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90°弯管的纤维缠绕线型设计 被引量:12
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作者 韩振宇 富宏亚 +1 位作者 王永章 付云忠 《玻璃钢/复合材料》 CAS CSCD 2004年第5期31-32,35,共3页
针对 90°弯管的纤维缠绕问题 ,应用微分几何曲面理论分别得到了圆环面的测地线和圆柱面的非测地线表达式 ,生成了纤维路径 ,并且通过在圆柱段端头加入停留 ,解决了弯管缠绕时的布满问题 ,为 90°弯管的纤维缠绕奠定了理论基础。
关键词 90°弯管 纤维缠绕 线型设计 玻璃纤维增强塑料管 线型仿真 布满分析
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Numerical investigation on the aerodynamic drag reduction based on bottom deflectors and streamlined bogies of a high-speed train
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作者 JIANG Chen LONG jn-lan +2 位作者 LI Yan-ong GAO Guang-jun FRANKLIN Eze 《Journal of Central South University》 SCIE EI CAS CSCD 2024年第9期3312-3328,共17页
The complex structure of the bottom of a high-speed train is an important source of train aerodynamic drag.Thus,improving the bottom structure is of great significance to reduce the aerodynamic drag of the train.In th... The complex structure of the bottom of a high-speed train is an important source of train aerodynamic drag.Thus,improving the bottom structure is of great significance to reduce the aerodynamic drag of the train.In this study,computational fluid dynamics(CFD)based on three-dimensional steady incompressible Reynolds-average Naiver-Stokes(RANS)equations and Realizable k-ε turbulence model were utilized for numerical simulations.Inspired by the concept of streamlined design and the idea of bottom flow field control,this study iteratively designed the bogies in a streamlined shape and combined them with the bottom deflectors to investigate the joint drag reduction mechanism.Three models,i.e.,single-bogie model,simplified train model,and eight-car high-speed train model,were created and their aerodynamic characteristics were analyzed.The results show that the single-bogie model with streamlined design shows a noticeable drag reduction,whose power bogie and trailer bogie experience 13.92%and 7.63%drag reduction,respectively.The range of positive pressure area on the bogie is reduced.The aerodynamic drag can be further reduced to 15.01%by installing both the streamlined bogie and the deflector on the simplified train model.When the streamlined bogies and deflectors are used on the eight-car model together,the total drag reduction rate reaches 2.90%.Therefore,the proposed aerodynamic kit for the high-speed train bottom is capable to improve the flow structure around the bogie regions,reduce the bottom flow velocity,and narrow the scope of the train’s influence on the surrounding environment,achieving the appreciable reduction of aerodynamic drag.This paper can provide a new idea for the drag reduction of high-speed trains. 展开更多
关键词 high-speed train numerical simulation drag reduction DEFLECTOR streamlined design
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Modeling and Simulation of the Characteristics of Pneumatic Cushion Cylinders 被引量:6
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作者 江泽民 张百海 +2 位作者 王涛 彭光正 王海涛 《Journal of Beijing Institute of Technology》 EI CAS 2002年第2期129-132,共4页
The analysis of the characteristics of the cushion process of the pneumatic cushion cylinder is presented, and the nonlinear model of pneumatic cushion cylinders is built in the form of nonlinear differential equation... The analysis of the characteristics of the cushion process of the pneumatic cushion cylinder is presented, and the nonlinear model of pneumatic cushion cylinders is built in the form of nonlinear differential equations. Besides, through the simulation of the pressure in the cushion chamber, the characteristics of the pneumatic cushion cylinder are obtained, which helps to understand the performance of the pneumatic cushion cylinder and improve or design the better cushion structure. 展开更多
关键词 pneumatic cushion cylinder nonlinear model SIMULATION
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A method of elimination of undesired resonant points of microstrip antenna by cutting U-shaped slot on the ground
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作者 TENG Fei CHENG Xiu-yang 《Journal of Measurement Science and Instrumentation》 CAS 2014年第2期80-82,共3页
A method is proposed to eliminate undesired resonant points of a dual-layer circular polarization microstrip antenna, the frequency of which is 2.42 GHz. The simulation results show that there are two undesired resona... A method is proposed to eliminate undesired resonant points of a dual-layer circular polarization microstrip antenna, the frequency of which is 2.42 GHz. The simulation results show that there are two undesired resonant points, the frequencies of which are both greater than the resonant frequency. One is around 4.4 GHz, while the other is around 5.8 GHz. As they would disturb the proper functioning of the antenna, the paper will eliminate the undesired resonant points by cutting U-shaped slots on the ground, Size of the slot is half of the wavelength of corresponding frequency point if slot is cut on the patch, while it is a quarter of the wavelength if there is a opening port on the slot. The simulation results show that it's effective to eliminate the undesired resonant points in this way. 展开更多
关键词 resonant points microstrip antenna U-shaped slot simulation
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Computer simulation of active suspension based on the full-vehicle model 被引量:2
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作者 李军 CHEN Shanguo 《Journal of Chongqing University》 CAS 2002年第2期24-27,共4页
Abstract: The current method to solve the problem of active suspension control for a vehicle is often dealt with a quarter-car or half-car model. But it is not enough to use this kind of model for practical applicatio... Abstract: The current method to solve the problem of active suspension control for a vehicle is often dealt with a quarter-car or half-car model. But it is not enough to use this kind of model for practical applications. In this paper, based on considering the influence of factors such as, seat and passengers, a MDOF(multi-degree-of-freedom) model describing the vehicle motion is set up. The MODF model, which is 8DOF of four independent suspensions and four wheel tracks, is more applicable by comparison of its analysis result with some conventional vehicle models. Therefore, it is more suitable to use the 8DOF full-car model than a conventional 4DOF half-car model in the active control design for car vibration. Based on the derived 8DOF model, a controller is designed by using LQ (linear quadratic ) control theory, and the appropriate control scheme is selected by testing various performance indexes. Computer simulation is carried out for a passenger car running on a road with step disturbance and random road disturbance expressed by Power Spectral Density (PSD). Vibrations corresponding to ride comfort are derived under the foregoing road disturbances. The response results for uncontrolled and controlled system are compared. The response of vehicle vibration is greatly suppressed and quickly damped, which testifies the effect of the active suspension. The results achieved for various controllers are compared to investigate the influence of different control schemes on the control effect. 展开更多
关键词 active suspension LQ control 8DOF model
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An optimal filter based MPC for systems with arbitrary disturbances 被引量:1
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作者 Haokun Wang Zuhua Xu +1 位作者 Jun Zhao Aipeng Jiang 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2017年第5期632-640,共9页
In this study, a linear model predictive control(MPC) approach with optimal filters is proposed for handling unmeasured disturbances with arbitrary statistics. Two types of optimal filters are introduced into the fram... In this study, a linear model predictive control(MPC) approach with optimal filters is proposed for handling unmeasured disturbances with arbitrary statistics. Two types of optimal filters are introduced into the framework of MPC to relax the assumption of integrated white noise model in existing approaches. The introduced filters are globally optimal for linear systems with unmeasured disturbances that have unknown statistics. This enables the proposed MPC to better handle disturbances without access to disturbance statistics. As a result, the effort required for disturbance modeling can be alleviated. The proposed MPC can achieve offset-free control in the presence of asymptotically constant unmeasured disturbances. Simulation results demonstrate that the proposed approach can provide an improved disturbance ?rejection performance over conventional approaches when applied to the control of systems with unmeasured disturbances that have arbitrary statistics. 展开更多
关键词 Model predictive control Optimal filter Disturbance modeling Disturbance statistics Unmeasured disturbances
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AUV Modeling and Motion Control Strategy Design 被引量:1
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作者 王芳 万磊 +1 位作者 苏玉民 徐玉如 《Journal of Marine Science and Application》 2010年第4期379-385,共7页
To provide a suitable model for AUV simulation and control purposes, a general nonlinear dynamic model including a novel thruster hydrodynamics model was derived. Based on the modeling method, the "AUV-XX" s... To provide a suitable model for AUV simulation and control purposes, a general nonlinear dynamic model including a novel thruster hydrodynamics model was derived. Based on the modeling method, the "AUV-XX" simulation platform was established to carry out fundamental tests on its motion characteristics, stability, and controllability. A motion control strategy consisting of both position and speed control in a horizontal plane was designed for different task assignments of underwater vehicles. Combined control of heave and pitch was adopted to compensate for the reduction of vertical tunnel thrusters when the vehicle is moving at a high speed. An improved S-surface controller based on the capacitor plate model was developed with flexible gain selections made possible by different forms of restricting the error and changing the rate of the error. Simulation results show that the derived general mathematical model together with simulation platform can provide a test bed for fundamental tests of motion control. Additionally, the capacitor plate model S-surface control shows a good performance in guiding the vehicle to achieve the desired position and speed with sufficient accuracy. 展开更多
关键词 AUV general dynamic model hydrodynamics modeling simulation platform motion control
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Multi-domain modeling and simulation of proportional solenoid valve 被引量:3
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作者 刘艳芳 戴振坤 +1 位作者 徐向阳 田亮 《Journal of Central South University》 SCIE EI CAS 2011年第5期1589-1594,共6页
A multi-domain nonlinear dynamic model of a proportional solenoid valve was presented.The electro-magnetic,mechanical and fluid subsystems of the valve were investigated,including their interactions.Governing equation... A multi-domain nonlinear dynamic model of a proportional solenoid valve was presented.The electro-magnetic,mechanical and fluid subsystems of the valve were investigated,including their interactions.Governing equations of the valve were derived in the form of nonlinear state equations.By comparing the simulated and measured data,the simulation model is validated with a deviation less than 15%,which can be used for the structural design and control algorithm optimization of proportional solenoid valves. 展开更多
关键词 fluid mechanics proportional solenoid valve dynamic characteristic multi-domain modeling SIMULATION
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Fully Coupled Time-Domain Simulation of Dynamic Positioning Semi-Submersible Platform Using Dynamic Surface Control 被引量:1
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作者 LIANG Haizhi LI Luyu OU Jinping 《Journal of Ocean University of China》 SCIE CAS 2014年第3期407-414,共8页
A fully coupled 6-degree-of-freedom nonlinear dynamic model is presented to analyze the dynamic response of a semi-submersible platform which is equipped with the dynamic positioning(DP) system. In the control force d... A fully coupled 6-degree-of-freedom nonlinear dynamic model is presented to analyze the dynamic response of a semi-submersible platform which is equipped with the dynamic positioning(DP) system. In the control force design, a dynamic model of reference linear drift frequency in the horizontal plane is introduced. The dynamic surface control(DSC) is used to design a control strategy for the DP. Compared with the traditional back-stepping methods, the dynamic surface control combined with radial basis function(RBF) neural networks(NNs) can avoid differentiating intermediate variables repeatedly in every design step due to the introduction of a first order filter. Low frequency motions obtained from total motions by a low pass filter are chosen to be the inputs for the RBF NNs which are used to approximate the low frequency wave force. Considering the propellers' wear and tear, the effect of filtering frequencies for the control force is discussed. Based on power consumptions and positioning requirements, the NN centers are determined. Moreover, the RBF NNs used to approximate the total wave force are built to monitor the disturbances. With the DP assistance, the results of fully coupled dynamic response simulations are given to illustrate the effectiveness of the proposed control strategy. 展开更多
关键词 dynamic positioning system coupled analysis dynamic surface control RBF NNs adaptive control
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Cardinal temperatures and required biological days from sowing to emergence of three millet species (common, foxtail, pearl millet)
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作者 Morteza Eshraghi Nejad Behnam Kamkar Atfshin Soltani 《Journal of Agricultural Science and Technology》 2009年第12期36-43,共8页
The modeling of germination and seedling emergence is required for the construction of a simulation model of three species of millet (panicum miliaceum, pennisetum galucum and setaria italica). This study provides t... The modeling of germination and seedling emergence is required for the construction of a simulation model of three species of millet (panicum miliaceum, pennisetum galucum and setaria italica). This study provides the necessary temperature parameters to model these processes. For this purpose, different non-linear regression models including fiat, logistic, quadratic, sigmoidal, dent-like, segmented, beta and curvilinear were used. Root Mean Square of Errors, coefficient of determination and regression coefficients of predicted values versus observed were used to find the appropriate model. Investigating regression coefficients indicated that dent-like model has the least RMSE and a coefficient (RMSE=0.000009, a=0.0006) and the biggest R2 and b coefficient (R2=0.96, b=0.98) in common millet. These coefficients were (RMSE=0.01, a=0.005) and (R2=0.94, b=0.97), and (RMSE=0.004, a=0.05) and (R2=0.99, b=0.99), for beta in foxtail and pearl millet, respectively. According to these coefficients, dent-like, was chosen as the best model to describe the response of common millet germination to temperature (Tb=7~C and Tc=49.50℃). Also beta, was chosen for foxtail millet (Tb=7℃, Tc=49.50℃). Beta, was chosen as the best model for pearl millet (Tb=6.5 ℃ and To=4 ℃ ). These parameters can be used in millet simulation models to predict sowing to emergence duration based on a thermal time concept. Also, required biological days from sowing to emergence using these models varied from 3.57, 4.29 and 5.54, for common millet, foxtail millet and pearl millet, respectively. 展开更多
关键词 cardinal temperature germination rate nonlinearfitting MILLET
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Simulation analysis for O-cell test of pile and the interaction of upper pile and lower pile
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作者 郑英杰 张克绪 张尔其 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2009年第4期541-547,共7页
In this paper,the soil-pile system of O-cell test of pile is simplified as an axi-symmetric problem.By using aggregation of quadrilateral isoparametric elements to simulate pile and soil,setting Goodman's elements... In this paper,the soil-pile system of O-cell test of pile is simplified as an axi-symmetric problem.By using aggregation of quadrilateral isoparametric elements to simulate pile and soil,setting Goodman's elements between pile and soils,a method of numerical simulation analysis on O-cell test of pile is presented with the consideration of nonlinear mechanical behavior of soils and pile-soil interface.The method is applied to the analysis of a case of O-cell test of pile.The load-displacement curves and axial force curves of upper pile and lower pile obtained from the O-cell test of pile are fitted,and parameters of the mechanical model of soils and interface are determined.Analysis results validate that the numerical simulation analysis method put forward in this paper is applicable.Furthermore,the interaction and influence of upper pile and lower pile in the O-cell test are also studied with the method.The result shows that if load box is located in a soil layer with fine mechanical behavior,the interaction of upper pile and lower pile in O-cell test can be ignored generally. 展开更多
关键词 O-cell test of pile simulation analysis nonlinear behavior p-s curve interaction
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Multi-objectives and Simulation Models for Develop Production Line in Automobiles Manufacturing System
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作者 Razman Bin Tahar Ali A. J Adham 《Chinese Business Review》 2011年第7期553-558,共6页
Automotive manufacturing is complex and includes the coordination of design in the manufacturing system. The manufacturing approaches over the past few years, disassembly have been a key issue, and it seems that simul... Automotive manufacturing is complex and includes the coordination of design in the manufacturing system. The manufacturing approaches over the past few years, disassembly have been a key issue, and it seems that simulation models are usually tailored to address a narrow set of industrial issues. This paper describes the development of the production line in the automobile manufacturing system through design, operation, and maintenance, based on multi-objectives of Algorithm and Simulation Model called MOA-SM. The both models are being developed at three different levels: the production line in the body and assembly shop, supply chain, and the production plan. The optimization tries to involve more objectives to solve the issues in manufacturing system. A solution that may optimize one performance measure may deteriorate since other performance solutions are difficult. The resulting algorithms are comparable to the simulation and multi-object in terms of success rate, assembly times, peak forces, moments, and have assembly times superior to those of a benchmark blind search algorithm. 展开更多
关键词 assembly line automotive manufacturing supply chain simulation model MULTI-OBJECTIVE production line
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Geometric design and simulation of tooth profile using elliptical segments as its line of action
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作者 王建 罗善明 +1 位作者 苏德瑜 常雪峰 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第6期2119-2126,共8页
A mathematical model of gear tooth profiles using the ellipse curve, whose curvature is convenient to control by changing the mathematical parameters as its line of action, was built based on the meshing theory. The e... A mathematical model of gear tooth profiles using the ellipse curve, whose curvature is convenient to control by changing the mathematical parameters as its line of action, was built based on the meshing theory. The equation of undercutting condition was derived from the model. A special epicycloidal tooth profile was also presented. An example gear drive with variation of the ellipse parameters was taken to illustrate the proposed method. The contact ratio of the gear drive designed by the proposed method was analyzed. A comparison of the property of the gear drive designed with the involute gear drive was also carried out. The results confirm that the proposed gear drive has higher contact ratio in comparison with the involute gear drive. 展开更多
关键词 gear transmission tooth profile elliptical segment epicycloidal contact ratio
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The mathematical model and simulation of the electrostatic suspension system in the vertical direction
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作者 Ku Shaoping Zhou Zude Hu Yefa 《Engineering Sciences》 EI 2008年第2期46-49,共4页
In order to research the vibration law of electrostatic suspension systems in the vertical direction, the mathematical model as a nonlinear differential equation is established. A series of simulation is carried out. ... In order to research the vibration law of electrostatic suspension systems in the vertical direction, the mathematical model as a nonlinear differential equation is established. A series of simulation is carried out. The results show that the solution of the differential equation is a periodic function. The amplitude becomes bigger with the original velocity increased. The period becomes smaller with the original velocity increasing. The numerical methods are presented to derive the amplitude and the frequency, and the results coincide with that of the simulation. The condition during which the simple harmonic vibration arises is pointed out. The expressions for the amplitude and the period of simple harmonic vibration are derived respectively, and the results are the same with that of the simulation. This study is helpful for researching the vibration characteristics of the electrostatic suspension system. The external disturb should be controlled to lower the amplitude and the frequency of the vibration. 展开更多
关键词 electrostatic suspension mathematical model SIMULATION
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Simulation of the spin-boson model with superconducting phase qubit coupled to a transmission line 被引量:6
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作者 YU LongBao TONG NingHua +2 位作者 XUE ZhengYuan WANG ZiDan ZHU ShiLiang 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2012年第9期1557-1561,共5页
Based on the rapid experimental developments of circuit QED,we propose a feasible scheme to simulate the spin-boson model with superconducting circuits,which can be used to detect quantum Kosterlitz-Thouless(KT) phase... Based on the rapid experimental developments of circuit QED,we propose a feasible scheme to simulate the spin-boson model with superconducting circuits,which can be used to detect quantum Kosterlitz-Thouless(KT) phase transition.We design the spinboson model by using a superconducting phase qubit coupled to a semi-infinite transmission line,which is regarded as a bosonic reservoir with a continuum spectrum.By tuning the bias current or the coupling capacitance,the quantum KT transition can be directly detected through tomography measurement on the states of the phase qubit.We also estimate the experimental parameters using the numerical renormalization group method. 展开更多
关键词 spin-boson model superconducting qubit quantum phase transition numerical renormalization group method
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EMPIRICAL LIKELIHOOD CONFIDENCE REGION FOR PARAMETERS IN LINEAR ERRORS-IN-VARIABLES MODELS WITH MISSING DATA 被引量:3
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作者 Juan ZHANG Hengjian CUI 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2011年第3期540-553,共14页
The multivariate linear errors-in-variables model when the regressors are missing at random in the sense of Rubin (1976) is considered in this paper. A constrained empirical likelihood confidence region for a parame... The multivariate linear errors-in-variables model when the regressors are missing at random in the sense of Rubin (1976) is considered in this paper. A constrained empirical likelihood confidence region for a parameter β0 in this model is proposed, which is constructed by combining the score function corresponding to the weighted squared orthogonal distance based on inverse probability with a constrained region of β0. It is shown that the empirical log-likelihood ratio at the true parameter converges to the standard chi-square distribution. Simulations show that the coverage rate of the proposed confidence region is closer to the nominal level and the length of confidence interval is narrower than those of the normal approximation of inverse probability weighted adjusted least square estimator in most cases. A real example is studied and the result supports the theory and simulation's conclusion. 展开更多
关键词 Confidence region coverage rate empirical likelihood ratio multivariate linear errors-in- variables model weighted adjusted LS estimation.
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Large Eddy Simulation of Swirling Jet in a Bluff-Body Burner
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作者 Yohei FUJIMOTO Yuzo INOKUCHI Nobuhiko YAMASAKI 《Journal of Thermal Science》 SCIE EI CAS CSCD 2005年第1期28-33,共6页
The large eddy simulation (LES) is applied to an unconfined swirling flow of an air surrounding a bluff-body having a central jet of air, and the complicated flowfield that involves the recirculation and vortex breakd... The large eddy simulation (LES) is applied to an unconfined swirling flow of an air surrounding a bluff-body having a central jet of air, and the complicated flowfield that involves the recirculation and vortex breakdown is investigated. The Smagorinsky model is used as the sub-grid scale model. The results of the present numerical simulation are compared with the experimental data of the mean and stochastic root mean square (RMS) variations of two velocity components. Although the inflow conditions are specified in a simple manner, the obtained numerical results are in reasonable agreement with the experiments, except for a part of RMS variation values near downstream of the bluff body. The present numerical calculations can successfully reproduce the two characteristics of the flow, i.e., an upstream recirculation zone established just downstream of the burner plane and the additional recirculation zone established at the more downstream location. 展开更多
关键词 large eddy simulation SWIRL BLUFF-BODY recirculation.
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Updating preconditioner for iterative method in time domain simulation of power systems 被引量:3
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作者 WANG Ke XUE Wei +2 位作者 LIN HaiXiang XU ShiMing ZHENG WeiMin 《Science China(Technological Sciences)》 SCIE EI CAS 2011年第4期1024-1034,共11页
The numerical solution of the differential-algebraic equations(DAEs) involved in time domain simulation(TDS) of power systems requires the solution of a sequence of large scale and sparse linear systems.The use of ite... The numerical solution of the differential-algebraic equations(DAEs) involved in time domain simulation(TDS) of power systems requires the solution of a sequence of large scale and sparse linear systems.The use of iterative methods such as the Krylov subspace method is imperative for the solution of these large and sparse linear systems.The motivation of the present work is to develop a new algorithm to efficiently precondition the whole sequence of linear systems involved in TDS.As an improvement of dishonest preconditioner(DP) strategy,updating preconditioner strategy(UP) is introduced to the field of TDS for the first time.The idea of updating preconditioner strategy is based on the fact that the matrices in sequence of the linearized systems are continuous and there is only a slight difference between two consecutive matrices.In order to make the linear system sequence in TDS suitable for UP strategy,a matrix transformation is applied to form a new linear sequence with a good shape for preconditioner updating.The algorithm proposed in this paper has been tested with 4 cases from real-life power systems in China.Results show that the proposed UP algorithm efficiently preconditions the sequence of linear systems and reduces 9%-61% the iteration count of the GMRES when compared with the DP method in all test cases.Numerical experiments also show the effectiveness of UP when combined with simple preconditioner reconstruction strategies. 展开更多
关键词 differential-algebraic equations GMRES updating preconditioner power system simulation
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Modeling and simulation of non-linear dynamic process of the induction motor system with fluctuating potential loads 被引量:13
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作者 LUO Wei WANG Bo +1 位作者 ZHAO HaiSen LUO YingLi 《Science China(Technological Sciences)》 SCIE EI CAS 2014年第9期1729-1737,共9页
The induction motor system with fluctuating potential loads is a non-linear complex electro-mechanical system.With beam pumping motors as an example,this paper proposes a multiple factor non-linear mathematical model ... The induction motor system with fluctuating potential loads is a non-linear complex electro-mechanical system.With beam pumping motors as an example,this paper proposes a multiple factor non-linear mathematical model to study the operating performance of the induction motor system.This model consists of non-linear time varying electromagnetic field equations,mechanical wave equations of sucker rods and non-linear coupling equation of reducer and four-bar linkage.The equations are numerically solved by combining time-step finite element method(TS-FEM),finite difference method(FDM),a linear dimension reduction method and the Newton-Raphson method.Simulation results,which are validated by experiments,reveal the influence of the fluctuating potential load on magnetic field distributions,stator and rotor currents,the input power and the power factor.The model and simulation results provide theoretical and technical supports for subsequent researches on model simplification and energy saving technologies. 展开更多
关键词 induction motors electromagnetic field equation wave equations TS-FEM finite difference method
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