Detection, Location and Imaging of Multiple Scatterers by means of the Iterative Multiscaling Method

In this paper, a new version of the iterative multiscaling method (IMM) is proposed for reconstructing multiple scatterers in two-dimensional microwave imaging problems. The manuscript describes the new procedure evaluating the effectiveness of the IMM previously assessed for single object detection. Starting from inverse scattering integral equations, the problem is recast in a minimization one by defining iteratively (at each level of the scaling procedure) a suitable cost function allowing firstly a detection of the unknown objects, successively a location of the scatterers and finally a quantitative reconstruction of the scenario under test. Thanks to its properties, the approach allows an effective use of the information achievable from inverse scattering data. Morover, the adopted kind of expansion is able to deal with all possible multiresolution combinations in an easy and computationally inexpensive way. Selected numerical examples concerning dielectric as well as dissipative objects in noisy enviroments or starting from experimantally-acquired data are reported in order to confirm the usefulness of the introduced tool and of the effectiveness of the proposed procedure

Detection of Buried Inhomogeneous Elliptic Cylinders by a Memetic Algorithm

The application of a global optimization procedure to the detection of buried inhomogeneities is studied in the present paper. The object inhomogeneities are schematized as multilayer infinite dielectric cylinders with elliptic cross sections. An efficient recursive analytical procedure is used for the forward scattering computation. A functional is constructed in which the field is expressed in series solution of Mathieu functions. Starting by the input scattered data, the iterative minimization of the functional is performed by a new optimization method called memetic algorithm. (c) 2003 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works

A Reconstruction Procedure for Microwave Nondestructive Evaluation based on a Numerically Computed Green's Function

This paper describes a new microwave diagnostic tool for nondestructive evaluation. The approach, developed in the spatial domain, is based on the numerical computation of the inhomogeneous Green’s function in order to fully exploit all the available a-priori information of the domain under test. The heavy reduction of the computational complexity of the proposed procedure (with respect to standard procedures based on the free-space Green’s function) is also achieved by means of a customized hybrid-coded genetic algorithm. In order to assess the effectiveness of the method, the results of several simulations are presented and discussed

A Numerical Technique for Determining the Internal Field in Biological Bodies Exposed to Electromagnetic Fields

In this paper, the field prediction inside biological bodies exposed to electromagnetic incident waves is addressed by considering inverse scattering techniques. In particular, the aim is to evaluate the possibility of limiting the test area in order to strongly reduce the computational time, ensuring, at the same time, a quite accurate solution. The approach is based on separating the scattering contributions of the region under test and the other part of the biological body. The starting point is represented by the inverse-scattering equations, which are recast as a functional to be minimized. A Green's function approach is then developed in order to include an approximate knowledge (a model) of the biological body. The possible application of the approach for diagnostic purposes is also discussed

Improved Microwave Imaging Procedure for Non-Destructive Evaluations of Two-Dimensional Structures

An improved microwave procedure for detecting defects in dielectric structures is proposed. The procedure is based on the integral equations of the inverse scattering problem. A hybrid Genetic Algorithm is applied in order to minimize the obtained nonlinear functional. Since in nondestructive evaluations the unperturbed object is completely known, it is possible off-line to numerically compute the Green's function for the configuration without defects. Consequently, a very dignificant computation saving is obtained, since the 'chromosome' of the Genetic Algorithm codes only the parameters describing the unknown defect

Synthesis of sum and difference patterns for monopulse antennas by an hybrid real/integer-coded differential evolution method

The synthesis of sum and difference patterns of monopulse antennas is considered in this paper. The synthesis problem is recast as an optimization problem by defining a suitable cost function based on the constraints on the side lobe levels. A subarray configuration is considered and the excitations of the difference pattern are approximately determined. The optimization problem is efficently solved by a differential evolution algorithm, wich is able to contemporarly handle real and integer unknowns. Numerical results are reported considering classic array configurations previusly assumed in the literature

Improved microwave imaging procedure for non-destructive evaluations of two-dimensional structures

Improved microwave imaging procedure for nondestructive evaluations of two dimensional structures Author(s): Caorsi, S (Caorsi, S); Massa, A (Massa, A); Pastorino, M (Pastorino, M); Donelli, M (Donelli, M) Source: IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION Volume: 52 Issue: 6 Pages: 1386-1397 DOI: 10.1109/TAP.2004.830254 Published: JUN 2004 Times Cited: 31 (from Web of Science) Cited References: 23 [ view related records ] Citation Map Abstract: An improved microwave procedure for detecting defects in dielectric structures is proposed. The procedure is based on the integral equations of the inverse scattering problem. A hybrid genetic algorithm (GA) is applied in order to minimize the obtained nonlinear functional. Since in nondestructive evaluations the unperturbed object is completely known, it is possible off-line to numerically compute the. Green's function for the configuration without defects. Consequently, a very significant computation saving is obtained, since the "chromosome" of the GA codes only the parameters describing the unknown defect. Accession Number: WOS:000221857300001 Document Type: Article Language: English Author Keywords: genetic algorithms (GAs); Green's function; microwave imaging; nondestructive evaluation (NDE) KeyWords Plus: GENETIC ALGORITHM; ELECTROMAGNETICS; RECONSTRUCTION Reprint Address: Caorsi, S (reprint author), Univ Pavia, Dept Elect, Via Palestro 3, I-27100 Pavia, Italy Addresses: 1. Univ Pavia, Dept Elect, I-27100 Pavia, Italy E-mail Address: [email protected] Publisher: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 445 HOES LANE, PISCATAWAY, NJ 08855 USA Web of Science Category: Engineering, Electrical & Electronic; Telecommunications Subject Category: Engineering; Telecommunications IDS Number: 826VJ ISSN: 0018-926

A Crack Identification Microwave Procedure based on a Genetic Algorithm for Non-Destructive Testing

This paper is aimed at exploring the possibility of using a microwave approach based on a genetic algorithm to detect a defect inside a known host object. Starting from the knowledge of the scattered field, the problem solution is recast as a two step procedure. After defining a cost function depending on the geometry of the defect on the crack detection and reconstruction is investigated. Moreover, the numerical effectiveness of the iterative approach is examinated. (c) 2001 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works

A Finite Element Procedure Based on a Boundary Value Approach for the Evaluation of the Electromagnetic Exposure in Biological Phantoms

In this paper, a finite element method, based on a boundary value approach, for the evaluation of the electric field distribution in exposed biological phantoms is presented. Starting from the measurement of the electric field around the phantom, the field prediction is obtained by solving a boundary value problem. This allows to avoid the description of the electromagnetic source and the estimation of the electric field distribution also when the illuminating source is unknown or when its numerical model is not available. In order to show the effectiveness of the proposed approach, some numerical results, concerning a two dimensional geometry, are provided. Firstly, the accuracy and validity of the electromagnetic prediction are assessed by comparing numerical with reference solutions (analytically computed). Then, in order to demonstrate the efficiency, the robustness and capability of this technique, different measurement strategies, noisy environments and errors in the data acquisition are taken into account. (c) 2002 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works

Analysis of the stability and Robustness of the Iterative Multi-Scaling Approach for Microwave Imaging Applications

In a reconstruction procedure based on the iterative solution of inverse scattering integral equations, the quality of the final image depends on both the numerical and experimental noise. Numerical noise is related to the accuracy of the numerical representation of the microwave imaging apparatus and system geometry. Experimental noise refers to the non-ideal electromagnetic conditions in which the data acquisition is performed. This paper provides a systematic evaluation of the impact of the most significant sources of numerical and experimental noise on the reconstruction quality when the Iterative Multi-Scaling Approach (IMSA) is used. The assessment of the robustness and stability of the IMSA is carried out by considering synthetic as well as real data. The achieved results provide detailed indications on the range of applicability of the IMSA for qualitative and/or quantitative imaging purposes