检索结果-南通市图书馆

STOCHASTIC prOpAGATION OF SEMI-ELLIpTICAL SUrFACE CrACK

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 1995年第3期8卷 236-244页

作者： Zhu Weiqiu Jiang Mingxiao (department of mechanics,zhejiang university,hangzhou,310027,p.r.china) department of mechanics Zhejiang University Hangzhou 310027 China

The semi-elliptical surface crack growth of structural components with uncertain material resistance under random loading is studied by using the stochastic averaging *** FpK equation governing the transition probability density function of crack lengths is *** analytical solution of the FpK equation for the case of that the equations for the crack growth in the surface and depth directions are uncoupled is *** effects of the parameters of the stress process and of the material property on the behavior of semi-elliptical fatigue crack growth of the components with deterministic resistance to crack growth in the stationary Gaussian stress process are *** comparison of the analytical result with digital simulation shows the effectiveness of the present method.

关键词： fatigue crack growth semi-elliptical surface crack fatigue life reliability stochastic averaging

THE FLOW IN rOTATING CUrVED CIrCULAr pIpE

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2000年第1期12卷 108-116页

作者： Zhang Jin suo, Shen Xin rong, Zhang Ben zhao department of mechanics, zhejiang university, hangzhou 310027, p.r.china zhejiang Univ Hangzhou China

The combined effects of the system rotation (Coriolis force) and curvature (centrifugal force) on the flow in rotating curved circular pipe with small curvature are examined by perturbation method. A second order perturbation solution is presented. The secondary flow structure and the primary axial velocity distributions are studied in detail. The loops of the secondary flow are more complex than those in a curved pipe without rotation or a rotating straight pipe. Its numbers depend on the body force ratio F which represents the ratio of the Coriolis to the centrifugal force. The maximum of the axial velocity is pushed to either outer bend or inner bend, which is also determined by F. The results are confirmed by the results of other authors who studied the same problem by different methods.

关键词： secondary flow curved pipe perturbation method

STOCHASTIC OpTIMAL CONTrOL OF HYSTErETIC SYSTEMS UNDEr EXTErNALLY AND pArAMETrICALLY rANDOM EXCITATIONS

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2003年第1期16卷 61-66页

作者： Ying Zuguang Zhu Weiqiu (department of mechanics,zhejiang university,hangzhou 310027,china) department of mechanics Zhejiang University Hangzhou 310027 China

A stochastic optimal control method for nonlinear hysteretic systems under externally and/or parametrically random excitations is presented and illustrated with an example of hysteretic column system. A hysteretic system subject to random excitation is first replaced by a nonlinear non-hysteretic stochastic system. An It$\hat {\rm o}$ stochastic differential equation for the total energy of the system as a one-dimensional controlled diffusion process is derived by using the stochastic averaging method of energy envelope. A dynamical programming equation is then established based on the stochastic dynamical programming principle and solved to yield the optimal control force. Finally, the responses of uncontrolled and controlled systems are evaluated to determine the control efficacy. It is shown by numerical results that the proposed stochastic optimal control method is more effective and efficient than other optimal control methods.

关键词： stochastic optimal control hysteretic systems random vibration stochastic averaging

ON MULTIpLE pOSITIVE SOLUTIONS FOr A NONLINEAr ELLIpTIC prOBLEM IN r^N

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 2000年第3期21卷 351-358页

作者： YANG HAITAO(department of Mathematics, zhejiang university, hangzhou 310027, china.) WU SHAOpING(department of Mathematics, zhejiang university, hangzhou 310027, china.) department of Mathematics Zhejiang University Hangzhou 310027 China

By making use of Variational method, the authors obtain some results about existence of multiple positive solutions and their asymptotic behavior as the parameter →＋∞ for a semilinear elliptic problem in rN.

关键词： Critical point Asymptotic behavior Concentration

NUMErICAL CALCULATION OF DILUTE GAS-pArTICLE FLOWS IN A CYLINDrICAL CONTAINEr WITH A rOTATING COVEr

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 1990年第3期2卷 52-62页

作者： Ding Xue-dong Shanghai university of Technology,Shanghai Institute of Applied Mathematics And mechanics,Shanghai 200072,p.r.china Xu Xue-zi zhejiang university,hangzhou 310027,p.r.china

A new computing technique is described for the solution'of dilute gas-particle fluid flow *** com- mon SIMpLE method is used for the calculation of the gas phase,but for the calculation of the particle phase the MacCormack method(80 style)is *** the technique for gas-particle flows in a rotating cylindrical con- tainer,the field distributions of both phases are *** important parameter Sk(Stokes number)is taken re- spectively as 0.01,0.1 and *** results show the influence of Sk on the *** collisions between particles and the side wall of the container are predicted when Sk=1.

关键词： Flow NUMErICAL CALCULATION OF DILUTE GAS-pArTICLE FLOWS IN A CYLINDrICAL CONTAINEr WITH A rOTATING COVEr GAS

Derivation of Martin-Hou Equation of State from Hard-particle perturbation Theory

在线全文

学校读者我要写书评

暂无评论

Chemical research in Chinese Universities 2000年第1期16卷 49-56页

作者： ZHANG Bing-jian (department of Chemistry, zhejiang university, hangzhou 310027, p. r. china) HOU Yu-chun (department of Chemical Engineering, zhejiang university, hangzhou 310027, p. r. china) zhejiang Univ Dept Chem Hangzhou 310027 Peoples R China zhejiang Univ Dept Chem Engn Hangzhou 310027 Peoples R China

In this paper, the Martin-Hou equation of state is derived by using a power series representation of radial distribution function and an analytic representation of multi-section potential based on the Barker-Henderson hard-particle perturbation theory including high-order terms. In the derivation, a theoretical form of Martin-Hou equation was obtained. It had a similar form and the same capability to predict p-V-T properties as the Martin-Hou equation and no additional data were required for evaluating the constants. The characteristic constants of the theoretical expression have certain relationships with the molecular parameters.

关键词： perturbation theory Martin-Hou equation of state Theoretical expression p-V-T properties Molecular parameter

K-Functional, Weighted Moduli of Smoothness, and Best Weighted polynomial Approximation on a Simplex

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 1999年第3期15卷 395-403,405-406页

作者： Song Li department of Mathematics, zhejiang university, hangzhou 310027, p. r. china department of Mathematics Zhejiang University Hangzhou P. R. China

An inverse theorem for the best weighted polynomial approximation of a function in Lwαp（S） is established. We also investigate Besov spaces generated by Freud weight and their connection with algebraic polynomial a... 详细信息

An inverse theorem for the best weighted polynomial approximation of a function in Lwαp>pp>（S） is established. We also investigate Besov spaces generated by Freud weight and their connection with algebraic polynomial approximation in Lp（r）wλ, where wα is a Jacobi-type weight on S, 0p≤∞, S is a simplex and Wλ is a Freud weight. For Ditzian-Totik K-functionals on Lp（S）, 1≤p≤∞, we obtain a new equivalence expression.

关键词： Weighted moduli of smoothness K-functional Best weighted polynomial approximation Simplex

Mean size formula of wavelet subdivision tree on Heisenberg group

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics(A Journal of Chinese Universities) 2008年第3期23卷 303-312页

作者： wang Guo-mao department of Mathematics,zhejiang university,hangzhou 310027,china department of Mathematics,hangzhou Dianzi university,hangzhou 310018,china. department of Mathematics Zhejiang University Hangzhou 310027 China department of Mathematics Hangzhou Dianzi University Hangzhou 310018 China

The purpose of this paper is to investigate the mean size formula of wavelet packets （wavelet subdivision tree） on Heisenberg group. The formula is given in terms of the p-norm joint spectral radius. The vector refinement equations on Heisenberg group and the subdivision tree on the Heisenberg group are discussed. The mean size formula of wavelet packets can be used to describe the asymptotic behavior of norm of the subdivision tree.

关键词： Heisenberg group wavelet packets subdivision tree joint spectral radius stability

The G Class of Functions and Its Applications

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2000年第3期16卷 455-468页

作者： Shenghong Li department of Mathematics,zhejiang university,hangzhou,310027,p.r.chinaXiangao Liu department of Mathematics,Fudan university,Shanghai,200433,p.r.china department of Mathematics Zhejiang University Hangzhou 310027 P. R. China department of Mathematics Fudan University Shanghai 200433 P. R. China

In this paper,we introduce the concept of the G class of functions of the parabolic class, and show the Hlder continuity of the G class of *** introduction *** concept contributes to the proof of the regularity and ex... 详细信息

关键词： parabolic equation regularity and existence G class of functions