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A Novel Piecewise Linear recursive convolution Approach for Dispersive Media Using the Finite-Difference Time-Domain Method

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IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION 2014年第5期62卷 2669-2678页

作者： Giannakis, Iraklis Giannopoulos, Antonios Univ Edinburgh Inst Infrastruct & Environm Sch Engn Edinburgh EH9 3JL Midlothian Scotland

Two novel methods for implementing recursively the convolution between the electric field and a time dependent electric susceptibility function in the finite-difference time domain (FDTD) method are presented. Both resulting algorithms are straightforward to implement and employ an inclusive susceptibility function which holds as special cases the Lorentz, Debye, and Drude media relaxations. The accuracy of the new proposed algorithms is found to be systematically improved when compared to existing standard piecewise linear recursive convolution (PLRC) approaches, it is conjectured that the reason for this improvement is that the new proposed algorithms do not make any assumptions about the time variation of the polarization density in each time interval;no finite difference or semi-implicit schemes are used for the calculation of the polarization density. The only assumption that these two new methods make is that the first time derivative of the electric field is constant within each FDTD time interval.

关键词： Complex-conjugate pole-residue pairs Debye Drude finite-difference time domain (FDTD) linear dispersive materials Lorentz PLRC recursive convolution TRC

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Application of multisection recursive convolution in 3D FETD-FABC simulations

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MICROWAVE AND OPTICAL TECHNOLOGY LETTERS 2008年第6期50卷 1651-1657页

作者： Cai, Yong Mias, Christos Univ Warwick Sch Engn Commun & Signal Proc Grp Appl Electromagnet & High Frequency Telecommun La Coventry CV4 7AL W Midlands England

The multisection recursive convolution (MS-RC) methodology is successfully applied to the finite element time domain floquet absorbing boundary condition modeling of doubly periodic structures. It is shown that late time instability, can be delayed by improving the accuracy of RC and it can be effectively avoided by employing extrapolation. (c) 2008 Wiley Periodicals, Inc.

关键词： time domain finite element method recursive convolution periodic structures

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Fast finite element time domain - Floquet modal absorbing boundary condition modelling of periodic structures using recursive convolution

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IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION 2007年第9期55卷 2550-2558页

作者： Cai, Yong Mias, Christos Univ Warwick Sch Engn Elect & Elect Div Commun & Signal Proc GrpAppl Electromagnet & Hig Coventry CV4 7AL W Midlands England

Finite element time domain (FETD) codes using a Floquet modal absorbing boundary condition to model scattering from periodic structures require the computation of time consuming convolution integrals. In this paper, we propose, for the first time, to reduce this computational burden using recursive convolution. recursive convolution is based on the ability to accurately approximate functions, over the entire computation time, using a summation of exponential functions. A novel approach, based on the exponential curve fitting facility of the commercially available software MATLAB, is employed. The time efficiency of the developed FETD code based on recursive convolution is demonstrated by comparing its computational speed with that of an FETD code employing standard convolution when modelling plane wave scattering from two-dimensional singly-periodic structures.

关键词： exponential curve fitting finite element methods recursive convolution time domain analysis

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Faster 3D finite element time domain - Floquet absorbing boundary condition modelling using recursive convolution and vector fitting

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IET MICROWAVES ANTENNAS & PROPAGATION 2009年第2期3卷 310-324页

作者： Cai, Y. Mias, C. Univ Warwick Sch Engn Coventry CV4 7AL W Midlands England

A recursive convolution (RC) based on the vector fitting (VF) method and triangular temporal basis functions is employed to compute the Floquet absorbing boundary condition (FABC) formulation in the vector 3D finite element time-domain (FETD) modelling of doubly periodic structures. This novel implementation (VF-RC-FETD-FABC) results in significantly lower computation time requirements than the standard convolution (SC) implementation. The numerical examples presented show a reduction in computation time requirements by a factor of at least 3.5. In addition, a time window in excess of 50 000 time steps is recorded over which practically stable results are obtained. This temporal window is sufficiently large to allow the modelling of many practical problems. The results from four such problems are presented, confirming the accuracy and speed of the VF-RC-FETD-FABC software.

关键词： vector fitting convolution doubly periodic structures standard convolution Mathematical analysis recursive convolution Finite element analysis finite element time domain modelling three-dimensional modelling Floquet absorbing boundary condition triangular temporal basis functions Signal processing and detection finite element analysis time-domain analysis

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A constant recursive convolution technique for frequency dependent scalar wave equation based FDTD algorithm

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JOURNAL OF COMPUTATIONAL ELECTRONICS 2013年第4期12卷 752-756页

作者： Ozakin, M. Burak Aksoy, Serkan Gebze Inst Technol Dept Elect Engn Kocaeli Turkey

A scalar wave equation based recursive convolution finite-difference time-domain algorithm is developed for a frequency-dependent Debye medium in this paper. This algorithm is based on a recursive evaluation of a convolution integral in the time domain. A numerical example is presented for a problem of wide-band reflection from an air-water interface. The obtained results are compared with an analytical solution. The excellent agreement is observed between the numerical results. Memory and computational time advantages of the proposed method over Maxwell's equations based solution are also shown.

关键词： Dispersive medium Finite difference time domain method recursive convolution

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Stable recursive convolution for Channel Response Calculation with Causality Enforcement

Stable Recursive Convolution for Channel Response Calculatio...

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IEEE Electrical Design of Advanced Packaging

作者： Tsiklauri, Mikheil Zvonkin, Mikhail Dikhaminjia, Nana Fan, Jun Drewniak, James Missouri Univ Sci & Technol EMC Lab Rolla MO 65401 USA

ISBN: (纸本)9781467380997

Checking and enforcing causality of simulated or measured system data is a crucial step for obtaining valid results. Previously, several methods for both frequency and time domain have been proposed. This paper explores the time domain causality enforcement method, its effect on the frequency domain transfer function, and proposes modification of the recursive convolution algorithm for impulse responses with time domain enforced causality to ensure calculation stability.

关键词： Impulse response Transient simulations Causality checking Causality enforcement recursive convolution

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Calculation for Transient Radiation Field from Metallic Enclosure of GIS Based on Vector Fitting and recursive convolution

Calculation for Transient Radiation Field from Metallic Encl...

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2004 3rd International Conference on Computational Electromagnetics and Its Applications

作者： Liang Guishu Ran Huijuan Ji Changhu Dong Huaying School of Electrical Engineering North China Electric Power University Baoding Electrical Vocational and Technical College

ISBN: (纸本)0780385624

＜正＞A new method is proposed to calculate transient radiation field from the metallic enclosure of gas insulated substation（GIS）.The frequency-domain Green Function is firstly approximated using vector fitting,and can be written as the sum of exponential functions in time-domain;then the transient radiation field is directly calculated using recursive *** not only improves the accuracy and reduces the CPU time,but also avoids the conventional problems of FFT.A comparison between the numerical results and the measured results of a 125 kV GIS confirms the correctness and accuracy of this method

关键词： gas insulated substation（GIS） transient radiation field vector fitting recursive convolution

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Real-Time Image Super-Resolution Using recursive Depthwise Separable convolution Network

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IEEE ACCESS 2019年 7卷 99804-99816页

作者： Hung, Kwok-Wai Zhang, Zhikai Jiang, Jianmin Shenzhen Univ Coll Comp Sci & Software Engn Shenzhen 518000 Peoples R China

In recent years, deep convolutional neural networks (CNNs) have been widely used for image super-resolution (SR) to achieve a range of sophisticated performances. Despite the significant advancement made in CNNs, it is still difficult to apply CNNs to practical SR applications due to enormous computations of deep convolutions. In this paper, we propose two lightweight deep neural networks using depthwise separable convolution for the real-time image SR. Specifically, depthwise separable convolution divides the standard convolution into depthwise convolution and pointwise convolution to significantly reduce the number of model parameters and multiplication operations. Moreover, recursive learning is adopted to increase the depth and receptive field of the network in order to improve the SR quality without increasing the model parameters. Finally, we propose a novel technique called Super-Sampling (SS) to learn more abundant high-resolution information by over-sampling the output image followed by adaptive down-sampling. The proposed two models, named SSNet-M and SSNet, outperform the existing state-of-the-art real-time image SR networks, including SRCNN, FSRCNN, ESPCN, and VDSR, in terms of model complexity, and subjective and PSNR/SSIM evaluations on Set5, Set14, B100, Urban100, and Manga109.

关键词： Super-resolution depthwise separable convolution super-sampling recursive convolution

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High-order accurate FDTD schemes for dispersive Maxwell's equations in second-order form using recursive convolutions

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JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS 2018年 336卷 192-218页

作者： Jenkinson, M. J. Banks, J. W. Rensselaer Polytech Inst Dept Math Sci Troy NY 12180 USA

We propose a novel finite-difference time-domain (FDTD) scheme for the solution of Maxwell's equations in which linear dispersive effects are present. The method uses high-order accurate approximations in space and time for the dispersive Maxwell's equations written as a second-order vector wave equation with a time-history convolution term. The modified equation approach is combined with the recursive convolution (RC) method to develop high-order approximations accurate to any desired order in space and time. High-order-accurate centered approximations of the physical Maxwell interface conditions are derived for the dispersive setting in order to fully restore accuracy at discontinuous material interfaces. Second- and fourth-order accurate versions of the scheme are presented and implemented in two spatial dimensions for the case of the Drude linear dispersion model. The stability of these schemes is analyzed. Finally, our approach is also amenable to curvilinear numerical grids if used with an appropriate generalized Laplace operator. (C) 2018 Elsevier B.V. All rights reserved.

关键词： Dispersive Maxwell FDTD recursive convolution Wave equations

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Higher-Order convolution PML (CPML) for FDTD Electromagnetic Modeling

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IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION 2020年第8期68卷 6226-6231页

作者： Giannopoulos, Antonios Univ Edinburgh Inst Infrastruct & Environm Sch Engn Edinburgh EH9 3FG Midlothian Scotland

A new simple formulation for incorporating a higher-order perfectly matched layer (PML) stretching function within a convolution PML (CPML) implementation in finite-difference time-domain (FDTD) electromagnetic modeling codes is developed. Obtaining in closed form the corresponding time domain impulse response of the inverse of a number of higher-order PML stretching functions enables the efficient and simple implementation of such higher-order PMLs using recursive convolution, in the same way as it was introduced initially for the complex frequency shifted (CFS) PML. This new higher-order CPML exhibits excellent performance that is comparable to the performance shown by other higher-order PML formulations whilst it retains the advantage of a relatively simpler implementation.

关键词： Time-domain analysis Finite difference methods convolution Antennas Standards Frequency-domain analysis Numerical stability Absorbing boundary conditions finitedifference time-domain (FDTD) finite difference methods perfectly matched layer (PML) recursive convolution

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