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Refinement Role of Electromagnetic Stirring and Calcium in AZ91 Magnesium Alloy

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Journal of wuhan university of technology(Materials Science Edition) 2008年第2期23卷 194-197页

作者： HAN Hui LIU Shengfa KANG Liugen LIU Linyan (School of Materials Science and Engineering,wuhan university of technology,wuhan 43.070,china) School of Materials Science and Engineering Wuhan University of Technology Wuhan 430070 China

Effects of calcium addition and electromagnetic stirring on the microstructure of AZ91 magnesium alloy and refinement mechanism were *** results show that calcium addition ranging from 0.1wt% to 0.3.wt% does not lead to formation of any new phases but cause the refinement of as- cast ***,combined calcium alloying and electromagnetic stirring significantly decrease the grain size,change the morphologies of theβ-Mg17Al12phases,and reduce their volume *** minimum grain size of AZ91 alloy is obtained in the case of the addition of 0.2 wt%Ca with exciting voltage of 100 *** microstructural refinement is attributed to the increase of the degree of undercooling and nucleation temperature of primaryα-Mg phases on the basis of DTA analysis results.

关键词： AZ91 magnesium alloy electromagnetic stirring calcium microstructural refinement

AN IMPLICIT SCHEME FOR INCOMPRESSIBLE LBGK MODEL

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Journal of Hydrodynamics 2005年第3期17卷 330-337页

作者： DURui SHIBao-chang WANGGuang-chao LIUHong-juan DepartmentofMathematics HuazhongUniversityofScienceandTechnologyWuhan430074China DepartmentofMathematics HuazhongUniversityofScienceandStateKeyLaboratoryofCoalCombustionHuazhongUniversity430074China／／TechnologyWuhan430074ChinaofScienceandTechnologyWuhan

In this paper, an implicit scheme (also called the θ method) was proposed for the Lattice Bhatager-Gross-Krook (LBGK) model simulating incompressible flows. The new parameter θ made the model more flexible. Through the Chapman-Enskog procedure the impressible Navie-Stokes equations could be recovered with the coupled kinetic viscosity. Boundary conditions were treated briefly and it kept the numerical accuracy of the Lattice Boltzmann Method (LBM). The two-dimensional Poiseuille flow was simulated with different values of the parameters. It is found that the numerical accuracy and stability of the implicit scheme can be improved if some adaptable parameters are chosen.

关键词： Lattice Boltzmann Method (LBM) implicit scheme θ-Lattice Bhatager-Gross-Krook (LBGK) model Poiseuille flow

Photoluminescence of ZnO Nanorods Grown by Hydrothermal Method on Si Substrate

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wuhan university Journal of Natural Sciences 2009年第5期14卷 415-418页

作者： HU Ming,ZHANG Xia,MENG Xianquan School of physics and technology,wuhan {3.,wuhan 4.0072.Hubei,china School of physics and technology Wuhan University Wuhan 430072 Hubei China

ZnO nanorods were grown on Si substrate by hydrothermal method under various reaction time （12, 24, and 3. h）, Zn^2＋ concentrations （0.01, 0.02, and 0.05 mol/L） and reaction temperatures （70-95 ~C）. Their photoluminescence （PL） tests were taken at room temperature. Nanorods grown under longer reaction times or higher temperatures can emit stronger UV light and depressed green light, suggesting better crystallization of ZnO nanorods. Higher Zn^2＋ concentration results in stronger green band emitting, whereas the UV peak is depressed with the Zn^2＋ concentration over 0.02 mol/L. This indicates that excessive interstitial Zn defects may be introduced into the nanorods in Zn-rich environment.

关键词： ZnO nanorods hydrothermal method photoluminescence

D-CONVERGENCE AND STABILITY OF A CLASS OF LINEAR MULTISTEP METHODS FOR NONLINEAR DDES

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Journal of Computational Mathematics 2000年第2期18卷 199-206页

作者： Cheng-jian Zhang Xiao-xin Liao (Department of Mathematics, Huazhong university of Science and technology, wuhan 43.074, {3.) 华中科技大学湖北武汉 430074

Presents information on a study which dealt with the error behavior and the stability analysis of a class of linear multistep methods with the Lagrangian interpolation as applied to the nonlinear delay differential eq... 详细信息

关键词： D-convergence stability multistep methods nonlinear DDEs

Point-Tree Structure Genetic Programming Method for Discontinuous Function's Regression

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wuhan university Journal of Natural Sciences 2003年第S1期8卷 323-326页

作者： Xiong Sheng-wu, Wang Wei-wuSchool of Computer Science and technology, wuhan university of technology, {3. 43.070, Hubei. china wuhan university of technology School of Computer Science and Technology Wuhan Hubei China (GRID:grid.162110.5) (ISNI:***)

A new point-tree data structure genetic programming (PTGP) method is proposed. For the discontinuous function regression problem, the proposed method is able to identify both the function structure and discontinuities points simultaneously. It is also easy to be used to solve the continuous function's regression problems. The numerical experiment results demonstrate that the point-tree GP is an efficient alternative way to the complex function identification problems.

关键词： genetic programming symbolic regression point-tree structure

The Preparation and Characterization of Amorphous SiCN Thin Films

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wuhan university Journal of Natural Sciences 2001年第3期6卷 665-669页

作者： Li Jin chai, Lu Xian feng, Zhang Zi hong, Guo Huai xi, Ye Ming sheng School of physics and technology, wuhan university,{3. wuhan university School of Physics and Technology Wuhan China (GRID:grid.49470.3e) (ISNI:***)

Radio Frequency plasma enhanced Chemical Vapor Deposition (RF CVD) using N2, SiH4 and C2H4 as the reaction sources was used to prepare amorphous ternary Si x C y N z thin films. The chemical states of the C, Si and N atoms in the films were characterized by X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared Spectroscopy (FTIR). The refractive indexn, extinction coefficientk and optical band gapE opt of the thin films were investigated by UV-visible spectrophotometer and spectroscopic ellipsometer. The results show that a complex chemical bonding network rather than a simple mixture of Si3.4, SiC, CN x and a-C etc., may exist in the ternary thin films. Then's of the films are within the range of 1. 90–2. 45, andE opt's of all samples are within the range of 2. 71–2. 86 eV.

关键词： SiCN thin films RF CVD synthesis optical properties X ray photoelectron spectroscopy (XPS) FTIR

Spiral waves in CIMA model and its LBGK simulation

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Communications in Nonlinear Science and Numerical Simulation 2001年第2期6卷 68-73页

作者： Qing LI, Chuguang ZHENG and Nengchao WANG college of Computer Science and technology, Huazhong university of Science and technology, wuhan 43.074, china e-mail: qingli @ public. *** State Key Laboratory of Coal Combustion, Huazhong university college of Computer Science and technology Huazhong University of Science and Technology Wuhan 430074 China State Key Laboratory of Coal Combustion Huazhong University of Science and Technology Wuhan 430074 China Parallel Computation Institute Huazhong University of Science and Technology Wuhan 430074 China

Two type of structures-Turing patterns and spiral waves-are obtained in chloride-iodide-malonic acid (CIMA) reaction-diffusion model by using lattice Bhatnagar-Gross-Krook (LBGK) method.

关键词： lattice Boltzmann method reaction-diffusion Turing patterns spiral waves

ACOUSTIC REFLECTION FROM A BAFFLED ELASTIC/PIEZOELECTRIC PLATE

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Acta Mechanica Solida Sinica 2002年第2期15卷 156-162页

作者： Zhao Hanzhong (Department of Mechanics,Huazhong university of Science and technology,wuhan 43.074,{3.) Department of Mechanics Huazhong Univ. of Sci. and Technol. Wuhan 430074 China

A finite difference/boundary integral procedure to determine theacoustic reflected pressure from a fluid-loaded bi-laminated plate isdescribed. The bi-laminate is composed of a piezoelectric layer andan elastic layer in contact with the fluid, and is held by anacoustically hard baffle. In the numerical model, the fluid pressureat fluid/solid interface is replaced by a continuum of point sourcesweighted by the normal acceleration of the elastic plate, and thegoverning equation system is solved in the solid domain.

关键词： acoustic reflection baffled palte finite difference boundary integral

Long-period Gratings in-situ Sensing for Flow Monitoring in Liquid Composite Molding

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Journal of Materials Science & technology 2005年第2期21卷 234-238页

作者： Yingdan ZHU, Chang WANG, Jihui WANG, Wei HE and Guoqiang GAO State Key Laboratory of Advanced technology for Materials Synthesis and Proceeding, wuhan university of technology, {3. 43.070, china Mat. Synthesis and Proceeding Lab. Wuhan Univ. of Technol. Wuhan 430070 China

Liquid composite moulding (LCM) processes are used to manufacture high quality and complex-shaped composite parts in the automotive, marine, aerospace and civil industries. On-line sensing plays an important role in controlling the quality of the final product in the LCM manufacturing environment. The long-period fiber grating (LPG) technology, a new real-time fiber optic sensor system, was developed to monitor the flow front progression. The sensor operation and characterization under various process conditions were discussed in detail. The experimental results showed that LPG sensors were robust and reliable to detect the arrival of resin at pre-selected locations in structures with low-medium fiber volume fraction; however were limited at different depths in structures with high fiber volume fraction.

关键词： Liquid composite moulding Flow monitoring Long-period grating