A higher-order dispersive finite-difference time-domain (FDTD) method has been proposed to accurately model cloaking structures. In the proposed method, the higher-order FDTD scheme with second-order accuracy in time ...
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A higher-order dispersive finite-difference time-domain (FDTD) method has been proposed to accurately model cloaking structures. In the proposed method, the higher-order FDTD scheme with second-order accuracy in time and fourth-order in space has combined with the shift operator algorithm. The exotic electromagnetic parameters of the cloaks are taken into account using shift operator based on dispersive FDTD method. The introduction of the higher-order algorithm would reduce the numerical dispersion of the FDTD method and guarantee a coarser grid during the simulation. Numerical results have indicated that the proposed method is more accurate than the available method maintaining the same grid size. Scattering width of different kinds of simplified cylindrical cloaks including thickness and loss is presented and this could serve for a further study on this subject. Crown Copyright (c) 2013 Published by Elsevier Ltd. All rights reserved.
We investigate the critical short-time scaling of the two-dimensional lattice phi(4) field theory with a Langevin dynamics. Starting from a "hot" initial configuration but with a small magnetization, the cri...
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We investigate the critical short-time scaling of the two-dimensional lattice phi(4) field theory with a Langevin dynamics. Starting from a "hot" initial configuration but with a small magnetization, the critical initial increase of the magnetization is observed through which we determine the critical point. From the short-time relaxation dynamics of various quantities at the critical point obtained, the dynamic critical exponents theta, z and the static exponent beta/nu are evaluated. In executing a Langevin simulation, an appropriate discretization method with respect to the time degree of freedom becomes essentially important to be adopted and we show that the well-know second-order form of discretized Langevin equation works well to investigate the short-time dynamics.
It has been shown that, in intensely noisy environments, adaptive algorithms based on higher-order statistics can enjoy better performance, as compared with the well known second-order least-mean-square (LMS) algorith...
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It has been shown that, in intensely noisy environments, adaptive algorithms based on higher-order statistics can enjoy better performance, as compared with the well known second-order least-mean-square (LMS) algorithm. By contrast, this advantage diminishes for low signal-to-noise ratio (SNR) levels, where the LMS algorithm outperforms. One remedy is to employ the LMS algorithm in conjunction with a higher-order adaptation algorithm, in a mixed mode. Least-mean kurtosis (LMK) is a higher-order algorithm that has been shown to be advantageous to use if the noise distribution is Gaussian or super-Gaussian. In this study, the authors propose the LMS/kurtosis algorithm, a stochastic gradient-based adaptive algorithm that is a combination of the LMS and the LMK algorithms. Simulation results demonstrate the privilege of the proposed algorithm, in comparison with its counterparts, for a wide range of noise distributions and SNR levels. This improvement is achieved in spite of a negligible increase in computational complexity. An analytical model is also derived for the mean weight as well as the weight-error covariance matrix, from which the mean-square-error behaviour of the algorithm can be predicted. Simulation results show the high accuracy of the derived model in different conditions.
In this paper, a higher-order shift operater (SO) FDTD scheme with second-order accuracy in time and fourth-order in space has been proposed to accurately model scattering of perfect electronic conductor coated with c...
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ISBN:
(纸本)9781510822023
In this paper, a higher-order shift operater (SO) FDTD scheme with second-order accuracy in time and fourth-order in space has been proposed to accurately model scattering of perfect electronic conductor coated with cloaking structures. Several different electromagnetic parameters of the cloaks are taken into account using SO-FDTD method. Numerical results indicate that the proposed method is more accuracy than the traditional method maintaining the same grid size. Scattering of different kinds of simplified cylindrical cloaks including thickness and loss are presented and could be served as further study on this subject.
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