Composite grid method for analysis of electromagnetic field

In this paper, a composite grid method (CGM) for finite element (FE) analysisof an electromagnetic field with strong local interest is proposed. The method is based on theregular finite element method in conjunction with three basic steps, i.e. global analysis, localanalysis, and modified global analysis. In the first two steps, a coarse finite element mesh is usedto analyze the global model to obtain the nodal potentials which are subsequently used asartificial boundary conditions for local regions of interest. These local regions with theprescribed boundary conditions are then analyzed with refined meshes to obtain more accuratepotential and density distribution In the third step, a modified global analysis is performed toobtain more improved solution for potential and density distribution. And iteratively, successivelyimproved solutions can be obtained until the desired accuracy is achieved. Various numericalexperiments show that CCM yields accurate solutions with significant savings in computing timecompared with the regular finite element method.

A PRECONDITIONER FOR COUPLING SYSTEM OF NATURAL BOUNDARY ELEMENT AND COMPOSITE GRID FINITE ELEMENT

Discusses a coupling boundary element methods with finite element method for the Dirichlet exterior problems. Information on the natural boundary reduction; Discussion on the composite grid discretization; Details on a preconditioner for the discrete system.

Mechanical properties of lattice grid composites

An equivalent continuum method only considering the stretching deformation of struts was used to study the in-plane stiffness and strength of planar lattice grid com- posite materials. The initial yield equations of lattices were deduced. Initial yield surfaces were depicted separately in different 3D and 2D stress spaces. The failure envelope is a polyhedron in 3D spaces and a polygon in 2D spaces. Each plane or line of the failure envelope is corresponding to the yield or buckling of a typical bar row. For lattices with more than three bar rows, subsequent yield of the other bar row after initial yield made the lattice achieve greater limit strength. The importance of the buckling strength of the grids was strengthened while the grids were relative sparse. The integration model of the method was used to study the nonlinear mechanical properties of strain hardening grids. It was shown that the integration equation could accurately model the complete stress-strain curves of the grids within small deformations.

Mechanical properties of lattice grid composites

Unfortunately, an error occurred in Fig. 12. The corrected Fig. 12 is given below.

Grid architecture model of network centric warfare

NCW(network centric warfare) is an information warfare concentrating on network. A global network-centric warfare architecture with OGSA grid technology is put forward,which is a four levels system including the user level, the application level, the grid middleware layer and the resource level. In grid middleware layer,based on virtual hosting environment, a BEPL4WS grid service composition method is introduced. In addition, the NCW grid service model is built with the help of Eclipse-SDK-3.0.1 and Bpws4j.

Object-oriented software tools for parallel PDE solvers

An object-oriented approach is taken to the problem of formulating portable, easy-to-modify PDE solvers for realistic problems in three space dimensions. The resulting software library, Cogito, contains tools for writing programs to be executed on MIMD computers with distributed memory. Difference methods on composite, structured grids are supported. Most of the Cogito classes have been implemented in Fortran 77, in such a way that the object-oriented design is visible. With respect to parallel performance, these tools yield code that is comparable to parallel solvers written in plain Fortran 77. The resulting programs are can be executed without modification on a large number of multicomputer platforms, and also on serial computers. The uppermost level of abstraction in Cogito concerns the problem of decoupling the numerical method from the PDE problem. The validity of these tools has been preliminarily demonstrated with a C++ implementation for one-dimensional problems.

A Three-dimensional Heterogeneous Mass Transfer Model for the Absorption of Gas into Multiphase System

A three-dimensional heterogeneous mass transfer model was proposed to investigate the enhancement of dispersed particles on gas absorption. The strategy to calculate local and overall enhancement factors is proposed. Instead of a global grid, the composite overlapping grid is adopted, which simplifies the setup and solution of the three-dimensional model equations. It is found that dispersed particle hold-up, particle size, liquid-solid partition coefficient of transported component, characteristic contact time, and the shortest distance between particles and gas-liquid interface have major influence on absorption enhancement factor. The particle-particle interaction on gas absorption and the lateral diffusion of transported component in liquid film were studied with the multi-particle simulation. The proposed model predicted the experimental data from the literature reasonably well.