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Study on H atoms diffusion and adsorption properties of MgH_2-V systems

Science china(Technological Sciences) 2008年第7期51卷 979-988页

作者： ZHOU DianWu1,2, LIU JinShui3 & PENG Ping3 1 State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, hunan university, changsha 410082, china 2 college of mechanical and automatic engineering, hunan university, changsha 410082, china 3 college of Materials Science and engineering, hunan university, changsha 410082, china 1. State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University Changsha 410082 China 2. college of mechanical and automatic engineering Hunan University Changsha 410082 China 3. college of Materials Science and engineering Hunan University Changsha 410082 China

Based on experimental results that VH0.81/MgH2 interface was found during the process of mechanically milling MgH2+5at.%V nanocomposite, H atoms diffusion and adsorption properties of MgH2-V systems have been investigated by using a first-principles plane-wave pseudopotential method based on the density functional theory. The results are as follows. When VH/MgH2 interface is formed due to V alloying MgH2 phase, the vacancy formed by H atoms near VH phase region is more stable than that without V alloying, while vacancy near MgH2 phase region is less stable than that without V alloying. During the process of H atoms diffusion after V alloying, the max migration barrier energy of H atoms in MgH2-V systems is reduced compared with that of MgH2 phase, which means that H atoms diffuse easily. When H diffuses into VH from MgH2 across VH/MgH2 interface, among three substitutions such as the replacement of H for V vacancy, or interstitial site or V atoms, the replacement of H for V vacancy has the strongest diffusion ability, next interstitial site, and finally V atoms site. As far as H adsorbed on different surfaces of VH phase is concerned, physical adsorption is carried out more easily than chemical adsorption, and the behavior of H atoms adsorbed on the surface near VH phase region can be found more easily than that near MgH2 phase region.

关键词： plane-wave pseudopotential theory magnesium hydride diffusion adsorption

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Microstructure and formation mechanism of twins of laths of austenite with high nitrogen

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Science china(Technological Sciences) 2007年第6期50卷 755-764页

作者： WU CuiLan1,2 & LUO ChengPing2 1 Center for High Resolution Electron Microscopy, college of Materials Science and engineering, hunan university, changsha 410082, china 2 college of mechanical engineering, South china university of Technology, Guangzhou 510641, china 1. Center for High Resolution Electron Microscopy College of Materials Science and Engineering Hunan University Changsha 410082 China 2. college of mechanical engineering South China University of Technology Guangzhou 510641 China

The microstructure of composite diffusion layer of the nitrided and chromized 0.2% carbon steel is investigated using TEM and EDS. It is found that laths of austenite with high nitrogen (γ N) precipitate from α-ferrite matrix in the deeper zone of the diffusion layer. These γ N laths are all twins, with their {111} twinning planes parallel to the lath axis, thus forming a characteristic "back-to-back" morphology. There are two types of γN lath. The first is a genuinely {111} twin, and γ N and α keep the accurate K-S relationship, and each γ N and α form a sharp and smooth γ N/α inter- face of {335}γN//{341}α, namely habit plane {335}fcc. The second is a pseudo-twin, with micro-twins {111} or faults formed within the two twin components. Localized lattice deformation (relaxation) seems to have occurred at the interfaces of the second type of γ N due to the formation of micro-twins or faults within the twin components. These micro-twins or faults make the orientation relationship (OR) between each of the γN and the α-matrix deviate from the accurate K-S OR, and the OR between two γ N twin components deviate from the genuine {111} twin relation- ship. In addition, the γ N/α interface of the second type of γ N is not as sharp or smooth as that of the first one.

关键词： austenite containing nitrogen, twins, steel 20, nitriding, composite chromizing

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Evaporative Condensers in Comfortable Air Conditioning System

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湖南大学学报（自然科学版） 2009年第S1期36卷 136-140页

作者： YIN Ying-de1,ZHU Dong-sheng1,DU Gui-mei2,LI Yuan-xi1,SUN He-jing1,LIU Qing-ming1(1.Key Lab of Enhancement Heat Transfer and Energy Conservation,the Ministry of Education,South china university of Technology,Guangzhou,Guangdong 510641,china 2.college of Civil engineering,hunan university,changsha,hunan 410082,china) Key Lab. of Enhancement Heat Transfer and Energy Conservation South China University of Technology Guangzhou 510641 China college of Civil engineering Hunan University Changsha 410082 China

The operating theory of an evaporative condenser was *** difference between an evaporative condensing refrigeration system and a general refrigeration system was *** with the air-cooled and the water-cooled,the virtues of energy-conservation and water-conservation of evaporative condensers were *** questions existing in the application of evaporative condensers were pointed out,the corresponding solving methods were analyzed accordingly,and the development trend of evaporative condensing technique in mechanical refrigeration system field and the applied foreground of evaporative condensers in comfortable air conditioning were prospected.

关键词： evaporative condensers evaporative condensing refrigeration system general refrigeration system comfortable air conditioning system

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The Influence of Some Key Parameters on Fatigue Life of Common Metallic Components

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Journal of Central South university 2000年第3期12卷 159-161页

作者： LIU Yi lun (college of mechanical and Electrical engineering, Central South university, changsha 410083, china) 1. college of mechanical and Electrical engineering Central South University 410083 Changsha China

The effect of key parameters on fatigue life of common metallic components, e.g. steel, aluminium alloy, has been analysed quantitatively. The influential coverage and degree of these parameters have been investigated systematically, some phenomena which can′t be discovered with qualitative analysis method have been revealed, a series of valuable conclusions has been obtained, which would be very beneficial to fatigue resistant design and improvement of anti fatigue ability of metallic components.

关键词： metallic material component fatigue life key parameter effect

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MOTION ANALYSIS AND DESIGN OF ACCUMULATOR FOR HYDRAULIC ROCK DRILL

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中国有色金属学会会刊：英文版 1996年第2期6卷 148-151页

作者： Liu Shixun(college of mechanical and Electrical engineering, Central South university of Technology, changsha 410083) CENT S UNIV TECHNOL COLL MECH & ELECT ENGNCHANGSHA 410083PEOPLES R CHINA

ＭＯＴＩＯＮＡＮＡＬＹＳＩＳＡＮＤＤＥＳＩＧＮＯＦＡＣＣＵＭＵＬＡＴＯＲＦＯＲＨＹＤＲＡＵＬＩＣＲＯＣＫＤＲＩＬＬＬｉｕＳｈｉｘｕｎ（ＣｏｌｌｅｇｅｏｆＭｅｃｈａｎｉｃａｌａｎｄＥｌｅｃｔｒｉｃａｌＥｎｇｉｎｅｅｒｉ... 详细信息

ＭＯＴＩＯＮＡＮＡＬＹＳＩＳＡＮＤＤＥＳＩＧＮＯＦＡＣＣＵＭＵＬＡＴＯＲＦＯＲＨＹＤＲＡＵＬＩＣＲＯＣＫＤＲＩＬＬＬｉｕＳｈｉｘｕｎ（ＣｏｌｌｅｇｅｏｆＭｅｃｈａｎｉｃａｌａｎｄＥｌｅｃｔｒｉｃａｌＥｎｇｉｎｅｅｒｉｎｇ，ＣｅｎｔｒａｌＳｏｕｔｈＵｎ...

关键词： hydraulic accumulator diaphragm service life stretching ratio parameter design,motion analvsis

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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

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Heat transfer analysis for the roller shell under the condition of periodic thermal shock

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Journal of university of Science and Technology Beijing 2003年第6期10卷 44-47页

作者： Lihua Zhan and Xiaoqian Licollege of Electro-mechanical engineering, Central South university, changsha 410083, china college of Electro-mechanical engineering Central South University Changsha 410083 China

According to the actual working conditions of roller shell in the process ofcontinuous roll casting, the Fourier heat transfer law is used to conduct the simulating analysisfor the temperature distribution of the roller shell under the condition of periodic thermal *** temperature variation law inside the roller shell is studied during the process of continuousroll casting, and the steady temperature distributions of the roller shell at different castingvelocities have been obtained when the thermal contact conductance between the roller shell and thecasting strip is considered.

关键词： roller shell thermal contact conductance (TCC) periodic thermal shock

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Calculation and characteristics analysis of blade pitch loads for large scale wind turbines

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Science china(Technological Sciences) 2010年第5期53卷 1356-1363页

作者： DAI JuChuan1,2,HU YanPing1,LIU DeShun1,2 & LONG Xin3 1 School of Electromechanical engineering,hunan university of Science and Technology,Xiangtan 411201,china 2 college of mechanical and Electrical engineering,Central South university,changsha 410083,china 3 Hara XEMC Windpower Co.,Ltd.,Xiangtan 411000,china 1. School of Electromechanical engineering Hunan University of Science and Technology Xiangtan 411201 China2. College of Mechanical and Electrical Engineering Central South University Changsha 410083 China3. Hara XEMC Windpower Co. Ltd. Xiangtan 411000 China

Based on the electric pitch system of large scale horizontal-axis wind turbines,the blade pitch loads coming mainly from centrifugal force,aerodynamic force and gravity are analyzed,and the calculation models for them are established in this *** illustration,a 1.2 MW wind turbine is introduced as a practical sample,and its blade pitch loads from centrifugal force,aerodynamic force and gravity are calculated and analyzed separately and *** research results showed that in the process of rotor rotating 360o,the fluctuation of blade pitch loads is similar to cosine curve when the rotor rotational speed,in-flow wind speed and pitch angle are ***,the amplitude of blade pitch load presents quite a difference at a different pitch *** ways of calculation for blade pitch loads are of the universality,and are helpful for further research of the individual pitch control system.

关键词： blade pitch loads wind turbine individual variable-pitch pitch axis

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A Method for Identification and Compensation of Machining Errors of Digital Gear Tooth Surfaces

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武汉理工大学学报 2006年第S3期28卷 1135-1139页

作者： WANG Fulin~1 YI Chuanyun~2 CHEN Jing~1 YANG Shuzi~2 (1.college of mechanical and Automotive engineering,hunan university,changsha 410082,china, 2.School of mechanical Science and engineering,Huazhong university of Science and Technology,Wuhan 430074,china) college of mechanical and Automotive engineering Hunan UniversityChangsha 410082China School of mechanical Science and engineering Huazhong University of Science and TechnologyWuhan 430074China

In order to generate the digital gear tooth surfaces(DGTS)with high efficiency and high precision,a method for identification and compensation of machining errors is demonstrated in this *** errors are analyzed directly from the real tooth *** topography data of the part are off-line measured in the post-process.A comparison is made between two models:CAD model of DGTS and virtual model of the physical measured *** a matching rule is given to determine these two surfaces in an appropriate *** developed error estimation model creates a point-to-point map of the real surface to the theoretical surface in the normal direction.A“pre-calibration error compensation”strategy is *** processing the results of the first trail cutting,the total compensation error is predicted and an imaginary digital tooth surface is reconstructed. The machining errors in the final manufactured surfaces are minimized by generating this imaginary *** example of ma- chining 2-D DGTS verifies the developed *** research is of important theoretical and practical value to manufacture the DGTS and other digital conjugate surfaces.

关键词： digital gear tooth surfaces(DGTS) machining error topography measurement error analysis error compensation

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EXTRAPOLATING METHOD IN PLOT FOR FATIGUE LIFE PREDICTION OF COMPONENTS

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中国有色金属学会会刊：英文版 1996年第3期6卷 153-156页

作者： Liu Yilun Wang Ailun(college of mechanical and Electrical engineering,Central South university of Technology, changsha 410083) CENT S UNIV TECHNOL COLL MECH & ELECT ENGNCHANGSHA 410083PEOPLES R CHINA

ＥＸＴＲＡＰＯＬＡＴＩＮＧＭＥＴＨＯＤＩＮＰＬＯＴＦＯＲＦＡＴＩＧＵＥＬＩＦＥＰＲＥＤＩＣＴＩＯＮＯＦＣＯＭＰＯＮＥＮＴＳ￥ＬｉｕＹｉｌｕｎ；ＷａｎｇＡｉｌｕｎ（ＣｏｌｌｅｇｅｏｆＭｅｃｈａｎｉｃａｌａｎｄＥｌｅｃｔ... 详细信息

ＥＸＴＲＡＰＯＬＡＴＩＮＧＭＥＴＨＯＤＩＮＰＬＯＴＦＯＲＦＡＴＩＧＵＥＬＩＦＥＰＲＥＤＩＣＴＩＯＮＯＦＣＯＭＰＯＮＥＮＴＳ￥ＬｉｕＹｉｌｕｎ；ＷａｎｇＡｉｌｕｎ（ＣｏｌｌｅｇｅｏｆＭｅｃｈａｎｉｃａｌａｎｄＥｌｅｃｔｒｉｃａｌＥｎｇｉｎｅｅｒｉｎｇ，...

关键词： extrapolation plot fatigue life

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