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Discretization of Nonlinear Non-affine Time Delay Systems Based on Second-order Hold

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International Journal of Automation and computing 2014年第3期11卷 320-327页

作者： Yuan-Liang Zhang School of Mechanical Engineering Huaihai Institute of Technology Jiangsu Province Research and Development Institute of Marine Resources

When calculating the sampled-date representation of nonlinear systems second-order hold(SOH) assumption can be applied to improving the precision of the discretization results. This paper proposes a discretization method based on taylor series and the SOH assumption for the nonlinear systems with the time delayed non-affine input. The mathematical structure of the proposed discretization method is explored. This proposed discretization method can provide a precise and finite dimensional discretization model for the nonlinear time-delayed non-affine system by keeping the truncation order of the taylor series. The performance of the proposed discretization method is evaluated by doing the simulation using a nonlinear system with the time-delayed non-affine *** input signals, time-delay values and sampling periods are considered in the simulation to investigate the proposed *** simulation results demonstrate that the proposed method is practical and easy for time-delayed nonlinear non-affine *** comparison between SOH assumption with first-order hold(FOH) and zero-order hold(ZOH) assumptions is given to show the advantages of the proposed method.

关键词： Nonlinear system non-affine input discretization taylor series second-order hold(SOH).

Fast Multipole BEM for 3-D Elastostatic Problems with Applications for Thin Structures

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Tsinghua Science and Technology 2005年第1期10卷 67-75页

作者：赵丽滨姚振汉 Department of Engineering Mechanics Tsinghua University Beijing 100084 China

The fast multipole method (FMM) has been used to reduce the computing operations and mem- ory requirements in large numerical analysis problems. In this paper, the FMM based on taylor expansions is combined with the boundary element method (BEM) for three-dimensional elastostatic problems to solve thin plate and shell structures. The fast multipole boundary element method (FM-BEM) requires O(N) opera- tions and memory for problems with N unknowns. The numerical results indicate that for the analysis of thin structures, the FM-BEM is much more efficient than the conventional BEM and the accuracy achieved is sufficient for engineering applications.

关键词： boundary element method taylor series multipole expansion thin structures

Design of a Multifrequency Signal Parameter Estimation Method for the Distribution Network Based on HIpST

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Energy Engineering 2024年第3期121卷 729-746页

作者： Bin Liu Shuai Liang Renjie Ding Shuguang Li Tongliao Power Supply Company State Grid East Inner Mongolia Electric Power Co.Ltd.Tongliao028000China School of Electrical Engineering Northeast Electric Power UniversityJilin132012China

The application of traditional synchronous measurement methods is limited by frequent fluctuations of electrical signals and complex frequency components in distribution ***,it is critical to find solutions to the issues of multifrequency parameter estimation and synchronous measurement estimation accuracy in the complex environment of distribution *** utilizing the multifrequency sensing capabilities of discrete Fourier transform signals and taylor series for dynamic signal processing,a multifrequency signal estimation approach based on HT-IpDFT-STWLS(HIpST)for distribution networks is ***,by introducing the Hilbert transform(HT),the influence of noise on the estimation algorithm is ***,signal frequency components are obtained on the basis of the calculated signal envelope spectrum,and the interpolated discrete Fourier transform(IpDFT)frequency coarse estimation results are used as the initial values of symmetric taylor weighted least squares(STWLS)to achieve high-precision parameter estimation under the dynamic changes of the signal,and the method increases the number of discrete ***,the accuracy of this proposed method is verified by simulation *** show that this proposed method can accurately achieve the parameter estimation of multifrequency signals in distribution *** approach provides a solution for the application of phasor measurement units in distribution networks.

关键词： Discrete fourier transform taylor series hilbert transform multifrequency signal parameter estimation

A Contact SPH Method with High-Order Limiters for Simulation of Inviscid Compressible Flows

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Communications in Computational Physics 2013年第7期14卷 425-442页

作者： Xueying Zhang Haiyan Tian Leihsin Kuo Wen Chen College of Science Hohai UniversityNanjingJiangsu 210098P.R.China Department of Mathematics University of Southern MississippiHattiesburgMS 39406USA Department of Engineering Mechanics Hohai UniversityNanjingJiangsu 210098P.R.China

In this paper,we study a class of contact smoothed particle hydrodynamics(SPH)by introducing Riemann solvers and using high-order *** particular,a promising concept ofWENO interpolation as limiter is presented in the reconstruction *** physical values relating interactional particles used as the initial values of the Riemann problemcan be reconstructed by the taylor series *** contact solvers of the Riemann problem at contact points are incorporated in SPH *** order to keep the fluid density at the wall rows to be consistent with that of the inner fluid wall boundaries,several lines of dummy particles are placed outside of the solid walls,which are assigned according to the initial *** last,the method is applied to compressible flows with sharp discontinuities such as the collision of two strong shocks and the interaction of two blast waves and so *** numerical results indicate that the method is capable of handling sharp discontinuity and efficiently reducing unphysical oscillations.

关键词： Meshless method SPH method the Riemann solution high-order limiter taylor series

A NEW SINGULARITY EXTRACTION TECHNIQUE FOR TDEFIE

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Journal of Electronics(China) 2007年第5期24卷 686-689页

作者： Liu Feng Zhou Dongming Cai Mingjuan Ren Meng He 3iangguo College of Electronic Science and Engineering National University of Defense Technology Changsha 410073 China

A new singularity extraction technique is presented to calculate accurately the singular integrals in Time Domain Electric Field Integral Equation (TDEFIE).In singularity extraction pro- cedure,through the aid of the first order taylor series of time base function including time-retardation,the singularity of the integrand can be *** surface current density and backscattered far-field response of a conducting cube illuminated by a Gaussian plane wave is com- puted using the presented *** are made with the results obtained by the Inverse Discrete Fourier Transform (IDFT) of the frequency domain and the results obtained by using Ve- chinski's time averaging technique,which demonstrate that the presented method with this new time domain singularity extraction technique to solve TDEFIE is very accurate and stable.

关键词： Singularity extraction technique taylor series Time Domain Electric Field Integral Equation (TDEFIE)

A Modified max-log-MAP Decoding Algorithm for Turbo Decoding

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The Journal of China Universities of Posts and Telecommunications 2002年第1期9卷 7-12页

作者： ZOU Xue lan, FENG Guang zeng (Mobile Communication Lab, Nanjing University of Posts and Telecommunications,Nanjing 210003, P. R. China) Mobile Communication Lab Nanjing University of Posts and TelecommunicationsNanjing 210003 P. R. China

Turbo decoding is iterative decoding, and the MAP algorithm isoptimal in terms of performance in Turbo decoding. The log-MAPalgorithms is the MAP executed in the logarithmic domain, so it isalso optimal. Both the MAP and the log-MAP algorithm are complicatedfor implementation. The max-log MAP algorithm is de- Rived from thelog-MAP with approximation, which is simply compared with the log-MAPalgorithm but is subopti- Malin terms of performance. A modifiedmax-log-MAP algorithm is presented in this paper, based on the taylorseries of logarithm and exponent. Analysis and simulation resultsshow that modified max-log-MAP algorithm Outperforms the max-log-MAPalgorithm with almost the same complexity.

关键词： turbo code the log-MAP algorithm taylor series

Parameter estimation method based on parameter function surface

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Science China(Technological Sciences) 2013年第9期56卷 1485-1498页

作者： BAO WeiMin ZHANG XiaoQin ZHAO LiPing State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University College of Hydrology and Water Resources Hohai University

By analyzing the structure of the objective function based on error sum of squares and the information provided by the objective function, the essential problems in the current parameter estimation methods are summarized: (1) the information extracted from the objective function based on error sum of squares is unreasonable or even wrong for parameter estimation; and (2) the surface of the objective function based on error sum of squares is more complex than that of the parameter function, which indicates that the optimal parameter values should be searched on the surface of the parameter function instead of the objective function. This paper proposes the concept of sample intersection and demonstrates the uniqueness theorem of intersection point (namely the uniqueness of optimal parameter values). According to the characteristics of parameter function surface and taylor series expansion, a parameter estimation method based on the sample intersection information extracted from parameter function surface (PFS method) was constructed. The results of theoretical analysis and practical application show that the proposed PFS method can avoid the problems in the current automatic parameter calibration, and has fast convergence rate and good performance in parameter calibration.

关键词： parameter estimation objective function surface parameter function surface uniqueness theorem intersection taylor series

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High-order generalized screen propagator migration based on particle swarm optimization

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Applied Geophysics 2017年第1期14卷 64-72,189,190页

作者：何润尤加春刘斌王彦春邓世广张丰麒中国地质大学(北京) 地球物理与信息技术学院北京100083 中国石化石油工程地球物理有限公司胜利分公司山东东营257086 中国地质科学院北京100037 中国石化石油勘探开发研究院北京100083

Various migration methods have been proposed to image high-angle geological structures and media with strong lateral velocity variations; however, the problems of low precision and high computational cost remain unresolved. To describe the seismic wave propagation in media with lateral velocity variations and to image high-angle structures, we propose the generalized screen propagator based on particle swarm optimization （PSO-GSP）, for the precise fitting of the single-square-root operator. We use the 2D SEG/EAGE salt model to test the proposed PSO-GSP migration method to image the faults beneath the salt dome and compare the results to those of the conventional high-order generalized screen propagator （GSP） migration and split-step Fourier （SSF） migration. Moreover, we use 2D marine data from the South China Sea to show that the PSO-GSP migration can better image strong reflectors than conventional imaging methods.

关键词： particle swarm optimization generalized screen propagator taylor series seismic migration one-way wave operator

Discovery of New Terms Associated with the Navier-Stokes Momentum Balance Equation and Finding the Evidence of Its Inapplicability to Govern Fluid Flow in the Infinite Space

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Journal of Applied Mathematics and Physics 2022年第3期10卷 731-771页

作者： Nikolai Kislov Nano CVD Company Tampa Florida USA

Our modeling fluid flow, especially if the fluid is referred to as a gas, is established on mimicking each particle/molecule’s movement and then gathering that movement into macro quantities characterizing the fluid flow. It has resulted in discovering a new principle of the property (mass, momentum, and energy) balance in space. We named it the Ballistic Principle of the Property Balance in Space as described earlier in our publications. This paper uses a different scheme of defining a net rate of total property efflux than our original paper. Using this scheme, we formulated integro-differential forms of mass balance and momentum balance equations adapted to the incompressible fluid flow (gas flow with a mass-flow velocity less than 0.3 Ma) at the non-uniform temperature in the infinite gas space. We also investigated the analytical behavior of the integro-differential equations in the region bounding the point of singularity by applying the taylor series expansion method to transform the integro-differential mass and momentum balance equations into the corresponding vector differential equations. Then we compared them with the Navier-Stokes equations of mass and momentum conservation for an incompressible fluid. We were surprised to find that the Navier-Stokes momentum balance equation does not describe the fluid flow adequately. Particularly, it does not consider the momentum associated with the part of velocity acquired by each gas particle during its free path traveling in the body force field. Also, the Navier-Stokes momentum balance equation is silent about the influence of the temperature non-uniformity on the momentum balance. Finally, we have demonstrated that the Navier-Stokes equations are not applicable to govern fluid flow on R3 × [0, ∞).

关键词： Navier-Stokes Fluid Dynamics Fluid Flow Gas Flow Momentum taylor series