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The behavior of an electromagnetic wave impinging on a thin layer of arbitrary material can be described with a vector circuit interpretation of a transition matrix model. This paper follows the idea of applying such a matrix to the finit-element method (FEM). Especially, several very thin layers composed to an electrically not so thin layer may be treated comfortably. The method will be tested firstly on simple dielectric layer with a known analytic solution. In consequence, the example of a thick layer modeled by a number of thin layers will be given, as well. Index Terms--Bluetooth, coupled network boundary conditions, finite elements, thin layer, transition matrix.

Multiobjective optimization of shielding devices for eddy-currents is studied using several fundamentally different optimization methods. To solve the binary optimization problem of finding an optimal topology of the magnetic shunts a micro-genetic algorithm is used. In order to perform a parameter optimization of a given topology in terms of its placement, evolutionary strategies are applied. Finally, the multiobjective mixed binary-real optimization problem, with respect to both the topology and position of the magnetic shunts, is defined and solved using the micro-genetic algorithm. The conflicting objectives of minimizing Ohmic losses in the shielded body along with minimizing the volume of the shunts' magnetic material are taken into account in two different approaches. On the one hand all objectives are transformed into a single scalar value using the method of weighted functions; on the other hand Pareto optimal solutions are evaluated and assessed. To ensure the reliability of the obtained solutions, the evaluation of the objective functions is based on the 2-D finite-element method eddy-current analysis using both self developed and commercial field solvers. Index Terms--Eddy currents, electromagnetic shielding, optimization, stochastic methods.

There is a strong requirement within industrial environment for software integrated solutions for the design based on optimization that present a design engineer with little or no experience in numerical modeling with the possibility of obtaining meaningful engineering results. The core idea is to provide the user with an interface where only geometrical, material, excitation, or global field quantities are present, hiding from him the details of both the finite-element method (FEM) solution part as well as the optimization itself. Thus, a design engineer will be able to work within an environment with which he is highly familiar, and concentrate on the engineering task instead of the numerical intricacies. To exemplify, we have chosen a simple device, developed a driving application for the FEM field solver, identified meaningful parameters and then searched for suitable optimization procedures that we then coupled with the driving application. Index Terms--Evolution strategies, finite-element method (FEM) solver, microgenetic algorithms, optimization, software integrated solution.

Surface impedance boundary conditions (SIBCs) are used for analysis of a wide range of practical applications such as micro strips, transformers or electrical machines. In this work the SIBC was implemented with classical edge elements using the magnetic vector potential. As known, the SIBC is afflicted with errors when it is being used on curved surfaces and near corners and edges. For this reason this paper investigates the error of the SIBC on curved surfaces. Therefore, simulations have been carried out for different radii and frequencies. The simulation results of the SIBC formulation have been compared with the common A, V--[PHI] formulation for eddy current regions. It will be shown, that the error of the SIBC depends on the relation of the radius to the skin depth. Results are presented and discussed by means of a canonical problem. Index Terms--Approximate boundary conditions, curved surfaces, finite element methods, skin effect, surface impedance boundary conditions.

Modern design of medium-voltage switchgear insulation elements is based upon the use of optimization methods. This paper presents an algorithm for the design of such elements using numerical calculations on the basis of the finite elements method in connection with evolution optimization methods. The use of differential evolution and evolution strategy algorithms is presented in the case of modeling a medium-voltage post insulator, the secondary function of which is voltage indication. A comparison between these two algorithms is also presented. The task of both optimization algorithms is to find an adequate capacitance of the voltage divider and the optimal distribution of electric field strength. All other requirements and constraints that have to be taken into consideration in the design of insulation elements are also included in the algorithm. Index Terms--Finite-element method (FEM), high-voltage techniques, optimization methods, switchgear.

In electrical impedance tomography, an inverse problem has to be solved to reconstruct the complex conductivity distribution [kappa] = [sigma] + j[omega][epsilon]. The problem is ill posed, and therefore, a regularization has to be used. The aim is to reconstruct, as accurately as possible, both the electric conductivity [sigma] and the electric permittivity [epsilon] in three dimensions using finite elements of the second order for solving the forward problem. To this end, a new reconstruction algorithm based on a priori information has been developed. Index Terms--Complex conductivity, electrical impedance tomography (EIT).

Numerical optimization techniques are widely used for the design of electromagnetic devices. In practical implementations of such devices, the problem parameters may be subject to tolerances and uncertainties. Optimal designs should be insensitive to parameter variations. The demand for robustness is often neglected during the optimization process. A formulation of robust nonlinear design problems is proposed in this paper. The influence of uncertainties on the target performance and the feasibility of a solution is assessed and incorporated into the optimization strategy. Methods for the solution of robust problems are introduced. Special emphasis is put on keeping the computational effort as small as possible. The proposed robust optimization method is applied to a standard benchmark optimization problem. Index Terms--Electromagnetic design, robust optimization, TEAM problem, worst case design.

Magnetic induction tomography of biological tissue is used for reconstructing the conductivity distribution [kappa] = [sigma] + j[omega][epsilon] or changes [DELTA][kappa] in a human body by measuring the perturbation AB of an alternating magnetic field [B.sub.o]. The aim is to simulate the eddy current problem in magnetic induction tomography for biomedical applications by symmetric tetrahedral edge finite elements of second order. The method is validated by measurement data from a representative experiment, and numerical results of an edema in a human head are presented. Index Terms--Eddy current problem, magnetic induction tomography, sensitivity, symmetric tetrahedral edge elements of second order.

This paper gives an overview of some stochastic optimization strategies, namely, evolution strategies, genetic algorithms, and simulated annealing, and how these methods can be applied to problems in electrical engineering. Since these methods usually require a careful tuning of the parameters which control the behavior of the strategies (strategy parameters), significant features of the algorithms implemented by the authors are presented. An analytical comparison among them is performed. Finally, results are discussed on three optimization problems. Index Terms - Finite element method, magnetic analysis, optimization methods.

Near Field Communication (NFC) techniques are widely used within everyday activities, e.g., contactless payment systems or authentication. Regardless of the application typically the requirements on the antenna structure are manifold. Frequently limitations in the available space make the antenna design quite challenging especially if other conductive structures are close to the NFC antenna. In the present paper we propose to synthesize the geometry of proximity integrated circuit card (PICC) antennas according to class 6 in the presence of nearby metallic structures. The optimization relies on the differential evolution strategy. The computation of the forward problem is based on the partial element equivalent circuit (PEEC) method. [ABSTRACT FROM AUTHOR]

Wireless communication technologies such as Near Field Communication (NFC) found its way into our everyday life. The antenna structures used in such systems have to comply with several standards to achieve all requirements defined for the specific application. However, in practice there are scenarios for such antennas which are not considered in standards or design guides, but mainly influence the antenna behavior. In the present paper the synthesis of an antenna used for NFC-cards in a contactless payment system under multi-card condition is presented. The optimization relies on the differential evolution (DE) strategy. The computation of the forward problem is based on the partial element equivalent circuit (PEEC) method. [ABSTRACT FROM AUTHOR]

We consider a nonlinear magnetostatic field problem, where in a certain subdomain a cost functional (i.e., the magnetic field has to fulfill a prescribed figure) is defined. The optimization problem is stated in such a way that the field problem is treated as a constraint. A Lagrange function is established depending on the magnetic vector potential A, the current density J in coil segments and the vector of Lagrange multipliers [lambda]. The derivatives with respect to the variables are set to zero to obtain the optimality system. The optimality system is solved applying full Newton steps without line search. For the left hand side of the Newton system the second derivatives of the Lagrange function are required while the first derivatives of the Lagrange function are written into the right hand side. Employing a finite element scheme to discretize the problem domain, we end up with a linear system of equations that has to be solved for each Newton step. Index Terms--Magnetostatics, Newton method, nonlinear magnetics, optimization methods.