CMES-Vol. 37, No. 2, 2008

Open Access

ARTICLE

A Study of Boundary Conditions in the Meshless Local Petrov-Galerkin (MLPG) Method for Electromagnetic Field Computations
Meiling Zhao¹, Yufeng Nie²
CMES-Computer Modeling in Engineering & Sciences, Vol.37, No.2, pp. 97-112, 2008, DOI:10.3970/cmes.2008.037.097
Abstract Meshless local Petrov-Galerkin (MLPG) method is successfully applied for electromagnetic field computations. The moving least square technique is used to interpolate the trial and test functions. More attention is paid to imposing the essential boundary conditions of electromagnetic equations. A new coupled meshless local Petrov-Galerkin and finite element (MLPG-FE) method is presented to enforce the essential boundary conditions. Unlike the conventional coupled technique, this approach can ensure the smooth blending of the potential variables as well as their derivatives in the transition region between the meshless and finite element domains. Then the boundary singular weight method is proposed to enforce… More >

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ARTICLE

Inverse Sensitivity Analysis of Singular Solutions of FRF matrix in Structural System Identification
S. Venkatesha¹, R. Rajender², C. S. Manohar³
CMES-Computer Modeling in Engineering & Sciences, Vol.37, No.2, pp. 113-152, 2008, DOI:10.3970/cmes.2008.037.113
Abstract The problem of structural damage detection based on measured frequency response functions of the structure in its damaged and undamaged states is considered. A novel procedure that is based on inverse sensitivity of the singular solutions of the system FRF matrix is proposed. The treatment of possibly ill-conditioned set of equations via regularization scheme and questions on spatial incompleteness of measurements are considered. The application of the method in dealing with systems with repeated natural frequencies and (or) packets of closely spaced modes is demonstrated. The relationship between the proposed method and the methods based on inverse sensitivity of eigensolutions… More >

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Numerical Simulation of Graphite Properties Using X-ray Tomography and Fast Multipole Boundary Element Method
H. T. Wang, G. Hall, S. Y. Yu, Z. H. Yao
CMES-Computer Modeling in Engineering & Sciences, Vol.37, No.2, pp. 153-174, 2008, DOI:10.3970/cmes.2008.037.153
Abstract Graphite materials are widely used in gas-cooled nuclear reactors as both moderators and reflectors. The graphite properties change when the microstructure damage occurs due to the in-core radiation and oxidation, thereby having a strong impact on the service life of graphite. In this paper, the X-ray tomography and the boundary element method (BEM) are introduced to the microstructure modeling and numerical simulations of both the mechanical and thermal property changes of nuclear graphite due to radiolytic oxidation. The model is established by the three-dimensional X-ray scan on the isotropic nuclear graphite Gilsocarbon, which is used in the UK commercial reactors.… More >

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ARTICLE

Topological Shape Optimization of Electromagnetic Problems using Level Set Method and Radial Basis Function
Hokyung Shim¹, Vinh Thuy Tran Ho^1,,Semyung Wang^1,2, Daniel A. Tortorelli³
CMES-Computer Modeling in Engineering & Sciences, Vol.37, No.2, pp. 175-202, 2008, DOI:10.3970/cmes.2008.037.175
Abstract This paper presents a topological shape optimization technique for electromagnetic problems using a level set method and radial basis functions. The proposed technique is a level set (LS) based optimization dealing with geometrical shape derivatives and topological design. The shape derivative is computed by an adjoint variable method to avoid numerous sensitivity evaluations. A level set model embedded into the scalar function of higher dimensions is propagated to represent the design boundary of a domain. The level set function interpolated into a fixed initial domain is evolved by using the Hamilton-Jacobi equation. The moving free boundaries (dynamic interfaces) represented in… More >

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