检索结果-南通市图书馆

Rigidity for rational maps with Cantor Julia sets

在线全文

学校读者我要写书评

暂无评论

science china Mathematics 2008年第1期51卷 79-92页

作者： ZHAI Yu department of Mathematics, zhejiang university,{2., china department of Mathematics Zhejiang University Hangzhou 310027 China

In this paper, we prove that two rational maps with the Cantor Julia sets are quasicon- formally conjugate if they are topologically conjugate.

关键词： Cantor Julia set rigidity puzzle piece bounded shape quasiconformally conjugate 37F12

Preparation of TiC/Ni_3Al Composites by Upward Melt Infiltration

在线全文

学校读者我要写书评

暂无评论

Journal of Materials science & Technology 2000年第4期16卷 387-392页

作者： Yi PAN (department of Materials science and {2., zhejiang university, hangzhou 310027, china) Kewei SUN (National {2. Research Center of Solid Waste Resources Recovery, Kunming university of science and Technology,Kunming 650093, china) department of Materials science and {2. Zhejiang University Hangzhou 310027 China National engineering Research Center of Solid Waste Resources Recovery Kunming University of Science and Technology Kunming 650093 China

TiC/Ni_3Al composites have been prepared using upward infiltration method. The densification was performed by both Ni_3Al melt filling and TiC sintering during the infiltration. The dissolution of TiC in liquid Ni_3Al has been evidenced by finding Ni_3(Al,Ti)C after fast cooling in the TiC/Ni_3Al composites. The dissolution may be responsible for the infiltration and sintering. Compared with downward infiltration, the upward infiltration brought about higher strength and fracture toughness and shorter infiltration time. TiC/2. vol. pct Ni_3Al composite processed by upward infiltration had a flexural strength of 1476 MPa with a statistic Weibull modulus of 2..2.and a fracture toughness of 2..4 MPa . Better mechanical properties may be attributed to melt unidirectional movement in upward infiltration.

关键词： TiC Preparation of TiC/Ni3Al Composites by Upward Melt Infiltration Ni Al

Bridging properties of the debonded interface with frictional sliding

在线全文

学校读者我要写书评

暂无评论

Progress in Natural science:Materials International 2006年第2期16卷 153-162页

作者： LIU Pengfei, TAO Weiming, YU Xuezhong and GUO Yimu ( department of engineering Mechanics,{2., hangzhou 310027, china Second Affiliated Hospital,{2., hangzhou 310009, china) [a]department of engineering Mechanics Zhejiang University Hangzhou China [b]Second Affiliated Hospital Zhejiang University Hangzhou China

A theoretical model simulating the properties of frictional bridging is presented and relatively perfect stress solutions for the fiber and matrix are obtained. Based on the energy equilibrium in the process of interfacial debonding, an expression for the energy release rate G is derived to explore the interfacial fracture properties. By introducing an interfacial debonding criterion G≥Γi, a method for determining the critical debond length is proposed and the bridging constitutive relationship is also obtained. Numerical calculations are conducted for the fiber-reinforced composite SCS-6/Ti-6Al-4V and the results are also compared with those obtained by using other existing models.

关键词： interfacial stress transfer frictional sliding energy release rate bridging constitutive relationship fiber-reinforced composites.

A theoretical model of turbulent fiber suspension and its application to the channel flow

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science china(Physics,Mechanics & Astronomy) 2010年第9期53卷 1659-1670页

作者： LIN JianZhong1,2.& SHEN SuHua1 1 department of Mechanics,zhejiang {2.,hangzhou 310027,china 2.6} Jiliang {2.,hangzhou 310018,china 1. department of Mechanics Zhejiang University Hangzhou 310027 China2. China Jiliang University Hangzhou 310018 China

A theoretical model of turbulent fiber suspension is developed by deriving the equations of Reynolds averaged Navier-Stokes,turbulence kinetic energy and turbulence dissipation rate with the additional term of *** order to close the above equations,the equation of probability distribution function for mean fiber orientation is also *** theoretical model is applied to the turbulent channel flow and the corresponding equations are solved *** numerical results are verified by comparisons with the experimental *** effects of Reynolds number,fiber concentration and fiber aspect-ratio on the velocity profile,turbulent kinetic energy and turbulent dissipation rate are *** on the numerical data,the expression for the velocity profile in the turbulent fiber suspension channel flow,which includes the effect of Reynolds number,fiber concentration and aspect-ratio,is proposed.

关键词： theoretical model turbulent fiber suspension numerical simulation channel flow modification of velocity profile

Extension of a quantized enveloping algebra by a Hopf algebra

在线全文

学校读者我要写书评

暂无评论

science china Mathematics 2010年第5期53卷 300-307页

作者： WU ZhiXiang department of Mathematics,zhejiang {2.,hangzhou 310027,china 1. department of Mathematics Zhejiang University Hangzhou 310027 China

Suppose that H is a Hopf algebra,and g is a generalized Kac-Moody algebra with Cartan matrix A =(aij)I×I,where I is an index set and is equal to either {1,2....,n} or the natural number set *** f,g be two mappings from I to G(H),the set of group-like elements of H,such that the multiplication of elements in the set {f(i),g(i)|i ∈I} is *** we define a Hopf algebra Hgf Uq(g),where Uq(g) is the quantized enveloping algebra of g.

关键词： quantum enveloping algebra Hopf algebra Kac-Moody algebra

Stochastic stability of quasi-integrable Hamiltonian systems with time delay by using Lyapunov function method

在线全文

学校读者我要写书评

暂无评论

science china(Technological sciences) 2010年第3期53卷 703-712页

作者： LING Quan 1,JIN XiaoLing 1 &HUANG ZhiLong 2.1 department of Mechanics,zhejiang {2.,hangzhou 310027,china 2.State Key Laboratory of Fluid Power Transmission and Control,zhejiang {2.,hangzhou 310027,china 1. department of Mechanics Zhejiang University Hangzhou 310027 China2. State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China

The asymptotic Lyapunov stability of one quasi-integrable Hamiltonian system with time-delayed feedback control is studied by using Lyapunov functions and stochastic averaging ***,a quasi-integrable Hamiltonian system with time-delayed feedback control subjected to Gaussian white noise excitation is approximated by a quasi-integrable Hamiltonian system without time ***,stochastic averaging method for quasi-integrable Hamiltonian system is used to reduce the dimension of the original system,and after that the Lyapunov function of the averaged It equation is taken as the optimal linear combination of the corresponding independent first integrals in ***,the stability of the system is determined by using the largest eigenvalue of the linearized *** examples are used to illustrate the proposed procedure and the effects of delayed time on the Lyapunov stability are discussed as well.

关键词： Lyapunov stability Lyapunov function time delay stochastic averaging

RESEARCH ON ADAPTIVE DATA COMPRESSION METHOD FOR TRIANGULATED SURFACES

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical engineering 2004年第2期17卷 189-192页

作者： Wang Wen Wu Shixiong Chen Zichen department of Mechanical engineering,{2. university,hangzhou 310027, china department of Mechanical engineering Zhejiang University Hangzhou 310027 China

NC code or STL file can be generated directly from measuring data in a fastreverse-engineering mode. Compressing the massive data from laser scanner is the key of the newmode. An adaptive compression method based on triangulated-surfaces model is put ***-vector angles between triangles are computed to find prime vertices for removal. Ring datastructure is adopted to save massive data effectively. It allows the efficient retrieval of allneighboring vertices and triangles of a given vertices. To avoid long and thin triangles, a newre-triangulation approach based on normalized minimum-vertex-distance is proposed, in which thevertex distance and interior angle of triangle are considered. Results indicate that the compressionmethod has high efficiency and can get reliable precision. The method can be applied in fastreverse engineering to acquire an optimal subset of the original massive data.

关键词： Data compression Reverse engineering Triangulated surfaces

Exact stationary solutions independent of energy for strongly nonlinear stochastic systems of multiple degrees of freedom

在线全文

学校读者我要写书评

暂无评论

science china(Technological sciences) 2009年第8期52卷 2424-2431页

作者： HUANG ZhiLong1,2.& JIN XiaoLing1 1 department of Mechanics, zhejiang university,{2., china 2.The State Key Laboratory of Fluid Power Transmission and Control, zhejiang university,{2., china department of Mechanics Zhejiang University Hangzhou 310027 China The State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China

A new procedure is proposed to construct strongly nonlinear systems of multiple degrees of freedom subjected to parametric and/or external Gaussian white noises, whose exact stationary solutions are independent of energy. Firstly, the equivalent Fokker-Planck-Kolmogorov (FPK) equations are derived by using exterior differentiation. The main difference between the equivalent FPK equation and the original FPK equation lies in the additional arbitrary antisymmetric diffusion matrix. Then the exact stationary solutions and the structures of the original systems can be obtained by using the coefficients of antisymmetric diffusion matrix. The obtained exact stationary solutions, which are generally independent of energy, are for the most general class of strongly nonlinear stochastic systems multiple degrees of freedom (MDOF) so far, and some classes of the known ones dependent on energy belong to the special cases of them.

关键词： exact stationary solution nonlinear stochastic system equivalent system independent of energy

Thermo-responsive stick-slip behavior of advancing water contact angle on the surfaces of poly(N-isopropylacrylamide)-grafted polypropylene membranes

在线全文

学校读者我要写书评

暂无评论

science china Chemistry 2010年第1期53卷 183-189,289页

作者： WAN LingShu,MENG XiangLin,YANG YunFeng,TIAN Jing & XU ZhiKang Key Laboratory of Macromolecular Synthesis and Functionalization,Ministry of Education department of polymer {2. and engineering,zhejiang university,hangzhou 310027,china 1. Key Laboratory of Macromolecular Synthesis and Functionalization Ministry of Education department of polymer {2. and engineering Zhejiang University Hangzhou 310027 China

Wettability of a solid surface is highly important to its practical application,especially for the surface that shows thermoresponsive *** this paper,we describe a thermo-responsive stick-slip behavior of water droplets on the surfaces of poly(N-isopropylacrylamide)(PNIPAM)-grafted polypropylene *** emission scanning electron microscope(FESEM) images elucidate that the morphology of PNIPAM-grafted membrane surface is thermo-responsive,i.e.,the surface becomes rougher above the lower critical solution temperature(LCST) of *** the surface of nascent polypropylene membranes,the water droplet shows a smooth motion resulting in advancing and receding water contact angles of 111° and ～65°,*** the PNIPAM-grafted membrane surfaces,the water droplet shows a stick-slip pattern above the LCST,whereas it advances smoothly below the *** phenomenon is reproducible and can be ascribed to the energy barriers enhanced by the shrink of PNIPAM chains above the *** also find that the slip contact angle decreases from 102. to 92. after several stick-slip *** decrease is attributed to the water adsorption on the grafted PNIPAM layer,which is confirmed by the continuous decrease of the receding water contact angle.

关键词： stick-slip behavior water contact angle thermo-responsive surface poly(N-isopropylacrylamide) polypropylene membrane