Alessandro Fedeli

A Multifrequency Inexact-Newton Method in

An electromagnetic inverse scattering approach for imaging of shallow subsurface objects is reported. It extends to multifrequency processing, an efficient method previously developed for single frequency imaging. The considered approach is an iterative procedure based on an inexact-Newton method developed in

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Banach Spaces for Buried Objects Detection

Banach spaces, which exhibits effective regularization capabilities and reduced over-smoothing effects. The approach is validated using numerical simulations in which cylindrical scatterers are reconstructed in a homogeneous lossy medium. Results are compared with those obtained using standard single frequency operating conditions.

Buried object detection by means of a Lp Banach-space inversion procedure

Electromagnetic imaging of buried targets is an important task that arises in several applicative fields, such as civil engineering and archeology. In the present paper, an algorithm based on a regularizing approach in Lp Banach spaces is applied to the integral equations of the inverse scattering problem. The effectiveness of the approach is verified by means of preliminary numerical simulations in which buried target are illuminated by a set of incident waves in a noisy environment.

A Microwave Tomographic System for Wood Characterization in the Forest Products Industry

Abstract Nondestructive testing and evaluation techniques able to extract information about the internal structure of the samples under test are very important in the wood industry. Microwave imaging systems have been considered for a long time promising apparatuses for this task. In this framework, approaches exploiting the full scattering phenomena for creating images of the distributions of the dielectric properties of the targets have been developed in the last few years. In this paper, a prototype of microwave tomographic system is presented and several experimental validation confirming its suitability for the use in the wood and forest product industry are reported.

Microwave imaging of elliptically shaped dielectric cylinders by means of an Lp Banach-space inversion algorithm

Microwave imaging apparatuses have become very important tools in the framework of imaging systems. However, particular care must be used when developing the data processing algorithm needed to solve the underlying nonlinear and ill-posed inverse problem. Usually, regularization techniques developed in the framework of Hilbert spaces are used. In this paper, a new approach, based on a regularization in the framework of Lp Banach spaces is considered and its performances are evaluated by considering a reference canonical target with elliptical cross section.

Preliminary test of a prototype of microwave axial tomograph for medical applications

An existing prototype of microwave imaging tomograph, previously designed by the present Authors for non destructive testing (NDT) applications, has been adapted in order to deal with biomedical targets. The developed system allows collecting multi-view multi-frequency data. An efficient inversion procedure is used to retrieve the distributions of the dielectric properties from the measured field samples. Some numerical simulations aimed at validating the proposed system and preliminary measurement results obtained by using a breast phantom are presented in this paper.

A numerical study concerning brain stroke detection by microwave imaging systems

In this paper, a numerical study devoted to evaluate the application of a microwave imaging method for brain stroke detection is described. First of all, suitable operating conditions for the imaging system are defined by solving the forward electromagnetic scattering problem with respect to simplified configurations and analyzing the interactions between an illuminating electromagnetic wave at microwave frequencies and the biological tissues inside the head. Then, preliminary inversion results are obtained by applying an imaging procedure based on an iterative Gauss-Newton scheme to a realistic model of the human head. The proposed imaging algorithm is able to deal with the nonlinear and ill-posed problem associated to the integral equations describing the inverse scattering problem. The aim of the inversion procedure is related to the determination of the presence of a hemorrhagic brain stroke by retrieving the distributions of the dielectric parameters of the human tissues inside a slice of the head model.

Brain stroke detection by microwave imaging systems: Preliminary two-dimensional numerical simulations

In this paper, a microwave imaging method is proposed for brain stroke detection. In particular, the developed imaging procedure is based on an iterative Gauss-Newton scheme and it is aimed at determining the presence of a hemorrhagic brain stroke. Interrogating microwaves are used in a multistatic and multiview arrangement. Preliminary numerical results concerning the reconstruction of a simulated stroke inside a two-dimensional slice of the human head are reported. A numerical model is used to obtain the synthetic data used in the inversion process through the solution of a forward electromagnetic scattering problem, which is performed under transverse magnetic conditions.

Experimental validation of a novel Gauss-Newton inversion method for microwave tomographic imaging

Microwave imaging systems are acquiring an ever growing importance. In order to tackle the nonlinearity and illposedness of the underlying inverse scattering problems, several inversion approaches have been formulated in the scientific community. In this framework, an efficient Gauss-Newton method, based on a regularization in Banach spaces, has been recently developed and numerically tested. In this paper, an experimental validation of the approach using real data is provided.