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This paper aims at detecting and characterizing inclusions in concrete structures by inverting ground-penetrating radar (GPR) data. First, the signal is preprocessed using the principal component analysis (PCA) and then used to train an artificial neural network (ANN). The GPR data consists of 1200 time steps. Using PCA, the data can be compressed to 286 dimensions without losing any information. Moreover, with 99.99% of the original variance the data needs only 139 dimensions. This dimensional reduction makes the ANN training easier and faster. The ANN were trained to find the buried inclusions characteristics--depth and radii--considering a nonhomogenous host medium by inverting the preprocessed data. The results show that the expected maximum error was kept under 1%, which is a remarkable result, since the host medium is nonhomogenous. Index Terms--Artificial neural network (ANN), buried objects, ground-penetrating radar (GPR), inverse problem.

This paper investigates the characterization of inclusions in concrete structures, including the number of inclusions, their geometries, and electromagnetic properties. To solve this problem, a two phase algorithm that combines matched-filter-based reverse-time (MFBRT) migration algorithm with the particle swarm optimization (PSO) is employed. The first phase runs the MFBRT that can, robustly, define the number of inclusions and their centers; however, it cannot define the inclusion geometry and electromagnetic properties. Given the results obtained in the first phase, the PSO is launched in the second phase, in a parametric approach, to define the radii of the inclusions and their properties. Three types of inclusions were considered, water, air, and conductor. Results considering a nonhomogenous host medium having from one to three inclusions are presented showing the effectiveness of the proposed approach. Index Terms--Finite-difference time domain (FDTD), inverse scattering, migration algorithms, particle swarm optimization.

An accurate method to compute dual field in high frequency time harmonic problem is presented. From a primal field obtained by a vector finite element discretization, the dual field is obtained without numerical derivation by using a least square argument. The accuracy of the method is compared with the natural method using shape function derivatives. Index Terms--Edge elements, finite element method, post-processing.

In this paper, common mode (CM) conducted perturbations are predicted and compared with experiments in a variable-speed drive system, thanks to a mixed approach based on experimental measurements and on the modeling of the complete CM circuit. Its different parts are considered and represented by a chain of quadripolar matrices: the inverter, the cables, and the induction motor. At last, it is shown that the parasitic currents in the system can be calculated in the different stages of the matrix chain. Experiments have successfully confirmed this approach. Index Terms--Conducted perturbations, quadripolar matrices modeling, variable-speed drive.

This paper deals with some aspects of performance of the symmetric successive over-relaxation preconditioner in a distributed environment. The details of distributed formulation of the preconditioner are presented. Some performance metrics are compared and discussed for the message passing interface implementation of the algorithm. The properties of the solver are estimated for concurrent three-dimensional formulation of the finite-element time-domain method. The analyzed benchmark models are approximated by tetrahedral first order Whitney elements. Index Terms--Edge elements, finite-element (FE) method, iterative solver, parallel numerical algorithms, time-domain algorithm.

This paper presents a three-dimensional computational model for nonlinear microwave heating problems. In order to reduce the computational costs, a new finite element method adaptive time-stepping scheme is proposed. Numerical results are compared with experimental measurements on a problem of dielectric heating of water. Index Terms--Adaptive time-stepping, finite element method (FEM), microwave heating, nonlinear dielectric properties.

Properties of the three-dimensional formulation of the finite element time domain algorithm for the wave equation are analyzed. First-order edge elements are implemented in the formulation. Several issues associated with deformation of the structured mesh and efficiency of the time integration scheme are presented. The convergence and stability of the time domain algorithm depending on the spatial discretization are discussed. The numerical accuracy of the simulation is studied. Index Terms--Edge elements, finite element method, stability, time domain analysis.

A procedure to optimize the specific absorption rate deposed in the patient during oncology hyperthermia treatment is presented. It is based on a genetic algorithm coupled to a finite-element formulation. The optimization procedure is applied to a real human body obtained from computerized tomography scans. Index Terms--Electromagnetic fields, finite-element methods, genetic algorithms, hyperthermia.

This paper deals with a distributed time-domain modeling of electromagnetic phenomena with the finite-element method. The model is approximated by edge elements. The constitutive equations and method of parallelization of the algorithm are presented. The properties Of the distributed finite-element time-domain algorithm are discussed. Some typical performance metrics are studied for the parallel versions of the software. The presented algorithm is executed on a heterogeneous and a homogeneous clusters of workstations. Two different distributed memory environments (MPI and PVM) are used to evaluate the efficiency of the algorithm. Index Terms--Distributed computing, edge elements, finite-element time-domain (FETD) algorithm, high-frequency electromagnetic field.

The boundary integral method is used to solve scattering by perfect electric conducting or perfect dielectric bodies. This paper deals with different aspects of the modeling: frequency domain and time domain formulations, computing, solver. Methods allowing the treatment of geometrical discontinuity for all kinds of mesh are specially discussed. Validation of the formulations is carried by comparison with other codes. Index Terms--Boundary element methods, discontinuities, numerical analysis.