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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, china 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

Quantitative result on stability for delay difference systems

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Chinese Science Bulletin 1997年第22期42卷 1858-1861页

作者： zhang shuniandepartment of applied mathematics, shanghai jiaotong university, shanghai 200240, china department of applied mathematics Shanghai Jiaotong University Shanghai China

IN ref. [1] we have established the stability criteria for the finite delay difference systems ofthe general form in terms of the discrete Liapunov functionals as well as Liapunov *** then, some other results have app... 详细信息

关键词： quadratic delay difference systems uniform stability uniform asymptotic stability stability region asymptotic stability region.

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, china. 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

Simulation of nuclei morphologies for binary alloy

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Science china 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, china 2Key Lab of mathematics and applied mathematics, Center for applied Physics and Technology and School of Mathematical Sciences, Peking university, Beijing 100871, china 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

OPTIMAL CONTROL applied IN AUTOMATIC CLUTCH ENGAGEMENTS OF VEHICLES

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Chinese Journal of Mechanical Engineering 2004年第2期17卷 280-283页

作者： Sun Chengshun zhang Jianwu School of Mechanical and Power Engineering,shanghai jiaotong university,shanghai 200030, china School of Mechanical and Power Engineering Shanghai Jiaotong University Shanghai 200030 China department of Science and Technology Studies University College London WC1E 6BT UK

Start-up working condition is the key to the research of optimal engagementof automatic clutch for AMT. In order to guarantee an ideal dynamic performance of the clutchengagement, an optimal controller is designed by considering throttle angle, engine speed, gearratio, vehicle acceleration and road condition. The minimum value principle is also introduced toachieve an optimal dynamic performance of the nonlinear system compromised in friction plate wearand vehicle drive quality. The optimal trajectory of the clutch engagement can be described in theform of explicit and analytical expressions and characterized by the deterministic and accuratecontrol strategy in stead of indeterministic and soft control techniques which need thousands ofexperiments. For validation of the controller, test work is carried out for the automated clutchengagements in a commercial car with an traditional mechanical transmission, a hydraulic actuator, agroup of sensors and a portable computer system. It is shown through experiments that dynamicbehaviors of the clutch engagement operated by the optimal control are more effective and efficientthan those by fuzzy control.

关键词： Automatic clutch Optimal control Nonlinear system dynamics

A NEW NUMERICAL METHOD FOR GROUNDWATER FIOW AND SOLUTE TRANSPORT USING VELOCITY FIELD

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Journal of Hydrodynamics 2008年第3期20卷 356-364页

作者： zhang Qian-fei LAN Shou-qi WANG Yan-ming XU Yong-fu School of Naval Architecture Ocean and Civil Engineering Shanghai Jiaotong University Shanghai 200030China shanghai Municipal Engineering Design Institute Shanghai 200092 China department of Geotechnical Engineering Tongji University Shanghai 200092 China

A new numerical method for groundwater flow analysis was introduced to estimate simultaneously velocity vectors and water pressure head. The method could be employed to handle the vertical flow under variably saturated conditions and for horizontal flow as well. The method allows for better estimation of velocities at the element nodes which can be used as direct input to transport models. The advection-dispersion process was treated by the Eulerian-Lagrangian approach with particle tracking technique using the velocities at FEM nodes. The method was verified with the classical one dimensional model and applied to simulate contaminant transport process through a slurry wall as a barrier to prevent leachate pollution from a sanitary landfill.

关键词： groundwater flow solute transport velocity vectors finite element method Eulerian-Lagrangian approach particletracking technique

计及分布式电源的配电网潮流和断线故障分析算法

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上海交通大学学报 2008年第12期42卷 2028-2032,2036页

作者：刘波张焰杨娜上海交通大学电气工程系上海200240

介绍了分布式电源(DG)与配电网互联的两种常用接口方式,对异步发电机和太阳能电池两种典型DG的运行方式和控制特性进行了研究.建立了各自在潮流计算中所需的数学模型,提出了计及两种DG的交直流混合迭代潮流计算方法,并在此基础上通过考... 详细信息

介绍了分布式电源(DG)与配电网互联的两种常用接口方式,对异步发电机和太阳能电池两种典型DG的运行方式和控制特性进行了研究.建立了各自在潮流计算中所需的数学模型,提出了计及两种DG的交直流混合迭代潮流计算方法,并在此基础上通过考虑配电网特性对灵敏度分析法进行简化,使得该方法能够快速求解断线故障模式下的系统状态,也适合于计及不同DG形式的多电源配电网系统.通过对Kumamoto 15节点配电网系统进行测试,验证了所提出的潮流计算方法以及故障算法的有效性和合理性,为进一步研究DG对电网的影响奠定了基础.

关键词：分布式电源潮流计算灵敏度配电网故障分析

Hepatocellular carcinoma HepG2 cell apoptosis and caspase-8 and Bcl-2 expression induced by injectable seed extract of Coix lacryma-jobi

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Hepatobiliary & Pancreatic Diseases International 2011年第3期10卷 303-307页

作者： department of General Surgery (Lu Y and zhang BY),department of Bio-Information (Jia ZX),Affiliated Medical College Hospital,Qingdao university,Qingdao 266003,china shanghai jiaotong university School of Medicine,shanghai 200025,china (Wu WJ) department of Medicine,Heze Medical College,Heze 274000,china (Lu ZQ) [a] department of General Surgery Affiliated Medical College Hospital Qingdao University Qingdao 266003 China [b] department of Bio-Information Affiliated Medical College Hospital Qingdao University Qingdao 266003 China [c] shanghai jiaotong university School of Medicine Shanghai 200025 China [d] department of Medicine Heze Medical College Heze 274000 China

BACKGROUND:Many Chinese herbs,especially herbal injections,have been shown to have anti-tumor effects in recent ***,since most reports focus on the clinical effectiveness of these herbs,their mechanisms of action are not well *** this study,we assessed apoptosis in the hepatocellular carcinoma (HCC) cell line HepG2 induced by an injectable extract from the seed of Coix lacryma-jobi (Semen coicis,SC),and monitored the expression of Bcl-2 and ***:Injectable SC was applied to HepG2 cells at different concentrations and the cells were collected 12,24 and 48 hours later.5-fluorouracil was used as a positive control group,and fluorescence-activated cell-sorting cytometry was used to measure the apoptosis rate of HepG2 cells and the expression of Bcl-2 and caspase-8 ***:SC induced apoptosis in HepG2 cells in a concentration and time-dependent manner,and the expression of caspase-8 was elevated and ***,it did not significantly influence the expression of ***:Injectable SC may induce apoptosis in HCC cells by regulating the expression of caspase-8.

关键词： Semen coicis traditional Chinese medicine Bcl-2 caspase-8 HepG2 cells apoptosis

The Analysis of the Geometric Structure of the Delayed Time Used in the Embedding Process in Predicting Chaotic Time Series

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生物数学学报 1997年第1期12卷 23-26页

作者： Gu Shengshi Holden A V zhang H(applied mathematics department,jiaotong university,shanghai 20030 P.R.china.)(physiology department centre for Nonlinear Studies,The university of Leeds,LS2 9JT,UK.) 上海交通大学应用数学系上海 200030 university of Loeds 美国

Using the logistic map,we implicitly analyse the geometric structure of the delayed time used in the embedding process in prediction of a chaotic time series.

关键词： Delayed time embedding process chaotic time series