scholarly journals Synthesis of Angle Arrays by the NDF of the Radiation Integral

2020 ◽  
Author(s):  
Giovanni Leone ◽  
Fortuna Munno ◽  
Rocco Pierri
Keyword(s):  
Inverse Problem ◽  
Radiation Pattern ◽  
Degrees Of Freedom ◽  
Synthesis Problem ◽  
Radiation Patterns ◽  
Pattern Synthesis ◽  
Source Geometry ◽  
Hemispherical Coverage

<div>This manuscript has been accepted for publication on IEEE Transactions on Antennas and Propagation.</div><div><br>Abstract:<br>The paper adopts an inverse problem approach to investigate the far zone radiation of a collection of 2D linear sources. By the evaluation of the number of independent pieces of information, i.e. the number of degrees of freedom (NDF), and the analysis of the reconstruction of a focusing beam, the role of the geometry can be examined in determining the set of possible radiation patterns. The results are relevant to the radiation pattern synthesis problem, since they allow to define the optimal source geometry for the hemispherical coverage with identical radiation patterns. </div>

scholarly journals Synthesis of Angle Arrays by the NDF of the Radiation Integral

2020 ◽  
Author(s):  
Giovanni Leone ◽  
Fortuna Munno ◽  
Rocco Pierri
Keyword(s):  
Inverse Problem ◽  
Radiation Pattern ◽  
Degrees Of Freedom ◽  
Synthesis Problem ◽  
Radiation Patterns ◽  
Pattern Synthesis ◽  
Source Geometry ◽  
Hemispherical Coverage

<div>This manuscript has been accepted for publication on IEEE Transactions on Antennas and Propagation.</div><div><br>Abstract:<br>The paper adopts an inverse problem approach to investigate the far zone radiation of a collection of 2D linear sources. By the evaluation of the number of independent pieces of information, i.e. the number of degrees of freedom (NDF), and the analysis of the reconstruction of a focusing beam, the role of the geometry can be examined in determining the set of possible radiation patterns. The results are relevant to the radiation pattern synthesis problem, since they allow to define the optimal source geometry for the hemispherical coverage with identical radiation patterns. </div>

scholarly journals Inverse Source on Conformal Conic Geometries

2020 ◽  
Author(s):  
Giovanni Leone ◽  
Fortuna Munno ◽  
Rocco Pierri
Keyword(s):  
Inverse Problem ◽  
Radiation Pattern ◽  
Degrees Of Freedom ◽  
Synthesis Problem ◽  
Source Reconstruction ◽  
Conformal Antennas ◽  
Stable Solutions

This manuscript has been accepted for publication on IEEE Transactions on Antennas and Propagation.<br><br><div>Abstract:</div><div>The paper adopts an inverse problem approach to examine the role of some 2D geometries in the source reconstruction from far zone data. It aims at evaluating the number of independent pieces of information, i.e. the number of degrees of freedom (NDF), of the source and pointing out the set of far zone fields corresponding to stable solutions of the inverse problem. Some of the results are relevant to the synthesis problem of conformal antennas, since a general comparison of different source geometries in providing radiation pattern specifications is proposed.</div>

scholarly journals Inverse Source on Conformal Conic Geometries

2020 ◽  
Author(s):  
Giovanni Leone ◽  
Fortuna Munno ◽  
Rocco Pierri
Keyword(s):  
Inverse Problem ◽  
Radiation Pattern ◽  
Degrees Of Freedom ◽  
Synthesis Problem ◽  
Source Reconstruction ◽  
Conformal Antennas ◽  
Stable Solutions

This manuscript has been accepted for publication on IEEE Transactions on Antennas and Propagation.<br><br><div>Abstract:</div><div>The paper adopts an inverse problem approach to examine the role of some 2D geometries in the source reconstruction from far zone data. It aims at evaluating the number of independent pieces of information, i.e. the number of degrees of freedom (NDF), of the source and pointing out the set of far zone fields corresponding to stable solutions of the inverse problem. Some of the results are relevant to the synthesis problem of conformal antennas, since a general comparison of different source geometries in providing radiation pattern specifications is proposed.</div>

scholarly journals Inverse Source on Conformal Conic Geometries

2020 ◽  
Author(s):  
Giovanni Leone ◽  
Fortuna Munno ◽  
Rocco Pierri
Keyword(s):  
Inverse Problem ◽  
Radiation Pattern ◽  
Degrees Of Freedom ◽  
Synthesis Problem ◽  
Source Reconstruction ◽  
Conformal Antennas ◽  
Stable Solutions

The paper adopts an inverse problem approach to examine the role of some 2D geometries in the source reconstruction from far zone data. It aims at evaluating the number of independent pieces of information, i.e. the number of degrees of freedom (NDF), of the source and pointing out the set of far zone fields corresponding to stable solutions of the inverse problem. Some of the results are relevant to the synthesis problem of conformal antennas, since a general comparison of different source geometries in providing radiation pattern specifications is proposed.

scholarly journals Radiation of a Circular Arc Source in a Limited Angle for Non-uniform Conformal Arrays

2020 ◽  
Author(s):  
Giovanni Leone ◽  
Fortuna Munno ◽  
Rocco Pierri
Keyword(s):  
Inverse Problem ◽  
Degrees Of Freedom ◽  
Angular Width ◽  
Pattern Synthesis ◽  
Circular Arc ◽  
Conformal Antennas ◽  
Radiation Properties ◽  
Near Zone ◽  
Conformal Arrays

Conformal antennas lack of general analysis methods of their radiation properties. For a circumference source, we examine the role of the angular width of the observation domain both in far and near zone in determining the set of radiated fields. By an inverse problem approach, the evaluation of the number of independent pieces of information, i.e. the number of degrees of freedom (NDF), and the analysis of the reconstructions of point-like sources allow to introduce optimal array configurations. The results are relevant to the radiation pattern synthesis problem and to array diagnostics applications.

scholarly journals Radiation of a Circular Arc Source in a Limited Angle for Non-uniform Conformal Arrays

2020 ◽  
Author(s):  
Giovanni Leone ◽  
Fortuna Munno ◽  
Rocco Pierri
Keyword(s):  
Inverse Problem ◽  
Degrees Of Freedom ◽  
Angular Width ◽  
Pattern Synthesis ◽  
Circular Arc ◽  
Conformal Antennas ◽  
Radiation Properties ◽  
Near Zone ◽  
Conformal Arrays

Conformal antennas lack of general analysis methods of their radiation properties. For a circumference source, we examine the role of the angular width of the observation domain both in far and near zone in determining the set of radiated fields. By an inverse problem approach, the evaluation of the number of independent pieces of information, i.e. the number of degrees of freedom (NDF), and the analysis of the reconstructions of point-like sources allow to introduce optimal array configurations. The results are relevant to the radiation pattern synthesis problem and to array diagnostics applications.

scholarly journals Synthesis of High Directivity Beams for Conformal Sources

2021 ◽  
Author(s):  
Giovanni Leone ◽  
Fortuna Munno ◽  
Raffaele Solimene
Keyword(s):  
Degrees Of Freedom ◽  
Singular Values ◽  
Mean Value ◽  
Conformal Antennas ◽  
Optimal Behavior ◽  
Source Current ◽  
Compensation Technique ◽  
The Mean ◽  
Source Geometry

<p>The<b> </b>role of the source geometry in the the radiation of focusing beams by conformal antennas is examined by the comparison of their directivity functions at different maximum directions. An inverse source problem approach is adopted, where solutions stable with respect to data uncertainties are to be found by relying on the analysis of the pertinent operator by the Singular Values Decomposition. This general framework allows to connect the mean value of the mazimum directivity function to the Number of Degrees of Freedom of the conformal source, which depends only on its electrical length. For each source geometry the focusing far field ensuring the maximum directivity for every pointing direction and the corresponding source current are obtained. The comparison with the ones achieved by the usual phase compensation technique of the source current reveals their optimal behavior. The usefulness of the approach as a tool in antenna synthesis is shown by comparing different geometries for those applications where identical beams are required to be rdiated for the coverage of a larga angular domain.</p>

scholarly journals Synthesis of High Directivity Beams for Conformal Sources

2021 ◽  
Author(s):  
Giovanni Leone ◽  
Fortuna Munno ◽  
Raffaele Solimene
Keyword(s):  
Degrees Of Freedom ◽  
Singular Values ◽  
Mean Value ◽  
Conformal Antennas ◽  
Optimal Behavior ◽  
Source Current ◽  
Compensation Technique ◽  
The Mean ◽  
Source Geometry

<p>The<b> </b>role of the source geometry in the the radiation of focusing beams by conformal antennas is examined by the comparison of their directivity functions at different maximum directions. An inverse source problem approach is adopted, where solutions stable with respect to data uncertainties are to be found by relying on the analysis of the pertinent operator by the Singular Values Decomposition. This general framework allows to connect the mean value of the mazimum directivity function to the Number of Degrees of Freedom of the conformal source, which depends only on its electrical length. For each source geometry the focusing far field ensuring the maximum directivity for every pointing direction and the corresponding source current are obtained. The comparison with the ones achieved by the usual phase compensation technique of the source current reveals their optimal behavior. The usefulness of the approach as a tool in antenna synthesis is shown by comparing different geometries for those applications where identical beams are required to be rdiated for the coverage of a larga angular domain.</p>

On the Use of Quantum Thermal Bath in Unimolecular Fragmentation Simulations

2019 ◽  
Author(s):  
Riccardo Spezia ◽  
Hichem Dammak
Keyword(s):  
Degrees Of Freedom ◽  
Molecular Simulations ◽  
Zero Point ◽  
Thermal Bath ◽  
Unimolecular Dissociation ◽  
Point Energy ◽  
Rotational Degrees Of Freedom ◽  
The Difference ◽  
Nuclear Effects

<div> <div> <div> <p>In the present work we have investigated the possibility of using the Quantum Thermal Bath (QTB) method in molecular simulations of unimolecular dissociation processes. Notably, QTB is aimed in introducing quantum nuclear effects with a com- putational time which is basically the same as in newtonian simulations. At this end we have considered the model fragmentation of CH4 for which an analytical function is present in the literature. Moreover, based on the same model a microcanonical algorithm which monitor zero-point energy of products, and eventually modifies tra- jectories, was recently proposed. We have thus compared classical and quantum rate constant with these different models. QTB seems to correctly reproduce some quantum features, in particular the difference between classical and quantum activation energies, making it a promising method to study unimolecular fragmentation of much complex systems with molecular simulations. The role of QTB thermostat on rotational degrees of freedom is also analyzed and discussed. </p> </div> </div> </div>

scholarly journals Dzyaloshinskii–Moriya interaction in noncentrosymmetric superlattices

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Woo Seung Ham ◽  
Abdul-Muizz Pradipto ◽  
Kay Yakushiji ◽  
Kwangsu Kim ◽  
Sonny H. Rhim ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Degrees Of Freedom ◽  
Orbit Coupling ◽  
Inversion Symmetry ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Band Formation ◽  
Research Activities ◽  
Moriya Interaction

AbstractDzyaloshinskii–Moriya interaction (DMI) is considered as one of the most important energies for specific chiral textures such as magnetic skyrmions. The keys of generating DMI are the absence of structural inversion symmetry and exchange energy with spin–orbit coupling. Therefore, a vast majority of research activities about DMI are mainly limited to heavy metal/ferromagnet bilayer systems, only focusing on their interfaces. Here, we report an asymmetric band formation in a superlattices (SL) which arises from inversion symmetry breaking in stacking order of atomic layers, implying the role of bulk-like contribution. Such bulk DMI is more than 300% larger than simple sum of interfacial contribution. Moreover, the asymmetric band is largely affected by strong spin–orbit coupling, showing crucial role of a heavy metal even in the non-interfacial origin of DMI. Our work provides more degrees of freedom to design chiral magnets for spintronics applications.

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