International Journal of Applied Electromagnetics and Mechanics

The scalar Hertz potential technique is applied to the field analysis in uniaxial dielectric -- magnetic mediums. These mediums may be either homogeneous or nonhomogeneous (with a nonhomogeneity of a restricted form). It is shown that the complete electromagnetic field in a uniaxial dielectric -- magnetic medium can be derived from two scalar Hertz potentials(plus, for certain types of problems, a small number of source -- specific auxiliary functions). The corresponding scalar Green functions are explicitly given for the homogenous case and applications for radiation and propagation problems are presented.

This paper presents a new approach for reducing the computational cost needed to solve the forward problem, i.e. the prediction of the measurements of a given ECT measurement system. This issue is mandatory in any inversion algorithm which, typically, requires the solution of a large number of direct problems.

Integral formulations are attractive for ECT since they require the discretization of the conductive body only. However they also give rise to a full stiffness matrix whose inversion, typically obtained using direct solvers, has a computational cost that grows as O(n^3) where n is the number of unknowns arising from the discretization. Iterative algorithms achieve a computational cost that is lower than direct solvers when the stiffness matrix is sparse.

The approach proposed in this paper makes it possible to represent the stiffness matrix arising from an edge-elements based integral formulation, by means of the Fast Fourier Transform. This representation is achieved for bounded conductive domains meshed by a regular mesh and incurs a computational cost that grows as O(N \log h) .

In this paper, homogenized dielectric constitutive equations for heterogeneous materials characterized by a random arrangement of the inclusions are obtained. The homogenization problem is formulated by using the Hashin and Shtrikman variational principle and by considering macroscopic charge density. The solution of the homogenization problem is obtained both in the Fourier and in the space domain. Explicit expressions of homogenized constitutive equations are presented for statistically homogeneous two-phase composites in terms of the two point correlation functions of the inclusions. These functions are deduced for a special class of heterogeneous materials reinforced by square or rectangular fibres whose arrangement is generated from the probability density function (p.d.f.) of the centres of the inclusions. At this aim, an efficient procedure to obtain the two-point correlation functions from the p.d.f. of the centres is proposed. Finally, several examples of overall constitutive equations are developed both for periodic and for random composites and comparisons with exact results for laminates are presented.

In this paper a simplified method for the characterization of magnetic media used as magnetic stripes on identification cards and tickets is described. It is based on standard measuring procedures but provides the advantage of less calibration work and a minimum set of measurements and calculations.

The purpose of this work is to present a general formulation of the static, linear plane strain problem of uncoupled thermo-magnetoelasticity for isotropic media occupying simply connected regions, based on the combined use of the stress function and of the boundary integral representation technique in terms of real functions.

A new representation of the mechanical displacement vector is deduced, which makes it possible to reach a complete solution to the problem within the proposed formulation. It is assumed that the electric current inside the body has constant density. Different thermal and mechanical boundary conditions are considered. A simple application for the circular cylinder carrying a steady axial current is solved and the results are analyzed and compared to those existing in the literature. The obtained formulae for this case allow the determination of two material constants through careful measurements of the radial mechanical displacement and the transversal stress component at the surface of the conductor.