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, K_IP. Furthermore, the addition of the negative stress intensity factor (SIF), K_IA, resulting from the residual stress field due to autofrettage, whether ideal or… More >

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 >

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 >

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 >

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 >

Dalin Tang^*, Chun Yang^†, Tal Geva^‡,§, Pedro J. del Nido^¶

Molecular & Cellular Biomechanics, Vol.4, No.3, pp. 159-176, 2007, DOI:10.3970/mcb.2007.004.159

Abstract A single-layer isotropic patient-specific right/left ventricle and patch (RV/LV/Patch) combination model with fluid-structure interactions (FSI) was introduced in our previous papers to evaluate and optimize human pulmonary valve replacement/insertion (PVR) surgical procedure and patch design. In this paper, an active anisotropic model with two-layer structure for ventricle wall and tissue fiber orientation was introduced to improve previous isotropic model for more accurate assessment of RV function and potential application in PVR surgery and patch design. A material-stiffening approach was used to model active heart contraction. The computational models were used to conduct ``virtual (computational)'' surgeries More >

Chun Yang¹, Dalin Tang², Chun Yuan³, Thomas S. Hatsukami⁴, Jie Zheng⁵, Pamela K. Woodard⁵

CMES-Computer Modeling in Engineering & Sciences, Vol.19, No.3, pp. 233-246, 2007, DOI:10.3970/cmes.2007.019.233

Abstract It has been recognized that fluid-structure interactions (FSI) play an important role in cardiovascular disease initiation and development. However, in vivo MRI multi-component FSI models for human carotid atherosclerotic plaques with bifurcation and quantitative comparisons of FSI models with fluid-only or structure-only models are currently lacking in the literature. A 3D non-Newtonian multi-component FSI model based on in vivo/ex vivo MRI images for human atherosclerotic plaques was introduced to investigate flow and plaque stress/strain behaviors which may be related to plaque progression and rupture. Both artery wall and plaque components were assumed to be hyperelastic,… More >

D.L. Young¹, K.H. Chen², J.T. Chen³, J.H. Kao⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.19, No.3, pp. 197-222, 2007, DOI:10.3970/cmes.2007.019.197

Abstract A boundary-type method for solving the Laplace problems using the modified method of fundamental solutions (MMFS) is proposed. The present method (MMFS) implements the singular fundamental solutions to evaluate the solutions, and it can locate the source points on the real boundary as contrasted to the conventional MFS, where a fictitious boundary is needed to avoid the singularity of diagonal term of influence matrices. The diagonal term of influence matrices for arbitrary domain can be novelly determined by relating the MFS with the indirect BEM and are also solved for circular domain analytically by using More >

Chein-Shan Liu¹

CMC-Computers, Materials & Continua, Vol.6, No.2, pp. 117-128, 2007, DOI:10.3970/cmc.2007.006.117

Abstract In this paper the Landau-Lifshitz equation is subjected to a circularly polarized field in the plane, as well as both a dc field and an anisotropy field along the vertical easy axis perpendicular to the plane. The representation of Landau-Lifshitz equation in the Minkowski space is a Lie-type system. By performing a computation through the Lie-group solvers we can develop a consistent numerical method, which satisfies the consistency condition exactly, and thus can retain the invariant behavior. Then, we use the consistent numerical method to investigate the magnetization reversal, whose switching criterion is displayed through More >

Chein-Shan Liu^1,2

CMC-Computers, Materials & Continua, Vol.5, No.2, pp. 151-160, 2007, DOI:10.3970/cmc.2007.005.151

Abstract An accurate magnetization requires that both the reversible and irreversible components be modeled. The classical Landau-Lifshitz model deals with only the irreversible component of magnetization. We first subject the Landau-Lifshitz equation to an AC external field by performing a computation through the closed-form solution and the resulting hysteresis loop is displayed to show its deficiency. Then we modify the Landau-Lifshitz model into a new one by including a reversible part and an irreversible part accompanying with the switching criteria between these two states. With the new solutions we display the influence of parameters on the More >