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A Fast Time-Domain algorithm for the Simulation of Switching Power Converters

IEEE TRANSACTIONS ON POWER ELECTRONICS 1990年第3期5卷 363-370页

作者： Luciano, Angelo M. Strollo, Antonio G. M. Univ Naples Dept Elect Via Claudio I-80125 Naples Italy

A new efficient algorithm for the simulation of switched-mode power converters is developed. A Chebyshev series expansion is employed to effectively solve the differential equations describing the system in each topology. The power of the new simulation technique lies both in the simple but accurate polynomial approximation for the state transition matrices and in the ability to explicitly obtain the instants at which the switching of the circuit topology takes place. The case of a rapidly varying input forcing function can also easily be analyzed. Examples illustrating the generality and the computational efficiency of the new algorithm are presented.

关键词： state transition matrix Series expansions Circuit topology Polynomial approximation power conversion unit simulating Simulation models algorithm simulation efficient algorithm Converters switched mode power supplies algorithms Computational efficiency step-down converter algorithm efficiency

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A new approach to modelling an unsteady free surface in boundary integral methods with application to bubble-structure interactions

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MATHEMATICS AND COMPUTERS IN SIMULATION 1997年第4期44卷 415-426页

作者： Tong, RP Univ Birmingham Sch Math & Stat Birmingham B15 2TT W Midlands England

The interaction of transient cavities in fluid flows with rigid boundaries is investigated numerically. The class of fluid motions considered here can be described by a velocity potential and a newly-developed fully three-dimensional boundary integral method is employed to compute the evolution of the free surface. Particular attention is given to the approximation of the surface velocities by radial basis function methods, thus avoiding some of the limitations of polynomial approximation. The efficiency of the algorithm is demonstrated through computed examples which show the interaction of buoyancy with the Bjerknes effect of a rigid boundary for the growth and collapse of transient cavities in a fluid.

关键词： Scattered data Buoyancy Surface velocity Fluid algorithm efficiency boundary integral method discrete data Radial basis function

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Sequential Nonparametric algorithm for Detecting Time Series Breakdown

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AUTOMATION AND REMOTE CONTROL 2021年第12期82卷 2204-2212页

作者： Chervova, A. A. Filaretov, G. F. Zineddine, Bouchaala Natl Med Res Ctr Childrens Hematol Oncol & Immuno Moscow 117198 Russia Natl Res Univ Moscow Power Engn Inst Moscow 111250 Russia

We consider the problem of detecting spontaneous changes in the characteristics of a time series (a time series breakdown), when the breakdown manifests itself in the form of a stepwise change in the value of the location parameter (expectation or median) of the probability distribution function of the controlled process. It is proposed to solve this problem in real time applying a sequential nonparametric detection algorithm based on using the random walk theory mechanism. By computer simulation we investigate the probabilistic characteristics of the proposed algorithm and its efficiency in comparison with the well-known CUSUM-algorithm of parametric type. A procedure for synthesizing a control algorithm with the specified properties is given. It emphasizes the prospects of using such an algorithm in monitoring systems for various purposes, usually created in conditions of shortage of a priori information about the properties of the controlled process.

关键词： time series breakdown detection of changes in location characteristics sequential nonparametric detection algorithm random walk mechanism probabilistic algorithm characteristic algorithm efficiency control procedure synthesis monitoring system

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Fast volume rendering and cutting for finite element model

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COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING 2003年第2期18卷 121-131页

作者： Yang, XS Gu, YX Li, YP Guan, ZQ Tsing Hua Univ Dept Comp Sci & Technol Beijing 100084 Peoples R China Dalian Univ Technol Dept Mech Engn State Key Lab Struct Anal Ind Equipment Dalian 116024 Peoples R China

Based on the incremental slicing, a direct volume rendering algorithm for finite element meshes is proposed. To improve the algorithm efficiency, the element compensation method and sliced polygon forming method are presented. The image quality is improved greatly by the hybrid rendering of both the volume data and geometric surfaces. We also integrate a volume cutting method with arbitrary convex polyhedron into the volume rendering pipeline. This offers the user more flexibility to explore the data distribution inside structures.

关键词： data distribution Rendering self-harm algorithm efficiency Convex polyhedron Volume Image quality finite element model

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Solving long time-horizon dynamic optimal power flow of large-scale power grids with direct solution method

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IET GENERATION TRANSMISSION & DISTRIBUTION 2014年第5期8卷 895-906页

作者： Qin, Zhijun Hou, Yunhe Lu, En Luo, Cheng Cheng, Shijie Univ Hong Kong Dept Elect & Elect Engn Hong Kong Hong Kong Peoples R China S China Univ Technol Sch Elect Power Guangzhou Guangdong Peoples R China Midwest Independent Transmission Syst Operator In Dept Forward Operat Carmel IN USA Huazhong Univ Sci & Technol State Key Lab Adv Elect Engn & Technol Wuhan 430074 Peoples R China

Dynamic optimal power flow (DOPF) is an extension of optimal power flow for the optimal generation dispatch in a given time-horizon. The dynamic constraints bring tremendous numerical difficulties in solving this model. With particular attention to handle dynamic constraints, an efficient method has been presented for directly solving the large-scale DOPF Karush-Kuhn-Tucker (KKT) system arising from the primal-dual interior point method. First, the reduced KKT system is derived, showing that dynamic constraints lead to non-zeros in off-diagonal parts in the coefficient of KKT system. Then, the efficiency of the algorithm is improved by two measures: (i) to utilise the Cholesky factorisation algorithm, a constant diagonal perturbation is introduced in the positive-indefinite KKT coefficient and (ii) efficient reordering algorithms are identified and integrated in the sparse direct solver to improve the efficiency. Case studies on the IEEE 118-bus system over 24-96 time intervals are presented. These case studies show that the proposed method has a significant speed-up than decomposed interior point methods. The proposed method has also been successfully applied in Chinese realistic large-scale power grids. Two realistic case studies are reported. Both realistic cases have over 100 000 decision variables.

关键词： Direct Method Power flow Power grids optimal load flow kamikihi-to Case studies algorithm efficiency

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An efficient finite element solution using a large pre-solved regular element

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ACTA MECHANICA 2016年第5期227卷 1331-1349页

作者： Shojaei, I. Kaveh, A. Rahami, H. Univ Kentucky Dept Biomed Engn Lexington KY 40506 USA Iran Univ Sci & Technol Ctr Excellence Fundamental Studies Struct Engn Tehran Iran Univ Tehran Coll Engn Sch Engn Sci Tehran Iran

In this paper a finite element algorithm is presented using a large pre-solved hyper element. Utilizing the largest rectangle/cuboid inside an arbitrary domain, a large hyper element is developed that is solved using graph product rules. This pre-solved hyper element is efficiently inserted into the finite element formulation of partial differential equations (PDE) and engineering problems to reduce the computational complexity and execution time of the solution. A general solution of the large pre-solved element for a uniform mesh of triangular and rectangular elements is formulated for second-order PDEs. The efficiency of the algorithm depends on the relative size of the large element and the domain;however, the method remains as efficient as a classic method for even relatively small sizes. The application of the method is demonstrated using different examples.

关键词： Domain rectangular element SOLUTIONS(GENERAL) application methods FINITE ELEMENT complexity classes Triangular execution time algorithm efficiency

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Conceptual comparative study between efficient collision-handling algorithms used for Molecular Dynamics (MD) and Discrete Particle Model (DPM)

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POWDER TECHNOLOGY 2010年第3期198卷 435-438页

作者： Wu, C. L. Berrouk, A. S. Petr Inst Dept Chem Engn Abu Dhabi U Arab Emirates Guangdong Ocean Univ Coll Engn Zhanjiang 524088 Peoples R China

It is deemed substantial that understanding the conceptual differences between the hard-sphere Discrete Particle Model (DPM) and the event-driven Molecular Dynamics (MD) regarding the collision-event handling will help the design of new algorithms to increase the efficiency of collision-handling operations for DPM. The latter has gone largely unrecognized by most of the DPM-based numerical works on fluidization systems. We elaborated these differences and conceptually compared the only two O(1) time complexity algorithms developed for MD and DPM. It was shown that the hash-table strategy that takes into account the main features of fluidization systems increased considerably the efficiency of collision-handling algorithm for DPM. (C) 2009 Elsevier B.V. All rights reserved.

关键词： Particle Fluidization Collision algorithm efficiency Discrete particle modeling Molecular dynamics

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Generalized radial-return mapping algorithm for anisotropic von Mises plasticity framed in material eigenspace

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INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING 2018年第3期116卷 202-222页

作者： Versino, Daniele Bennett, Kane C. Los Alamos Natl Lab Theoret Div T-3 Los Alamos NM 87545 USA

A computationally efficient integration algorithm for anisotropic plasticity is proposed, which is identified as a generalization of the radial-return mapping algorithm to anisotropy. The algorithm is based upon formulation within the eigenspace of a material anisotropy tensor associated with anisotropic quadratic von Mises (J(2)) plasticity (also called Hill plasticity), for which it is shown to ensure that the flow rule remains associative, ie, the normality condition is satisfied. Extension of the algorithm to include anisotropic elasticity (anisotropic elastoplasticity) is further provided, made possible by the identification of a certain fourth-order material tensor dependent on both the elastic and plastic anisotropy. The derivation of the fully elastoplastically anisotropic algorithm involves further complexity, but the resulting algorithm is shown to closely resemble the purely plastically anisotropic one once the appropriate eigenspace is identified. The proposed generalized radial-return algorithm is compared to a classical closest-point projection algorithm, for which it is shown to provide considerable advantage in computational cost. The efficiency, accuracy, and robustness of the algorithm are demonstrated through various illustrative test cases and in the finite element simulation of Taylor impact tests on tantalum.

关键词： algorithm efficiency anisotropy elastoplasticity finite element method return mapping von Mises

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Application of the method of incomplete cross approximation to a nonstationary problem of vortex rings dynamics

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RUSSIAN JOURNAL OF NUMERICAL ANALYSIS AND MATHEMATICAL MODELLING 2012年第3期27卷 303-320页

作者： Stavtsev, S. L. Inst Numer Math Moscow 119333 Russia

An application of the method of incomplete cross approximation for solving a problem of vortex ring dynamics is described in the paper. A formulation of the problem and its solver based on the method of discrete vortices are presented. An adaptation of the incomplete cross approximation algorithm for the solution of nonstationary problems essentially improves computations in the problem described in this paper. A series of techniques improving the convergence is presented. The efficiency of the algorithms is confirmed by the results of numerical experiments.

关键词： Solvers dynamics Problem Formulation approximation transversality application methods vortex state (superconductivity) algorithm efficiency

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PAINTER: a spatiospectral image reconstruction algorithm for optical interferometry

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 2014年第11期31卷 2334-2345页

作者： Schutz, Antony Ferrari, Andre Mary, David Soulez, Ferreol Thiebaut, Eric Vannier, Martin Univ Nice Sophia Antipolis Lab JL Lagrange CNRS Observ Cote Azur F-06108 Nice 02 France Univ Lyon F-69003 Lyon France Univ Lyon 1 Observ Lyon F-69230 St Genis Laval France Ecole Normale Super Lyon CNRS UMR 5574 Ctr Rech Astrophys Lyon F-69007 Lyon France

Astronomical optical interferometers sample the Fourier transform of the intensity distribution of a source at the observation wavelength. Because of rapid perturbations caused by atmospheric turbulence, the phases of the complex Fourier samples (visibilities) cannot be directly exploited. Consequently, specific image reconstruction methods have been devised in the last few decades. Modern polychromatic optical interferometric instruments are now paving the way to multiwavelength imaging. This paper is devoted to the derivation of a spatiospectral (3D) image reconstruction algorithm, coined Polychromatic opticAl INTErferometric Reconstruction software (PAINTER). The algorithm relies on an iterative process, which alternates estimation of polychromatic images and complex visibilities. The complex visibilities are not only estimated from squared moduli and closure phases, but also differential phases, which helps to better constrain the polychromatic reconstruction. Simulations on synthetic data illustrate the efficiency of the algorithm and, in particular, the relevance of injecting a differential phases model in the reconstruction. (C) 2014 Optical Society of America

关键词： derivation differential phase Iterative Process Optical Interferometers atmospheric turbulence Three-Dimensional Images intensity distribution Phase synthetic data Fourier Transform algorithm efficiency Reconstruction algorithm

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