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The characteristics of arc beam shaping in hybrid plasma and laser deposition manufacturing

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Science china(Technological Sciences) 2006年第2期49卷 238-247页

作者： ZHANG Hai’ou1, QIAN Yingping1,3. WANG Guilan1 & ZHENG Qiguang2 1. school of Material Science and technology, Huazhong University of Science and technology, Wuhan 43.074, {3. 2. institute of Laser technology and engineering, Huazhong University of Science and technology, Wuhan 43.074, {3. 3. Mechanical engineering College, Hubei University of technology, Wuhan 43.068, {3. 1. school of Material Science and technology Huazhong University of Science and Technology Wuhan 430074 China 3. Mechanical engineering College Hubei University of Technology Wuhan 430068 China 2. institute of Laser technology and engineering Huazhong University of Science and Technology Wuhan 430074 China

As a new direct metal prototyping technology,the hybrid plasma and laser deposition manufacturing (PLDM) is proposed in this paper. In order to figure out the characteristics of plasma arc beam and mould in the PLDM process of high temperature alloy, the high speed CCD camera is used to obtain the picture around the plasma arc. Afterwards the sketch of picture is clearly obtained. And the effect of laser parameter, such as average power, pulse width, pulse repetition frequency and the angle between laser beam and plasma arc beam on the plasma arc appearance, is studied experimentally. The results show that the modality of plasma arc beam is markedly influenced by laser beam. And the improvements of shape precision and surface state of the layer deposited by PLDM are confirmed.

关键词： plasma hybrid laser, direct deposition, plasma arc beam, molding character, high-temperature alloy.

New Solution to Surface Temperature of Casting Slab Measurement Based on Preceded Reflector and Multi-Wavelength

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Journal of Iron and Steel Research International 2012年第8期19卷 12-16页

作者： LIU Jun1, MA Jiao-cheng2, YANG Feng3. XIAO Hui1, RAO Li-min1 (1. school of Nuclear engineering and technology, East {3. institute of technology, Fuzhou 3.4000, Jiangxi, {3. 2. school of Mechanical engineering and Automation, Northeastern University, Shenyang 110004, Liaoning, {3. 3. school of Civil and Environmental engineering, East {3. institute of technology, Fuzhou 3.4000, Jiangxi, {3.) [a] school of Nuclear engineering and technology East China Institute of Technology Fuzhou 344000 Jiangxi China [b] school of Mechanical engineering and Automation Northeastern University Shenyang 110004 Liaoning China [c] school of Civil and Environmental engineering East China Institute of Technology Fuzhou 344000 Jiangxi China

The surface temperature of casting slab is an important parameter in the metallurgy field. Because the surface emissivity is uncertain and also unknown, it is difficult to measure the slab surface temperature accurately. A method based on preceded reflector and multi-wavelength was put forward to deal with the difficulty in surface temperature measurement of casting slab. On the premise of preceded reflector and non-preceded reflector, the method establishes the radiation energy equations and works out the emissivity and temperature in the equations. Also, the multilayer modeling of casting slab surface and multiple reflection-absorption process modeling were built by Monte Carlo method. The temperature measuring method had been applied in the continuous casting field. In order to verify the measured result, the thermal imaging method was adopted when the slab surface emissivity was set by repeated tests. Finally, the measured and verified temperature curves keep a same tendency and the error of the values is lower than 5℃. The comparison result shows that the method can measure temperature accurately.

关键词： casting slab emissivity surface temperature preceded reflector multi-wavelength

The mathematical model of wetting angle of heterogeneous nucleation

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Science china(Technological Sciences) 2004年第4期47卷 391-397页

作者： HUANG Cheng1, SONG Bo1, MAO Jinghong2 & ZHAO Pei3.1. school of Metallurgical and Ecological engineering, University of Science and technology Beijing, Beijing 100083. {3. 2. school of Material Science, University of Science and technology Beijing, Beijing 100083. {3. 3. Central Iron and Steel Research institute, Beijing 100081, {3. 1. school of Metallurgical and Ecological engineering University of Science and Technology Beijing 100083 Beijing China 2. school of Material Science University of Science and Technology Beijing 100083 Beijing China 3. Central Iron and Steel Research institute 100081 Beijing China

The heterogeneous nucleation has been analyzed in terms of the thermodynamic theory, and the mathematical model of wetting angle of heterogeneous nucleation has been developed based on the dynamic requirements of hetero- and homogeneous nucleation. With the wetting angel model, the wetting angles of different catalysts in liquid iron have been calculated. The result shows that the wetting angle of most catalysts is smaller than 40, and the value of f() is far less than 1. The wetting angles of TiN, TiC and RE2O3.are smaller, while the wetting angle of MnO is bigger among the ordinary nucleation catalysts. The wetting angles calculated by this model are in agreement with the results of other research work.

关键词： heterogeneous nucleation, mathematical model, wetting angle, undercooling.

Nonholonomic mapping theory of autoparallel motions in Riemann-Cartan space

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Science china(Physics,Mechanics & Astronomy) 2010年第9期53卷 1707-1715页

作者： GUO YongXin1,LIU Chang2,WANG Yong3.LIU ShiXing1 & CHANG Peng2 1 College of Physics,Liaoning University,Shenyang 11003.,china 2 school of aerospace engineering,Beijing institute of {3.,Beijing 110081,china 3.school of Basic Medical Science,Guangdong Medical College,Dongguan 523.08,china 1. College of Physics Liaoning University Shenyang 110036 China2. School of Aerospace Engineering Beijing Institute of Technology Beijing 110081 China3. School of Basic Medical Science Guangdong Medical College Dongguan 523808 China

The method of nonholonomic mapping is utilized to construct a Riemann-Cartan space embedded into a known Riemann-Cartan space,which includes two special cases that a Weitzenbck space and a Riemann-Cartan space are respectively embedded into a Euclidean space and a Riemann *** means of this mapping theory,the nonholonomic corresponding relation between the autoparallels of two Riemman-Cartan spaces is *** particular,an autoparallel in a Riemann-Cartan space can be mapped into a geodesic line in a Riemann space and an autoparallel in Weitzenbck space be mapped into a geodesic line in Euclidean *** on the Lagrange-d'Alembert principle,the equations of motion for dynamical systems in Riemman-Cartan space should be autoparallel equations of the *** applications,the problem of autoparallel motion of spinless particles,Chaplygin's nonholonomic systems and a rigid body rotating with a fixed point are investigated in space with torsion.

关键词： nonholonomic mapping Riemann-Cartan space connection torsion autoparallel

Analysis for twinning and slip in face-centered cubic crystals under axisymmetric co-deformation

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Science china(Technological Sciences) 2006年第5期49卷 521-536页

作者： CHEN Zhiyong1,2, CAI Hongnian1, ZHANG Xinming2, WANG Fuchi1 & TAN Chengwen1,3.1. school of Material Science and engineering, Beijing institute of {3., Beijing 100081, china 2. school of Material Science and engineering, Central South University, Changsha 410083. china 3. school of Material Science and engineering, Beijing University of Aeronautics and Astronautics, Beijing 100083. china 1. school of Material Science and engineering Beijing Institute of Technology Beijing 100081 China 2. school of Material Science and engineering Central South University Changsha 410083 China 3. school of Material Science and engineering Beijing University of Aeronautics and Astronautics Beijing 100083 China

The maximum work principle of Bishop-Hill was developed to analyze the axisymmetric co-deformation in face-centered cubic crystals (f.c.c.) for twinning on {111} 112 and slip on {111} 110 systems. The influence of ξ , the ratio of critical re- solved shear stress for twinning to slip, on the yield stress states and corresponding active slip or/and twinning systems for orientations in the standard stereographic triangle of cubic crystal was investigated systematically. The Taylor factors and the anisotropy of yield strength for three important orientations [100], [110] and [111] in orientation space were analyzed. It is found that the yield strength asymmetry for the case of axisymmetric de- formation of tension and compression can be explained based on the microscopic theory of crystal plasticity. The concept of orientation factor for twinning ability was proposed and the deformation mechanism map in the orientation space was established for the case of axisymmetric deformation. The deformation texture formation and development of f.c.c. crystals with low stacking fault energy for axisymmetric tension can be explained qualita- tively on the basis of analyzed results.

关键词： twinning slip face-centered cubic crystals axisymmetric co-deformation Bishop-Hill maximum work principle yield strength anisotropy

Effects of binders on the performance of electric double-layer capacitors of carbon nanotube electrodes

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Progress in Natural Science:Materials International 2005年第5期15卷 453-457页

作者： LI Chensha1*, WANG Dazhi1, ZHANG Baoyou2, WANG Xiaofeng1, CAO Maosheng3. and LIANG Ji1(1. Department of Mechanical engineering, Tsinghua University, Beijing 100084, china 2. Center for Analysis and Measurement, Harbin institute of {3., Harbin 150001, china 3. school of Material Science and engineering, Tsinghua University, Beijing 100084, china) Department of Mechanical engineering Tsinghua University Beijing 100084 China Center for Analysis and Measurement Harbin Institute of Technology Harbin 150001 China school of Material Science and engineering Tsinghua University Beijing 100084 China

Polarizable electrodes of electric double layer capacitor (EDLCs) were made from carbon nanotubes. Effects of different binders, which are phenolic resin (PF) and polytetrafluoroethylene (PTFE), on the properties of polarizable electrodes are studied. Results indicate that the microstructure, pore size distribution and specific capacitance of the electrodes with PTFE binder are superior to those electrodes with PF binder after carbonization. The suitable binder (PTFE) for carbon nanotubes electrodes is proposed.

关键词： carbon nanotubes electric double-layer capacitors phenolic resin polytetrafluoroethylene.

Development and Application of High Performance X80 Line Pipe for the 2^(nd) West-East Gas Pipeline

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Journal of Iron and Steel Research International 2011年第S1期18卷 39-48页

作者： LI He-lin 1 , HUO Chun-yong 1 , JI Ling-kang 1, 2 , LI Yang 1, 3.(1. CNPC Tubular Goods Research institute, Xi’an 710065, china 2. . school of Material Science and {3., Xi’an Jiaotong University, Xi’an 710049, china 3. school of Material Science and {3., University of Science and technology Beijing, Beijing 100083. china) CNPC Tubular Goods Res Inst Xian 710065 Peoples R China Xi An Jiao Tong Univ Sch Mat Sci & Engn Xian 710049 Peoples R China Univ Sci & Technol Beijing Sch Mat Sci & Engn Beijing 100083 Peoples R China

It is the development tendency of gas pipeline to improve strength of line pipe and transmission pressure, which is an important symbol of the progress of gas pipeline technology. The 2nd West-East Gas Pipeline (the 2 nd WEGP) is the largest-scale X80 high pressure gas pipeline project in the world. Through the joint development project by Pipeline Company, research institute, and steel company, a series of achievements of technology have been obtained, which makes it possible to apply pressure of 12 MPa and X80 LSAW and HSAW pipe for the 2 nd WEGP. Specifications of X80 steel and pipe have been issued based on API 5L. High performance X80 steel and pipe have been developed and meets the Specification. General design conception of applying HSAW pipe and LSAW pipe on gas transmission trunk line with large diameter and high pressure has been established. Failure control of the 2 nd WEGP has been carried out to avoid failure and reduce the lost which based on analysis of pipeline failure mode. In this paper, research and development of high performance X80 welded pipe, establishment of technical route of joint application of HSAW and LSAW steel pipe and key technology of failure control are emphatically discussed.

关键词： 2 nd WEGP acicular ferrite failure control arrest toughness strain-based design

A formal model of fair exchange protocols

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Science in china(Series F) 2005年第4期48卷 499-512页

作者： QING Sihan1,2,3.& LI Gaicheng1,2,3.1. engineering Research Center for Information Security technology, institute of Software, Chinese Aca- demy of Sciences, Beijing 100080, {3. 2. Beijing Zhongke Ansheng Corporation of Information technology, Beijing 100080, {3. 3. Graduate school of the Chinese Academy of Sciences, Beijing 10003., {3. 1. engineering Research Center for Information Security technology Institute of Software Chinese Academy of Sciences 100080 Beijing China 2. Beijing Zhongke Ansheng Corporation of Information technology 100080 Beijing China 3. Graduate school of the Chinese Academy of Sciences 100039 Beijing China

Based on the study of existing fair exchange protocols, this paper sets up an accurate formal model by stepwise refinement. In the process of refinement an unreliable channel is employed to simulate an attack behavior. The model provides a novel formal definition of exchanged items, and presents the formal goals for fairness, accountability, etc., reflecting the inherent requirements for fair exchange protocols across-the-board. In order to check, prove, and design fair exchange protocols effectively and efficiently, the model puts forward a novel property of abuse-freeness which applies to all fair exchange protocols, gives a formal definition for trust strand of the third party, and presents general criteria of designing a secure and effective fair exchange protocol. Taking a typical fair exchange protocol as an example, this paper presents the analysis steps of fair exchange protocols appealing to our model. An unknown attack is uncovered. The analysis reveals the process of a complete attack, discovering deeper reasons for causing an attack. Finally, we modify the flawed protocol and the revised protocol ensures the desirable properties.

关键词： events local causal relation local temporal relation global relation exchanged item security goals.

Formal Verification under Unknown Constraints

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Wuhan University Journal of Natural Sciences 2005年第1期10卷 43-46页

作者： LI Guang-hui 1,2,3., LI Xiao-wei 2,3.. school of Information engineering, Zhejiang Forestry College, Hangzhou 3.13.0, Zhejiang, china 2. {3. of Computing technology, Chinese Academy of Sciences, Beijing 100080, china 3. Graduate school of the Chinese Academy of Sciences, Beijing 10003., china school of Information engineering Zhejiang Forestry College Hangzhou 311300 Zhejiang China

We present a formal method of verifying designs with unknown constraints (e.g., black boxes) using Boolean satisfiability (SAT). This method is based on a new encoding scheme of unknown constraints, and solves the corresponding conjunctive normal form (CNF) ***,this method can avoid the potential memory explosion, which the binary decision diagram (BDD) based techniques maybe suffer from, thus it has the capacity of verifying large designs. Experimental results demonstrate the efficiency and feasibility of the proposed method.

关键词： formal verification unknown constraints black box Boolean satisfiability Boolean comparison