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

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

Buried Object Detection by an Inexact Newton Method Applied to Nonlinear Inverse Scattering

An approach to reconstruct buried objects is proposed. It is based on the integral equations of the electromagnetic inverse scattering problem, written in terms of the Green's function for half-space geometries. The full nonlinearity of the problem is exploited in order to inspect strong scatterers. After discretization of the continuous model, the resulting equations are solved in a regularization sense by means of a two-step inexact Newton algorithm. The capabilities and limitations of the method are evaluated by means of some numerical simulations

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

A Rain Estimation System Based on Electromagnetic Propagation Models and DVB-S Opportunistic Sensors

Weather conditions have in general huge impact on the global economy, in particular on agriculture, industry, transport, and so forth. In recent years, also the occurrences of rapid and localized heavy rainfall in complex topographic areas became more frequent, possibly due to global warming. These facts cause injuries and deaths, and an accurate and early alert system is required to warn people and operators. In this chapter, we describe a real-time and low-cost system for precipitation detection, aimed at collecting additional data with respect to those obtainable from traditional sensors. Such a system is based on the opportunistic usage of satellite digital video broadcasting (DVB-S) microwave signals and estimates the rain intensity from the detected attenuation. Our system proved to accurately obtain results comparable with rain gauges located in the experimentation area, with much tighter spatial and temporal scales than traditional schemes

Microwave Imaging of Three-Dimensional Targets by Means of an Inexact-Newton-Based Inversion Algorithm

A microwave imaging method previously developed for tomographic inspection of dielectric targets is extended to three-dimensional objects. The approach is based on the full vector equations of the electromagnetic inverse scattering problem. The ill-posedness of the problem is faced by the application of an inexact-Newton method. Preliminary reconstruction results are reported

Electromagnetic biomedical imaging in Banach spaces: A numerical case study

This paper reports the results of the application of a microwave imaging method developed in Banach spaces to a model of human head in presence of a hemorrhagic brain stroke. The approach is based on the integral equations of the inverse scattering problem. A Gauss-Newton scheme is adopted as a solving procedure. Being developed in Banach spaces, the method turns out to be quite efficient in reducing the over-smoothing effects usually associated to Hilbert-space reconstructions. Numerical simulations are reported involving a realistic model of human head

A two-step multifrequency imaging technique for ground penetrating radar

In the present paper, a combined method for ground penetrating radar imaging is presented. The proposed technique has a first step in which the electric field scattered by the buried structure is estimated and a qualitative reconstruction is obtained, and a second quantitative inversion step for reconstructing the dielectric properties of the buried targets. The full-wave multifrequency inexact-Newton inversion approach used in the second step uses the information about the target position extracted by the qualitative procedure and takes the scattered field data estimated by a time-domain filtering method. Numerical simulations are presented to prove the effectiveness of the proposed technique

GPR imaging techniques for non-destructive inspection of concrete structures

open4noVol. 21, EGU2019-8897openRandazzo, Andrea; Fedeli, Alessandro; Pastorino, Matteo; Pajewski, LaraRandazzo, Andrea; Fedeli, Alessandro; Pastorino, Matteo; Pajewski, Lar