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Rocco Pierri

Publications and source records attributed to Rocco Pierri.

6 recordsLinked to original sources
PubMed2004

Imaging of voids by means of a physical-optics-based shape-reconstruction algorithm.

We analyze the performance of a shape-reconstruction algorithm for the retrieval of voids starting from the electromagnetic scattered field. Such an algorithm exploits the physical optics (PO) approximation to obtain a linear unknown-data relationship and performs inversions by means of the singular-value-decomposition approach. In the case of voids, in addition to a geometrical optics reflection, the presence of the lateral wave phenomenon must be considered. We analyze the effect of the presence of lateral waves on the reconstructions. For the sake of shape reconstruction, we can regard the PO algorithm as one of assuming the electric and magnetic field on the illuminated side as constant in amplitude and linear in phase, as far as the dependence on the frequency is concerned. Therefore we analyze how much the lateral wave phenomenon impairs such an assumption, and we show inversions for both one single and two circular voids, for different values of the background permittivity.

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PubMed2004

Multistatic-multiview resolution from Born fields for strips in Fresnel zone.

We address the inverse scattering problem of estimating the resolution limits achievable in the reconstruction of a dielectric strip object within a two-dimensional and scalar geometry. The scattered field is observed over a bounded rectilinear domain located in the Fresnel zone, and a single-frequency multistatic-multiview configuration is considered. The analysis is performed by casting the problem as the inversion of the linearized scattering operator arising from the Born approximation and by means of its singular-value decomposition. Finally, the role of the geometrical parameters of the measurement configuration is highlighted.

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PubMed2003

Shape identification by physical optics: the two-dimensional TE case.

A method is provided for reconstruction of the shape of perfectly conducting objects in a homogeneous space starting from knowledge of the scattered far field under the incidence of TE-polarized plane waves. The Kirchhoff model of scattering permits linearization of the inverse problem, which is further simplified by adopting an asymptotic approximation. Thus the problem is tackled with an approach based on singular-value decomposition already developed for the TM case.

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PubMed2002

Imaging perfectly conducting objects as support of induced currents: Kirchhoff approximation and frequency diversity.

The problem of determining the shape of perfectly conducting objects from knowledge of the scattered electric field is considered. The formulation of the problem accommodates the nature of the distribution of the induced surface current density. Thus, as the unknown representing the object's contour, a single layer distribution is chosen so that the contour of the scatterer is described by its support. The nonlinear unknown-data mapping is then linearized by means of the Kirchhoff approximation, and the problem is recast as the inversion of a linear operator acting on a distribution space. An extension of the singular value decomposition approach to solve the linearized problem is provided and numerical results are presented.

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PubMed2002

Convergence properties of a quadratic approach to the inverse-scattering problem.

The local-minima question that arises in the framework of a quadratic approach to inverse-scattering problems is investigated. In particular, a sufficient condition for the absence of local minima is given, and some guidelines to ensure the reliability of the algorithm are outlined for the case of data not belonging to the range of the relevant quadratic operator. This is relevant also when an iterated solution procedure based on a quadratic approximation of the electromagnetic scattering at each step is considered.

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