Ultra-wide band antennas can be characterized by the time-domain impulse response. This paper introduces an approximate form of the impulse response that can be calculated by applying the method of moments to the Freedholm integral equation of convolution. Numerical results are compared to those obtained using the traditional frequency-domain approach. The validity of the approximate impulse response and the application constraints are also discussed. It is shown that the time-domain approach is faster than the frequency-domain approach while the accuracy is preserved.

This paper proposes a general applicable numericalalgorithm for the simulation of two dimensional electrode shapechanges during electroforming processes. The computational modelconsists of two coupled problems: electrode shape change ratecomputation and a moving boundary problem. The innovative aspect isthat the electrode shape is computed over a number of predefinedtime steps by convection of its surface proportional with and in thedirection of the local growth rate. Validation of the electrodegrowth algorithm is made by comparison with experimental resultsobtained for the electrode growth in the vicinity of a singularity(incident angle between the electrode and insulator = 180°).Finally an example related to the plating of two adjacent wires inorder to demonstrate the strong features of the applied method willbe presented.

The generalized Mie theory, also known as themultiple-scattering theory, is an analytical method for solving the scattered field by a collection of spherical scatterers. This is the fastest, most reliable method when the wavelength is close to the structure's dimensions. It is applicable to frequency selective surfaces and is the onlymethod for analyzing finite photonic crystals with a large size. We used simplified structures to compare this method with other techniques.

Induction motors optimal design can involve many variables and objectives, and generally requires to make several trade-offs, especially when including the audible electromagnetic noise criterion beyond the usual performance criteria. Multiobjective optimization techniques based on Pareto optimality are useful to help us finding the most interesting solutions and decide which one(s) to adopt. However, it is not always easy to analyse the Pareto-optimal solutions obtained with such methods, especially when treating more than three objectives, and Pareto fronts may contain more data than we might think.This paper briefly describes an analytical model of the variable-speed squirrel-cage induction machine which computes both its performances and sound power level of electromagnetic origin. The model is then coupled to the Non-dominated Sorting Genetic Algorithm (NSGA-II) in order to perform global optimization with respect to several objectives (e.g. noise level, efficiency and material cost). Finally, an optimization problem is solved and analysed, and some useful visualization tools of the Pareto optimal solutions and their characteristics are presented.

The shielding of strong electromagnetic fields at power frequency, performed by ferromagnetic plates, is often successfully modelled by the effective reluctivity. This method delivers good results for the RMS value of the shielded field. The following paper shows that a small variation of the magnetization curve (e.g. by taking another material charge) can strongly influence the shielded field. The field calculation is performed by the Finite Element Method (FEM), where for the interior plate region a) finite elements and b) non-linear Impedance Boundary Conditions (IBC) are used which circumvents the need to discretize the shielding plate.

This paper presents the application of a homogenisationtechnique, based on the multi-scale expansion theory, to theanalysis of heterogeneous materials constituted of magneticinclusions dispersed in a dielectric lattice. The role of the shapeand dimensions of the inclusions is analysed with reference to theeffective electromagnetic properties and energy losses. Theinvestigation is extended to the influence of flux waveforms withharmonic distortion, focusing the attention on the energy lossdependency on the harmonic content.

For designers, calculation of local fluxes can be very useful. Inthe vector potential formulation, the local fluxes can be easilydeduced. In the scalar potential formulation, the determination ofthese fluxes presents some difficulties. In this paper, we presentthree methods to compute a flux through any surface in the scalarpotential formulation. These are compared with the one used in thevector potential formulation for two application examples.

In this paper, we present a modeling of a captured ferromagnetic particles quantifying method based on the detection and evaluation of the magnetic field variation caused by the particle static buildup. The detecting element is a Hall-effect sensor (probe) associated to the particle capture element which is an electromagnet with iron core. From a known value of the magnetic field measured at the particle static buildup locality, we predict the particle global concentration in the treated material sample (powder or liquid). This prediction is achieved by solving the inverse problem for the captured particles magnetic field variation. Such a resolution is based on an iterative resolution of the forward problem until obtaining the global particle concentration related to the measured value of the field variation. Because an exact value can not be obtained we retain the value that minimizes an error function. To minimize such a function we have used the Tabu searching method.

We introduce pairing matrices on simplicial cell complexes in discrete electromagnetism as a means to avoid the explicit construction of a topologically dual complex. Interestingly, the Finite Element Method with first-order Whitney elements — when it is looked upon from a cell-method perspective — features pairing matrices and thus an implicitly defined dual mesh. We show that the pairing matrix can be used to construct discrete energy products. In this exercise we find that different formalisms lead to equivalent matrix representations. Discrete de Rham currents are an elegant way to subsume these geometrically equivalent but formally distinct ways of defining energy-products.

This paper compares the hybrid FEM-BEM and FEM-DBCImethods for the solution of open-boundary electrostatic fieldproblems. Both methods couple a differential equation for theinterior problem with an integral equation for the exterior one. Thecomparison shows that FEM-BEM is more accurate than FEM-DBCI butrequires more computing time.

The aim of this research is the elaboration of a method allowing simple simulation of electromagnetic interferences (EMI) of complex electric systems. The method presented in this paper allows the replacement of the electromagnetic active objects by simple closed surfaces that surround each source. The flux density components are calculated on these surfaces using standard 3D finite element software separately for each object. The magnetic flux density in every point of the free space around the system is calculated with an analytical formula. The main topic of the paper is the definition of the limits of the discussed method.

Steady-state operation modes of three-phase induction machines canbe efficiently simulated by 2D nonlinear time-harmonic finite-element models, although only induced currents with respect to the fundamental air-gap field are correctly taken into account.This technique does not generalise to single-phase inductionmachines. An approach based on multiple rotor models and a spectraldecomposition of the air-gap field enables to consider higherharmonic air-gap field contributions. In a capacitor-motor model,the first, third and fifth forward and backward rotating componentsgive raise to different frequencies in the rotor which result indifferent eddy-current effects. The torque dip due to the thirdharmonic is accurately simulated.

In this paper, differential conductivity and reluctivity matricesare constructed for formulations discretised by the finiteintegration technique and linearised by the Newton method. It turnsout that these matrices are nondiagonal and unsymmetric, even in thecase that orthogonal grids are used. A diagonal approximation of thedifferential matrices leads to an approximate Newton method wherecross-magnetisation effects are no longer considered, except in theupdate between the successive nonlinear iteration steps. The approximate method does not guarantee second order convergence but outperforms the true Newton method when only a moderate accuracy is required.

The spectroscopic electrical characterization of biological tissues between 10 Hz and 10 MHz is generally based on four-electrode impedance measurement. An array of four aligned needle-electrodes is commonly used for the probe. The electrode/sample interface impedances and the parasitic capacitances of the system induce measurement inaccuracies respectively in the low and high parts of the studied frequency range. These inaccuracies cannot be removed by any usual calibration method but can be minimized by modifying the geometry of the probe. Using a 3D finite element model of the probe coupled with a deterministic optimization algorithm, it is shown that the configuration of the electrodes should be different at 10 Hz and 10 MHz to improve the performances of the measurement system.

The computation of induced currents in a conductor whose shape isa dome is achieved iteratively by dividing this conductor intoseveral elementary layers to take into account the tridimensionalbehaviour of the induced currents.

This study deals with the wall characterization of a glass furnace based on an electrical resistance measurement between two buried electrodes. The relationship between the wall geometry and the electrical resistance is established. This paper presents the modelling aspects of this inspection technique.

A dynamical model of a deformable circuit submitted to an induction source is described in infinite dimension and in its discrete version. One explains in particular how to practically carryout the calculation of the inductance of the circuit, which is one necessary condition to obtain an exploitable model.

In this paper, a coupled magneto-mechanical finite-element model is briefly presented and then used to determine the different electromagnetical strains of a structure mechanically closed to a single-phase stator of a switched reluctance motor. Magnitudes of the magnetostrictive forces and of the magnetic forces, such as their relative importance in the structure strain, are given for different current excitations.

The aim of this study is to determine the complex permittivity of dielectric materials using a coaxial discontinuity and the combination of neural networks (NN) with the finite element method. Two types of measurement cells are used. One is for solid samples and the other one for liquids. Data sets used to train neural networks are created using the finite element method. The number of hidden neurons of the NN is determined by the split-sample method. The designed NN are used for the estimation of the permittivity of several materials and their results compared with the ones obtained with a gradient inversion method.