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  • Open Access

    ARTICLE

    Scalable Electromagnetic Simulation Environment

    Raju R. Namburu1, Eric R. Mark, Jerry A. Clarke

    CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.5, pp. 443-454, 2004, DOI:10.3970/cmes.2004.005.443

    Abstract Computational electromagnetic (CEM) simulations of full-range military vehicles play a critical role in enhancing the survivability and target recognition of combat systems. Modeling of full-range military systems subjected to high frequencies may involve generating large-scale meshes, solving equations, visualization, and analysis of results in the range of billions of unknowns or grid points. Hence, the overall objective of this research is to develop and demonstrate a scalable CEM software environment to address accurate prediction of radar cross sections (RCS) for full- range armored vehicles with realistic material treatments and complex geometric configurations. A software environment… More >

  • Open Access

    ARTICLE

    Transform Domain Based Hybrid Element Formulations for Transient Electromagnetic Field Computations

    P. Jose1, R.Kanapady2, K.K.Tamma3

    CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.5, pp. 409-422, 2004, DOI:10.3970/cmes.2004.005.409

    Abstract In this article, a novel hybrid finite element and Laplace transform formulation is presented for the computations of transient electromagnetic fields. The formulation is first based on application of Laplace transform technique for the pertinent differential equations, namely the Maxwell's equation in the non-integral form with subsequently, employing the Galerkin finite element formulations on the transformed equations to maintain the modeling versatility of complex geometries and numerical features for computational analysis. In addition, in conjunction with the above, proper scaling of the field quantities is applied to improve the condition of the effective global stiffness More >

  • Open Access

    ARTICLE

    High-Order Accurate Methods for Time-domain Electromagnetics

    J. S. Hesthaven1, T. Warburton2

    CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.5, pp. 395-408, 2004, DOI:10.3970/cmes.2004.005.395

    Abstract We discuss the formulation, validation, and parallel performance of a high-order accurate method for the time-domain solution of the three-dimensional Maxwell's equations on general unstructured grids. Attention is paid to the development of a general discontinuous element/penalty approximation to Maxwell's equations and a locally divergence free form of this. We further discuss the motivation for using a nodal Lagrangian basis for the accurate and efficient representation of solutions and operators. The performance of the scheme is illustrated by solving benchmark problems as well as large scale scattering applications. More >

  • Open Access

    ARTICLE

    Parallel 3D Time Domain Electromagnetic Scattering Simulations on Unstructured Meshes

    O. Hassan1, K. Morgan, J. Jones, B. Larwood, N. P. Weatherill

    CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.5, pp. 383-394, 2004, DOI:10.3970/cmes.2004.005.383

    Abstract A numerical procedure for the simulation of 3D problems involving the scattering of electromagnetic waves is presented. As practical problems of interest in this area often involve domains of complex geometrical shape, an unstructured mesh based method is adopted. The solution algorithm employs an explicit finite element procedure for the solution of Maxwell's curl equations in the time domain using unstructured tetrahedral meshes. A PML absorbing layer is added at the artificial far field boundary that is created by the truncation of the physical domain prior to the numerical solution. The complete solution procedure is More >

  • Open Access

    ARTICLE

    Integrated Green's Function Molecular Dynamics Method for Multiscale Modeling of Nanostructures: Application to Au Nanoisland in Cu1

    V.K. Tewary2, D.T. Read2

    CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.4, pp. 359-372, 2004, DOI:10.3970/cmes.2004.006.359

    Abstract An integrated Green's function and molecular dynamics technique is developed for multiscale modeling of a nanostructure in a semi-infinite crystal lattice. The equilibrium configuration of the atoms inside and around the nanostructure is calculated by using molecular dynamics that accounts for nonlinear interatomic forces. The molecular dynamics is coupled with the lattice statics Green's function for a large crystallite containing a million or more atoms. This gives a fully atomistic description of a nanostructure in a large crystallite that includes the effect of nonlinear forces. The lattice statics Green's function is then related to the… More >

  • Open Access

    ARTICLE

    Asymptotic Postbuckling Analysis of Composite and Sandwich Structures via the Assumed Strain Solid Shell Element Formulation

    Jihan Kim1, Yong Hyup Kim1, Sung Won Lee2

    CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.3, pp. 263-276, 2004, DOI:10.3970/cmes.2004.006.263

    Abstract The Koiter's asymptotic method is combined with the assumed strain solid shell element formulation for postbuckling analysis of composite and sandwich structures. The assumed strain solid shell element is free of locking and the small angle assumption, and it allows multiple plies through the element thickness. While laminated composite structures are modeled with single element through the thickness, sandwich structures are modeled with three elements stacked through the thickness to model the face sheets and the core independently. The Koiter's method is used to trace initial postbuckling path. Subsequently, the Koiter's method is switched to More >

  • Open Access

    ARTICLE

    Crack-Path Analysis for Brittle and Non-Brittle Cracks: A Cell Method Approach

    E. Ferretti1

    CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.3, pp. 227-244, 2004, DOI:10.3970/cmes.2004.006.227

    Abstract Defining the crack path in brittle and non-brittle crack is not easy, due to several unknowns. If the direction of crack propagation can be computed by means of one of the existing criteria, it is not known whether this direction will remain constant during crack propagation. A crack initiation leads to an enhanced stress field at crack tip. During propagation, the enhanced tip stress field propagates into the solid, locally interacting with the pre-existing stress field. This interaction can lead to modifications of the propagation direction, depending on the domain and crack geometry. Moreover, trajectory… More >

  • Open Access

    ARTICLE

    A Matrix Decomposition MFS Algorithm for Biharmonic Problems in Annular Domains

    T. Tsangaris1, Y.–S. Smyrlis1, 2, A. Karageorghis1, 2

    CMC-Computers, Materials & Continua, Vol.1, No.3, pp. 245-258, 2004, DOI:10.3970/cmc.2004.001.245

    Abstract The Method of Fundamental Solutions (MFS) is a boundary-type method for the solution of certain elliptic boundary value problems. In this work, we develop an efficient matrix decomposition MFS algorithm for the solution of biharmonic problems in annular domains. The circulant structure of the matrices involved in the MFS discretization is exploited by using Fast Fourier Transforms. The algorithm is tested numerically on several examples. More >

  • Open Access

    ARTICLE

    Agrobacterium rhizogenes vs auxinic induction for in vitro rhizogenesis of Prosopis chilensis and Nothofagus alpina

    LUIS A. CARO1, NATALIA SANTECCHIA1, PABLO A. MARINANGELI1, NÉSTOR R. CURVETTO1,2, LUIS F. HERNÁNDEZ1,3

    BIOCELL, Vol.27, No.3, pp. 311-318, 2003, DOI:10.32604/biocell.2003.27.311

    Abstract The induction and improvement of in vitro rhizogenesis of microshoots of Prosopis chilensis (Mol.) Stuntz and Nothofagus alpina (Poep. et Endl. Oerst.) were compared using Agrobacterium rhizogenes (Ar) versus indole-3-butyric acid (IBA) in the culture media. Microshoots of P. chilensis (1-2 cm length), coming from in vitro grown seedlings, were cultivated in a modified Broadleaved Tree Medium (BTMm) containing half salt concentration of macronutrients and 0.05 mg.L-1 benzilaminopurine (BAP). After 30 days, microshoots with 2-4 leaves were selected and cultured in BTMm-agar in presence or abscense of Ar and in combination with IBA. For N. alpina, the apical shoots with the first 2 true… More >

  • Open Access

    ARTICLE

    Interaction of bifidobacteria with the gut and their influence in the immune function

    Gabriela Perdigón1,2, Mónica Locascio1, Marta Medici1, Aida Pesce de Ruiz Holagado1,2, Guillermo Oliver1

    BIOCELL, Vol.27, No.1, pp. 1-9, 2003, DOI:10.32604/biocell.2003.27.001

    Abstract Bifidobacteria are predominant in the lumen of the large intestine and confer various health benefits on the host. They are also used in the preparation of new fermented milks (bioyogurts) or added to conventional yogurt to generate probiotic effects. The colonization of the gut by bacteria tends to be host specific due partly to the way in which bacteria adhere to the intestinal wall. Using a homologous strain of Bifidobacterium animalis in an experimental mouse model, we analyzed by immunofluorescence labelledbacteria and transmission electronic microscopy the importance of this bacterial interaction with epithelial an immune cells… More >

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