The Experts below are selected from a list of 8001 Experts worldwide ranked by ideXlab platform
Lubomir Brancik - One of the best experts on this subject based on the ideXlab platform.
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Convergence acceleration techniques for proposed numerical Inverse Laplace transform method
2016 24th Telecommunications Forum (TELFOR), 2016Co-Authors: N. Al-zubaidi R-smith, Lubomir BrancikAbstract:In this paper, novel convergence accelerating techniques are adapted onto the proposed hyperbolic numerical Inverse Laplace transform method (hyperbolic-NILT) and analyzed. This ID NILT method is based on the approximation of the Inverse kernel of the Laplace transform Bromwich integral exp(st). It is shown that with the use of the convergence accelerating algorithms onto the essence of the proposed NILT method, an enhancement on the core of the inversion is achieved, with relatively accurate and stable results, while preserving valuable time and memory. The algorithms are tested and their corresponding results are discussed, mainly regarding the accuracy, stability and computational efficiency. The experimental accuracy analysis tests are implemented in the universal MATLAB language with properly chosen Laplace transforms.
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On two-dimensional numerical Inverse Laplace transforms with transmission line applications
2016 Progress in Electromagnetic Research Symposium (PIERS), 2016Co-Authors: Nawfal Al-zubaidi R-smith, Lubomir BrancikAbstract:Continuous space-time systems, such as transmission lines (TL) with distributed parameters, are normally described by linear 2D partial differential equations, and hence in these cases it is very difficult or even impossible to obtain the space-time response analytically, which brings out the importance of utilizing numerical techniques [1, 2]. In this paper three 2D numerical Inverse Laplace transform (NILT) methods are presented, which have the capability of retrieving the space-time response in one single calculation step. Initially the selected 2D-NILT methods, which are devised based on either Fourier series or Pade approximation, are implemented and verified in the Matlab environment. The numerical methods are examined by the use of relevant test functions in the Laplace domain with pre-known originals. Furthermore, the 2D-NILT methods results are analysed from an electrical engineering point of view to observe their performance as for their accuracy, universality and stability. Following, there will be an application of these 2D-NILTs independently on a transmission line described by a Laplace model.
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Numerical Inverse Laplace Transforms for Electrical Engineering Simulation
MATLAB for Engineers - Applications in Control Electrical Engineering IT and Robotics, 2011Co-Authors: Lubomir BrancikAbstract:Numerical Inverse Laplace transform (NILT) methods are widely used in various scientific areas, especially for a solution of respective differential equations. In field of an electrical engineering many various approaches have been considered so far, but mostly for a single variable (1D NILT), see at least (Brancik, 1999, 2007b; Cohen, 2007; Valsa & Brancik, 1998; Wu at al., 2001) from plenty of papers. Much less attention was paid to multidimensional variable (nD NILT) methods, see e.g. (Hwang at al., 1983; Singhal at al., 1975), useful rather for more complicated electromagnetic systems. The 2D NILT methods, see e.g. (Brancik, 2005, 2007a, 2007b; Hwang & Lu, 1999), can be applied for a transmission line analysis, or nD NILT methods, n ≥ 2, for a nonlinear circuits analysis, if relevant Laplace transforms are developed through a Volterra series expansion, see e.g. (Brancik, 2010a, 2010b, Karmakar, 1980; Schetzen, 2006), to highlight at least a few applications. This paper is focused on the class of NILT methods based on complex Fourier series approximation, their error analysis, their effective algorithms development in a Matlab language, and after all, on their selected applications in field of electrical engineering to show practical usefulness of the algorithms.
Luisa D’amore - One of the best experts on this subject based on the ideXlab platform.
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Remarks on numerical algorithms for computing the Inverse Laplace transform
Ricerche di Matematica, 2014Co-Authors: Luisa D’amoreAbstract:Algorithms for computing the Inverse Laplace transform that consist essentially in choosing a series expansion for the original function are particularly effective in many cases and are widely used. The main purpose of this paper is to review these algorithms in the context of regularization. We relate this viewpoint to the design of reliable algorithms destined to be run on finite precision arithmetic systems.
Alberto Borghetti - One of the best experts on this subject based on the ideXlab platform.
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Inverse Laplace Transform of Sunde’s Formula for the Ground Impedance of Buried Cables
2019 IEEE International Conference on Environment and Electrical Engineering and 2019 IEEE Industrial and Commercial Power Systems Europe (EEEIC I&CPS, 2019Co-Authors: Fabio Tossani, Fabio Napolitano, Alberto BorghettiAbstract:The time-domain calculation of electromagnetic transients in multi-conductor lossy overhead lines and buried cables requires the evaluation of the transient ground resistance matrix. For the case of overhead lines, analytical expressions for the transient ground resistance obtained by solving the Inverse Laplace transform of Sunde's formula have been recently presented. This paper presents the expressions obtained by the analytical Inverse Laplace transform of Sunde's formula for the case of buried cables. The results provided by the proposed analytical expressions agree with those given by the numerical Inverse transform of Sunde's formula. The new expressions are adopted for the calculation of the per-unit-length voltage drop in a multiconductor underground line. The voltage drop waveforms are compared with those given by recently proposed time-domain analytical expressions that neglect displacement currents.
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Inverse Laplace transform of sunde s formula for the ground impedance of buried cables
International Conference on Environment and Electrical Engineering, 2019Co-Authors: Fabio Tossani, Fabio Napolitano, Alberto BorghettiAbstract:The time-domain calculation of electromagnetic transients in multi-conductor lossy overhead lines and buried cables requires the evaluation of the transient ground resistance matrix. For the case of overhead lines, analytical expressions for the transient ground resistance obtained by solving the Inverse Laplace transform of Sunde’s formula have been recently presented. This paper presents the expressions obtained by the analytical Inverse Laplace transform of Sunde’s formula for the case of buried cables. The results provided by the proposed analytical expressions agree with those given by the numerical Inverse transform of Sunde’s formula. The new expressions are adopted for the calculation of the per-unit-length voltage drop in a multiconductor underground line. The voltage drop waveforms are compared with those given by recently proposed time-domain analytical expressions that neglect displacement currents.
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Inverse Laplace Transform of the Ground Impedance Matrix of Overhead Lines
IEEE Transactions on Electromagnetic Compatibility, 2018Co-Authors: Fabio Tossani, Fabio Napolitano, Alberto BorghettiAbstract:This letter deals with the calculation in time domain of the transient ground resistance matrix of an overhead transmission line (TL). Each element of the matrix is evaluated by solving analytically the Inverse Laplace transform of the general integral expressions of the ground impedance in frequency domain proposed by Sunde. The presented expressions are suitable for the direct implementation in an electromagnetic transient program (e.g., EMTP-like ones) based on a time domain solution of the TL's equations.
Shinichiro Ohnuki - One of the best experts on this subject based on the ideXlab platform.
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time domain analysis of electromagnetic fields using the fast Inverse Laplace transform
Progress in Electromagnetic Research Symposium, 2016Co-Authors: Shinichiro Ohnuki, S Watanabe, K NagasawaAbstract:Time-domain analysis of electromagnetic fields is indispensable for developing target identification, designing microwave devices, studying optical properties of materials, and so on. Many commercial softwares based on time-domain solvers are available and they are useful for practical applications of industrial design and modeling. However, it is still difficult to evaluate accuracy and reliability, since reference solutions of time-domain responses are quite limited. In this presentation, time domain responses of scattered waves from canonical structures are investigated using the fast Inverse Laplace transform (FILT). In our method, the waves are firstly obtained in the complex frequency s domain. Next, the waves in the s domain are numerically transformed into the time domain using FILT. Our method has advantage to estimate and control computational error easily, and arbitrary sampling points in time can be selected. We demonstrate that time domain responses of scattered waves from canonical structures are computed for various shapes of the incident pulses and materials. Our results are reliable and highly accurate, and they are considered as reference solutions of time-domain electromagnetic fields.
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efficient analysis of electromagnetic fields for designing nanoscale antennas by using a boundary integral equation method with fast Inverse Laplace transform
Progress in Electromagnetics Research-pier, 2014Co-Authors: Seiya Kishimoto, Shinichiro Ohnuki, Yoshito Ashizawa, Tatsuichiro Okada, Katsuji NakagawaAbstract:In this paper, we investigate electromagnetic problems for nanoscale antennas by using a boundary integral equation method with fast Inverse Laplace transform. The antennas are designed for realizing ultra-fast and high-density magnetic recording. Characteristics of nanoscale antennas are discussed in terms of eigenmodes and time domain responses of electric flelds. Our computational method is highly e-cient and the computational cost can be reduced by selecting coarse time-step size and performing parallel computation.
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Time-domain analysis of electromagnetic problems for nanoscale objects by integral equation methods with fast Inverse Laplace transform
2013 USNC-URSI Radio Science Meeting (Joint with AP-S Symposium), 2013Co-Authors: Seiya Kishimoto, Shinichiro Ohnuki, Yoshito Ashizawa, Katsuji Nakagawa, Shao Ying Huang, Weng Cho ChewAbstract:Summary form only given: For ultra-fast and ultra-high density magnetic recording, all-optical magnetic recording has attracted attention. This state-of-the-art technology needs circularly polarized light. In this report, we propose a novel computational method to design the plasmonic antennas which generate localized circular polarized light for high-density recording. We will discuss characteristics of the antenna in terms of the time response of electromagnetic fields and Stokes parameters. Our proposed method is based on the combination of integral equation methods and fast Inverse Laplace transform (FILT). The integral equation method, the boundary integral equation method (BIEM) using the static approximation or Poggio-Miller-Chang-Harrigton-Wu-Tsai (PMCHWT) method, is considered and extended in the complex frequency. The electromagnetic fields in the complex frequency domain can be obtained by the integral equation methods and transformed into the time-domain by using fast Inverse Laplace transform (FILT). Our method can perform reliable and fast simulation, with the following advantages: (1) the computational error is easy to be controlled; (2) the solution at each observation time can be calculated independently; (3) the time step size can be selected as an arbitrary number; and (4) high parallel efficiency can be obtained.
Hongbin Zhan - One of the best experts on this subject based on the ideXlab platform.
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on different numerical Inverse Laplace methods for solute transport problems
Advances in Water Resources, 2015Co-Authors: Quanrong Wang, Hongbin ZhanAbstract:Numerical inversion is required when Laplace transform cannot be inverted analytically by manipulating tabled formulas of special cases. However, the numerical Inverse Laplace transform is generally an illposed problem, and there is no universal method which works well for all problems. In this study, we selected seven commonly used numerical Inverse Laplace transform methods to evaluate their performance for dealing with solute transport in the subsurface under uniform or radial flow condition. Such seven methods included the Stehfest, the de Hoog, the Honig–Hirdes, the Talbot, the Weeks, the Simon and the Zakian methods. We specifically investigated the optimal free parameters of each method, including the number of terms used in the summation and the numerical tolerance. This study revealed that some commonly recommended values of the free parameters in previous studies did not work very well, especially for the advection-dominated problems. Instead, we recommended new values of the free parameters for some methods after testing their robustness. For the radial dispersion, the de Hoog, the Talbot, and the Simon methods worked very well, regardless of the dispersion-dominated or advection-dominated situations. The Weeks method can be used to solve the dispersion-dominated problems, but not the advection-dominated problems. The Stehfest, the Honig–Hirdes, and the Zakian methods were recommended for the dispersion-dominated problems. The Zakian method was efficient, while the de Hoog method was time-consuming under radial flow condition. Under the uniform flow condition, all the methods could present somewhat similar results when the free parameters were given proper values for dispersion-dominated problems; while only the Simon method, the Weeks method, and the de Hoog method worked well for advection-dominated problems.
