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Some Equivalence Transform methods for Simulating Models in Control Systems

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Journal of Systems Engineering and Electronics 1993年第4期4卷 32-42页

作者： Degui, Liu Beijing Inst of Computer Application and Simulation Technology Beijing China

In this paper two classes of equivalence transform methods for solving ordinary differential equations are proposed. One class of method is the equivalence integral transform method for special differential algebraic problems. The advantage of this class of method is such that the amount of work calculating one integration with parameters becomes that of two interpolations, when the system of nonlinear equations is solved on the right hand side function. The other class of method is the equivalence substitution method for avoiding calculating derivative on the right hand side function. In order to avoid calculation derivatives, two equivalence substitution methods are proposed here. The application instances of some special effect of the equivalence substitution methods are given.

关键词： Algebra Calculations Computer simulation Control systems Differential equations Integration Interpolation Mathematical models Mathematical transformations Nonlinear equations numerical methods

RESEARCH ON MOTION CHARACTERISTICS OF GAS-SOLID JET FLOW

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Journal of Hydrodynamics 1999年第2期11卷 103-110页

作者： Lin, Jianzhong Ni, Limin Liu, Zhongqiu Zhejiang Univ Hangzhou China

Evolution of vortex structures in round jet was simulated with a three-dimensional discrete vortex filament method. The motion of the particles was described by a Lagrangian equation and the counteraction of particles on the flow was taken into account by using a modified velocity model. It is indicated that in two-phase jet flow the introduced particles restrain the crosswise dispersion of jet shear layer and mergence of vortex structures. With the increase of St number, the influence of flow on particles motion is decreased, but the counteraction of particles on the flow is increased. The difference of flow field obtained with two models, one-way coupling model and two-way coupling model, is greater than that of particles trajectories.

关键词： Flow of fluids Fluid structure interaction Jets numerical analysis numerical methods Particles (particulate matter) Turbulent flow Vortex flow

numerical STUDY OF TURBULENT JETS CONFINED BETWEEN TWO CONCENTRIC SPHERES

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Journal of Hydrodynamics 1994年第1期6卷 86-90页

作者： Zhang, Guanghua Tang, Gefeng Tsinghua Univ Beijing China

In this paper a numerical method for understanding the flow pattern and calculating the available torque in a single axis subsystem version of advanced inertial reference sphere was provided. The governing equations were parabolized in stream-wise direction. The SIMPLEC algorithm coupled with an algebraic second-moment closure of turbulence was applied to solving the equations. Computational results were compared with measurements.

关键词： Mathematical models numerical methods Torque Turbulent flow Viscous flow

Mode characteristics of hollow core Bragg fiber

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Chinese Optics Letters 2005年第3期3卷 132-135页

作者：季敏宁石志东郭强 Institute of Fiber Optics

Analytical expression to calculate propagation constant and mode field of the hollow core Bragg fiber is derived. numerical results are presented. It is shown that the fundamental mode of the hollow core Bragg fiber is circularly symmetric TE01 mode with no polarization degeneracy, while the higher order mode may be HE11, TM01, or TEo2 etc.. This property is different from conventional optical fiber that its fundamental mode is the linearly polarized HE11 mode and is polarization degeneracy.

关键词： Calculations Light polarization Light propagation numerical methods Optical fibers

Polarization effect in parametric amplifier

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Chinese Optics Letters 2005年第9期3卷 500-502页

作者：周俊鹤陈建平李新碗吴龟灵王义平 State Key Laboratory of Advanced Optical Communication Systems and Networks Shanghai Jiao Tong University Shanghai 200030

Polarization effect in parametric amplifiers is studied. Coupled equations are derived from the basic propagation equations and numerical solutions are given for both one-wavelength-pump and two-wavelengthpump systems. Several parametric amplifiers driven by pumps at one wavelength and two wavelengths are analyzed and the polarization independent parametric amplifier is proposed.

关键词： Nonlinear equations numerical methods Optical communication Polarization Pumps

New Explorations for Decision Trees

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Journal of Systems Engineering and Electronics 2001年第4期12卷 37-40页

作者：冯俊文 School of Economics and Management Nanjing University of Science and Technology Nanjing 210094 P. R. China

Traditionally, the decision tree method is defined and used for finding the optimal solution of a Bayesian decision problem. And it is difficult to use the decision tree method to find the sub-optimal solution, not to mention to rank alternatives. This paper discusses how to use the decision tree method for the alternative selecting and ranking. A practical case study is given to illustrate the applicability.

关键词： Decision making Decision theory numerical methods Optimization Problem solving

numerical SIMULATION OF A TWO-DIMENSIONAL SQUARE MOVING NEAR FREE SURFACE

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Journal of Hydrodynamics 2001年第1期13卷 54-57页

作者： Hong, F.W. Zhao, F. Zhou, L.D. China Ship Sci. Res. Cent. P. O. Box 116 Wuxi 214082 China

A body moving near the free surface is a focus in fluid dynamic research. Many numerical methods were developed for the simulation of the induced flow field. In this paper, a two-dimensional square moving near the free surface was simulated by the volume of fluid method (VOF). The flow field and drag exerted on the square were studied. The drag would increase due to the presence of the free surface. The iteration factor of the pressure interpolation of surface cells was modified, and through this modification the iteration became more stable. The capability of dealing with the large deformation of the free surface was raised.

关键词： Computational fluid dynamics Computer simulation Drag numerical methods

HAGEN POISEUILLE FLOW OF A GRANULAR MATERIAL IN A CYLINDER

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Journal of Hydrodynamics 2001年第2期13卷 91-95页

作者： Liu, M.J. Tao, M.D. Dept. of Mech. and Eng. Sci. Fudan Univ. Shanghai 200433 China

The equations of motion for rapid flow of a granular material were derived and their solutions representing flow driven by a body force along an infinitely-long cylinder were obtained by the numerical method.

关键词： Boundary conditions Cylinders (shapes) Equations of motion Flow of solids numerical methods

Inverse Design of Electron Lens

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Journal of Systems Engineering and Electronics 2001年第1期12卷 49-52页

作者： Tu Yan & Zhong Xuefei Electronics Research Institute, Southeast University, Nanjing 210096, P. R. China Electronics Research Institute Southeast University Nanjing 210096 P. R. China

The inverse design of electron lens is realized by two different methods in this paper. One is damped least square method and the other is the artificial neural network method. Their merits and defects are discussed according to our calculation results in the paper. In the condition of selecting the learning samples properly, the artificial neural network has obvious advantages in the inverse design of electron lens. It is an effective method to solve the inverse design problem in the electron optic system.

关键词： Electron optics Least squares approximations Neural networks numerical methods Optical design