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Study on the bulk wave radiation of finite-length SAW devices using FEM/BEM

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Progress in Natural Science:Materials International 2005年第5期15卷 402-406页

作者： WANG Weibiao1.*, ZHANG Xiaodong1. SHUI Yongan1. ZHANG De1.and HAN Tao2.1. State Key Laboratory of Modern Acoustics, Institute of Acoustics, Nanjing {1., Nanjing 2.0093, china 2.{2., shanghai 200030, china) State Key Laboratory of Modern Acoustics Institute of Acoustics Nanjing University Nanjing 210093 China shanghai {1. {2. Shanghai 200030 China

Based on the distributions of stress and free charge on the interface of the surface acoustic wave (SAW) device calculated with the combination of boundary element method and finite element method(FEM/BEM), the power of each of the three possible bulk waves radiated by the SAW device is calculated, and their contributions to the overall input conductance are separated respectively. Moreover, the formula of angular distributions of their power radiation into the substrate is derived. Consider the effect of mass loading, the resistance density,defined as a scalar, is extended to generalized resistance densities which can be written as three 4×4 tensors and for which the formulas are derived. The bulk wave radiations for a synchronous one-port resonator on 42.Y-rotated LiTaO 3 are simulated. It is found that the radiated energy by slow shear wave contributes a very high proportion to input electrical energy in some frequency range.

关键词： SAW device bulk wave radiation FEM/BEM.

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. {1. Institute of Applied Mathematics and Mechanics, {1. {2., {1. 2.0072. china 2. department of Civil Engineering, {1. {2., {1. 2.0072. china 1. shanghai Institute of Applied Mathematics and Mechanics Shanghai University 200072 Shanghai China 2. {1. 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.

Population-size-dependent branching processes in Markovian random environments

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Chinese Science Bulletin 1998年第8期43卷 635-638页

作者： WANG Hanxing 1.and DAI Yonglong 2.1. {1. of Mathematics, shanghai {2., shanghai 2.1.00, china 2. {1. of Mathematics, Zhongshan {2., Guangzhou 51.2.5, china department of Mathematics Shanghai University Shanghai China department of Mathematics Zhongshan University Gunngzhou China

A branching model {Z n} n≥0is considered where the offspring distribution of the population’s evolution is not only dependent on the population size, but also controlled by a Markovian environmental process {ξ n} n≥0. For this model, asymptotic behaviour is studied such as limn→∞Z n and limn→∞Z n/m n in the case that the mean m k, θof the offspring distribution converges to m>1.as the population size k grows to ∞. In the case that {ξ n} n≥0is an irreducible positive recurrent Markov chain, certain extinction (i.e. P(Z n=0 for some n)=1. and noncertain extinction (i.e. P(Z n=0 for some n)1. are studied.

关键词： Markov chains in random environments stochastic population models branching processes.

One of the origins for curved edges of polyethylene singlecrystals

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Chinese Science Bulletin 1998年第7期43卷 564-568页

作者： YAN Deyue department of Applied Chemistry,{1.,{2., china department of Applied Chemistry Shanghai Jiaotong University Shanghai China

A new concept of lattice strain was developed to explain the origin of the curved edges of polyethylene (PE) single crystals. In the crystallization of PE from poor solvents, the length of critical nucleus generated is rather short. The thin lamellae are thermodynamically unstable especially at high temperature. Thereby, during the growth of PE single crystals an annealing process is going on simultaneously, which results in a reduction of thickness from the center to growing faces of lamellae. It is known that the thinner the single crystals, the bigger the unit-cell dimensions. Consequently, unit-cells in the central part of single crystals formed are somewhat smaller than those in the outer part of the same crystals. In order to fit in with the gradual enlargement of unit-cell dimensions from the center to the edges of single crystals, the lattice planes of a faster growing dominant {110} deform to be a set of parallel arcs of concentric circles. Accordingly, the edge of a slower growing subordinate {200} becomes a part of an ellipse with obvious curvature while the edge of a {110} sector remains almost straight for it is a small part of a large circumference.

关键词： PE single crystals curved lateral habit lattice strain.

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. {1. of Civil Engineering,shanghai {2.,shanghai 2.0072.china 2. School of Transportation Engineering,Tongji {2.,shanghai 2.0092.china 1. department of Civil Engineering Shanghai University Shanghai 200072 China 2. School of Transportation Engineering Tongji University Shanghai 200092 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.

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. {1. Institute of Applied Mathematics and Mechanics, {1. {2., {1. 2.0072. china 2. department of Building Engineering, Xi’an {2. of Technology, Xi’an 71.048, 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.

Construction of a genetic map and localization of QTLs for yield traits in tomato by SSR markers

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Progress in Natural Science:Materials International 2005年第9期15卷 793-797页

作者： LIU Yang 1.2., CHEN Huoying1.*, WEI Yutang2.and ZHUANG Tianming1.1. department of Plant Science, shanghai jiaotong university, {2. 2.1.01. china 2. department of Horticulture, Shenyang Agricultural university, Shenyang 1.01.1. china) department of Plant Science Shanghai Jiaotong University Shanghai 201101 China. department of Horticulture Shenyang Agricultural University Shenyang 110161 China

Using an F2.opulation derived from the hybrid of Lycopersicon esculentum Mill. ‘XF 98-7’× Lycopersicon pimpinellifolium LA2.84, a SSR genetic linkage map of tomato is constructed. The map contains 1.2.markers and spans 808.4 cM with an average distance of 7.2. cM between loci. Two quantitative trait loci （QTLs） for first flower node on chromosomes 5 and 1., two QTLs for number of flowers per truss on chromosomes 2.and 5, and five QTLs for fruit weight on chromosomes 1. 2. 3, 9 and 1.0}are identified.

关键词： tomato SSR markers genetic mapping first flower node number of flowers per truss fruit weight.

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,{1.,{2., P. R. china 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.

A Heuristic Algorithm for the Two-Machine Flowshop Group Scheduling Problem

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Journal of Systems Engineering and Electronics 2002年第4期13卷 8-16页

作者： Wang Xiuli & Wu Tihua department of Automation,{1.,{2., P.R. china department of Automation Shanghai Jiaotong University Shanghai 200030 P. R. China

This paper presents the two-machine flowshop group scheduling problem with the optimal objective of maximum lateness. A dominance rule within group and a dominance rule between groups are established. These dominance rules along with a previously established dominance rule are used to develop a heuristic algorithm. Experimental results are given and analyzed.

关键词： Group scheduling Flowshop Heuristic algorithm.

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