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On Nonreflecting Boundary Conditions
 J. COMPUT. PHYS
, 1995
"... Improvements are made in nonreflecting boundary conditions at artificial boundaries for use with the Helmholtz equation. First, it is shown how to remove the difficulties that arise when the exact DtN (DirichlettoNeumann) condition is truncated for use in computation, by modifying the truncated ..."
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Cited by 219 (4 self)
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Improvements are made in nonreflecting boundary conditions at artificial boundaries for use with the Helmholtz equation. First, it is shown how to remove the difficulties that arise when the exact DtN (DirichlettoNeumann) condition is truncated for use in computation, by modifying the truncated condition. Second, the exact DtN boundary condition is derived for elliptic and spheroidal coordinates. Third, approximate local boundary conditions are derived for these coordinates. Fourth, the truncated DtN condition in elliptic and spheroidal coordinates is modified to remove difficulties. Fifth, a sequence of new and more accurate local boundary conditions is derived for polar coordinates in two dimensions. Numerical results are presented to demonstrate the usefulness of these improvements.
Fast Solution Methods in Electromagnetics
, 1997
"... Various methods for efficiently solving electromagnetic problems are presented. Electromagnetic scattering problems can be roughly classified into surface and volume problems, while fast methods are either differential or integral equation based. The resultant systems of linear equations are either ..."
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Cited by 33 (0 self)
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Various methods for efficiently solving electromagnetic problems are presented. Electromagnetic scattering problems can be roughly classified into surface and volume problems, while fast methods are either differential or integral equation based. The resultant systems of linear equations are either solved directly or iteratively. A review of various differential equation solvers, their complexities, and memory requirements is given. The issues of grid dispersion and hybridization with integral equation solvers are discussed. Several fast integral equation solvers for surface and volume scatterers are presented. These solvers have reduced computational complexities and memory requirements. 1. Introduction Computational electromagnetics is a fascinating discipline that has drawn the attention of mathematicians, engineers, physicists, and computer scientists alike. It is a discipline that creates a symbiotic marriage between mathematics, physics, computer science, and various applicatio...
A Hybrid Symmetric FEM/MOM Formulation Applied to Scattering by Inhomogeneous Bodies of Revolution
"... A new symmetric formulation of the Hybrid Finite Element Method(HFEM) is described which combines elements of the Electric Field Integral Equation (EFIE) and the Magnetic Field Integral Equation (MFIE) for the exterior region along with the finite element solution for the interior problem. The formu ..."
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Cited by 7 (0 self)
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A new symmetric formulation of the Hybrid Finite Element Method(HFEM) is described which combines elements of the Electric Field Integral Equation (EFIE) and the Magnetic Field Integral Equation (MFIE) for the exterior region along with the finite element solution for the interior problem. The formulation is applied to scattering by inhomogeneous bodies of revolution. To avoid spurious modes in the interior region a combination of vector and nodal based finite elements are used. Integral equations in the exterior region are used to enforce the Sommerfield radiation condition by matching both the tangential electric and magnetic fields between interior and exterior regions. Results from this symmetric formulation as well as formulations based soley on the EFIE or MFIE are compared to exact series solutions and integral equation solutions for a number of examples. The behavior of the symmetric, EFIE, and MFIE solutions is examined at potential resonant frequencies of the interior and ext...
An Eigenvalue Hybrid Fem Formulation for 2d Open Structures Using Mixed Type Node/edge Elements and a Cylindrical Harmonics Expansion,” PIERS
, 2004
"... Abstract A Finite element formulation for the solution of the twodimensional eigenvalue problem for open radiating structures is proposed. The semiinfinite solution domain that occurs in such problem is modelled using an expansion in an infinite sum of cylindrical harmonics, while the structure i ..."
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Cited by 1 (1 self)
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Abstract A Finite element formulation for the solution of the twodimensional eigenvalue problem for open radiating structures is proposed. The semiinfinite solution domain that occurs in such problem is modelled using an expansion in an infinite sum of cylindrical harmonics, while the structure itself is described by the finite element method. The two mathematical models are coupled by exploiting the tangential field continuity condition. In fact for the truncation of the finite element mesh a fictitious cylindrical domain boundary is used which encloses the opening of our structure. On that fictitious boundary we impose the field continuity condition formulating in that way a generalized eigenvalue problem taking in to account Sommerfeld radiation condition. This final eigenvalue problem is solved using the Arnoldi subspace iterative technique,
Paired Pulse Basis Functions and Triangular Patch Modeling for the Method of Moments Calculation of Electromagnetic Scattering from ThreeDimensional, ArbitrarilyShaped Bodies
, 2008
"... Except where reference is made to the work of others, the work described in this dissertation is my own or was done in collaboration with my advisory committee. This dissertation does not include proprietary or classified information. ..."
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Except where reference is made to the work of others, the work described in this dissertation is my own or was done in collaboration with my advisory committee. This dissertation does not include proprietary or classified information.
Numerical Implementation of a Conformable TwoDimensional Radiation Boundary Condition
, 1995
"... In open region differential equation problems it is common to limit the computational domain by introducing an artificial boundary. The artifical boundary condition must be chosen to produce as little reflection as possible. Numerous ideas have been employed in the search of accurate and efficient r ..."
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In open region differential equation problems it is common to limit the computational domain by introducing an artificial boundary. The artifical boundary condition must be chosen to produce as little reflection as possible. Numerous ideas have been employed in the search of accurate and efficient radiation boundary conditions (RBCs). A finite element method (FEM) formulation that encompasses many different RBCs is presented. The computational domain can be a general convex twodimensional domain containing the scatterer. The resulting system of linear equations is sparse and, in general, nonHermitian. Examples using a generalization of the second order Bayliss Turkel RBC with both circular and noncircular artificial boundaries are also discussed. The results from these tests both validate the present computational system and illustrate some of the computational savings (time and memory) that can be obtained by selecting an artificial boundary conformal with the scatterer.
Electromagnetic Scattering by Arbitrary Shaped ThreeDimensional Homogeneous Lossy Dielectric Objects
"... AbstractThe recent development and extension of the method of moments technique for analyzing electromagnetic scattering by arbitrary shaped threedimensional homogeneous lossy dielectric objects is presented based on the combined field integral equations. The surfaces of the homogeneous threedim ..."
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AbstractThe recent development and extension of the method of moments technique for analyzing electromagnetic scattering by arbitrary shaped threedimensional homogeneous lossy dielectric objects is presented based on the combined field integral equations. The surfaces of the homogeneous threedimensional arbitrary geometrical shapes are modeled using surface triangular patches, similar to the case of arbitrary shaped conducting objects. Further, the development and extensions required to treat efficiently threedimensional lossy dielectric objects are reported. Numerical results and their comparisons are also presented for two canonical dielectric scatterersa sphere and a finite circular cylinder. T I.
[1,2]. These conditions were implemented in the context of Maxwells equations and the Navier–Stokes
"... equations by Mur [3], Rudy and Strikwerda [4], respectively. Bayliss and Turkel [5–8] developed an ..."
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equations by Mur [3], Rudy and Strikwerda [4], respectively. Bayliss and Turkel [5–8] developed an
Item type text; DissertationReproduction (electronic)
"... Infants ' expectations about the spatial and physical properties of ..."
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