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Science china(Information Sciences) 2010年第1期53卷 89-100页

作者： JIN YongQiang1,2, LIU XiangDong1, QIU Wei2 & HOU ChaoZhen1 1Department of Automatic Control, Beijing Institute of Technology, Beijing 100081, china 2aerospace system engineering shanghai, shanghai 201108, china Department of Automatic Control Beijing Institute of Technology Beijing China aerospace system engineering shanghai Shanghai China

To solve the regulator problem of a class of uncertain MIMO nonlinear systems subject to control input constraint, three types of time-varying sliding mode control laws are proposed. The sliding surfaces pass the initial value of the system at the initial time, and are shifted/rotated towards the predetermined ones. The controller parameters are optimized by genetic algorithm (GA). Lyapunov method is adopted to prove the stability and robustness to the parameter uncertainties and external disturbance. By mean of time-varying sliding mode control law, the reaching phase in the conventional sliding mode control is eliminated, and the system is guaranteed to have robustness from the very beginning. Taking the control of two-link manipulator and attitude tracking of rigid spacecraft as two examples, we illustrate the features of the time-varying sliding mode control. The simulation results show the validity of the control law to a class of uncertain MIMO systems. Better robustness against the uncertainties and external disturbance could be achieved by time-varying sliding mode control without violating the constraint on control input.

关键词： time-varying sliding surface sliding mode control MIMO nonlinear system uncertain control input constraints

Induced electromagnetic stirring behavior in a resistance spot weld nugget

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Science china(Technological Sciences) 2010年第5期53卷 1271-1277页

作者： LI YongBing1,LIN ZhongQin1,2,LAI XinMin1,2,CHEN GuanLong1,2 & ZHANG Ke3 1 shanghai Key Laboratory of Digital Autobody engineering,shanghai Jiao Tong University,shanghai 200240,china 2 State Key Laboratory of Mechanical system and Vibration,shanghai Jiao Tong University,shanghai 200240,china 3 Welding engineering Institute,shanghai Jiao Tong University,shanghai 200240,china shanghai Key Laboratory of Digital Autobody engineering Shanghai Jiao Tong University Shanghai China State Key Laboratory of Mechanical system and Vibration Shanghai Jiao Tong University Shanghai China Welding engineering Institute Shanghai Jiao Tong University Shanghai China

A multi-physics hybrid numerical model,which couples electric,magnetic,thermal and flow fields,was used to investigate electromagnetic stirring behavior in a resistance spot weld *** differences of two kinds of different excitation inputs,i.e.,a sinusoidal current and its root-mean-square(RMS) value,were studied to examine if they could produce equivalent electromagnetic stirring effects in the weld *** showed that the two types of current inputs could produce almost identical fluid flow and heat transfer patterns and consistent evolution of flow and thermal fields in the *** the end of the welding cycles,the maximum flow velocity and temperature between the two inputs differed by 11.6% and 0.3%,***,the RMS current can be assumed to produce an approximately equivalent electromagnetic stirring effect with the sinusoidal current,and can be used in the future research to greatly improve the solution efficiency of the electromagnetic stirring behavior in the resistance spot weld nugget.

关键词： induced magnetic field electromagnetic stirring resistance spot welding fluid flow heat transfer

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上海新城·西岸公园装配式住宅技术集成项目

建筑实践 2024年第3期 120-127页

作者： Zhongsen Architectural & engineering Designing Consultants Ltd. shanghai PTArchitects 上海中森建筑与工程设计顾问有限公司 PTA上海柏涛

新城·西岸公园,坐落在上海市浦东新区周浦镇,约10km车程可覆盖前滩、张江、迪士尼,距11号线秀沿路站仅2.5km,距外环、18号线、万达均在2km之内。建筑布局:住宅建筑均为高层,占地面积小,使得小区内景观面积最大化。商业及售楼处等配套...

新城·西岸公园,坐落在上海市浦东新区周浦镇,约10km车程可覆盖前滩、张江、迪士尼,距11号线秀沿路站仅2.5km,距外环、18号线、万达均在2km之内。建筑布局:住宅建筑均为高层,占地面积小,使得小区内景观面积最大化。商业及售楼处等配套设施用房安排在临街位置,大量小区商品房得以享有安静的小区内部空间。全中心花园的设计,增加小区景观条件的均好性。

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An interpolating boundary element-free method (IBEFM) for elasticity problems

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Science china(Physics,Mechanics & Astronomy) 2010年第4期53卷 758-766页

作者： REN HongPing 1 , CHENG YuMin 2 & ZHANG Wu 1 1 School of Computer engineering and Science, shanghai University, shanghai 200072, china 2 shanghai Institute of Applied Mathematics and Mechanics, shanghai University, shanghai 200072, china School of Computer engineering and Science Shanghai University Shanghai China shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai China

The paper begins by discussing the interpolating moving least-squares (IMLS) method. Then the formulae of the IMLS method obtained by Lancaster are revised. On the basis of the boundary element-free method (BEFM), combining the boundary integral equation method with the IMLS method improved in this paper, the interpolating boundary element-free method (IBEFM) for two-dimensional elasticity problems is presented, and the corresponding formulae of the IBEFM for two-dimensional elasticity problems are obtained. In the IMLS method in this paper, the shape function satisfies the property of Kronecker δ function, and then in the IBEFM the boundary conditions can be applied directly and easily. The IBEFM is a direct meshless boundary integral equation method in which the basic unknown quantity is the real solution to the nodal variables. Thus it gives a greater computational precision. Numerical examples are presented to demonstrate the method.

关键词： moving least-squares (MLS) approximation interpolating moving least-squares (IMLS) method boundary integral equation meshless method boundary element-free method (BEFM) interpolating boundary element-free method (IBEFM) elasticity problem

Boundary element-free method for elastodynamics

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Science china(Physics,Mechanics & Astronomy) 2005年第6期48卷 641-657页

作者： CHENG Yumin1 & PENG Miaojuan2 1. shanghai Institute of Applied Mathematics and Mechanics, shanghai University, shanghai 200072, china 2. Department of Civil engineering, shanghai University, shanghai 200072, china shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai China Department of Civil engineering Shanghai University Shanghai China

The moving least-square approximation is discussed first. Sometimes the method can form an ill-conditioned equation system, and thus the solution cannot be obtained correctly. A Hilbert space is presented on which an orthogonal function system mixed a weight function is defined. Next the improved moving least-square approximation is discussed in detail. The improved method has higher computational efficiency and precision than the old method, and cannot form an ill-conditioned equation system. A boundary element-free method (BEFM) for elastodynamics problems is presented by combining the boundary integral equation method for elastodynamics and the improved moving least-square approximation. The boundary element-free method is a meshless method of boundary integral equation and is a direct numerical method compared with others, in which the basic unknowns are the real solutions of the nodal variables and the boundary conditions can be applied easily. The boundary element-free method has a higher computational efficiency and precision. In addition, the numerical procedure of the boundary element-free method for elastodynamics problems is presented in this paper. Finally, some numerical examples are given.

关键词： moving least-square approximation, improved moving least-square approximation, elastodynamics, boundary integral equation, meshless method, boundary element-free method, Fourier eigen transform.

Nonlinear constitutive law for ferroelectric/ferroelastic material and its finite element realization

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Science china(Physics,Mechanics & Astronomy) 2007年第1期50卷 70-86页

作者： LI YaoChen Department of aerospace engineering and Applied Mechanics,Tongji University,shanghai 200092,china Department of aerospace engineering and Applied Mechanics Tongji University Shanghai China

The hysteresis phenomena of ferroelectric/ferroelastic material in polarization procedure are investigated. Some assumptions are presented based on the published experimental data. The electrical yielding criterion, mechanical yielding criterion and isotropic hardening model are established. The flow theory in incremental forms in polarization procedure is presented. The nonlinear constitutive law for electrical-mechanical coupling is proposed phenomenologically. Finally, the nonlinear constitutive law expressed in a form of matrices and vectors, which is immediately associated with finite element analysis, is formulated. In the example problem of a rectangular specimen subjected to a uniaxial electric field, the procedure from virgin state to fully polarized state is simulated. Afterward, a uniaxial compressive loading is applied to depolarizing the specimen. Results are in agreement with the experimental data.

关键词： ferroelectric/ferroelastic material constitutive law nonlinear finite element method.

Research on nonlinear constitutive relationship of permanent deformation in asphalt pavements

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Science china(Physics,Mechanics & Astronomy) 2006年第6期49卷 671-682页

作者： PENG Miaojuan1 & XU Zhihong2 1. Department of Civil engineering,shanghai University,shanghai 200072,china 2. School of Transportation engineering,Tongji University,shanghai 200092,china Department of Civil engineering Shanghai University Shanghai China School of Transportation engineering Tongji University Shanghai China

To predict correctly the rut depths in asphalt pavements,a new nonlinear viscoelastic-elastoplastic constitutive model of permanent deformation in asphalt pave-ments is presented. The model combines a generalized Maxwell model with an elasto-plastic one. Then from the creep theory,the linear and nonlinear constitutive equations of the generalized Maxwell model are obtained. From the nonlinear finite element method for the rutting of the asphalt pavement,the rut depths of 4 asphalt-aggregate mixtures are obtained. And the results are compared with the ones from the finite element method by SHRP and the experiments by SWK/UN. The results in this paper are better than the ones by SHRP,and agree with the ones of the experiment by SWK/UN. This shows that the nonlinear viscoelastic-elastoplastic constitutive model,which is presented in this paper for the rutting of the asphalt pavement,is effective. The properties,such as nonlinear elastic-ity,plasticity,viscoelasticity and nonlinear viscoelasticity,which affect the rutting of an asphalt pavement,can be shown in the model. And the characteristics of the permanent deformation of the asphalt pavement can be presented entirely in the model.

关键词： asphalt pavement,permanent deformation,nonlinear viscoelastic-elastoplastic constitutive relationship,generalized Maxwell model,creep compliance.

Model test on sand retaining wall reinforced with denti-strip inclusions

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Science china(Technological Sciences) 2008年第12期51卷 2259-2269页

作者： ZHANG MengXi1 & ZHOU Huai1,2 1 Department of Civil engineering,shanghai University,shanghai 200072,china 2 shanghai Chengtou City Land(Group) Corporation,shanghai 200438,china Department of Civil engineering Shanghai University Shanghai China shanghai Chengtou City Land (Group) Corporation Shanghai China

In conventional reinforced soil structures,the reinforcements are often laid hori-zontally in the *** this paper,a new concept of soil reinforced with denti-strip inclusions was proposed and a series of laboratory model tests were carried out on sand retaining wall reinforced with denti-strip *** the horizontal displacements of the facing,the lateral earth pressures acting on vertical elements were measured.A microscopic measurement was performed to investigate the deformation and progressive failure of the sand within model retaining *** on the image analytical technique,the bearing capability and interaction mechanism of reinforced sand retaining wall were *** model of the initial shear failure and potential failure surface were also put *** the experimental results,it is shown that denti-strip inclusions can increase the bearing capability of retaining wall significantly and restrict the facing displacements efficiently,as compared with conventional horizontal reinforcement.

关键词： denti-strip inclusions reinforced sand retaining wall model test horizontal facing displacements lateral earth pressure on denti-elements failure surface

Study of control effects of vortex generators on a supercritical wing

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Science china(Technological Sciences) 2010年第8期53卷 2038-2048页

作者： HUANG JingBo 1 ,XIAO ZhiXiang 1 ,FU Song 1 &ZHANG Miao 2 1 School of aerospace engineering,Tsinghua University,Beijing 100084,china 2 shanghai Aircraft Design and Research Institute of COMAC,shanghai 200232,china School of aerospace engineering Tsinghua University Beijing China shanghai Aircraft Design and Research Institute of COMAC Shanghai China

Flows around vortex generators(VGs),which serve as one of the important flow control methods,are investigated by solving Reynolds-averaged Navier-Stokes(RANS)*** influences on the main flow of VGs are intended to ***, the flow around a single VG on a flat plane is computed to validate the schemes and to acquire basic knowledge of this kind of ***,transonic flow past a standard model,named by ONERA-M6 wing,is predicted to investigate the flow features of shockwave/boundary-layer interactions(SWBLI).Thirdly,the effects of a row of VGs mounted about 25%local chord on a supercritical wing are analyzed in transonic condition with strong ***,VGs are mounted more upwind(about 3.5%local chord)to explore the effects at low speed and high incidence *** numerical results show that seven VGs can effectively suppress the separations behind the strong SWBLI and decrease spanwise flow and wing-tip vortex in transonic *** also can decrease the large scope of separation over the wing at low speed with high angle of attack.

关键词： supercritical wing vortex generator(VG) shockwave/boundary-layer interactions(SWBLI)

Response of Cytoskeleton of Murine Osteoblast Cultures to Two-step Freezing

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Acta Biochimica et Biophysica Sinica 2005年第12期37卷 814-818页

作者： Bao-Lin LIU~1 John McGRATH~21 Institute of Cryobiology,University of shanghai for Science and Technology,shanghai 200093,china 2 Department of aerospace and Mechanical engineering,University of Ariona,Tucson 85721,USA Institute of Cryobiology University of Shanghai for Science and TechnologyShanghai 200093 China Department of aerospace and Mechanical engineering University of ArizonaTucson 85721 USA

Understanding the ultrastructural response of cells to the freezing process is important fordesigning cryopreservation strategies for cells and *** cellular structures of attached cells are targetsof cryopreservation-induced *** fluorescence staining was used to assess the status of theactin filaments (F-actin) of murine osteoblasts attached to hydroxyapatite discs and plastic coverslips for atwo-step freezing *** F-actin of dead cells was depolymerized and distorted in the freezing *** that of live cells had little *** results suggest that the cytoskeleton may support the robustnessof cells during *** present study helps to investigate the damage mechanism of attachedcells during the freezing process.

关键词： cytoskeleton osteoblast actin filament two-step freezing