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An improvement in stability of delay difference systems

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chinese Science Bulletin 1998年第7期43卷 544-547页

作者： zhang Shunian Department of applied mathematics, shanghai jiaotong university, shanghai 200240, c.ina Department of applied mathematics Shanghai Jiaotong University Shanghai China

A new result on the stability of delay difference equations is established, in which a kind of weighted norm for x is adopted in order to estimate the upper bound of Liapunov functional.

关键词： delay difference systems uniform asymptotic stability in terms of two measures Liapunov functionals.

Almost periodic solutions of difference systems

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chinese Science Bulletin 1998年第24期43卷 2041-2046页

作者： zhang Shunian Department of applied mathematics, shanghai jiaotong university, shanghai 200240, c.ina Department of applied mathematics Shanghai Jiaotong University Shanghai China

For linear difference systems, a rather general result on the existence of almost periodic solutions is established, which also gives the explicit expression of the almost periodic solution in terms of the coefficient matrix and the nonhomogeneous term. The obtained result confirms not only the existence, but also the uniqueness as well as the uniform asymptotic stability of the almost periodic solution. As an application, a criterion on the existence of almost periodic solutions of the second order difference equations is derived.

关键词： difference systems mean values of almost periodic sequences almost periodic solutions existence uniqueness uniform asymptotic stability

ON UNIFORM ASYMPTOTIc STABILITY OF INFINITE DELAY DIFFERENcE EQUATIONS

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chinese Annals of mathematics,Series B 2001年第4期22卷 495-502页

作者： zhang SHUNIAN Department of applied mathematics, shanghai jiaotong university shanghai 200030, c.ina. E-mail: snzhang@*** Department of applied mathematics Shanghai Jiaotong University Shanghai 200030 China

For the infinite delay difference equations of the general form, two new uniform asymptotic stability criteria are established in terms of the discrete Liapunov functionals.

关键词： Infinite delay difference equations Uniform asymptotic stability g-uniform asymptotic stability Discrete Liapunov functionals

On the Limit cycles of Quadratic Differential Systems

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Acta Mathematica Sinica,English Series 2002年第4期18卷 803-816页

作者： Xiang zhang Department of mathematics, shanghai jiaotong university, shanghai 200030, P. R. c.ina Department of mathematics Shanghai Jiaotong University Shanghai 200030 P. R. China

In this paper we give the necessary and sufficient conditions for all finite critical points of quadratic differential systems to be weak foci, and solve an open problem proposed by Yanqian Ye.

关键词： Quadratic differential system Limit cycle Ergodicity.

Simulation of nuclei morphologies for binary alloy

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Science c.ina mathematics 2010年第11期53卷 2927-2936页

作者： LI DaMing1, & zhang PingWen2 1Department of mathematics, shanghai jiaotong university, shanghai 200240, c.ina 2Key Lab of mathematics and applied mathematics, center for applied Physics and Technology and School of Mathematical Sciences, Peking university, Beijing 100871, c.ina 1. Department of mathematics Shanghai Jiaotong University Shanghai 200240 China2. Key Lab of Mathematics and Applied Mathematics Center for Applied Physics and Technology and School of Mathematical Sciences Peking University Beijing 100871 China

We study the critical nuclei morphologies of a binary alloy by the string method. The dynamic equation of the string, connecting the metastable phase (liquid) and stable phase (solid), is governed by Helmholtz free energy for the binary alloy system at a given temperature. The stationary string through the critical nucleus (saddle point) is obtained if the relaxation time of the string is su?ciently large. The critical nucleus radius and energy barrier to nucleation of a pure alloy with isotropic interface energy in two and three dimensions are calculated, which are consistent with the classical nucleation theory. The critical nuclei morphologies are sensitive to the anisotropy strength of interface energy and interface thickness of alloy in two and three dimensions. The critical nucleus and energy barrier to nucleation become smaller if the anisotropy strength of the interface energy is increased, which means that it is much easier to form a stable nucleus if the anisotropy of the interface energy is considered.

关键词： nucleation crystal morphology string method

SEMI-DEFINITE RELAXATION ALGORITHM FOR SINGLE MAcHINE ScHEDULING WITH cONTROLLABLE PROcESSING TIMES

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chinese Annals of mathematics,Series B 2005年第1期26卷 153-158页

作者： cHENFENG zhangLIANSHENG Departmentofmathematics ShanghaiUniversityShanghai200436China／／DepartmentofIndustrialEngineeringandManagementShanghaiJiaotongUniversityShanghai200030China. Departmentofmathematics ShanghaiUniversityShanghai200436China

The authors present a semi-definite relaxation algorithm for the scheduling problem with controllable times on a single machine. Their approach shows how to relate this problem with the maximum vertex-cover problem with kernel constraints (MKVc).The established relationship enables to transfer the approximate solutions of MKVcinto the approximate solutions for the scheduling problem. Then, they show how to obtain an integer approximate solution for MKVc based on the semi-definite relaxation and randomized rounding technique.

关键词： Scheduling with controllable times Semi-definite programming Approximation algorithm

comparison of coal-Based Dimethyl Ether and Diesel as Vehicle Fuels from Well to Wheel in c.ina

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Journal of shanghai jiaotong university(Science) 2009年第2期14卷 210-214页

作者：张亮黄震 School of Mechanical Engineering Shanghai Jiaotong University

With life cycle assessment(LcA) methodology,a life cycle model of coal-based vehicle fuels(cBVFs) including coal-based dimethyl ether(cBDME) and coal-based diesel(cBD) is *** primary energy consumption(PEc) and global warming potential(GWP) from well to wheel including feedstock extraction,fuel production,fuel consumption in vehicle and energy transportation are calculated and *** show that the life cycle PEc and GWP of cBD pathway are 1.17 and 1.34 times as cBDME *** on the above results,cBDME will become a choice with great potential to replace conventional petroleum-based diesel (cPBD) in c.ina.

关键词： coal-based vehicle fuel (cBVF) life cycle assessment (LcA) primary energy consumption (PEc) global warming potential (GWP)

FEEDBAcK LINEARIZATION cONTROL FOR ELEcTRONIcALLY cONTROLLABLE cLUTcH OF VEHIcLE

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chinese Journal of Mechanical Engineering 1999年第4期12卷 303-311页

作者： chen Li zhang Jianwu Huang Weigang shanghai jiaotong university Gao chunming shanghai clutch Factory shanghai jiaotong Univ China

An investigation is made to the friction chutch engagement control of automotive AMT systems based on a nonlinear dynamic model with double inputs. According to friction torque transmission characteristics during clutch engagement, an equivalent, fully controllable and linearized model and the feedback linearization control are derived from the original system with nonlinearities via homomorphic transforms. By the resulting mathematical modeling, computer simulations are made both for the original nonlinear and feedback linearized systems with incorporation of ordinary PID controllers to follow ideal vehicle dynamic responses. It has been shown by comparison between the two sets of numerical results that the feedback linearization control designed for the nonlinear system is of fine accuracy and robustness in model tracking behaviors of clutch engagements.

关键词： Automated clutch Nonlinear system dynamics Feedback linearization

MAGNETIc FIELD ANALYSIS OF ELEcTROMAGNETIc VALVE TAKING HYSTERESIS INTO AccOUNT

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chinese Journal of Mechanical Engineering 2003年第3期16卷 245-247页

作者： zhang ShengchangZhong TingxiuXu YangzengShi GuanglinSchool of Mechanical Engineering,shanghai jiaotong university,shanghai 200030, c.ina School of Mechanical Engineering Shanghai Jiaotong University 上海 200030

Predicting and optimizing of the high-speed solenoid on/off valve behaviorrequires an accurate model of the hysteresis loop of the magnetic material used A ferromagnetichysteresis model and a novel algorithm based on fixed-point technique to optimize theelectromagnetic model are introduced By utilizing a modified vector Preisach model of magnetichysteresis and the global genetic optimization algorithm based on partial mapping cross method, theB-H relation loops are identified accurately.

关键词： High-speed electromagnetic on/off valve Preisach model Genetic algorithm