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Effect of slow monomer addition on molecular parameters of hyperbranched polymers synthesized in the presence of multifunctional core molecules

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Science china Chemistry 2010年第4期53卷 891-897页

作者： ZHOU ZhiPing1, Jia ZhengWei1 & YAN DeYue2.1School of Materials Science and engineering, Jiangsu university, Zhenjiang 2.2.13, {2. 2.tate Key Laboratory of Metal Matrix Composites, Shanghai jiao tong university, Shanghai 2.02.0, {2. 1. School of Materials Science and engineering Jiangsu University Zhenjiang 212013 China2. State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong University Shanghai 200240 China

This study develops the kinetics for the slow monomer addition technique in the synthesis of hyperbranched polymers. Taking the conversion of monomer (x) as a variable, we derived the analytic expressions of molecular size distribution function, average degree of polymerization, polydispersity index and degree of branching. These expressions are not only amenable to the polymerization with high monomer conversion, but also appropriate to describe the whole polymerization process. Comparison with the one-pot polymerization indicates that the slow monomer addition technique improves the molecular weight distribution and increases the degree of branching for the products obtained.

关键词： hyperbranched polymer kinetics molecular weight distribution polydispersity degree of branching

Two-stop-two-slip motions of a dry friction oscillator

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Science china(Technological Sciences) 2010年第3期53卷 623-632页

作者： YANG ShaoPu1 & GUO ShuQi2.1 School of Mechanical engineering,Shijiazhuang Railway institute,Shijiazhuang 050043,{2. 2.Department of engineering Mechanics,Shijiazhuang Railway institute,Shijiazhuang 050043,{2. 1. School of Mechanical engineering Shijiazhuang Railway Institute Shijiazhuang 050043 China2. Department of Engineering Mechanics Shijiazhuang Railway Institute Shijiazhuang 050043 China

This paper presents the investigation on the two-stop-two-slip (TSTS) motions in a dry friction *** is a kind of dissipated *** dry friction oscillator implies complicated stick-slip *** to its nonlinear non-smooth characters,it is difficult to analyze the stick-slip ***,TSTS motion is analyzed in this paper.A closed form solution of the TSTS motions is *** addition,parameter domain for the motion is *** general,there are no explicit solutions to transcendental equation in the closed form ***,explicit solutions are possible for special ***, Poincare map is structured to analyze the stability of the motions.

关键词： dry friction non-smooth dynamics stick-slip motion

WATER TUNNEL EXPERIMENTAL INVESTIGATION ON THE DRAG REDUCTION CHARACTERISTICS OF THE TRAVELING WAVY WALL

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Journal of Hydrodynamics 2011年第1期23卷 65-70页

作者： YAO Yan LU Chuan-jing SI Ting ZHU Kun Department of engineering Mechanics Shanghai Jiao Tong University Shanghai 200240 China Beijing Electromechanic engineering institute Beijing 100074 China State Key Laboratory of Ocean engineering Shanghai Jiao Tong University Shanghai 200030 China Department of modem Mechanics University of Science and Technology of China Hefei 230027 China

Drag reduction experiment of the traveling wavy wall at high Reynolds number is conducted.A suit of traveling wavy wall device is *** drag forces of the traveling wavy wall with various wave speeds（c）are measured under different water speeds（U）in the K15 cavitation water tunnel and are compared with that of the flat *** results show that the mean drag force of the traveling wavy wall have decreased and then increased with oscillation frequency increasing at the same flow *** different flow speeds,when traveling wave wall reached to the minimum of drag force,the corresponding the ratio of the wall motion phase speed c to flow speed U,c /U is slightly *** the parameters of the experiment,whenc /U reaches a certain value,the drag force of the traveling wavy wall can be less than that of the flat *** drag reduction can be up to 42..Furthermore,as the value ofc /U increases,the traveling wavy wall can restrain the separation and improve the quality of flow field.

关键词： flow control drag reduction traveling wavy wall water tunnel test

EXPERIMENTAL INVESTIGATION ON THE DRAG REDUCTION CHARACTERISTICS OF TRAVELING WAVY WALL AT HIGH REYNOLDS NUMBER IN WIND TUNNEL

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Journal of Hydrodynamics 2010年第5期22卷 719-724页

作者： YAO Yan LU Chuan-jing SI Ting ZHU Kun Department of engineering Mechanics Shanghai Jiao Tong University Shanghai 200240 China Beijing Electromechanic engineering institute Beijing 100074 China State Key Laboratory of Ocean engineering Shanghai Jiao Tong University Shanghai 200030 China Department of Modern Mechanics University of Science and Technology of China Hefei 230027 China

Drag reduction experiments of the traveling wavy wall at high Reynolds number, ranging from 1.46×106 to 5.83×106 based on the free-stream velocity and the model length, were conducted. A suit of traveling wavy wall device was developed and its characteristics of drag reduction at high Reynolds number were investigated. The drag forces of the traveling wavy wall with various wave speeds （ c ） were measured at different wind speeds （U ） in the FL-8 low-speed wind tunnel and compared with the drag force of the flat plate. The results show that the mean drag force of the traveling wavy wall decreases as the value of c /U increases, at different wind velocities, the values of c /U corresponding to minimal drag force of the traveling wavy wall are different, when the values of c /U are larger than 0.6, the mean drag forces of the traveling wavy wall are smaller than those of the flat plate, and the drag reduction can be up to 60%. The drag reduction effectiveness of traveling wavy wall is thus achieved. Furthermore, as the value of c /U increases, the traveling wavy wall can restrain the separation and improve the quality of flow field.

关键词： flow control drag reduction traveling wavy wall wind tunnel test

Optimization of Band Gap of 1D Elastic Metamaterial Under Impact Load by Regulating Stiffness

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Acta Mechanica Solida Sinica 2024年第1期37卷 148-154页

作者： tong Li Xianlong Jin Yongqiang Li Peizhong Yang School of Mechanical engineering Shanghai Jiao Tong UniversityShanghai 200240China State Key Laboratory of Mechanical System and Vibration Shanghai Jiaotong UniversityShanghai 200240China College of Science Northeastern UniversityShenyang 110819China

Designing materials that mitigate impacts effectively are crucial for protecting people and ***,a single-resonator metamaterial with negative mass characteristics is proposed for impact mitigation,and numerical analysis of wave propagation shows explicitly how the spring stiffness and number of unit cells influence that *** results show clearly that a metamaterial with differing microstructural stiffness is better at mitigating the effect of a shock wave than one with a unique ***,there is a critical number of unit cells beyond which the shock wave is not attenuated further,but the fabrication complexity *** the 40 groups of microstructural regions in this example,the attenuation effect no longer increases when there are more than 35 *** work offers guidance for microstructure designs in metamaterials and provides new ideas for using metamaterials to mitigate shock waves.

关键词： Elastic metamaterials Wave attenuation Stiffness Number of unit cells

New Receiving Mode of Extinction for Determining Particle Size and Density without Convex Lens

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Chinese Journal of Lasers 2002年第1期11卷 46-51页

作者： WU Weiliang CHEN Hanping (School of Power and Energy engineering, Shanghai jiao {2. university, Shanghai 2.0030, china) CAI Xiaoshu WANG Naining (School of Power and Energy engineering, university of Shanghai for Science and Technology, Shanghai 2 School of Power and Energy engineering Shanghai Jiao Tong University 上海 200030 School of Power and Energy engineering University of Shanghai for Science and Technology 上海 200093

In this article a new receiving mode for scattering light by particle is theoretically discussed. Using this receiving mode the convex lens can be omitted during determining the extinction of particle. Therefore the extinction coefficient of sphere particles is redefined by extrapolating the conventional one. In terms of the calculation results of light scattering the definition of near-field extinction coefficient of a swarm particle is depicted. Through the error analysis it is proved that the error coming from the new definition of extinction coefficient is acceptable for engineering application. In addition, a technique for determining the particle size and density is presented in this article and the advantage using this receiving mode is described.

关键词： extinction of particle light scattering fluctuation method particle size particle density

The sloshing of stratified liquid in a two-dimensional rectangular tank

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Science china(Physics,Mechanics & Astronomy) 2011年第1期54卷 2-9页

作者： WU GuoXiong1,2.1 State Key Laboratory of Ocean engineering,College of Naval Architecture,Ocean and Civil engineering,Shanghai {2. tong university,Shanghai 2.02.0,china 2.Department of Mechanical engineering,university College London,Torrington Place,London WC1E 7JE,UK 1. State Key Laboratory of Ocean engineering College of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai 20024 China2. Department of Mechanical Engineering University College Londo Torrington Place London WC1E 7JE UK

The sloshing of inviscid liquid of stratified density in a rectangular tank is *** the flow is no longer irrotional,the governing equation is found to be quite different from the Laplace equation used for the liquid of constant *** particular it contains terms of mixed temporal and spatial *** problem is solved based on the variable separation method and Laplace transform for the constant Vaisala-Brunt *** is found that the stratification of density may have small effects on those natural frequencies associated with the constant density,but many new natural frequencies have appeared as a result of its effect.

关键词： sloshing density stratification resonance rectangular tank

Research on Digitalization of High Frequency Microplasma Arc welding Machine with Small welding Current

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稀有金属材料与工程 2011年第S4期40卷 79-83页

作者： He Jianping1,Huang Chen1,jiao Fujie1,You Zhichun2.1College of Materials engineering,Shanghai {2. of engineering Science,Shanghai 2.162.,china2.hanghai WTL welding Equipment Manufacture Co.Ltd.,Shanghai 2.162.,china Shanghai Univ Engn Sci Coll Mat Engn Shanghai 201620 Peoples R China Shanghai WTL welding Equipment Mfg Co Ltd Shanghai 201620 Peoples R China

The problem of digital controlling of high frequency microplasma arc welding machine has been solved through Fujitsu 16-bits single-chip processor *** welding power sources and their control systems,digital sequential control system,and digital man-machine interaction system were included in digital microplasma arc welding machine ***,which is about digital sequential control system,digital man-machine interaction system,digital controller and its interface,and controlling software program,were *** has been showed that full digitalization of high frequency microplasma arc welding machine was fulfilled,minimum welding current of the machine is 0.05A,and arc is stable and can been started unfailingly.

关键词： digitalization microplasma arc welding machine single-chip processor

Study on diffusion welding SiCp/ZL101 with Cu interlayer

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Rare Metals 2003年第4期22卷 289-293页

作者： NIU Jitai, GUO Wei, ZHANG Xinmei, and LIU Xingqiu1) State Key Laboratory of Advanced welding Production Technology, Harbin institute of Technology, Harbin 150001, {2.2. State Key Laboratory of Metal Matrix Composite, Shanghai jiao tong university, Shanghai 2.0030, {2. State Key Laboratory of Advanced welding Production Technology Harbin Institute of Technology Martin 150001 China

Through the vacuum diffusion welding SiCp/ZL 101 aluminum with Cu interlayer,the effect of welding parameter and the thickness of Cu on the welded joint property wasinvestigated, and the optimal welding parameters were put forward at the same time. Themicrostructure of joint was analyzed by means of optical-microscope, scanning electron microscope inorder to study the relationship between the macro-properties of joint and the microstructure. Theresults show that diffusion welding with Cu interlayer could be used for welding aluminum matrixcomposites SiCp/ZL 101 successfully.

关键词： aluminum matrix composite SiCp/ZL 101 diffusion welding Cu interlayer