A Combined Finite Element And Boundary Integral Formulation For Solution Via Cgfft Of 2 Dimensional Scattering Problems

A new technique is presented for computing the scattering by 2-D structures of arbitrary composition. The proposed solution approach combines the usual finite element method with the boundary integral equation to formulate a discrete system. This is subsequently solved via the conjugate gradient (CG) algorithm. A particular characteristic of the method is the use of rectangular boundaries to enclose the scatterer. Several of the resulting boundary integrals are therefore convolutions and may be evaluated via the fast Fourier transform (FFT) in the implementation of the CG algorithm. The solution approach offers the principle advantage of having O(N) memory demand and employs a 1-D FFT versus a 2-D FFT as required with a traditional implementation of the CGFFT algorithm. The speed of the proposed solution method is compared with that of the traditional CGFFT algorithm, and results for rectangular bodies are given and shown to be in excellent agreement with the moment method. Collins, Jeffery D. and Volakis, John L. Unspecified Center BOUNDARY INTEGRAL METHOD; FAST FOURIER TRANSFORMATIONS; FINITE ELEMENT METHOD; WAVE SCATTERING; ALGORITHMS; COMPUTATIONAL GRIDS; COMPUTER SYSTEMS PERFORMANCE; MEMORY (COMPUTERS); METHOD OF MOMENTS; WAVE EQUATIONS...

A method for the computation of electromagnetic scattering from arbitrary two-dimensional bodies is presented. The method combines the finite element and boundary element methods leading to a system for solution via the conjugate gradient Fast Fourier Transform (FFT) algorithm. Two forms of boundaries aimed at reducing the storage requirement of the boundary integral are investigated. It is shown that the boundary integral becomes convolutional when a circular enclosure is chosen, resulting in reduced storage requirement when the system is solved via the conjugate gradient FFT method. The same holds for the ogival enclosure, except that some of the boundary integrals are not convolutional and must be carefully treated to maintain O(N) memory requirement. Results for several circular and ogival structures are presented and shown to be in excellent agreement with those obtained by traditional methods. Collins, Jeffery D. and Jin, Jian-Ming and Volakis, John L. Unspecified Center...

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Volume 2 in this series offers research into two specific regions of the electromagnetic spectrum: extremely low frequency fields and radiofrequency radiation, with particular emphasis on the latter. The investigations explore: melatonin synthesis and exposure to extremely low frequency (ELF) fields ELF fields and cancer computational bioelectromagnetics health effects, including the carcinogenic potential of radiofrequency radiation radiofrequency radiation as an energy source for arrhythmia, and practical applications of the radiofrequency exposure standard.

finite number of steps. Moreover, since the CGFFT algorithm is highly vectorizable, it can be efficiently implemented on supercomputers and multiprocessor machines.