still has plenty room for improvements of performance tradeoff. This paper tackles the question from a viewpoint of compressibility and highlights the fact that state-of-the-art algorithms have not yet touched the optimal tradeoff. The CBLF achieves a near-optimal performance tradeoff by two key ideas: 1) an approximate Gaussian range kernel through Fourier analysis and 2) a period length optimization. Experiments demonstrate that the CBLF significantly outperforms state-of-the-art algorithms in terms of approximate accuracy, computational complexity, and usability. PMID:26068315

  6. State estimation in large-scale open channel networks using sequential Monte Carlo methods: Optimal sampling importance resampling and implicit particle filters

    NASA Astrophysics Data System (ADS)

    Rafiee, Mohammad; Barrau, Axel; Bayen, Alexandre M.

    2013-06-01

    This article investigates the performance of Monte Carlo-based estimation methods for estimation of flow state in large-scale open channel networks. After constructing a state space model of the flow based on the Saint-Venant equations, we implement the optimal sampling importance resampling filter to perform state estimation in a case in which measurements are available at every time step. Considering a case in which measurements become available intermittently, a random-map implementation of the implicit particle filter is applied to estimate the state trajectory in the interval between the measurements. Finally, some heuristics are proposed, which are shown to improve the estimation results and lower the computational cost. In the first heuristics, considering the case in which measurements are available at every time step, we apply the implicit particle filter over time intervals of a desired size while incorporating all the available measurements over the corresponding time interval. As a second heuristic method, we introduce a maximum a posteriori (MAP) method, which does not require sampling. It will be seen, through implementation, that the MAP method provides more accurate results in the case of our application while having a smaller computational cost. All estimation methods are tested on a network of 19 tidally forced subchannels and 1 reservoir, Clifton Court Forebay, in Sacramento-San Joaquin Delta in California, and numerical results are presented.

  7. Sparse gammatone signal model optimized for English speech does not match the human auditory filters.

    PubMed

    Strahl, Stefan; Mertins, Alfred

    2008-07-18

    Evidence that neurosensory systems use sparse signal representations as well as improved performance of signal processing algorithms using sparse signal models raised interest in sparse signal coding in the last years. For natural audio signals like speech and environmental sounds, gammatone atoms have been derived as expansion functions that generate a nearly optimal sparse signal model (Smith, E., Lewicki, M., 2006. Efficient auditory coding. Nature 439, 978-982). Furthermore, gammatone functions are established models for the human auditory filters. Thus far, a practical application of a sparse gammatone signal model has been prevented by the fact that deriving the sparsest representation is, in general, computationally intractable. In this paper, we applied an accelerated version of the matching pursuit algorithm for gammatone dictionaries allowing real-time and large data set applications. We show that a sparse signal model in general has advantages in audio coding and that a sparse gammatone signal model encodes speech more efficiently in terms of sparseness than a sparse modified discrete cosine transform (MDCT) signal model. We also show that the optimal gammatone parameters derived for English speech do not match the human auditory filters, suggesting for signal processing applications to derive the parameters individually for each applied signal class instead of using psychometrically derived parameters. For brain research, it means that care should be taken with directly transferring findings of optimality for technical to biological systems. PMID:18201689

  8. A new full-Newton step O(n) infeasible interior-point algorithm for semidefinite optimization

    NASA Astrophysics Data System (ADS)

    Mansouri, H.; Roos, C.

    2009-10-01

    Interior-point methods for semidefinite optimization have been studied intensively, due to their polynomial complexity and practical efficiency. Recently, the second author designed a primal-dual infeasible interior-point algorithm with the currently best iteration bound for linear optimization problems. Since the algorithm uses only full Newton steps, it has the advantage that no line-searches are needed. In this paper we extend the algorithm to semidefinite optimization. The algorithm constructs strictly feasible iterates for a sequence of perturbations of the given problem and its dual problem, close to their central paths. Two types of full-Newton steps are used, feasibility steps and (ordinary) centering steps, respectively. The algorithm starts from strictly feasible iterates of a perturbed pair, on its central path, and feasibility steps find strictly feasible iterates for the next perturbed pair. By using centering steps for the new perturbed pair, we obtain strictly feasible iterates close enough to the central path of the new perturbed pair. The starting point depends on a positive number ?. The algorithm terminates either by finding an ?-solution or by detecting that the primal-dual problem pair has no optimal solution (X *,y *,S *) with vanishing duality gap such that the eigenvalues of X * and S * do not exceed ?. The iteration bound coincides with the currently best iteration bound for semidefinite optimization problems.

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

    PubMed Central

    Kim, Nam-Young

    2013-01-01

    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

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

    PubMed

    Dhakal, Rajendra; Kim, Nam-Young

    2013-01-01

    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

  11. Observation Density Based Static Optimization of Sensor Parameter

    Microsoft Academic Search

    Yanwen Qu; Erhua Zhang; Jingyu Yang

    2010-01-01

    Since the estimation performance of bayesian filters is largely affected by the observations, sensor management has attracted many researchers in bayesian filtering. State Prior Probability Distribution (SPPD) at each time step plays an important role in the dynamic optimization of sensor parameter. However, before all measurements came, SPPD at each time step is not available in the static optimization. In

  12. Real-time defect detection of steel wire rods using wavelet filters optimized by univariate dynamic encoding algorithm for searches.

    PubMed

    Yun, Jong Pil; Jeon, Yong-Ju; Choi, Doo-chul; Kim, Sang Woo

    2012-05-01

    We propose a new defect detection algorithm for scale-covered steel wire rods. The algorithm incorporates an adaptive wavelet filter that is designed on the basis of lattice parameterization of orthogonal wavelet bases. This approach offers the opportunity to design orthogonal wavelet filters via optimization methods. To improve the performance and the flexibility of wavelet design, we propose the use of the undecimated discrete wavelet transform, and separate design of column and row wavelet filters but with a common cost function. The coefficients of the wavelet filters are optimized by the so-called univariate dynamic encoding algorithm for searches (uDEAS), which searches the minimum value of a cost function designed to maximize the energy difference between defects and background noise. Moreover, for improved detection accuracy, we propose an enhanced double-threshold method. Experimental results for steel wire rod surface images obtained from actual steel production lines show that the proposed algorithm is effective. PMID:22561939

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

    PubMed

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

    2014-04-25

    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

  14. Optimal hydrograph separation filter to evaluate transport routines of hydrological models

    NASA Astrophysics Data System (ADS)

    Rimmer, Alon; Hartmann, Andreas

    2014-06-01

    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.

  15. Optimal estimation of missile free-flight trajectory: Comparative results of linear and nonlinear Kalman filter approaches

    Microsoft Academic Search

    F. D. Groutage

    1980-01-01

    This is a technical report on the application of optimal estimation theory for estimating the trajectory of a free-flight missile, as a means of evaluating missile performance. Several approaches were investigated (linear Kalman filter working in Cartesian Coordinates and nonlinear extended Kalman filter implemented in Cartesian Coordinates). A six-degree of freedom simulation was used to generate the free-flight trajectory of

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

    Microsoft Academic Search

    Adly Girgis; T. Daniel Hwang

    1984-01-01

    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

  17. Edge-conditioned vector basis functions for the analysis and optimization of rectangular waveguide dual-mode filters

    Microsoft Academic Search

    Jens Bornemann; Uwe Rosenberg; Smain Amari; Rudiger Vahldieck

    1999-01-01

    The reliable computer-aided design of narrowband dual-mode filters is usually hampered by extensive CPU-time and memory requirements of commercially available software packages. This paper introduces a new concept within the coupled-integral-equations-technique (CIET) which takes into account all edge conditions simultaneously and, therefore, permits the analysis and optimization of such filter components in a timely fashion. A 12.3 GHz four-pole dual-mode

  18. Filtering Light

    NSDL National Science Digital Library

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

  19. Graphics-processor-unit-based parallelization of optimized baseline wander filtering algorithms for long-term electrocardiography.

    PubMed

    Niederhauser, Thomas; Wyss-Balmer, Thomas; Haeberlin, Andreas; Marisa, Thanks; Wildhaber, Reto A; Goette, Josef; Jacomet, Marcel; Vogel, Rolf

    2015-06-01

    Long-term electrocardiogram (ECG) often suffers from relevant noise. Baseline wander in particular is pronounced in ECG recordings using dry or esophageal electrodes, which are dedicated for prolonged registration. While analog high-pass filters introduce phase distortions, reliable offline filtering of the baseline wander implies a computational burden that has to be put in relation to the increase in signal-to-baseline ratio (SBR). Here, we present a graphics processor unit (GPU)-based parallelization method to speed up offline baseline wander filter algorithms, namely the wavelet, finite, and infinite impulse response, moving mean, and moving median filter. Individual filter parameters were optimized with respect to the SBR increase based on ECGs from the Physionet database superimposed to autoregressive modeled, real baseline wander. A Monte-Carlo simulation showed that for low input SBR the moving median filter outperforms any other method but negatively affects ECG wave detection. In contrast, the infinite impulse response filter is preferred in case of high input SBR. However, the parallelized wavelet filter is processed 500 and four times faster than these two algorithms on the GPU, respectively, and offers superior baseline wander suppression in low SBR situations. Using a signal segment of 64 mega samples that is filtered as entire unit, wavelet filtering of a seven-day high-resolution ECG is computed within less than 3 s. Taking the high filtering speed into account, the GPU wavelet filter is the most efficient method to remove baseline wander present in long-term ECGs, with which computational burden can be strongly reduced. PMID:25675449

  20. Rotor cascade shape optimization with unsteady passing wakes using implicit dual time stepping method

    NASA Astrophysics Data System (ADS)

    Lee, Eun Seok

    2000-10-01

    An improved aerodynamics performance of a turbine cascade shape can be achieved by an understanding of the flow-field associated with the stator-rotor interaction. In this research, an axial gas turbine airfoil cascade shape is optimized for improved aerodynamic performance by using an unsteady Navier-Stokes solver and a parallel genetic algorithm. The objective of the research is twofold: (1) to develop a computational fluid dynamics code having faster convergence rate and unsteady flow simulation capabilities, and (2) to optimize a turbine airfoil cascade shape with unsteady passing wakes for improved aerodynamic performance. The computer code solves the Reynolds averaged Navier-Stokes equations. It is based on the explicit, finite difference, Runge-Kutta time marching scheme and the Diagonalized Alternating Direction Implicit (DADI) scheme, with the Baldwin-Lomax algebraic and k-epsilon turbulence modeling. Improvements in the code focused on the cascade shape design capability, convergence acceleration and unsteady formulation. First, the inverse shape design method was implemented in the code to provide the design capability, where a surface transpiration concept was employed as an inverse technique to modify the geometry satisfying the user specified pressure distribution on the airfoil surface. Second, an approximation storage multigrid method was implemented as an acceleration technique. Third, the preconditioning method was adopted to speed up the convergence rate in solving the low Mach number flows. Finally, the implicit dual time stepping method was incorporated in order to simulate the unsteady flow-fields. For the unsteady code validation, the Stokes's 2nd problem and the Poiseuille flow were chosen and compared with the computed results and analytic solutions. To test the code's ability to capture the natural unsteady flow phenomena, vortex shedding past a cylinder and the shock oscillation over a bicircular airfoil were simulated and compared with experiments and other research results. The rotor cascade shape optimization with unsteady passing wakes was performed to obtain an improved aerodynamic performance using the unsteady Navier-Stokes solver. Two objective functions were defined as minimization of total pressure loss and maximization of lift, while the mass flow rate was fixed. A parallel genetic algorithm was used as an optimizer and the penalty method was introduced. Each individual's objective function was computed simultaneously by using a 32 processor distributed memory computer. One optimization took about four days.

  1. Analysis of the rate-limiting step of an anaerobic biotrickling filter removing Sudeep C. Popat a

    E-print Network

    activated carbon, and catalytic oxidation [1,2]. In particular, the development of biotrickling filters has transfer. By combining the effectiveness factor with a detailed modeling of the biotrickling filtration

  2. Design of optical thin film systems for ultraviolet narrow-band interference filters based on needle optimization technique

    NASA Astrophysics Data System (ADS)

    Peng, Guanliang; Yang, Jiankun; Jia, Honghui; Chang, Shengli; Yang, Juncai

    2007-11-01

    Solar blind ultraviolet communication systems can provide short to medium range non line-of-sight and line-of-sight links which are covert and insensitive to meteorological conditions. These unique properties endow solar blind ultraviolet communication systems increasing applications. While optical filters are key components of these solar blind ultraviolet communication systems. Although filters can be designed in different forms, thin-film interference narrow-band filters are widely adopted. In this paper, we make use of NCNBIF, which was so-called nonconventional narrow-band interference filters proposed by Jerzy Ciosek firstly, to design ultraviolet narrow-band interference filters. Generally, classical narrow-band interference dielectric filters, such as Fabry-Pérot filters, have a half-wave-thickness spacer layer. In contrast with a classical interference filter, the NCNBIF does not have a half-wave-thickness spacer layer. This spacer layer of NCNBIF consists of two different materials. This new kind of film system (NCNBIF) is synthesized by using needle optimization technique, and possesses desired spectral characteristics.

  3. Effect of nonlinear three-dimensional optimized reconstruction algorithm filter on image quality and radiation dose: Validation on phantoms

    SciTech Connect

    Bai Mei; Chen Jiuhong; Raupach, Rainer; Suess, Christoph; Tao Ying; Peng Mingchen [Department of Biomedical Engineering, Xuanwu Hospital of Capital University of Medical Sciences, No. 45 Changchun Street, Beijing, 100053 (China); Siemens Medical Solutions, Beijing, 100102 (China); Siemens AG Medical Solutions, Forchheim, 91301 (Germany); Department of Biomedical Engineering, Xuanwu Hospital of Capital University of Medical Sciences, No. 45 Changchun Street, Beijing, 100053 (China)

    2009-01-15

    A new technique called the nonlinear three-dimensional optimized reconstruction algorithm filter (3D ORA filter) is currently used to improve CT image quality and reduce radiation dose. This technical note describes the comparison of image noise, slice sensitivity profile (SSP), contrast-to-noise ratio, and modulation transfer function (MTF) on phantom images processed with and without the 3D ORA filter, and the effect of the 3D ORA filter on CT images at a reduced dose. For CT head scans the noise reduction was up to 54% with typical bone reconstruction algorithms (H70) and a 0.6 mm slice thickness; for liver CT scans the noise reduction was up to 30% with typical high-resolution reconstruction algorithms (B70) and a 0.6 mm slice thickness. MTF and SSP did not change significantly with the application of 3D ORA filtering (P>0.05), whereas noise was reduced (P<0.05). The low contrast detectability and MTF of images obtained at a reduced dose and filtered by the 3D ORA were equivalent to those of standard dose CT images; there was no significant difference in image noise of scans taken at a reduced dose, filtered using 3D ORA and standard dose CT (P>0.05). The 3D ORA filter shows good potential for reducing image noise without affecting image quality attributes such as sharpness. By applying this approach, the same image quality can be achieved whilst gaining a marked dose reduction.

  4. 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

    Jeih-weih Hung; Nantou Hsien

    2007-01-01

    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

  5. Visual fidelity of bilevel halftones generated by the error diffusion filter optimized for the blue noise masks in all tone levels

    Microsoft Academic Search

    Junghyeun Hwang; Hisakazu Kikuchi; Shogo Muramatsu; Jaeho Shin

    2009-01-01

    In this paper a set of the optimum error diffusion filters is presented for the bilevel halftoning of grayscale images and the visual fidelity of the bilevel halftones generated by the error diffusion filters is investigated. The error diffusion filter is optimized with respect to the ideal blue noise mask (BNM) corresponding to a single tone level. The number of

  6. Spectral filtering optimization of a measuring channel of an x-ray broadband spectrometer

    NASA Astrophysics Data System (ADS)

    Emprin, B.; Troussel, Ph.; Villette, B.; Delmotte, F.

    2013-05-01

    A new channel of an X-ray broadband spectrometer has been developed for the 2 - 4 keV spectral range. It uses a spectral filtering by using a non-periodic multilayer mirror. This channel is composed by a filter, an aperiodic multilayer mirror and a detector. The design and realization of the optical coating mirror has been defined such as the reflectivity is above 8% in almost the entire bandwidth range 2 - 4 keV and lower than 2% outside. The mirror is optimized for working at 1.9° grazing incidence. The mirror is coated with a stack of 115 chromium / scandium (Cr / Sc) non-periodic layers, between 0.6 nm and 7.3 nm and a 3 nm thick top SiO2 layer to protect the stack from oxidization. To control thin thicknesses, we produced specific multilayer mirrors which consist on a superposition of two periodic Cr / Sc multilayers with the layer to calibrate in between. The mirror and subnanometric layers characterizations were made at the "Laboratoire Charles Fabry" (LCF) with a grazing incidence reflectometer working at 8.048 keV (Cu K? radiation) and at the synchrotron radiation facility SOLEIL on the hard X-ray branch of the "Metrology" beamline. The reflectivity of the mirrors as a function of the photon energy was obtained in the Physikalisch Technische Bundesanstalt (PTB) laboratory at the synchrotron radiation facility Bessy II.

  7. Least median of squares filtering of locally optimal point matches for compressible flow image registration.

    PubMed

    Castillo, Edward; Castillo, Richard; White, Benjamin; Rojo, Javier; Guerrero, Thomas

    2012-08-01

    Compressible flow based image registration operates under the assumption that the mass of the imaged material is conserved from one image to the next. Depending on how the mass conservation assumption is modeled, the performance of existing compressible flow methods is limited by factors such as image quality, noise, large magnitude voxel displacements, and computational requirements. The Least Median of Squares Filtered Compressible Flow (LFC) method introduced here is based on a localized, nonlinear least squares, compressible flow model that describes the displacement of a single voxel that lends itself to a simple grid search (block matching) optimization strategy. Spatially inaccurate grid search point matches, corresponding to erroneous local minimizers of the nonlinear compressible flow model, are removed by a novel filtering approach based on least median of squares fitting and the forward search outlier detection method. The spatial accuracy of the method is measured using ten thoracic CT image sets and large samples of expert determined landmarks (available at www.dir-lab.com). The LFC method produces an average error within the intra-observer error on eight of the ten cases, indicating that the method is capable of achieving a high spatial accuracy for thoracic CT registration. PMID:22797602

  8. The optimal filters for the construction of the ensemble pulsar time

    E-print Network

    Alexander E. Rodin

    2008-07-08

    The algorithm of the ensemble pulsar time based on the optimal Wiener filtration method has been constructed. This algorithm allows the separation of the contributions to the post-fit pulsar timing residuals of the atomic clock and pulsar itself. Filters were designed with the use of the cross- and autocovariance functions of the timing residuals. The method has been applied to the timing data of millisecond pulsars PSR B1855+09 and PSR B1937+21 and allowed the filtering out of the atomic scale component from the pulsar data. Direct comparison of the terrestrial time TT(BIPM06) and the ensemble pulsar time PT$_{\\rm ens}$ revealed that fractional instability of TT(BIPM06)--PT$_{\\rm ens}$ is equal to $\\sigma_z=(0.8\\pm 1.9)\\cdot 10^{-15}$. Based on the $\\sigma_z$ statistics of TT(BIPM06)--PT$_{\\rm ens}$ a new limit of the energy density of the gravitational wave background was calculated to be equal to $\\Omega_g h^2 \\sim 3\\cdot 10^{-9}$.

  9. Three-dimensional optical analyses and optimizations of a vertical alignment color-filters-embedded liquid-crystal-on-silicon microdisplay

    E-print Network

    Three-dimensional optical analyses and optimizations of a vertical alignment color-filters-dimensional optical analyses and optimizations of a vertical alignment color-filters-embedded liquid of China 2 Center for Display Research, The Hong Kong University of Science and Technology, Clear Water Bay

  10. 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

    Moon, Un-Ku

    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

  11. A new infeasible interior-point algorithm with full step for linear optimization based on a simple function

    Microsoft Academic Search

    Lipu Zhang; Yinghong Xu

    2011-01-01

    In this paper, we design and analyse an infeasible interior-point algorithm based on a simple function for linear optimization. The infeasible algorithm contains two types of search directions: the feasibility search direction and the centrality search direction. Both of the directions are determined by the simple function. The algorithm uses full step, thus no need to perform the line-search procedure.

  12. Performance of mixed-metric optimized ternary correlation filters on realistic binary and gray-scale imagery

    NASA Astrophysics Data System (ADS)

    Flannery, David L.; Phillips, William E., III; Goldstein, Dennis H.

    1993-01-01

    The ternary phase-amplitude filter (TPAF) is by definition restricted to the modulation values -1, 0, and 1, thus comprising a binary phase-only filter (BPOF) multiplied by a binary- amplitude pattern, i.e., a region of support. The TPAF offers an attractive combination of real-time implementation with available devices and good correlation performance. Smart (optimized distortion-invariant) TPAF formulations have been developed. The TPAF enables filter implementation with magneto-optic devices and these devices also can be used for image input if gray scale scenes can be binarized while preserving good correlation performance. We provide simulation results addressing the comparative performance of mixed-metric smart TPAF's using gray scale, edge-enhanced and binary images derived from identical original scenes. The variation of filter performance with training set background intensity level is examined.

  13. Optimal linear spatial filters for event-related potentials based on a spatio-temporal model: asymptotical performance analysis

    E-print Network

    Boyer, Edmond

    studies in neuroscience is addressed. The proposed framework (denoted xDAWN) has the advantage to require. A theoretical analysis of the xDAWN framework shows that it provides asymptotically optimal spatial filters methods, such as independent component analysis, in a wide range of situations. Moreover, the xDAWN

  14. Automatic Layout Optimization of an EMC filter Thomas DE OLIVEIRA, Jean-Luc SCHANEN, Jean-Michel GUICHON, Laurent GERBAUD

    E-print Network

    Paris-Sud XI, Université de

    Automatic Layout Optimization of an EMC filter Thomas DE OLIVEIRA, Jean-Luc SCHANEN, Jean to improve its behavior. A proper arrangement of components and a clever layout of tracks are required Element Circuit), in order to consider the electro-magnetic aspect in the layout definition. I

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

    NASA Technical Reports Server (NTRS)

    Stewart, Elwood C.

    1961-01-01

    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.

  16. Advances in sequential data assimilation and numerical weather forecasting: An Ensemble Transform Kalman-Bucy Filter, a study on clustering in deterministic ensemble square root filters, and a test of a new time stepping scheme in an atmospheric model

    NASA Astrophysics Data System (ADS)

    Amezcua, Javier

    This dissertation deals with aspects of sequential data assimilation (in particular ensemble Kalman filtering) and numerical weather forecasting. In the first part, the recently formulated Ensemble Kalman-Bucy (EnKBF) filter is revisited. It is shown that the previously used numerical integration scheme fails when the magnitude of the background error covariance grows beyond that of the observational error covariance in the forecast window. Therefore, we present a suitable integration scheme that handles the stiffening of the differential equations involved and doesn't represent further computational expense. Moreover, a transform-based alternative to the EnKBF is developed: under this scheme, the operations are performed in the ensemble space instead of in the state space. Advantages of this formulation are explained. For the first time, the EnKBF is implemented in an atmospheric model. The second part of this work deals with ensemble clustering, a phenomenon that arises when performing data assimilation using of deterministic ensemble square root filters in highly nonlinear forecast models. Namely, an M-member ensemble detaches into an outlier and a cluster of M-1 members. Previous works may suggest that this issue represents a failure of EnSRFs; this work dispels that notion. It is shown that ensemble clustering can be reverted also due to nonlinear processes, in particular the alternation between nonlinear expansion and compression of the ensemble for different regions of the attractor. Some EnSRFs that use random rotations have been developed to overcome this issue; these formulations are analyzed and their advantages and disadvantages with respect to common EnSRFs are discussed. The third and last part contains the implementation of the Robert-Asselin-Williams (RAW) filter in an atmospheric model. The RAW filter is an improvement to the widely popular Robert-Asselin filter that successfully suppresses spurious computational waves while avoiding any distortion in the mean value of the function. Using statistical significance tests both at the local and field level, it is shown that the climatology of the SPEEDY model is not modified by the changed time stepping scheme; hence, no retuning of the parameterizations is required. It is found the accuracy of the medium-term forecasts is increased by using the RAW filter.

  17. The Touro 12-Step: A Systematic Guide to Optimizing Survey Research with Online Discussion Boards

    PubMed Central

    Ip, Eric J; Tenerowicz, Michael J; Perry, Paul J

    2010-01-01

    The Internet, in particular discussion boards, can provide a unique opportunity for recruiting participants in online research surveys. Despite its outreach potential, there are significant barriers which can limit its success. Trust, participation, and visibility issues can all hinder the recruitment process; the Touro 12-Step was developed to address these potential hurdles. By following this step-by-step approach, researchers will be able to minimize these pitfalls and maximize their recruitment potential via online discussion boards. PMID:20507843

  18. Design of Optimal Array Processors for Two-Step Division-Free Gaussian Elimination

    Microsoft Academic Search

    Shietung PENG; Stanislav G. SEDUKHIN

    SUMMARY The design of array processors for solving lin- ear systems using two-step division-free Gaussian elimination method is considered. The two-step method can be used to im- prove the systems based on the one-step method in terms of nu- merical stability as well as the requirements for high-precision. In spite of the rather complicated computations needed at each it- eration

  19. On the sensitivity of lattice wave digital filters versus block-optimal state-space structures

    Microsoft Academic Search

    Antonio Alvarez-Vellisco

    1996-01-01

    This paper describes a study comparing, in terms of sensitivity, IIR filters produced by second order structures connected in parallel and in cascade, and Lattice Wave Digital Filters (LWDF). Simulation programs have been used(“sen-iir” for IIR filters and “sen-cel” for LWDF), from which the filter coefficient derives the multiparametric sensitivity curve in relation to frequency to obtain more satisfactory results.

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

    NASA Technical Reports Server (NTRS)

    Litt, Jonathan S.

    2007-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Litt, Jonathan S.

    2007-01-01

    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.

  2. Selection of plants for optimization of vegetative filter strips treating runoff from turfgrass.

    PubMed

    Smith, Katy E; Putnam, Raymond A; Phaneuf, Clifford; Lanza, Guy R; Dhankher, Om P; Clark, John M

    2008-01-01

    Runoff from turf environments, such as golf courses, is of increasing concern due to the associated chemical contamination of lakes, reservoirs, rivers, and ground water. Pesticide runoff due to fungicides, herbicides, and insecticides used to maintain golf courses in acceptable playing condition is a particular concern. One possible approach to mitigate such contamination is through the implementation of effective vegetative filter strips (VFS) on golf courses and other recreational turf environments. The objective of the current study was to screen ten aesthetically acceptable plant species for their ability to remove four commonly-used and degradable pesticides: chlorpyrifos (CP), chlorothalonil (CT), pendimethalin (PE), and propiconazole (PR) from soil in a greenhouse setting, thus providing invaluable information as to the species composition that would be most efficacious for use in VFS surrounding turf environments. Our results revealed that blue flag iris (Iris versicolor) (76% CP, 94% CT, 48% PE, and 33% PR were lost from soil after 3 mo of plant growth), eastern gama grass (Tripsacum dactyloides) (47% CP, 95% CT, 17% PE, and 22% PR were lost from soil after 3 mo of plant growth), and big blue stem (Andropogon gerardii) (52% CP, 91% CT, 19% PE, and 30% PR were lost from soil after 3 mo of plant growth) were excellent candidates for the optimization of VFS as buffer zones abutting turf environments. Blue flag iris was most effective at removing selected pesticides from soil and had the highest aesthetic value of the plants tested. PMID:18689747

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

    PubMed

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

    2012-03-26

    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

  4. Optimized FIR filters for digital pulse compression of biphase codes with low sidelobes

    NASA Astrophysics Data System (ADS)

    Sanal, M.; Kuloor, R.; Sagayaraj, M. J.

    In miniaturized radars where power, real estate, speed and low cost are tight constraints and Doppler tolerance is not a major concern biphase codes are popular and FIR filter is used for digital pulse compression (DPC) implementation to achieve required range resolution. Disadvantage of low peak to sidelobe ratio (PSR) of biphase codes can be overcome by linear programming for either single stage mismatched filter or two stage approach i.e. matched filter followed by sidelobe suppression filter (SSF) filter. Linear programming (LP) calls for longer filter lengths to obtain desirable PSR. Longer the filter length greater will be the number of multipliers, hence more will be the requirement of logic resources used in the FPGAs and many time becomes design challenge for system on chip (SoC) requirement. This requirement of multipliers can be brought down by clustering the tap weights of the filter by kmeans clustering algorithm at the cost of few dB deterioration in PSR. The cluster centroid as tap weight reduces logic used in FPGA for FIR filters to a great extent by reducing number of weight multipliers. Since k-means clustering is an iterative algorithm, centroid for weights cluster is different in different iterations and causes different clusters. This causes difference in clustering of weights and sometimes even it may happen that lesser number of multiplier and lesser length of filter provide better PSR.

  5. Dual-energy approach to contrast-enhanced mammography using the balanced filter method: Spectral optimization and preliminary phantom measurement

    SciTech Connect

    Saito, Masatoshi [Department of Radiological Technology, School of Health Sciences, Faculty of Medicine, Niigata University, Niigata 951-8518 (Japan)

    2007-11-15

    Dual-energy contrast agent-enhanced mammography is a technique of demonstrating breast cancers obscured by a cluttered background resulting from the contrast between soft tissues in the breast. The technique has usually been implemented by exploiting two exposures to different x-ray tube voltages. In this article, another dual-energy approach using the balanced filter method without switching the tube voltages is described. For the spectral optimization of dual-energy mammography using the balanced filters, we applied a theoretical framework reported by Lemacks et al. [Med. Phys. 29, 1739-1751 (2002)] to calculate the signal-to-noise ratio (SNR) in an iodinated contrast agent subtraction image. This permits the selection of beam parameters such as tube voltage and balanced filter material, and the optimization of the latter's thickness with respect to some critical quantity--in this case, mean glandular dose. For an imaging system with a 0.1 mm thick CsI:Tl scintillator, we predict that the optimal tube voltage would be 45 kVp for a tungsten anode using zirconium, iodine, and neodymium balanced filters. A mean glandular dose of 1.0 mGy is required to obtain an SNR of 5 in order to detect 1.0 mg/cm{sup 2} iodine in the resulting clutter-free image of a 5 cm thick breast composed of 50% adipose and 50% glandular tissue. In addition to spectral optimization, we carried out phantom measurements to demonstrate the present dual-energy approach for obtaining a clutter-free image, which preferentially shows iodine, of a breast phantom comprising three major components - acrylic spheres, olive oil, and an iodinated contrast agent. The detection of iodine details on the cluttered background originating from the contrast between acrylic spheres and olive oil is analogous to the task of distinguishing contrast agents in a mixture of glandular and adipose tissues.

  6. Optimization of the split-step Fourier method in modeling optical-fiber communications systems

    Microsoft Academic Search

    Oleg V. Sinkin; Ronald Holzlöhner; John Zweck; Curtis R. Menyuk

    2003-01-01

    We studied the efficiency of different implementations of the split-step Fourier method for solving the nonlinear Schrödinger equation that employ different step-size selection criteria. We compared the performance of the different implementations for a variety of pulse formats and systems, including higher order solitons, collisions of soliton pulses, a single-channel periodically stationary dispersion-managed soliton system, and chirped return to zero

  7. Identifying the preferred subset of enzymatic profiles in nonlinear kinetic metabolic models via multiobjective global optimization and Pareto filters.

    PubMed

    Pozo, Carlos; Guillén-Gosálbez, Gonzalo; Sorribas, Albert; Jiménez, Laureano

    2012-01-01

    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

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

    PubMed Central

    Pozo, Carlos; Guillén-Gosálbez, Gonzalo; Sorribas, Albert; Jiménez, Laureano

    2012-01-01

    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

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

    E-print Network

    Wichmann, Felix

    . In the case of transient signals, a filter has not only to detect the presence of a specific waveform, beamforming, Capon beamformer, linear filters, performance measure I. INTRODUCTION FOR detection of signals of simultaneously detecting the presence as well as estimating the arrival time of transient signals. This work

  10. Optimal filter design approaches to statistical process control for autocorrelated processes

    E-print Network

    Chin, Chang-Ho

    2005-11-01

    control charting methods can be viewed as the charting of the output of a linear filter applied to the process data. In this dissertation, we generalize the concept of linear filters for control charts and propose new control charting schemes, the general...

  11. SU-E-I-57: Evaluation and Optimization of Effective-Dose Using Different Beam-Hardening Filters in Clinical Pediatric Shunt CT Protocol

    SciTech Connect

    Gill, K; Aldoohan, S; Collier, J

    2014-06-01

    Purpose: Study image optimization and radiation dose reduction in pediatric shunt CT scanning protocol through the use of different beam-hardening filters Methods: A 64-slice CT scanner at OU Childrens Hospital has been used to evaluate CT image contrast-to-noise ratio (CNR) and measure effective-doses based on the concept of CT dose index (CTDIvol) using the pediatric head shunt scanning protocol. The routine axial pediatric head shunt scanning protocol that has been optimized for the intrinsic x-ray tube filter has been used to evaluate CNR by acquiring images using the ACR approved CT-phantom and radiation dose CTphantom, which was used to measure CTDIvol. These results were set as reference points to study and evaluate the effects of adding different filtering materials (i.e. Tungsten, Tantalum, Titanium, Nickel and Copper filters) to the existing filter on image quality and radiation dose. To ensure optimal image quality, the scanner routine air calibration was run for each added filter. The image CNR was evaluated for different kVps and wide range of mAs values using above mentioned beam-hardening filters. These scanning protocols were run under axial as well as under helical techniques. The CTDIvol and the effective-dose were measured and calculated for all scanning protocols and added filtration, including the intrinsic x-ray tube filter. Results: Beam-hardening filter shapes energy spectrum, which reduces the dose by 27%. No noticeable changes in image low contrast detectability Conclusion: Effective-dose is very much dependent on the CTDIVol, which is further very much dependent on beam-hardening filters. Substantial reduction in effective-dose is realized using beam-hardening filters as compare to the intrinsic filter. This phantom study showed that significant radiation dose reduction could be achieved in CT pediatric shunt scanning protocols without compromising in diagnostic value of image quality.

  12. IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 61, NO. 1, JANUARY 2013 139 Stepped Circular Waveguide Dual-Mode Filters for

    E-print Network

    Wu, Ke-Li

    . As compared to a conventional circular wave- guide dual-mode (CWDM) filter, it provides more freedoms the effectiveness of full-wave EM modal analysis. Comparing to the best possible design of conventional CWDM filters waveguide dual-mode (CWDM) filter, amongst other filter technologies, has been the most preferred choice

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

    PubMed Central

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

    2011-01-01

    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

  14. A four step methodology for using simulation and optimization technologies in strategic supply chain planning

    Microsoft Academic Search

    D. A. Hicks

    1999-01-01

    Supply chains are real-world systems that transform raw materials and resources into end-products that are consumed by customers. Supply chains encompass a series of steps that add value through time, place and material transformation. Each manufacturer or distributor has some subset of the supply chain that it must manage and run profitably and efficiently to survive and grow. Decisions about

  15. Bounds on the performance of particle filters

    NASA Astrophysics Data System (ADS)

    Snyder, C.; Bengtsson, T.

    2014-12-01

    Particle filters rely on sequential importance sampling and it is well known that their performance can depend strongly on the choice of proposal distribution from which new ensemble members (particles) are drawn. The use of clever proposals has seen substantial recent interest in the geophysical literature, with schemes such as the implicit particle filter and the equivalent-weights particle filter. A persistent issue with all particle filters is degeneracy of the importance weights, where one or a few particles receive almost all the weight. Considering single-step filters such as the equivalent-weights or implicit particle filters (that is, those in which the particles and weights at time tk depend only on the observations at tk and the particles and weights at tk-1), two results provide a bound on their performance. First, the optimal proposal minimizes the variance of the importance weights not only over draws of the particles at tk, but also over draws from the joint proposal for tk-1 and tk. This shows that a particle filter using the optimal proposal will have minimal degeneracy relative to all other single-step filters. Second, the asymptotic results of Bengtsson et al. (2008) and Snyder et al. (2008) also hold rigorously for the optimal proposal in the case of linear, Gaussian systems. The number of particles necessary to avoid degeneracy must increase exponentially with the variance of the incremental importance weights. In the simplest examples, that variance is proportional to the dimension of the system, though in general it depends on other factors, including the characteristics of the observing network. A rough estimate indicates that single-step particle filter applied to global numerical weather prediction will require very large numbers of particles.

  16. A multiobjective interval programming model for wind-hydrothermal power system dispatching using 2-step optimization algorithm.

    PubMed

    Ren, Kun; Jihong, Qu

    2014-01-01

    Wind-hydrothermal power system dispatching has received intensive attention in recent years because it can help develop various reasonable plans to schedule the power generation efficiency. But future data such as wind power output and power load would not be accurately predicted and the nonlinear nature involved in the complex multiobjective scheduling model; therefore, to achieve accurate solution to such complex problem is a very difficult task. This paper presents an interval programming model with 2-step optimization algorithm to solve multiobjective dispatching. Initially, we represented the future data into interval numbers and simplified the object function to a linear programming problem to search the feasible and preliminary solutions to construct the Pareto set. Then the simulated annealing method was used to search the optimal solution of initial model. Thorough experimental results suggest that the proposed method performed reasonably well in terms of both operating efficiency and precision. PMID:24895663

  17. Constrained segment shapes in direct-aperture optimization for step-and-shoot IMRT

    SciTech Connect

    Bedford, James L.; Webb, Steve [Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Foundation Trust, Downs Road, Sutton, Surrey SM2 5PT (United Kingdom)

    2006-04-15

    Previous studies have shown that, by optimizing segment shapes and weights directly, without explicitly optimizing fluence profiles, effective IMRT plans can be generated with fewer segments. This study proposes a method of direct-aperture optimization with aperture shape constraints, which is designed to provide segmental IMRT plans using a minimum of simple, regular segments. The method uses a cubic function to create smoothly curving multileaf collimator shapes. Constraints on segment dimension and equivalent square are applied, and each segment can be constrained to lie within the previous one, for easy generation of fluence profiles with a single maximum. To simply optimize the segment shapes and reject any shapes which violate the constraints is too inefficient, so an innovative method of feedback optimization is used to ensure in advance that viable aperture shapes are generated. The algorithm is demonstrated using a simple cylindrical phantom consisting of a hemi-annular planning target volume and a central cylindrical organ-at-risk. A simple IMRT rectum case is presented, where segments are used to replace a wedge. More complex cases of prostate and seminal vesicles and prostate and pelvic nodes are also shown. The algorithm produces effective plans in each case with three to five segments per beam. For the simple plans, the constraint that each segment should be contained within the previous one adds additional simplicity to the plan, for a small reduction in plan quality. This study confirms that direct-aperture optimization gives efficient solutions to the segmental IMRT inverse problem and provides a method for generating simple apertures. By using such a method, the workload of IMRT verification may be reduced and simplified, as verification of fluence profiles from individual beams may be eliminated.

  18. An Interior-Point Algorithm for Large-Scale Nonlinear Optimization with Inexact Step Computations

    Microsoft Academic Search

    Frank E. Curtis; Olaf Schenk; Andreas Wächter

    2010-01-01

    ACHTERz Abstract. We present a line-search interior-point algorithm for large-scale continuous optimiza- tion. The algorithm is matrix-free in that it does not require the factorization of derivative matrices and instead uses iterative linear system solvers. Inexact step computations are supported in order to save computational expense during each iteration. The algorithm is an interior-point approach derived from the inexact Newton

  19. Metrics For Comparing Plasma Mass Filters

    SciTech Connect

    Abraham J. Fetterman and Nathaniel J. Fisch

    2012-08-15

    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. __________________________________________________

  20. Metrics for comparing plasma mass filters

    SciTech Connect

    Fetterman, Abraham J.; Fisch, Nathaniel J. [Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540 (United States)

    2011-10-15

    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.

  1. Non-convex optimization for the design of sparse FIR filters

    E-print Network

    Wei, Dennis

    This paper presents a method for designing sparse FIR filters by means of a sequence of p-norm minimization problems with p gradually decreasing from 1 toward 0. The lack of convexity for p < 1 is partially overcome by ...

  2. Two-step reconstruction method using global optimization and conjugate gradient for ultrasound-guided diffuse optical tomography

    NASA Astrophysics Data System (ADS)

    Tavakoli, Behnoosh; Zhu, Quing

    2013-01-01

    Ultrasound-guided diffuse optical tomography (DOT) is a promising method for characterizing malignant and benign lesions in the female breast. We introduce a new two-step algorithm for DOT inversion in which the optical parameters are estimated with the global optimization method, genetic algorithm. The estimation result is applied as an initial guess to the conjugate gradient (CG) optimization method to obtain the absorption and scattering distributions simultaneously. Simulations and phantom experiments have shown that the maximum absorption and reduced scattering coefficients are reconstructed with less than 10% and 25% errors, respectively. This is in contrast with the CG method alone, which generates about 20% error for the absorption coefficient and does not accurately recover the scattering distribution. A new measure of scattering contrast has been introduced to characterize benign and malignant breast lesions. The results of 16 clinical cases reconstructed with the two-step method demonstrates that, on average, the absorption coefficient and scattering contrast of malignant lesions are about 1.8 and 3.32 times higher than the benign cases, respectively.

  3. A Full-Newton Step O(n) Infeasible Interior-Point Algorithm for Linear Optimization

    Microsoft Academic Search

    C. Roos

    2006-01-01

    We present a primal-dual infeasible interior-point algorithm. As usual, the algorithm decreases the duality gap and the feasibility residuals at the same rate. Assuming that an optimal solution exists it is shown that at most O(n) iterations suffice to reduce the duality gap and the residuals by the factor 1\\/e. This implies an O(nlog(n\\/?)) iteration bound for getting an ?-solution

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

    SciTech Connect

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

    2006-01-01

    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.

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

    E-print Network

    Bondugula, Srikant

    2010-07-14

    progress and progress measurements. The controller is then formulated for iteratively calculating the optimal resource allocation schedule that minimizes either the EAC or both the EAC and EDAC together using the evolutionary optimization algorithm...

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

    Microsoft Academic Search

    Wang Yuzhe; Shi Xiaoping

    2010-01-01

    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

  7. A new technique for the design of two-dimensional FIR and IIR filters

    Microsoft Academic Search

    G. Lampropoulos; M. Fahmy

    1985-01-01

    The design problem of two-dimensional digital filters is the subject of this paper. The problem is formulated for both FIR and IIR filters in such a way that the performance index is a convex function of the optimization vector. The design technique is based on Newton's method. Each iteration consists of N easily computed steps, where N is the number

  8. Influence of simulation time-step (temporal-scale) on optimal parameter estimation and runoff prediction performance in hydrological modeling

    NASA Astrophysics Data System (ADS)

    Loizu, Javier; Álvarez-Mozos, Jesús; Casalí, Javier; Goñi, Mikel

    2015-04-01

    Nowadays, most hydrological catchment models are designed to allow their use for streamflow simulation at different time-scales. While this permits models to be applied for broader purposes, it can also be a source of error in hydrological processes simulation at catchment scale. Those errors seem not to affect significantly simple conceptual models, but this flexibility may lead to large behavior errors in physically based models. Equations used in processes such as those related to soil moisture time-variation are usually representative at certain time-scales but they may not characterize properly water transfer in soil layers at larger scales. This effect is especially relevant as we move from detailed hourly scale to daily time-step, which are common time scales used at catchment streamflow simulation for different research and management practices purposes. This study aims to provide an objective methodology to identify the degree of similarity of optimal parameter values when hydrological catchment model calibration is developed at different time-scales. Thus, providing information for an informed discussion of physical parameter significance on hydrological models. In this research, we analyze the influence of time scale simulation on: 1) the optimal values of six highly sensitive parameters of the TOPLATS model and 2) the streamflow simulation efficiency, while optimization is carried out at different time scales. TOPLATS (TOPMODEL-based Land-Atmosphere Transfer Scheme) has been applied on its lumped version on three catchments of varying size located in northern Spain. The model has its basis on shallow groundwater gradients (related to local topography) that set up spatial patterns of soil moisture and are assumed to control infiltration and runoff during storm events and evaporation and drainage in between storm events. The model calculates the saturated portion of the catchment at each time step based on Topographical Index (TI) intervals. Surface runoff is then calculated at rainfall events proportionally to the saturation degree of the catchment. Separately, baseflow is calculated based on the distance between catchment average water table depth and specific depth at each TI interval. This study focuses on the comparison of hourly and daily simulations for the 2000-2007 time period. An optimization algorithm has been applied to identify the optimal values of the following four soil properties: 1) Brooks-Corey pore size distribution index (?), 2) Bubbling pressure (?c), 3) Saturated soil moisture (?s), 4) Surface saturated hydraulic conductivity (Ks), and two subsurface flow controlling parameters: 1) Subsurface flow at complete saturation (Q0), and 2) Exponential coefficient for TOPMODEL baseflow equation (f). The algorithm was set up to maximize Nash-Sutcliffe Efficiency (NSE) at the catchment outlet. Results presented include the optimal values of each parameter at both hourly and daily time scale. These values provided valuable information to discuss the relative importance of each soil-related model parameter for enhanced streamflow simulation and adequate model response to both surface runoff and baseflow simulation. Catchment baseflow magnitude (Q0) and decay behavior (f) are also proved to require detailed analysis depending on the selected hydrological modeling purpose and corresponding selected time-step. Obtained results showed that different time-scale simulations may require different parameter values for soil properties and catchment behavior characterization in order to properly simulate streamflow at catchment scale. Despite calibrated parameters were soil properties and water flow quantities with physical meaning and defined units, optimum values differed with time-scale and were not always similar to field observations.

  9. Optimized FPGA Implementation of Multi-Rate FIR Filters Through Thread Decomposition

    NASA Technical Reports Server (NTRS)

    Kobayashi, Kayla N.; He, Yutao; Zheng, Jason X.

    2011-01-01

    Multi-rate finite impulse response (MRFIR) filters are among the essential signal-processing components in spaceborne instruments where finite impulse response filters are often used to minimize nonlinear group delay and finite precision effects. Cascaded (multistage) designs of MRFIR filters are further used for large rate change ratio in order to lower the required throughput, while simultaneously achieving comparable or better performance than single-stage designs. Traditional representation and implementation of MRFIR employ polyphase decomposition of the original filter structure, whose main purpose is to compute only the needed output at the lowest possible sampling rate. In this innovation, an alternative representation and implementation technique called TD-MRFIR (Thread Decomposition MRFIR) is presented. The basic idea is to decompose MRFIR into output computational threads, in contrast to a structural decomposition of the original filter as done in the polyphase decomposition. A naive implementation of a decimation filter consisting of a full FIR followed by a downsampling stage is very inefficient, as most of the computations performed by the FIR state are discarded through downsampling. In fact, only 1/M of the total computations are useful (M being the decimation factor). Polyphase decomposition provides an alternative view of decimation filters, where the downsampling occurs before the FIR stage, and the outputs are viewed as the sum of M sub-filters with length of N/M taps. Although this approach leads to more efficient filter designs, in general the implementation is not straightforward if the numbers of multipliers need to be minimized. In TD-MRFIR, each thread represents an instance of the finite convolution required to produce a single output of the MRFIR. The filter is thus viewed as a finite collection of concurrent threads. Each of the threads completes when a convolution result (filter output value) is computed, and activated when the first input of the convolution becomes available. Thus, the new threads get spawned at exactly the rate of N/M, where N is the total number of taps, and M is the decimation factor. Existing threads retire at the same rate of N/M. The implementation of an MRFIR is thus transformed into a problem to statically schedule the minimum number of multipliers such that all threads can be completed on time. Solving the static scheduling problem is rather straightforward if one examines the Thread Decomposition Diagram, which is a table-like diagram that has rows representing computation threads and columns representing time. The control logic of the MRFIR can be implemented using simple counters. Instead of decomposing MRFIRs into subfilters as suggested by polyphase decomposition, the thread decomposition diagrams transform the problem into a familiar one of static scheduling, which can be easily solved as the input rate is constant.

  10. OVERSAMPLED FILTER BANKS: OPTIMAL NOISlE SHAPING, DESIGN FREEDOM, AND NOISE ANALY!SIS

    Microsoft Academic Search

    Helmut Bolcskei; Franz Hlawatsch

    We show that oversampled filter banks FBs) of- fer more design freedom and less noise sensitivity t 6 an crit- ically sampled FBs. We provide a parameterization of all synthesis FBs satisfyin perfect reconstruction for a given oversampled analysis FE, and we derive bounds and expres- sions for the variance of the reconstruction error due to noisy subband signals. Finally,

  11. Improved design and optimization of subsurface flow constructed wetlands and sand filters

    Microsoft Academic Search

    A. Brovelli; O. Carranza-Díaz; L. Rossi; D. A. Barry

    2010-01-01

    Subsurface flow constructed wetlands and sand filters are engineered systems capable of eliminating a wide range of pollutants from wastewater. These devices are easy to operate, flexible and have low maintenance costs. For these reasons, they are particularly suitable for small settlements and isolated farms and their use has substantially increased in the last 15 years. Furthermore, they are also

  12. Optimal steering vector adaptation for linear filters leading to robust beamforming

    E-print Network

    Wichmann, Felix

    . INTRODUCTION AND PROBLEM STATEMENT IN many applications it is necessary to detect a specific signal within in the form f = H ¯p ¯pH ¯p , (2) and a signal is detected when the filter output exceeds a certain threshold approaches, the algorithm works on sparse signals with arbitrary steering vector shapes, and the parameters

  13. Bacterial Foraging Technique-Based Optimized Active Power Filter for Load Compensation

    Microsoft Academic Search

    S. Mishra; C. N. Bhende

    2007-01-01

    The conventional method of obtaining the coefficients of proportional plus integral (PI) controllers for the active power filter utilizes a linear model of the PWM inverter. The values so obtained may not give satisfactory results for a wide variation in operating conditions. This paper presents a new algorithm based on the foraging behavior of E-coli Bacteria in the human intestine,

  14. Optimal Attitude Estimation and Filtering Without Using Local Coordinates Part I: Uncontrolled and Deterministic Attitude Dynamics

    Microsoft Academic Search

    Amit K. Sanyal

    2006-01-01

    Most existing algorithms for attitude estimation of mechanical systems use generalized coordinates to represent the group of rigid body rotations. Generalized coordinate representations of the group of rotations have some associated problems. While minimal (focal) coordinate representations exhibit kinematic singularities for large rotations, the quaternion representation requires satisfaction of an extra constraint. This paper treats the attitude estimation and filtering

  15. Optimized design of an electrochemical filter-press reactor using CFD methods

    Microsoft Academic Search

    Ángel Frías-Ferrer; Ignacio Tudela; Olivier Louisnard; Verónica Sáez; María Deseada Esclapez; María Isabel Díez-García; Pedro Bonete; José González-García

    2011-01-01

    A former laboratory filter-press electrochemical reactor previously used in electrodialysis, electrosynthesis and wastewater treatment was studied from a hydrodynamic point of view using computational fluid dynamics (CFD). A finite elements method (FEM) software environment was used in order to simulate both fluid velocity field and tracer diffusion in the reactor for different low Reynolds numbers, enabling the estimation of active

  16. A New Color Filter Array With Optimal Properties for Noiseless and Noisy Color Image Acquisition

    Microsoft Academic Search

    Laurent Condat

    2011-01-01

    Digital color cameras acquire color images by means of a sensor on which a color filter array (CFA) is overlaid. The Bayer CFAdominates the consumer market, but there has recently been a renewed interest for the design of CFAs (2)-(6). However, robustness to noise is often neglected in the design, though it is crucial in practice. In this paper, we

  17. Optimization and Application of Median Filter Corrections to Relieve Diverse Spatial Patterns in Microtiter Plate Data

    PubMed Central

    Bushway, Paul J.; Azimi, Behrad; Heynen-Genel, Susanne

    2014-01-01

    The standard (STD) 5 × 5 hybrid median filter (HMF) was previously described as a nonparametric local backestimator of spatially arrayed microtiter plate (MTP) data. As such, the HMF is a useful tool for mitigating global and sporadic systematic error in MTP data arrays. Presented here is the first known HMF correction of a primary screen suffering from systematic error best described as gradient vectors. Application of the STD 5 × 5 HMF to the primary screen raw data reduced background signal deviation, thereby improving the assay dynamic range and hit confirmation rate. While this HMF can correct gradient vectors, it does not properly correct periodic patterns that may present in other screening campaigns. To address this issue, 1 × 7 median and a row/column 5 × 5 hybrid median filter kernels (1 × 7 MF and RC 5 × 5 HMF) were designed ad hoc, to better fit periodic error patterns. The correction data show periodic error in simulated MTP data arrays is reduced by these alternative filter designs and that multiple corrective filters can be combined in serial operations for progressive reduction of complex error patterns in a MTP data array. PMID:21900202

  18. Gain optimization of one-pump fiber-optical parametric amplifier with optical band-pass filter reducing the idler wave

    NASA Astrophysics Data System (ADS)

    Zhu, Hongna; Luo, Bin; Wang, Li; Pan, Wei; Yan, Lianshan; Zhao, Jianpeng; Gao, Xiaorong; Wang, Zeyong

    2012-09-01

    The gain optimization characteristics of a one-pump fiber-optical parametric amplifier with an optical band-pass filter (OBPF) reducing the idler wave is investigated numerically. The phase mismatching is compensated, thus both the maximum gain and the gain bandwidth are optimized with the OBPF inserted in, and the flatter gain can be obtained; meanwhile, the conversion efficiency of the pump power to the signal power is increased. The influence of filter attenuation on the gain is also discussed. It is shown that, by properly selecting the parameters of the fiber, signal wave, pump wave, and filter, the optimized gain can be obtained, which is extremely useful for the optical communication systems.

  19. Optimized, one-step, recovery-enrichment broth for enhanced detection of Listeria monocytogenes in pasteurized milk and hot dogs.

    PubMed

    Knabel, Stephen J

    2002-01-01

    A one-step, recovery-enrichment broth, optimized Penn State University (oPSU) broth, was developed to consistently detect low levels of injured and uninjured Listeria monocytogenes cells in ready-to-eat foods. The oPSU broth contains special selective agents that inhibit growth of background flora without inhibiting recovery of injured Listeria cells. After recovery in the anaerobic section of oPSU broth, Listeria cells migrated to the surface, forming a black zone. This migration separated viable from nonviable cells and the food matrix, thereby reducing inhibitors that prevent detection by molecular methods. The high Listeria-to-background ratio in the black zone resulted in consistent detection of low levels of L. monocytogenes in pasteurized foods by both cultural and molecular methods, and greatly reduced both false-negative and false-positive results. oPSU broth does not require transfer to a secondary enrichment broth, making it less laborious and less subject to external contamination than 2-step enrichment protocols. Addition of 150mM D-serine prevented germination of Bacillus spores, but not the growth of vegetative cells. Replacement of D-serine with 12 mg/L acriflavin inhibited growth of vegetative cells of Bacillus spp. without inhibiting recovery of injured Listeria cells. oPSU broth may allow consistent detection of low levels of injured and uninjured cells of L. monocytogenes in pasteurized foods containing various background microflora. PMID:11990038

  20. TIPS AND STEP-BY-STEP PROTOCOL FOR THE OPTIMIZATION OF IMPORTANT FACTORS AFFECTING CELLULAR ENZYME-LINKED IMMUNOSORBENT ASSAY (CELISA)

    Microsoft Academic Search

    R. Morandini; J.-M. Boeynaems; J. Wérenne; G. Ghanem

    2001-01-01

    CELISA, or cellular enzyme-linked immunosorbent assay, is a powerful and easy to use technique to study cell surface antigens under different stimulations. Nevertheless, some factors [11] must be discussed and optimized prior to reaching a reproducible CELISA. These include the choice of cell density, fixative agent, blocking agent, culture medium, optimal antibody dilutions, and incubation time. In this paper, we

  1. Design of FIR digital filters for pulse shaping and channel equalization using time-domain optimization

    NASA Technical Reports Server (NTRS)

    Houts, R. C.; Vaughn, G. L.

    1974-01-01

    Three algorithms are developed for designing finite impulse response digital filters to be used for pulse shaping and channel equalization. The first is the Minimax algorithm which uses linear programming to design a frequency-sampling filter with a pulse shape that approximates the specification in a minimax sense. Design examples are included which accurately approximate a specified impulse response with a maximum error of 0.03 using only six resonators. The second algorithm is an extension of the Minimax algorithm to design preset equalizers for channels with known impulse responses. Both transversal and frequency-sampling equalizer structures are designed to produce a minimax approximation of a specified channel output waveform. Examples of these designs are compared as to the accuracy of the approximation, the resultant intersymbol interference (ISI), and the required transmitted energy. While the transversal designs are slightly more accurate, the frequency-sampling designs using six resonators have smaller ISI and energy values.

  2. An optimal circular-waveguide dual-mode filter without tuning screws

    Microsoft Academic Search

    Ke-Li Wu

    1999-01-01

    A novel circular-waveguide dual-mode (CWDM) filter structure is proposed. The coupling between the degenerate modes in the same cavity is provided by an off-centered circular iris built in at the middle of the resonant cavities. Considering the facts of: (1) simplicity of the mechanical process; (2) a potentially high Q; (3) a wide spurious-free frequency band; and (4) the effectiveness

  3. IMC Design Based Optimal Tuning of a PID-Filter Governor Controller for Hydro Power Plant

    Microsoft Academic Search

    Anil Naik Kanasottu; Srikanth Pullabhatla; Venkata Reddy Mettu

    \\u000a In the present paper a PID-Filter governor controller with Internal Model Control (IMC) tuning method for the hydro electric\\u000a power plant is presented. The IMC has a single tuning parameter to adjust the performance and robustness of the controller.\\u000a The proposed tuning method is very efficient in controlling the overshoot, stability and the dynamics of the speed-governing\\u000a system of the

  4. Microstrip bandpass filters for Ultra-Wideband (UWB) wireless communications

    Microsoft Academic Search

    Ching-Luh Hsu; Fu-Chieh Hsu; Jen-Tsai Kuo

    2005-01-01

    A new technique is developed for designing a composite microstrip bandpass filter (BPF) with a 3 dB fractional bandwidth of more than 100%. The BPF is suitable for ultra-wideband (UWB) wireless communications. The design utilizes embedding individually designed highpass structures and lowpass filters (LPF) into each other, followed by an optimization for tuning in-band performance. The stepped-impedance LPF is employed

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

    E-print Network

    Bondugula, Srikant

    2010-07-14

    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...

  6. Topology optimization of dielectric substrates for filters and antennas using SIMP

    Microsoft Academic Search

    G. Kiziltas; N. Kikuchi; J. L. Volakis; J. Halloran

    2004-01-01

    Summary  In this paper a novel design procedure based on the integration of full wave Finite Element Analysis (FEA) and a topology\\u000a design method employing Sequential Linear Programming (SLP) is introduced. The employed design method is the Solid Isotropic\\u000a Material with Penalization (SIMP) technique formulated as a general non-linear optimization problem. SLP is used to solve\\u000a the optimization problem with the

  7. 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)

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

    2007-03-01

    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.

  8. Long-range high spatial resolution optical frequency-domain reflectometry based on optimized deskew filter method

    NASA Astrophysics Data System (ADS)

    Ding, Zhenyang; Du, Yang; Liu, Tiegen; Yao, X. Steve; Feng, Bowen; Liu, Kun; Jiang, Junfeng

    2014-11-01

    We present a long-range high spatial resolution optical frequency-domain reflectometry (OFDR) based on optimized deskew filter method. In proposed method, the frequency tuning nonlinear phase obtained from an auxiliary interferometer is used to compensate the nonlinear phase of the beating signals generated from a main OFDR interferometer using a deskew filter. The method can be applied for the entire spatial domain of the OFDR signals at once with a high computational efficiency. In addition, we apply the methods of higher orders of Taylor expansion and cepstrum analysis to improve the estimation accuracy of nonlinear phase. We experimentally achieve a measurement range of 80 km and a spatial resolution of 20 cm and 80 cm at distances of 10 km and 80 km that is about 187 times enhancement when compared with that of the same OFDR trace without nonlinearity compensation. The improved performance of the OFDR with the high spatial resolution, long measurement range and short process time will lead to practical applications in real-time monitoring and measurement of the optical fiber communication and sensing systems.

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    Two matched filter theory based schemes are described and illustrated for obtaining maximized and time correlated gust loads for a nonlinear aircraft. The first scheme is computationally fast because it uses a simple 1-D search procedure to obtain its answers. The second scheme is computationally slow because it uses a more complex multi-dimensional 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.

  11. Analog FIR Filter Used for Range-Optimal Pulsed Radar Applications

    E-print Network

    Su, Eric Chen

    2014-08-13

    friends in AMSC, in particular, Barry, Yanjie Sun, Congyin Shi, Jun Yan, Qiyuan Liu, Cheng-Ming Chien Mengde Wang and Han Chen for the happy times we shared Finally, thanks to my parents and my sister. Mere words cannot express my gratitude... OTA was reviewed and proposed, after some analysis we chose one that was suitable, and implemented it on chip to meet the required specification for the system. The main challenge in designing the filter for this application is to design a reliable...

  12. PEEC-Models for EMC filter layout optimization Thomas De Oliveira, Jean-Michel Guichon, Jean-Luc Schanen, Laurent Gerbaud

    E-print Network

    Paris-Sud XI, Université de

    the optimal component placement and the associated track design, in order to improve the filter transfer, and has to be com- pleted with a series capacitance. The magnetic behaviour of this equivalent components) and of the ca- pacitor and the associated magnetic couplings with the surrounding environment (other components

  13. Optimization of Rugate filters for ultra light-trapping in solar cells

    Microsoft Academic Search

    Stephan Fahr; Carolin Ulbrich; Thomas Kirchartz; Uwe Rau; Carsten Rockstuhl; Falk Lederer

    2008-01-01

    We present the optimization of coatings that can be applied on top of solar cells. The purpose of these coatings is to reduce the light acceptance cone only in the long wavelength range. This allows for high transmission of light into the solar cell independent on the angle of incidence in the short wavelength range where the solar cell material

  14. Estimation of the error for small-sample optimal binary filter design using prior knowledge 

    E-print Network

    Sabbagh, David L

    1999-01-01

    knowledge about this distribution. This thesis gives an analytic expression of this majoring under some assumptions and shows that, using such a method, we derive a very good estimate of tile optimal error, even for a very limited amount of data....

  15. Calculating the optimal hedge ratio: constant, time varying and the Kalman Filter approach

    Microsoft Academic Search

    Abdulnasser Hatemi-Ja; Eduardo Roca

    2006-01-01

    A crucial input in the hedging of risk is the optimal hedge ratio – defined by the relationship between the price of the spot instrument and that of the hedging instrument. Since it has been shown that the expected relationship between economic or financial variables may be better captured by a time varying parameter model rather than a fixed coefficient

  16. Sparse gammatone signal model optimized for English speech does not match the human auditory filters

    Microsoft Academic Search

    Stefan Strahl; Alfred Mertins

    2008-01-01

    Evidence that neurosensory systems use sparse signal representations as well as improved performance of signal processing algorithms using sparse signal models raised interest in sparse signal coding in the last years. For natural audio signals like speech and environmental sounds, gammatone atoms have been derived as expansion functions that generate a nearly optimal sparse signal model (Smith, E., Lewicki, M.,

  17. JOINT OPTIMIZATION OF MULTIPLE BEHAVIORAL AND IMPLEMENTATION PROPERTIES OF DIGITAL IIR FILTER DESIGNS

    E-print Network

    Evans, Brian L.

    processing. A conventional method to linearize the phase is to cascade allpass lters. This structure not be realizable This work was supported by US Defense Advanced Research Projects Agency Grant DAAB07-97-C-J007 is an extension of our multicriteria analog IIR lter optimization framework 4 . We model the constrained nonlinear

  18. [A new impulse noise filter based on pulse coupled neural network].

    PubMed

    Ma, Yide; Shi, Fei; Li, Lian; An, Lizhe

    2004-12-01

    This paper presents a new impulse noise filter based on pulse coupled neural networks according to the apparent difference of gray value between noised pixels and the pixels around them. Comparing with the state-of-the-art denoised PCNN filter, the step by step modifying algorithm based on PCNN also, the new PCNN filter suggested in this paper costs less computation and less execution time. At the same time this new PCNN filter has been compared with other nonlinear filters, such as median filter, the stack filter based on omnidirectional structural elements constrains, the Omnidirectional morphology Open-Closing maximum filter (OOCmax) and the Omnidirectional morphology Close-Opening minimum (OCOmin) filter. The results of simulation shows that this algorithm is superior to standard median filter, the state-of-the-art PCNN filter, the maximal, minimal morphological filter with omnidirectional structuring elements, and the optimal stack filter based on omnidirectional structural elements constrains in the aspect of the impulse noise removal. What is more important is that this algorithm can keep the details of images more effectively. PMID:15646356

  19. Optimized selective lactate excitation with a refocused multiple-quantum filter

    NASA Astrophysics Data System (ADS)

    Holbach, Mirjam; Lambert, Jörg; Johst, Sören; Ladd, Mark E.; Suter, Dieter

    2015-06-01

    Selective detection of lactate signals in in vivo MR spectroscopy with spectral editing techniques is necessary in situations where strong lipid or signals from other molecules overlap the desired lactate resonance in the spectrum. Several pulse sequences have been proposed for this task. The double-quantum filter SSel-MQC provides very good lipid and water signal suppression in a single scan. As a major drawback, it suffers from significant signal loss due to incomplete refocussing in situations where long evolution periods are required. Here we present a refocused version of the SSel-MQC technique that uses only one additional refocussing pulse and regains the full refocused lactate signal at the end of the sequence.

  20. Optimized selective lactate excitation with a refocused multiple-quantum filter.

    PubMed

    Holbach, Mirjam; Lambert, Jörg; Johst, Sören; Ladd, Mark E; Suter, Dieter

    2015-06-01

    Selective detection of lactate signals in in vivo MR spectroscopy with spectral editing techniques is necessary in situations where strong lipid or signals from other molecules overlap the desired lactate resonance in the spectrum. Several pulse sequences have been proposed for this task. The double-quantum filter SSel-MQC provides very good lipid and water signal suppression in a single scan. As a major drawback, it suffers from significant signal loss due to incomplete refocussing in situations where long evolution periods are required. Here we present a refocused version of the SSel-MQC technique that uses only one additional refocussing pulse and regains the full refocused lactate signal at the end of the sequence. PMID:25909643

  1. Many-objective Groundwater Monitoring Network Design Using Bias-Aware Ensemble Kalman Filtering, Evolutionary Optimization, and Visual Analytics

    NASA Astrophysics Data System (ADS)

    Kollat, J. B.; Reed, P. M.; Maxwell, R. M.

    2010-12-01

    This study contributes the ASSIST (Adaptive Strategies for Sampling in Space and Time) framework for improving long-term groundwater monitoring decisions across space and time while accounting for the influences of systematic model errors (or predictive bias). The new framework combines contaminant flow-and-transport modeling, bias-aware ensemble Kalman filtering (EnKF), many-objective evolutionary optimization, and visual analytics-based decision support. The ASSIST framework allows decision makers to forecast the value of investments in new observations for many objectives simultaneously. Information tradeoffs are evaluated using an EnKF to forecast plume transport in space and time in the presence of uncertain and biased model predictions that are conditioned on uncertain measurement data. This study demonstrates the ASSIST framework using a laboratory-based physical aquifer tracer experiment. In this initial demonstration, the position and frequency of tracer sampling was optimized to: (1) minimize monitoring costs, (2) maximize the information provided to the EnKF, (3) minimize failures to detect the tracer, (4) maximize the detection of tracer fluxes, (5) minimize error in quantifying tracer mass, and (6) minimize error in quantifying the centroid of the tracer plume. Our results demonstrate that the forecasting, search, and visualization components of the ASSIST framework represent a significant advance for observation network design that has a strong potential to innovate our characterization, prediction, and management of groundwater systems.

  2. Many-objective groundwater monitoring network design using bias-aware ensemble Kalman filtering, evolutionary optimization, and visual analytics

    NASA Astrophysics Data System (ADS)

    Kollat, J. B.; Reed, P. M.; Maxwell, R. M.

    2011-02-01

    This study contributes the Adaptive Strategies for Sampling in Space and Time (ASSIST) framework for improving long-term groundwater monitoring decisions across space and time while accounting for the influences of systematic model errors (or predictive bias). The new framework combines contaminant flow-and-transport modeling, bias-aware ensemble Kalman filtering (EnKF), many-objective evolutionary optimization, and visual analytics-based decision support. The ASSIST framework allows decision makers to forecast the value of investments in new observations for many objectives simultaneously. Information tradeoffs are evaluated using an EnKF to forecast plume transport in space and time in the presence of uncertain and biased model predictions that are conditioned on uncertain measurement data. This study demonstrates the ASSIST framework using a laboratory-based physical aquifer tracer experiment. In this initial demonstration, the position and frequency of tracer sampling was optimized to (1) minimize monitoring costs, (2) maximize the information provided to the EnKF, (3) minimize failures to detect the tracer, (4) maximize the detection of tracer fluxes, (5) minimize error in quantifying tracer mass, and (6) minimize error in quantifying the centroid of the tracer plume. Our results demonstrate that the forecasting, search, and visualization components of the ASSIST framework represent a significant advance for observation network design that has a strong potential to innovate our characterization, prediction, and management of groundwater systems.

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

    Microsoft Academic Search

    Lei Zhang; Tadeusz Kwasniewski

    2009-01-01

    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

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

    NASA Technical Reports Server (NTRS)

    1974-01-01

    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.

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

    E-print Network

    Paris-Sud XI, Université de

    ), a constant voltage on the DC side of the inverter was proposed, it is a photovoltaic generator which is used voltage Voptimal(t) Optimal voltage Vdc Dc voltage Vs1, Vs2, Vs3 Three phase Source voltage P, q active and reactive Power Ic1, Ic2, Ic3 Load currents 1I , 2I , 3I Source currents sV , sV Alpha-Beta voltage

  6. Auditory filter bank inversion

    Microsoft Academic Search

    L. Lin; W. H. Holines; Eliathamby Ambikairajah

    2001-01-01

    Models of auditory filtering using the Gammatone filter bank are useful tools in speech processing. A perceptually accurate auditory inversion model has applications in speech and audio coding. This paper proposes a new auditory filter bank inversion method using a least squares optimization technique. The proposed method is computationally efficient and its low delay makes it suitable for frame-by-frame processing.

  7. Nonlinear Attitude Filtering Methods

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

    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.

  8. Optimal filtering and Bayesian detection for friction-based diagnostics in machines.

    PubMed

    Ray, L R; Townsend, J R; Ramasubramanian, A

    2001-01-01

    Non-model-based diagnostic methods typically rely on measured signals that must be empirically related to process behavior or incipient faults. The difficulty in interpreting a signal that is indirectly related to the fundamental process behavior is significant. This paper presents an integrated non-model and model-based approach to detecting when process behavior varies from a proposed model. The method, which is based on nonlinear filtering combined with maximum likelihood hypothesis testing, is applicable to dynamic systems whose constitutive model is well known, and whose process inputs are poorly known. Here, the method is applied to friction estimation and diagnosis during motion control in a rotating machine. A nonlinear observer estimates friction torque in a machine from shaft angular position measurements and the known input voltage to the motor. The resulting friction torque estimate can be analyzed directly for statistical abnormalities, or it can be directly compared to friction torque outputs of an applicable friction process model in order to diagnose faults or model variations. Nonlinear estimation of friction torque provides a variable on which to apply diagnostic methods that is directly related to model variations or faults. The method is evaluated experimentally by its ability to detect normal load variations in a closed-loop controlled motor driven inertia with bearing friction and an artificially-induced external line contact. Results show an ability to detect statistically significant changes in friction characteristics induced by normal load variations over a wide range of underlying friction behaviors. PMID:11515939

  9. Technical note: Optimization for improved tube-loading efficiency in the dual-energy computed tomography coupled with balanced filter method

    SciTech Connect

    Saito, Masatoshi [Department of Radiological Technology, School of Health Sciences, Faculty of Medicine, Niigata University, Niigata 951-8518 (Japan)

    2010-08-15

    Purpose: This article describes the spectral optimization of dual-energy computed tomography using balanced filters (bf-DECT) to reduce the tube loadings and dose by dedicating to the acquisition of electron density information, which is essential for treatment planning in radiotherapy. Methods: For the spectral optimization of bf-DECT, the author calculated the beam-hardening error and air kerma required to achieve a desired noise level in an electron density image of a 50-cm-diameter cylindrical water phantom. The calculation enables the selection of beam parameters such as tube voltage, balanced filter material, and its thickness. Results: The optimal combination of tube voltages was 80 kV/140 kV in conjunction with Tb/Hf and Bi/Mo filter pairs; this combination agrees with that obtained in a previous study [M. Saito, ''Spectral optimization for measuring electron density by the dual-energy computed tomography coupled with balanced filter method,'' Med. Phys. 36, 3631-3642 (2009)], although the thicknesses of the filters that yielded a minimum tube output were slightly different from those obtained in the previous study. The resultant tube loading of a low-energy scan of the present bf-DECT significantly decreased from 57.5 to 4.5 times that of a high-energy scan for conventional DECT. Furthermore, the air kerma of bf-DECT could be reduced to less than that of conventional DECT, while obtaining the same figure of merit for the measurement of electron density and effective atomic number. Conclusions: The tube-loading and dose efficiencies of bf-DECT were considerably improved by sacrificing the quality of the noise level in the images of effective atomic number.

  10. Development of optimized filter for TARC and developer with the goal of having small pore size and minimizing microbubble reduction

    NASA Astrophysics Data System (ADS)

    Umeda, Toru; Tsuzuki, Shuichi; Boucher, Mikal; Dinh, Hung; Ma, L. C.; Boten, Russell

    2006-03-01

    Microbubble in filtering Tetra Methyl Ammonium Hydroxide (TMAH) were counted to find the filter which generates the lowest microbubble in resist development process. Hydrophilic Highly Asymmetric Poly Aryl Sulfone (HAPAS) filter was developed and tested. The result showed that generation of microbubbles was as low as that of the Nylon 6,6 filter which had the best performance to date. Microbubbles in TARC are counted using the same method as the developer testing described above except for mainstream flow rate and the counter model. The results show that counts in the small channel could be reduced by smaller pore size filter such as conventional 0.02um rated filter. However, counts in the larger channel could be reduced by larger pore size filter such as 0.1um rated filter. Based on the above results, 0.02um rated asymmetric nylon 6,6 filter was developed. As a result, 0.02um rated asymmetric Nylon 6,6 filter achieved relatively lower count at any channel as compared to the standard 0.04um rated Nylon 6,6 filter. Nylon 6,6 filters were installed in resist as an improvement for preventive maintenance (PM) at Wafertech, L.L.C. instead of the currently used filter which has more hydrophobic membrane material. Using the Nylon 6,6 membrane, the number of defects immediately after filter change greatly decreased from 493 pcs of the more hydrophobic filter to 6 pcs/wafer, then after purging with about 250ml, the number of defects reduced within the process specification while the more hydrophobic filter had required 2L purging and 12-36 hours of PM time.

  11. Design and properties of integrated millimeter-wave bandpass filters using nonradiative dielectric waveguide for broadband wireless system

    NASA Astrophysics Data System (ADS)

    Boone, Francois; Hindson, Dan; Caron, Mario; Abdulnour, Jawad; Wu, Ke

    1999-12-01

    Conventional band-pass filter design is reviewed with respect to (non-radiative dielectric) NRD-guide technology and a new step-by-step method is proposed for the design of dual-path band-pass filter using small NRD guide resonator. A mode matching formulation, accounting for inherent higher- order modal coupling effects, is used to calculate the generalized S matrix of discontinuities encountered in all kind of filters, as well as to simulate the entire filters. Upon a reduction of the transfer function of the dual-path band-pass filter, a low-pass prototype network is obtained and calculated. Based on our mode-matching software tool, an iterative optimization process is then developed to design a filter with deep attenuation poles. A practical example is given and a short comparison with the conventional band-pass filter is made.

  12. Optimism

    PubMed Central

    Carver, Charles S.; Scheier, Michael F.; Segerstrom, Suzanne C.

    2010-01-01

    Optimism is an individual difference variable that reflects the extent to which people hold generalized favorable expectancies for their future. Higher levels of optimism have been related prospectively to better subjective well-being in times of adversity or difficulty (i.e., controlling for previous well-being). Consistent with such findings, optimism has been linked to higher levels of engagement coping and lower levels of avoidance, or disengagement, coping. There is evidence that optimism is associated with taking proactive steps to protect one's health, whereas pessimism is associated with health-damaging behaviors. Consistent with such findings, optimism is also related to indicators of better physical health. The energetic, task-focused approach that optimists take to goals also relates to benefits in the socioeconomic world. Some evidence suggests that optimism relates to more persistence in educational efforts and to higher later income. Optimists also appear to fare better than pessimists in relationships. Although there are instances in which optimism fails to convey an advantage, and instances in which it may convey a disadvantage, those instances are relatively rare. In sum, the behavioral patterns of optimists appear to provide models of living for others to learn from. PMID:20170998

  13. An Optimal Method For Wake Detection In SAR Images Using Radon Transformation Combined With Wavelet Filters

    E-print Network

    Krishnaveni, M; Subashini, P

    2009-01-01

    A new fangled method for ship wake detection in synthetic aperture radar (SAR) images is explored here. Most of the detection procedure applies the Radon transform as its properties outfit more than any other transformation for the detection purpose. But still it holds problems when the transform is applied to an image with a high level of noise. Here this paper articulates the combination between the radon transformation and the shrinkage methods which increase the mode of wake detection process. The latter shrinkage method with RT maximize the signal to noise ratio hence it leads to most optimal detection of lines in the SAR images. The originality mainly works on the denoising segment of the proposed algorithm. Experimental work outs are carried over both in simulated and real SAR images. The detection process is more adequate with the proposed method and improves better than the conventional methods.

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

    NASA Astrophysics Data System (ADS)

    Holbach, Mirjam; Lambert, Jörg; Suter, Dieter

    2014-06-01

    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.

  15. Scale-down models to optimize a filter train for the downstream purification of recombinant pharmaceutical proteins produced in tobacco leaves.

    PubMed

    Buyel, Johannes F; Fischer, Rainer

    2014-03-01

    The extraction of biopharmaceutical proteins from intact leaves involves the release of abundant particulate contaminants that must be removed economically from the process stream before chromatography, for example, using disposable filters that comply with good manufacturing practice. We therefore scaled down an existing 200-kg process for the purification of two target proteins from tobacco leaves (the monoclonal antibody 2G12 and the fluorescent protein DsRed, as monitored by surface plasmon resonance spectroscopy and fluorescence imaging, respectively) and screened different materials on the 2-kg scale to reduce the number of depth filtration steps from three to one. We assessed filter cost and capacity, filtrate turbidity, and protein recovery when the filter materials were challenged with extracts from different tobacco varieties and related species grown in soil or rockwool. PDF4 was consistently the most suitable depth filter because it was the least expensive, it did not interact significantly with the target proteins, and it had the greatest overall capacity. The filter capacity was generally reduced when plants were grown in rockwool, but this substrate has a low bioburden, thus improving process safety. Our data concerning the clarification of plant extracts will help in the design of more cost-effective downstream processes and accelerate their development. PMID:24323869

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

    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.

  17. Surface micromachined optical low-cost all-air-gap filters based on stress-optimized Si3N4 layers

    Microsoft Academic Search

    S. Irmer; K. Alex; J. Daleiden; I. Kommallein; M. Oliveira; F. Römer; A. Tarraf; H. Hillmer

    2005-01-01

    A new surface micromachining approach based on a multiple Si3N4- and silicon-layer stack is presented. The fabrication process is implemented by plasma-enhanced chemical vapour deposition of stress-optimized films, reactive ion etching using SF6\\/CHF3\\/Ar, wet chemical etching of the sacrificial silicon layers by KOH and critical point drying. Using this approach, the fabrication of an optical all-air-gap vertical-cavity Fabry-Pérot filter is

  18. Surface micromachined optical low-cost all-air-gap filters based on stress-optimized Si3N4 layers

    NASA Astrophysics Data System (ADS)

    Irmer, S.; Alex, K.; Daleiden, J.; Kommallein, I.; Oliveira, M.; Römer, F.; Tarraf, A.; Hillmer, H.

    2005-04-01

    A new surface micromachining approach based on a multiple Si3N4- and silicon-layer stack is presented. The fabrication process is implemented by plasma-enhanced chemical vapour deposition of stress-optimized films, reactive ion etching using SF6/CHF3/Ar, wet chemical etching of the sacrificial silicon layers by KOH and critical point drying. Using this approach, the fabrication of an optical all-air-gap vertical-cavity Fabry-Pérot filter is demonstrated. The surface micromachined filter consists of two DBR mirrors, each having five 590 nm thick Si3N4 membranes separated by 390 nm wide air gaps. The distance between the mirrors (cavity) is 710 nm. The optical characterization and a white light interferometer measurement document the accuracy of the layer positioning and the performance of this low-cost approach. The filter shows the designed filter dip at 1490 nm, the full width at half maximum (FWHM) of the filter is 1.5 nm and the insertion loss is just 1.3 dB. The process is compatible with a variety of materials, e.g. III-V compounds, silicon, as well as organic materials, facilitating a huge application spectrum for sensors.

  19. Enhanced microwave ferromagnetic resonance absorption and bandwidth using a microstrip meander line with step-impedance low-pass filter in a yttrium iron garnet-gallium arsenide layer structure

    NASA Astrophysics Data System (ADS)

    Qiu, Gang; Tsai, Chen S.; Kobayashi, Masatoshi M.; Wang, Bert S. T.

    2008-04-01

    Simulations of the step-impedance low-pass filter (LPF) in gallium arsenide (GaAs) substrate show that, in contrast to a 50? microstrip, the magnetic fields of the propagating microwaves are heavily concentrated in its inductive elements. The concentrated local magnetic fields facilitate enhanced coupling into an yttrium iron garnet/gadolinium gallium garnet layer over the GaAs substrate and, thus, significantly increase the microwave power absorptions at the ferromagnetic resonance (FMR) frequencies. The large tunable range of FMR frequency and the corresponding S21 and S11 parameters measured have verified the simulation results. Simultaneous enhancement of FMR absorption level and widening of absorption bandwidth has been accomplished in a band-stop filter that utilizes a microstrip meander line with four identical step-impedance LPFs, each of 5.70mm long, inserted in a nonuniform bias magnetic field. A tunable FMR absorption frequency range of 5-21GHz, an absorption level of -35.5dB, and a corresponding 3dB absorption bandwidth as large as 1.70GHz, centered at 20.3GHz, have been demonstrated.

  20. Multi-dimensional tensor-based adaptive filter (TBAF) for low dose x-ray CT

    NASA Astrophysics Data System (ADS)

    Knaup, Michael; Lebedev, Sergej; Sawall, Stefan; Kachelrieß, Marc

    2015-03-01

    Edge-preserving adaptive filtering within CT image reconstruction is a powerful method to reduce image noise and hence to reduce patient dose. However, highly sophisticated adaptive filters typically comprise many parameters which must be adjusted carefully in order to obtain optimal filter performance and to avoid artifacts caused by the filter. In this work we applied an anisotropic tensor-based adaptive image filter (TBAF) to CT image reconstruction, both as an image-based post-processing step, as well as a regularization step within an iterative reconstruction. The TBAF is a generalization of the filter of reference.1 Provided that the image noise (i.e. the variance) of the original image is known for each voxel, we adjust all filter parameters automatically. Hence, the TBAF can be applied to any individual CT dataset without user interaction. This is a crucial feature for a possible application in clinical routine. The TBAF is compared to a well-established adaptive bilateral filter using the same noise adjustment. Although the differences between both filters are subtle, edges and local structures emerge more clearly in the TBAF filtered images while anatomical details are less affected than by the bilateral filter.

  1. Multiple time step molecular dynamics in the optimized isokinetic ensemble steered with the molecular theory of solvation: Accelerating with advanced extrapolation of effective solvation forces

    SciTech Connect

    Omelyan, Igor, E-mail: omelyan@ualberta.ca, E-mail: omelyan@icmp.lviv.ua [National Institute for Nanotechnology, 11421 Saskatchewan Drive, Edmonton, Alberta T6G 2M9 (Canada) [National Institute for Nanotechnology, 11421 Saskatchewan Drive, Edmonton, Alberta T6G 2M9 (Canada); Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta T6G 2G8 (Canada); Institute for Condensed Matter Physics, National Academy of Sciences of Ukraine, 1 Svientsitskii Street, Lviv 79011 (Ukraine); Kovalenko, Andriy, E-mail: andriy.kovalenko@nrc-cnrc.gc.ca [National Institute for Nanotechnology, 11421 Saskatchewan Drive, Edmonton, Alberta T6G 2M9 (Canada) [National Institute for Nanotechnology, 11421 Saskatchewan Drive, Edmonton, Alberta T6G 2M9 (Canada); Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta T6G 2G8 (Canada)

    2013-12-28

    We develop efficient handling of solvation forces in the multiscale method of multiple time step molecular dynamics (MTS-MD) of a biomolecule steered by the solvation free energy (effective solvation forces) obtained from the 3D-RISM-KH molecular theory of solvation (three-dimensional reference interaction site model complemented with the Kovalenko-Hirata closure approximation). To reduce the computational expenses, we calculate the effective solvation forces acting on the biomolecule by using advanced solvation force extrapolation (ASFE) at inner time steps while converging the 3D-RISM-KH integral equations only at large outer time steps. The idea of ASFE consists in developing a discrete non-Eckart rotational transformation of atomic coordinates that minimizes the distances between the atomic positions of the biomolecule at different time moments. The effective solvation forces for the biomolecule in a current conformation at an inner time step are then extrapolated in the transformed subspace of those at outer time steps by using a modified least square fit approach applied to a relatively small number of the best force-coordinate pairs. The latter are selected from an extended set collecting the effective solvation forces obtained from 3D-RISM-KH at outer time steps over a broad time interval. The MTS-MD integration with effective solvation forces obtained by converging 3D-RISM-KH at outer time steps and applying ASFE at inner time steps is stabilized by employing the optimized isokinetic Nosé-Hoover chain (OIN) ensemble. Compared to the previous extrapolation schemes used in combination with the Langevin thermostat, the ASFE approach substantially improves the accuracy of evaluation of effective solvation forces and in combination with the OIN thermostat enables a dramatic increase of outer time steps. We demonstrate on a fully flexible model of alanine dipeptide in aqueous solution that the MTS-MD/OIN/ASFE/3D-RISM-KH multiscale method of molecular dynamics steered by effective solvation forces allows huge outer time steps up to tens of picoseconds without affecting the equilibrium and conformational properties, and thus provides a 100- to 500-fold effective speedup in comparison to conventional MD with explicit solvent. With the statistical-mechanical 3D-RISM-KH account for effective solvation forces, the method provides efficient sampling of biomolecular processes with slow and/or rare solvation events such as conformational transitions of hydrated alanine dipeptide with the mean life times ranging from 30 ps up to 10 ns for “flip-flop” conformations, and is particularly beneficial for biomolecular systems with exchange and localization of solvent and ions, ligand binding, and molecular recognition.

  2. Exact Moments of Filtered Laser Phase Noise

    NASA Astrophysics Data System (ADS)

    Banat, Mohammad M.

    2007-02-01

    In this paper, we derive an exact finite power series expression of the n th-order moment of a complex filtered phase noise random variable. This random variable is usually encountered in the error probability analysis of coherent heterodyne optical receivers. The result is then used to derive an infinite power series expression for the moment generating function of the same random variable. The two expressions represent a novel full statistical characterization of filtered phase noise. They also constitute an important step toward deriving optimal heterodyne receiver designs in the presence of phase noise. In a previous work Banat (J. Opt. Commun., vol. 5, 267 271, Dec. 2004), the author presented an approximate finite power series moment expression for filtered laser phase noise. The new results will be compared to those of Banat (J. Opt. Commun., vol. 5, 267 271, Dec. 2004).

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

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    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.

  4. Spatial-domain design of two-dimensional recursive digital filters

    Microsoft Academic Search

    S. Aly; M. Fahmy

    1980-01-01

    A technique is proposed to design stable two-dimensional (2-D) recursive digital filters that best approximate, in thel_p-sense, a prescribed impulse or step response, using a local state-space model. The Davidon-Fletcher and Powell optimization algorithm is used to minimize the performance measure. Several designs for first-quadrant and asymmetric half-plane filters are solved to illustrate the proposed technique.

  5. Design of a High Efficiency CDS/CDTE Solar Cell with Optimized Step Doping, Film Thickness, and Carrier Lifetime of the Absorption Layer

    NASA Astrophysics Data System (ADS)

    Khosroabadi, S.; Keshmiri, S. H.; Marjani, S.

    2014-12-01

    A high-efficiency CdS/CdTe solar cell with step doped absorber layer, optimized back surface field layer, and long carrier lifetime in the absorption layer was designed. At first, The CdS/CdTe reference cell is simulated and compared with previous experimental data. In order to obtain the highest efficiency, the thickness and step doping of the absorber and back surface field layer were optimized. In addition, the effect of carrier lifetime variation in the CdTe layer on the conversion efficiency of CdTe cell was investigated. Compared with reference cell, Efficiency enhancement of the proposed structure was 4.44%. Under global AM 1.5 conditions, the optimized cell structure had an open-circuit voltage of 0.987 V, a short-circuit current density of 27.9 mA/cm^2 and a fill factor of 82.4%, corresponding to a total area conversion efficiency of 22.76%.

  6. Feasibility study of high frequency step-up transformer linked soft-switching PWM DC-DC converter with tapped inductor filter

    Microsoft Academic Search

    S. Moisseev; K. Suzuoka; T. Ahmed; M. Nakaoka

    2003-01-01

    This paper presents a novel high frequency transformer linked full-bridge type soft-switching phase-shift PWM control DC-DC power converter, which can be used as DC power conditioner for small-scale fuel cell power generation system as well as isolated step-up DC-DC power converter for automotive AC power supply. Using full-bridge soft-switching PWM DC-DC converter topology makes possible to use low voltage high

  7. SU-E-T-23: A Novel Two-Step Optimization Scheme for Tandem and Ovoid (T and O) HDR Brachytherapy Treatment for Locally Advanced Cervical Cancer

    SciTech Connect

    Sharma, M; Todor, D [Virginia Commonwealth University, Richmond, VA (United States); Fields, E [Virginia Commonwealth University, Richmond, Virginia (United States)

    2014-06-01

    Purpose: To present a novel method allowing fast, true volumetric optimization of T and O HDR treatments and to quantify its benefits. Materials and Methods: 27 CT planning datasets and treatment plans from six consecutive cervical cancer patients treated with 4–5 intracavitary T and O insertions were used. Initial treatment plans were created with a goal of covering high risk (HR)-CTV with D90 > 90% and minimizing D2cc to rectum, bladder and sigmoid with manual optimization, approved and delivered. For the second step, each case was re-planned adding a new structure, created from the 100% prescription isodose line of the manually optimized plan to the existent physician delineated HR-CTV, rectum, bladder and sigmoid. New, more rigorous DVH constraints for the critical OARs were used for the optimization. D90 for the HR-CTV and D2cc for OARs were evaluated in both plans. Results: Two-step optimized plans had consistently smaller D2cc's for all three OARs while preserving good D90s for HR-CTV. On plans with “excellent” CTV coverage, average D90 of 96% (range 91–102), sigmoid D2cc was reduced on average by 37% (range 16–73), bladder by 28% (range 20–47) and rectum by 27% (range 15–45). Similar reductions were obtained on plans with “good” coverage, with an average D90 of 93% (range 90–99). For plans with inferior coverage, average D90 of 81%, an increase in coverage to 87% was achieved concurrently with D2cc reductions of 31%, 18% and 11% for sigmoid, bladder and rectum. Conclusions: A two-step DVH-based optimization can be added with minimal planning time increase, but with the potential of dramatic and systematic reductions of D2cc for OARs and in some cases with concurrent increases in target dose coverage. These single-fraction modifications would be magnified over the course of 4–5 intracavitary insertions and may have real clinical implications in terms of decreasing both acute and late toxicity.

  8. Integration of optimization systems in cement industry, and an application of Kalman filter as the input data preprocessors for them

    Microsoft Academic Search

    T. Aizawa; N. Takechi

    1994-01-01

    Many optimization systems are individually optimized, however, they are closely related to each other at various levels. It is, therefore, necessary to integrate those systems if necessary, viewing from the standpoint of the optimization of the whole company. The performance of an individual optimization system largely depends upon the accuracy of the input information. It is, however, difficult to obtain

  9. A Speed-Optimized Systolic Array Processor Architecture for Spatio-Temporal 2-D IIR Broadband Beam Filters

    Microsoft Academic Search

    H. L. P. Arjuna Madanayake; Leonard T. Bruton

    2008-01-01

    For high-speed plane-wave filtering applications, real-time 2-D spatio-temporal linear-array broadband beam filters are required, operating at temporal frame rates in excess of hundreds of megahertz. The corresponding application specific VLSI circuits must have low critical-path latencies. A novel high-speed systolic array architecture for a first-order 2-D broadband frequency-planar spatio-temporal beam filter is proposed for this purpose and employs a field-programmable

  10. Modelling of diffraction grating based optical filters for fluorescence detection of biomolecules

    PubMed Central

    Kova?i?, M.; Kr?, J.; Lipovšek, B.; Topi?, M.

    2014-01-01

    The detection of biomolecules based on fluorescence measurements is a powerful diagnostic tool for the acquisition of genetic, proteomic and cellular information. One key performance limiting factor remains the integrated optical filter, which is designed to reject strong excitation light while transmitting weak emission (fluorescent) light to the photodetector. Conventional filters have several disadvantages. For instance absorbing filters, like those made from amorphous silicon carbide, exhibit low rejection ratios, especially in the case of small Stokes’ shift fluorophores (e.g. green fluorescent protein GFP with ?exc = 480 nm and ?em = 510 nm), whereas interference filters comprising many layers require complex fabrication. This paper describes an alternative solution based on dielectric diffraction gratings. These filters are not only highly efficient but require a smaller number of manufacturing steps. Using FEM-based optical modelling as a design optimization tool, three filtering concepts are explored: (i) a diffraction grating fabricated on the surface of an absorbing filter, (ii) a diffraction grating embedded in a host material with a low refractive index, and (iii) a combination of an embedded grating and an absorbing filter. Both concepts involving an embedded grating show high rejection ratios (over 100,000) for the case of GFP, but also high sensitivity to manufacturing errors and variations in the incident angle of the excitation light. Despite this, simulations show that a 60 times improvement in the rejection ratio relative to a conventional flat absorbing filter can be obtained using an optimized embedded diffraction grating fabricated on top of an absorbing filter. PMID:25071964

  11. A two-step method for the optimization of antenna azimuth\\/tilt and frequency planning in OFDMA multihop networks

    Microsoft Academic Search

    Fernando Gordejuela-sanchez; David López-pérez; Jie Zhang

    2009-01-01

    During the network planning process, it is very important to identify the key network design factors and define how to take them into account to achieve optimally performing networks. The introduction of Relay Stations (RSs) in OFDMA-based networks will bring numerous advantages such as coverage extension and capacity enhancement due to the deployment of new cells and the reduction of

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

    PubMed

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

    2013-01-01

    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

  13. A Gaussian mixture ensemble transform filter

    E-print Network

    Reich, Sebastian

    2011-01-01

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

  14. Search for an Optimal Five-Step Charging Pattern for Li-Ion Batteries Using Consecutive Orthogonal Arrays

    Microsoft Academic Search

    Yi-Hwa Liu; Ching-Hsing Hsieh; Yi-Feng Luo

    2011-01-01

    Lithium-ion (Li-ion) batteries have emerged as the major power source for today's electronic products because they can offer advantages such as high energy density, low maintenance requirement, high open-circuit voltage, low self-discharge rate, and lack of memory effect. The performance and lifespan of Li-ion bat- teries are closely related to the quality of the charging pattern. Therefore, an optimal charging

  15. Definitive Screening Design Optimization of Mass Spectrometry Parameters for Sensitive Comparison of Filter and Solid Phase Extraction Purified, INLIGHT Plasma N-Glycans.

    PubMed

    Hecht, Elizabeth S; McCord, James P; Muddiman, David C

    2015-07-21

    High-throughput, quantitative processing of N-linked glycans would facilitate large-scale studies correlating the glycome with disease and open the field to basic and applied researchers. We sought to meet these goals by coupling filter-aided-N-glycan separation (FANGS) to the individuality normalization when labeling with glycan hydrazide tags (INLIGHT) for analysis of plasma. A quantitative comparison of this method was conducted against solid phase extraction (SPE), a ubiquitous and trusted method for glycan purification. We demonstrate that FANGS-INLIGHT purification was not significantly different from SPE in terms of glycan abundances, variability, functional classes, or molecular weight distributions. Furthermore, to increase the depth of glycome coverage, we executed a definitive screening design of experiments (DOE) to optimize the MS parameters for glycan analyses. We optimized MS parameters across five N-glycan responses using a standard glycan mixture, translated these to plasma and achieved up to a 3-fold increase in ion abundances. PMID:26086806

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

    NASA Technical Reports Server (NTRS)

    Halyo, N.

    1976-01-01

    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.

  17. Optimal Data Distribution for Versatile Finite Impulse Response Filtering on Next-Generation Graphics Hardware Using CUDA

    Microsoft Academic Search

    Patrik Goorts; Sammy Rogmans; Philippe Bekaert

    2009-01-01

    In this paper, we investigate discrete finite impulse response (FIR) filtering of images, while harnessing the powerful computational resources of next-generation GPUs. These novel platforms exhibit a massive data parallel architecture with an advanced SIMT execution model and thread management, to enable designers to better cope with the infamous memory wall, i.e. the growing gap between the cost of data

  18. Digital Control of a Bank of IIR Filters in Optimal Processing of Signals From Pulse Radiation Detectors

    Microsoft Academic Search

    Djordje Aponji; Vojislav Arandjelovi; Mili Stoji

    2006-01-01

    New algorithm for measurement of mean count rate of pulses from radiation detectors is described. The algorithm is based on the control of a bank of digital IIR filters governed by the state of mean count rate-stationary or transient. The algorithm solves successfully the compromise between the contradictory requirements for low statistical fluctuations in steady state and fast response to

  19. Optimal State Estimation for Cavity Optomechanical Systems

    NASA Astrophysics Data System (ADS)

    Wieczorek, Witlef; Hofer, Sebastian G.; Hoelscher-Obermaier, Jason; Riedinger, Ralf; Hammerer, Klemens; Aspelmeyer, Markus

    2015-06-01

    We demonstrate optimal state estimation for a cavity optomechanical system through Kalman filtering. By taking into account nontrivial experimental noise sources, such as colored laser noise and spurious mechanical modes, we implement a realistic state-space model. This allows us to obtain the conditional system state, i.e., conditioned on previous measurements, with a minimal least-squares estimation error. We apply this method to estimate the mechanical state, as well as optomechanical correlations both in the weak and strong coupling regime. The application of the Kalman filter is an important next step for achieving real-time optimal (classical and quantum) control of cavity optomechanical systems.

  20. Mixed Variable Optimization of a Load-Bearing Thermal Insulation System Using a Filter Pattern Search Algorithm

    Microsoft Academic Search

    Mark A. Abramson; Wright-Patterson AFB

    2004-01-01

    This paper describes the optimization of a load-bearing thermal insulation system characterized by hot and cold surfaces with a series of heat intercepts and insulators between them. The optimization problem is represented as a mixed variable programming (MVP) problem with nonlinear constraints, in which the objective is to minimize the power required to maintain the heat intercepts at fixed temperatures

  1. Tyrosine 263 in cyanobacterial phytochrome Cph1 optimizes photochemistry at the prelumi-R?lumi-R step.

    PubMed

    Sineshchekov, Vitaly; Mailliet, Joel; Psakis, Georgios; Feilke, Kathleen; Kopycki, Jakub; Zeidler, Mathias; Essen, Lars-Oliver; Hughes, Jon

    2014-01-01

    We report a low-temperature fluorescence spectroscopy study of the PAS-GAF-PHY sensory module of Cph1 phytochrome, its Y263F mutant (both with known 3D structures) as well as Y263H and Y263S to connect their photochemical parameters with intramolecular interactions. None of the holoproteins showed photochemical activity at low temperature, and the activation barriers for the Pr?lumi-R photoreaction (2.5-3.1 kJ mol(-1)) and fluorescence quantum yields (0.29-0.42) were similar. The effect of the mutations on Pr?Pfr photoconversion efficiency (?Pr?Pfr) was observed primarily at the prelumi-R S0 bifurcation point corresponding to the conical intersection of the energy surfaces at which the molecule relaxes to form lumi-R or Pr, lowering ?Pr?Pfr from 0.13 in the wild type to 0.05-0.07 in the mutants. We suggest that the Ea activation barrier in the Pr* S1 excited state might correspond to the D-ring (C19) carbonyl - H290 hydrogen bond or possibly to the hindrance caused by the C13(1) /C17(1) methyl groups of the C and D rings. The critical role of the tyrosine hydroxyl group can be at the prelumi-R bifurcation point to optimize the yield of the photoprocess and energy storage in the form of lumi-R for subsequent rearrangement processes culminating in Pfr formation. PMID:24571438

  2. Filters for dual band infrared imagers

    Microsoft Academic Search

    Thomas D. Rahmlow Jr.; Jeanne E. Lazo-Wasem; Scott Wilkinson; Flemming Tinker

    2009-01-01

    Dual band infrared imagers require a similar set of filters as are needed by single band infrared imagers but with the added requirement of high transmission in the mid and far infrared. The design of discrete layer filters with optimized dual band transmission is investigated for three types of filters. These are a visible-infrared beamsplitter, a long wavelength edge filter

  3. Optimization of the polarized Klein tunneling currents in a sub-lattice: pseudo-spin filters and latticetronics in graphene ribbons.

    PubMed

    López, Luis I A; Yaro, Simeón Moisés; Champi, A; Ujevic, Sebastian; Mendoza, Michel

    2014-02-12

    We found that with an increase of the potential barrier applied to metallic graphene ribbons, the Klein tunneling current decreases until it is totally destroyed and the pseudo-spin polarization increases until it reaches its maximum value when the current is zero. This inverse relation disfavors the generation of polarized currents in a sub-lattice. In this work we discuss the pseudo-spin control (polarization and inversion) of the Klein tunneling currents, as well as the optimization of these polarized currents in a sub-lattice, using potential barriers in metallic graphene ribbons. Using density of states maps, conductance results, and pseudo-spin polarization information (all of them as a function of the energy V and width of the barrier L), we found (V, L) intervals in which the polarized currents in a given sub-lattice are maximized. We also built parallel and series configurations with these barriers in order to further optimize the polarized currents. A systematic study of these maps and barrier configurations shows that the parallel configurations are good candidates for optimization of the polarized tunneling currents through the sub-lattice. Furthermore, we discuss the possibility of using an electrostatic potential as (i) a pseudo-spin filter or (ii) a pseudo-spin inversion manipulator, i.e. a possible latticetronic of electronic currents through metallic graphene ribbons. The results of this work can be extended to graphene nanostructures. PMID:24441476

  4. Development of superconductive microwave filters for mobile communications and filter banks

    Microsoft Academic Search

    B. Marcilhac; Y. Lemaitre; D. Mansart; J. C. Mage

    1999-01-01

    The development of superconductive microwave filters connected to the use of cooled electronics is now in the critical phase of system integration. All the different steps of filter development, design and fabrication must be controlled, reproducible and technically realisable by conventional microelectronics tools. We developed filters for mobile communications and filter banks with the goal of optimising these aspects. Lanthanum

  5. Optimal Attitude and Position Determination from Line-of-Sight

    E-print Network

    Crassidis, John L.

    Roberto Alonso John L. Junkins Abstract In this paper an optimal solution to the problem of determining is derived from a generalized predictive filter for nonlinear systems. This uses a one time-step ahead is noniterative and is computationally efficient, which has significant advantages over traditional nonlinear

  6. Paper AAS 00-268 OPTIMAL ATTITUDE AND POSITION

    E-print Network

    Crassidis, John L.

    . Crassidis Roberto Alonso John L. Junkins Center for Mechanics and Control Department of Aerospace L. Junkins In this paper an optimal solution to the problem of determining both vehicle attitude- dictive filter for nonlinear systems. This uses a one time-step ahead approach to propagate a simple

  7. Disk filter

    DOEpatents

    Bergman, Werner (Pleasanton, CA)

    1986-01-01

    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.

  8. Filter arrangement

    SciTech Connect

    Hancock, T.M.

    1981-06-09

    A filter arrangement is described that includes a venturi element carried within a tubular filter by a flexible attachment ring at one end of the filter removably securing the filter in the aperture of an apertured plate member in a gas filtration system. The outermost diameter of the venturi element is slightly less than the diameter of the aperture to accommodate withdrawal of the venturi element from either side of the plate attendant to installation and removal of the filter arrangement.

  9. Optimization of an analytical methodology for the simultaneous determination of different classes of ultraviolet filters in cosmetics by pressurized liquid extraction-gas chromatography tandem mass spectrometry.

    PubMed

    Vila, Marlene; Lamas, J Pablo; Garcia-Jares, Carmen; Dagnac, Thierry; Llompart, Maria

    2015-07-31

    A methodology based on pressurized liquid extraction (PLE) followed by gas chromatography-tandem mass spectrometry (GC-MS/MS) has been developed for the simultaneous analysis of different classes of UV filters including methoxycinnamates, benzophenones, salicylates, p-aminobenzoic acid derivatives, and others in cosmetic products. The extractions were carried out in 1mL extraction cells and the amount of sample extracted was only 100mg. The experimental conditions, including the acetylation of the PLE extracts to improve GC performance, were optimized by means of experimental design tools. The two main factors affecting the PLE procedure such as solvent type and extraction temperature were assessed. The use of a matrix matched approach consisting of the addition of 10?L of diluted commercial cosmetic oil avoided matrix effects. Good linearity (R(2)>0.9970), quantitative recoveries (>80% for most of compounds, excluding three banned benzophenones) and satisfactory precision (RSD<10% in most cases) were achieved under the optimal conditions. The validated methodology was successfully applied to the analysis of different types of cosmetic formulations including sunscreens, hair products, nail polish, and lipsticks, amongst others. PMID:26091782

  10. Filtering Water

    NSDL National Science Digital Library

    Brieske, Joel A.

    2003-01-01

    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.

  11. Hot-gas filter manufacturing assessments: Volume 5. Final report, April 15, 1997

    SciTech Connect

    Boss, D.E.

    1997-12-31

    The development of advanced filtration media for advanced fossil-fueled power generating systems is a critical step in meeting the performance and emissions requirements for these systems. While porous metal and ceramic candle-filters have been available for some time, the next generation of filters will include ceramic-matrix composites (CMCs), intermetallic alloys, and alternate filter geometries. The goal of this effort was to perform a cursory review of the manufacturing processes used by 5 companies developing advanced filters from the perspective of process repeatability and the ability for their processes to be scale-up to production volumes. It was found that all of the filter manufacturers had a solid understanding of the product development path. Given that these filters are largely developmental, significant additional work is necessary to understand the process-performance relationships and projecting manufacturing costs. While each organization had specific needs, some common among all of the filter manufacturers were access to performance testing of the filters to aide process/product development, a better understanding of the stresses the filters will see in service for use in structural design of the components, and a strong process sensitivity study to allow optimization of processing.

  12. Analysis of plasticizers in poly(vinyl chloride) medical devices for infusion and artificial nutrition: comparison and optimization of the extraction procedures, a pre-migration test step.

    PubMed

    Bernard, Lise; Cueff, Régis; Bourdeaux, Daniel; Breysse, Colette; Sautou, Valérie

    2015-02-01

    Medical devices (MDs) for infusion and enteral and parenteral nutrition are essentially made of plasticized polyvinyl chloride (PVC). The first step in assessing patient exposure to these plasticizers, as well as ensuring that the MDs are free from di(2-ethylhexyl) phthalate (DEHP), consists of identifying and quantifying the plasticizers present and, consequently, determining which ones are likely to migrate into the patient's body. We compared three different extraction methods using 0.1 g of plasticized PVC: Soxhlet extraction in diethyl ether and ethyl acetate, polymer dissolution, and room temperature extraction in different solvents. It was found that simple room temperature chloroform extraction under optimized conditions (30 min, 50 mL) gave the best separation of plasticizers from the PVC matrix, with extraction yields ranging from 92 to 100% for all plasticizers. This result was confirmed by supplemented Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR) and gravimetric analyses. The technique was used on eight marketed medical devices and showed that they contained different amounts of plasticizers, ranging from 25 to 36% of the PVC weight. These yields, associated with the individual physicochemical properties of each plasticizer, highlight the need for further migration studies. PMID:25577357

  13. Modeling and optimization of ultrasound-assisted extraction of polyphenolic compounds from Aronia melanocarpa by-products from filter-tea factory.

    PubMed

    Rami?, Milica; Vidovi?, Senka; Zekovi?, Zoran; Vladi?, Jelena; Cvejin, Aleksandra; Pavli?, Branimir

    2015-03-01

    Aronia melanocarpa by-product from filter-tea factory was used for the preparation of extracts with high content of bioactive compounds. Extraction process was accelerated using sonication. Three level, three variable face-centered cubic experimental design (FCD) with response surface methodology (RSM) was used for optimization of extraction in terms of maximized yields for total phenolics (TP), flavonoids (TF), anthocyanins (MA) and proanthocyanidins (TPA) contents. Ultrasonic power (X?: 72-216 W), temperature (X?: 30-70 °C) and extraction time (X?: 30-90 min) were investigated as independent variables. Experimental results were fitted to a second-order polynomial model where multiple regression analysis and analysis of variance were used to determine fitness of the model and optimal conditions for investigated responses. Three-dimensional surface plots were generated from the mathematical models. The optimal conditions for ultrasound-assisted extraction of TP, TF, MA and TPA were: X?=206.64 W, X?=70 °C, X?=80.1 min; X?=210.24 W, X?=70 °C, X?=75 min; X?=216 W, X?=70 °C, X?=45.6 min and X?=199.44 W, X?=70 °C, X?=89.7 min, respectively. Generated model predicted values of the TP, TF, MA and TPA to be 15.41 mg GAE/ml, 9.86 mg CE/ml, 2.26 mg C3G/ml and 20.67 mg CE/ml, respectively. Experimental validation was performed and close agreement between experimental and predicted values was found (within 95% confidence interval). PMID:25454824

  14. Labyrinth stepped seal geometric optimization 

    E-print Network

    Wernig, Marcus Daniel

    1995-01-01

    High-speed rotating machinery poses a challenging problem to designers and engineers. Interference between rotating and stationary elements can result in excessive wear, decreased machine performance, or machine failure. Labyrinth seals present a...

  15. On Wiener-type filters in SPECT

    Microsoft Academic Search

    J-P Guillement; R G Novikov

    2008-01-01

    For 2D data with Poisson noise we give explicit formulae for the optimal space-invariant Wiener-type filter with some a priori geometric restrictions on the window function. We show that, under some natural geometric condition, this restrictedly optimal Wiener-type filter admits a very efficient approximation by an approximately optimal filter with an unknown object power spectrum. Generalizations to the case of

  16. Neutral density filters with Risley prisms: analysis and design.

    PubMed

    Duma, Virgil-Florin; Nicolov, Mirela

    2009-05-10

    We achieve the analysis and design of optical attenuators with double-prism neutral density filters. A comparative study is performed on three possible device configurations; only two are presented in the literature but without their design calculus. The characteristic parameters of this optical attenuator with Risley translating prisms for each of the three setups are defined and their analytical expressions are derived: adjustment scale (attenuation range) and interval, minimum transmission coefficient and sensitivity. The setups are compared to select the optimal device, and, from this study, the best solution for double-prism neutral density filters, both from a mechanical and an optical point of view, is determined with two identical, symmetrically movable, no mechanical contact prisms. The design calculus of this optimal device is developed in essential steps. The parameters of the prisms, particularly their angles, are studied to improve the design, and we demonstrate the maximum attenuation range that this type of attenuator can provide. PMID:19424388

  17. Optimization of the performance of a thermophilic biotrickling filter for alpha-pinene removal from polluted air.

    PubMed

    Montes, M; Veiga, M C; Kennes, C

    2014-01-01

    Biodegradation of alpha-pinene was investigated in a biological thermophilic trickling filter, using a lava rock and polymer beads mixture as packing material. Partition coefficient (PC) between alpha-pinene and the polymeric material (Hytrel G3548 L) was measured at 50 degrees C. PCs of 57 and 846 were obtained between the polymer and either the water or the gas phase, respectively. BTF experiments were conducted under continuous load feeding. The effect of yeast extract (YE) addition in the recirculating nutrient medium was evaluated. There was a positive relationship between alpha-pinene biodegradation, CO2 production and YE addition. A maximum elimination capacity (ECmax) of 98.9 g m(-3) h(-1) was obtained for an alpha-pinene loading rate of about 121 g m(-3) h(-1) in the presence of 1 g L(-1) YE. The ECmax was reduced by half in the absence of YE. It was also found that a decrease in the liquid flow rate enhances alpha-pinene biodegradation by increasing the ECmax up to 103 gm(-3) h(-1) with a removal efficiency close to 90%. The impact of short-term shock-loads (6 h) was tested under different process conditions. Increasing the pollutant load either 10- or 20-fold resulted in a sudden drop in the BTF's removal capacity, although this effect was attenuated in the presence of YE. PMID:25145201

  18. 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)

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

    2012-12-01

    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.

  19. Water Filters

    NASA Technical Reports Server (NTRS)

    1993-01-01

    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.

  20. SOLVING A HYDTROTREATER FEED FILTER FOULING PROBLEM

    Microsoft Academic Search

    X. A. Wu; K. H. Chung

    2008-01-01

    Feed filters were installed in Syncrude hydrotreater units to protect the catalyst beds from plugging by fine solids in the feed. Severe filter fouling occurred after a process flow sheet change. The root cause of fouling was revealed through a step-by-step scientific investigation. It was first confirmed that the fouling problem was related to a process flow sheet change that

  1. Biological Filters.

    ERIC Educational Resources Information Center

    Klemetson, S. L.

    1978-01-01

    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)

  2. Method of statistical filtering

    NASA Technical Reports Server (NTRS)

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

    1970-01-01

    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.

  3. Water Filters

    NASA Technical Reports Server (NTRS)

    1987-01-01

    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.

  4. Optimization of a two-step process comprising lipase catalysis and thermal cyclization improves the efficiency of synthesis of six-membered cyclic carbonate from trimethylolpropane and dimethylcarbonate.

    PubMed

    Bornadel, Amin; Hatti-Kaul, Rajni; Sörensen, Kent; Lundmark, Stefan; Pyo, Sang-Hyun

    2013-01-01

    Six-membered cyclic carbonates are potential monomers for phosgene and/or isocyanate free polycarbonates and polyurethanes via ring-opening polymerization. A two-step process for their synthesis comprising lipase-catalyzed transesterification of a polyol, trimethylolpropane (TMP) with dimethylcarbonate (DMC) in a solvent-free system followed by thermal cyclization was optimized to improve process efficiency and selectivity. Using full factorial designed experiments and partial least squares (PLS) modeling for the reaction catalyzed by Novozym®435 (N435; immobilized Candida antarctica lipase B), the optimum conditions for obtaining either high proportion of monocarbonated TMP and TMP-cyclic-carbonate (3 and 4), or dicarbonated TMP and monocarbonated TMP-cyclic-carbonate (5 and 6) were found. The PLS model predicted that the reactions using 15%-20% (w/w) N435 at DMC:TMP molar ratio of 10-30 can reach about 65% total yield of 3 and 4 within 10 h, and 65%-70% total yield of 5 and 6 within 32-37 h, respectively. High consistency between the predicted results and empirical data was shown with 66.1% yield of 3 and 4 at 7 h and 67.4% yield of 5 and 6 at 35 h, using 18% (w/w) biocatalyst and DMC:TMP molar ratio of 20. Thermal cyclization of the product from 7 h reaction, at 110°C in the presence of acetonitrile increased the overall yield of cyclic carbonate 4 from about 2% to more than 75% within 24 h. N435 was reused for five consecutive batches, 10 h each, to give 3+4 with a yield of about 65% in each run. PMID:23125051

  5. Orbit determination via adaptive Gaussian swarm optimization

    NASA Astrophysics Data System (ADS)

    Kiani, Maryam; Pourtakdoust, Seid H.

    2015-02-01

    Accurate orbit determination (OD) is vital for every space mission. This paper proposes a novel heuristic filter based on adaptive sample-size Gaussian swarm optimization (AGSF). The proposed estimator considers the OD as a stochastic dynamic optimization problem that utilizes a swarm of particles in order to find the best estimation at every time step. One of the key contributions of this paper is the adaptation of the swarm size using a weighted variance approach. The proposed strategy is simulated for a low Earth orbit (LEO) OD problem utilizing geomagnetic field measurements at 700 km altitude. The performance of the proposed AGSF is verified using Monte Carlo simulation whose results are compared with other advanced sample based nonlinear filters. It is demonstrated that the adopted filter achieves about 2.5 km accuracy in position estimation that fulfills the essential requirements of accuracy and convergence time for OD problem.

  6. Design of FIR digital filters and filter banks by neural networks

    Microsoft Academic Search

    Yue-Dar Jou; Fu-Kun Chen; Lo-Chyuan Su; Shun-Min Wang

    2007-01-01

    The design of digital filters can be formulated as to solve a system of linear equations. This is completed by solving a system of linear equations or by using some matrix properties to simplify the optimization. The proposed approach establishes the quadratic error difference of the filter optimization in the frequency domain as the Lyapunov energy function. Consequently, the optimal

  7. Multiresolution bilateral filtering for image denoising.

    PubMed

    Zhang, Ming; Gunturk, Bahadir K

    2008-12-01

    The bilateral filter is a nonlinear filter that does spatial averaging without smoothing edges; it has shown to be an effective image denoising technique. An important issue with the application of the bilateral filter is the selection of the filter parameters, which affect the results significantly. There are two main contributions of this paper. The first contribution is an empirical study of the optimal bilateral filter parameter selection in image denoising applications. The second contribution is an extension of the bilateral filter: multiresolution bilateral filter, where bilateral filtering is applied to the approximation (low-frequency) subbands of a signal decomposed using a wavelet filter bank. The multiresolution bilateral filter is combined with wavelet thresholding to form a new image denoising framework, which turns out to be very effective in eliminating noise in real noisy images. Experimental results with both simulated and real data are provided. PMID:19004705

  8. Robust Object Tracking via Hierarchical Particle Filter

    Microsoft Academic Search

    Wei Sun; Bao-long Guo

    2008-01-01

    A potential weakness of generic particle filters discussed above is that the particle-based approximation of filtered density is not sufficient to characterize the tail behavior of true density, due to the use of finite mixture approximation; To alleviate this problem, In this paper we propose a general hierarchical particle filtering framework for designing an optimal proposal distribution. The essential idea

  9. Stack filter classifiers

    SciTech Connect

    Porter, Reid B [Los Alamos National Laboratory; Hush, Don [Los Alamos National Laboratory

    2009-01-01

    Just as linear models generalize the sample mean and weighted average, weighted order statistic models generalize the sample median and weighted median. This analogy can be continued informally to generalized additive modeels in the case of the mean, and Stack Filters in the case of the median. Both of these model classes have been extensively studied for signal and image processing but it is surprising to find that for pattern classification, their treatment has been significantly one sided. Generalized additive models are now a major tool in pattern classification and many different learning algorithms have been developed to fit model parameters to finite data. However Stack Filters remain largely confined to signal and image processing and learning algorithms for classification are yet to be seen. This paper is a step towards Stack Filter Classifiers and it shows that the approach is interesting from both a theoretical and a practical perspective.

  10. Filtering apparatus

    DOEpatents

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

    1992-01-01

    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.

  11. Filtering apparatus

    DOEpatents

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

    1992-09-01

    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.

  12. Speed adaptation as Kalman filtering

    Microsoft Academic Search

    Jose F. Barraza; Norberto M. Grzywacz

    2008-01-01

    If the purpose of adaptation is to fit sensory systems to different environments, it may implement an optimization of the system. What the optimum is depends on the statistics of these environments. Therefore, the system should update its parameters as the environment changes. A Kalman-filtering strategy performs such an update optimally by combining current estimations of the environment with those

  13. Aquatic Plants Aid Sewage Filter

    NASA Technical Reports Server (NTRS)

    Wolverton, B. C.

    1985-01-01

    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.

  14. Water Filter

    NSDL National Science Digital Library

    WGBH Boston

    2002-01-01

    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.

  15. Microfabrication of three-dimensional filters for liposome extrusion

    NASA Astrophysics Data System (ADS)

    Baldacchini, Tommaso; Nuñez, Vicente; LaFratta, Christopher N.; Grech, Joseph S.; Vullev, Valentine I.; Zadoyan, Ruben

    2015-03-01

    Liposomes play a relevant role in the biomedical field of drug delivery. The ability of these lipid vesicles to encapsulate and transport a variety of bioactive molecules has fostered their use in several therapeutic applications, from cancer treatments to the administration of drugs with antiviral activities. Size and uniformity are key parameters to take into consideration when preparing liposomes; these factors greatly influence their effectiveness in both in vitro and in vivo experiments. A popular technique employed to achieve the optimal liposome dimension (around 100 nm in diameter) and uniform size distribution is repetitive extrusion through a polycarbonate filter. We investigated two femtosecond laser direct writing techniques for the fabrication of three-dimensional filters within a microfluidics chip for liposomes extrusion. The miniaturization of the extrusion process in a microfluidic system is the first step toward a complete solution for lab-on-a-chip preparation of liposomes from vesicles self-assembly to optical characterization.

  16. Holographic photopolymer linear variable filter with enhanced blue reflection.

    PubMed

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

    2014-03-12

    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

  17. Holographic Photopolymer Linear Variable Filter with Enhanced Blue Reflection

    PubMed Central

    2015-01-01

    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

  18. Stepped nozzle

    DOEpatents

    Sutton, George P. (Danville, CA)

    1998-01-01

    An insert 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.

  19. Stepped nozzle

    DOEpatents

    Sutton, G.P.

    1998-07-14

    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.

  20. Filters for High Rate Pulse Processing

    E-print Network

    Alpert, B K; Bennett, D A; Doriese, W B; Fowler, J W; Hoover, A S; Rabin, M W; Ullom, J N

    2012-01-01

    We introduce a filter-construction method for pulse processing that differs in two respects from that in standard optimal filtering, in which the average pulse shape and noise-power spectral density are combined to create a convolution filter for estimating pulse heights. First, the proposed filters are computed in the time domain, to avoid periodicity artifacts of the discrete Fourier transform, and second, orthogonality constraints are imposed on the filters, to reduce the filtering procedure's sensitivity to unknown baseline height and pulse tails. We analyze the proposed filters, predicting energy resolution under several scenarios, and apply the filters to high-rate pulse data from gamma-rays measured by a transition-edge-sensor microcalorimeter.

  1. Filters for High Rate Pulse Processing

    E-print Network

    B. K. Alpert; R. D. Horansky; D. A. Bennett; W. B. Doriese; J. W. Fowler; A. S. Hoover; M. W. Rabin; J. N. Ullom

    2012-12-07

    We introduce a filter-construction method for pulse processing that differs in two respects from that in standard optimal filtering, in which the average pulse shape and noise-power spectral density are combined to create a convolution filter for estimating pulse heights. First, the proposed filters are computed in the time domain, to avoid periodicity artifacts of the discrete Fourier transform, and second, orthogonality constraints are imposed on the filters, to reduce the filtering procedure's sensitivity to unknown baseline height and pulse tails. We analyze the proposed filters, predicting energy resolution under several scenarios, and apply the filters to high-rate pulse data from gamma-rays measured by a transition-edge-sensor microcalorimeter.

  2. Filters for dual band infrared imagers

    NASA Astrophysics Data System (ADS)

    Rahmlow, Thomas D., Jr.; Lazo-Wasem, Jeanne E.; Wilkinson, Scott; Tinker, Flemming

    2009-05-01

    Dual band infrared imagers require a similar set of filters as are needed by single band infrared imagers but with the added requirement of high transmission in the mid and far infrared. The design of discrete layer filters with optimized dual band transmission is investigated for three types of filters. These are a visible-infrared beamsplitter, a long wavelength edge filter and a dual bandpass cold filter. These designs illustrate the role that harmonic reflection bands can play in the design of dual band filters. The visible reflection beamsplitter design does not have harmonics in the infrared but requires additional layers to reduce reflection at mid and long wavelengths. The long wavelength edge filter requires suppression of the second and third harmonics while the sensor band pass cold filter can use harmonics to advantage. Design techniques are discussed and the results of an initial set of fabrication runs are presented to assess the sensitivity of example designs to manufacturing errors.

  3. Testing Dual Rotary Filters - 12373

    SciTech Connect

    Herman, D.T.; Fowley, M.D.; Stefanko, D.B. [Savannah River National Laboratory (United States); Shedd, D.A.; Houchens, C.L. [Savannah River Remediation, Savannah River Site, Aiken, SC 29808 (United States)

    2012-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

  5. Method and system for training dynamic nonlinear adaptive filters which have embedded memory

    NASA Technical Reports Server (NTRS)

    Rabinowitz, Matthew (Inventor)

    2002-01-01

    Described herein is a method and system for training nonlinear adaptive filters (or neural networks) which have embedded memory. Such memory can arise in a multi-layer finite impulse response (FIR) architecture, or an infinite impulse response (IIR) architecture. We focus on filter architectures with separate linear dynamic components and static nonlinear components. Such filters can be structured so as to restrict their degrees of computational freedom based on a priori knowledge about the dynamic operation to be emulated. The method is detailed for an FIR architecture which consists of linear FIR filters together with nonlinear generalized single layer subnets. For the IIR case, we extend the methodology to a general nonlinear architecture which uses feedback. For these dynamic architectures, we describe how one can apply optimization techniques which make updates closer to the Newton direction than those of a steepest descent method, such as backpropagation. We detail a novel adaptive modified Gauss-Newton optimization technique, which uses an adaptive learning rate to determine both the magnitude and direction of update steps. For a wide range of adaptive filtering applications, the new training algorithm converges faster and to a smaller value of cost than both steepest-descent methods such as backpropagation-through-time, and standard quasi-Newton methods. We apply the algorithm to modeling the inverse of a nonlinear dynamic tracking system 5, as well as a nonlinear amplifier 6.

  6. Improving Filtering for Computer Graphics 

    E-print Network

    Manson, Josiah

    2014-04-30

    voxelizations of objects, which is the first step in 3D printing. I later improved my method to handle more filters. The resulting algorithm creates higher-quality images than commercial software such as Adobe Acrobat and is several times faster than the most...

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

    PubMed Central

    Cui, Fengjie; Zhao, Liming

    2012-01-01

    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

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

    SciTech Connect

    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

    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).

  9. Complete CAD Based Design of Microstrip Dual Mode Hexagonal Loop Resonator Filter

    Microsoft Academic Search

    Shubhendu Bhardwaj; Gaurav Singh Teotia; Nikhil Grover; Sushrut Das

    2011-01-01

    In this paper, we propose a hexagonal microstrip dual - mode band pass filter by optimizing various geometrical parameters associated with the filter geometry using IE3D full- wave simulation software. The response of the optimized filter is studied and analyzed and the results have been reported. Work also explores the possibility of changing the type of the filter response from

  10. Generating an optimal DTM from airborne laser scanning data for landslide mapping in a tropical forest environment

    NASA Astrophysics Data System (ADS)

    Razak, Khamarrul Azahari; Santangelo, Michele; Van Westen, Cees J.; Straatsma, Menno W.; de Jong, Steven M.

    2013-05-01

    Landslide inventory maps are fundamental for assessing landslide susceptibility, hazard, and risk. In tropical mountainous environments, mapping landslides is difficult as rapid and dense vegetation growth obscures landslides soon after their occurrence. Airborne laser scanning (ALS) data have been used to construct the digital terrain model (DTM) under dense vegetation, but its reliability for landslide recognition in the tropics remains surprisingly unknown. This study evaluates the suitability of ALS for generating an optimal DTM for mapping landslides in the Cameron Highlands, Malaysia. For the bare-earth extraction, we used hierarchical robust filtering algorithm and a parameterization with three sequential filtering steps. After each filtering step, four interpolations techniques were applied, namely: (i) the linear prediction derived from the SCOP++ (SCP), (ii) the inverse distance weighting (IDW), (iii) the natural neighbor (NEN) and (iv) the topo-to-raster (T2R). We assessed the quality of 12 DTMs in two ways: (1) with respect to 448 field-measured terrain heights and (2) based on the interpretability of landslides. The lowest root-mean-square error (RMSE) was 0.89 m across the landscape using three filtering steps and linear prediction as interpolation method. However, we found that a less stringent DTM filtering unveiled more diagnostic micro-morphological features, but also retained some of vegetation. Hence, a combination of filtering steps is required for optimal landslide interpretation, especially in forested mountainous areas. IDW was favored as the interpolation technique because it combined computational times more reasonably without adding artifacts to the DTM than T2R and NEN, which performed relatively well in the first and second filtering steps, respectively. The laser point density and the resulting ground point density after filtering are key parameters for producing a DTM applicable to landslide identification. The results showed that the ALS-derived DTMs allowed mapping and classifying landslides beneath equatorial mountainous forests, leading to a better understanding of hazardous geomorphic problems in tropical regions.

  11. Risk-sensitive filtering and smoothing via reference probability methods

    Microsoft Academic Search

    Subhrakanti Dey; John B. Moore

    1997-01-01

    We address the risk-sensitive filtering problem which is minimizing the expectation of the exponential of the squared estimation error multiplied by a risk-sensitive parameter. Such filtering can be more robust to plant and noise uncertainty than minimum error variance filtering. Although optimizing a differently formulated performance index to that of the so-called H? filtering, risk-sensitive filtering leads to a worst

  12. Supervised particle filter for tracking 2D human pose in monocular video

    Microsoft Academic Search

    Suman Sedai; Du Q. Huynh; Mohammed Bennamoun

    2011-01-01

    In this paper, we propose a hybrid method that combines supervised learning and particle filtering to track the 2D pose of a human subject in monocular video sequences. Our approach, which we call a supervised particle filter method, consists of two steps: the training step and the tracking step. In the training step, we use a supervised learning method to

  13. The Lockheed alternate partial polarizer universal filter

    NASA Technical Reports Server (NTRS)

    Title, A. M.

    1976-01-01

    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.

  14. How anti-aliasing filter affects image contrast: An analysis from majorization theory perspective

    Microsoft Academic Search

    Ketan Tang; Oscar C. Au; Lu Fang; Zhiding Yu; Yuanfang Guo

    2011-01-01

    When we design an anti-aliasing low pass filter, it is usually an IIR filter. We need to truncate the filter to an FIR filter. One may think that the more taps there are, the better the image quality is. However, we find that there exists an optimal value of tap number that will give the best visual quality. Filters with

  15. Water Filters

    NASA Technical Reports Server (NTRS)

    1988-01-01

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

  16. Filter apparatus

    DOEpatents

    Kuban, Daniel P. (Oak Ridge, TN); Singletary, B. Huston (Oak Ridge, TN); Evans, John H. (Rockwood, TN)

    1984-01-01

    A plurality of holding tubes are respectively mounted in apertures in a partition plate fixed in a housing receiving gas contaminated with particulate material. A filter cartridge is removably held in each holding tube, and the cartridges and holding tubes are arranged so that gas passes through apertures therein and across the partition plate while particulate material is collected in the cartridges. Replacement filter cartridges are respectively held in holding canisters mounted on a support plate which can be secured to the aforesaid housing, and screws mounted on said canisters are arranged to push replacement cartridges into the cartridge holding tubes and thereby eject used cartridges therefrom.

  17. The intractable cigarette ‘filter problem’

    PubMed Central

    2011-01-01

    Background When lung cancer fears emerged in the 1950s, cigarette companies initiated a shift in cigarette design from unfiltered to filtered cigarettes. Both the ineffectiveness of cigarette filters and the tobacco industry's misleading marketing of the benefits of filtered cigarettes have been well documented. However, during the 1950s and 1960s, American cigarette companies spent millions of dollars to solve what the industry identified as the ‘filter problem’. These extensive filter research and development efforts suggest a phase of genuine optimism among cigarette designers that cigarette filters could be engineered to mitigate the health hazards of smoking. Objective This paper explores the early history of cigarette filter research and development in order to elucidate why and when seemingly sincere filter engineering efforts devolved into manipulations in cigarette design to sustain cigarette marketing and mitigate consumers' concerns about the health consequences of smoking. Methods Relevant word and phrase searches were conducted in the Legacy Tobacco Documents Library online database, Google Patents, and media and medical databases including ProQuest, JSTOR, Medline and PubMed. Results 13 tobacco industry documents were identified that track prominent developments involved in what the industry referred to as the ‘filter problem’. These reveal a period of intense focus on the ‘filter problem’ that persisted from the mid-1950s to the mid-1960s, featuring collaborations between cigarette producers and large American chemical and textile companies to develop effective filters. In addition, the documents reveal how cigarette filter researchers' growing scientific knowledge of smoke chemistry led to increasing recognition that filters were unlikely to offer significant health protection. One of the primary concerns of cigarette producers was to design cigarette filters that could be economically incorporated into the massive scale of cigarette production. The synthetic plastic cellulose acetate became the fundamental cigarette filter material. By the mid-1960s, the meaning of the phrase ‘filter problem’ changed, such that the effort to develop effective filters became a campaign to market cigarette designs that would sustain the myth of cigarette filter efficacy. Conclusions This study indicates that cigarette designers at Philip Morris, British-American Tobacco, Lorillard and other companies believed for a time that they might be able to reduce some of the most dangerous substances in mainstream smoke through advanced engineering of filter tips. In their attempts to accomplish this, they developed the now ubiquitous cellulose acetate cigarette filter. By the mid-1960s cigarette designers realised that the intractability of the ‘filter problem’ derived from a simple fact: that which is harmful in mainstream smoke and that which provides the smoker with ‘satisfaction’ are essentially one and the same. Only in the wake of this realisation did the agenda of cigarette designers appear to transition away from mitigating the health hazards of smoking and towards the perpetuation of the notion that cigarette filters are effective in reducing these hazards. Filters became a marketing tool, designed to keep and recruit smokers as consumers of these hazardous products. PMID:21504917

  18. Sub-wavelength efficient polarization filter (SWEP filter)

    DOEpatents

    Simpson, Marcus L.; Simpson, John T.

    2003-12-09

    A polarization sensitive filter includes a first sub-wavelength resonant grating structure (SWS) for receiving incident light, and a second SWS. The SWS are disposed relative to one another such that incident light which is transmitted by the first SWS passes through the second SWS. The filter has a polarization sensitive resonance, the polarization sensitive resonance substantially reflecting a first polarization component of incident light while substantially transmitting a second polarization component of the incident light, the polarization components being orthogonal to one another. A method for forming polarization filters includes the steps of forming first and second SWS, the first and second SWS disposed relative to one another such that a portion of incident light applied to the first SWS passes through the second SWS. A method for separating polarizations of light, includes the steps of providing a filter formed from a first and second SWS, shining incident light having orthogonal polarization components on the first SWS, and substantially reflecting one of the orthogonal polarization components while substantially transmitting the other orthogonal polarization component. A high Q narrowband filter includes a first and second SWS, the first and second SWS are spaced apart a distance being at least one half an optical wavelength.

  19. 2-Step IMAT and 2-Step IMRT: a geometrical approach.

    PubMed

    Bratengeier, Klaus

    2005-03-01

    The purpose of this paper is to develop a method that reduces the number of segments for intensity modulated arc therapy (IMAT) and intensity modulated radiotherapy (IMRT) for concave target volumes (TV). The aim was to utilize no more than two intensity levels per organ at risk (OAR) and to derive both optimal segment widths and weights from geometric considerations. Brahme's model of an annular target surrounding a circular OAR was used as test model. Brahme's solution was substituted by a single segment added to a simple field blocking the OAR. Width and weight of the segment were the free parameters to optimize. The objective function to minimize was the root mean square (rms) error of the dose in the target volume. One boundary condition was--neglecting scatter--"zero-dose" to the OAR. The resulting rules for width and weight of the additive segment are referred to as "optimized 2-Step IMAT" and "2-Step IMRT." The recommendations were applied to some simplified plans representing clinical cases using a commercial planning system. Optimized 2-Step IMAT improved the rms by a factor of 4 with respect to techniques simply blocking the OAR. The additional segment reduced the rms below 3% for cases with gaps between OAR and TV larger than 8% of the TV diameter. The results for 2-Step IMAT are applicable to IMRT and aperture modulated arc therapy (AMAT). 2-Step IMAT can be utilized for noncylindrical cases and for more than one OAR. A geometrical and topological approach to IMAT and IMRT can be useful to understand fluence profiles. The results could be applied to ameliorate other topology-based procedures used in some planning systems. Basic mechanisms of 2-Step IMAT can assist with the creation of rules for adaptive IMRT to compensate for patient motion. PMID:15839350

  20. Nonlinear Filtering with Fractional Brownian Motion

    SciTech Connect

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

    2002-12-19

    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.

  1. Fast Kalman filtering on quasilinear dendritic trees

    Microsoft Academic Search

    Liam Paninski

    2010-01-01

    Optimal filtering of noisy voltage signals on dendritic trees is a key problem in compu- tational cellular neuroscience. However, the state variable in this problem — the vector of voltages at every compartment — is very high-dimensional: realistic multicompartmental models often have on the order of N = 104 compartments. Standard implementations of the Kalman filter require O(N 3) time

  2. Phosphorus Filter

    USGS Multimedia Gallery

    Tom Kehler, fishery biologist at the U.S. Fish and Wildlife Service's Northeast Fishery Center in Lamar, Pennsylvania, checks the flow rate of water leaving a phosphorus filter column. The USGS has pioneered a new use for acid mine drainage residuals that are currently a disposal challenge, usi...

  3. Drug Filtering

    NSDL National Science Digital Library

    Lawrence F. Iles

    2010-01-01

    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.

  4. The optimization of essential oils supercritical CO2 extraction from Lavandula hybrida through static-dynamic steps procedure and semi-continuous technique using response surface method

    PubMed Central

    Kamali, Hossein; Aminimoghadamfarouj, Noushin; Golmakani, Ebrahim; Nematollahi, Alireza

    2015-01-01

    Aim: The aim of this study was to examine and evaluate crucial variables in essential oils extraction process from Lavandula hybrida through static-dynamic and semi-continuous techniques using response surface method. Materials and Methods: Essential oil components were extracted from Lavandula hybrida (Lavandin) flowers using supercritical carbon dioxide via static-dynamic steps (SDS) procedure, and semi-continuous (SC) technique. Results: Using response surface method the optimum extraction yield (4.768%) was obtained via SDS at 108.7 bar, 48.5°C, 120 min (static: 8×15), 24 min (dynamic: 8×3 min) in contrast to the 4.620% extraction yield for the SC at 111.6 bar, 49.2°C, 14 min (static), 121.1 min (dynamic). Conclusion: The results indicated that a substantial reduction (81.56%) solvent usage (kg CO2/g oil) is observed in the SDS method versus the conventional SC method. PMID:25598636

  5. Speed adaptation as Kalman filtering

    Microsoft Academic Search

    Jose F. Barraza; Norberto M. Grzywacz

    2008-01-01

    If the purpose of adaptation is to fit sensory systems to different environments, it may implement an opti- mization of the system. What the optimum is depends on the statistics of these environments. Therefore, the system should update its parameters as the environment changes. A Kalman-filtering strategy per- forms such an update optimally by combining current estimations of the environment

  6. Comparison of adaptive lattice filters to LMS transversal filters for sinusoidal cancellation

    Microsoft Academic Search

    Richard C. North; J. R. Zeidler; T. R. Albert; W. H. Ku

    1992-01-01

    The authors compare the performance of the recursive least squares lattice (RLSL) and the normalized step-size stochastic gradient lattice (SGL) algorithms to that of the least mean square (LMS) transversal algorithm for the cancellation of sinusoidal interference. It is found that adaptive lattice filters possess a number of advantages over the LMS transversal filter, making them the preferred adaptive noise

  7. Analysis and optimized design of a distributed multi-stage EMC filter for an interleaved three-phase PWM-rectifier system for aircraft applications

    Microsoft Academic Search

    Nico Hensgens; Marcelo Silva; Jesus A. Oliver; Pedro Alou; Oscar Garcia; Jose A. Cobos

    2012-01-01

    Different possible input filter configurations for a modular three-phase PWM rectifier system consisting of three interleaved converter cells are studied. The system is designed for an aircraft application where MIL-STD-461E conducted EMI standards have to be met and system weight is a critical design issue. The importance of a LISN model on the simulated noise levels and the effect of

  8. On stochastic approximation and an adaptive Kalman filter

    Microsoft Academic Search

    Leuis L. Scharf; Daniel L. Alspach

    1972-01-01

    The orthogonality between the innovations process and the one-step predicted state of a discrete-time Kalman filter is used to specify a stochastic approximation algorithm for simple, adaptive Kalman filtering. The filter is adaptive in the sense that on-line filter signals are used to train the gain matrix to its correct, steady-state form. The problem considered is one of training the

  9. Solution of two-dimensional electromagnetic scattering problem by FDTD with optimal step size, based on a semi-norm analysis

    NASA Astrophysics Data System (ADS)

    Monsefi, Farid; Carlsson, Linus; Ran?i?, Milica; Otterskog, Magnus; Silvestrov, Sergei

    2014-12-01

    To solve the electromagnetic scattering problem in two dimensions, the Finite Difference Time Domain (FDTD) method is used. The order of convergence of the FDTD algorithm, solving the two-dimensional Maxwell's curl equations, is estimated in two different computer implementations: with and without an obstacle in the numerical domain of the FDTD scheme. This constitutes an electromagnetic scattering problem where a lumped sinusoidal current source, as a source of electromagnetic radiation, is included inside the boundary. Confined within the boundary, a specific kind of Absorbing Boundary Condition (ABC) is chosen and the outside of the boundary is in form of a Perfect Electric Conducting (PEC) surface. Inserted in the computer implementation, a semi-norm has been applied to compare different step sizes in the FDTD scheme. First, the domain of the problem is chosen to be the free-space without any obstacles. In the second part of the computer implementations, a PEC surface is included as the obstacle. The numerical instability of the algorithms can be rather easily avoided with respect to the Courant stability condition, which is frequently used in applying the general FDTD algorithm.

  10. Application of the implicit particle filter to a model of nearshore circulation

    NASA Astrophysics Data System (ADS)

    Miller, R. N.; Ehret, L. L.

    2014-04-01

    The implicit particle filter is applied to a stochastically forced shallow water model of nearshore flow, and found to produce reliable state estimates with tens of particles. The state vector of this model consists of a height anomaly and two horizontal velocity components at each point on a 128 × 98 regular rectangular grid, making for a state dimension O(104). The particle filter was applied to the model with two parameter choices representing two distinct dynamical regimes, and performed well in both. Demands on computing resources were manageable. Simulations with as many as a hundred particles ran overnight on a modestly configured workstation. In this case of observations defined by a linear function of the state vector, taken every time step of the numerical model, the implicit particle filter is equivalent to the optimal importance filter, i.e., at each step any given particle is drawn from the density of the system conditioned jointly upon observations and the state of that particle at the previous time. Even in this ideal case, the sample occasionally collapses to a single particle, and resampling is necessary. In those cases, the sample rapidly reinflates, and the analysis never loses track. In both dynamical regimes, the ensembles of particles deviated significantly from normality.

  11. 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.

  12. Imaging task-based optimal kV and mA selection for CT radiation dose reduction: from filtered backprojection (FBP) to statistical model based iterative reconstruction (MBIR)

    NASA Astrophysics Data System (ADS)

    Li, Ke; Gomez-Cardona, Daniel; Lubner, Meghan G.; Pickhardt, Perry J.; Chen, Guang-Hong

    2015-03-01

    Optimal selections of tube potential (kV) and tube current (mA) are essential in maximizing the diagnostic potential of a given CT technology while minimizing radiation dose. The use of a lower tube potential may improve image contrast, but may also require a significantly higher tube current to compensate for the rapid decrease of tube output at lower tube potentials. Therefore, the selection of kV and mA should take those kinds of constraints as well as the specific diagnostic imaging task in to consideration. For conventional quasi-linear CT systems employing linear filtered back-projection (FBP) image reconstruction algorithm, the optimization of kV-mA combinations are relatively straightforward, as neither spatial resolution nor noise texture has significant dependence on kV and mA settings. In these cases, zero-frequency analysis such as contrast-to-noise ratio (CNR) or normalized CNR by dose (CNRD) can be used for optimal kV-mA selection. The recently introduced statistical model-based iterative reconstruction (MBIR) method, however, has introduced new challenges to optimal kV and mA selection, as both spatial resolution and noise texture become closely correlated with kV and mA. In this work, a task-based approach based on modern signal detection theory and the corresponding frequency-dependent analysis has been proposed to perform the kV and mA optimization for both FBP and MBIR. By performing exhaustive measurements of task-based detectability index through the technically accessible kV-mA parameter space, iso-detectability contours were generated and overlaid on top of iso-dose contours, from which the kV-mA pair that minimize dose yet still achieving the desired detectability level can be identified.

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

    NASA Astrophysics Data System (ADS)

    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

    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.

  14. A new image denoising framework based on bilateral filter

    Microsoft Academic Search

    Ming Zhang; Bahadir K. Gunturk

    2008-01-01

    The bilateral filter is a nonlinear filter that does spatial averaging without smoothing edges; it has shown to be an effective image denoising technique in addition to some other applications. There are two main contributions of this paper. First, we provide an empirical study of the optimal parameter selection for the bilateral filter in image denoising applications. Second, we present

  15. Robust Extended Kalman Filtering for Nonlinear Systems With Stochastic Uncertainties

    Microsoft Academic Search

    Kai Xiong; Chunling Wei; Liangdong Liu

    2010-01-01

    In this correspondence paper, a novel robust extended Kalman filter (REKF) for discrete-time nonlinear systems with stochastic uncertainties is proposed. The filter is derived to guarantee an optimized upper bound on the state estimation error covariance despite the model uncertainties as well as the linearization errors. Further analysis shows that the proposed filter has robustness against process noises, measurement noises,

  16. Homomorphic detection of convolved signals using class 1 filters

    Microsoft Academic Search

    Cluade S. Lindquist; Steven W. Cox

    1991-01-01

    It is shown that signals which are convolutionally combined can be detected using optimal homomorphic filtering. The system uses Fourier transforms combined with a log[ ] operator. Dual-channel filtering is described. Single-channel filtering is also possible but does not perform as well. A simulation is presented to demonstrate the computations involved. Although Class 1 algorithms were used for simplicity, the

  17. An analytical formula for the design of quadrature mirror filters

    Microsoft Academic Search

    GIANCARLO PIRANI; VALERIO ZINGARELLI

    1984-01-01

    Quadrature mirror filters have an outstanding relevance in the implementation of filter banks for dividing the speech signal into frequency bands and for reconstructing it from these subbands. An analytical formula is given, which allows one to optimize the design of the basic low-pass FIR filter by means of a straight nonlinear minimization procedure.

  18. Mechanical characteristics of filter structures for MEMS adaptive infrared detectors

    NASA Astrophysics Data System (ADS)

    Huang, H.; Liu, S.; Dell, J. M.; Faraone, L.

    2007-12-01

    This paper reports the mechanical design and optimization of tunable Fabry-Perot (FP) filter structures for the development of MEMS adaptive infrared detectors using finite element modeling and experimental investigations. The results indicate that the mechanical characteristics of the FP filters are significantly influenced by the structural designs, which eventually affect the filter performance and device integrity.

  19. Minimum Timing Jitter in Timing Recovery Based on Pre-filtered Square-Law Timing Detection

    Microsoft Academic Search

    Arnaldo Spalvieri; Maurizio Magarini

    2009-01-01

    New results about the pre-filter and the post-filter in timing recovery based on square-law detection are presented. Specifically, in the paper a matched-filter-type condition that guarantees optimality of the pre-filter against channel noise is derived. This condition can be satisfied together with the known condition for self-noise elimination, thus achieving optimality against self-noise and against channel noise simultaneously. The post-filter

  20. Optimization of the activation and nucleation steps in the precipitation of a calcium phosphate primer layer on electrospun poly(?-caprolactone).

    PubMed

    Luickx, Nathalie; Van den Vreken, Natasja; D'Oosterlinck, Willem; Van der Schueren, Lien; Declercq, Heidi; De Clerck, Karen; Cornelissen, Maria; Verbeeck, Ronald

    2015-02-01

    The present study aimed to optimize the procedure for coating electrospun poly(?-caprolactone) (PCL) fibers with a calcium phosphate (CP) layer in order to improve their potential as bone tissue engineering scaffold. In particular, attention was paid to the reproducibility of the procedure, the morphology of the coating, and the preservation of the porous structure of the scaffold. Ethanol dipping followed by an ultrasonic assisted hydrolysis of the fiber surface with sodium hydroxide solution efficiently activated the surface. The resulting reactive groups served as nucleation points for CP precipitation, induced by alternate dipping of the samples in calcium and phosphate rich solutions. By controlling the deposition, a reproducible thin layer of CP was grown onto the fiber surface. The deposited CP was identified as calcium-deficient apatite (CDHAp). Analysis of the cell viability, adhesion, and proliferation of MC3T3-E1 cells on untreated and CDHAp coated PCL scaffolds showed that the CDHAp coating enhanced the cell response, as the number of attached cells was higher in comparison to the untreated PCL and cells on the CDHAp coated samples showed similar morphologies as the ones found in the positive control. PMID:24733786

  1. IR filters for TPV converter modules

    NASA Astrophysics Data System (ADS)

    Horne, W. E.; Morgan, M. D.; Sundaram, V. S.

    1996-03-01

    This paper presents a TPV converter module for use with radioisotope heat sources such as the Department of Energy's General Purpose Heat Source (GPHS). The converter module utilizes an IR bandpass filter which transmits a band of energy at the optimum frequency for GaSb photovoltaic conversion and rejects long wavelength out of band energy with a broadband reflectance of greater than 98%. Recent progress in optimizing IR bandpass filters and photovoltaic cells for use in the TPV module is summarized. Measured data on the transmittance and reflectance of the filters, quantum efficiency of the PV cells both with and without the filters are presented. The results of using these measured results in an experimentally confirmed analytical model of the TPV converter module to calculate the performance of the optimized components are discussed. An economical pilot process for filter production is also described.

  2. Optical ranked-order filtering using threshold decomposition

    DOEpatents

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

    1987-10-09

    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.

  3. Optical ranked-order filtering using threshold decomposition

    DOEpatents

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

    1990-01-01

    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.

  4. Quantum neural network-based EEG filtering for a brain-computer interface.

    PubMed

    Gandhi, Vaibhav; Prasad, Girijesh; Coyle, Damien; Behera, Laxmidhar; McGinnity, Thomas Martin

    2014-02-01

    A novel neural information processing architecture inspired by quantum mechanics and incorporating the well-known Schrodinger wave equation is proposed in this paper. The proposed architecture referred to as recurrent quantum neural network (RQNN) can characterize a nonstationary stochastic signal as time-varying wave packets. A robust unsupervised learning algorithm enables the RQNN to effectively capture the statistical behavior of the input signal and facilitates the estimation of signal embedded in noise with unknown characteristics. The results from a number of benchmark tests show that simple signals such as dc, staircase dc, and sinusoidal signals embedded within high noise can be accurately filtered and particle swarm optimization can be employed to select model parameters. The RQNN filtering procedure is applied in a two-class motor imagery-based brain-computer interface where the objective was to filter electroencephalogram (EEG) signals before feature extraction and classification to increase signal separability. A two-step inner-outer fivefold cross-validation approach is utilized to select the algorithm parameters subject-specifically for nine subjects. It is shown that the subject-specific RQNN EEG filtering significantly improves brain-computer interface performance compared to using only the raw EEG or Savitzky-Golay filtered EEG across multiple sessions. PMID:24807028

  5. On a Primal-Dual Interior Point Filter Method

    Microsoft Academic Search

    M. Fernanda P. Costa; Edite M. G. P. Fernandes

    2011-01-01

    Here we present a primal-dual interior point method that relies on a filter line search method to promote global convergence of nonlinear optimization problems. Each entry in the filter includes two components directly taken from the first-order optimality conditions of the problem. Primal feasibility, complementarity and dual feasibility measures are used to compose the components. The logarithmic barrier function is

  6. Multichannel filtering for optimum noise reduction in microphone arrays

    Microsoft Academic Search

    Dinei A. Florêncio; Henrique S. Malvar

    2001-01-01

    Introduces an optimization criterion for the design of microphone arrays, and derives an optimum filter based on this criterion. The algorithm computes two separate correlation matrices for the signal: one for when only background noise is present, and one for when both noise and signal are present. A filter is then computed based on these matrices, optimizing the proposed weighted

  7. Ceramic filters

    SciTech Connect

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

    1995-12-31

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

  8. ADVANCED HOT GAS FILTER DEVELOPMENT

    SciTech Connect

    E.S. Connolly; G.D. Forsythe

    2000-09-30

    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.

  9. On The Design of Mismatched Filters With An Adjustable Matched Filtering Loss

    E-print Network

    Candan, Cagatay

    and to optimize the receivers of the pulse diversity systems. Index Terms--Mismatched filter, integrated side Middle East Technical University (METU) Department of Electrical and Electronics Engineering Ankara the interference from unwanted targets (point target or clutter) under the constraint of matched filtering loss

  10. Evidence-based used, yet still controversial: the arterial filter.

    PubMed

    De Somer, Filip

    2012-03-01

    Arterial line filters are considered by many as an essential safety measure inside a cardiopulmonary bypass circuit. There is no doubt that this was true during the bubble oxygenator era, but we can question whether the existing arterial line filter design and positioning of the filter are still optimal seeing the tremendous progress in cardiopulmonary bypass circuit components. This overview gives a critical overview of existing arterial line filter design. PMID:22730869

  11. Compact integrated silica wavelength filters

    Microsoft Academic Search

    Christopher N. Morgan; Siyuan Yu; Richard V. Penty; Ian H. White

    2002-01-01

    The realization of compact low-loss wavelength filters using two-dimensional integrated optics (2DIO) in a silica-on-silica material system is reported. Two designs suitable for data-communications applications are reported: a 4 × 4 channel 6.4-nm channel wavelength spacing device and an 8 × 8 channel 3.2-nm channel wavelength spacing device. The devices are fabricated in one deep etch step, and after cleaving

  12. Improved Wavelet Denoising via Empirical Wiener Filtering

    Microsoft Academic Search

    Sandeep P. Ghael; Akbar M. Sayeed

    1997-01-01

    Wavelet shrinkage is a signal estimation technique that exploits the remarkable abilities of the wavelet transformfor signal compression. Wavelet shrinkage using thresholding is asymptotically optimal in a minimax mean-squareerror (MSE) sense over a variety of smoothness spaces. However, for any given signal, the MSE-optimal processingis achieved by the Wiener filter, which delivers substantially improved performance. In this paper, we develop

  13. Feasibility of nanofluid-based optical filters.

    PubMed

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

    2013-03-01

    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

  14. 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)

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

    2013-05-01

    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.

  15. Global Stochastic Optimization for Robust and

    E-print Network

    Gall, Juergen

    technique exhibits both the robustness of filtering strategies and a remarkable accuracy. We apply. It comprises a quantitative error analysis comparing the approach with local optimization, particle filtering, and a heuristic based on particle filtering. Keywords Human Motion Capture, Stochastic Optimization, Particle

  16. The use of filter media to determine filter cleanliness

    NASA Astrophysics Data System (ADS)

    Van Staden, S. J.; Haarhoff, J.

    It is general believed that a sand filter starts its life with new, perfectly clean media, which becomes gradually clogged with each filtration cycle, eventually getting to a point where either head loss or filtrate quality starts to deteriorate. At this point the backwash cycle is initiated and, through the combined action of air and water, returns the media to its original perfectly clean state. Reality, however, dictates otherwise. Many treatment plants visited a decade or more after commissioning are found to have unacceptably dirty filter sand and backwash systems incapable of returning the filter media to a desired state of cleanliness. In some cases, these problems are common ones encountered in filtration plants but many reasons for media deterioration remain elusive, falling outside of these common problems. The South African conditions of highly eutrophic surface waters at high temperatures, however, exacerbate the problems with dirty filter media. Such conditions often lead to the formation of biofilm in the filter media, which is shown to inhibit the effective backwashing of sand and carbon filters. A systematic investigation into filter media cleanliness was therefore started in 2002, ending in 2005, at the University of Johannesburg (the then Rand Afrikaans University). This involved media from eight South African Water Treatment Plants, varying between sand and sand-anthracite combinations and raw water types from eutrophic through turbid to low-turbidity waters. Five states of cleanliness and four fractions of specific deposit were identified relating to in situ washing, column washing, cylinder inversion and acid-immersion techniques. These were measured and the results compared to acceptable limits for specific deposit, as determined in previous studies, though expressed in kg/m 3. These values were used to determine the state of the filters. In order to gain greater insight into the composition of the specific deposits stripped from the media, a four-point characterisation step was introduced for the resultant suspensions based on acid-solubility and volatility. Results showed that a reasonably effective backwash removed a median specific deposit of 0.89 kg/m 3. Further washing in a laboratory column removed a median specific deposit of 1.34 kg/m 3. Media subjected to a standardised cylinder inversion procedure removed a median specific deposit of 2.41 kg/m 3. Immersion in a strong acid removed a median specific deposit of 35.2 kg/m 3. The four-point characterisation step showed that the soluble-volatile fraction was consistently small in relation to the other fractions. The organic fraction was quite high at the RG treatment plant and the soluble-non-volatile fraction was particularly high at the BK treatment plant.

  17. Step-by-step quantitative analysis of focal adhesions

    PubMed Central

    Horzum, Utku; Ozdil, Berrin; Pesen-Okvur, Devrim

    2014-01-01

    Focal adhesions (FAs) are specialized adhesive structures which serve as cellular communication units between cells and the surrounding extracellular matrix. FAs are involved in signal transduction and actin cytoskeleton organization. FAs mediate cell adhesion, which is a critical phenomenon in cancer research. Since cells can form many and micrometer scale FAs, their quantitative analysis demands well-optimized image analysis approaches [1–3]. Here, we have optimized the analysis of FAs of MDA-MB-231 breast cancer cells. The optimization is based on proper processing of immunofluorescence images of vinculin, which is one of the markers of FAs. All image processing steps are carried out using the ImageJ software, which is freely available and in the public domain. The advantages of our method are:•The analysis steps are simplified by combining different plugins of the ImageJ program.•FAs are better detected with minimal false negatives due to optimized processing of fluorescent images.•This approach can be applied to quantify a variety of fluorescent images comprising focal and/or localized signals within a high background such as FAs, one of the many complex signaling structures in a cell.

  18. Inverse Filter Design Using Minimax Approximation Techniques for 3-D Audio

    Microsoft Academic Search

    H. I. K. Rao; V. John Mathews; Young-Cheol Park

    2006-01-01

    This paper presents a novel approach for implementing immersive audio rendering filters for a single listener using loudspeakers. We address the problem of crosstalk cancellation inherent in loudspeaker rendering and propose to implement the crosstalk cancellation filters using minimax finite impulse response (FIR) filters. The formulation is based on the Atal-Schroeder crosstalk canceller. The use of the optimal FIR filter

  19. Adaptive reduced-rank processing based on joint and iterative interpolation, decimation, and filtering

    Microsoft Academic Search

    Rodrigo C. de Lamare; Raimundo Sampaio-Neto

    2009-01-01

    We present an adaptive reduced-rank signal processing technique for performing dimensionality reduction in general adaptive filtering problems. The proposed method is based on the concept of joint and iterative interpolation, decimation and filtering. We describe an iterative least squares (LS) procedure to jointly optimize the interpolation, decimation and filtering tasks for reduced-rank adaptive filtering. In order to design the decimation

  20. 2 step/multi step equations

    NSDL National Science Digital Library

    Mr. Elmer

    2010-10-27

    There is practice modeling 2 step and multi-step equations with manipulatives. There is also a couple of videos demonstrating 2 step equations. There is a great resource at Illuminations.nctm.org 2 step equation model There are questions, instructions, and extensions to the lesson. Either show the given worksheet (PDF) or pass it out. Read the opening paragraph and discuss the situation. Ask why Mr. Roberts wouldn't want to open the crates. Follow the directions, showing the inverse operations on ...

  1. Adaptive particle filtering

    NASA Astrophysics Data System (ADS)

    Stevens, Mark R.; Gutchess, Dan; Checka, Neal; Snorrason, Magnús

    2006-05-01

    Image exploitation algorithms for Intelligence, Surveillance and Reconnaissance (ISR) and weapon systems are extremely sensitive to differences between the operating conditions (OCs) under which they are trained and the extended operating conditions (EOCs) in which the fielded algorithms are tested. As an example, terrain type is an important OC for the problem of tracking hostile vehicles from an airborne camera. A system designed to track cars driving on highways and on major city streets would probably not do well in the EOC of parking lots because of the very different dynamics. In this paper, we present a system we call ALPS for Adaptive Learning in Particle Systems. ALPS takes as input a sequence of video images and produces labeled tracks. The system detects moving targets and tracks those targets across multiple frames using a multiple hypothesis tracker (MHT) tightly coupled with a particle filter. This tracker exploits the strengths of traditional MHT based tracking algorithms by directly incorporating tree-based hypothesis considerations into the particle filter update and resampling steps. We demonstrate results in a parking lot domain tracking objects through occlusions and object interactions.

  2. FACTORING WAVELET TRANSFORMS INTO LIFTING STEPS INGRID DAUBECHIES y AND WIM SWELDENS

    E-print Network

    Guerrini, Carla

    FACTORING WAVELET TRANSFORMS INTO LIFTING STEPS INGRID DAUBECHIES y AND WIM SWELDENS #3; September discrete wavelet transform or two band subband filtering with finite filters can be decomposed of the wavelet or subband filters into elementary matrices. That such a factorization is possible is well

  3. A Filtering Method For Gravitationally Stratified Flows

    SciTech Connect

    Gatti-Bono, Caroline; Colella, Phillip

    2005-04-25

    Gravity waves arise in gravitationally stratified compressible flows at low Mach and Froude numbers. These waves can have a negligible influence on the overall dynamics of the fluid but, for numerical methods where the acoustic waves are treated implicitly, they impose a significant restriction on the time step. A way to alleviate this restriction is to filter out the modes corresponding to the fastest gravity waves so that a larger time step can be used. This paper presents a filtering strategy of the fully compressible equations based on normal mode analysis that is used throughout the simulation to compute the fast dynamics and that is able to damp only fast gravity modes.

  4. Stepping motor controller

    DOEpatents

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

    1984-01-01

    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.

  5. Laboratory comparison of continuous vs. binary phase-mostly filters

    NASA Technical Reports Server (NTRS)

    Monroe, Stanley E., Jr.; Knopp, Jerome; Juday, Richard D.

    1989-01-01

    Recent developments in spatial light modulators have led to devices which are capable of continuous phase modulation, even if only over a limited range. One of these devices, the deformable mirror device is used, to compare the relative merits of binary and partially-continuous phase filters in a specific problem of pattern recognition by optical correlation. Each filter was physically limited to only about a radiation of modulation. Researchers have predicted that for low input noise levels, continuous phase-only filters should have a higher absolute correlator peak output than the corresponding binary filters, as well as having a larger SNR. When continuous and binary filters were implemented on the DMD and they exhibited the same performance; an ad hoc filter optimization procedure was developed for use in the laboratory. The optimized continuous filter gave higher correlation peaks than did an independently optimized binary filter. Background behavior in the correlation plane was similar for the two filters, and thus the SNR showed the same improvement for the continuous filter. A phasor diagram analysis and computer simulation have explained part of the optimization procedure's success.

  6. Inverse Variation: Step By Step Lesson

    NSDL National Science Digital Library

    2012-01-01

    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.

  7. SU-E-I-62: Assessing Radiation Dose Reduction and CT Image Optimization Through the Measurement and Analysis of the Detector Quantum Efficiency (DQE) of CT Images Using Different Beam Hardening Filters

    SciTech Connect

    Collier, J; Aldoohan, S; Gill, K

    2014-06-01

    Purpose: Reducing patient dose while maintaining (or even improving) image quality is one of the foremost goals in CT imaging. To this end, we consider the feasibility of optimizing CT scan protocols in conjunction with the application of different beam-hardening filtrations and assess this augmentation through noise-power spectrum (NPS) and detector quantum efficiency (DQE) analysis. Methods: American College of Radiology (ACR) and Catphan phantoms (The Phantom Laboratory) were scanned with a 64 slice CT scanner when additional filtration of thickness and composition (e.g., copper, nickel, tantalum, titanium, and tungsten) had been applied. A MATLAB-based code was employed to calculate the image of noise NPS. The Catphan Image Owl software suite was then used to compute the modulated transfer function (MTF) responses of the scanner. The DQE for each additional filter, including the inherent filtration, was then computed from these values. Finally, CT dose index (CTDIvol) values were obtained for each applied filtration through the use of a 100 mm pencil ionization chamber and CT dose phantom. Results: NPS, MTF, and DQE values were computed for each applied filtration and compared to the reference case of inherent beam-hardening filtration only. Results showed that the NPS values were reduced between 5 and 12% compared to inherent filtration case. Additionally, CTDIvol values were reduced between 15 and 27% depending on the composition of filtration applied. However, no noticeable changes in image contrast-to-noise ratios were noted. Conclusion: The reduction in the quanta noise section of the NPS profile found in this phantom-based study is encouraging. The reduction in both noise and dose through the application of beam-hardening filters is reflected in our phantom image quality. However, further investigation is needed to ascertain the applicability of this approach to reducing patient dose while maintaining diagnostically acceptable image qualities in a clinical setting.

  8. 2-Step IMAT and 2-Step IMRT in three dimensions

    SciTech Connect

    Bratengeier, Klaus [Klinik und Poliklinik fuer Strahlentherapie, Universitaet Wuerzburg, Josef-Schneider-Str. 11, D-97080 Wuerzburg (Germany)

    2005-12-15

    In two dimensions, 2-Step Intensity Modulated Arc Therapy (2-Step IMAT) and 2-Step Intensity Modulated Radiation Therapy (IMRT) were shown to be powerful methods for the optimization of plans with organs at risk (OAR) (partially) surrounded by a target volume (PTV). In three dimensions, some additional boundary conditions have to be considered to establish 2-Step IMAT as an optimization method. A further aim was to create rules for ad hoc adaptations of an IMRT plan to a daily changing PTV-OAR constellation. As a test model, a cylindrically symmetric PTV-OAR combination was used. The centrally placed OAR can adapt arbitrary diameters with different gap widths toward the PTV. Along the rotation axis the OAR diameter can vary, the OAR can even vanish at some axis positions, leaving a circular PTV. The width and weight of the second segment were the free parameters to optimize. The objective function f to minimize was the root of the integral of the squared difference of the dose in the target volume and a reference dose. For the problem, two local minima exist. Therefore, as a secondary criteria, the magnitude of hot and cold spots were taken into account. As a result, the solution with a larger segment width was recommended. From plane to plane for varying radii of PTV and OAR and for different gaps between them, different sets of weights and widths were optimal. Because only one weight for one segment shall be used for all planes (respectively leaf pairs), a strategy for complex three-dimensional (3-D) cases was established to choose a global weight. In a second step, a suitable segment width was chosen, minimizing f for this global weight. The concept was demonstrated in a planning study for a cylindrically symmetric example with a large range of different radii of an OAR along the patient axis. The method is discussed for some classes of tumor/organ at risk combinations. Noncylindrically symmetric cases were treated exemplarily. The product of width and weight of the additional segment as well as the integral across the segment profile was demonstrated to be an important value. This product was up to a factor of 3 larger than in the 2-D case. Even in three dimensions, the optimized 2-Step IMAT increased the homogeneity of the dose distribution in the PTV profoundly. Rules for adaptation to varying target-OAR combinations were deduced. It can be concluded that 2-Step IMAT and 2-Step IMRT are also applicable in three dimensions. In the majority of cases, weights between 0.5 and 2 will occur for the additional segment. The width-weight product of the second segment is always smaller than the normalized radius of the OAR. The width-weight product of the additional segment is strictly connected to the relevant diameter of the organ at risk and the target volume. The derived formulas can be helpful to adapt an IMRT plan to altering target shapes.

  9. Wavelet domain filtering for nuclear medicine imaging

    SciTech Connect

    Nowak, R.D. [Michigan State Univ., East Lansing, MI (United States); Baraniuk, R.G. [Rice Univ., Houston, TX (United States); Hellman, R.S. [Medical College of Wisconsin, Milwaukee, WI (United States)] [and others

    1996-12-31

    We propose a new filtering/estimation method for nuclear medicine imaging. The statistical method of cross-validation is used to design optimal wavelet domain filters for improved image estimation. The quality of the resulting images is much better than standard image estimates, in both visual and mean square error senses. Moreover, experiments have shown that, using the new estimate, we can reduce the acquisition time by a factor of two and still retain high image quality.

  10. Adaptive inverse filters for stereophonic sound reproduction

    NASA Astrophysics Data System (ADS)

    Nelson, P. A.; Hamada, H.; Elliott, S. J.

    1990-07-01

    A general theoretical basis for the design of adaptive digital filters for the equalization of the response of multichannel sound reproduction systems is described. The formulation used was a generalization of the Atal-Shroeder cross talk canceller. The use of a least square approach to the digital filter design, combined with appropriate modeling delays, allowed the effective equalization of nonminimum phase components in the transmission path. A stochastic gradient algorithm is presented which facilitates the adoption of the digital filters to the optimal solution, providing the possibility of the design of the filters 'in situ' in a given listening space. Some experimental results appear at very low frequencies if the response of the filters are an exponential form.

  11. Polychromator filter design with genetic algorithm

    NASA Astrophysics Data System (ADS)

    Oh, Seungtae; Park, Jiyoung

    2015-02-01

    In Thomson scattering (TS) diagnostics, polychromators are equipped with several optical band-pass filters which cover the spectral region where the radiation from the incident laser beam is expected to be Doppler shifted. The spectral location of the transmission band of individual filters has a strong influence on the measured electron temperature (Te) since the latter is derived from a previously computed lookup table including the spectral specifications of the filters. Here, we present the design of the set of polychromator filters through genetic algorithms (GAs). We examine the developed algorithm under two specific target conditions, and optimized filter sets covering the wavelength region longer than the wavelength of the incident laser seem to be more effective in improving the accuracy of the Te calculations provided by the diagnostic.

  12. A Branch-and-Bound Algorithm for Quadratically-Constrained Sparse Filter Design

    E-print Network

    Wei, Dennis

    This paper presents an exact algorithm for sparse filter design under a quadratic constraint on filter performance. The algorithm is based on branch-and-bound, a combinatorial optimization procedure that can either guarantee ...

  13. Projection filters for modal parameter estimate for flexible structures

    NASA Technical Reports Server (NTRS)

    Huang, Jen-Kuang; Chen, Chung-Wen

    1987-01-01

    Single-mode projection filters are developed for eigensystem parameter estimates from both analytical results and test data. Explicit formulations of these projection filters are derived using the pseudoinverse matrices of the controllability and observability matrices in general use. A global minimum optimization algorithm is developed to update the filter parameters by using interval analysis method. Modal parameters can be attracted and updated in the global sense within a specific region by passing the experimental data through the projection filters. For illustration of this method, a numerical example is shown by using a one-dimensional global optimization algorithm to estimate model frequencies and dampings.

  14. HEPA filter dissolution process

    DOEpatents

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

    1994-02-22

    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.

  15. HEPA filter dissolution process

    SciTech Connect

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

    1992-12-31

    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.

  16. ELECTRET AIR FILTERS

    Microsoft Academic Search

    Rashmi Thakur; Dipayan Das; Apurba Das

    2012-01-01

    This review summarizes the research progress made so far on electret air filters used for separation of airborne particles from complex air stream. A set of different categories of these filters are delineated and the methods of manufacturing of these filters are described. The principles and mechanisms of filtration and modeling of pressure drop by these filters are analyzed. The

  17. Recirculating electric air filter

    DOEpatents

    Bergman, Werner (Pleasanton, CA)

    1986-01-01

    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.

  18. (Mobile K'' Filter program)

    SciTech Connect

    Not Available

    1991-05-17

    This report documents progress through May 16, 1990 in the marketing of the Mobile K' filter. This air filter traps fine particulates. A total number of 167 of the filter units have been sold. An effort to increase sales by lowering the cost of the units by delivering the filters unassembled is under way. (GHH)

  19. Hepa filter dissolution process

    DOEpatents

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

    1994-01-01

    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.

  20. Collaborative Filtering Recommender Systems

    Microsoft Academic Search

    J. Ben Schafer; Dan Frankowski; Jonathan L. Herlocker; Shilad Sen

    2007-01-01

    One of the potent personalization technologies powering the adap- tive web is collaborative filtering. Collaborative filtering (CF) is the process of filtering or evaluating items through the opinions of other people. CF technol- ogy brings together the opinions of large interconnected communities on the web, supporting filtering of substantial quantities of data. In this chapter we in- troduce the core

  1. Compact wide stopband SIR filter for Radio Altimeter

    Microsoft Academic Search

    Narayan Rana

    2012-01-01

    Presented in this paper is a very wide stopband filter of reduced size, improved stop-band rejection, and good input-output return loss for Radio Altimeter applications. To improve the stopband rejection three and four different types of stepped-impedance resonators (SIRs) are used. To further improve the wideband rejection, a notch filter is kept at the output of the filter. The simulated

  2. Study of mechanically tunable superconducting microwave filter using lumped elements

    Microsoft Academic Search

    Shigeki Hontsu; Shigenobu Mine; Hiroaki Nishikawa; Masaya Nakamori; Akira Fujimaki; Masumi Inoue; Atsushi Maehara; Tomoji Kawai

    2003-01-01

    We propose a mechanically tunable superconducting microwave filter based on lumped elements composed of planar meander-line inductors (L) and inter-digital capacitors (C). As the first step, we have designed and evaluated a 3-pole Chebyshev bandpass filters with lumped elements using a circuit simulator. It is found that the center frequency, bandwidth and skirt rejection of the filter can be controlled

  3. A Modified Whiteness Test for Damage Detection Using Kalman Filter Innovations

    Microsoft Academic Search

    D. Bernal; Y. Bulut

    \\u000a Deviations from whiteness in the innovations of a Kalman filter indicate that the filter is not optimal for the given data.\\u000a Accepting that the disturbances are stationary and white lack of optimality derives from the fact that the values of some\\u000a parameters have changed between the time the filter was formulated and the present. The parameters that define the filter

  4. Maneuvering target tracking with an adaptive Kalman filter

    Microsoft Academic Search

    Murat Efe; Derek P Atherton

    1998-01-01

    This paper presents a simple yet efficient adaptive Kalman filter for tracking targets expected to perform varying turn maneuvers. The process noise covariance level of a second order Kalman filter is adjusted at each time step according to the calculated turn rate. The turning rate is estimated from the magnitude of the calculated acceleration divided by the estimated speed of

  5. A digital filter for application in robot wrist force sensor

    Microsoft Academic Search

    Zhengshi Liu; Yong Wang; Yimin Lu; Fangjian Gan; Yunjian Ge

    2004-01-01

    Aimed at dynamic behavior compensation and its realization for robot wrist force sensor, a new design method for digital filter-pole-zero matched method based on bilinear transformation is developed in this paper. The design idea and the steps of this method are given. A design example and discussion are presented to show the features of the method. A dynamic compensation filter

  6. Properties of multilayer filters

    NASA Technical Reports Server (NTRS)

    Baumeister, P. W.

    1973-01-01

    New methods were investigated of using optical interference coatings to produce bandpass filters for the spectral region 110 nm to 200 nm. The types of filter are: triple cavity metal dielectric filters; all dielectric reflection filters; and all dielectric Fabry Perot type filters. The latter two types use thorium fluoride and either cryolite films or magnesium fluoride films in the stacks. The optical properties of the thorium fluoride were also measured.

  7. Results on principal component filter banks: Colored noise suppression and existence issues

    Microsoft Academic Search

    Sony Akkarakaran; P. P. Vaidyanathan

    2001-01-01

    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

  8. CLASSIFICATION SCHEMES FOR STEP SOUNDS BASED ON GAMMATONE-FILTERS

    Microsoft Academic Search

    Robert Anni; Kamil Adilo; Hendrik Purwins; Klaus Obermayer

    In this study the classication performance of 2 machine learning methods and 2 sound representations schemes are compared, having the focus on short impact like sounds: Footsteps have been classied according to the material of the oor and the shoe type. The gammatone auditory lter bank is a spectral analyser, that converts a given signal into a multi-channel simulation of

  9. A Filter Algorithm for Nonlinear Semidefinite Programming

    E-print Network

    2006-10-26

    with a huge amount of applications in control theory, optimal design, among ... Let us just mention the fundamental approach of interior point polynomial methods ..... In what follows, Step 1 is called restoration phase and the loop between the ...

  10. Cell Hybridization by Electrofusion on Filters

    Microsoft Academic Search

    Corinne Ramos; Deborah Bonenfant; Justin Teissie

    2002-01-01

    Electric field pulses induce permeabilization and associated fusogenicity in cell membranes. Electrofusion of cells is usually performed in two steps: the first is the creation of close intercellular contacts; the second is an application of electric pulses that induces membrane fusion. Very large cell contacts can be obtained by a filter aspiration method. A cell monolayer is created by controlled

  11. Interacting Particle Filtering With Discrete Observations

    E-print Network

    Del Moral , Pierre

    in the nonlinear filtering problem (in short NLF). That is, we want to find the one step predictor conditional the two types of NLF problems covered by our work. . Case A: The state signal (X n ) n#IN is an E A crucial practical advantage of the first category of NLF problems is that it leads to a natural IPS

  12. An Improved Control Algorithm for Active Filters

    Microsoft Academic Search

    Brij N. Singh; Bhim Singh; Ambrish Chandra; Parviz Rastgoufard; Kamal Al-Haddad

    2007-01-01

    This paper proposes a new control algorithm resulting in significant advantages toward smooth control of an active filter (AF). The majority of existing feedforward control methods of the AF system result in switching notches (sharp-rising ripples) in the supply current during transitions of stepped waveshaped nonlinear load current. This is due to switching signals for the AF devices, which are

  13. Kalman Filtering Jur van den Berg

    E-print Network

    van den Berg, Jur

    ;Model · Discrete time steps, continuous state-space · (Hidden) state: xt , measurement: yt · Airplane RCCPCPK |11|11|1 |111|11|1 1 |1|11 ^^^ xyxx #12;Kalman filter summary · Model: · Algorithm: repeat of a linear dynamic process of which we obtain noisy (partial) measurements · Example: radar tracking

  14. Solving Single Step Equations

    NSDL National Science Digital Library

    Ms. Reddish

    2011-09-30

    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 ...

  15. A Step Circuit Program.

    ERIC Educational Resources Information Center

    Herman, Susan

    1995-01-01

    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,…

  16. Towards robust particle filters for high-dimensional systems

    NASA Astrophysics Data System (ADS)

    van Leeuwen, Peter Jan

    2015-04-01

    In recent years particle filters have matured and several variants are now available that are not degenerate for high-dimensional systems. Often they are based on ad-hoc combinations with Ensemble Kalman Filters. Unfortunately it is unclear what approximations are made when these hybrids are used. The proper way to derive particle filters for high-dimensional systems is exploring the freedom in the proposal density. It is well known that using an Ensemble Kalman Filter as proposal density (the so-called Weighted Ensemble Kalman Filter) does not work for high-dimensional systems. However, much better results are obtained when weak-constraint 4Dvar is used as proposal, leading to the implicit particle filter. Still this filter is degenerate when the number of independent observations is large. The Equivalent-Weights Particle Filter is a filter that works well in systems of arbitrary dimensions, but it contains a few tuning parameters that have to be chosen well to avoid biases. In this paper we discuss ways to derive more robust particle filters for high-dimensional systems. Using ideas from large-deviation theory and optimal transportation particle filters will be generated that are robust and work well in these systems. It will be shown that all successful filters can be derived from one general framework. Also, the performance of the filters will be tested on simple but high-dimensional systems, and, if time permits, on a high-dimensional highly nonlinear barotropic vorticity equation model.

  17. A superior edge preserving filter with a systematic analysis

    NASA Technical Reports Server (NTRS)

    Holladay, Kenneth W.; Rickman, Doug

    1991-01-01

    A new, adaptive, edge preserving filter for use in image processing is presented. It had superior performance when compared to other filters. Termed the contiguous K-average, it aggregates pixels by examining all pixels contiguous to an existing cluster and adding the pixel closest to the mean of the existing cluster. The process is iterated until K pixels were accumulated. Rather than simply compare the visual results of processing with this operator to other filters, some approaches were developed which allow quantitative evaluation of how well and filter performs. Particular attention is given to the standard deviation of noise within a feature and the stability of imagery under iterative processing. Demonstrations illustrate the performance of several filters to discriminate against noise and retain edges, the effect of filtering as a preprocessing step, and the utility of the contiguous K-average filter when used with remote sensing data.

  18. THE SLOAN DIGITAL SKY SURVEY STRIPE 82 IMAGING DATA: DEPTH-OPTIMIZED CO-ADDS OVER 300 deg{sup 2} IN FIVE FILTERS

    SciTech Connect

    Jiang, Linhua [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287-1504 (United States); Fan, Xiaohui; McGreer, Ian D.; Green, Richard [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Bian, Fuyan [Research School of Astronomy and Astrophysics, Australian National University, Weston Creek, ACT 2611 (Australia); Strauss, Michael A.; Buck, Zoë [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Annis, James [Center for Particle Astrophysics, Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510 (United States); Hodge, Jacqueline A. [NRAO, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Myers, Adam D. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Rafiee, Alireza [Department of Physics, Astronomy, and Geosciences, Towson University, Towson, MD 21252 (United States); Richards, Gordon [Department of Physics, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States)

    2014-07-01

    We present and release co-added images of the Sloan Digital Sky Survey (SDSS) Stripe 82. Stripe 82 covers an area of ?300 deg{sup 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? 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 deg{sup 2} 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)

  19. Multiple model cardinalized probability hypothesis density filter

    NASA Astrophysics Data System (ADS)

    Georgescu, Ramona; Willett, Peter

    2011-09-01

    The Probability Hypothesis Density (PHD) filter propagates the first-moment approximation to the multi-target Bayesian posterior distribution while the Cardinalized PHD (CPHD) filter propagates both the posterior likelihood of (an unlabeled) target state and the posterior probability mass function of the number of targets. Extensions of the PHD filter to the multiple model (MM) framework have been published and were implemented either with a Sequential Monte Carlo or a Gaussian Mixture approach. In this work, we introduce the multiple model version of the more elaborate CPHD filter. We present the derivation of the prediction and update steps of the MMCPHD particularized for the case of two target motion models and proceed to show that in the case of a single model, the new MMCPHD equations reduce to the original CPHD equations.

  20. Optimization of Aperiodic Waveguide Mode Converters

    SciTech Connect

    Burke, G J; White, D A; Thompson, C A

    2004-12-09

    Previous studies by Haq, Webb and others have demonstrated the design of aperiodic waveguide structures to act as filters and mode converters. These aperiodic structures have been shown to yield high efficiency mode conversion or filtering in lengths considerably shorter than structures using gradual transitions and periodic perturbations. The design method developed by Haq and others has used mode-matching models for the irregular, stepped waveguides coupled with computer optimization to achieve the design goal using a Matlab optimization routine. Similar designs are described here, using a mode matching code written in Fortran and with optimization accomplished with the downhill simplex method with simulated annealing using an algorithm from the book Numerical Recipes in Fortran. Where Haq et al. looked mainly for waveguide shapes with relatively wide cavities, we have sought lower profile designs. It is found that lower profiles can meet the design goals and result in a structure with lower Q. In any case, there appear to be very many possible configurations for a given mode conversion goal, to the point that it is unlikely to find the same design twice. Tolerance analysis was carried out for the designs to show edge sensitivity and Monte Carlo degradation rate. The mode matching code and mode conversion designs were validated by comparison with FDTD solutions for the discontinuous waveguides.

  1. Rigid porous filter

    DOEpatents

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

    2000-01-01

    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.

  2. A blind particle filtering detector of signals transmitted over flat fading channels

    Microsoft Academic Search

    Yufei Huang; Petar M. Djuric

    2004-01-01

    A new particle filtering detector (PFD) is proposed for blind signal detection over flat Rayleigh fading channels whose model coefficients are unknown. The detector employs a hybrid importance function and a mixture Kalman filter. It also incorporates an auxiliary particle filtering strategy with a smoothing kernel in the resampling step. Further, by considering practical information of communication systems and the

  3. Photonic-crystal near-ultraviolet reflectance filters fabricated by nanoreplica molding

    E-print Network

    Cunningham, Brian

    January 2006; published online 14 February 2006 One-dimensional photonic-crystal reflectance filters-UV photonic crystals is an important step in the realization of PC-based near-UV lasers and filters usedPhotonic-crystal near-ultraviolet reflectance filters fabricated by nanoreplica molding Nikhil

  4. Advanced CSS Layouts: Step by Step

    NSDL National Science Digital Library

    King, Andy.

    Most Web sites are designed with HTML tables, which can be an arduous task. Making sites that are accessible and standards-compliant requires a separation of markup and content, and CSS is the best way to accomplish this. This Web page by Rogelio Vizcaino Lizaola and Andy King offers a step-by-step CSS layout tutorial on how to create WebReference table-like layouts (that behave well with small window sizes and large fonts), while avoiding some of the bugs and problems discovered in other implementations. Target browsers include all of the generation five and greater browsers on both Windows and Macintosh platforms.

  5. Thermal control design of the Lightning Mapper Sensor narrow-band spectral filter

    NASA Technical Reports Server (NTRS)

    Flannery, Martin R.; Potter, John; Raab, Jeff R.; Manlief, Scott K.

    1992-01-01

    The performance of the Lightning Mapper Sensor is dependent on the temperature shifts of its narrowband spectral filter. To perform over a 10 degree FOV with an 0.8 nm bandwidth, the filter must be 15 cm in diameter and mounted externally to the telescope optics. The filter thermal control required a filter design optimized for minimum bandpass shift with temperature, a thermal analysis of substrate materials for maximum temperature uniformity, and a thermal radiation analysis to determine the parameter sensitivity of the radiation shield for the filter, the filter thermal recovery time after occultation, and heater power to maintain filter performance in the earth-staring geosynchronous environment.

  6. Cordierite silicon nitride filters

    SciTech Connect

    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

    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.

  7. Filter type gas sampler with filter consolidation

    DOEpatents

    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

    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.

  8. Timing estimation for a filtered Poisson process in Gaussian noise

    Microsoft Academic Search

    Alfred O. Hero III

    1991-01-01

    The problem of estimation of time shift of an inhomogeneous casually filtered Poisson process in the presence of additive Gaussian noise is discussed. Approximate expressions for the likelihood function, the MAP estimator, and the MMSE estimator that becomes increasingly accurate as the per-unit-time density of superimposed filter responses becomes small are obtained. The optimal MAP estimator takes the form of

  9. Using LDA and Ant Colony Algorithm for Spam Mail Filtering

    Microsoft Academic Search

    Hui Yin; Fengjuan Cheng; Dexian Zhang

    2009-01-01

    Spam mails are extremely inconvenient, annoying and wasteful to most users since they waste time and bandwidth. To efficiently resolve this problem, a new spam mail filtering algorithm is proposed by using linear discriminant analysis(LDA) and ant colony optimization(ACO) algorithm. The experimental results show that this algorithm is feasible and performs much better than other typical spam filtering algorithms.

  10. Filter banks for prediction-compensated multiple description coding

    Microsoft Academic Search

    Jing Wang; Jie Liang

    2009-01-01

    In this paper, a prediction-compensated multiple description (MD) coding framework for two-band filter banks is proposed, in which the coefficients in each subband are split into two descriptions. Each description also includes the prediction residuals of the data in the other description. The designs of the optimal orthogonal and biorthogonal filter banks are formulated in a unified framework, and both

  11. Nonlinear bayesian filtering with applications to estimation and navigation 

    E-print Network

    Lee, Deok-Jin

    2005-08-29

    In principle, general approaches to optimal nonlinear filtering can be described in a unified way from the recursive Bayesian approach. The central idea to this recur- sive Bayesian estimation is to determine the probability density function...

  12. Efficient and reliable schemes for nonlinear diffusion filtering

    Microsoft Academic Search

    Joachim Weickert; Bart M. Ter Haar Romeny; Max A. Viergever

    1998-01-01

    Nonlinear diffusion filtering is usually performed with explicit schemes. They are only stable for very small time steps, which leads to poor efficiency and limits their practical use. Based on a recent discrete nonlinear diffusion scale-space framework we present semi-implicit schemes which are stable for all time steps. These novel schemes use an additive operator split- ting (AOS), which guarantees

  13. Image Restoration Based on Adaptive MCMC Particle Filter

    Microsoft Academic Search

    Hui Tian; Tingzhi Shen; Bing Hao; Yu Hu; Nan Yang

    2009-01-01

    In this paper, particle filter is applied in image restoration which can be posed as a recursive Bayesian estimation problem, in order to remove degeneracy phenomenon and alleviate the sample impoverishment problem, the convergence of Markov chain Monte Carlo (MCMC) method is introduced and used in resampling step, meanwhile a simple KLD sampling which separated from resampling step is combined

  14. Step-Optimized Particle Swarm Optimization Thomas Schoene

    E-print Network

    Ludwig, Simone

    --Recent developments of Particle Swarm Optimiza- tion (PSO) have successfully trended towards Adaptive PSO (APSO). APSO and effectively. In classical PSO, all parameters remain constant for the entire swarm during the iterations PSO (SOPSO) algorithm in which every particle has its own velocity weights and an inner PSO iteration

  15. INEEL HEPA Filter Leach System: A Mixed Waste Solution

    SciTech Connect

    Argyle, Mark Don; Demmer, Ricky Lynn; Archibald, Kip Ernest; Brewer, Ken Neal; Pierson, Kenneth Alan; Shackelford, Kimberlee Rene; Kline, Kelli Suzanne

    1999-03-01

    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.

  16. Earth Water Filter

    NSDL National Science Digital Library

    2005-12-17

    In this video segment adapted from ZOOM, cast members try to make the most effective water filter. They experiment with filtering dirty, salty water through different combinations of sand, gravel, and a cotton bandana.

  17. Artificial immune algorithm for IIR filter design

    Microsoft Academic Search

    Adem Kalinli; Nurhan Karaboga

    2005-01-01

    Over the recent years, several studies have been carried out by the researchers to describe a general, flexible and powerful design method based on modern heuristic optimisation algorithms for infinite impulse response (IIR) digital filters since these algorithms have the ability of finding global optimal solution in a nonlinear search space. One of the modern heuristic algorithms is the artificial

  18. Kalman Filter Constraint Tuning for Turbofan Engine Health Estimation

    NASA Technical Reports Server (NTRS)

    Simon, Dan; Simon, Donald L.

    2005-01-01

    Kalman filters are often used to estimate the state variables of a dynamic system. However, in the application of Kalman filters some known signal information is often either ignored or dealt with heuristically. For instance, state variable constraints are often neglected because they do not fit easily into the structure of the Kalman filter. Recently published work has shown a new method for incorporating state variable inequality constraints in the Kalman filter, which has been shown to generally improve the filter s estimation accuracy. However, the incorporation of inequality constraints poses some risk to the estimation accuracy as the Kalman filter is theoretically optimal. This paper proposes a way to tune the filter constraints so that the state estimates follow the unconstrained (theoretically optimal) filter when the confidence in the unconstrained filter is high. When confidence in the unconstrained filter is not so high, then we use our heuristic knowledge to constrain the state estimates. The confidence measure is based on the agreement of measurement residuals with their theoretical values. The algorithm is demonstrated on a linearized simulation of a turbofan engine to estimate engine health.

  19. Filter service system

    DOEpatents

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

    2008-12-09

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

  20. The Ribosome Filter Redux

    PubMed Central

    Mauro, Vincent P.; Edelman, Gerald M.

    2010-01-01

    The ribosome filter hypothesis postulates that ribosomes are not simply translation machines but also function as regulatory elements that differentially affect or filter the translation of particular mRNAs. On the basis of new information, we take the opportunity here to review the ribosome filter hypothesis, suggest specific mechanisms of action, and discuss recent examples from the literature that support it. PMID:17890902

  1. HEPA filter encapsulation

    DOEpatents

    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

    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.

  2. Aircraft Recirculation Filter for Air-Quality and Incident Assessment

    PubMed Central

    Eckels, Steven J.; Jones, Byron; Mann, Garrett; Mohan, Krishnan R.; Weisel, Clifford P.

    2015-01-01

    The current research examines the possibility of using recirculation filters from aircraft to document the nature of air-quality incidents on aircraft. These filters are highly effective at collecting solid and liquid particulates. Identification of engine oil contaminants arriving through the bleed air system on the filter was chosen as the initial focus. A two-step study was undertaken. First, a compressor/bleed air simulator was developed to simulate an engine oil leak, and samples were analyzed with gas chromatograph-mass spectrometry. These samples provided a concrete link between tricresyl phosphates and a homologous series of synthetic pentaerythritol esters from oil and contaminants found on the sample paper. The second step was to test 184 used aircraft filters with the same gas chromatograph-mass spectrometry system; of that total, 107 were standard filters, and 77 were nonstandard. Four of the standard filters had both markers for oil, with the homologous series synthetic pentaerythritol esters being the less common marker. It was also found that 90% of the filters had some detectable level of tricresyl phosphates. Of the 77 nonstandard filters, 30 had both markers for oil, a significantly higher percent than the standard filters. PMID:25641977

  3. Anti-resonance mixing filter

    NASA Technical Reports Server (NTRS)

    Evans, Paul S. (Inventor)

    2001-01-01

    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.

  4. Implementation and Evaluation of an Acoustic Echo Canceller using Duo-Filter Control System

    Microsoft Academic Search

    Yoichi Haneda; Shoji Makino; Junji Kojima; Suehiro Shimauchi

    The developed acoustic echo canceller uses an exponentially weighted step-size projection algorithm and a duo-filter control system to achieve fast convergence and high speech quality. The duo-filter control system has an adaptive filter and a fixed filter, and uses variable-loss insertion. Evaluation of this system with multi-channel A\\/D and D\\/A converters showed that (1) the convergence speed is under 1.5

  5. Design of microstrip bandpass filters with multiorder spurious-mode suppression

    Microsoft Academic Search

    Chi-Feng Chen; Ting-Yi Huang; Ruey-Beei Wu

    2005-01-01

    This paper proposes a bandpass filter design method for suppressing spurious responses in the stopband by choosing the constitutive resonators with the same fundamental frequency, but staggered higher order resonant frequencies. The design concept is demonstrated by a four-pole parallel-coupled Chebyshev bandpass filter and a compact four-pole cross-coupled elliptic-type bandpass filter. Each filter is composed of four different stepped-impedance resonators

  6. Statistically Optimal Averaging for Image Restoration and Optical Flow Estimation

    Microsoft Academic Search

    Rudolf Mester Kai Krajsek; Hanno Scharr

    2008-01-01

    In this paper we introduce a Bayesian best linear unbiased estimator (Bayesian BLUE) and apply it to generate optimal averaging filters. Linear filtering of signals is a basic operation frequently used in low level vision. In many applications, filter selection is ad hoc without proper theoretical justification. For example input signals are often convolved with Gaussian filter masks, i.e masks

  7. Nucleation at macroscopic steps

    NASA Astrophysics Data System (ADS)

    Mederos, L.; Quintana, A.; Navascués, G.

    1984-11-01

    The classical heterogeneous nucleation theory is used to study nucleation at macroscopic steps. Line tension effects are included to give a correct description of the phenomena within the known limits of the theory. A criterion of preferential nucleation at steps (decoration criterion) is given. The expected behavior of the system for low macroscopic contact angles is found.

  8. Improving Superconducting Qubit Lifetimes with Broadband Filters

    NASA Astrophysics Data System (ADS)

    Bronn, Nicholas; Corcoles, Antonio; Hertzberg, Jared; Srinivasan, Srikanth; Chow, Jerry; Gambetta, Jay; Steffen, Matthias; Liu, Yanbing; Houck, Andrew

    2015-03-01

    In circuit quantum electrodynamics, the state of the qubit is read out via a resonator at a different frequency than that of the qubit. Spontaneous qubit decay via the resonator may be suppressed by engineering an impedance mismatch at the qubit frequency, while still allowing a large coupling between the resonator and external environment necessary for fast, high fidelity readout. We present a stepped-impedance filter with a large stop-band in the qubit frequency range and demonstrate its effect on qubit lifetime. This filter is also effective when used in an off-chip geometry. We acknowledge support from IARPA under Contract W911NF-10-1-0324.

  9. Optimal Delayed Decisions in Decoding of Predictively

    E-print Network

    California at Santa Barbara, University of

    that the quantization noise is white and uncorrelated with the source Kalman filter optimal for linear Gaussian model) [Chang & Gibson, `91] Apply a non-causal post-filter to smooth the zero-delay reconstructions: non - ^n Lx +2 ^nx - ^nx + n Lb + 2nb +1nb +1nb -2nb - nb Delayed reconstructions after filtering #12

  10. STEP Experiment Requirements

    NASA Technical Reports Server (NTRS)

    Brumfield, M. L. (compiler)

    1984-01-01

    A plan to develop a space technology experiments platform (STEP) was examined. NASA Langley Research Center held a STEP Experiment Requirements Workshop on June 29 and 30 and July 1, 1983, at which experiment proposers were invited to present more detailed information on their experiment concept and requirements. A feasibility and preliminary definition study was conducted and the preliminary definition of STEP capabilities and experiment concepts and expected requirements for support services are presented. The preliminary definition of STEP capabilities based on detailed review of potential experiment requirements is investigated. Topics discussed include: Shuttle on-orbit dynamics; effects of the space environment on damping materials; erectable beam experiment; technology for development of very large solar array deployers; thermal energy management process experiment; photovoltaic concentrater pointing dynamics and plasma interactions; vibration isolation technology; flight tests of a synthetic aperture radar antenna with use of STEP.

  11. Laser radar based relative navigation using improved adaptive Huber filter

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoliang; Gong, Deren; Xu, Liqiang; Shao, Xiaowei; Duan, Dengping

    2011-06-01

    An improved adaptive Huber filter algorithm is proposed to model error and measurement noise uncertainty in this work. The adaptive algorithm for model error is obtained by using an upper bound for the state prediction covariance matrix with augment of chi-square statistical hypothesis test in case of filter deteriorated by wrong residual information. The measurement noise is estimated at each filter step by minimizing a criterion function which was original from Huber filter. A recursive algorithm is provided for solving the criterion function. The proposed adaptive filter algorithm was successfully implemented in radar navigation system for spacecraft formation flying in high earth orbits with real orbit perturbations and non-Gaussian random measurement error. Simulation results indicated that the proposed adaptive filter performed better in robustness and accuracy compared with previous adaptive algorithms.

  12. Method of producing monolithic ceramic cross-flow filter

    DOEpatents

    Larsen, David A. (Clifton Park, NY); Bacchi, David P. (Schenectady, NY); Connors, Timothy F. (Watervliet, NY); Collins, III, Edwin L. (Albany, NY)

    1998-01-01

    Ceramic filter of various configuration have been used to filter particulates from hot gases exhausted from coal-fired systems. Prior ceramic cross-flow filters have been favored over other types, but those previously horn have been assemblies of parts somehow fastened together and consequently subject often to distortion or delamination on exposure hot gas in normal use. The present new monolithic, seamless, cross-flow ceramic filters, being of one-piece construction, are not prone to such failure. Further, these new products are made by novel casting process which involves the key steps of demolding the ceramic filter green body so that none of the fragile inner walls of the filter is cracked or broken.

  13. Convex-Programming Design of Linear and Nonlinear Phase Wideband Blocking Filters

    Microsoft Academic Search

    Dan P. Scholnik

    2011-01-01

    Blocking filters are commonly used in array pro- cessing to excise targets from data when suitable target-free training data is not available. A drawback is the reduction of the effective size of the array by the order of the filter, motivating a search for the smallest filter that meets the design specifications. Common linear-phase approaches lead to convex optimization and

  14. LMS Electrical Filters to Reduce Intersymbol Interference in Direct Detection Optical Systems

    E-print Network

    Humblet, Pierre A.

    distance transmission, the fiber itself plays the role of an optical filter as it disperses the pulse is to design optimal filters from basic principles. Examples of a Fabry­Perot interferometer for optical as shown in Figure 1. The received signal after the optical filter is x(t) = # 2 Re { X k a k p(t - kT )e j

  15. An Adaptive Fuzzy Strong Tracking Kalman Filter for GPS\\/INS Navigation

    Microsoft Academic Search

    Dah-Jing Jwo; Cheng-Min Huang

    2007-01-01

    The Kalman filtering is a form of recursive optimal estimation, which has been widely applied to the navigation designs. Kalman filter requires that all the plant dynamics and noise processes are exactly known, and the noise process is zero mean white noise. If the theoretical behavior of a filter and its actual behavior do not agree, divergence problems will occur.

  16. IEEE TRANSACTIONS ON IMAGE PROCESSING -14(1), 2005 1 Conditional Filters for Image Sequence Based

    E-print Network

    Paris-Sud XI, Université de

    variance estimator, particle filtering, optimal importance func- tion, robust motion estimation. The second one is a nonlinear tracker, implemented from a conditional particle filter. It allows trackingIEEE TRANSACTIONS ON IMAGE PROCESSING - 14(1), 2005 1 Conditional Filters for Image Sequence Based

  17. Real-time hand tracking using a mean shift embedded particle filter

    Microsoft Academic Search

    Caifeng Shan; Tieniu Tan; Yucheng Wei

    2007-01-01

    Particle filtering and mean shift (MS) are two successful approaches to visual tracking. Both have their respective strengths and weaknesses. In this paper, we propose to integrate advantages of the two approaches for improved tracking. By incorporating the MS optimization into particle filtering to move particles to local peaks in the likelihood, the proposed mean shift embedded particle filter (MSEPF)

  18. Maximum Average correlation Height filter for detecting distortion targets in cluttered environment using computational intelligence

    Microsoft Academic Search

    Jiyang Shang; Xue Zhan; Wensheng Wang

    2010-01-01

    Based on the computational intelligence and the principle of matched filter, the recognition problem of distortion target (rotation and scale etc.) in cluttered background scene is solved. The Maximum Average correlation Height (MACH) algorithm is adopted to design the matched filter, and control parameters of the filter are optimized. It is a very effective way to have high tolerance and

  19. Advanced hot-gas filter development

    SciTech Connect

    Stankiewicz, E.P.; Sherman, A.J.; Zinn, A.A.

    1997-12-31

    Coal is the most abundant fossil-fuel resource in the United States. `Clean coal` technologies, such as pressurized fluidized-bed combustion (PFBC) and integrated gasification combined-cycle (IGCC), require a hot gas filter to remove the corrosive and erosive coal ash entrained in the combustion gas stream. These hot gas filters, or candle filters, must be cost-effective while able to withstand the effects of corrosion, elevated temperature, thermal shock, and temperature transients. Ash loadings may range from 500 to 10,000 ppm by weight, and may contain particles as fine as 0.008 mils. The operating environment for the hot gas filter can range in pressure from 10 to 20 atm, in temperatures from 700 to 1750{degrees}F, and can be oxidizing or reducing. In addition, the process gases may contain volatile chloride, sulfur, and alkali species. Field testing of various commercially available, porous, ceramic filter matrices has demonstrated a loss of up to 50 percent of as-manufactured strength after 1,000 to 2,000 hours of exposure to these operating conditions, although full-scale elements have remained intact during normal process operations. Ultramet, a small business specializing in advanced materials R&D, has developed a new class of hot gas filter materials that offers lower back-pressure, higher permeability, longer life, and high filtration efficiency in the PFBC and IGCC environments. Subscale Ultrafoam Duplex Filter elements have undergone accelerated corrosion testing at temperatures of up to 2370{degrees}F (at Ultramet), and have been subjected to over 2,800 hours of exposure to hot PFBC gases (in the Westinghouse Advanced Particulate Filtration System at Brilliant, OH) without any loss in strength in either case. The Ultrafoam Duplex Filter matrix demonstrated 100 percent particle- capture efficiency of coal ash, and had an initial pressure drop of 0.1 to 0.6 in-wc/fpm. The Ultrafoam Duplex Filter is composed of a chemical vapor deposition (CVD), silicon carbide (SiC), reticulated, open-cell foam filter body supporting a porous mullite membrane filter. The reticulated foam structure is 70 to 90 percent porous, enabling high permeability, while the 3-D interconnected cellular lattice resists crack propagation. The CVD SiC material is fine-grained for maximum strength and corrosion resistance, and has no binders or impurities. The porous, mullite, membrane filter is impregnated into the outer surface of the CVD SiC Ultrafoam filter element. The membrane bonds to the foam ligaments, while the foam ligaments reinforce and support the membrane. The mullite membrane, which acts as a barrier filter, is resistant to thermal shock and corrosion. The thin membrane minimizes pressure drop and thermal gradients. The composite Ultrafoam Duplex Filter was designed to combine optimal material selection with functional structural design to maximize corrosion resistance, thermal shock resistance, strength, toughness, and life while minimizing pressure drop and weight. Oxidation rate, corrosion resistance, creep strength, compressive strength, and C-ring strength of the CVD SiC Ultrafoam filter body, and pressure drop and filtration efficiency for subscale Ultrafoam Duplex Filter elements, are reported. Future work is targeted at the construction of full-scale hot gas filters, and will include further strength and accelerated corrosion testing of subscale sections of the filter body, the membrane, and the composite duplex filter elements.

  20. CMOS optoelectronic database filter: implementation and analysis

    NASA Astrophysics Data System (ADS)

    Tang, Jianjing; Pattanayak, Arunansu; Beyette, Fred R., Jr.

    2003-12-01

    Optical storage devices are being used to meet the growing demand for high capacity archival data storage. A challenging task facing the designers for the next generation of archival storage system is to provide storage capacities several orders of magnitude larger than existing systems while maintaining current data access times. To meet this challenge, we have developed a smart optoelectronic database filter suitable for large capacity relational database systems that use page-oriented optical storage devices. The photonic VLSI chip monolithically integrates a smart-pixel array that incorporates page-oriented optical reading, data manipulation logic, data buffering and filter control circuitry for interfacing the filter chip with an electronic host computer. By selectively passing only the data requested by the query operation, the database filter is able to accomplish the reduction in data rate without loss of valid data or significant delay in data access. The design, testing and performance evaluation of a 32x32-bit database filter fabricated in a 0.35-micron CMOS process is reported. In addition to demonstrating the first fully functioning database filter chip, we present a program that has been developed to simulate the filtering algorithm implemented by the hardware. Queuing theory has been used to perform the system level analysis of the database filter. It is shown that even with the limitation of finite queue capacity, a database filter chip could be controlled to work at near optimal performance where database search time is limited by the data transfer rate going into the host computer. The simulation program has been used to verify the validity of the queuing analysis.