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Experimental　Investigation　of　the　Nonlinear　Coupling　Strength　of　a　Photorefractive　Crystal

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Chinese Journal of Lasers 1995年第1期B4卷 81-86页

作者： WANG Jiayou LI Xiaochung GUO Siji SHI Sunxiang(department of applied {2.,Xidian university,Xian 710071,china) Xidian Univ Xi'an China

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关键词： photorefractive erystal nonlinear coupling strength

Resistance of Si_2._2. ceramics to oxidation and erosion of molten silica

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中国有色金属学会会刊：英文版 2000年第3期10卷 418-420页

作者： WANG Si qing(王思青) 1, YAN Yu hua(阎玉华) 2.1. department of Materials Engineering and applied Chemistry, National {2. of Defense Technology, changsha 410073, P.R.china 2. Biomaterials Engineering Center, Wuhan {2. of Technology, W 国防科技大学湖南长沙武汉工业大学湖北武汉

Si 2. 2. ceramics was fabricated from powder by hot pressing in N 2.atmosphere. The resistance of the ceramic sample to oxidation and erosion of molten silica was investigated. The bulk density and open porosity of the ceramic sample were measured according to the Archimedes principle in water. Then fracture surface of the sintered body was observed by SEM. The results and analysis indicate that the resistance of Si 2. 2. ceramics to oxidation and erosion of molten silica increases when its density increases and/or its open porosity decreases. Moreover, they also reveal that the oxidation process is an unsteady dispersing process with oxygen as the constant source, and the resistance to erosion of molten silica related to the quantity of grain boundary in unit surface area. The lowest mass gain is 2.4 g/m 2.after oxidizing at 1 000 ℃ for 100 h in air, while the lowest mass loss is 2.9 g/m 2.after 40 h erosion in molten silica.

关键词： silicon oxynitride ceramics chemical stability

Screw dislocations interacting with two asymmetrical interfacial cracks emanating from an elliptical hole

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Chinese physics B 2013年第1期22卷 356-362页

作者：曾鑫方棋洪刘又文 P. H. Wen State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University College of Mechanical and Vehicle Engineering Hunan University School of Engineering and Material Sciences Queen Mary University of London

The interaction between screw dislocations and two asymmetrical interfacial cracks emanating from an elliptic hole under loads at infinity is studied. The closed-form solution is derived for complex potentials. The stress intensity factor and the critical applied stress for the dislocation emission are also calculated. In the limiting cases, well-known results can be obtained from the present solutions. Moreover, new exact solutions for a screw dislocation interacting with some complicated cracks are derived. The results show that the shielding effect increases with the increase in the length of the other cracks and the minor semi axis, but decreases with the increase of dislocation azimuth. The repulsion acting on the dislocation from the other phase and the other crack extend in the horizontal direction, which makes the dislocation emission at the crack tip take place more easily, but the minor semi axis of the elliptical hole extending in the vertical direction makes it more difficult.

关键词： interfacial crack elliptic hole shielding effect dislocation emission

Simulation of nuclei morphologies for binary alloy

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Science china Mathematics 2010年第11期53卷 2927-2936页

作者： LI DaMing1, & ZHANG PingWen2.1department of Mathematics, Shanghai Jiaotong university, Shanghai 2.02.0, {2. 2.ey Lab of Mathematics and applied Mathematics, Center for applied physics and Technology and School of Mathematical Sciences, Peking university, Beijing 100871, {2. department of Mathematics Shanghai Jiaotong University Key Lab of Mathematics and applied Mathematics Center for Applied Physics and Technology and School of Mathematical Sciences Peking University

We study the critical nuclei morphologies of a binary alloy by the string method. The dynamic equation of the string, connecting the metastable phase (liquid) and stable phase (solid), is governed by Helmholtz free energy for the binary alloy system at a given temperature. The stationary string through the critical nucleus (saddle point) is obtained if the relaxation time of the string is su?ciently large. The critical nucleus radius and energy barrier to nucleation of a pure alloy with isotropic interface energy in two and three dimensions are calculated, which are consistent with the classical nucleation theory. The critical nuclei morphologies are sensitive to the anisotropy strength of interface energy and interface thickness of alloy in two and three dimensions. The critical nucleus and energy barrier to nucleation become smaller if the anisotropy strength of the interface energy is increased, which means that it is much easier to form a stable nucleus if the anisotropy of the interface energy is considered.

关键词： nucleation crystal morphology string method

Microwave peak absorption frequency of liquid

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Science china(physics,Mechanics & Astronomy) 2008年第9期51卷 1254-1263页

作者： HAN GuangZe1 & CHEN MingDong2.1 department of physics,South {2. university of Technology,Guangzhou 510640,{2. 2.Guangzhou Auto College,South {2. university of Technology,Guangzhou 510800,{2. department of physics South China University of Technology Guangzhou China Guangzhou Auto College South China University of Technology Guangzhou China

Microwave-assisted extraction is a new effective method which has practical ap-plications in many fields. Microwave heating is one of its physical mechanisms,and it also has the characteristic of selectivity. When the applied microwave fre-quency equals a certain absorption frequency of the material (or specific compo-nent),the material will intensively absorb microwave energy. This is also known as resonant absorption,and the frequency is called the peak absorption frequency which depends on the physical structure of the material. In this work,dynamic hy-drogen bond energy was included in molecular activation energy; with the liquid cell model,the expression of interaction energy between dipolar molecules was derived. The rotational relaxation time was gotten from the Eyring viscosity formula. Then based on the relationship between dielectric dissipation coefficient and re-laxation time,the expression of microwave peak absorption frequency as a func-tion of the material physical structure,rotational inertia and electrical dipole mo-ment of molecules was established. These theoretical formulas were applied to water and benzene,and the calculated results agree fairly well with the experi-mental data. This work can not only deepen the study of the interaction between microwave and material,but also provide a possible guide for the experiment of microwave-assisted extraction.

关键词： microwave-assisted extraction microwave heating relaxation time liquid viscosity peak absorption fre-quency

NUMERICAL SIMULATION AND ANALYSIS ON THE VELOCITY FIELD IN BATH OF A ROUND ELECTRIC CLEANING FURNACE

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Journal of Central South university 1997年第1期9卷 54-57页

作者： Zhou Ping Mei Chi Zhou Shuiliang Wang Qianpu(department of applied {2. and Heat Engineering, Central Southuniversity of Technology, changsha 410083, china) department of applied {2. and Heat Engineering Central South University of Technology Changsha 410083 China

The flowing behavior of liquid slag has an important effect on the heat efficiency, recovery ratio ofvaluable metals and life span of the electric cleaning furnace. The velocity procedure using "κ-ε" model wasdeveloped under the cylindrical coordinate system. The procedure is used to calculate the velocity field ofmolten slag. The forces acting on molten slag were analyzed. The calculating method of electromagnetic forcewas described. The discrete equations, which were solved by using SIMPLE algorithm, were generated bymeans of interlace grids and control volume. The boundary layers near the solid wall were treated as wallfunction. The velocity distribution is obtained. The results show that the velocity of molten slag varies withdifferent horizontal sections. There are six eddies in the surface layer of molten slag. A large circle is formedin the sections below the electrodes, while the longitudinal section includes two large circles around the electrode. The influences of the features of the velocity field on the operation in the electric cleaning furnace arediscussed in detail.

关键词： numerical simulation velocity field electric furnace

A low frequency piezoelectric power harvester using a spiral-shaped bimorph

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Science china(physics,Mechanics & Astronomy) 2006年第6期49卷 649-659页

作者： HU Yuantai1,2.HU Hongping2.& YANG Jiashi3 1. Institute of Mechanics and Sensing Technology,Central South university,changsha 410083,{2. 2. department of Mechanics,Huazhong university of Science and Technology,Wuhan 430074,{2. 3. department of Engineering Mechanics,university of Nebraska,Lincoln,NE 68588-052.,USA Institute of Mechanics and Sensing Technology Central South University Changsha 410083 China

We propose a spiral-shaped piezoelectric bimorph power harvester operating with coupled flexural and extensional vibration modes for applications to low frequency energy sources. A theoretical analysis is performed and the computational results show that the spiral structure has relatively low operating frequency compared to beam power harvesters of the same size. It is found that to optimize the performance of a piezoelectric spiral-shaped harvester careful design is needed.

关键词： spiral-shaped bimorph,piezoelectric harvester,power density.

Recurrence spectra of He atoms in strong external fields

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Science china(physics,Mechanics & Astronomy) 2004年第4期47卷 477-484页

作者： LIN Shenglu1, LI Hongyun1, WANG Dehua2. ZHAO Wenli1 & GAO Feng1 1. department of physics, Shandong Normal {2., Jinan 2.0014, china 2. department of Mathematics and physics, Shandong Institute of Architecture and Engineering, Jinan 2.0014, china department of physics Shandong Normal University Jinan China department of Mathematics and physics Shandong Institute of Architecture and Engineering Jinan China

By employing a model potential including the electron exchange energy, we extend the semiclassical closed orbit theory to study the multielectron atoms. Using special region-splitting consistent and iterative method, we figure out the closed orbits in the corresponding classical system and calculate the recurrence spectra of triplet helium atoms in parallel electric and magnetic fields at scaled energy ε=?0.03,n≈40,n=0. The core-scattering effects have been taken into account, which lead to more peaks in the spectra. It has also been confirmed by means of the direct comparison between the spectral portrait in such a plot and those of hydrogen case. In order to compare the theoretic results with experiment, we investigate the closed orbits and recurrence spectra of helium atoms for the similar exchange potential but applied only by single electric field at scaled energy ε=?2.7 case. The spectra are in good agreement with the experimental observation. We conclude that our model is correct and it is necessary to consider the exchange effect for determining the photoabsorption spectra of multielectron atoms in strong external fields.

关键词： exchange potential, recurrence spectra, semiclassical closed orbit theory, core-scattering.

Long time behavior for damped generalized coupled nonlinear wave equations. Ⅱ.Unbounded domain

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Communications in Nonlinear Science and Numerical Simulation 2001年第2期6卷 107-110页

作者： Shaomei FANG and Boling GUO department of Mathematics, Shaoguan university, Shaoguan 512.05, {2. Graduate School, {2. Academy of Engineering physics, Beijing 100088, {2. Center for Nonlinear Studies, Institute of applied physics and Computational department of Mathematics Shaoguan University Shaoguan 512005 China Graduate School China Academy of Engineering Physics Beijing 100088 China Center for Nonlinear Studies Institute of Applied Physics and Computational mathematics Beijing 100088 China

In this paper, by using a priori estimates in the weighted space, the existence of the global attractor for the damped generalized coupled nonlinear wave equations in an unbounded domain is obtained.

关键词： unbounded domain weighted space attractor

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