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

2021 ◽  
pp. 1-1
Author(s):  
G. Leone ◽  
F. Munno ◽  
R. Pierri
Keyword(s):  
Circular Arc ◽  
Conformal Arrays ◽  
Limited Angle

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.

The Complete Mutual Coupling Analysis and Calibration for Conformal Arrays with Nonideal Ports Fed

2014 ◽  
Vol 35 (6) ◽  
pp. 1490-1495
Author(s):  
Fei Zhao ◽  
Sheng-shui Wang ◽  
Shun-lian Chai ◽  
Hui-ying Qi ◽  
Jian-qing Zhu
Keyword(s):  
Mutual Coupling ◽  
Coupling Analysis ◽  
Conformal Arrays

Limited Angle Tomography Using Volumetric Constraints.

1996 ◽  
Author(s):  
Chaitali Biswas ◽  
Helen R. Na
Keyword(s):  
Limited Angle

scholarly journals Ductile failure analysis of epoxy resin plates containing multiple circular arc cracks by means of the equivalent material concept

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
M. Pourseifi ◽  
A. S. Rahimi
Keyword(s):  
Ductile Failure ◽  
Equivalent Material ◽  
Circular Arc ◽  
Equivalent Material Concept ◽  
Crack Tips ◽  
Fracture Tests ◽  
Polymeric Samples ◽  
Cracked Specimens ◽  
Brittle Fracture Criterion ◽  
Material Concept

AbstractDuctile failure of polymeric samples weakened by circular arc cracks is studied theoretically and experimentally in this research. Various arrangements of cracks with different arc angles are considered in the specimens such that crack tips experienced the mixed mode I/II loading conditions. Fracture tests are conducted on the multi-cracked specimens and their fracture loads are achieved. To provide the results, the equivalent material concept (EMC) is used in conjunction of dislocation method and a brittle fracture criterion such that there is no necessity for performing complex and time-consuming elastic-plastic damage analyses. Theoretical and experimental stress intensity factors are computed and compared with each other by employing the fracture curves which demonstrate the appropriate efficiency of proposed method to predict the tests results.

Guided image filtering based ℓ0 gradient minimization for limited-angle CT image reconstruction

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Tianyi Wang ◽  
Chengxiang Wang ◽  
Kequan Zhao ◽  
Wei Yu ◽  
Min Huang
Keyword(s):  
Iteration Process ◽  
Real Data ◽  
Image Filtering ◽  
Reconstruction Technique ◽  
Ct Reconstruction ◽  
Imaging Device ◽  
Practical Applications ◽  
Guided Image Filtering ◽  
Simultaneous Algebraic Reconstruction Technique ◽  
Limited Angle

Abstract Limited-angle computed tomography (CT) reconstruction problem arises in some practical applications due to restrictions in the scanning environment or CT imaging device. Some artifacts will be presented in image reconstructed by conventional analytical algorithms. Although some regularization strategies have been proposed to suppress the artifacts, such as total variation (TV) minimization, there is still distortion in some edge portions of image. Guided image filtering (GIF) has the advantage of smoothing the image as well as preserving the edge. To further improve the image quality and protect the edge of image, we propose a coupling method, that combines ℓ 0 {\ell_{0}} gradient minimization and GIF. An intermediate result obtained by ℓ 0 {\ell_{0}} gradient minimization is regarded as a guidance image of GIF, then GIF is used to filter the result reconstructed by simultaneous algebraic reconstruction technique (SART) with nonnegative constraint. It should be stressed that the guidance image is dynamically updated as the iteration process, which can transfer the edge to the filtered image. Some simulation and real data experiments are used to evaluate the proposed method. Experimental results show that our method owns some advantages in suppressing the artifacts of limited angle CT and in preserving the edge of image.

Geometry Design and Contact Ratio Analysis for Circular Arc Parallel-Axis Helical Gears

2016 ◽  
Author(s):  
Z. Chen ◽  
B. Lei ◽  
Q. Zhao
Keyword(s):  
Rolling Process ◽  
Helical Gear ◽  
Space Curve ◽  
Impact Factors ◽  
Contact Ratio ◽  
Circular Arc ◽  
Practical Applications ◽  
Geometry Design ◽  
Gear Mechanism ◽  
The Impact

Based on space curve meshing theory, in this paper, we present a novel geometric design of a circular arc helical gear mechanism for parallel transmission with convex-concave circular arc profiles. The parameter equations describing the contact curves for both the driving gear and the driven gear were deduced from the space curve meshing equations, and parameter equations for calculating the convex-concave circular arc profiles were established both for internal meshing and external meshing. Furthermore, a formula for the contact ratio was deduced, and the impact factors influencing the contact ratio are discussed. Using the deduced equations, several numerical examples were considered to validate the contact ratio equation. The circular arc helical gear mechanism investigated in this study showed a high gear transmission performance when considering practical applications, such as a pure rolling process, a high contact ratio, and a large comprehensive strength.

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