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 basis for the numerical solution of the non-hyper-singular displacement and traction BIEs. By employing the various types of test functions, several types of MLPG/BIEs are formulated. Numerical examples show that the present methods are very promising, especially for solving the elastic problems in which the singularities in displacements, strains, and stresses are of primary concern.

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 of displacement compatibility, two numerical techniques, using the hybrid displacement shape function and the modified variational form, are developed and discussed in this paper. In the first technique, the original MFree shape functions are modified to the hybrid forms that possess the Kronecker delta function property. In the second technique, the displacement compatibility is satisfied via a modified variational form based on the Lagrange multiplier method. Formulations of several coupled methods are presented. Numerical examples are presented to demonstrate the effectiveness of the present coupling methods.

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 new boundary element algorithms match very well with the results using a commercial finite element code, and clearly demonstrate the feasibility of the new boundary element approach for 3-D contact analysis.

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 potential equations for inclusion or hole problems. Numerical results for a piezoelectric plate with circular inclusions are presented to illustrate applications of the proposed micromechanics-BEM formulation.

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-singular a posteriori error estimates based on the hyper-singular integral equations. Three kinds of residuals are used as the estimates 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.

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 the solution at the same time. A modified Gaussian elimination algorithm was developed to improve the solution efficiency of the final system equation. Numerical examples verify the validity of the proposed algorithm.

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 to the conventional BEM.

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 mathematical friction model to the 3-D elastic multipole BEM to develop a 3-D elasto-plastic contact multipole BEM. Numerical tests show that with this new method, the needed computer memory size is only 2% of the traditional BEM model with friction, which erases large-scale computing with refined meshes and improves the computational accuracy.

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 computational parameters are chosen based on a thorough numerical study of 1-dimensional problems. Several 2-dimensional examples show that the MWLS method is much faster than the element free Galerkin method (EFGM), while the accuracy of the MWLS method is close to, or even better than the EFGM. These numerical results demonstrate that the MWLS method has good potential for numerical analyses of heat transfer problems.

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 of thin structures, the FM-BEM is much more efficient than the conventional BEM and the accuracy achieved is sufficient for engineering applications.

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 CPU time and less memory. A new initial candidate vector for the iterative solver was developed to further improve the efficiency. The numerical examples apply the method to the analysis of cracks in infinite 2-D space with the largest model having 900 000 degrees of freedom.

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 ignores the negative influence of image noise to obtain an accurate foreground map than other foreground detection algorithms. Most shadow pixels are also eliminated by this method.

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 localized with heterogeneous sensors. The approach was implemented in an experimental platform consisting of car-like mobile robots equipped with omnidirectional video cameras and IEEE 802.11b wireless networking. The experimental results validate the approach.

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 characterizing the retailer's optimal solutions, this paper demonstrates that contrary to intuition, loss aversion weakens incentives for retailer's sales effort and the retailer's optimal effort decreases as the loss aversion increases.

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 programming/binary interface API/ABI compliance. In addition, TH-CluFS uses a serverless architecture which flexibly distributes data at file granularity and achieves a consistent file system view from distributed metadata. The global cache makes full use of the aggregated memories and disks in the cluster to optimize system performance. Experimental results suggest that although TH-CluFS is implemented as user-level components, it functions as a portable, single system image, and scalable cluster file system with acceptable performance sacrifices.

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 target, designed and implemented to support this structure, obeys the SCSI protocol and works in target mode with 200 MB/s bandwidth. The FC target architecture and implementation were compared with the FC initiator. The SCSI command transfer process in the FC layer was described. The performance test results show that the maximum I/O throughput reachs 167 MB/s for read requests and 196 MB/s for write requests (FC bandwidth is 200 MB/s), verifying that the FC target is very efficient. The modularization, efficiency, and low cost of the FC target will enable SAN and fibre channel to be more widely used in applications.

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 SCSI command addresses. The system uses the bitmap technique to manage the free space. The storage virtualization system provides various functions, such as logical volume resizing, data mirroring, and snapshots, and is compatible with clustered hosts and multiple operating systems, such as Windows NT and RedHat.

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 curves in computer aided geometric design systems, and provides a method for joining two limit curves of interpolating ternary subdivisions.