Evaluation of the Number of Degrees of Freedom of the Field Scattered by a 3D Geometry
The solution to an ill-posed linear inverse problem requires the use of regularization methods to achieve a stable approximation solution. One powerful approach is the truncated singular value decomposition (TSVD), but it requires an appropriate choice of the truncation level. One suitable option is...
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MDPI AG
2023-04-01
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| Series: | Sensors |
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| Online Access: | https://www.mdpi.com/1424-8220/23/8/4056 |
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| author | Ehsan Akbari Sekehravani Giovanni Leone Rocco Pierri |
| author_facet | Ehsan Akbari Sekehravani Giovanni Leone Rocco Pierri |
| author_sort | Ehsan Akbari Sekehravani |
| collection | DOAJ |
| description | The solution to an ill-posed linear inverse problem requires the use of regularization methods to achieve a stable approximation solution. One powerful approach is the truncated singular value decomposition (TSVD), but it requires an appropriate choice of the truncation level. One suitable option is to take into account the number of degrees of freedom (NDF) of the scattered field, which is defined by the step-like behavior of the singular values of the relevant operator. Then, the NDF can be estimated as the number of singular values preceding the knee or the exponential decay. Therefore, an analytical estimation of the NDF is significant for obtaining a stable, regularized solution. This paper addresses the analytical estimation of the NDF of the field scattered by the surface of a cube geometry for a single frequency and the multi-view case in the far-zone. In addition, a method is proposed to find the minimum numbers of plane waves and their directions to achieve the total estimated NDF. The main results are that the NDF is related to the measure of the surface of the cube and can be achieved by only considering a limited number of impinging plane waves. The efficiency of the theoretical discussion is demonstrated through a reconstruction application for microwave tomography of a dielectric object. Numerical examples are provided to confirm the theoretical results. |
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| issn | 1424-8220 |
| language | English |
| last_indexed | 2024-03-11T04:33:21Z |
| publishDate | 2023-04-01 |
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| series | Sensors |
| spelling | doaj.art-be9fe1e59e5540d099259e2a6e6485de2023-11-17T21:18:24ZengMDPI AGSensors1424-82202023-04-01238405610.3390/s23084056Evaluation of the Number of Degrees of Freedom of the Field Scattered by a 3D GeometryEhsan Akbari Sekehravani0Giovanni Leone1Rocco Pierri2Department of Engineering, University of Campania “Luigi Vanvitelli”, I-81031 Aversa, ItalyDepartment of Engineering, University of Campania “Luigi Vanvitelli”, I-81031 Aversa, ItalyDepartment of Engineering, University of Campania “Luigi Vanvitelli”, I-81031 Aversa, ItalyThe solution to an ill-posed linear inverse problem requires the use of regularization methods to achieve a stable approximation solution. One powerful approach is the truncated singular value decomposition (TSVD), but it requires an appropriate choice of the truncation level. One suitable option is to take into account the number of degrees of freedom (NDF) of the scattered field, which is defined by the step-like behavior of the singular values of the relevant operator. Then, the NDF can be estimated as the number of singular values preceding the knee or the exponential decay. Therefore, an analytical estimation of the NDF is significant for obtaining a stable, regularized solution. This paper addresses the analytical estimation of the NDF of the field scattered by the surface of a cube geometry for a single frequency and the multi-view case in the far-zone. In addition, a method is proposed to find the minimum numbers of plane waves and their directions to achieve the total estimated NDF. The main results are that the NDF is related to the measure of the surface of the cube and can be achieved by only considering a limited number of impinging plane waves. The efficiency of the theoretical discussion is demonstrated through a reconstruction application for microwave tomography of a dielectric object. Numerical examples are provided to confirm the theoretical results.https://www.mdpi.com/1424-8220/23/8/4056linear inverse scatteringnumber of degrees of freedom3D geometrymicrowave tomography of dielectric objectTSVD inversion |
| spellingShingle | Ehsan Akbari Sekehravani Giovanni Leone Rocco Pierri Evaluation of the Number of Degrees of Freedom of the Field Scattered by a 3D Geometry Sensors linear inverse scattering number of degrees of freedom 3D geometry microwave tomography of dielectric object TSVD inversion |
| title | Evaluation of the Number of Degrees of Freedom of the Field Scattered by a 3D Geometry |
| title_full | Evaluation of the Number of Degrees of Freedom of the Field Scattered by a 3D Geometry |
| title_fullStr | Evaluation of the Number of Degrees of Freedom of the Field Scattered by a 3D Geometry |
| title_full_unstemmed | Evaluation of the Number of Degrees of Freedom of the Field Scattered by a 3D Geometry |
| title_short | Evaluation of the Number of Degrees of Freedom of the Field Scattered by a 3D Geometry |
| title_sort | evaluation of the number of degrees of freedom of the field scattered by a 3d geometry |
| topic | linear inverse scattering number of degrees of freedom 3D geometry microwave tomography of dielectric object TSVD inversion |
| url | https://www.mdpi.com/1424-8220/23/8/4056 |
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