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Generalized Aitken-like acceleration of the Schwarz method

Lecture Notes in Computational science and Engineering 2005年 40卷 505-512页

作者： Baranger, Jacques Garbey, Marc Oudin-Dardun, Fabienne University Lyon 1 Modelisation and Scientific Computing France University of Houston Computer Science United States

ISBN: (纸本)3540225234

In this paper, we present a family of domain decomposition based on Aitken like acceleration of the Schwarz method seen as an iterative procedure with linear rate of convergence. This paper is a generalization of the method first introduced in Garbey and Tromeur-Dervout [2001] that was restricted to Cartesian grids. The general idea is to construct an approximation of the eigenvectors of the trace transfer operator associated to dominant eigenvalues and accelerate these components after few Schwarz iterates. We consider here examples with the finite volume approximation on general quadrangle meshes of Faille [1992] and finite element discretization.

关键词： Eigenvalues and eigenfunctions

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Hydraulic Simulation of Water Supply Networks under Control

Hydraulic Simulation of Water Supply Networks under Control

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2005 World Water and Environmental Resources Congress

作者： Deuerlein, J. Cembrowicz, R.G. Dempe, S. Kaiserstr. 12 D-76131 Karlsruhe Institute for Scientific Computing and Optimization Department of Mathematics and Computer Science Technical University Bergakademie Freiberg Leipziger Str. 28 D-09596 Freiberg

ISBN: (纸本)0784407924

The objectives of simulating the hydraulic behavior of a water supply network, being either real or planned, focus upon identifying flow, pressure and velocities, following time variant system's operation or the propagation of water quality in the network, supporting leak detection, verifying the hydraulic impact of different system's elements, guiding gauging and calibration. Existing simulation models represented by available software show different capacities regarding control devices, including pressure control valves, pressure sustaining valves, flow control valves, check valves, speed regulated pumps - operated combined and simultaneously where convergence may not be obtained. Since a rigorous mathematical approach is lacking the system's behavior is presently treated heuristically without guarantee of success. Consequently a new mathematical approach has been derived and is presented here. First, the hydraulic simulation is conceived as optimization of the system's 'Content' and 'Co-Content' functions. Second, regarding flow control devices, Convex Analysis is utilized to allow a generalization of the hydraulic equations of system's elements in the form of subdifferential mappings leading to Kuhn-Tucker conditions, amenable to solution. Third, regarding pressure control devices, the definition of a Nash Equilibrium, according to Game Theory, between the 'Co-Content' and additional minimizing problems, describing the system behavior of the devices, also leads to a solution. Hence, arbitrary flow and pressure controlling devices can now be incorporated in water supply network simulation. Convergence is assured if the system's physics are feasible. The approach has been implemented as part of the water supply network simulation & optimization model KANET. Copyright ASCE 2005.

关键词： Water supply systems

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Automatic generation of data types for classification of deep web sources

Automatic generation of data types for classification of dee...

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Second International Workshop on Data Integration in the Life sciences, DILS 2005

作者： Ngu, Anne H.H. Buttler, David Critchlow, Terence Department of Computer Science Texas State University San Marcos TX 78666 United States Center for Applied Scientific Computing Lawrence Livermore National Laboratory Livermore CA 94551 United States

ISBN: (纸本)3540279679

A Service Class Description (SCD) is an effective meta-data based approach for discovering Deep Web sources whose data exhibit some regular patterns. However, it is tedious and error prone to create an SCD description manually. Moreover, a manually created SCD is not adaptive to the frequent changes of Web sources. It requires its creator to identify all the possible input and output types of a service a priori. In many domains, it is impossible to exhaustively list all the possible input and output data types of a source in advance. In this paper, we describe machine learning approaches for automatic generation of the data types of an SCD. We propose two different approaches for learning data types of a class of Web sources. The Brute-Force Learner is able to generate data types that can achieve high recall, but with low precision. The Clustering-based Learner generates data types that have a high precision rate, but with a lower recall rate. We demonstrate the feasibility of these two learning-based solutions for automatic generation of data types for citation Web sources and presented a quantitative evaluation of these two solutions. © Springer-Verlag Berlin Heidelberg 2005.

关键词： Metadata

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Performance analysis for distributed and parallel Java programs with Aksum 05

Performance analysis for distributed and parallel Java progr...

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IEEE/ACM International Symposium on Cluster computing and the Grid (CCGRID)

作者： C. Seragiotto T. Fahringer Institute for Scientific Computing University of Technology Vienna Austria Institute of Computer Science University of Innsbruck Austria

ISBN: (纸本)9780780390744

This paper deals with the challenging problem of performance analysis for Java programs. We describe procedures and requirements for instrumenting, monitoring, and analyzing distributed Java codes, and introduces Aksum, a highly customizable and flexible system for performance analysis that helps programmers to semi-automatically locate and understand performance problems in parallel and distributed Java programs. We also describe a sophisticated agent architecture as part of Aksum for static and dynamic instrumentation of Java programs. Experiments are presented for a widely distributed application running on a heterogeneous set of machines with different operating systems to illustrate the usefulness of our approach.

关键词： Performance analysis Java Instruments Monitoring Data analysis scientific computing Programming profession Operating systems Yarn computer languages

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Analysis of Distributed Java Applications Using Dynamic Instrumentation

Analysis of Distributed Java Applications Using Dynamic Inst...

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IEEE International Conference on Cluster computing

作者： Clovis Seragiotto Thomas Fahringer Institute of Scientific Computing University of Technology Vienna Austria Institute of Computer Science University of Innsbruck Japan

Although new Java virtual machines provide an API to obtain raw performance data, it is still the task of a skillful performance analysis tool to take all the strategic decisions for instrumentation and performance analysis of distributed Java programs. In this paper we demonstrate two new tools. Twilight and Aksum, which try to automatically instrument code regions, to determine what performance data to collect, to interpret performance data, and to relate the bottlenecks found back to source code. We present experiments with a widely distributed Java application running on a heterogeneous set of machines with different operating systems to demonstrate the efficacy of our tools

关键词： Java Instruments Virtual machining Performance analysis Monitoring Yarn Distributed computing Application software Operating systems Sun

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Self-adapting Linear Algebra algorithms and software

Self-adapting Linear Algebra algorithms and software

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作者： Demmel, James Dongarra, Jack Eijkhout, Victor Fuentes, Erika Petitet, Antoine Vuduc, Richard Whaley, R.Clint Yelick, Katherine Computer Science Division Electrical Engineering and Computer Science Department University of California Berkeley CA 94720 United States Computer Science Department University of Tennessee Knoxville TN 37996 United States Computer Science and Mathematics Division Oak Ridge National Laboratory Oak Ridge TN 37831 United States Computer Science Department Rice University Houston TX United States Innovative Computing Laboratory University of Tennessee Knoxville TN 37996 United States Sun Microsystems Paris 75016 France Center for Applied Scientific Computing Lawrence Livermore National Laboratory Livermore CA 94551 United States Department of Computer Science Florida State University Tallahassee FL 32306-4530 United States Electrical Engineering and Computer Science Department University of California Berkeley CA 94720 United States

One of the main obstacles to the efficient solution of scientific problems is the problem of tuning software, both to the available architecture and to the user problem at hand. We describe approaches for obtaining tuned high-performance kernels and for automatically choosing suitable algorithms. Specifically, we describe the generation of dense and sparse Basic Linear Algebra Subprograms (BLAS) kernels, and the selection of linear solver algorithms. However, the ideas presented here extend beyond these areas, which can be considered proof of concept. © 2005 IEEE.

关键词： Linear algebra

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Fast and accurate structural RNA alignment by progressive lagrangian optimization

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1st International Symposium on Computational Life sciences, CompLife 2005

作者： Bauer, Markus Klau, Gunnar W. Reinert, Knut Algorithmic Bioinformatics Group Institute of Computer Science Free University of Berlin Germany International Max Planck Research School on Computational Biology and Scientific Computing Germany Mathematics in Life Sciences Group Institute of Mathematics Free University of Berlin Germany

ISBN: (纸本)3540291040

During the last few years new functionalities of RNA have been discovered, renewing the need for computational tools for their analysis. To this respect, multiple sequence alignment is an essential step in finding structurally conserved regions in related RNA sequences. In contrast to proteins, many classes of functionally related RNA molecules show a rather weak sequence conservation but instead a fairly well conserved secondary structure. Hence, any method that relates RNA sequences in form of multiple alignments should take structural features into account, which has been verified in recent studies. Progress has been made in developing new structural alignment algorithms, however, current methods are computationally costly or do not have the desired accuracy to make them an everyday tool. In this paper we present a fast, practical, and accurate method for computing multiple, structural RNA alignments. The method is based on combining a new pairwise structural alignment method with the popular program T-Coffee. Our pairwise method is based on an integer linear programming (ILP) formulation resulting from a graph-theoretic reformulation of the structural alignment problem. We find provably optimal or near-optimal solutions of the ILP with a Lagrangian approach. Tests on a recently published benchmark set show that our Lagrangian approach outper-forms current programs in quality and in the length of the sequences it can align. © Springer-Verlag Berlin Heidelberg 2005.

关键词： RNA

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Random beamforming in MIMO systems exploiting efficient multiuser diversity

Random beamforming in MIMO systems exploiting efficient mult...

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IEEE Conference on Vehicular Technology (VTC)

作者： Eun Yong Kim Joohwan Chun Scientific Computing Laboratory Department of Electrical Engineering and Computer Science Korea Advanced Institute of Science and Technology Daejeon South Korea

We propose a new random beamforming technique in forward link multiuser MIMO systems that exploits efficient multiuser diversity and spatial multiplexing gain. The common channels are allocated to more than one user simultaneously and multiple antennas at the receivers are used for interference nulling, resulting in higher throughput and reduced average waiting time. We show that the throughput of the proposed scheme outperforms the upper bound of the conventional scheme.

关键词： MIMO Array signal processing Diversity reception Base stations Receiving antennas Throughput Mobile antennas Interference Fading Transmitters

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A survey of IPv6 site multihoming proposals

A survey of IPv6 site multihoming proposals

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International Conference on Telecommunications (ConTEL)

作者： P. Savola T. Chown CSC-Scientific Computing Limited Espoo Finland School of Electronics and Computer Science University of Southampton Southampton UK

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Two-level preconditioning techniques for electromagnetic wave scattering problems

Two-level preconditioning techniques for electromagnetic wav...

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2005 IEEE/ACES International Conference on Wireless Communications and Applied Computational Electromagnetics

作者： Lee, Jeonghwa Zhang, Jun Lu, Cai-Cheng RAPT Industries Inc. 183 Northpointe Blvd. Freeport PA 16229 United States Laboratory for High Performance Scientific Computing and Computer Simulation Department of Computer Science University of Kentucky Lexington KY 40506 United States Department of Electrical and Computer Engineering University of Kentucky Lexington KY40506 United States

ISBN: (纸本)0780390687

We investigate preconditioned iterative solutions of large dense complex valued matrices arising from discretizing the hybrid integral equations of electromagnetic scattering. Due to the specific data pattern, we propose to construct two-level (TL) preconditioners to treat the conducting and dielectric parts more efficiently. The main purpose of this study is to show that the TL preconditioning is effective with the MLFMA and can reduce the number of Krylov iterations substantially by using subdivided domain of the near part matrix for each level. Our experimental results indicate that the TL preconditioning maintains the computational complexity of the MLFMA, but converges much faster, thus effectively reduces the overall simulation time for the coated material objects. © 2005 ACES.

关键词： Iterative methods

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