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  • Open Access

    ARTICLE

    Regularized MFS-Based Boundary Identification in Two-Dimensional Helmholtz-Type Equations

    Liviu Marin1, Andreas Karageorghis2

    CMC-Computers, Materials & Continua, Vol.10, No.3, pp. 259-294, 2009, DOI:10.3970/cmc.2009.010.259

    Abstract We study the stable numerical identification of an unknown portion of the boundary on which a given boundary condition is provided and additional Cauchy data are given on the remaining known portion of the boundary of a two-dimensional domain for problems governed by either the Helmholtz or the modified Helmholtz equation. This inverse geometric problem is solved using the method of fundamental solutions (MFS) in conjunction with the Tikhonov regularization method. The optimal value for the regularization parameter is chosen according to Hansen's L-curve criterion. The stability, convergence, accuracy and efficiency of the proposed method More >

  • Open Access

    ABSTRACT

    The Descending Aortic Aneurysm under Vascular Structure having Three-layered using FSI

    O. Ohta1, F. Gao1, T. Matsuzawa2

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.7, No.3, pp. 146-150, 2008, DOI:10.3970/icces.2008.007.146

    Abstract The aortic disease is 2nd place of the cause of death. If the thoracic part and the dissociation are matched, the aortic aneurysm exceeds 60 percent. The aneurysm decided based on the maximum diameter of the aneurysm from the image of which it takes a picture with CT or MRI etc. as such a diagnostic indicator. The appearance of disease, the development, and the rupture of the arterial hemangioma are thought that the hemodynamics such as intravasculars and vessel walls plays an important role [1,2]. Then, we simulated the aneurysm of descending aorta in consideration More >

  • Open Access

    ABSTRACT

    FDMFS for Diffusion Equation with Unsteady Forcing Function

    S.P. Hu1, D.L. Young1,2, C.M. Fan1

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.6, No.1, pp. 25-50, 2008, DOI:10.3970/icces.2008.006.025

    Abstract In this paper, a novel numerical scheme called (FDMFS), which combines the finite difference method (FDM) and the method of fundamental solutions (MFS), is proposed to simulate the nonhomogeneous diffusion problem with an unsteady forcing function. Most meshless methods are confined to the investigations of nonhomogeneous diffusion equations with steady forcing functions due to the difficulty to find an unsteady particular solution. Therefore, we proposed a FDM with Cartesian grid to handle the unsteady nonhomogeneous term of the equations. The numerical solution in FDMFS is decomposed into a particular solution and a homogeneous solution. The… More >

  • Open Access

    ARTICLE

    Stable MFS Solution to Singular Direct and Inverse Problems Associated with the Laplace Equation Subjected to Noisy Data

    LiviuMarin 1

    CMES-Computer Modeling in Engineering & Sciences, Vol.37, No.3, pp. 203-242, 2008, DOI:10.3970/cmes.2008.037.203

    Abstract In this paper, a meshless method for the stable solution of direct and inverse problems associated with the two-dimensional Laplace equation in the presence of boundary singularities and noisy boundary data is proposed. The governing equation and boundary conditions are discretized by the method of fundamental solutions (MFS), whilst the existence of the boundary singularity is taken into account by subtracting from the original MFS solution the corresponding singular solutions, as given by the asymptotic expansion of the solution near the singular point. However, even in the case when the boundary singularity is accounted for, More >

  • Open Access

    ARTICLE

    A Numerical Meshfree Technique for the Solution of the MEW Equation

    Sirajul Haq1, Siraj-ul-Islam2, Arshed Ali3

    CMES-Computer Modeling in Engineering & Sciences, Vol.38, No.1, pp. 1-24, 2008, DOI:10.3970/cmes.2008.038.001

    Abstract In this paper we propose a meshfree technique for the numerical solution of the modified equal width wave (MEW) equation. Combination of collocation method using the radial basis functions (RBFs) with first order accurate forward difference approximation is employed for obtaining meshfree solution of the problem. Different types of RBFs are used for this purpose. Performance of the proposed method is successfully tested in terms of various error norms. In the case of non-availability of exact solution, performance of the new method is compared with the results obtained from the existing methods. Propagation of a More >

  • Open Access

    ARTICLE

    The Bauschinger Effect on 3-D SIFs for Networks of Radial and Longitudinally-Coplanar Semi-Elliptical Internal Surface Cracks In Autofrettaged Pressurized Thick-Walled Cylinders

    Q. Ma1, C. Levy2, M. Perl3

    CMES-Computer Modeling in Engineering & Sciences, Vol.29, No.2, pp. 95-110, 2008, DOI:10.3970/cmes.2008.029.095

    Abstract Networks of radial and longitudinally-coplanar, internal, surface cracks are typical in rifled, autofrettaged, gun barrels. In two previous papers, the separate effects of large arrays of either radial or longitudinally-coplanar semi-elliptical, internal, surface cracks in a thick-walled, cylindrical, pressure vessel under both ideal and realistic autofrettage were studied. When pressure is considered solely, radial crack density and longitudinal crack spacing were found to have opposing effects on the prevailing stress intensity factor, KIP. Furthermore, the addition of the negative stress intensity factor (SIF), KIA, resulting from the residual stress field due to autofrettage, whether ideal or… More >

  • Open Access

    ARTICLE

    Improving the Ill-conditioning of the Method of Fundamental Solutions for 2D Laplace Equation

    Chein-Shan Liu1

    CMES-Computer Modeling in Engineering & Sciences, Vol.28, No.2, pp. 77-94, 2008, DOI:10.3970/cmes.2008.028.077

    Abstract The method of fundamental solutions (MFS) is a truly meshless numerical method widely used in the elliptic type boundary value problems, of which the approximate solution is expressed as a linear combination of fundamental solutions and the unknown coefficients are determined from the boundary conditions by solving a linear equations system. However, the accuracy of MFS is severely limited by its ill-conditioning of the resulting linear equations system. This paper is motivated by the works of Chen, Wu, Lee and Chen (2007) and Liu (2007a). The first paper proved an equivalent relation of the Trefftz… More >

  • Open Access

    ARTICLE

    FDMFS for Diffusion Equation with Unsteady Forcing Function

    S.P. Hu1, D.L. Young2, C.M. Fan1

    CMES-Computer Modeling in Engineering & Sciences, Vol.24, No.1, pp. 1-20, 2008, DOI:10.3970/cmes.2008.024.001

    Abstract In this paper, a novel numerical scheme called (FDMFS), which combines the finite difference method (FDM) and the method of fundamental solutions (MFS), is proposed to simulate the nonhomogeneous diffusion problem with an unsteady forcing function. Most meshless methods are confined to the investigations of nonhomogeneous diffusion equations with steady forcing functions due to the difficulty to find an unsteady particular solution. Therefore, we proposed a FDM with Cartesian grid to handle the unsteady nonhomogeneous term of the equations. The numerical solution in FDMFS is decomposed into a particular solution and a homogeneous solution. The… More >

  • Open Access

    ARTICLE

    Effects of prenatal stress on male offspring sexual maturity

    NANCY RODRÍGUEZ, NORA MAYER, HÉCTOR F. GAUNA

    BIOCELL, Vol.31, No.1, pp. 67-74, 2007, DOI:10.32604/biocell.2007.31.067

    Abstract Prenatal stimulations have been shown to have long-term effects on at reproductive activity. We evaluated the influence of the prenatal stress on the hypothalamic-pituitary-gonad (HPG) axis in male offsprings from mothers with high number of offsprings per litter (HNL) and low number of offsprings per litter (LNL) after hypothesizing that the number of offsprings per litter may modify the effect of the prenatal stress on the HPG of adult offsprings. Pregnant Wistar rats were used for this study. Immobilization (IMO) stress was used, 30 min, 3 times per week, from the 5th to 21st day… More >

  • Open Access

    ABSTRACT

    Wave propagation in the presence of empty cracks in elastic slabs -- TBEM and MFS Formulations

    A. Tadeu1, L. Godinho1, J. António1, P. Amado Mendes1

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.3, No.3, pp. 163-168, 2007, DOI:10.3970/icces.2007.003.163

    Abstract This paper evaluates the 3D wave propagation in an elastic slab containing cracks whose geometry does not change along the direction parallel to the formation surfaces. Two different formulations are used and compared: the Traction Boundary Element Method (TBEM) and the Method of Fundamental Solutions (MFS). Both approaches are developed in the frequency domain and surmount the thin-body difficulty posed by the classical Boundary Element Method (BEM). The TBEM models the crack as a single line. The resulting hypersingular integrals are evaluated analytically. For the MFS, the solution is approximated in terms of a linear More >

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