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High-temperature oxidation behavior of Al_2._3/TiAl matrix composite in air

science china(Technological sciences) 2009年第5期52卷 1273-1282页

作者： AI TaoTao1,WANG Fen2.& FENG xiaoMing1 1 Department of materials science and Engineering,{2. university of technology,Hanzhong 72.003,china 2.school of materials science and Engineering,shaanxi university of science and technology,xi’an 71002.,china 1. Department of materials science and Engineering Shaanxi University of Technology Hanzhong 723003 China 2. school of materials {2. and Engineering Shaanxi University of Science and Technology Xi’an 710021 China

The oxidation behavior of Al2.3/TiAl in situ composites fabricated by hot-pressing technology was in-vestigated at 900℃ in static *** results indicate that the mass gains of the composites samples decrease gradually with increasing Nb2.5 content and the inert Al2.3 dispersoids effectively increase the oxidation resistance of the *** higher the Al2.3 dispersoids content,the more pro-nounced the *** primary oxidation precesses obey approximately the linear laws,and the cyclic oxidation precesses follow the parabolic *** oxidized sample containing Ti2.lN and TiAl phases in the scales exhibits excellent oxidation *** oxide scale formed after exposure at 900 ℃ for 12. h is multiple-layered,consisting mainly of an outer TiO2.layer,an intermediate Al2.3 layer,and an inner TiO2.Al2.3 mixed *** the outer layer to the inner layer,TiO2.Al2.3 mixed layer presents the transit of Al-rich oxide to Ti-rich oxide mixed *** the substrate,cross-section micrograph shows a relatively loose layer,and micro-and macro-pores remain on this layer,which is a transition layer and transferres from Al2.3+TiO2.scale to *** thickness of oxide layer is about 2. μ*** is also found that continuous protective alumina scales can not be observed on the surface of oxida-tion *** ions diffuse outwardly to form the outer TiO2.layer,while oxygen ions transport inwardly to form the inner TiO2.Al2.3 mixed *** long-time intensive oxidation exposure,the internal Al2.3 scale has a good adhesiveness with the outer TiO2.*** obvious spallation of the oxide scales *** increased oxidation resistance by the presence of in situ Al2.3 particulates is at-tributed to the enhanced alumina-forming tendency and thin and dense scale ***2.3 particu-lates enhance the potential barrier of Ti ions from M/MO interface to O/MO interface,thereby the TiO2.growth rate decreases,which is also beneficial to improve the oxidation resistance.

关键词： Al2.3/TiAl matrix composite oxidation resistance high temperature

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Optimization of thermomechanical processes in Cu-Cr-Zr lead frame alloy using neural networks and genetic algorithms

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science china(Technological sciences) 2005年第5期48卷 510-520页

作者： SU Juanhua1,2. LIU Ping2. DONG Qiming2.& LI Hejun1 1. College of materials science and Engineering, Northwestern Polytechnical {2., xi’an 710072. china 2. College of materials science and Engineering, Henan {2. of science and technology, Luoyang 471003, china 1. College of materials science and Engineering Northwestern Polytechnical University 710072 Xi’an China 2. College of materials science and Engineering Henan University of Science and Technology 471003 Luoyang China

The thermomechanical treatment process is effective in enhancing the properties of the lead frame copper alloy. In this study, an optimal pattern of the thermomechanical processes for Cu-Cr-Zr was investegated using an intelligent control technique consisting of neural networks and genetic algorithms. The input parameters of the artificial neural network (ANN) are the reduction ratio of cold rolling, aging temperature and aging time. The outputs of the ANN model are the two most important properties of hardness and conductivity. Based on the successfully trained ANN model, genetic algorithms (GA) are used to optimize the input parameters of the model and select perfect combinations of thermomechanical processing parameters and properties. The good generalization performance and optimized results of the integrated model are achieved.

关键词： Cu-Cr-Zr alloy, thermomechanical processing optimization, artificial neural network, genetic algorithms.

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Fuzzy Evaluation of Thermal Comfort in Naturally Ventilated Residential Buildings in china

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湖南大学学报（自然科学版） 2009年第S1期36卷 71-74页

作者： WANG Yi1,NIU Tian-cai1,LIU Jia-ping2.xiAO Yong-qiang2.3(1.school of Environmental and Municipal Engineering,xi’an university of Architecture and {2.,xi’an,shaanxi 710055,china 2.school of Architecture,xi’an university of Architecture and {2.,xi’an,shaanxi 710055,china 3.school of Physical Education,xi’an university of Architecture and {2.,xi’an,shaanxi 710055,china) school of Environmental and Municipal Engineering Xi'an University of Architecture and Technology Xi'an 710055 China school of Architecture Xi'an University of Architecture and Technology Xi'an 710055 China school of Physical Education Xi'an University of Architecture and Technology Xi'an 710055 China

In order to assess the differences between the human body thermal sensation in naturally ventilated space and that in air-conditioned space,the fuzzy evaluation model was adopted in the research of thermal sensation in naturally ventilated *** on the questionnaires and field measurements,the membership functions were presented by the statistic of the covering frequency to the fuzzy ***-bulb temperature was taken as the only independent variable for membership *** maximum values of membership grades are all at 0.5 or so,which is a distinction character on thermal comfort of naturally ventilated *** the calculating results of membership grades value to different fuzzy evaluation subsets,the Predicted Mean Vote(PMV)was ***,energy coefficient(Ea)was introduced to calculate the energy consumption,and the prediction methods of residential building energy consumption were also ***,the importance of evaluation model of thermal sense is shown through the energy consumption prediction in a specific residential building.

关键词： natural ventilated space thermal sensation fuzzy evaluation membership functions

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Refractive index changes induced by sheet beams with various intensity distributions in LiNbO_(3):Fe crystal

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science china(Physics,Mechanics & Astronomy) 2005年第4期48卷 399-412页

作者： ZHANG Peng1, ZHAO Jianlin1, XU Honglai1, SUN Yidong2. YANG Dexing1 & WANG Meirong1 1. Institute of Optical Information science and technology, {2. of science, Northwestern Polytechnical university, xi’an 710072. china 2. {2. of science, xi’an Jiaotong university, xi’an 710049, china 1. Institute of Optical Information science and Technology School of Science Northwestern Polytechnical University 710072 Xi’an China 2. school of science Xi’an Jiaotong University 710049 Xi’an China

According to the Kukhtarev equations and a simplified model based on the photovoltaic charge carriers transport mechanism, the distributions of the index changes (DICs) in LiNbO3:Fe crystals induced by sheet beams with various intensity profiles are theoretically analyzed. The numerically simulated results coincide with the analytic expressions deduced from the simplified model. The DICs in a LiNbO3:Fe crystal induced by sheet beams with rectangular, Gaussian and square law profiles are measured by using the interferometric method. By employing the analytic expressions, the experimental data points are well fitted. By utilizing the angular spectrum theory and the ray equation, the uniformities of the intensity profiles of the writing beams along the propagation directions and the influences of the self-defocusing effect of the crystal are numerically simulated, respectively. The results show that the experimental results are reliable. The numerically simulated method and the analytic expressions can be both employed to predict the DICs induced by sheet beams with various light intensity profiles. Furthermore, utilizing writing beams with proper intensity profiles, any desired index distributions could be obtained.

关键词： LiNbO3:Fe crystal, light intensity profile, distribution of refractive index changes, sheet beam.

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Surface Nanocrystallization of Magnesium Alloy AZ91D by High-Energy Shot Peening

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Journal of Wuhan university of technology({2. science) 2009年第4期24卷 515-519页

作者：张津 school of materials {2. & Engineering University of Science and Technology Beijing College of materials science & Engineering Chongqing University of Technology

High-energy shot peening （HESP）, a method to produce severe plastic deformation by high velocity flying balls, was applied on die cast magnesium alloy AZ91D. Effects of surface nanocrystallization by HESP and heat treatment at different temperatures were investigated. The mi- crostructure evolution was conducted using X-ray diffraction （XRD） and field emission scanning electronic microscopy （FESEM）. The hardness was measured by microhardness tester. The experimental results show that surface nanocrystrallization of AZ91D obtained by HESP would lead to the increase of microhardness. Low temperature heated at 100℃ for 1 h do not change the property obviously. However, both the microstructure and microhardness vary greatly after heat treatment at 400℃ for 1 h.

关键词： AZ91 D surface nanocrystallization HESP microhardnss corrosion resistance

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Crystal structures and electronic properties of BaC_2.isomers by theoretical study based on DFT

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science china Chemistry 2008年第6期51卷 545-550页

作者： FENG Jing1,xiAO Bing2.& CHEN JingChao1 1 Key Laboratory of Advanced materials of Precious-Nonferrous Metals,Education Ministry of china,and Key Lab of Advanced materials of Yunnan Province,Kunming university of science and technology,Kunming 650093,china 2.school of materials science and Engineering,xi’an Jiaotong university,xi’an 710049,china 1. Key Laboratory of Advanced materials of Precious-Nonferrous Metals Education Ministry of China Kunming China 3. Key Lab of Advanced materials of Yunnan Province Kunming University of Science and Technology Kunming 650093 China 2. school of materials {2. and Engineering Xi’an Jiaotong University Xi’an 710049 China

Band structures and electronic properties of two BaC2.isomers were calculated by using density func-tional theory(DFT) *** ionic bond features are all typical between cation(Ba) and anion clusters(C2. in both structures of the ***,a much stronger covalent bond exists in anion clusters which can be seen by inspecting the electron distribution contour that has a dull bell like shape between two carbon *** shortest distance between Ba2. and C2.? and the bond length in anion clusters are different in these isomers of BaC2.which are 0.2.45 nm and 0.1185 nm for the structure with the I4/mmm space group and 0.2.44 and 0.1136 nm with the C2.c type,*** structures were clarified by combining the DOS to indicate the ionic bonding features more *** analysis provided further evidence on these *** calculation results reveal that the transition temperature of these two polymorphs of BaC2.locates near 132.K,which is consistent with the recent experimental results.

关键词： functional materials metal diaries phase transition electron density first principle calculation orbital bonding state

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A new calculation method for the number of radial slots of a Terfenol rod

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science china(Technological sciences) 2009年第2期52卷 336-338页

作者： HE xiPing1 & ZHANG Pin2.1 Applied Acoustics Institute, shaanxi Normal university, xi’an 710062. {2. 2.school of science, xi’an university of Architecture and technology, xi’an 710055, {2. 1. Applied Acoustics Institute Shaanxi Normal University Xi’an 710062 China 2. school of science Xi’an University of Architecture and Technology Xi’an 710055 China

Terfenol is an ideal choice for medium to high power low frequency sonar. It can offer the transducer designer higher strain, higher power density, but the designer must be aware of the eddy current. To enhance efficiency of the barrel-stave transducer powered by a Terfenol rod, radial slots rather than laminations were used to control eddy currents in the Terfenol drive rod, and the effectiveness and the number of these slots were studied experimentally and calculated by finite element modeling. Based on the characteristic of vortex path, a new simple geometrical method to calculate the number of the radial slots of a Terfenol rod at the operating frequency is put forward in this paper. Moreover, the calculated results are in good agreement with those of using the finite element method (FEM) for the slotted Terfenol rod given by the literature. The method will save much cost to design Terfenol rod transducers.

关键词： Terfenol-D rod eddy current losses limit operating frequency

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Melt-spun Al_(70-X)Si_(30)Mn_X (X=0,3,5,7,10) anode in lithium-ion batteries

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science china(Technological sciences) 2009年第8期52卷 2288-2294页

作者： SUN ZhanBo1, LI XuePeng1, WANG xiaoDong1, HU Qing1, ZHAO MingShu1, ZHU YaoMin2. LI Yan2.& SONG xiaoPing1 1 school of science, State Key Laboratory for Mechanical Behavior of {2., xi’an Jiaotong university, xi’an 710049, china 2.school of {2. science and Engineering, Henan university of science and technology, Luoyang 471003, china 1. school of science State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong University Xi’an 710049 China 2. school of materials {2. and Engineering Henan University of Science and Technology Luoyang 471003 China

Al70-XSi30MnX (X=0, 3, 5, 7, 10, mol%) ribbons were prepared by melt spinning. A supersaturated solid solution of Si and Mn in fcc Al and some microstructures consisting of nano grains were obtained. Some alloys with nano-sized grains exhibited high discharge capacities and favorable cycle properties. The capacity of more than 400 mAh/g could be obtained in melt-spun Al67Si30Mn3 alloy after 2. cycles and more than 300 mAh/g after 40 cycles. Li/Si and Li/Al compounds in the anodes of pure Al and pure Si were not detected in Al-Si-Mn alloys inserted by Li. It is considered that the formation of the supersaturated solid solution and refinement of microstructures have prevented the alloys from the forming the compounds with superfluous Li. As a result, the electrochemical properties have been improved.

关键词： Al-Si-Mn alloy melt spinning microstructure electrochemical property

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Early Age Compressive Strength of Pastes by Electrical Resistivity Method and Maturity Method

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Journal of Wuhan university of technology({2. science) 2011年第5期26卷 983-989页

作者：肖莲珍 school of materials {2. and Engineering Wuhan Institute of Technology

The compressive strength development of Portland cement pastes was investigated by the electrical resistivity method and the maturity *** experiments were carried out on the cement pastes with different water-cement ratios at different curing *** results show that the application of the maturity method has limitation to obtain the *** is found that both of the compressive strength and the electrical resistivity follow hyperbolic trend for all the *** hyperbolic equation of each mix is obtained to estimate the ultimate resistivity value which can probably be *** relationship between electrical resistivity and compressive strength of the cement pastes is established based on the test results and interpreted by the empirical Archie equation and a strength-porosity *** relationship between the electrical resistivity after temperature correction and the compressive strength was linear and independent of curing temperature and water-cement ratio.

关键词： electrical resistivity cement hydration compressive strength maturity method

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Structure and kinematic analysis of a novel 2.DOF translational parallel robot

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Progress in Natural science:materials International 2007年第10期17卷 1213-1219页

作者： Chen Tao1, Wu Chao2.and Liu xinjun2.1. school of Application science and {2., Harbin university of science and {2., Harbin 150080, china 2. Department of Precision Instruments, Tsinghua university, Beijing 100084, china) school of Application science and {2. Harbin University of Science and Technology Harbin 150080 China Department of Precision Instruments Tsinghua University Beijing 100084 China

This paper addresses the analysis of a novel parallel robot with 2.translational degrees of freedom (DOFs). The robot can position a rigid body in a plane with constant orientation. The kinematic structure of the robot is first described in detail. Some kinematic problems, such as the inverse and forward kinematics, velocity, and singularity are then analyzed. The working and assembly modes are discussed. Since it is the most important index to design a robot, the workspace of the robot is studied systematically in this paper. Based on the analysis of reachable workspace and singularity, a kind of workspace concept characterizing the region that the end-effector of the robot can reach in practice is defined. The results of this paper will be very useful for the design and application of the robot.

关键词： parallel robot degree of freedom kinematics workspace.

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