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BOUNDARY INTEGRAL FORMULAS FOR ELASTIC PLANE PROBLEM OF EXTERIOR CIRCULAR DOMAIN

Applied Mathematics and Mechanics(English Edition) 2006年第7期27卷 993-1000页

作者：董正筑李顺才余德浩 College of Science China University of Mining and Technology Xuzhou 221008Jiangsu ProvinceP.R.China Institute of Computational Mathematics and Scientific/Engineering Computing Chinese Academy of Sciences Beijing 100080 P. R. China College of Science China University of Mining and Technology Xuzhou 221008Jiangsu ProvinceP.R.China Industrial School Xuzhou Normal UniversityXuzhou 221011Jiangsu ProvinceP.R.China Institute of Computational Mathematics and Scientific/Engineering Computing Chinese Academy of Sciences Beijing 100080 P. R. China

After the stress function and the normal derivative on the boundary for the plane problem of exterior circular domain are expanded into Laurent series, comparing them with the Laurent series of the complex stress function and making use of some formulas in Fourier series and the convolutions, the boundary integral formula of the stress function is derived further. Then the stress function can be obtained directly by the integration of the stress function and its normal derivative on the boundary. Some examples are given. It shows that the boundary integral formula of the stress function is convenient to be used for solving the elastic plane problem of exterior circular domain.

关键词： elastic plane problem of exterior circular domain bi-harmonic equation Fourier series stress function boundary integral formula

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Efficiently clustering transactional data with weighted coverage density 06

Efficiently clustering transactional data with weighted cove...

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15th ACM Conference on Information and Knowledge Management, CIKM 2006

作者： Yan, Hua Chen, Keke Liu, Ling Computational Intelligence Laboratory School of Computer Science and Engineering University of Electronic Science and Tech. of China Chengdu 610054 China College of Computing Georgia Institute of Technology Atlanta GA 30280 United States

ISBN: (纸本)1595934332

It is widely recognized that developing efficient and fully automated algorithms for clustering large transactional datasets is a challenging problem. In this paper, we propose a fast, memory-efficient, and scalable clustering algorithm for analyzing transactional data. Our approach has three unique features. First, we use the concept of Weighted Coverage Density as a categorical similarity measure for efficient clustering of transactional datasets. The concept of weighted coverage density is intuitive and allows the weight of each item in a cluster to be changed dynamically according to the occurrences of items. Second, we develop two transactional data clustering specific evaluation metrics based on the concept of large transactional items and the coverage density respectively. Third, we implement the weighted coverage density clustering algorithm and the two clustering validation metrics using a fully automated transactional clustering framework, called SCALE (Sampling, Clustering structure Assessment, cLustering and domain-specific Evaluation). The SCALE framework is designed to combine the weighted coverage density measure for clustering over a sample dataset with self-configuring methods that can automatically tune the two important parameters of the clustering algorithms: (1) the candidates of the best number K of clusters;and (2) the application of two domain-specific cluster validity measures to find the best result from the set of clustering results. We have conducted experimental evaluation using both synthetic and real datasets and our results show that the weighted coverage density approach powered by the SCALE framework can efficiently generate high quality clustering results in a fully automated manner. Copyright 2006 ACM.

关键词： Clustering algorithms

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Two-step iterative methods for solving the stationary convection-diffusion equation with a small parameter at the highest derivative on a uniform grid

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computational Mathematics and Mathematical Physics 2006年第2期46卷 282-293页

作者： Bai, Z.-Z. Krukier, L.A. Martynova, T.S. State Key Laboratory of Scientific/Engineering Computing Institute of Computational Mathematics and Scientific/Engineering Computing Academy of Mathematics and Systems Science Beijing 100080 P.O. Box 2719 China Computer Center Rostov State University Rostov-on-Don 344090 pr. Stachki 200/1 bld. 2 Russian Federation

A stationary convection-diffusion problem with a small parameter multiplying the highest derivative is considered. The problem is discretized on a uniform rectangular grid by the central-difference scheme. A new class of two-step iterative methods for solving this problem is proposed and investigated. The convergence of the methods is proved, optimal iterative methods are chosen, and the rate of convergence is estimated. Numerical results are presented that show the high efficiency of the methods. © MAIK "Nauka/Interperiodica" (Russia), 2006.

关键词： Convergence Dissipative matrix Iterative methods Optimal iterative parameters Transition operator

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Type Ia supernovae

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Journal of Physics: Conference Series 2007年第1期78卷 012081-012081页

作者： Woosley, S.E. Almgren, A. Bell, J.B. Glatzmaier, G. Kasen, D. Kerstein, A.R. Ma, H. Nugent, P. Röpke, F. Sankaran, V. Zingale, M. Department of Astronomy and Astrophysics UCSC Santa Cruz CA 95064 United States Center for Computational Sciences and Engineering LBNL Berkeley CA 94720 United States Department of Earth and Planetary Sciences UCSC Santa Cruz CA 95064 United States Johns Hopkins University Space Telescope Science Institute Baltimore MD 21218 United States Combustion Research Facility Sandia National Laboratories Livermore CA 94551 United States High Performance Computing Group LBNL Berkeley CA 94720 United States Max-Planck-Institut für Astrophysik Garching 85741 Karl-Schwarzschild-Str. 1 Germany Department of Physics and Astronomy State University of New York Stony Brook NY 11794 United States

At its heart, a Type Ia supernova is a problem in turbulent nuclear combustion. There are four sub-problems, each of which has eluded solution for decades, but which can be addressed by large scale simulation. First is the ignition - where and how often the burning is ignited in the convective core of an exploding white dwarf star. The outcome is sensitive to the initial conditions near the star's center, which may be chaotic. Second is the propagation of the flame. Until near the end, the flame is an unresolvably narrow sheet moved around by instabilities and the turbulence that its own motion produces, yet how fast it moves determines the strength and brightness of the explosion. Third is whether and how the subsonic burning makes a spontaneous transition to a detonation. Observations favor this outcome, but the physics of the transition is obscure. Fourth, is the radiation transport problem. Why does the supernova look the way it does and can its light curve be relied upon to do precision cosmology? Our Consortium has made genuine progress in each of these areas, as well as in planning, with observers, future observational strategies for SNAP/JDEM and LSST. A new generation of codes is being optimized for the four tasks. © 2007 IOP Publishing Ltd.

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Aurora: An Approach to High Throughput Parallel Simulation

Aurora: An Approach to High Throughput Parallel Simulation

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Workshop on Principles of Advanced and Distributed Simulation (PADS)

作者： A. Park R.M. Fujimoto Computational Science & Engineering Division Georgia Institute of Technology College of Computing Georgia Institute of Technology Atlanta GA USA

A master/worker paradigm for executing large-scale parallel discrete event simulation programs over networkenabled computational resources is proposed and evaluated. In contrast to conventional approaches to parallel simulation, a client/server architecture is proposed where clients (workers) repeatedly download state vectors of logical processes and associated message data from a server (master), perform simulation computations locally at the client, and then return the results back to the server. This process offers several potential advantages over conventional parallel discrete event simulation systems, including support for execution over heterogeneous distributed computing platforms, load balancing, efficient execution on shared platforms, easy addition or removal of client machines during program execution, simpler fault tolerance, and improved portability. A prototype implementation called the Aurora Parallel and Distributed Simulation System (Aurora) is described. The structure and interaction of the Aurora components is described. Results of an experimental performance evaluation are presented detailing primitive timings and application performance on both dedicated and shared computing platforms.

关键词： Throughput computational modeling Discrete event simulation Concurrent computing Network servers Large-scale systems Computer networks Computer architecture Distributed computing Load management

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Neural Networks for Clustering Analysis of Molecular Data

Neural Networks for Clustering Analysis of Molecular Data

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International Conference on Signal Processing Proceedings (ICSP)

作者： Lin Wang Minghu Jiang Xiaofang Tang Qiuqi Ruan Baozong Yuan Frank Noe School of Electronic Engineering Beijing University of Posts and Telecommunications Beijing China Lab of Computational Linguistics Department of Chinese Language Tsinghua University Beijing Beijing China Institute of Information Science Beijing Jiaotong University Beijing China Interdisciplinary Center for Scientific Computing University of Heidelberg Heidelberg Germany

In this paper hierarchical cluster and the competitive learning cluster are compared by using molecular data of large size sets. We construct a reproducible matrix to evaluate the quality of clustering, and dead nodes problem of the competitive learning network is solved by the conscience mechanism. The experimental results show that the hierarchical clustering can represent a multi-level hierarchy which show the tree relation of cluster distance, the competitive learning network has a good clustering reproducible and indicate the effectiveness of clusters for molecular data

关键词： Neural networks Data analysis Neurons Information analysis Telecommunications computational linguistics Natural languages Information science Scientific computing Unsupervised learning

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On the modelling and computation of nonlinear multibody cable systems

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International Journal of Computers and Applications 2006年第2期28卷 154-161页

作者： Fox, B. Jennings, L.S. Zomaya, A.Y. Institute of High Performance Computing Singapore Science Park 2 1 Sci. Pk. Rd. #01-01 The Capricorn 117528 Singapore Singapore Centre of Applied Dynamics and Optimization University of Western Australia Perth WA 6907 Australia School of Information Technologies University of Sydney Madsen Building F09 Sydney NSW 2006 Australia Institute of High Performance Computing Computational Solid Mechanics and Intelligent Engineering Systems Divisions Department of Mathematics University of Western Australia Perth School of Information Technologies University of Sydney

Lagrange's equations of motion are used to obtain a differential algebraic equation representing the nonlinear dynamics of cable systems approximated through the use of multibody modelling. The differential algebraic equation of index 3 is cast as an ordinary differential equation and integrated using the LSODAR software. The cable system consists of an arbitrary number of links between which restoring torques are placed to provide a damping effect. A cable car is introduced to ride upon the cable, where the initial conditions of the cable car system are determined by allowing the original cable system to fall into an equilibrium position. Graphs and animation indicate the chaotic behaviour of both multibody systems, and it is shown that the CPU time increases in a cubic nature as the number of bodies in the system increases. Finally, the accuracy of the results is investigated using a constraint compliance testing procedure.

关键词： Multi agent systems

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Automatic Differentiation: Applications, Theory, and Implementations

Lecture Notes in Computational Science and Engineering

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Lecture Notes in computational science and engineering 2006年 50卷

作者： Bücker, Martin Corliss, George Hovland, Paul Naumann, Uwe Norris, Boyana Institute for Scientific Computing RWTH Aachen University D-52056 Aachen Germany Department of Electrical and Computer Engineering Marquette University 1515 W. Wisconsin Avenue P.O. Box 1881 Milwaukee WI 53201-1881 United States Software and Tools for Computational Engineering RWTH Aachen University D-52056 Aachen Germany Mathematics and Computer Science Division Argonne National Laboratory 9700 S Cass Ave Argonne IL 60439 United States

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Boundary Integral Equations and A Posteriori Error Estimates

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Tsinghua science and Technology 2005年第1期10卷 35-42页

作者：余德浩赵龙花 Institute of Computational Mathematics and Scientific/Engineering Computing Academy of Mathematics and System Science Chinese Academy of Sciences P. O. Box 2719 Beijing 100080 China

Adaptive methods have been rapidly developed and applied in many fields of scientific and engi- neering computing. Reliable and efficient a posteriori error estimates play key roles for both adaptive finite element and boundary element methods. The aim of this paper is to develop a posteriori error estimates for boundary element methods. The standard a posteriori error estimates for boundary element methods are obtained from the classical boundary integral equations. This paper presents hyper-singular a posteriori er- ror estimates based on the hyper-singular integral equations. Three kinds of residuals are used as the esti- mates for boundary element errors. The theoretical analysis and numerical examples show that the hyper- singular residuals are good a posteriori error indicators in many adaptive boundary element computations.

关键词： boundary integral equation natural boundary reduction a posteriori error estimate hyper- singular residual pseudo-differential operator

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A new trust region algorithm for image restoration

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science China Mathematics 2005年第2期48卷 169-184页

作者： WEN Zaiwen & WANG Yanfei State Key Laboratory of Scientific engineering computing, institute of computational Mathematics and Scientific/engineering computing, Academy of Mathematics and System sciences, Chinese Academy of sciences, Beijing 100080, China National Key Laboratory on Remote Sensing science, institute of Remote Sensing Applications, Chinese Academy of sciences, Beijing 100101, China 1. State Key Laboratory of Scientific Engineering Computing Institute of Computational Mathematics and Scientific/Engineering Computing Academy of Mathematics and System Sciences Chinese Academy of Sciences 100080 Beijing China 2. National Key Laboratory on Remote Sensing Science Institute of Remote Sensing Applications Chinese Academy of Sciences 100101 Beijing China

The image restoration problems play an important role in remote sensing and astronomical image analysis. One common method for the recovery of a true image from corrupted or blurred image is the least squares error (LSE) method. But the LSE method is unstable in practical applications. A popular way to overcome instability is the Tikhonov regularization. However, difficulties will encounter when adjusting the so-called regularization parameter a. Moreover, how to truncate the iteration at appropriate steps is also challenging. In this paper we use the trust region method to deal with the image restoration problem, meanwhile, the trust region subproblem is solved by the truncated Lanczos method and the preconditioned truncated Lanczos method. We also develop a fast algorithm for evaluating the Kronecker matrix-vector product when the matrix is banded. The trust region method is very stable and robust, and it has the nice property of updating the trust region automatically. This releases us from tedious finding the regularization parameters and truncation levels. Some numerical tests on remotely sensed images are given to show that the trust region method is promising.

关键词： trust region algorithm, image restoration, Lanczos method, Kronecker matrix-vector product, preconditioning.

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