检索结果-南通市图书馆

Steady States of Some Models for Van derWaals Fluids

在线全文

学校读者我要写书评

暂无评论

Communications in Nonlinear Science and Numerical Simulation 1998年第3期3卷 163-167页

作者： Shaoqiang TANG(department of mechanics and engineering Science, Peking {3., Beijing 100871,China) department of mechanics and engineering Science Peking University Beijing 100871 China

We study the steady states of some models for van der Waals fluid. Inparticular, for a mass viscosity model, we show that there is no "cavitation’ wave. Wealso consider the closed orbits, heterocliaic orbits, and the... 详细信息

关键词： steady state phase transition mixed-type problem

Guided wave propagation in multilayered piezoelectric structures

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) 2009年第7期52卷 1094-1104页

作者： GUO YongQiang1, CHEN WeiQiu2,3.& ZHANG YongLiang4 1 Key Laboratory of mechanics on Disaster and Environment in Western China, Ministry of Education, and School of Civil engineering and mechanics, Lanzhou {3., Lanzhou 73.000, China 2 Key Laboratory of Soft Soils and Geoenvironmental engineering, Ministry of Education, and department of Civil engineering, Zhejiang {3., Hangzhou 3.0058, China 3.department of engineering mechanics, Zhejiang {3., Hangzhou 3.0027, China 4 School of Civil engineering, Lanzhou Jiaotong {3., Lanzhou 73.070, China Key Laboratory of mechanics on Disaster and Environment in Western China Ministry of Education and School of Civil Engineering and Mechanics Lanzhou University Lanzhou China Key Laboratory of Soft Soils and Geoenvironmental engineering Ministry of Education and Department of Civil Engineering Zhejiang University Hangzhou China department of engineering mechanics Zhejiang University Hangzhou China School of Civil engineering Lanzhou Jiaotong University Lanzhou China

A general formulation of the method of the reverberation-ray matrix (MRRM) based on the state space formalism and plane wave expansion technique is presented for the analysis of guided waves in multilayered piezoelectric structures. Each layer of the structure is made of an arbitrarily anisotropic piezoelectric material. Since the state equation of each layer is derived from the three-dimensional theory of linear piezoelectricity, all wave modes are included in the formulation. Within the framework of the MRRM, the phase relation is properly established by excluding exponentially growing functions, while the scattering relation is also appropriately set up by avoiding matrix inversion operation. Consequently, the present MRRM is unconditionally numerically stable and free from computational limitations to the total number of layers, the thickness of individual layers, and the frequency range. Numerical examples are given to illustrate the good performance of the proposed formulation for the analysis of the dispersion characteristic of waves in layered piezoelectric structures.

关键词： multilayered piezoelectric structures the method of reverberation-ray matrix guided waves dispersion characteristic

Comparison study of trapped water in human erythrocytes by EPC and DSC method and its application

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2004年第3期47卷 343-351页

作者： ZHAO Gang1, HE Liqun1, GUO Xiaojie2, LIU Zhong3. LUO Dawei1,3.& GAO Dayong1,3.1. Cryobiomedical engineering Research Institute, department of Thermal Science and Energy engineering, {3. of Science and Technology of China, Hefei 23.027, China 2. Red Cross Blood Center of Hefei, Hefei 23.022, China 3. department of Mechanical engineering, {3. of Kentucky, Lexington, KY 40506-0108, usa Cryobiomedical engineering Research Institute Department of Thermal Science and Energy Engineering University of Science and Technology of China Hefei 230027 China Red Cross Blood Center of Hefel Hefei 230022 China department of Mechanical engineering University of Kentucky Lexington KY 40506-0108 United States

The novel differential scanning calorimetry method for determining trapped water volume of human red blood cell during freezing process has been reexamined. Results show that the final erythrocyte volume is 53. of its isotonic volume after freezing to -40℃. An electronic particle counter (MultisizerTM III, Beckman Coulter Inc., usa) was used to measure cell volume changes in response to hypertonic solution. Using this approach, when extracellular solution was 3.86 mOsm, the equilibrium cell volume was found to be 57% of its isotonic value. Both results indicate that 3.%—40% of intracellular water is trapped and cannot respond to osmotic difference between intra- and extracellular solution. These findings are consistent with the published data: at least 20%—3.% of the isotonic cell water volume is retained within RBCs during freezing. Some applications of the values of trapped water are addressed.

关键词： differential scanning calorimeter/DSC, electronic particle counter/EPC, cell volumetric change, red blood cell/RBC/erythrocyte

new discrete element models for elastoplastic problems

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2009年第5期25卷 629-637页

作者： Ming Cheng Weifu Liu Kaixin Liu LTCS and department of mechanics and Aerospace engineering,College of engineering, Peking university, 100871 Beijing, China LTCS and department of mechanics and Aerospace engineering College of Engineering Peking University Beijing China

The discrete element method （DEM） has attractive features for problems with severe damages, but lack of theoretical basis for continua behavior especially for nonlinear behavior has seriously restricted its application. The present study proposes a new approach to developing the DEM as a general and robust technique for modeling the elastoplastic behavior of solid materials. new types of connective links between elements are proposed, the interelement parameters are theoretically determined based on the principle of energy equivalence and a yield criterion and a flow rule for DEM are given for describing nonlinear behavior of materials. Moreover, a numerical scheme, which can be applied to modeling the behavior of a continuum as well as the transformation from a continuum to a discontinuum, is obtained by introducing a fracture criterion and a contact model into the DEM. The elastoplastic stress wave propagations and the tensile failure process of a steel plate are simulated, and the numerical results agree well with those obtained from the finite element method （FEM） and corresponding experiment, and thus the accuracy and efficiency of the DEM scheme are demonstrated.

关键词： DEM Continuum Plasticity Fracture

LARGE DEFLECTION THEORY OF NANOBEAMS

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2010年第5期23卷 394-399页

作者： Dujuan Zeng Quanshui Zheng 1(department of engineering mechanics,Tsinghua {3.,Beijing 100084,China) department of engineering mechanics Tsinghua University Beijing China

One-dimensional nanostructured materials are often used as beams in many applications such as ultrahigh-frequency resonators and ultrasensitive sensors. Compared with usual macroscopic beams, nanobeams have much higher surface/volume ratios so that their surface energies may play a significant role. Besides, they often bear large deflections due to their typically large slenderness ratios and larger elastic ranges. There is, however, lack of a theory that takes into account of both the above two features owned by nanobeams. In this paper, we present such a theory and give applied examples to show that surface energy and large deflection may individually or jointly have notable effects.

关键词： nanobeam surface energy large deflection

POLARIZED SPECKLE-PHOTOELASTICITY FOR 3.D STRESS ANALYSIS

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 1989年第1期5卷 70-76页

作者： Dai Fulong Fang Jing (department of engineering mechanics,Tsinghua {3.) department of engineering mechanics Tsinghua University China

Combining speckle interferometry with photoelasticity,the absolute retardation fringes in 3.D model are obtained by interference of the polarized rays reflected from the two surfaces of a sandwiched plate inside the *** method can avoid the troubles introduced by Poisson's ratio μ=0.5 and stress-optical constants ratio A/B=-2 of the photoelastic material in a stress-frozenstate,and yield the re- sults which provide necessary supplementary information for the completely-experimental solution of 3.D stress state.A comparison of experimental results with theoretical ones shoves the feasibility of the method proposed in the present paper.

关键词： speckle interferometry absolute retardation fringes in 3.D model

ARNOLDI REDUCTION ALGORITHM FOR LARGE SCALE GYROSCOPIC EIGENVALUE PROBLEM

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 1996年第2期9卷 95-103页

作者： Zheng Zhaochang Ren Gexue, department of engineering mechanics, Tsinghua {3., Beijing 100084 department of engineering mechanics Tsinghua University Beijing 100084

Based on Arnoldi's method, a version of generalized Arnoldi algorithm has been developed for the reduction of gyroscopic eigenvalue problems. By utilizing the skew symmetry of system matrix, a very simple recurrence scheme, named gyroscopic Arnoldi reduction algorithm has been obtained, which is even simpler than the Lanczos algorithm for symmetric eigenvalue problems. The complex number computation is completely avoided. A restart technique is used to enable the reduction algorithm to have iterative characteristics. It has been found that the restart technique is not only effective for the convergence of multiple eigenvalues but it also furnishes the reduction algorithm with a technique to check and compute missed eigenvalues. By combining it with the restart technique, the algorithm is made practical for large-scale gyroscopic eigenvalue problems. Numerical examples are given to demonstrate the effectiveness of the method proposed.

关键词： gyroscopic eigenvalue problem skew symmetry Arnoldi reduction algorithm restart technique

NUMERICAL STUDY OF TURBULENT FLOWS OVER WAVY BOUNDARIES

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 1989年第3期5卷 197-204页

作者： Zhang Zhaoshun Cheng Zhan (department of engineering mechanics,Tsinghua {3.) department of engineering Tsinghua university Tsinghua China

The fully developed túrbulent flows over wavy boundaries are investigated by means of the k-ε *** flow characteristics over rigid wavy walls are in good agreement with the availa- ble experimental *** drag reduction has been found in a 2-dimensional channel with periodi- cal wavy *** energy input from turbulent wind to regular waves is also studied in the paper by the same turbulence model with carefully posed boundary conditions at wind-wave *** agreement has been obtained in the prediction of the growth rates of wind waves as compared with the previous theoretical and numerical results.

关键词： turbulent flows wind wave generation drag reduction

CONSERVATION OF THREE-POINT COMPACT SCHEMES ON SINGLE AND MULTIBLOCK PATCHED GRIDS FOR HYPERBOLIC PROBLEMS

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2003年第3期21卷 383-400页

作者： Zi-niu Wu (department of engineering mechanics, Tsinghua {3., Beijing 100084, China) department of engineering mechanics Tsinghua University 北京 100084

For nonlinear hyperbolic problems, conservation of the numerical scheme is important for convergence to the correct weak solutions. In this paper the conservation of the well-known compact scheme up to fourth order of accuracy on a single and uniform grid is studied, and a conservative interface treatment is derived for compact schemes on patched grids. For a pure initial value problem, the compact scheme is shown to be equivalent to a scheme in the usual conservative form. For the case of a mixed initial boundary value problem, the compact scheme is conservative only if the rounding errors are small enough. For a patched grid interface, a conservative interface condition useful for mesh refinement and for parallel computation is derived and its order of local accuracy is analyzed.

关键词： Conservation Compact scheme Uniform grid Multiblock patched grid.