Broadband Müller-MLFMA for Electromagnetic Scattering by Dielectric Objects

The multilevel fast multipole algorithm (MLFMA) is very efficient for solving large-scale electromagnetic scattering problems. However, at low frequencies, or when the discretization is small compared with the wavelength, both the MLFMA and the underlying integral equation formulation typically suffer from a subwavelength breakdown. For the electromagnetic scattering from a homogeneous dielectric object, we obtain a stable and well-conditioned surface integral formulation using a variant of the classical Muumlller formulation and linear basis functions. To overcome the subwavelength breakdown of the MLFMA, we use both propagating and evanescent plane waves to represent the fields. The implementation is based on a combination of the spectral representation of the Green's function and Rokhlin's translation formula. We also present a new interpolation scheme for the evanescent part, which significantly improves the error-controllability of the MLFMA-implementation. Several numerical results verify both the error-controllability and scalability of the proposed algorithm     

Polarizabilities of platonic solids

This article presents results of a numerical effort to determine the dielectric polarizabilities of the five regular polyhedra: tetrahedron, cube, octahedron, dodecahedron, and icosahedron. The polarizability is calculated by solving a surface integral equation, in which the unknown potential is expanded using third-order basis functions. The resulting polarizabilities are accurate to the order of 10/sup -4/. Approximation formulas are given for the polarizabilities as functions of permittivity. Among other results, it is found that the polarizability of a regular polyhedron correlates more strongly with the number of edges than with the number of faces, vertices, or the solid angle seen from a vertex.     

Managing the Paradoxes of Mobile Technology

This article reports on a large-scale, international focus group study that examined the experiences of mobile technology users in Hong Kong, Japan, Finland, and the United States. It identifies eight central mobile technology paradoxes that shape user experience and behavior, suggests possible design features that relate to the experienced paradoxes, and discusses how these features could be better managed.     

Singularity subtraction technique for high-order polynomial vector basis functions on planar triangles

In this paper a singularity subtraction technique is developed for computing the impedance matrix elements of various electromagnetic surface integral equation formulations with the Galerkin method and high-order basis functions. Analytical closed form formulas for computing surface integrals with |r - r'|/sup n/, n/spl ges/-3, singularities times polynomial nodal shape functions of arbitrary order on a planar triangle are presented.