Tsinghua Science and Technology

Weakly-Singular Traction and Displacement Boundary Integral Equations and Their Meshless Local Petrov-Galerkin Approaches

Zhidong Han, Zhenhan Yao, S.N. Atluri

2005, 10(1): 1-7. doi:10.1016/S1007-0214(05)70002-X

Abstract ( 165 ) ( 502 )

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The general meshless local Petrov-Galerkin (MLPG) weak forms of the displacement and traction boundary integral equations (BIEs) are presented for solids undergoing small deformations. Using the directly derived non-hyper-singular integral equations for displacement gradients, simple and straight-forward derivations of weakly singular traction BIEs for solids undergoing small deformations are also presented. As a framework for meshless approaches, the MLPG weak forms provide the most general bas...

Meshless Methods Coupled with Other Numerical Methods

Y.T. Gu, G.R. Liu

2005, 10(1): 8-15. doi:10.1016/S1007-0214(05)70003-1

Abstract ( 159 ) ( 542 )

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Meshless or mesh-free (or shorten as MFree) methods have been proposed and achieved remarkable progress over the past few years. The idea of combining MFree methods with other existing numerical techniques such as the finite element method (FEM) and the boundary element method (BEM), is naturally of great interest in many practical applications. However, the shape functions used in some MFree methods do not have the Kronecker delta function property. In order to satisfy the combined conditions o...

Analysis of 3-D Frictional Contact Mechanics Problems by a Boundary Element Method

Bangyong Keum, Yijun Liu

2005, 10(1): 16-29. doi:10.1016/S1007-0214(05)70004-3

Abstract ( 232 ) ( 531 )

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The development of two boundary element algorithms for solving 3-D, frictional, and linear elastostatic contact problems is reported in this paper. The algorithms employ nonconforming discretizations for solving 3-D boundary element models, which provide much needed flexibility in the boundary element modeling for 3-D contact problems. These algorithms are implemented in a new 3-D boundary element code and verified using several examples. For the numerical examples studied, the results using the...

Micromechanics-BEM Analysis for Piezoelectric Composites

Qinghua Qin

2005, 10(1): 30-34. doi:10.1016/S1007-0214(05)70005-5

Abstract ( 139 ) ( 479 )

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The effective material properties of piezoelectric composites are predicted using micromechanics models of the composite structure combined with a boundary element method (BEM) solution of the governing equation. The composites consist of inclusion and matrix phases. The micromechanics method gives formulae for the overall material constants as functions of the concentration matrix, while the boundary element simulation gives numerical solutions of the boundary displacement and electric potentia...

Boundary Integral Equations and A Posteriori Error Estimates

Dehao Yu, Longhua Zhao

2005, 10(1): 35-42. doi:10.1016/S1007-0214(05)70006-7

Abstract ( 104 ) ( 470 )

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Adaptive methods have been rapidly developed and applied in many fields of scientific and engineering 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-sing...

Multi-Variable Non-Singular BEM for 2-D Potential Problems

Haibo Chen, Jianfeng Jin, Peiqiang Zhang, Pin L�

2005, 10(1): 43-50. doi:10.1016/S1007-0214(05)70007-9

Abstract ( 129 ) ( 486 )

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A multi-variable non-singular boundary element method (MNBEM) is presented for 2-D potential problems. This method is based on the coincident collocation of non-singular boundary integral equations (BIEs) of the potential and its derivatives, where the nodal potential derivatives are considered independent of the nodal potential and flux. The system equation is solved to determine the unknown boundary potentials and fluxes, with high accuracy boundary nodal potential derivatives obtained from th...

Mathematical Programming Solution for the Frictional Contact Multipole BEM

Chunxiao Yu, Guangxian Shen, Deyi Liu

2005, 10(1): 51-56. doi:10.1016/S1007-0214(05)70008-0

Abstract ( 187 ) ( 525 )

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This paper presents a new mathematical model for the highly nonlinear problem of frictional contact. A programming model, multipole boundary element method (BEM), was developed for 3-D elastic contact with friction to replace the Monte Carlo method. A numerical example shows that the optimization programming model for the point-to-surface contact with friction and the fast optimization generalized minimal residual algorithm (GMRES(m)) significantly improve the analysis of such problems relative ...

Multipole BEM for 3-D Elasto-Plastic Contact with Friction

Deyi Liu, Guangxian Shen

2005, 10(1): 57-60. doi:10.1016/S1007-0214(05)70009-2

Abstract ( 164 ) ( 515 )

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The analysis of 3-D elasto-plastic contact with friction is a highly nonlinear problem. The elements in the contact and plastic zones should be refined to obtain accurate information about the real size, displacement, and traction in the contact zone. However, the increase in the number of degrees of freedom is limited when traditional boundary element method (BEM) is used with the larger memory size and long CPU time required for the solution procedure. This paper describes the additional mathe...

Meshless Least-Squares Method for Solving the Steady-State Heat Conduction Equation

Yan Liu, Xiong Zhang, Mingwan Lu

2005, 10(1): 61-66. doi:10.1016/S1007-0214(05)70010-9

Abstract ( 157 ) ( 486 )

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The meshless weighted least-squares (MWLS) method is a pure meshless method that combines the moving least-squares approximation scheme and least-square discretization. Previous studies of the MWLS method for elastostatics and wave propagation problems have shown that the MWLS method possesses several advantages, such as high accuracy, high convergence rate, good stability, and high computational efficiency. In this paper, the MWLS method is extended to heat conduction problems. The MWLS computa...

Fast Multipole BEM for 3-D Elastostatic Problems with Applications for Thin Structures

Libin Zhao, Zhenhan Yao

2005, 10(1): 67-75. doi:10.1016/S1007-0214(05)70011-0

Abstract ( 181 ) ( 517 )

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The fast multipole method (FMM) has been used to reduce the computing operations and memory requirements in large numerical analysis problems. In this paper, the FMM based on Taylor expansions is combined with the boundary element method (BEM) for three-dimensional elastostatic problems to solve thin plate and shell structures. The fast multipole boundary element method (FM-BEM) requires O(N) operations and memory for problems with N unknowns. The numerical results indicate that for the analysis...

Fast Multipole BEM for Simulation of 2-D Solids Containing Large Numbers of Cracks

Pengbo Wang, Zhenhan Yao, Haitao Wang

2005, 10(1): 76-81. doi:10.1016/S1007-0214(05)70012-2

Abstract ( 132 ) ( 494 )

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The fast multipole method was used to solve the traction boundary integral equation for 2-D crack analysis. The use of both multipole and local expansions reduces both the computational complexity and the memory requirement to O(N). The multipole expansion uses a complex Taylor series expansion to reduce the number of multipole moments. The generalized minimum residual method solver (GMRES) was selected as the iterative solver. An improved preconditioner for GMRES was developed which uses less C...

Adaptive Contour Model for Real-Time Foreground Detection

Ying Huang, Xiaoqing Ding

2005, 10(1): 82-90. doi:10.1016/S1007-0214(05)70013-4

Abstract ( 190 ) ( 486 )

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A multiscale foreground detection method was developed to segment moving objects from a stationary background. The algorithm is based on a fixed-mesh-based contour model, which starts at the bounding box of the difference map between an input image and its background and ends at a final contour. An adaptive algorithm was developed to calculate an appropriate energy threshold to control the contours to identify the foreground silhouettes. Experiments show that this method more successfully ignore...

Cooperative Localization and Tracking in Distributed Robot-Sensor Networks

Fan Zhang, Guilherme S. Pereira, Vijay Kumar

2005, 10(1): 91-101. doi:10.1016/S1007-0214(05)70014-6

Abstract ( 126 ) ( 468 )

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This paper addresses the problem of real-time position and orientation estimation of networked mobile robots in two-dimensional Euclidean space with simultaneous tracking of a rigid unknown object based on exteroceptive sensory information extracted from distributed vision systems. The sufficient and necessary conditions for team localization are proposed. A localization and object tracking approach based on statistical operators and graph searching algorithms is presented for a team of robots l...

Supply Chain Coordination with Sales Effort Effects and Impact of Loss Aversion on Effort Decision

Hansheng Suo, Jingchun Wang, Yihui Jin

2005, 10(1): 102-107. doi:10.1016/S1007-0214(05)70015-8

Abstract ( 125 ) ( 484 )

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A new supply contract based on sharing the sales profits as well as the cost of effort was developed to coordinate the supply chain with sales effort effects. The contract coordinates the supplier's actions with voluntary compliance; the contract is symmetric in the sense that both the supplier's and retailer's profits are linearly correlated and is more easily implemented in some situations. The impact of the retailer's loss aversion on his effort is investigated based on the contract. After ch...

Building a Portable File System for Heterogeneous Clusters

Qifeng Huang, Guangwen Yang, Weimin Zheng, Meiming Shen, Yiyan Deng

2005, 10(1): 108-114. doi:10.1016/S1007-0214(05)70016-X

Abstract ( 166 ) ( 523 )

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Existing in-kernel distributed file systems cannot cope with the higher requirements in well-equipped cluster environments, especially when the system becomes larger and inevitably heterogeneous. TH-CluFS is a cluster file system designed for large heterogeneous systems. TH-CluFS is implemented completely in the user space by emulating the network file system (NFS) V2 server, and is easily portable to other portable operating system interface (POSIX)-compliant platforms with application programm...

Design and Implementation of a Fibre Channel Target Driver Supporting SCSI

Hao Wu, Jiwu Shu, Dongchan Wen, Weimin Zheng

2005, 10(1): 115-121. doi:10.1016/S1007-0214(05)70017-1

Abstract ( 177 ) ( 476 )

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Fibre channel storage area networks (FC-SAN) are effective solutions to address storage management problems caused by very large volumes of data. But the expense of fibre channel devices limits FC-SAN applications. The use of IP networks instead of fibre channel networks will reduce SAN cost, but will also reduce the performance. Therefore, small computer system interface (SCSI) devices were considered to replace FC disks to reduce the SAN cost. A driver for the FC network adapter and the FC tar...

Design and Implementation of a Storage Virtualization System Based on SCSI Target Simulator in SAN

Bigang Li, Jiwu Shu, Weimin Zheng

2005, 10(1): 122-127. doi:10.1016/S1007-0214(05)70018-3

Abstract ( 192 ) ( 493 )

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The ideal storage virtualization system is compatible with all operating systems in storage area networks (SANs). However, current storage systems on clustered hosts and multiple operating systems are not practical. This paper presents a storage virtualization system based on a SCSI target simulator in a SAN to solve these problems. This storage virtualization system runs in the target hosts of the SAN, dynamically stores the physical information, and uses the mapping table method to modify the ...

Improved Ternary Subdivision Interpolation Scheme

Huawei Wang, Kaihuai Qin

2005, 10(1): 128-132. doi:10.1016/S1007-0214(05)70019-5

Abstract ( 140 ) ( 477 )

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An improved ternary subdivision interpolation scheme was developed for computer graphics applications that can manipulate open control polygons unlike the previous ternary scheme, with the resulting curve proved to be still C2-continuous. Parameterizations of the limit curve near the two endpoints are given with expressions for the boundary derivatives. The split joint problem is handled with the interpolating ternary subdivision scheme. The improved scheme can be used for modeling interpolation...

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