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1.
《中国颗粒学报》2005,3(1):1-1
Hosted by the Institute of Process Engineering, CAS, China, and the Technical University Hamburg- Harburg, Germany, and supported by the Sino-German Science Center in Beijing,the Sino-German Workshop on chemical and physical interactions between particles and fluids is different from any other technical conference: it is discursive and interactive on problems which plague the practitioner and perplex the theoretician, and is exploratory and mutually heuristic in innovative concepts, be that on methodology, design, process or products. 相似文献
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Theodore Yaotsu Wu 《Acta Mechanica Sinica》2011,27(3):309-317
This is a series of studies on Wu’s conjecture and on its resolution to be presented herein. Both are devoted to expound all the comprehensive properties of Cauchy’s function f(z) (z = x + iy) and its integral J[f(z) ] ≡(2πi) -1 C f(t)(t z) -1dt taken along the unit circle as contour C,inside which(the open domain D+) f(z) is regular but has singularities distributed in open domain Doutside C. Resolution is given to the inverse problem that the singularities of f(z) can be determined in analytical form in terms of the values f(t) of f(z) numerically prescribed on C(|t| = 1) ,as so enunciated by Wu’s conjecture. The case of a single singularity is solved using complex algebra and analysis to acquire the solution structure for a standard reference. Multiple singularities are resolved by reducing them to a single one by elimination in principle,for which purpose a general asymptotic method is developed here for resolution to the conjecture by induction,and essential singularities are treated with employing the generalized Hilbert transforms. These new methods are applicable to relevant problems in mathematics,engineering and technology in analogy with resolving the inverse problem presented here. 相似文献
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Comprehensive form of solution for Lamb's dynamic problem expressed by Green's functions* 总被引:1,自引:0,他引:1
By the analysis for the vectors of a wave field in the cylindrical coordinate and Sommerfeld's identity as well as Green's functions of Stokes' solution pertaining the conventional elastic dynamic equation, the results of Green's function in an infinite space of an axisymmetric coordinate are shown in this paper. After employing a supplementary influence field and the boundary conditions in the free surface of a senti-space, the authors obtain the solutions of Green's function for Lamb's dynamic problem. Besides, the vertical displacement uzz and the radial displacement urz can match Lamb's previous results, and the solutions of the linear expansion source u~r and the linear torsional source uee are also given in the paper. The authors reveal that Green's function of Stokes' solution in the semi-space is a comprehensive form of solution expressing the dynamic Lamb's problem for various situations. It may benefit the investigation of deepening and development of Lamb's problems and solution for pertinent dynamic problems conveniently. 相似文献
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Ling Liu Zhengming Huang 《Acta Mechanica Solida Sinica》2014,27(3):234-244
Explicit expressions of Mori-Tanaka's tensor for a transversely isotropic fiber rein- forced UD composite are presented. Closed-form formulae for the effective elastic properties of the composite are obtained. In a 3D sense, the resulting compliance tensor of the composite is symmetric. Nevertheless, the 2D compliance tensor based on a deteriorated Mori-Tanaka's tensor is not symmetric. Nor is the compliance tensor defined upon a deteriorated 2D Eshelby's tensor. The in-plane effective elastic properties given by those three approaches are different. A detailed comparison between the predicted results obtained from those approaches with experimental data available for a number of UD composites is made. 相似文献
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IntroductionEady’smodelisanimportantexampleof 3_dimensionalcontinuouslystratifiledquasi_geostrophicmotion[1].Recently ,someresultsofnonlinearstabilityforEady’smodelwereobtained[2 ,3],wheretheresultofRef.[3 ]istheimprovementofRef.[2 ] ,suchthattheresultisthebestinsomesense[4 ].Inthispaper,theresultofRef.[3 ]isimprovedbyestablishinganenhancedPoincar啨typeintegralinequality .ThenewresultshowsthatthenecessaryandsufficientlinearstabilityconditionforEady’smodelisalsothesu… 相似文献
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The general framework of Poincaré's formalism is used to establish the connection between conservation laws and invariance
properties of Hamilton's function under infinitesimal transformations when these laws and the Hamiltonian are time-dependent.
An example illustrative of the theory is also considered.
The English text was polished by Yunming Chen 相似文献
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Appling Mindlin's theory of thick plates and Hamilton system to propagation of elastic waves under free boundary condition, a solution of the problem was given. Dispersion equations of propagation mode of strip plates were deduced from eigenfunction expansion method. It was compared with the dispersion relation that was gained through solution of thick plate theory proposed by Mindlin. Based on the two kinds of theories, the dispersion curves show great difference in the region of short waves, and the cutoff frequencies are higher in Hamiltonian systems. However, the dispersion curves are almost the same in the region of long waves. 相似文献
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王文治 《应用数学和力学(英文版)》2004,25(2):236-244
Some new Saul‘ yev type asymmetric difference schemes for Burgers’ equation isgiven, by the use of the schemes, a kind of alternating group four points method for solvingnonlinear Burgers‘ equation is constructed here. The basic idea of the method is that thegrid points on the same time level is divided into a number of groups, the differenceequations of each group can be solved independently, hence the method with intrinsicparallelism can be used directly on parallel computer. The method is unconditionally stableby analysis of linearization procedure. The numerical experiments show that the method has good stability and accuracy. 相似文献
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Xiaojing Zheng Li Qiao 《Acta Mechanica Solida Sinica》2009,22(6):511-523
As an important component of nanodevices and nanomachine constructions, the mechanical performance of nanowires (NWs) has been a subject of intense research efforts due to gaining relevance in controlling functionality of nanoelectromechanical systems (NEMS); meanwhile, one of the characteristics of the NEMS is the dependence of the functionality of the systems upon the applied electric field. The study of the electric effects on the Young's modulus of nanostructures is of certain usefulness in the design of NEMS and the precise measurement of mechanical properties of one-dimensional nanostructures. This paper reviews the origin of the size-dependence of the elastic property of NWs and the factors influencing the discrepancies and inconsistencies in the measured values of the Young's modulus for the NW, besides the surface effects, nonlinear effects, the electromechanical coupling effects as a possible effect responsible for the differences in quantitative and qualitative performance of the measured Young's modulus for the NWs versus the diameter are clarified. 相似文献
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By using the fundamental equations of axisymmetric shallow shells of revolution, the nonlinear bending of a shallow corrugated shell with taper under arbitrary load has been investigated. The nonlinear boundary value problem of the corrugated shell was reduced to the nonlinear integral equations by using the method of Green's function. To solve the integral equations, expansion method was used to obtain Green's function. Then the integral equations were reduced to the form with degenerate core by expanding Green's function as series of characteristic function. Therefore, the integral equations become nonlinear algebraic equations. Newton' s iterative method was utilized to solve the nonlinear algebraic equations. To guarantee the convergence of the iterative method, deflection at center was taken as control parameter. Corresponding loads were obtained by increasing deflection one by one. As a numerical example,elastic characteristic of shallow corrugated shells with spherical taper was studied.Calculation results show that characteristic of corrugated shells changes remarkably. The snapping instability which is analogous to shallow spherical shells occurs with increasing load if the taper is relatively large. The solution is close to the experimental results. 相似文献
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A version of Hill's lemma for Cosserat continuum 总被引:4,自引:0,他引:4
On the basis of Hill's lemma for classical Cauchy continuum, a version of Hill's lemma for micro-macro homogenization modeling of heterogeneous Cosserat continuum is presented in the flame of average-field theory. The admissible boundary conditions required to prescribe on the representative volume element for the modeling are extracted and discussed to ensure the satisfaction of Hill-Mandel energy condition and the first-order average field theory. 相似文献
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Wang Xu 《Acta Mechanica Solida Sinica》2005,18(4):302-306
Quasicrystals have additional phason degrees of freedom not found in conventional crystals. In this paper, we present an exact solution for time-harmonic dynamic Green's function of one-dimensional hexagonal quasicrystals with the Laue classes 6/mh and 6/mhmm. Through the introduction of two new functions φ and ψ, the original problem is reduced to the determination of Green's functions for two independent Helmholtz equations. The explicit expressions of displacement and stress fields are presented and their asymptotic behaviors are discussed. The static Green's function can be obtained by letting the circular frequency approach zero. 相似文献
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肖海滨 《应用数学和力学(英文版)》2007,28(4):461-470
Consider a class of Ivlev's type predator-prey dynamic systems with prey and predator both having linear density restricts. By using the qualitative methods of ODE, the global stability of positive equilibrium and existence and uniqueness of non-small amplitude stable limit cycle are obtained. Especially under certain conditions, it shows that existence and uniqueness of non-small amplitude stable limit cycle is equivalent to the local un-stability of positive equilibrium and the local stability of positive equilibrium implies its global stability. That is to say, the global dynamic of the system is entirely determined by the local stability of the positive equilibrium. 相似文献
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Linear Rayleigh-Taylor instability analysis of double-shell Kidder's self-similar implosion solution
This paper generalizes the single-shell Kidder's self-similar solution to the double-shell one with a discontinuity in density across the interface. An isentropic implosion model is constructed to study the Rayleigh-Taylor instability for the implosion compression. A Godunov-type method in the Lagrangian coordinates is used to compute the one-dimensional Euler equation with the initial and boundary conditions for the double-shell Kidder's self-similar solution in spherical geometry. Numerical results are obtained to validate the double-shell implosion model. By programming and using the linear perturbation codes, a linear stability analysis on the Rayleigh-Taylor instability for the double-shell isentropic implosion model is performed. It is found that, when the initial perturbation is concentrated much closer to the interface of the two shells, or when the spherical wave number becomes much smaller, the modal radius of the interface grows much faster, i.e., more unstable. In addition, from the spatial point of view for the compressibility effect on the perturbation evolution, the compressibility of the outer shell has a destabilization effect on the Rayleigh-Taylor instability, while the compressibility of the inner shell has a stabilization effect. 相似文献
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等几何分析使用 NURBS 基函数统一表示几何和分析模型, 消除了传统有限元的网格离散误差, 容易构造高阶连续的协调单元. 对于结构分析, 选择合适的几何参数可以得到光滑的应力解, 避免了后置处理的应力磨平. 但是由于 NURBS 基函数不具备插值性, 难以直接施加位移边界条件. 针对这一问题, 提出一种基于 Nitsche 变分原理的边界位移条件“弱”处理方法, 它具有一致稳定的弱形式, 不增加自由度, 方程组对称正定和不会产生病态矩阵等优点. 同时给出方法的稳定性条件, 并通过求解广义特征值问题计算稳定性系数. 最后, 数值算例表明 Nitsche 方法在h细化策略下能获得最优收敛率, 其结果要明显优于在控制顶点处直接施加位移约束.} 相似文献
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MICROCOSMIC BOUND THEOREM OF DAYCY'S LAW AND ITS APPLICATION 总被引:1,自引:0,他引:1
By combining Chapman-Enskog expansion with the BGK approximation to Baltzmann equation and Navier-Stokes equation was obtained. And an expression of Darcy‘ s law was obtained through taking variable average over Navier-Stokes equation on some representative space in porous media, and finally an example was taken to prove its reliability. 相似文献