A many-core parallel approach of the multilevel fast multipole algorithm (MLFMA) based on the Athread parallel programming model is presented on the homegrown many-core SW26010 CPU of China. In the proposed many-core ...
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A many-core parallel approach of the multilevel fast multipole algorithm (MLFMA) based on the Athread parallel programming model is presented on the homegrown many-core SW26010 CPU of China. In the proposed many-core implementation of MLFMA, the data access efficiency is improved by using data structures based on the structure of array. The adaptive workload distribution strategies are adopted on different MLFMA tree levels to ensure full utilization of computing capability and the scratchpad memory. A double buffering scheme is specially designed to make communication overlapped computation. The resulting Athread-based many-core implementation of the MLFMA is capable of solving real-life problems with over one million unknowns with a remarkable speedup. The capability and efficiency of the proposed method are analyzed through the examples of computing scattering by spheres and a practical aerocraft. Numerical results show that with the proposed parallel scheme, the total speedup ratios from 6.4 to 8.0 can be achieved, compared with the CPU master core.
In this study, a synthesis of the multilevel fast multipole algorithm (MLFMA) and the multiresolution (MR) preconditioning technique is presented for the analysis of scattering from homogeneous dielectric targets abov...
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In this study, a synthesis of the multilevel fast multipole algorithm (MLFMA) and the multiresolution (MR) preconditioning technique is presented for the analysis of scattering from homogeneous dielectric targets above a lossy half-space. The Poggio-Miller-Chang-Harrington-Wu-Tsai (PMCHWT) integral equation and the MLFMA are used for efficient analysis of scattering problems in half-space. The MR preconditioning technique is used to speed up the convergence rate of the iterative solver. The numerical results are presented to demonstrate that the proposed method is efficient for the scattering from homogeneous dielectric objects above a lossy half-space.
Iterative solution of large-scale scattering problems in computational electromagnetics with the multilevel fast multipole algorithm (MLFMA) requires strong preconditioners, especially for the electric-field integral ...
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Iterative solution of large-scale scattering problems in computational electromagnetics with the multilevel fast multipole algorithm (MLFMA) requires strong preconditioners, especially for the electric-field integral equation (EFIE) formulation. Incomplete LU (ILU) preconditioners are widely used and available in several solver packages. However, they lack robustness due to potential instability problems. In this study, we consider various ILU-class preconditioners and investigate the parameters that render them safely applicable to common surface integral formulations without increasing the O(n log n) complexity of MLFMA. We conclude that the no-fill ILU(0) preconditioner is an optimal choice for the combined-field integral equation (CFIE). For EFIE, we establish the need to resort to methods depending on drop tolerance and apply pivoting for problems with high condition estimate. We propose a strategy for the selection of the parameters so that the preconditioner can be used as a black-box method. Robustness and efficiency of the employed preconditioners are demonstrated over several test problems.
In order to accelerate the solution procedure of radiation problems using multilevel fast multipole algorithm, a novel precorrected method is presented in this letter. A rather small impedance matrix in the local regi...
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In order to accelerate the solution procedure of radiation problems using multilevel fast multipole algorithm, a novel precorrected method is presented in this letter. A rather small impedance matrix in the local region near the feed point is generated to evaluate the local surface current, which could approximately describe the characteristic near the feed point. Because the difference between unknown and the local currents is closer to the zero vectors than the unknown currents themselves, it does need fewer iteration steps using the difference as the unknown vector to get the solution. As is shown, this method could decrease the number of iterations and greatly reduce the time of solution.
We present electromagnetic optimizations by heuristic algorithms supported by approximate forms of the multilevel fast multipole algorithm (MLFMA). Optimizations of complex structures, such as antennas, are performed ...
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We present electromagnetic optimizations by heuristic algorithms supported by approximate forms of the multilevel fast multipole algorithm (MLFMA). Optimizations of complex structures, such as antennas, are performed by considering each trial as an electromagnetic problem that can be analyzed via MLFMA and its approximate forms. A dynamic accuracy control is utilized in order to increase the efficiency of optimizations. Specifically, in the proposed scheme, the accuracy is used as a parameter of the optimization. We show that the developed mechanism with dynamic accuracy control provides faster optimizations without deteriorating the quality of the final results in comparison to optimizations with full MLFMA.
The potential of the interpolative decomposition multilevel fast multipole algorithm (ID-MLFMA) on developing an effective preconditioning technique for multiscale, dynamic electromagnetic problems are analyzed. The p...
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The potential of the interpolative decomposition multilevel fast multipole algorithm (ID-MLFMA) on developing an effective preconditioning technique for multiscale, dynamic electromagnetic problems are analyzed. The preconditioner based on multilevel inverse-based ILU is developed for ID-MLFMA. The proposed preconditioning technique is investigated by numerical experiments on complex targets.
Circular-sectoral arrays of log-periodic (LP) antennas are presented for frequency-independent operation and beam-steering capability. Specifically, nonplanar trapezoidal tooth LP antennas are considered in a circular...
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Circular-sectoral arrays of log-periodic (LP) antennas are presented for frequency-independent operation and beam-steering capability. Specifically, nonplanar trapezoidal tooth LP antennas are considered in a circular array configuration, where closely spaced antennas occupy a sector of the circle. Electromagnetic interactions of the array elements, each of which is a complicated LP antenna structure, are rigorously computed with the multilevel fast multipole algorithm (MLFMA). Genetic algorithms (GAs) are also employed in combination with MLFMA for synthesis and design purposes. By optimizing the excitations of the array elements via GAs, beam-steering ability is achieved in addition to the broadband (nearly frequency-independent) characteristics of the designed arrays. Computational results are presented to demonstrate the important properties of LP arrays.
In this paper, several iterative methods with multilevel fast multipole algorithm (MLFMA) have been applied for solving large-scale scattering problems and compared with each other. The Bi-static RCS of four different...
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ISBN:
(纸本)9781424428014
In this paper, several iterative methods with multilevel fast multipole algorithm (MLFMA) have been applied for solving large-scale scattering problems and compared with each other. The Bi-static RCS of four different targets, involving both open and closed objects, are calculated. Bi-CGSTAB, GMRES and Flexible GMRES (FGMRES) are employed in these simulations, and their performance are demonstrated. Based on these numerical results, suggestions about choosing the appropriate iterative method for different scattering targets are proposed, in order to minimize the solution time.
Nested iterative solutions using full and approximate forms of the multilevel fast multipole algorithm (MLFMA) are presented for efficient analysis of electromagnetic problems. The developed mechanism is based on prec...
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ISBN:
(纸本)9788890701870
Nested iterative solutions using full and approximate forms of the multilevel fast multipole algorithm (MLFMA) are presented for efficient analysis of electromagnetic problems. The developed mechanism is based on preconditioning an iterative solution via another iterative solution, and this way, nesting multiple solutions as layers. The accuracy is systematically reduced from top to bottom by using the on-the-fly characteristics of MLFMA, as well as the iterative residual errors. As a demonstration, a three-layer strategy is presented, considering its parametrization for accelerating iterative solutions of perfectly conducting objects. We show that the strategy significantly reduces the solution time, especially for ill-conditioned matrix equations that are derived from the electric-field integral equation.
A parallel implementation of the multilevel fast multipole algorithm (MLFMA) is developed for fast and accurate solutions of electromagnetics problems involving complex plasmonic metamaterial structures. Composite obj...
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ISBN:
(纸本)9781479933433
A parallel implementation of the multilevel fast multipole algorithm (MLFMA) is developed for fast and accurate solutions of electromagnetics problems involving complex plasmonic metamaterial structures. Composite objects that consist of multiple penetrable regions, such as dielectric, lossy, and plasmonic parts, are formulated rigorously with surface integral equations and solved iteratively via MLFMA. Using the hierarchical strategy for the parallelization, the developed implementation is capable of simulating realistic structures discretized with millions of unknowns.
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