检索结果-南通市图书馆

Synchrotron Radiation Tomography for Reconstruction of Layer Structures and Internal Defects of Composite Materials

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Lasers 1999年第6期8卷 24-29页

作者： LI Xide (department of engineering {2., Tsinghua university, beijing 100084, china)HU Xiaofang (department of Modern {2. and engineering, university of science and Technology of china, Hefei 2.002., china) HU Yiguan KAN Ya (National Sy 清华大学工程力学系北京 100084 中国科学技术大学近代力学与工程系安徽合肥 230026 中国科学技术大学同步辐射国家实验室安徽合肥 230026 中国科学技术大学同步辐射国家实验室安徽合肥

Synchrotron radiation tomography has been used as a non intrusive technique to study layer structures and internal defects of composite materials with carbon aluminum fibers and boron carbon fibers. A rotatable platform, which is positioned in a vacuum chamber of a beam line, is used to hold specimens and to get multi directional scanning images. The scanning images are recorded on a PMMA film firstly by use of the single exposure method, resampled by a microscopic system, and reconstructed with computerized tomography to yield their three dimensional descriptions. This reconstruction makes it possible to identify different layers and structures of composite materials. Particularly the defects inside composite materials can also be detected and evaluated.

关键词： composite material synchrotron radiation computerized tomography reconstruction nondestructive evaluation

Prediction and Control of both Wrinkle Limit and Fracture Limiton Cylindrical Cup Deep-drawing(Ⅱ)

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 1999年第3期13卷 201-204页

作者： Junxiang Lei Yonglin Kang(department of Mechanical engineering, Yantai {2., Yantai 2.4005, china)(Material science and engineering School, {2. of science and Technology beijing, beijing 100083, china) department of Mechanical engineering Yantai University Yantai 264005 China Material science and engineering School University of Science and Technology Beijing Beijing 100083 China

The prediction and control criterion of both the wrinkle limit and fracture limit on the cylindrical cup deep-drawing are given, and the prediction and control diagram of both the wrinkle limit and fracture limit are also given. The results show that it is suitable for no-flange cylindrical cup deep-drawing, narrow-flange cylindrical cup deep-drawing, wide-flange cylindrical cup deep-drawing/expanding compound forming and rigid punch expanding forming.

关键词： cylindrical cup wrinkle limit fracture limit deep-drawing expanding forming compound forming

The theoretical research of basic function method in incompressible viscous flow and its simulations in three-dimensional aneurysms

在线全文

学校读者我要写书评

暂无评论

science china(Physics,{2. & Astronomy) 2009年第6期52卷 909-918页

作者： SHEN Fang1 & WU WangYi2.1 State Key Laboratory for Space Weather, Center for Space science and Applied Research, Chinese Academy of sciences, {2. 100190, china 2.State Key Laboratory of Turbulence and Complex Systems & department of mechanics and engineering science, peking university, beijing 1.0871. china 1. State Key Laboratory for Space Weather Center for Space Science and Applied Research Chinese Academy of Sciences Beijing 100190 China 2. State Key Laboratory of Turbulence and Complex Systems & department of mechanics and {2. science Peking University Beijing 100871 China

Basic function method is developed to treat the incompressible viscous flow. Artificial compressibility coefficient, the technique of flux splitting method and the combination of central and upwind schemes are applied to construct the basic function scheme of trigonometric function type for solving three-dimensional incompressible Navier-Stokes equations numerically. To prove the method, flows in finite-length-pipe are calculated, the velocity and pressure distribution of which solved by our method quite coincide with the exact solutions of Poiseuille flow except in the areas of entrance and exit. After the method is proved elementary, the hemodynamics in two-and three-dimensional aneurysms is researched numerically by using the basic function method of trigonometric function type and unstructured grids generation technique. The distributions of velocity, pressure and shear force in steady flow of aneurysms are calculated, and the influence of the shape of the aneurysms on the hemodynamics is studied.

关键词： basic function unstructured grid aneurysm viscous incompressible flow artificial compressibility flux splitting

Two-dimensional simulation of Poiseuille-Rayleigh-Bénard flows in binary fluids with Soret effect

在线全文

学校读者我要写书评

暂无评论

Progress in Natural science:Materials International 2007年第12期17卷 1389-1396页

作者： Hu Jun1 and Yin Xieyuan2.1. Institute of Applied Physics and Computational Mathematics, beijing 100088, china 2. {2. of Modern mechanics, university of science and Technology of china, Hefei 2.002., china) Institute of Applied Physics and Computational Mathematics Beijing 100088 China department of Modern mechanics University of Science and Technology of China Hefei 230027 China

Poiseuille-Rayleigh-Bénard flows in binary fluids with Soret effect are directly simulated by a mixed finite element method. A temperature perturbation is used as an initial disturbed source for the basic parallel flows. The whole spatio-temporal evolution of the binary fluid flows is exhibited: initially only the disturbed mode with the wavenumber k=π is amplified while others are damped, and continuously the amplified mode grows further and the nonlinear effect becomes important; after a nonlinear evolution transition the flow system evolves finally into a periodic right traveling wave.

关键词： Poiseuille-Rayleigh-Bénard flow Soret effect through-flow.

TEXTURE DETERMINATION OF THIN FILM ZrO_2.BY ELECTRON DIFFRACTION

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 1993年第12期6卷 472-473页

作者： WANG Yinghua Tsinghua university,beijing,{2. department of Materials science and engineering,Tsinghua university,beijing 100084,{2. Tsinghua Univ Beijing China

A method for semi-quantitative determination of thin film texture using electron diffrac- tion is *** texture state of a zirconia thin film with a cubic structure has been determined in this way and is presented as an... 详细信息

关键词： texture thin film electron diffraction ZrO_2

Analysis of Gas Radiative Transfer Using Box Model and Its Comparison with Gray Band Approximation

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal science 2003年第1期12卷 82-88页

作者： Yuying Liu Xinxin ZhangThermal engineering department, {2. of science and Technology beijing, beijing 100083, china Thermal engineering department University of Science and Technology Beijing Beijing China

On the basis of a wide range survey of various models or treatment methods for the calculation of radiative properties of gases, box model, which is similar to the gray band approximation of spectral band model, was applied to evaluate the gas properties in this paper. In order to compare the accuracy of box model with that of gray band approximation of spectral band models, a typical one-dimensional gas radiation problem was analyzed using discrete ordinate method. Comparing with the widely used gray band approximation of narrow band model or exponential wide band model, box model can well evaluate the radiation source term of the radiative problem. It also has the advantages of simplicity and easy to code, so it is practicable and useful for some complex engineering problems.

关键词： gray band approximation spectral band model box model discrete ordinate method.

The Absolute and Convective Secondary Instabilities in the Conduction Regime

在线全文

学校读者我要写书评

暂无评论

Communications in Nonlinear science and Numerical Simulation 1999年第1期4卷 34-38页

作者： Jianjun TAO and Dachun YAN (Dept. of mechanics & engineering {2.s,peking university, beijing 1.0871. china) Dept. of mechanics & engineering {2.s Peking University Beijing 100871 China

Convective and absolute instabilities in the conduction regime of a vertical heated slot are investigated. It is found that in a large range of Prandtl number (0 12. a secondary instability appears with stationary mo... 详细信息

Convective and absolute instabilities in the conduction regime of a vertical heated slot are investigated. It is found that in a large range of Prandtl number (0 2.00) different instability mode has different characteristics: the stationary mode is absolute instability while the traveling wave mode is convective instability. When Pr > 12. a secondary instability appears with stationary mode, and it is proven that even at large Prandtl numbers the stationary mode still exists.

关键词： absolute instability convective instability conduction regime

LARGE DEFLECTION THEORY OF NANOBEAMS

在线全文

同方期刊数据库

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 {2.,Tsinghua university,beijing 100084,china) [a] department of engineering {2. Tsinghua University Beijing 100084 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

One Kind of nth Beltrami Spherical VortexTensor Denotation and its Classification

在线全文

学校读者我要写书评

暂无评论

Communications in Nonlinear science and Numerical Simulation 1999年第4期4卷 3-5页

作者： Yongnian HUANG Xin HU(department of mechanics and {2. science & State Key Laboratory forTurbulence Research, peking university, Beliing 1.0871. china) department of mechanics and {2. science & State Key Laboratory for Turbulence Research Peking University Beijing 100871 China

1OneKindofnibBSVTensorDenotationInaxticle[1],wehadgiventhesolutionsofthebosymmetricnibBeltramiSphericalVortex(BSV)asfollows:Inarticle[2.,wegavethegeneralformofthenibBSV(expressedbythetensordenotation)couldbewrittenas:... 详细信息

关键词： spherical vortex tensor denotation symmetry