Journal articles on the topic 'Electromagnetic (EM) scattering'
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1
Amna, Ajaz, Jia Dong Xu, and Abdul Mueed. "Development of CEM in Relation to Subsurface Electromagnetic Scattering." Advanced Materials Research 588-589 (November 2012): 2166–70. http://dx.doi.org/10.4028/www.scientific.net/amr.588-589.2166.
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Computational Electromagnetic (CEM) techniques have become an indispensable tool in efficient EM modeling, analysis and design process. EM subsurface scattering is a broad field of research with varying degree of complexity. Due level of the obscurity involved in the subsurface scattering investigation, it is therefore considered imperative to explore this problem area of EM for better insight through CEM-based study and models. In this paper, frequency domain CEM techniques are studied which have been tested to provide solution for subsurface scattering problems in terrestrial environments. The development of CEM methods for comparatively more complex problems of scattering from embedded non-metallic inhomogeneity in lossy, rough and layered media remains the focus of this article. The objective here is to provide an overview of CEM development by selecting few examples from the wide area of subsurface EM scattering.
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Wang, Jie, Hai Lin, Huaihai Guo, Qi Zhang, and Junxiang Ge. "Similarity Study of Electromagnetic and Underwater Acoustic Scattering by Three-Dimensional Targets in Unbounded Space." Journal of Marine Science and Engineering 11, no. 2 (February 17, 2023): 440. http://dx.doi.org/10.3390/jmse11020440.
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The characterization of targets by electromagnetic (EM) scattering and underwater acoustic scattering is an important object of research in these two related fields. However, there are some difficulties in the simulation and measurement of the scattering by large targets. Consequently, a similarity study between acoustic and EM scattering may help to share results between one domain and the other and even provide a general reference method for the simulation of scattering characteristics in both fields. Based on the method of physical optics, the similarity between the EM scattering of conductors and the acoustic scattering of soft/hard targets and the similarity between the EM scattering of dielectrics and the acoustic scattering of elastics are studied. In particular, we derive how to transfer quantities from one domain into another so that similar scattering patterns arise. Then, according to these transfer rules, the EM scattering and acoustic scattering of three typical targets with different types of boundaries were simulated and measured, and the simulated EM scattering and acoustic scattering curves were found to be in perfect agreement, with correlation coefficients above 0.93. The correlation coefficients between the electromagnetic and acoustic scattering patterns were above 0.98, 0.91, and 0.65 for three typical targets. The simulated and measured scattering results verify the proposed similarity theory of EM and acoustic scattering, including the transfer from one domain into the other and the conditions of EM and acoustic scattering, and illustrate that the acoustic scattering characteristic of the target can be simulated using the EM scattering based on the derived conditions and vice versa.
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Ivanchenko, Vladimir, Alexander Bagulya, Samer Bakr, Marilena Bandieramonte, Denis Bernard, Marie-Claude Bordage, Helmut Burkhardt, et al. "Geant4 electromagnetic physics progress." EPJ Web of Conferences 245 (2020): 02009. http://dx.doi.org/10.1051/epjconf/202024502009.
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The Geant4 electromagnetic (EM) physics sub-packages are a component of LHC experiment simulations. During long shutdown 2 for LHC, these packages are under intensive development and we report progress of EM physics in Geant4 versions 10.5 and 10.6, which includes faster computation, more accurate EM models, and extensions to the validation suite. New approaches are developed to simulate radiation damage for silicon vertex detectors and for configuration of multiple scattering per detector region. Improvements in user interfaces developed for low-energy and the Geant4-DNA project are used also for LHC simulation optimisation.
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Wang, Jingjing, Lixin Guo, Yiwen Wei, Shuirong Chai, Ke Li, and Anqi Wang. "Electromagnetic Scattering Analysis of the Sea Surface with Single Breaking Waves." International Journal of Antennas and Propagation 2021 (November 27, 2021): 1–13. http://dx.doi.org/10.1155/2021/1545031.
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A new electromagnetic (EM) scattering model of the sea surface with single breaking waves is proposed based on the high-frequency method in this paper. At first, realistic breaking wave sequences are obtained by solving the fluid equations which are simplified. Then, the rough sea surface is established using the linear filtering method. A new wave model is obtained by combining breaking waves with rough sea surface using a 3D coordinate transformation. Finally, the EM scattering features of the sea surface with breaking waves are studied by using shooting and bouncing rays and the physical theory of diffraction (SBR-PTD). It is found that the structure that is similar to a dihedral corner reflector between the breaking wave and rough sea surface exhibits multiple scattering, which leads to the sea-spike phenomenon that the scattering result of horizontal (HH) polarization is larger than that of vertical (VV) polarization, especially at low-grazing-angle (LGA) incidents with upwind. The sea-spike phenomenon is also closely related to the location of strong scattering.
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Ross, D. C. "EM Programmer's Notebook-some finite-element preprocessing algorithms for electromagnetic scattering." IEEE Antennas and Propagation Magazine 35, no. 3 (June 1993): 68–72. http://dx.doi.org/10.1109/74.250160.
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Rao, Qingwen, Guanjun Xu, and Wangchen Mao. "Detection of the Lunar Surface Soil Permittivity with Megahertz Electromagnetic Wave." Sensors 21, no. 7 (April 2, 2021): 2466. http://dx.doi.org/10.3390/s21072466.
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In this paper, the detection of the lunar surface soil permittivity with megahertz electromagnetic (EM) waves by spaceborne radar is studied based on the EM scattering theory, the Boltzmann–Shukla equations, and the improved scattering matrix method (ISMM). The reflection characteristics of the lunar surface soil subject to megahertz waves are analyzed through the EM scattering theory and expressed by the lunar surface soil permittivity. Then, the lunar ionosphere is assumed to be composed of dusty plasma, and its EM characteristics are described with the Boltzmann–Shukla equations. Finally, the transmission and reflection characteristics of the propagation of EM waves in the lunar ionosphere are numerically calculated with ISMM. Thus, the complex permittivity of lunar surface soil is obtained. In addition, the effects of detection environment situations, such as the lunar illumination intensity, characteristics of the lunar dust and dust charging process in the lunar ionosphere, on the amplitude and phase of EM waves are also investigated in this study. The simulation results show that an EM wave at a high frequency induces a strong effective wave with a stable phase shift and a significantly small interferential wave. Moreover, the lunar illumination is more effective under EM waves in low frequency bands; the characteristics of the lunar dust have a notable influence on the transmission and absorption coefficients of the effective waves. These conclusions help in real applications involving the detection of the lunar surface soil permittivity by spaceborne radar in various lunar environments.
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Sagar, Md Samiul Islam, Hassna Ouassal, Asif I. Omi, Anna Wisniewska, Harikrishnan M. Jalajamony, Renny E. Fernandez, and Praveen K. Sekhar. "Application of Machine Learning in Electromagnetics: Mini-Review." Electronics 10, no. 22 (November 11, 2021): 2752. http://dx.doi.org/10.3390/electronics10222752.
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As an integral part of the electromagnetic system, antennas are becoming more advanced and versatile than ever before, thus making it necessary to adopt new techniques to enhance their performance. Machine Learning (ML), a branch of artificial intelligence, is a method of data analysis that automates analytical model building with minimal human intervention. The potential for ML to solve unpredictable and non-linear complex challenges is attracting researchers in the field of electromagnetics (EM), especially in antenna and antenna-based systems. Numerous antenna simulations, synthesis, and pattern recognition of radiations as well as non-linear inverse scattering-based object identifications are now leveraging ML techniques. Although the accuracy of ML algorithms depends on the availability of sufficient data and expert handling of the model and hyperparameters, it is gradually becoming the desired solution when researchers are aiming for a cost-effective solution without excessive time consumption. In this context, this paper aims to present an overview of machine learning, and its applications in Electromagnetics, including communication, radar, and sensing. It extensively discusses recent research progress in the development and use of intelligent algorithms for antenna design, synthesis and analysis, electromagnetic inverse scattering, synthetic aperture radar target recognition, and fault detection systems. It also provides limitations of this emerging field of study. The unique aspect of this work is that it surveys the state-of the art and recent advances in ML techniques as applied to EM.
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Guo, Chenyu, Hongxia Ye, Yi Zhou, Yonggang Xu, and Longxiang Wang. "Scaled Sea Surface Design and RCS Measurement Based on Rough Film Medium." Sensors 22, no. 16 (August 21, 2022): 6290. http://dx.doi.org/10.3390/s22166290.
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The electromagnetic (EM) scattering characteristics of the rough sea surface is very important for target surveying and detection in a sea environment. This work proposes a scaled sea surface designing method based on a rough thin-film medium. For the prototype sea surface, the permittivity is calculated with the seawater temperature, salinity, and EM wave frequency according to the Debye model. The scale film material is mixed with carbon black and epoxy, whose volume ratio is optimized with the genetic algorithm through the existing electromagnetic parameter library. This method can overcome the previous difficulties of adjusting the same permittivity of the prototype sea water. According to the EM scaled theory, the scaled geometric sample is numerically generated with the D-V spectrum for the given wind speed, and is fabricated using 3D printing to keep the similar seawater shape. Then, the sample is sprayed with a layer of film material for EM scattering measurement. The simulated and measured radar cross-section (RCS) results show good consistency for the prototype seawater and scaled materials, which indicates the proposed scaled method is a more efficient method to get the seawater scattering characteristics.
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Chungang, Jia, Guo Lixin, and Yang Pengju. "Time-Domain Physical Optics Method for the Analysis of Wide-Band EM Scattering from Two-Dimensional Conducting Rough Surface." International Journal of Antennas and Propagation 2013 (2013): 1–9. http://dx.doi.org/10.1155/2013/584260.
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Time-domain physical optics (TDPO) method is extended to investigate electromagnetic (EM) scattering from two-dimensional (2D) perfectly electrically conducting (PEC) rough surface in both time domain and frequency domain. The scheme requires relatively small amounts of computer memory and CPU time, and has advantage over the Kirchhoff Approximation (KA) method in obtaining transient response of rough surface by a program run. The 2D Gaussian randomly rough surface is generated by Monte Carlo method and then is partitioned into small triangle facets through the meshing preprocess. The accuracy of TDPO is validated by comparing the numerical results with those obtained by the KA method in both backward and specular directions. The transient response and its frequency distribution of radar cross section (RCS) from rough surface is shown, respectively. The scattering results from rough surface with different size in the specular direction are given. The influence of the root mean square height (σ) and correlation length (l) on electromagnetic scattering from PEC rough surface is discussed in detail. Finally, the comparisons of backscattering results at different incident angles are presented and analyzed.
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Alouges, Francois, Matthieu Aussal, and Emile Parolin. "FEM-BEM Coupling for Electromagnetism with the Sparse Cardinal Sine Decomposition,." ESAIM: Proceedings and Surveys 63 (2018): 44–59. http://dx.doi.org/10.1051/proc/201863044.
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This paper presents a FEM-BEM coupling method suitable for the numerical simulation of the electromagnetic scattering of objects composed of dielectric materials and perfect electric conduc- tors. The originality of the approach lies in part in the use of the newly proposed Sparse Cardinal Sine Decomposition SCSD) method for the BEM part of the computation and the fact that the simulation software is almost entirely written in MATLAB. The performance of the method is illustrated by the computation of the electromagnetic scattering by an UAV-like object with two RAM regions proposed in the workshop ISAE EM 2016.
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Gansen, A., M. El Hachemi, S. Belouettar, O. Hassan, and K. Morgan. "A 3D Unstructured Mesh FDTD Scheme for EM Modelling." Archives of Computational Methods in Engineering 28, no. 1 (January 17, 2020): 181–213. http://dx.doi.org/10.1007/s11831-019-09395-z.
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AbstractThe Yee finite difference time domain (FDTD) algorithm is widely used in computational electromagnetics because of its simplicity, low computational costs and divergence free nature. The standard method uses a pair of staggered orthogonal cartesian meshes. However, accuracy losses result when it is used for modelling electromagnetic interactions with objects of arbitrary shape, because of the staircased representation of curved interfaces. For the solution of such problems, we generalise the approach and adopt an unstructured mesh FDTD method. This co-volume method is based upon the use of a Delaunay primal mesh and its high quality Voronoi dual. Computational efficiency is improved by employing a hybrid primal mesh, consisting of tetrahedral elements in the vicinity of curved interfaces and hexahedral elements elsewhere. Difficulties associated with ensuring the necessary quality of the generated meshes will be discussed. The power of the proposed solution approach is demonstrated by considering a range of scattering and/or transmission problems involving perfect electric conductors and isotropic lossy, anisotropic lossy and isotropic frequency dependent chiral materials.
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Shi, Liping, Qinghe Zhang, Shihui Zhang, Chao Yi, and Guangxu Liu. "Electromagnetic Response Prediction of Reflectarray Antenna Elements Based on Support Vector Regression." Applied Computational Electromagnetics Society 35, no. 12 (February 15, 2021): 1519–24. http://dx.doi.org/10.47037/2020.aces.j.351210.
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In this letter, support vector regression (SVR) is used to predict the electromagnetic (EM) response of a complex shaped reflectarray (RA) unit cell. The calculation of the scattering coefficients of passive RA elements with periodic intervals is firstly transformed into a regression estimation problem, and then an analysis model is established by SVR to quickly predict the EM response of the unit cells. To this end, the full-wave (FW) simulation software is used to obtain a set of random samples of the scattering coefficient matrix of the RA antenna unit cell, which is used for SVR training. Under the same conditions, the radial basis function network (RBFN) is also used to predict the EM response of the elements, and the comparison results show the effectiveness and accuracy of the proposed method.
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Massa, Andrea, Arianna Benoni, Pietro Da Rù, Sotirios K. Goudos, Baozhu Li, Giacomo Oliveri, Alessandro Polo, Paolo Rocca, and Marco Salucci. "Designing Smart Electromagnetic Environments for Next-Generation Wireless Communications." Telecom 2, no. 2 (May 12, 2021): 213–21. http://dx.doi.org/10.3390/telecom2020014.
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The design of a smart electromagnetic (EM) environment for next-generation wireless communication systems is addressed in this work. The proposed approach aims at synthesizing a desired EM field distribution over a target region, where the receiving terminals are located, through the opportunistic exploitation of the complex scattering interactions between the EM field generated by a reconfigurable primary source and the objects/scatterers present in the environment, which behave as application-driven passive metastructures. The effectiveness and the potentialities of the proposed design methodology are assessed with a proof-of-concept numerical result obtained by means of advanced and reliable simulation tools.
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Walker, P. W., and G. F. West. "A robust integral equation solution for electromagnetic scattering by a thin plate in conductive media." GEOPHYSICS 56, no. 8 (August 1991): 1140–52. http://dx.doi.org/10.1190/1.1443133.
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An integral equation solution for electromagnetic (EM) scattering by a thin plate robustly models scattering in either perfectly resistive, very resistive, or conducting host media. Because the solution is not restricted to modeling certain ranges of host conductivity, it can be used to model scattering over the large ranges in conductivity encountered in geophysics. The solution is developed around a pair of coupled integral equations for the scattering distributions on the plate. In one equation, the scattering distribution is the scalar potential set up by the scattered charge distribution. In the other, it is the component of the scattered magnetic field perpendicular to the plate. The equations are solved numerically using the Galerkin method with simple polynomial basis functions. To find the fields scattered by the conductor, the scattered current density is first calculated from the scalar potential and the magnetic field. The scattered fields can then be found by integrating over the scattered current density. To test the solution, we model horizontal loop EM responses with our solution and compare the results with those from two established integral equation solutions. One of these solutions models pure induction and is used to test our solution when the host is perfectly resistive. Agreement with this solution is very good. Comparisons with the other solution, an electric field integral equation, tests our solution when the host medium is conductive. Agreement with the latter solution is good where induction is not too strong: i.e., where the electric‐field solution is known to work well. Our solution therefore can accurately model EM scattering by a plate in a host medium with any conductivity.
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Meng, Xiao, Li-xin Guo, and Tian-qi Fan. "The Investigation of EM Scattering from the Time-Varying Overturning Wave Crest Model by the IEM." Physics Research International 2016 (April 28, 2016): 1–8. http://dx.doi.org/10.1155/2016/3274147.
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Investigation of the electromagnetic (EM) scattering of time-varying overturning wave crests is a worthwhile endeavor. Overturning wave crest is one of the reasons of sea spike generation, which increases the probability of false radar alarms and reduces the performance of multitarget detection in the environment. A three-dimensional (3D) time-varying overturning wave crest model is presented in this paper; this 3D model is an improvement of the traditional two-dimensional (2D) time-varying overturning wave crest model. The integral equation method (IEM) was employed to investigate backward scattering radar cross sections (RCS) at various incident angles of the 3D overturning wave crest model. The super phenomenon, where the intensity of horizontal polarization scattering is greater than that of vertical polarization scattering, is an important feature of sea spikes. Simulation results demonstrate that super phenomena may occur in some time samples as variations in the overturning wave crest.
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Kong, Wei-Bin, Hou-Xing Zhou, Wei-Dong Li, Guang Hua, and Wei Hong. "The MLFMA Equipped with a Hybrid Tree Structure for the Multiscale EM Scattering." International Journal of Antennas and Propagation 2014 (2014): 1–6. http://dx.doi.org/10.1155/2014/281303.
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We present an efficient strategy for reducing the memory requirement for the near-field matrix in the multilevel fast multipole algorithm (MLFMA) for solving multiscale electromagnetic (EM) scattering problems. A multiscale problem can obviously lower the storage efficiency of the MLFMA for the near-field matrix. This paper focuses on overcoming this shortcoming to a certain extent. A hybrid tree structure for the MLFMA that possesses two kinds of bottom-layer boxes with different edge sizes will be built to significantly reduce the memory requirement for the near-field matrix in the multiscale case compared with the single-tree-structure technique. Several numerical examples are provided to demonstrate the efficiency of the proposed scheme in the multiscale EM scattering.
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Cheng, Yu, Li-Ye Xiao, Le-Yi Zhao, Ronghan Hong, and Qing Huo Liu. "A 3-D Full Convolution Electromagnetic Reconstruction Neural Network (3-D FCERNN) for Fast Super-Resolution Electromagnetic Inversion of Human Brain." Diagnostics 12, no. 11 (November 14, 2022): 2786. http://dx.doi.org/10.3390/diagnostics12112786.
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Three-dimensional (3-D) super-resolution microwave imaging of human brain is a typical electromagnetic (EM) inverse scattering problem with high contrast. It is a challenge for the traditional schemes based on deterministic or stochastic inversion methods to obtain high contrast and high resolution, and they require huge computational time. In this work, a dual-module 3-D EM inversion scheme based on deep neural network is proposed. The proposed scheme can solve the inverse scattering problems with high contrast and super-resolution in real time and reduce a huge computational cost. In the EM inversion module, a 3-D full convolution EM reconstruction neural network (3-D FCERNN) is proposed to nonlinearly map the measured scattered field to a preliminary image of 3-D electrical parameter distribution of the human brain. The proposed 3-D FCERNN is completely composed of convolution layers, which can greatly save training cost and improve model generalization compared with fully connected networks. Then, the image enhancement module employs a U-Net to further improve the imaging quality from the results of 3-D FCERNN. In addition, a dataset generation strategy based on the human brain features is proposed, which can solve the difficulty of human brain dataset collection and high training cost. The proposed scheme has been confirmed to be effective and accurate in reconstructing the distribution of 3-D super-resolution electrical parameters distribution of human brain through noise-free and noisy examples, while the traditional EM inversion method is difficult to converge in the case of high contrast and strong scatterers. Compared with our previous work, the training of FCERNN is faster and can significantly decrease computational resources.
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Funaro, Daniele, and Eugene Kashdan. "Simulation of electromagnetic scattering with stationary or accelerating targets." International Journal of Modern Physics C 26, no. 07 (April 30, 2015): 1550075. http://dx.doi.org/10.1142/s0129183115500758.
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The scattering of electromagnetic waves by an obstacle is analyzed through a set of partial differential equations combining the Maxwell's model with the mechanics of fluids. Solitary type EM waves, having compact support, may easily be modeled in this context since they turn out to be explicit solutions. From the numerical viewpoint, the interaction of these waves with a material body is examined. Computations are carried out via a parallel high-order finite-differences code. Due to the presence of a gradient of pressure in the model equations, waves hitting the obstacle may impart acceleration to it. Some explicative 2D dynamical configurations are then studied, enabling the simulation of photon-particle iterations through classical arguments.
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Lu, Guizhen, Zhonghang Duan, Hongcheng Yin, Zhihe Xiao, and Jing Zhang. "Determining the Effective Electromagnetic Parameters of Photonic Crystal by Phase Unwrapping and Denoising Method." International Journal of Antennas and Propagation 2019 (July 3, 2019): 1–10. http://dx.doi.org/10.1155/2019/8513150.
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The electromagnetic parameters of the dispersion material and metamaterial are vital in the engineering. The phase unwrapping method is proposed to deal with the phase ambiguity of the transmission and reflection method in electromagnetic (EM) parameters extraction. The computed results demonstrate that the proposed method can give the correct effective parameters. In dealing with scattering parameters with noise, the wavelet transform method is utilized to remove the noise added to the scattering parameters. The simulated results show that the correct material parameters can be obtained by wavelet denoising method. Finally, the proposed method is used to extract the parameters of the photonic crystal. The effective parameter gives a different aspect in explanation to the function for the photonic crystal.
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Su, Jianxun, Yao Lu, Zengrui Li, Rongrong Zhang, and Yaoqing (Lamar) Yang. "A Wideband and Polarization-Independent Metasurface Based on Phase Optimization for Monostatic and Bistatic Radar Cross Section Reduction." International Journal of Antennas and Propagation 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/7595921.
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A broadband and polarization-independent metasurface is analyzed and designed for both monostatic and bistatic radar cross section (RCS) reduction in this paper. Metasurfaces are composed of two types of electromagnetic band-gap (EBG) lattice, which is a subarray with “0” or “π” phase responses, arranged in periodic and aperiodic fashions. A new mechanism is proposed for manipulating electromagnetic (EM) scattering and realizing the best reduction of monostatic and bistatic RCS by redirecting EM energy to more directions through controlling the wavefront of EM wave reflected from the metasurface. Scattering characteristics of two kinds of metasurfaces, periodic arrangement and optimized phase layout, are studied in detail. Optimizing phase layout through particle swarm optimization (PSO) together with far field pattern prediction can produce a lot of scattering lobes, leading to a great reduction of bistatic RCS. For the designed metasurface based on optimal phase layout, a bandwidth of more than 80% is achieved at the normal incidence for the −9.5 dB RCS reduction for both monostatic and bistatic. Bistatic RCS reduction at frequency points with exactly 180° phase difference reaches 17.6 dB. Both TE and TM polarizations for oblique incidence are considered. The measured results are in good agreement with the corresponding simulations.
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Sui, Ran, Junjie Wang, Dejun Feng, and Yong Xu. "Full-polarization radar target feature modulation based on active polarization conversion metasurface." Journal of Applied Physics 132, no. 17 (November 7, 2022): 174903. http://dx.doi.org/10.1063/5.0107643.
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Electromagnetic (EM) metasurfaces comprising artificially designed subwavelength unit cells have drawn considerable attention due to the EM properties beyond the limits of natural materials. As one of the representative structures, active polarization conversion metasurface (APCM) is switchable by loading active components. It provides great freedom to manipulate the polarization state of EM waves. However, the current research mainly focused on the application of communication and paid less attention to the radar effect of APCM. APCM redistributes electromagnetic wave energy in multi-polarization channels, so it will have great application potential in polarimetric radar. Herein, based on the fully polarimetric radar one-dimensional high resolution range profile, the radar effect of time-modulated metasurface is studied. For this purpose, a method of target scattering mechanisms manipulation and a polarization-insensitive structure of APCM are proposed. The amplitude-phase joint modulation method is specifically analyzed in detail. The distance transformation and virtual multi-target phenomena are further discovered. Virtual targets along the distance dimension are generated in multi-polarization channels, while the scattering mechanisms of k-order targets are effectively manipulated. The relationship between the target scattering matrix and the modulation parameters is obtained. It may provide an effective method for the application of active metasurface in fully polarimetric radars.
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Li, Jinxing, Min Zhang, Ye Zhao, and Wangqiang Jiang. "Efficient Numerical Full-Polarized Facet-Based Model for EM Scattering from Rough Sea Surface within a Wide Frequency Range." Remote Sensing 11, no. 1 (January 3, 2019): 75. http://dx.doi.org/10.3390/rs11010075.
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A full-polarized facet based scattering model (FPFSM) for investigating the electromagnetic (EM) scattering by two-dimensional electrically large sea surfaces with high efficiency at high microwave bands is proposed. For this method, the scattering field over a large sea facet in a diffuse scattering region is numerically deduced according to the Bragg scattering mechanism. In regard to near specular directions, a novel approach is proposed to calculate the scattered field from a sea surface based on the second order small slope approximation (SSA-II), which saves computer memory considerably and is able to analyze the EM scattering by electrically large sea surfaces. The feasibility of this method in evaluating the radar returns from the sea surface is proved by comparing the normalized radar cross sections (NRCS) and the Doppler spectrum with the SSA-II. Then NRCS results in monostatic and bistatic configurations under different polarization states, scattering angles and wind speeds are analyzed as well as the Doppler spectrum at Ka-band. Numerical results show that the FPFSM is a reliable and efficient method to analyze the full-polarized scattering characteristics from electrically large sea surface within a wide frequency range.
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Song, Yoonho, Hee Joon Kim, and Ki Ha Lee. "An integral equation representation of wide‐band electromagnetic scattering by thin sheets." GEOPHYSICS 67, no. 3 (May 2002): 746–54. http://dx.doi.org/10.1190/1.1484517.
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An efficient, accurate numerical modeling scheme has been developed, based on the integral equation solution to compute electromagnetic (EM) responses of thin sheets over a wide frequency band. The thin‐sheet approach is useful for simulating the EM response of a fracture system in the earth. The focus of this development has been the accuracy of the numerical solution over a wide‐band frequency range of up to 100 MHz. The effect of displacement currents is included to correctly evaluate high‐frequency EM scattering. Currently, EM responses of two thin sheets with different geometrical and electrical properties embedded in a three‐layer earth can be modeled over a frequency band of 10−3 to 108 Hz. The layered earth and the sheets can be electrically dispersive, an important feature that allows analysis of frequency‐dependent characteristics of the model under investigation. The source field can be generated by a remote or local electric or magnetic dipole located on the surface or in a borehole. A plane‐wave source can also be used, and numerical analyses have been made for magnetotellurics and the high‐frequency impedance method.
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Yang, Wei, and Cong-hui Qi. "An Efficient High-Frequency Method to Compute EM Scattering of a Target on Rough Surface." Frequenz 72, no. 7-8 (June 26, 2018): 385–90. http://dx.doi.org/10.1515/freq-2017-0108.
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Abstract The physical optics and shooting and bouncing rays method are combined to rapidly compute the electromagnetic (EM) scattering from electrically large three- dimensional targets on a dielectric rough surface. To avoid modeling the rough surface of infinite extent, image theory is first used to account for the EM interactions between the target and the infinite planar surface. Next, the dielectric rough surface is accounted for by multiplying the Fresnel reflection coefficient with a roughness coefficient. In this way, only the target needs to be modeled. Thus, the proposed method can reduce significantly the computational costs and achieve a reasonable accuracy for the composite scattering problem, such as a ship-sea model.
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Liodakis, George S., Theodoros N. Kapetanakis, Melina P. Ioannidou, Anargyros T. Baklezos, Nikolaos S. Petrakis, Christos D. Nikolopoulos, and Ioannis O. Vardiambasis. "Electromagnetic Wave Scattering by a Multiple Core Model of Composite Cylindrical Wires at Oblique Incidence." Applied Sciences 12, no. 19 (October 10, 2022): 10172. http://dx.doi.org/10.3390/app121910172.
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A complex cylindrical structure consisting of a group of parallel stratified circular lossy dielectric cylinders, embedded in a dielectric circular cylindrical region and surrounded by unbounded dielectric space, is considered in this paper. The scattering of electromagnetic (EM) plane waves by the aforementioned configuration was studied; the EM waves impinged obliquely upon the structure and were arbitrarily polarized. The formulation used was based on the boundary-value approach coupled with the generalized separation of variables method. The EM field in each region of space was expanded in cylindrical wave-functions. Furthermore, the translational addition theorem of these functions was applied in order to match the EM field components on any cylindrical interface and enforce the boundary conditions. The end result of the analysis is an infinite set of linear algebraic equations with the wave amplitudes as unknowns. The system is solved by the truncation of series and unknowns and then matrix inversion; thus, we provide a semi-analytical solution for the scattered far-field and, as a consequence, for the scattering cross section of the complex cylindrical structure. The numerical results focus on calculations of the electric- and magnetic-field intensity of the far-field as well as of the total scattering cross section of several geometric configurations that fall within the aforementioned general structure. The effect of the geometrical and electrical characteristics of the structure on the scattered field was investigated. Specifically, the cylinders’ size and spacing, their conductivity and permittivity as well as the incidence direction were modified in order to probe how these variations are imprinted on scattering. Moreover, comparisons with previously published results, as well as convergence tests, were performed; all tests and comparisons proved to be successful.
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Zhao, Ye, Peng-Ju Yang, Xin-Cheng Ren, and Xiao-Min Zhu. "Rapid Simulation of Temporal-Spatial Correlated 3D Sea Clutter." International Journal of Antennas and Propagation 2019 (December 24, 2019): 1–9. http://dx.doi.org/10.1155/2019/9705406.
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Due to the difficulties in actual measurement of sea clutter and uncertainties of experimental data, the electromagnetic (EM) scattering model becomes a better alternative means to acquire the sea clutter. However, the EM scattering model still faces the problems of huge memory consumption and low-computational efficiency when dealing with the large size of sea surface or the long time case. Thus, this paper presents a statistical model to simulate the temporal-spatial correlated three-dimensional (3D) sea clutter, which is based on the statistical properties obtained from the EM scattering model, such as probability density function and correlation function. The comparisons show that the texture feature, autocorrelation function, and PDF of the sea clutter simulated by the statistical model have a good agreement with the results given by the EM model. Furthermore, the statistical model is with high efficiency and can be used to simulate the large scene or long time temporal-spatial correlated 3D sea clutter.
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White, Benjamin S., Werner E. Kohler, and Leonard J. Srnka. "Random scattering in magnetotellurics." GEOPHYSICS 66, no. 1 (January 2001): 188–204. http://dx.doi.org/10.1190/1.1444894.
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Typical well logs show substantial variations of formation electrical resistivity over small spatial scales, down to the resolution of the logging tool. Using a plane stratified earth model, we examine the effects of this fine‐scale microstructure on scattering of the naturally occurring electromagnetic (EM) waves used in magnetotellurics. We show how 1-D magnetotelluric (MT) data may be viewed as arising statistically from a smoothed effective medium version of the resistivity‐depth profile. The difference between the data produced by the true medium and the effective medium is attributable to random scattering noise. This noise is fundamental to magnetotellurics and other diffusive‐wave EM exploration methods since it arises from the very small spatial scales that are usually ignored. The noise has unique statistical properties, which we characterize. We show that if scattering is the dominant noise source, a thin layer of increased resistivity at depth can be reliably detected only if the noise statistics are incorporated properly into the detection algorithm. This sets a new fundamental limit on the vertical detection capability of MT data. The theory agrees well with Monte Carlo simulations of MT responses from random resistivity microlayers.
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Li, Dongfang, Zhiqin Zhao, Yanwen Zhao, Yuan Huang, and Zaiping Nie. "A Modified Model for Electromagnetic Scattering of Sea Surface Covered with Crest Foam and Static Foam." Remote Sensing 12, no. 5 (March 1, 2020): 788. http://dx.doi.org/10.3390/rs12050788.
Full textAbstract:
With the increase of sea surface wind speed, whitecaps will appear on the sea surface. Generally, for Electromagnetic (EM) scattering of the foam-covered sea surface, medium-scale waves are used to replace the breaking waves of the real sea surface. Another treatment in computation is to adopt one of the whitecap coverages and fixed foam layer thickness. In fact, the evolution process of a breaking wave goes through two stages: stage A (crest foam) and stage B (static foam). In this paper, a geometric model of the sea surface covered with crest foam and static foam is established. The coverage ratio of stage A and stage B is proposed for the first time for a given sea state. In addition, different foam layer thickness distributions in each foam for various wind speeds are also considered. Based on the facet scattering theory of sea surface, this paper adopts the modified facet-based scattering model to deal with the scattering contribution of the sea surface and the effect of foam. Finally, in order to verify the accuracy of the geometric modeling and the scattering model of the sea surface, the EM backscattering of sea surface under different sea states are calculated. Simulation results show that the results of the proposed model are more consistent with the measured data than the results of the sea surface covered with individual crest foam or the sea surface covered with individual static foam.
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Jiang, Wang-Qiang, Liu-Ying Wang, Xin-Zhuo Li, Gu Liu, and Min Zhang. "Simulation of a Wideband Radar Echo of a Target on a Dynamic Sea Surface." Remote Sensing 13, no. 16 (August 11, 2021): 3186. http://dx.doi.org/10.3390/rs13163186.
Full textAbstract:
Unlike a generally rough ground surface, the sea surface varies over time. To analyze the impact of the motion of sea waves on the synthetic aperture radar (SAR) image of a target, the wideband echo simulation method based on a frequency domain is used. For the wideband echo, the electromagnetic (EM) scattering properties of the main frequency components are analyzed by the simulation method. Based on the EM scattering properties, the echo can be accurately simulated by using the inverse fast Fourier transformation (IFFT). Combined with the flight path of the radar, the echo of each pulse can be simulated to obtain the SAR image. The correct evaluation of the EM scattering properties is indispensable to the acquisition of an accurate SAR image. For complex targets, such as ships, the multiple scattering effects have a significant influence on the EM scattering properties. Thus, a rectangular wave beam-based geometrical optics and physical optics (GO/PO) method is introduced to calculate the EM scattering properties, which is more efficient than the traditional GO/PO. The GO/PO method is suitable to simulate SAR images in which the EM scattering properties of each pulse need to be calculated. With these methods, the SAR images of the target on the sea surface are simulated. Based on the comparison of the SAR images between a static and dynamic sea surface, it is found that the region corresponding to the target is blurred and the texture of the dynamic sea is blurrier. The impact of multiple scattering and sea wave motion on target recognition are also analyzed with the SAR images that were generated under different conditions. Some strong scattering points appear when multiple scattering effects are considered. It is also found that the texture of the SAR images, corresponding to the sea surface, changes with the synthetic aperture time.
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Yang, Shuai, Kuang Zhang, Xumin Ding, Guohui Yang, and Qun Wu. "Tailoring the scattering properties of coding metamaterials based on machine learning." EPJ Applied Metamaterials 8 (2021): 15. http://dx.doi.org/10.1051/epjam/2021006.
Full textAbstract:
Diverse electromagnetic (EM) responses of coding metamaterials have been investigated, and the general research method is to use full-wave simulation. But if we only care its scattering properties, it is not necessary to perform full-wave simulation, which is usually time-consuming. Machine learning has significantly impelled the development of automatic design and optimize coding matrix. Based on metamaterial particle that has multiple response and genetic algorithm which is coupled with the scattering pattern analysis, we can optimize the coding matrix quickly to tailor the scattering properties without conducting full-wave simulation a lot of times for optimization. Since the coding matrix control of each particle allow modulation of EM wave, various EM phenomena can be achieved easier. In this paper, we proposed two reflective unitcells with different reflection phase, and then a semi-analytical model is built up for unitcells. To tailor the scattering properties, genetic algorithm normally based on binary coding, is coupled with the scattering pattern analysis in order to optimize the coding matrix. Finally, simulation results are compared with the semi-analytical calculation results and it is found that the simulation results agree very well with the theoretical values.
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Dong, Chunlei, Xiao Meng, Lixin Guo, and Jiamin Hu. "3D Sea Surface Electromagnetic Scattering Prediction Model Based on IPSO-SVR." Remote Sensing 14, no. 18 (September 18, 2022): 4657. http://dx.doi.org/10.3390/rs14184657.
Full textAbstract:
An Improved Particle Swarm Optimization Algorithm-Support Vector Regression Machine (IPSO-SVR) prediction model is developed in this paper to predict the electromagnetic (EM) scattering coefficients of the three-dimensional (3D) sea surface for large scenes in real-time. At first, the EM scattering model of the 3D sea surface is established based on the Semi-Deterministic Facet Scattering Model (SDFSM), and the validity of SDFSM is verified by comparing with the measured data. Using the SDFSM, the data set of backscattering coefficients from 3D sea surface is generated for different polarizations as the training samples. Secondly, an improved particle swarm optimization algorithm is proposed by combining the Particle Swarm Optimization (PSO) and Genetic Algorithm (GA). The combined algorithm is utilized to optimize the parameters and train the SVR to build a regression prediction model. In the end, the extrapolated prediction for backscattering coefficients of the 3D sea surface is performed. The Root Mean Square Error (RMSE) of the IPSO-SVR-based prediction model is less than 1.2 dB, and the correlation coefficients are higher than 91%. And the prediction accuracy of the PSO-SVR-based, GA-SVR-based and IPSO-SVR-based prediction models is compared. The average RMSE of the PSO-SVR-based and GA-SVR-based prediction models is 1.4241 dB and 1.6289 dB, respectively. While the average RMSE of the IPSO-SVR-based prediction model is reduced to 1.1006 dB. Besides, the average correlation coefficient of the PSO-SVR-based and GA-SVR-based prediction models is 94.36% and 93.93%, respectively. While the average correlation coefficient of the IPSO-SVR-based prediction model reached 95.12%. It demonstrated that the IPSO-SVR-based prediction model can effectively improve the prediction accuracy compared with the PSO-SVR-based and GA-SVR-based prediction models. Moreover, the simulation time of IPSO-SVR-based prediction model is significantly decreased compared with the SDFSM, and the speedup ratio is greater than 15.0. Therefore, the prediction model in this paper has practical application in the real-time computation of sea surface scattering coefficients in large scenes.
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Su, Yarong, Yuanzhen Shi, Ping Wang, Jinglei Du, Markus B. Raschke, and Lin Pang. "Quantification and coupling of the electromagnetic and chemical contributions in surface-enhanced Raman scattering." Beilstein Journal of Nanotechnology 10 (February 25, 2019): 549–56. http://dx.doi.org/10.3762/bjnano.10.56.
Full textAbstract:
In surface-enhanced Raman scattering (SERS), both chemical (CE) and electromagnetic (EM) field effects contribute to its overall enhancement. However, neither the quantification of their relative contributions nor the substrate dependence of the chemical effect have been well established. Moreover, there is to date no understanding of a possible coupling between both effects. Here we demonstrate how systematically engineered silver and gold planar and nanostructured substrates, covering a wide range of field enhancements, provide a way to determine relative contributions of chemical and electromagnetic field-enhancement in SERS measurements of benzenethiol. We find a chemical enhancement of 2 to 14 for different vibrational resonances when referencing against a vibrational mode that undergoes minimal CE. The values are independent of substrate type and independent of the enhancement of the electromagnetic intensity in the range from 1 to 106. This absence of correlation between chemical and electromagnetic enhancement resolves several long-standing controversies on substrate and intensity dependence of the chemical enhancement and allows for a more systematic design of SERS substrates with desired properties.
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Ho, Ming Tsu. "Two-Dimensional Simulation of EM Scattering from a Rotating Circular Dielectric Cylinder." Applied Mechanics and Materials 284-287 (January 2013): 1007–11. http://dx.doi.org/10.4028/www.scientific.net/amm.284-287.1007.
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The computational results of the scattered electromagnetic (EM) fields from a rotating circular dielectric cylinder were presented in this paper. The method of characteristics (MOC) was applied in a two dimensional modified O-type grid system to the solutions of the time-dependent Maxwell equations. To accurately model the rotating cylinder under the illumination of EM pulse, the passing center swing back grids (PCSBG) technique is employed in cooperation with MOC to overcome the difficulty of grid distortion due to the rotational movement of the cylinder. A number of electric and magnetic field distributions over the whole computational space were demonstrated in a side-by-side fashion for the comparison of the scattered EM fields from rotating circular dielectric cylinder with those from the stationary one. The numerical results exhibit feasible trends.
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Shao, Yang, Zhen Peng, Kheng Hwee Lim, and Jin-Fa Lee. "Non-conformal domain decomposition methods for time-harmonic Maxwell equations." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 468, no. 2145 (April 4, 2012): 2433–60. http://dx.doi.org/10.1098/rspa.2012.0028.
Full textAbstract:
We review non-conformal domain decomposition methods (DDMs) and their applications in solving electrically large and multi-scale electromagnetic (EM) radiation and scattering problems. In particular, a finite-element DDM, together with a finite-element tearing and interconnecting (FETI)-like algorithm, incorporating Robin transmission conditions and an edge corner penalty term , are discussed in detail. We address in full the formulations, and subsequently, their applications to problems with significant amounts of repetitions. The non-conformal DDM approach has also been extended into surface integral equation methods. We elucidate a non-conformal integral equation domain decomposition method and a generalized combined field integral equation method for modelling EM wave scattering from non-penetrable and penetrable targets, respectively. Moreover, a plane wave scattering from a composite mockup fighter jet has been simulated using the newly developed multi-solver domain decomposition method.
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Srilatha, K., B. T. P. Madhav, J. Krishna, Y. V. N. R. Swamy Banothu, and Anil Badisa. "Design of electromagnetic cloak with sequentially connected rectangular split ring resonators for S-band applications." AIMS Electronics and Electrical Engineering 6, no. 4 (2022): 385–96. http://dx.doi.org/10.3934/electreng.2022023.
Full textAbstract:
<abstract> <p>An electromagnetic (EM) invisible cloak is designed and analyzed with serially interconnected split ring resonators (SRRs). The cloak consists of an array of a network of split ring resonators which operates at a 3 GHz resonating frequency. The split ring resonators are connected with transmission line and are wrapped around the cylindrical object. Cloak coupled with EM waves gets transferred around the cylindrical object and received to the other side of transmission. Scattering cross section (SCS) is analyzed for both cases, which results in the effect of resonance. The total scattering cross section of the cloaked object is reduced by using SRRs. The simulated and measured results are in great agreement with each other. The transmission-line-connected SRR cloak is useful for S-band applications specifically at 3 GHz resonance.</p> </abstract>
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Li, Jinxing, Min Zhang, Wangqiang Jiang, and Pengbo Wei. "Improved FBAM and GO/PO Method for EM Scattering Analyses of Ship Targets in a Marine Environment." Sensors 20, no. 17 (August 21, 2020): 4735. http://dx.doi.org/10.3390/s20174735.
Full textAbstract:
The combination of the fact-based asymptotic method (FBAM) and the geometrical optics and physical optics (GO/PO) hybrid method is an effective way to analyze the electromagnetic (EM) scattering from electrically large ship targets in a marine environment because it takes the multiple scattering of the ship targets into consideration as well as the coupling scattering field between the targets and the sea surface. However, regarding an electrically large marine scene that contains a large target, the occlusion judgement process for calculating the multiple scattering field and the coupling field makes it inefficient. To solve this problem, this paper proposes a physical mechanism-based improved method to reduce the invalid occlusion judgment between different patches on the composite ship–ocean scene, and this operation enhances the computational efficiency significantly. With the proposed method, radar cross section (RCS) results of different targets and composite ship–ocean scenes were calculated and compared with the original FBAM and GO/PO method. Numerical results showed that the proposed method had higher efficiency compared with the original method with the same good accuracy. In addition, synthetic aperture radar (SAR) images of a composite ship–ocean scene with different radar parameters and sea conditions were simulated with the proposed method for detection purpose. Finally, the proposed method was used to analyze the EM scattering characteristic of a marine environment with multiple ships.
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Liang, Pengfei, Qingyun Di, Qihui Zhen, Ruo Wang, Olalekan Fayemi, Changmin Fu, Da Lei, et al. "Electromagnetic telemetry simulation in vertical drillings." GEOPHYSICS 85, no. 6 (October 13, 2020): E207—E219. http://dx.doi.org/10.1190/geo2019-0568.1.
Full textAbstract:
Electromagnetic (EM) telemetry is one of the key research subjects that has increased application in transmitting real-time data between the borehole and surface during drilling. There are several methods that can be used to model an EM telemetry system, including the method of moments (MoM) and the electric field integral equation method. We have developed a pulse basis function for the MoM, which assists in the analytical estimation of thin wire kernel integrations and avoids singular problems when simulating current distributions. The scattering field is solved using the current distribution. We examine the method using a simple example of vertical drilling. In the model, a vertically placed drill string is driven through a layered earth model. The drill string represents a long, thin wire antenna with a source located near the drill bit. The validity of the method is confirmed by comparing our results to the analytical solution in a half-space model as well as the current distributions along the drill string derived from the proposed method with those derived from a commercial finite-element solver, COMSOL-Multiphysics. Furthermore, the efficiency of this method is demonstrated by comparing its computational costs with those of COMSOL. The simulated EM telemetry in a known geologic setting is then compared with a field data example. These comparisons show that the proposed method is accurate and efficient. Moreover, we develop insights into how the parameters needed for calculations alter current distributions along the drill string and the signal received at the surface. The proposed method is therefore useful for obtaining the optimal design parameters for EM telemetry systems.
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Roohani Ghehsareh, Hadi, Seyed Kamal Etesami, and Maryam Hajisadeghi Esfahani. "Numerical Investigation of Electromagnetic Scattering Problems Based on the Compactly Supported Radial Basis Functions." Zeitschrift für Naturforschung A 71, no. 8 (August 1, 2016): 677–90. http://dx.doi.org/10.1515/zna-2016-0070.
Full textAbstract:
AbstractIn the current work, the electromagnetic (EM) scattering from infinite perfectly conducting cylinders with arbitrary cross sections in both transverse magnetic (TM) and transverse electric (TE) modes is numerically investigated. The problems of TE and TM EM scattering can be mathematically modelled via the magnetic field integral equation (MFIE) and the electric field integral equation (EFIE), respectively. An efficient technique is performed to approximate the solution of these surface integral equations. In the proposed numerical method, compactly supported radial basis functions (RBFs) are employed as the basis functions. The radial and compactly supported properties of these basis functions substantially reduce the computational cost and improve the efficiency of the method. To show the accuracy of the proposed technique, it has been applied to solve three interesting test problems. Moreover, the method is well used to compute the electric current density and also the radar cross section (RCS) for some practical scatterers with different cross section geometries. The reported numerical results through the tables and figures demonstrate the efficiency and accuracy of the proposed technique.
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Linghu, Longxiang, Jiaji Wu, Zhensen Wu, and Xiaobing Wang. "Parallel Computation of EM Backscattering from Large Three-Dimensional Sea Surface with CUDA." Sensors 18, no. 11 (October 28, 2018): 3656. http://dx.doi.org/10.3390/s18113656.
Full textAbstract:
An efficient parallel computation using graphics processing units (GPUs) is developed for studying the electromagnetic (EM) backscattering characteristics from a large three-dimensional sea surface. A slope-deterministic composite scattering model (SDCSM), which combines the quasi-specular scattering of Kirchhoff Approximation (KA) and Bragg scattering of the two-scale model (TSM), is utilized to calculate the normalized radar cross section (NRCS in dB) of the sea surface. However, with the improvement of the radar resolution, there will be millions of triangular facets on the large sea surface which make the computation of NRCS time-consuming and inefficient. In this paper, the feasibility of using NVIDIA Tesla K80 GPU with four compute unified device architecture (CUDA) optimization strategies to improve the calculation efficiency of EM backscattering from a large sea surface is verified. The whole GPU-accelerated SDCSM calculation takes full advantage of coalesced memory access, constant memory, fast math compiler options, and asynchronous data transfer. The impact of block size and the number of registers per thread is analyzed to further improve the computation speed. A significant speedup of 748.26x can be obtained utilizing a single GPU for the GPU-based SDCSM implemented compared with the CPU-based counterpart performing on the Intel(R) Core(TM) i5-3450.
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Štumpf, Martin. "Pulsed Electromagnetic Field Transmission through a Small Rectangular Aperture: A Solution Based on the Cagniard–DeHoop Method of Moments." Algorithms 15, no. 6 (June 20, 2022): 216. http://dx.doi.org/10.3390/a15060216.
Full textAbstract:
Pulsed electromagnetic (EM) field transmission through a relatively small rectangular aperture is analyzed with the aid of the Cagniard–deHoop method of moments (CdH-MoM). The classic EM scattering problem is formulated using the EM reciprocity theorem of the time-convolution type. The resulting TD reciprocity relation is then, under the assumption of piecewise-linear, space–time magnetic-current distribution over the aperture, cast analytically into the form of discrete time-convolution equations. The latter equations are subsequently solved via a stable marching-on-in-time scheme. Illustrative examples are presented and validated using a 3D numerical EM tool.
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Song, Zhe, Xing Mu, and Hou-Xing Zhou. "High Performance Computing of Complex Electromagnetic Algorithms Based on GPU/CPU Heterogeneous Platform and Its Applications to EM Scattering and Multilayered Medium Structure." International Journal of Antennas and Propagation 2017 (2017): 1–12. http://dx.doi.org/10.1155/2017/9173062.
Full textAbstract:
The fast and accurate numerical analysis for large-scale objects and complex structures is essential to electromagnetic simulation and design. Comparing to the exploration in EM algorithms from mathematical point of view, the computer programming realization is coordinately significant while keeping up with the development of hardware architectures. Unlike the previous parallel algorithms or those implemented by means of parallel programming on multicore CPU with OpenMP or on a cluster of computers with MPI, the new type of large-scale parallel processor based on graphics processing unit (GPU) has shown impressive ability in various scenarios of supercomputing, while its application in computational electromagnetics is especially expected. This paper introduces our recent work on high performance computing based on GPU/CPU heterogeneous platform and its application to EM scattering problems and planar multilayered medium structure, including a novel realization of OpenMP-CUDA-MLFMM, a developed ACA method and a deeply optimized CG-FFT method. With fruitful numerical examples and their obvious enhancement in efficiencies, it is convincing to keep on deeply investigating and understanding the computer hardware and their operating mechanism in the future.
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West, G. F., and R. N. Edwards. "A simple parametric model for the electromagnetic response of an anomalous body in a host medium." GEOPHYSICS 50, no. 12 (December 1985): 2542–57. http://dx.doi.org/10.1190/1.1441883.
Full textAbstract:
A simple approximate representation of the spectral response of an arbitrary kind of electromagnetic (EM) prospecting system to a small conductive target in a conductive environment has been derived. The representation contains the direct response from the layered host medium and the first‐order effects of eddy current induction, current channeling, magnetic induction, and the coupling between eddy current and magnetic inductions in the anomalous body, as modified by the host medium. The only significant computational task in the representation is evaluation of a few Green’s functions for the host medium. As a guide to establishing proper approximations, a fundamental study of integral equations is presented. Very simple solutions for the secondary or scattering sources which represent the EM effect of the body are obtained for a few basic cases. Equations for more general cases are complicated by additional terms in the Green’s functions which represent ac interaction between scattering sources and the host medium, the effects of layering in the host, or interactions between the different types of scattering sources. Through a supplementary study of the response of a conductive disk embedded in a conductive host to an axisymmetric field, the ac interaction between the host medium and scattering sources in the disk is shown to be relatively unimportant. Hence, interaction with layering in the host is also minimal. Green’s functions in the integral equation can consequently be simplified. The representation as a whole has been tested by comparing its predictions of the spectral form of a response with two published data sets, responses of a plate model in a conductive host. The fits for targets of moderate and large size, relative to the scale of the particular experiment, range from excellent to good qualitative resemblance. The representation should find application in making expensive numerical or analog model studies more useful and understandable to the field geophysicist, in converting real and model data between the time‐ and frequency‐domain formats, in constructing practical inverse algorithms, and in predicting the form of EM effects in induced polarization and magnetometric resistivity surveys.
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Mastorakis, Eleftherios, Panagiotis J. Papakanellos, Hristos T. Anastassiu, and Nikolaos L. Tsitsas. "Analysis of Electromagnetic Scattering from Large Arrays of Cylinders via a Hybrid of the Method of Auxiliary Sources (MAS) with the Fast Multipole Method (FMM)." Mathematics 10, no. 17 (September 5, 2022): 3211. http://dx.doi.org/10.3390/math10173211.
Full textAbstract:
The Method of Auxiliary Sources (MAS) is an established technique for the numerical solution of electromagnetic (EM) scattering and radiation problems. This paper presents a hybrid of MAS with the Fast Multipole Method (FMM), which provides a strategy for reducing the computational cost and for solving large-scale problems without notable accuracy loss (and in a reasonable time). The hybrid MAS-FMM scheme is applied to the problem of EM scattering from an arbitrarily large array of lossless/lossy dielectric cylinders. Numerical results are presented to verify the MAS and MAS-FMM schemes, as well as to illuminate the improvements stemming from the proposed hybridization (especially the ones regarding the associated complexity and computational cost). A few concluding remarks offer a summary of this work, along with a list of possible future extensions.
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Feng, Tiantian, and Lixin Guo. "Multiview ISAR Imaging for Complex Targets Based on Improved SBR Scattering Model." International Journal of Antennas and Propagation 2021 (January 25, 2021): 1–10. http://dx.doi.org/10.1155/2021/6615154.
Full textAbstract:
A novel multiview inverse synthetic aperture radar (ISAR) imaging method is proposed to simulate high-resolution and identifiable ISAR image of complex targets by handling large-angle and wide-bandwidth scattering data. The scattering data are simulated with the shooting and bouncing ray (SBR) method. The bidirectional ray-tracing algorithm is developed to reduce the computation time. Simulation results indicate that the improved method is efficient and reliable to calculate electromagnetic (EM) scattering of electrically large targets. To implement the multiview ISAR imaging method after data simulation, we divide the large-angle and wide-bandwidth scattering data into subaperture data and conduct ISAR image processing for each subaperture datum locally. Transforming each subaperture ISAR image to the global coordinate system and summing them together will produce the high-resolution ISAR image that is meaningful for the database set up for synthetic aperture radar automatic target recognition (SAR ATR). The final simulation ISAR images further validate the great performance of our scattering calculation algorithm and ISAR imaging method.
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Miao, Yuan Ben, Li Xin Guo, and An Qi Wang. "Simulation of EM Scattering from 3-D Target by MOM with Pulse Basis Function." Advanced Materials Research 383-390 (November 2011): 6449–54. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.6449.
Full textAbstract:
In this paper, electromagnetic (EM) scattering from a 3-D PEC target is simulated. The method of moments (MOM) with the pulse basis function and the point matching technique is presented to solve the magnetic field integral equation (MFIE). The flat triangular patch is applied to subdivide the surface of the 3-D target, and the surface unknowns are the arbitrary orthogonal unit vector of the triangular patch. Validity of this algorithm is shown by comparing the E plane and H plane radar cross section (RCS) from a sphere or a cylinder to those results of MOM with the RWG vector basis function. It is necessary to note that computational time of the algorithm presented in this paper is less than the MOM with the RWG(Rao Wilton Glisson) basis function.
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YANNOPAPAS, VASSILIOS. "DIRAC POINTS, TOPOLOGICAL EDGE MODES AND NONRECIPROCAL TRANSMISSION IN ONE-DIMENSIONAL METAMATERIAL-BASED COUPLED-CAVITY ARRAYS." International Journal of Modern Physics B 28, no. 02 (December 15, 2013): 1441006. http://dx.doi.org/10.1142/s0217979214410069.
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We show that topological frequency band structures emerge in one-dimensional (1D) electromagnetic (EM) lattices of metamaterial components without the application of an external magnetic field. Such lattices can be cavity arrays coupled with metamaterial elements which generate alternate positive and negative-phase hopping strengths. The topological nature of the band structure manifests itself by the occurrence of Dirac points in the band structure, by the emergence of edge modes in finite arrays as well as by a nonreciprocal scattering spectrum. Specific EM designs for demonstrating the above phenomena are discussed.
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Zhang, Xiao Hu, Qin Sun, and Shao Feng Xu. "Optimal Design of Multi-Layer Absorbent Honeycomb Cellular Composite Material Structure." Key Engineering Materials 723 (December 2016): 335–43. http://dx.doi.org/10.4028/www.scientific.net/kem.723.335.
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Next generation aircraft rely heavily on lightweight honeycomb composite structures for improved electromagnetic wave scattering and stealth capabilities. This paper investigated the optimal design and analysis methods of multi-layer absorbent honeycomb composite structures. The effective electromagnetic parameters of anisotropic object were calculated accompany with the formulation of reflectivity for incident wave. A genetic algorithm is employed to optimize the RCS of the absorptive honeycomb composite in desired angle range. The thickness and the volume fraction of absorptive materials are adopted to optimize the effective electromagnetic parameters under different polarized modes. Single and multi layer absorptive honeycomb composite were been studied. The results show that the thickness of the first absorptive layer plays a key role on the reflectivity of honeycomb structure. Therefore, it is advised to arrange the absorptive layers such that the EM absorption properties increases from outside to inside.
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Yang, Pei Gang, Zai Ping Nie, Shi Quan He, and Tao Qing. "Efficient Surface Integral Equation Using Travelling-Standing-Wave Vector Basis Function for Complex EM Scattering Problems." Applied Mechanics and Materials 325-326 (June 2013): 1498–501. http://dx.doi.org/10.4028/www.scientific.net/amm.325-326.1498.
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A new set of travelling-standing-wave (TSW) basis functions are proposed for curved triangular patch in this paper. This kind of bases is not only able to describe the standing component of induced surface current but also able to simulate the phase variation of induced current accurately. The authors used these basis functions to discrete surface integral equation (SIE) with a series of coarse meshes (even larger than 2λ) to calculate the electromagnetic (EM) scattering from the perfect electric conductor (PEC) targets with method of moment (MoM). Numerical experiments indicate that the MoM-TSW scheme even has more advantages than the MLFMA-CRWG scheme in the aspects of computational efficiency and memory storage.
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Zhao, Lei, and Gen Chen. "An Efficient Algorithm for EM Scattering from Anatomically Realistic Human Head Model Using Parallel CG-FFT Method." International Journal of Antennas and Propagation 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/495057.
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An efficient algorithm is proposed to analyze the electromagnetic scattering problem from a high resolution head model with pixel data format. The algorithm is based on parallel technique and the conjugate gradient (CG) method combined with the fast Fourier transform (FFT). Using the parallel CG-FFT method, the proposed algorithm is very efficient and can solve very electrically large-scale problems which cannot be solved using the conventional CG-FFT method in a personal computer. The accuracy of the proposed algorithm is verified by comparing numerical results with analytical Mie-series solutions for dielectric spheres. Numerical experiments have demonstrated that the proposed method has good performance on parallel efficiency.
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Song, Tao, Chuang-Ming Tong, Li-Li Cong, and Peng Peng. "Reliable Approach for EM Scattering Calculation from Sea Surface Covered with Foams Based on MFBM and VRT Theory." Mathematical Problems in Engineering 2018 (2018): 1–8. http://dx.doi.org/10.1155/2018/2035381.
Full textAbstract:
A reliable approach based on modified facet-based model and Vector Radiative Transfer theory is presented to calculate electromagnetic scattering from a particular electrically large sea surface superimposed with foams, which can handily give both monostatic and bistatic scattering results and could be applied to synthetic aperture radar imagery simulation. The facet model is derived from Fuks’ first-order small perturbation method function, and then the Kirchhoff model is introduced to revise the results in view of the dependency on cut-off wave number at near vertical incidence angles. Additionally, the contributions of foams are taken into consideration on the basis of Vector Radiative Transfer theory. The accuracy and superiority of this proposed approach are demonstrated in comparison with traditional facet model, which illustrates that the results of this approach agree better with experimental results. Moreover, several examples are given to verify that the proposed approach is of more significance at large incidence angles and high wind speed.