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Solving Large Complex Problems Using a Higher-Order Basis: Parallel In-Core and Out-of-Core Integral-Equation Solvers

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IEEE ANTENNAS AND PROPAGATION MAGAZINE 2008年第4期50卷 13-30页

作者： Zhang, Yu Taylo, Mary Sarka, Tapan K. Moon, Hongsik Yuan, Mengtao Syracuse Univ Dept Elect Engn & Comp Sci Syracuse NY 13244 USA Xidian Univ Sch Elect & Engn Xian 710071 Peoples R China

The future of computational electromagnetics is changing drastically with the new generation of computer chips, which are multi-cored instead of single-cored. Previously, advancements in chip technology meant an increase in clock speed, which was typically a benefit that computational code users could enjoy. This is no longer the case. In the new roadmaps for chip manufacturers, speed has been sacrificed for improved power consumption, and the direction is multi-core processors. The burden now falls on the software programmer to revamp existing codes and add new functionality to enable computational codes to run efficiently on this new generation of multi-core processors. In this paper, a new roadmap for computational code designers is provided, demonstrating how to navigate along with the chip designers through the multi-core advancements in chip design. A new parallel code, using the Method of Moments (MoM) and higher-order functions for expansion and testing, and executed on a range of computer platforms, will illustrate this roadmap. The advantage of a higher-order basis over a subdomain basis is a reduction in the number of unknowns. This means that with the same computer resources, a larger problem can be solved using higher-order basis than using a subdomain basis. The matrix filling for MoM with subdomain basis must be programmed with multiple loops over the edges of the patches to account for the interactions. However, higher-order basis functions, such as polynomials, can be calculated more efficiently with fewer integrations, at least for the serial code. In terms of parallel integral-equation solvers, the differences between these categories of basis functions must be understood and accommodated. If computational codes are not written properly for parallel operation, taking into account the central processing unit (CPU) architecture and operating system, the result will be an extremely inefficient code. The research presented here will show how to take t

关键词： computational electromagnetics computation time moment methods electrically large objects in-core solver out-of-core solver parallel algorithms parallel architectures parallel algorithms parallel programming parallel processing radar cross section vivaldi antennas

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Hybrid algorithm to reduce the computation time of genetic algorithm for designing binary phase holograms

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OPTICAL ENGINEERING 2004年第9期43卷 2061-2065页

作者： Nguyen, TA An, JW Choi, JK Kim, N Jeon, SH Kwon, YS Chungbuk Natl Univ Chonju South Korea Univ Incheon Dept Elect Engn Inha South Korea

To reduce computation time, a new approach for designing computer-generated holograms is proposed. In this new method, we utilize artificial neural networks to initiate the genetic algorithm, so that the high computation cost of genetic algorithms for synthesizing holograms is significantly reduced, while the high diffraction efficiency and uniformity are still ensured. Designed binary phase holograms have a diffraction efficiency of 75.8% and uniformity of 5.8%, which are proven in computer simulation and experimentally demonstrated. (C) 2004 Society or Photo-optical Instrumentation Engineers.

关键词： computer-generated holograms genetic algorithm artificial neural network computation time

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Fast evaluation of the radiation patterns of true time delay arrays with beam steering

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IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION 2007年第12期55卷 3421-3432页

作者： Shlivinski, Amir Boag, Amir Ben Gurion Univ Negev Dept Elect & Comp Engn IL-84105 Beer Sheva Israel Tel Aviv Univ Sch Elect Engn IL-69978 Tel Aviv Israel

A multilevel algorithm for the computation of the transient radiation patterns of true time delay (TTD) conformal arrays over a range of observation and beam steering directions is presented. The multilevel algorithm is based on hierarchical decomposition of the array into smaller sub-arrays of elements. At the finest level of decomposition, the angular-temporal radiation patterns of single-element sub-arrays are obtained over a sparse angular grid of directions and short temporal duration, by either measurement or calculation. Subsequent steps of the algorithm comprise multilevel aggregation of delayed sub-array contributions. This process continues until the transient radiation pattern of the whole array is obtained. At each level, the radiation pattern is interpolated to a finer angular grid of observations and steering directions followed by temporal delay compensation. The multilevel array decomposition algorithm attains a computational complexity substantially lower than that of the direct evaluation. Furthermore, the algorithm is particularly efficient for large arrays with large numbers of elements.

关键词： antenna transient analysis computation time domain decomposition time-delay arrays ultrawideband (UWB) antennas

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Ratchetting strain prediction

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INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING 2007年第4期84卷 223-233页

作者： Noban, Mohammad Jahed, Hamid Iran Univ Sci & Technol Mech Engn Dept Tehran 16844 Iran Univ Waterloo Dept Mech & Mechatron Engn Waterloo ON N21 3G1 Canada

A time-efficient method for predicting ratchetting strain is proposed. The ratchetting strain at any cycle is determined by finding the ratchetting rate at only a few cycles. This determination is done by first defining the trajectory of the origin of stress in the deviatoric stress space and then incorporating this moving origin into a cyclic plasticity model. It is shown that at the beginning of the loading, the starting point of this trajectory coincides with the initial stress origin and approaches the mean stress, displaying a power-law relationship with the number of loading cycles. The method of obtaining this trajectory from a standard uniaxial asymmetric cyclic loading is presented. Ratchetting rates are calculated with the help of this trajectory and through the use of a constitutive cyclic plasticity model which incorporates deviatoric stresses and back stresses that are measured with respect to this moving frame. The proposed model is used to predict the ratchetting strain of two types of steels under single- and multi-step loadings. Results obtained agree well with the available experimental measurements. (C) 2006 Elsevier Ltd. All rights reserved.

关键词： cyclic plasticity ratchetting multi-step loading computation time

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The algorithm of fast mean filtering

The algorithm of fast mean filtering

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5th International Conference on Wavelet Analysis and Pattern Recognition

作者： Pan, Jian-Jia Tang, Yuan-Yan Pan, Bao-Chang Hong Kong Baptist Univ Dept Comp Sci Kowloon Hong Kong Peoples R China Guandong Univ Technol Fac Informat Engn Guangzhou 510000 Peoples R China

ISBN: (纸本)9781424410651

Mean filtering is a normal filtering method. It simply smoothes local variations in an image, and noise is reduced as a result of blurring. But it takes many times to compute the neighborhood pixels. An algorithm of Fast Mean Filtering (FMF) is presented in this paper. The processing speed of the FMF is much faster than the traditional mean filtering, and the filtering result is the same as the traditional mean filtering.

关键词： mean filter Fast Mean Filtering computation time

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The mathworks distributed and parallel computing tools for signal processing applications

The mathworks distributed and parallel computing tools for s...

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32nd IEEE International Conference on Acoustics, Speech and Signal Processing

作者： Behboodian, Ali Grad-Freilich, Silvina Martin, Grant MathWorks Inc 3 Apple Hill Dr Natick MA 01760 USA

ISBN: (纸本)1424407281

As requirements for technical computing applications become more complex, engineers and scientists must solve problems of increasing computational intensity that frequently outstrip the capability of their own computers. Some are distributed applications (also called coarse-grained or embarrassingly parallel applications), where the same algorithm is independently executed over and over on different input parameters. Others consist of parallel (or fine-grained) applications, which contain interdependent tasks that exchange data during the execution of the application. This article introduces the distributed and parallel computing capabilities in The MathWorks distributed computing tools and provides examples of how these capabilities are applied to signal processing applications.

关键词： distributed algorithms parallel processing computation time distributed computing

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A comparison of GAs using penalizing infeasible solutions and repairing infeasible solutions on average capacity knapsack

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2nd International Symposium on Intelligence computation and Application (ISICA 2007)

作者： He, Jun Zhou, Yuren Univ Birmingham Sch Comp Sci CERCIA Birmingham B15 2TT W Midlands England South China Univ Technol Guangzhou Guangdong Peoples R China

ISBN: (纸本)9783540745808

Different constraint handling techniques have been incorporated with genetic algorithms (CAs), however most of current studies are based on computer experiments. The paper makes an theoretical analysis of GAs using penalizing infeasible solutions and repairing infeasible solutions on average knapsack problem. It is shown that GAs using the repair method is more efficient than GAs using the penalty method on average capacity knapsack problems.

关键词： genetic algorithms constrained optimization knapsack problem computation time performance analysis

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Adaptive-mesh-based algorithm for fluorescence molecular tomography using an analytical solution (vol 15, pg 9722, 2007)

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OPTICS EXPRESS 2007年第17期15卷 10789-10789页

作者： Wang, Daifa Song, Xiaolei Bai, Jing Tsing Hua Univ Dept Biomed Engn Beijing 100084 Peoples R China

关键词： .fluorescent computation time image quality reconstructions approximation Adaptive mesh Molecular Imaging refinement analytical solution solution of diffusion Weissleder and Ntziachristos

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A computation time optimization for the radio coverage prediction

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ANNALES DES TELECOMMUNICATIONS-ANNALS OF TELECOMMUNICATIONS 2003年第7-8期58卷 1130-1156页

作者： Combeau, P Vauzelle, R Aveneau, L Pousset, Y Univ Poitiers IRCOM SIC UMR 6615 CNRS F-86962 Futuroscope France

This article presents a method which optimises the computation time for the prediction of a radio coverage, whatever the propagation model used. The principle consists in reducing the number of application points of the propagation model in relation to a classical technique. The proposed method is based on a multi resolution analysis of measured signals carried out around 2 GHz, and on an electromagnetic analysis of the propagation environment. The performances of the method are evaluated in term of reduction in computation time and of accuracy, in comparaison with the classical technique.

关键词： mobile radiocommunication transmitter coverage electromagnetic wave propagation radio wave multipath propagation wave reflection wave diffraction computation time wavelet expansion optimization partition

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Mapping quantitative trait loci by an extension of the Haley-Knott regression method using estimating equations

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GENETICS 2006年第4期173卷 2269-2282页

作者： Feenstra, Bjarke Skovgaard, Ib M. Broman, Karl W. Royal Vet & Agr Univ Dept Nat Sci DK-1871 Frederiksberg C Denmark Johns Hopkins Univ Dept Biostat Baltimore MD 21205 USA

The Haley-Knott (HK) regression method continues to be a popular approximation to standard interval mapping (IM) of quantitative trait loci (QTL) in experimental crosses. The HK method is favored for its dramatic reduction in computation time compared to the IM method, something that is particularly important in simultaneous searches for multiple interacting QTL. While the HK method often approximates the IM method well in estimating QTL effects and in power to detect QTL, it may perform poorly if, for example, there is strong epistasis between QTL or if QTL are linked. Also, it is well known that the estimation of the residual variance by the HK method is biased. Here, we present an extension of the HK method that uses estimating equations based on both means and variances. For normally distributed phenotypes this estimating equation (EE) method is more efficient than the HK method. Furthermore, computer simulations show that the EE method performs well for very different genetic models and data set structures, including nonnormal phenotype distributions, nonrandom missing data patterns, varying degrees of epistasis, and varying degrees of linkage between QTL. The EE method retains key qualities of the HK method such as computational speed and robustness against nonnormal phenotype distributions, while approximating the IM method better in terms of accuracy and precision of parameter estimates and power to detect QTL.

关键词： .Equations TRAIT LOCI interval mapping Regression residual interacting epistasis computation time mapping quantitative Haley–Knott Using Estimating HK method IM method EE method

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