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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 UniversityShanghai 200092 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.

Electrochemical characteristic of Decarburization reaction

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International Journal of Minerals,Metallurgy and Materials 1999年第1期13卷 27-30页

作者： Xionggang Lu Fushen Li Lifen Li Kouchih chou (applied science School, university of science and Technology Beijing, Beijing 100083, china)(Material science and engineering School, shanghai university, shanghai 200072, china) applied science School University of Science and Technology Beijing Beijing 100083 China Material science and engineering School Shanghai University Shanghai 200072 China

The electrochemical mechanism of the reaction between Fe-c melts and caO-SiO2-Al2O3-FeOx slag systems has been carried out. The experimental results suggest that the final content of carbon in melt increases as the partial oxygen pressure of gas decreases no matter whether there is electronic conductor or not. However, the final content of carbon in the system with electronic conductor is much lower than that without electronic conductor. It can be deduced that the transfer ability of oxygen in slag is dominated by electrons. When an electronic conductor exists, an easy pathway for the electrons is provided and the oxygen transfer rate is accelerated.

关键词： melt-slag reaction decarburization electrochemistry electronic conductor

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 1. shanghai Institute of applied Mathematics and Mechanics Shanghai University 200072 Shanghai China 2. department of civil engineering Shanghai University 200072 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.

The complex variable reproducing kernel particle method for elasto-plasticity problems

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science china(physics,Mechanics & Astronomy) 2010年第5期53卷 954-965页

作者： cHEN Li1 & cHENG YuMin2 1 department of engineering Mechanics,chang’an university,Xi’an 710064,china 2 shanghai Institute of applied Mathematics and Mechanics,shanghai university,shanghai 200072,china 1. department of engineering Mechanics Chang’an University Xi’an 710064 China2. Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China

On the basis of reproducing kernel particle method(rKpM),using complex variable theory,the complex variable reproducing kernel particle method(cVrKpM) is discussed in this *** advantage of the cVrKpM is that the correction function of a two-dimensional problem is formed with one-dimensional basis function when the shape function is *** the cVrKpM is applied to solve two-dimensional elasto-plasticity *** Galerkin weak form is employed to obtain the discretized system equation,the penalty method is used to apply the essential boundary *** then,the cVrKpM for two-dimensional elasto-plasticity problems is formed,the corresponding formulae are obtained,and the Newton-raphson method is used in the numerical *** numerical examples are given to show that this method in this paper is effective for elasto-plasticity analysis.

关键词： meshless method reproducing kernel particle method(rKpM) complex variable reproducing kernel particle method(cVrKpM) correction function elasto-plasticity

Optimal motion planning of an underactuated spacecraft using wavelet approximate method

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progress in Natural science:Materials International 2006年第8期16卷 868-873页

作者： GE Xinsheng, cHEN Liqun and LIU Yanzhu (Beijing Institute of Machinery, Beijing 100085, china department of Mechanics, shanghai university, shanghai 200072, china department of engineering Mechanics, shanghai Jiaotong university, shanghai 200030, china) [a]Beijing Institute of Machiner Beijing China [b]department of Mechanics Shanghai University Shanghai China [c]department of engineering Mechanics Shanghai Jiaotong University Shanghai China

An optimal motion planning scheme using wavelet approximation is proposed for an underactuated spacecraft. The motion planning of an underactuated spacecraft can be formulated as an optimal control of a drift-free system. A cost functional is used to incorporate the control energy and the final state errors. The motion planning is to determine control inputs to minimize the cost functional. Using the method of wavelet, one can transform an infinite-dimensional optimal control problem to a finite-dimensional one and use Gauss-Newton algorithm to solve it for a feasible trajectory which satisfies nonholonomic constraints. The proposed scheme has been applied to a rigid spacecraft with two momentum wheels. The numerical simulation results indicate that optimal control with wavelet approximation is an effective approach to steering an underactuated spacecraft system from the initial configuration to the final configuration.

关键词： underactuated spacecraft motion planning optimal control nonholonomic constraint wavelet analysis.

Spatial continuity incorporated multi-attribute fuzzy clustering algorithm for blood vessels segmentation

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science china(Information sciences) 2010年第4期53卷 752-759页

作者： HAO JuTao1*, ZHAO JingJing2 & LI MingLu3 1School of Optical-Electrical and computer engineering, university of shanghai for science and Technology, shanghai 200093, china 2department of Electrical engineering, shanghai university of Electric power, shanghai 200090, china 3department of computer science and engineering, shanghai Jiaotong university, shanghai 200240, china 1. School of Optical-Electrical and computer engineering University of Shanghai for Science and Technology Shanghai 200093 China2. Department of Electrical Engineering Shanghai University of Electric Power Shanghai 200090 China3. Department of Computer Science and Engineering Shanghai Jiaotong University Shanghai 200240 China

A three-dimensional representation of vasculature can be extremely important in image-guided neurosurgery, pre-surgical planning. In this paper, a spatial continuity incorporated multi-attribute fuzzy clustering algorithm (MAFcM S) is proposed to segment entire blood vessels from TOF MrA images. This clustering method takes both the intensity information and the geometrical information into account, while most of the cur- rent clustering methods only deal with the former. In this method, a new dissimilarity measure, which integrates the intensity and the geometry shape dissimilarity, is introduced. Because of the presence of the geometrical information, the new measure is able to differentiate the pixels with similar intensity values within different geometrical shape structures. Experimental results show that the new algorithm can get better segmentation.

关键词： fuzzy c-means clustering scale space analysis spatial continuity blood vessel segmentation multi-attribute fuzzy clustering

Virtual multi-dimensional internal bonds model and its application in simulation of rock mass

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science china(Technological sciences) 2008年第2期51卷 192-201页

作者： ZHANG ZhenNan1,2 & GE Xiurun3,4 1 department of civil engineering,shanghai university,shanghai 200072,china 2 shanghai Institute of applied Mathematics and Mechanics,shanghai university,shanghai 200072, china 3 Institute of Geotechnical engineering,shanghai Jiao Tong university,shanghai 200030,china 4 Institute of rock and Soil Mechanics,chinese Academy of sciences,Wuhan 430071,china 1. department of civil engineering Shanghai University Shanghai 200072 China 2. shanghai Institute of applied Mathematics and Mechanics Shanghai University Shanghai 200072 China 3. Institute of Geotechnical engineering Shanghai Jiao Tong University Shanghai 200030 China 4. Institute of rock and Soil Mechanics Chinese Academy of Sciences Wuhan 430071 China

VMIB (virtual multi-dimensional internal bonds) is a multiscale mechanical model developed from the VIB (virtual internal bond) theory. In VIB theory,the solid mate-rial is considered to consist of random-distributed material particles in microscale. These particles are connected with normal bonds. The macro constitutive relation is derived from the cohesive law between particles. However,in VMIB,the micro particles are connected with both normal and shear bonds. The macro constitutive relation is derived in terms of bond stiffness coefficients. It has been theoretically certified that there exists a corresponding relationship between the two bond stiffness coefficients and the two macro material constants,i.e. the Young’s modulus and poisson ratio. This corresponding relationship suggests that it should be necessary and sufficient to simultaneously account for the normal and shear interactions between particles. Due to the fact that the fracture criterion is directly incorporated into the constitutive relation,both VIB and VMIB present many advantages in simulating fractures of materials. In the damage model of rock mass,a damage tensor is usually defined to describe the distribution of cracks. The damage value in one direction determines the relative stiffness of rock mass in this direction. In VMIB solid,the relative distribution density of micro bonds in one direction determines the relative macro stiffness of the material in this direction. The effects of the damage value and the relative distribution density of bonds are consistent. To simulate the failure behavior of rock mass with VMIB,the presented paper sets up a quantitative relationship between the damage tensor and the rela-tive distribution density of bonds. comparison of the theoretical and the experi-mental results shows that VMIB model can represent the effect of distributed cracks on rock mass with this relationship. The presented work provides a founda-tion for further simulating fracture behavior

关键词： VMIB (virtual multi-dimensional internal bonds) rock mass VIB (virtual internal bonds) multi-cracked body numerical simulation

A complex variable meshless method for fracture problems

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science china(physics,Mechanics & Astronomy) 2006年第1期49卷 46-59页

作者： cHENG Yumin1 & LI Jiuhong2 1. shanghai Institute of applied Mathematics and Mechanics, shanghai university, shanghai 200072, china 2. department of Building engineering, Xi’an university of Technology, Xi’an 710048, china shanghai Institute of applied Mathematics Mechanics Shanghai University Shanghai 200072 China department of Building engineering Xi’an University of Technology Xi’an 710048 China

Based on the moving least-square (MLS) approximation, the complex variable moving least-square approximation (cVMLS) is discussed in this paper. The complex variable moving least-square approximation cannot form ill-conditioned equations, and has greater precision and computational efficiency. Using the analytical solution near the tip of a crack, the trial functions in the complex variable moving least-square approxi- mation are extended, and the corresponding approximation function is obtained. And from the minimum potential energy principle, a complex variable meshless method for fracture problems is presented, and the formulae of the complex variable meshless method are obtained. The complex variable meshless method in this paper has greater precision and computational efficiency than the conventional meshless method. Some examples are given.

关键词： moving least-square approximation, complex variable moving least-square approximation, meshless method, complex variable meshless method, fracture.

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