ELEDIA Student Project Activities and Theses Reports: No conditions. Results ordered -Date Deposited. 2017-11-22T18:31:32ZEPrintshttp://eledia.science.unitn.it/images/eledialogo.pnghttp://eledia.science.unitn.it/publications/7032012017-11-10T15:19:44Z2017-11-10T15:19:45Zhttp://eledia.science.unitn.it/publications/id/eprint/756This item is in the repository with the URL: http://eledia.science.unitn.it/publications/id/eprint/7562017-11-10T15:19:44ZEfficient Tiling of Large Planar Sub‐Arrayed Phased Arrays Through Schemata‐Driven Evolutionary OptimizationIn this work, the synthesis of large clustered arrays - computationally unaffordable through standard stochastic global optimization techniques - is addressed through an innovative schemata-driven approach. The proposed design methodology is based on the analytic definition of a set of reference tiling arrangements and a customized genetic algorithm (GA)-based strategy which is able to effectively and efficiently explore the solution space of the complete tiling configurations. Some representative numerical experiments are presented in order to verify the effectiveness of the developed synthesis technique for the tiling of large planar phased sub-arrays providing optimal side-lobe level (SLL) radiation performance.N. AnselmiP. RoccaM. SalucciA. Massa2017-11-03T14:36:46Z2017-11-03T14:36:46Zhttp://eledia.science.unitn.it/publications/id/eprint/755This item is in the repository with the URL: http://eledia.science.unitn.it/publications/id/eprint/7552017-11-03T14:36:46ZAn Innovative GA‐Based Synthesis Method for the Design of Small‐Sized Tiled Planar Sub‐Arrayed Phased ArraysIn this work, an innovative methodology for the design of planar sub-arrayed phased arrays composed by irregular arrangements of vertical and horizontal domino-shaped tiles is presented. More precisely, the proposed design method is aimed at optimally synthesizing low and medium size arrays through a suitable customization of mathematical tiling theorems and algorithms. Thanks to the exploitation of a customized genetic algorithm (GA)-based optimization strategy, the retrieval of the global optimal solution for the problem of finding the complete tiling affording the minimum side-lobe level (SLL) is effectively yielded through the proposed approach. A set of numerical benchmarks is presented in order to assess the proposed sub-arraying technique for small-sized problems.N. AnselmiP. RoccaM. SalucciA. Massa2017-10-27T15:04:23Z2017-10-27T15:04:23Zhttp://eledia.science.unitn.it/publications/id/eprint/754This item is in the repository with the URL: http://eledia.science.unitn.it/publications/id/eprint/7542017-10-27T15:04:23ZDesign of Planar Sub‐Arrayed Phased Arrays Through Irregular Domino‐Shaped TilesIn this work, the design of planar sub-arrayed phased arrays through irregular domino-shaped tiles is presented. An innovative enumerative approach is exploited to synthesize the optimal clustering in order to obtain the maximum aperture coverage and radiation performance. Moreover, a design procedure based on optimal tiling theorems drawn from mathematical theory and exploiting a customized genetic algorithm (GA) optimizer to effectively minimize a suitably defined cost function is proposed. Some preliminary numerical results are presented in order to assess the potentialities of the proposed synthesis methods for small-sized arrays.N. AnselmiP. RoccaM. SalucciA. Massa2017-10-16T07:31:11Z2017-10-16T07:31:11Zhttp://eledia.science.unitn.it/publications/id/eprint/753This item is in the repository with the URL: http://eledia.science.unitn.it/publications/id/eprint/7532017-10-16T07:31:11ZSynthesis of Wideband WAIMs within the System‐by‐Design FrameworkIn this work, the design of wideband wide-angle impedance matching (WAIM) structures is proposed for waveguide-fed planar phased arrays. An innovative System-by-Design (SbD) approach is exploited to determine the geometrical descriptors of the WAIM, which is composed by a metasurface of regularly-arranged microstrip printed unit cells. The proposed solution technique is based on the combination of elementary functional blocks aimed at (i) exploring the search space, (ii) analyzing the resulting metasurface structure to deduce the equivalent permittivity/permeability tensors, (iii) computing the phased array response, and (iv) linking the obtained result with the problem constraints and objectives to determine the associated cost function. Some numerical results are shown in order to assess the effectiveness of the SbD-based design strategy.G. OliveriM. SalucciN. AnselmiA. Massa2017-10-09T07:57:30Z2017-10-09T07:57:30Zhttp://eledia.science.unitn.it/publications/id/eprint/752This item is in the repository with the URL: http://eledia.science.unitn.it/publications/id/eprint/7522017-10-09T07:57:30ZParticle Swarm Optimization of Innovative Wide Angle Impedance Matching MetasurfacesThe design of innovative wide-angle impedance matching (WAIM) structures is proposed to mitigate reflection issues arising when scanning waveguide-fed planar phased arrays. The WAIM is based on a metasurface which is composed by several unit cells arranged according to a triangular lattice. A System-by-Design (SbD) approach is exploited to synthesize - by means of a customized particle swarm optimization (PSO)-based algorithm - the geometrical descriptors of such a metasurface in order to reduce the reflections when steering the main beam of the array. Numerical results are shown in order to verify the effectiveness as well as the potentialities of the developed design strategy.G. OliveriM. SalucciN. AnselmiA. Massa2017-10-02T08:11:43Z2017-10-02T08:11:43Zhttp://eledia.science.unitn.it/publications/id/eprint/749This item is in the repository with the URL: http://eledia.science.unitn.it/publications/id/eprint/7492017-10-02T08:11:43ZInnovative Design of Metamaterial Printed WAIMs through a System-by-Design ApproachAn innovative approach is proposed for the synthesis of WAIM structures able to compensate the inter‐element coupling effects limiting the maximum scanning angles of active electronically‐scanned arrays (AESAs). The WAIM is composed by a metasurface represented by a regular grid of microstrip printed unit cells organized according to an hexagonal lattice. Accordingly, the geometrical descriptors of the unit cells are synthesized through a System‐by‐Design (SbD) approach aimed at minimizing the antenna input reflections caused by impedance mismatching when the array is steered. Some numerical results are shown in order to assess the effectiveness of the proposed design methodology.G. OliveriM. SalucciN. AnselmiA. Massa2017-09-22T15:04:34Z2017-09-22T15:04:34Zhttp://eledia.science.unitn.it/publications/id/eprint/748This item is in the repository with the URL: http://eledia.science.unitn.it/publications/id/eprint/7482017-09-22T15:04:34ZA System‐by‐Design Approach for the Synthesis of WAIMs for Planar ArraysIn this work, wide-angle impedance matching (WAIM) layers based on metasurfaces are designed to enhance the radiation efficiency of planar phased arrays. Toward this end, a System-by-Design (SbD) approach is adopted where the layer geometrical features are the solution descriptors, while the minimization of the array power reflection is the synthesis objective. Selected numerical examples are shown to illustrate the potentialities of the proposed SbD-based design strategy.G. OliveriM. SalucciN. AnselmiA. Massa2017-09-15T11:56:56Z2017-09-15T11:56:56Zhttp://eledia.science.unitn.it/publications/id/eprint/747This item is in the repository with the URL: http://eledia.science.unitn.it/publications/id/eprint/7472017-09-15T11:56:56ZInnovative Synthesis of WAIM Layers for Waveguide‐Fed Planar Phased ArraysThis work deals with the design of wide-angle impedance matching (WAIM) layers aimed at mitigating reflection issues arising in waveguide-fed planar phased arrays. The synthesis problem is formulated within the System-by-Design (SbD) framework, by minimizing the antenna input reflections caused by impedance mismatching when the array is steered through the optimization of the geometrical descriptors of the WAIM unit cells. Some numerical results are shown in order to assess the effectiveness of the proposed synthesis strategy.G. OliveriM. SalucciN. AnselmiA. Massa2017-09-08T14:26:08Z2017-09-08T14:26:08Zhttp://eledia.science.unitn.it/publications/id/eprint/746This item is in the repository with the URL: http://eledia.science.unitn.it/publications/id/eprint/7462017-09-08T14:26:08ZSystem‐by‐Design Synthesis of Wide Angle Impedance Matching LayersIn this work, the synthesis of metasurface-based wide-angle impedance matching (WAIM) layers is proposed. The designed structures allow to mitigate reflection issues in waveguide-fed planar phased arrays. To achieve such a goal, the synthesis problem is formulated in the System-by-Design (SbD) framework, and the degrees of freedom are represented by the geometrical descriptors of the metasurface unit cells. The final layout is then obtained by minimizing the antenna input reflections caused by impedance mismatching when the array is steered. A preliminary numerical validation is provided in order to assess the effectiveness and flexibility of the proposed SbD-based design approach.G. OliveriM. SalucciN. AnselmiA. Massa2017-08-23T14:52:46Z2017-08-23T14:52:46Zhttp://eledia.science.unitn.it/publications/id/eprint/745This item is in the repository with the URL: http://eledia.science.unitn.it/publications/id/eprint/7452017-08-23T14:52:46ZDictionary‐Based Bayesian Compressive Sensing for Imaging Arbitrary ScatterersThis work deals with an innovative free-space inverse scattering technique. The developed methodology is based on the exploitation of a Bayesian Compressive Sensing (BCS) solver and a set (or dictionary) of expansion bases. Several BCS-regularized reconstructions are performed using the different bases in the dictionary, and the sparsest solution is selected as the most reliable one. Thanks to such an approach, (i) no a-priori information about the unknown scatterers is required, and (ii) it is possible to extend the range of applicability of standard BCS-based inversion to objects having arbitrary size and shape. In order to verify the effectiveness of the proposed technique, as well as to test its robustness to noise, some illustrative numerical results are shown in the following. N. AnselmiG. OliveriM. HannanM. SalucciA. Massa2017-08-14T12:40:26Z2017-08-14T12:40:26Zhttp://eledia.science.unitn.it/publications/id/eprint/744This item is in the repository with the URL: http://eledia.science.unitn.it/publications/id/eprint/7442017-08-14T12:40:26ZAn Innovative BCS‐Based Microwave Imaging Technique for Imaging Unknown Objects With Arbitrary Size and ShapeThis work presents a numerical validation of an innovative two-dimensional (2D) microwave inverse scattering technique exploiting Bayesian Compressive Sensing (BCS) and a dictionary of wavelet-based expansion bases. The goal of the dictionary-based BCS is to provide faithful guesses of the dielectric distribution inside the imaged scenario even if the unknown objects inside it are not sparse in the standard pixel basis. The developed strategy is based on a two-level hierarchical application of the BCS algorithm. In the first step, several sparsity-regularized inversions are performed using the dictionary of candidate bases. In the second step, the retrieved vectors are compared and the sparsest reconstruction is selected. Some numerical results are shown, in order to verify the effectiveness of the developed microwave imaging technique. Moreover, some illustrative results are shown to compare its performance with respect to competitive state-of-the-art alternatives.N. AnselmiG. OliveriM. HannanM. SalucciA. Massa2017-08-04T15:19:45Z2017-08-04T15:19:45Zhttp://eledia.science.unitn.it/publications/id/eprint/743This item is in the repository with the URL: http://eledia.science.unitn.it/publications/id/eprint/7432017-08-04T15:19:45ZExtending the Applicability Range of Compressive Sensing‐Based Microwave Imaging to Arbitrary Scatterers This work deals with an innovative two-dimensional (2D) free-space microwave imaging technique. The developed inverse scattering (IS) technique is aimed at enabling Compressive Sensing (CS) to deal with the retrieval of unknown scatterers which are not necessarily sparse in the standard sense, i.e., in the pixel domain. Accordingly, the proposed technique exploits a user-defined dictionary of expansion bases that are used to retrieve several guesses of the electromagnetic properties of the investigation domain. Then, following the BCS paradigm, the sparsest solution is recognized as the optimal one. Some numerical results are presented, in order to verify the effectiveness of the proposed IS technique for imaging scatterers with arbitrary size and shape.N. AnselmiG. OliveriM. HannanM. SalucciA. Massa2017-07-28T15:46:06Z2017-07-28T15:46:06Zhttp://eledia.science.unitn.it/publications/id/eprint/742This item is in the repository with the URL: http://eledia.science.unitn.it/publications/id/eprint/7422017-07-28T15:46:06ZInnovative Alphabet‐Based Bayesian Compressive Sensing Technique for Imaging Targets with Arbitrary ShapeIn this work an innovative two-dimensional (2D) microwave imaging technique exploiting Bayesian Compressive Sensing (BCS) and a wavelet-based alphabet for representing the problem unknowns is dealt with. The proposed approach is based on the generalization of the sparsity concept, extending the range of applicability of BCS-based inverse scattering (IS) techniques to objects with arbitrary shape and dimensions. A set of BCS reconstructions is performed considering different expansion bases in the alphabet, without the need for a-priori knowledge about the unknown scatterers. Then, the best reconstruction is recognized as that minimizing the number of non-null retrieved coefficients (i.e., the sparsest one). In order to verify the effectiveness of the proposed imaging technique, a set of representative numerical benchmarks is presented. Some comparisons with state-of-the-art IS techniques are presented, as well.N. AnselmiG. OliveriM. HannanM. SalucciA. Massa2017-07-21T12:47:48Z2017-07-21T13:45:32Zhttp://eledia.science.unitn.it/publications/id/eprint/741This item is in the repository with the URL: http://eledia.science.unitn.it/publications/id/eprint/7412017-07-21T12:47:48ZFree‐Space Microwave Imaging through Alphabet‐Based Bayesian Compressive SensingA key requirement to be satisfied when exploiting Compressive Sensing (CS) methods in inverse scattering (IS) problems is that the unknowns (e.g., the contrast function or the equivalent sources) are sparse with respect to the considered expansion basis. State-of-the-art CS-based microwave imaging techniques typically consider single-resolution pixel-based representations, limiting their domain of applicability to the retrieval of few and isolated pixels within the investigated domain. Within this framework, this work is aimed at extending the range of applicability of CS-based approaches to the retrieval of unknown scatterers having arbitrary shape and dimensions. Since in real applications no a-priori information about the investigation domain is available, the idea is to retrieve a set of "candidate" solutions by executing several CS inversions using different expansion bases (e.g., pixel, Haar wavelets, Meyer wavelets, ...). Following the CS paradigm, the "best" solution can then be identified as the sparsest one, i.e., the solution with the lowest number of non-zero retrieved coefficients. A preliminary numerical validation of the proposed alphabet-based CS microwave imaging technique is given. Some numerical comparisons with competitive state-of-the-art inverse scattering techniques is shown, as well.N. AnselmiG. OliveriM. HannanM. SalucciA. Massa2017-07-14T11:17:21Z2017-07-14T11:17:21Zhttp://eledia.science.unitn.it/publications/id/eprint/740This item is in the repository with the URL: http://eledia.science.unitn.it/publications/id/eprint/7402017-07-14T11:17:21ZAn Evolutionary Optimization Method for Solving the Multi-Frequency GPR Subsurface ProblemIn this work, the two-dimensional subsurface imaging problem is solved by processing wide-band ground penetrating radar (GPR) data. Towards this end, an innovative microwave inverse scattering technique is presented. The developed methodology is based on a particle swarm optimization (PSO) solver to minimize the arising multi-frequency (MF) cost function measuring the mismatch between measured and retrieved data. Moreover, an iterative multi-resolution strategy is exploited in order to progressively and adaptively refine the resolution of the retrieved images only within the regions of interest in which the presence of a buried object has been detected. Some numerical results are shown, in order to assess the effectiveness of the developed MF-IMSA-PSO strategy in reconstructing dielectric objects buried at different depths. Some experiments are also shown to verify the robustness of the proposed method when the background permittivity is not constant but smoothly varying with the distance from the interface.M. SalucciL. PoliN. AnselmiA. Massa2017-07-11T16:00:24Z2017-07-12T14:06:59Zhttp://eledia.science.unitn.it/publications/id/eprint/739This item is in the repository with the URL: http://eledia.science.unitn.it/publications/id/eprint/7392017-07-11T16:00:24ZMulti‐Resolution Processing of Multi‐Frequency GPR Data for Robust Buried Object ImagingThis work presents an innovative GPR microwave imaging technique aimed at
retrieving the electromagnetic properties of inaccessible domains buried below a
planar interface. The arising two‐dimensional (2‐D) inverse scattering problem is
solved taking into account for the wide‐band nature of GPR data by exploiting a
multi frequency (MF) solution approach. Moreover, a customized multiresolution
particle swarm optimizer (IMSA‐PSO) is exploited in order to minimize
the MF cost function by adaptively refining the image resolution only in the
identified regions of interest (RoIs). A set of numerical experiments is shown in
order to verify the effectiveness of the developed MF‐IMSA‐PSO technique when
the background permittivity is not exactly known. A comparative assessment
with respect to a deterministic local search‐based microwave imaging technique
is given, as well, to highlight the superior performances yielded by the
exploitation of the PSO solver.M. SalucciL. PoliN. AnselmiAndrea Massa2017-06-29T07:27:29Z2017-06-29T07:27:29Zhttp://eledia.science.unitn.it/publications/id/eprint/737This item is in the repository with the URL: http://eledia.science.unitn.it/publications/id/eprint/7372017-06-29T07:27:29ZRobust Multi-Frequency GPR Microwave Imaging through Multi-Scaling Particle Swarm OptimizationIn this work, an innovative GPR microwave imaging technique is proposed for solving the subsurface inverse scattering problem in a multi-frequency (MF) framework. The proposed technique exploits a stochastic optimizer based on particle swarm optimization (PSO) in order to effectively deal with the minimization of the MF cost function without being trapped into false solutions. Moreover, the iterative multi-scaling approach (IMSA) is exploited in order to achieve higher resolutions within the identified regions of interest. Some numerical results are shown, carefully selected from an extensive validation of the method, in order to assess its performance when dealing with the retrieval of buried objects under several noise levels. More precisely, a variation of the number of measurement points placed above the interface to collect the scattered radargram is considered, in order to investigate the robustness of the developed method, as well as to compare it to a deterministic implementation within the same solution framework.M. SalucciL. PoliN. AnselmiA. Massa2017-06-22T07:20:17Z2017-06-22T07:20:17Zhttp://eledia.science.unitn.it/publications/id/eprint/736This item is in the repository with the URL: http://eledia.science.unitn.it/publications/id/eprint/7362017-06-22T07:20:17ZAn Innovative Multi-Frequency PSO-Based Method for the Microwave Imaging of
Buried Objects having Different Conductivities In this work, an innovative particle swarm optimization (PSO)-based microwave imaging approach is presented to solve the subsurface inverse scattering problem. The proposed MF-IMSA-PSO method integrates a customized PSO solver within a multi-scaling technique (i.e., the IMSA) in order to limit the ratio between problem unknowns and non-redundant data, mitigating the negative effects of both non-linearity and ill-posedness through the exploitation of progressively acquired information about the solution. Moreover, the inversion is performed by considering a multi-frequency (MF) solution strategy, by jointly processing several frequency components extracted from the spectrum of the measured data through ground penetrating radar (GPR). Some numerical results are shown in order to verify the effectiveness of the developed GPR microwave imaging technique when dealing with objects having a conductivity different from that of the hosting (lossy) soil.M. SalucciL. PoliN. AnselmiA. Massa2017-06-15T07:14:20Z2017-06-15T07:14:20Zhttp://eledia.science.unitn.it/publications/id/eprint/735This item is in the repository with the URL: http://eledia.science.unitn.it/publications/id/eprint/7352017-06-15T07:14:20ZMicrowave Imaging of Buried Objects having Different Permittivities through an Innovative Multi-Frequency Stochastic MethodThis work deals with the retrieval of the electromagnetic characteristics of inaccessible subsurface domains by processing ground penetrating radar (GPR) data. Assuming a multi-frequency (MF) formulation of the buried inverse scattering problem, the solution is obtained by means of a multi-resolution particle swarm optimization (PSO) algorithm. The developed MF-IMSA-PSO method is able to proficiently exploit the intrinsic frequency diversity of wideband GPR measurements in order to mitigate the ill-posedness and non-linearity issues of the subsurface inverse scattering problem. Moreover, thanks to the integration of the PSO within the iterative multi-scaling approach (IMSA) an increased resolution of the retrieved images is obtained within the identified regions of interest, where the buried objects are supposed to lie. Some numerical experiments are shown in order to assess the effectiveness, the robustness to noise, as well as the current limitations, of the developed method in retrieving buried scatterers having different levels of electric permittivity (i.e., different levels of contrast with respect to the surrounding background medium). Moreover, a direct comparison with respect to the MF-IMSA-CG, a state-of-the-art approach based on a conjugate gradient (CG) local search algorithm, is given.M. SalucciL. PoliN. AnselmiA. Massa2017-06-08T13:16:17Z2017-06-08T13:16:17Zhttp://eledia.science.unitn.it/publications/id/eprint/734This item is in the repository with the URL: http://eledia.science.unitn.it/publications/id/eprint/7342017-06-08T13:16:17ZRobust Multi-Frequency Subsurface Imaging through Evolutionary OptimizationIn this work, an innovative stochastic method for subsurface microwave imaging is presented. The proposed approach solves the subsurface inverse scattering problem by jointly processing multiple frequency components of the measured wide-band ground penetrating radar (GPR) data. Moreover, an iterative multi-zooming approach is adopted, in order to reduce the ratio between problem unknowns and informative data, as well as to adaptively enforce increased resolutions in correspondence with the identified regions of interest. The minimization of the multi-frequency (MF) cost function is performed at each multi-resolution step by means of a customized particle swarm optimization (PSO) algorithm, thanks to its capability of escaping from local minima, corresponding to false solutions of the inverse scattering problem. Some numerical results are shown, in order to assess the performance of the developed MF-IMSA-PSO method in retrieving buried targets having different shape and composition, as well as to compare it to a deterministic implementation within the same framework (i.e., the MF-IMSA-CG).M. SalucciL. PoliN. AnselmiA. Massa