Ricerc@Sapienza

This paper addresses the detection of surface slow moving targets by means of an array passive radar based on low-EIRP satellite illuminators of opportunity. Particularly, the use of the receiving array of K elements is considered to provide increased detection capability for targets with limited radar cross section, together with the capability to estimate the target direction-of-arrival. A full processing scheme is proposed to exploit together both the long integration times and the multiple receiving elements.

Microwave thermal ablation (MTA) procedures are based on the absorption of an electromagnetic field irradiated by a minimally invasive antenna. Several studies have been conducted in the past considering different aspects of the technique. However, some points still need to be investigated, as pointed out in the present contribution.

The tomographic algorithms commonly used to process ground penetrating radar (GPR) data assume the scattering phenomenon activated by ideal sources. This can be considered an adequately accurate assumption if the actual GPR antenna presents almost nondirectional features, but should instead properly revisited when a target is illuminated by means of more collimated near-field distributions.

Fabry-Perot cavity antennas with polarization-reconfigurable omnidirectional conical beams are presented. The partially reflecting screen covering the antenna cavity is constituted by omnidirectional homogenized metasurfaces exhibiting rotationally invariant electromagnetic features, and specifically metal patterned screens are considered. The antenna operates on the first higher-order TMi and TEi leaky modes, whose phase and attenuation constants are properly equalized.

In this paper, a new model of the frequency dependence of the double-barrier THz rectifier is presented. The new structure is of interest because it can be realized by CMOS image sensor technology. Its application in a complex field such as that of THz receivers requires the availability of an analytical model, which is reliable and able to highlight the dependence on the parameters of the physical structure. The model is based on the hydrodynamic semiconductor equations, solved in the small signal approximation.

Aim of the present study was to test and validate an ex vivo predictive model for the evaluation of the shrinkage occurring in hepatic tissue during a microwave thermal ablation procedure. Microwave ablation (N=134) was conducted with three different commercial devices on cubes of ex vivo liver (15-40\pm 2 mm side) embedded in agar phantoms. 50-60W was applied for 1-10 min duration. Pre-and post-ablation dimensions of the samples, as well as the extent of carbonization and coagulation were measured.

The shielding effectiveness of a planar multilayered screen is computed in the time domain in the presence of near-field magnetic sources. The proposed numerical method involves the efficient evaluation of classical Sommerfeld integrals and the inverse-Fourier transform through double-exponential formulas. For sufficiently thin screens with highly-conductive properties, an analytical method, based on a modified Cagniard-de Hoop approach, is also presented to validate the results.

It is expected that the pervasive deployment of multi-tier 5G-supported Mobile-Fog-Cloudtechnological computing platforms will constitute an effective means to support the real-time execution of future Internet applications by resource- and energy-limited mobile devices. Increasing interest in this emerging networking-computing technology demands the optimization and performance evaluation of several parts of the underlying infrastructures.

The aim of this work is to investigate the stability to simulated solar radiation of some paintings samples through a new methodological approach adopting non-invasive spectroscopic techniques. In particular, commercial watercolours and iron oxide based pigments were used, these last ones being prepared for the experimental by gum Arabic in order to propose a possible substitute for traditional reintegration materials.

The aim of this work was to recognize different polymer flakes from mixed plastic waste through an innovative hierarchical classification strategy based on hyperspectral imaging, with particular reference to low density polyethylene (LDPE) and high-density polyethylene (HDPE). A plastic waste composition assessment, including also LDPE and HDPE identification, may help to define optimal recycling strategies for product quality control.