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Force Method (force + method)

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Engineering100%

Selected Abstracts

Efficient graph-theoretical force method for two-dimensional rectangular finite element analysis

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 9 2009
A. Kaveh
Abstract In this paper an efficient method is developed for the formation of null bases of finite element models (FEMs) consisting of rectangular plane stress and plane strain elements, corresponding to highly sparse and banded flexibility matrices. This is achieved by associating special graphs with the FEM and selecting appropriate subgraphs and forming the self-stress systems on these subgraphs. The efficiency of the present method is illustrated through three examples. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Minimal cycle basis of graph products for the force method of frame analysis

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 8 2008
A. Kaveh
Abstract For an efficient force method of frame analysis, the formation of localized self-equilibrating systems is an important issue. Such systems can be constructed on minimal cycle basis of the graph model of the structure. In this paper, algorithms are presented for the formation of minimal cycle bases of graph products corresponding to sparse cycle adjacency matrices, leading to the formation of highly sparse flexibility matrices. The algorithms presented employ concepts from three graph products namely Cartesian, strong Cartesian and lexicographic products. Though the formulation for the first two products exist, however, efficient implementations are made in this paper. The formulation for the generation of minimal cycle basis is extended to the lexicographic product. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Subminimal cycle basis of a graph for efficient force method of frame analysis

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 11 2005
A. Kaveh
Abstract A new method is presented for the formation of subminimal cycle bases of graphs corresponding to sparse flexibility matrices. In this approach, a Contraction method is used, leading to the reduction of the size of the graph at each step. This reduction facilitates the selection of the smallest cycle at subsequent steps. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Numerical simulation of bubble and droplet deformation by a level set approach with surface tension in three dimensions

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 9 2010
Roberto Croce
Abstract In this paper we present a three-dimensional Navier,Stokes solver for incompressible two-phase flow problems with surface tension and apply the proposed scheme to the simulation of bubble and droplet deformation. One of the main concerns of this study is the impact of surface tension and its discretization on the overall convergence behavior and conservation properties. Our approach employs a standard finite difference/finite volume discretization on uniform Cartesian staggered grids and uses Chorin's projection approach. The free surface between the two fluid phases is tracked with a level set (LS) technique. Here, the interface conditions are implicitly incorporated into the momentum equations by the continuum surface force method. Surface tension is evaluated using a smoothed delta function and a third-order interpolation. The problem of mass conservation for the two phases is treated by a reinitialization of the LS function employing a regularized signum function and a global fixed point iteration. All convective terms are discretized by a WENO scheme of fifth order. Altogether, our approach exhibits a second-order convergence away from the free surface. The discretization of surface tension requires a smoothing scheme near the free surface, which leads to a first-order convergence in the smoothing region. We discuss the details of the proposed numerical scheme and present the results of several numerical experiments concerning mass conservation, convergence of curvature, and the application of our solver to the simulation of two rising bubble problems, one with small and one with large jumps in material parameters, and the simulation of a droplet deformation due to a shear flow in three space dimensions. Furthermore, we compare our three-dimensional results with those of quasi-two-dimensional and two-dimensional simulations. This comparison clearly shows the need for full three-dimensional simulations of droplet and bubble deformation to capture the correct physical behavior. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Miniaturized antenna using half-mode substrate integrated waveguide structure

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 12 2008
Cuilin Zhong
Abstract An X-band miniaturized antenna which uses half-mode substrate integrated waveguide structure is designed. We analyzed the electromagnetic field using the cavity model and the electromotive force method. The input impedance, simulated and experimental results of return loss, resonant frequency, and radiation patterns are presented. Its performances are as same as those of the corresponding microstrip antenna, but its size is half of the microstrip antenna. This planar structure can be integrated on the same substrate with other components such as filter and amplifier, and it can also be used to easily form antenna arrays. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 3214,3218, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23911 [source]