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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 {2., beijing Institute of Technology, beijing 100081, china 2. school of Material science and {2., Central South University, Changsha 410083, china 3. school of Material science and {2., beijing University of Aeronautics and Astronautics, beijing 100083, china 1. school of Material science and {2. Beijing Institute of Technology Beijing 100081 China 2. school of Material science and {2. Central South University Changsha 410083 China 3. school of Material science and {2. 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

Theory and techniques of data mining in CGF behavior modeling

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science china(Information sciences) 2011年第4期54卷 717-731页

作者： YIN YunFei 1,2.GONG GuangHong 2.& HAN Liang 2.1 College of computer science,Chongqing University,Chongqing 400044,{2. 2.school of Automation science and Electrical engineering,beijing University of Aeronautics and Astronautics,beijing 100083,{2. 1. College of computer science Chongqing University Chongqing 400044 China2. School of Automation Science and Electrical Engineering Beijing University of Aeronautics and Astronautics Beijing 100083 China

For the large quantity of data,rules and models generated in the course of computer generated forces (CGFs) behavior modeling,the common analytical methods are statistical methods based on the tactical rules,tactical doctrine and empirical ***,from the viewpoint of data mining,we can find many of these analytical methods are also each-and-every different data mining *** this paper,we survey the data mining theory and techniques that have appeared in the course of CGF behavior modeling from the viewpoint of data ***,we redefine and reclassify these theories and techniques according to the research requirements of data mining (the knowledge structure of data mining).We aim to help the CGF investigators to learn the key points and the research methods of the data intelligent processing in the CGF behavior modeling,and thus we can provide the references for the colleagues who are engaged in the research and practice of the CGF behavior modeling by this *** also introduce our ongoing work on the CGF behavior modeling based on data mining.

关键词： CGF CGF behavior modeling data mining theory and techniques

Algorithm of simulation time synchronization over large-scale nodes

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science in china(Series F) 2008年第9期51卷 1239-1255页

作者： ZHAO QinPing1,2.ZHOU Zhong1,2.& Lü Fang1,2.1 State Key Laboratory of Virtual Reality Technology and Systems,Beihang University,beijing 100083,china {2.,Beihang University,beijing 100083,china State Key Laboratory of Virtual Reality Technology and Systems Beihang University Beijing 100083 China school of computer {2. and engineering Beihang University Beijing 100083 China

In distributed simulation, there is no uniform physical clock. And delay cannot be estimated because of jitter. So simulation time synchronization is essential for the event consistency among nodes. This paper investigates time synchronization algorithms over large-scale distributed nodes, analyzes LBTS （lower bound time stamp） computation model described in IEEE HLA standard, and then presents a grouped LBTS model. In fact, there is a default premise for existing algorithms that controi packets must be delivered via reliable transportation. Although, a theorem of time synchronization message＇s reliability is proposed, which proves that only those control messages that constrain time advance need reliability. It breaks out the default premise for reliability. Then multicast is introduced into the transmis- sion of control messages, and algorithm MCTS （multi-node coordination time synchronization） is proposed based on multicast. MCTS not only promotes the time advance efficiency, but also reduces the occupied network bandwidth. Experiment results demonstrate that the algorithm is better than others in both time advance speed and occupied network bandwidth. Its time advance speed is about 50 times per second when there are 1000 nodes, approximately equal to that of similar systems when there are 100 nodes.

关键词： distributed simulation time synchronization multi-node coordination LBTS multicast

The numerical method for three-dimensional impact with friction of multi-rigid-body system

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science china(Physics,Mechanics & Astronomy) 2006年第1期49卷 102-118页

作者： ZHAO Zhen1,2. LIU Caishan2.& CHEN Bin2.1. beijing Institute of Graphic Communication, beijing 102.00, {2. 2. Department of Mechanics & engineering science, Peking University, beijing 100871, {2. beijing Institute of Graphic Communication Beijing 102600 China Department of Mechanics & engineering science Peking University Beijing 100871 China

The differential equations for planar impacts reduce to an algebraic form, and can be easily solved. For three dimensional impacts with friction, there is no closed-form solution, and numerical integration is required due to the swerve behavior of tangential impulse during collisions. The dynamic governing equations in the impact process are built up in impulse space based on the Lagrangian equation in this paper. The coefficient of restitution defined by Poisson is used as the condition of impact termination. A valid nu- merical method for solving three-dimensional frictional impact of multi-rigid body system is established. The singular cases of tangential movement in sticking point are especially noticed and analyzed. Several examples are present to reveal the different kinds of tan- gential movement modes varied with the normal impulse during collision.

关键词： multi-rigid body, impact, friction.

Quality evaluation for air plasma spray thermal barrier coatings with pulsed thermography

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Progress in Natural science:Materials International 2011年第4期21卷 301-306页

作者： Shi-bin ZHAO~1,Cun-lin ZHANG~2.Nai-ming WU~3,Hua-ming WANG~1 1.school of Materials science and {2.,Beihang University,beijing 100191,china 2.Department of Physics,Capital Normal University,beijing 100048,china 3.school of Jet Propulsion,Beihang University,beijing 100191,china [a] school of Materials science and {2. Beihang University Beijing 100191 China [b] Department of Physics Capital Normal University Beijing 100048 China [c] school of Jet Propulsion Beihang University Beijing 100191 China

Pulsed thermography(PT) as a non-contact non-destructive evaluation(NDE) technique was employed to examine as-sprayed air plasma spray(APS) thermal barrier coatings(TBCs) for quality *** and micro-structural characteristics play a vital role in determining the *** this paper,PT logarithmic peak second-derivative method was adopted to measure the thickness of top *** dependent thermal images were used to characterize the microstructure which was confirmed by scanning electron microscope(SEM).The results showed that there was relationship between the temperature distribution of the surface and microstructure change in *** distribution in thermal images and measurement results of thickness were in fairly good agreement with the microstructure *** can be concluded that it was possible to employ these NDE methods as quality evaluation for as-sprayed TBCs.

关键词： thermal barrier coatings(TBCs) non-destructive evaluation(NDE) pulsed thermography microstructure thickness measurement

Nonlinear flutter analysis of stiffened composite panels in super-sonic flow

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science china(Physics,Mechanics & Astronomy) 2010年第2期53卷 336-344页

作者： YUAN KaiHua & QIU ZhiPing school of Aeronautic science and {2.,beijing University of Aeronautics and Astronautics,beijing 100191,china 1. school of Aeronautic science and {2. Beijing University of Aeronautics and Astronautics Beijing 100191 China

The flutter instability of stiffened composite panels subjected to aerodynamic forces in the supersonic flow is investigated. Based on Hamilton's principle,the aeroelastic model of the composite panel is established by using the von Karman large deflection plate theory,piston theory aerodynamics and the quasi-steady thermal stress theory. Then,using the finite element method along with Bogner-Fox-Schmit elements and three-dimensional beam elements,the nonlinear equations of motion are derived. The effect of stiffening scheme on the flutter critical dynamic pressure is demonstrated through the numerical example,and the nonlinear flutter characteristics of stiffened composite panels are also analyzed in the time domain. This will lay the foundation for design of panel structures employed in aerospace vehicles.

关键词： panel flutter piston theory finite element method quasi-steady thermal stress critical dynamic pressure stiffened composite panel

Bio-regeneration of p-complexation desulfurization adsorbents

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science china Chemistry 2005年第6期48卷 538-544页

作者： LI Wangliang1,2. XING Jianmin1, XIONG Xiaochao1,2. SHAN Guobin1,2.& LIU Huizhou1 1. Laboratory of Separation science and engineering, Institute of Process engineering, Chinese Academy of sciences, beijing 100080, china 2. Graduate school of the Chinese Academy of sciences,beijing 100039, china 1. Laboratory of Separation science and engineering Institute of Process Engineering Chinese Academy of Sciences 100080 Beijing China 2. Graduate school of the Chinese Academy of sciences 100039 Beijing China

The coupling of adsorption desulfurization and biodesulfurization is a new approach to produce clean fuels. Sulfur compounds are firstly adsorbed on adsorbents, and then the ad-sorbents are regenerated by microbial conversion. p-Complexation adsorbent, Cu(I)-Y, was ob-tained by ion exchanging Y-type zeolite with Cu2. and then by auto-reduction in helium at 450℃ for 3 h. Dibenzothiophene (DBT) was used as a model compound. The effects of cell concentra-tion, volume of oil phase, the ratio of aqueous phase to adsorbent on DBT desorption by a bac-terium were studied. The amounts of DBT desorbed and 2.HBP produced can be apparently increased with addition of n-octane. BDS activity can be improved by increasing cell concentra-tion and the ratio of water-to-adsorbent. 89% of DBT desorbed from the adsorbents can be converted to 2.HBP within 6 h and almost 100% within 2. h, when the volume ratio of oil-to-water was 1/5 mL/mL, the cell concentration was 60 g·L?1, and the ratio of adsorbent-to-oil was 0.03 g·mL?1. The amount of 2.HBP produced was strongly dependent on the volume ratio of oil-to- water, cell concentration and amount of adsorbent. Adsorption capacity of the regenerated ad-sorbent is 95% that of the fresh one after being desorbed with Pseudomonas delafieldii R-8, washed with n-octane, dried at 100℃ for 2. h and auto-reduced in He.

关键词： adsorption desulfurization p-complexation adsorbents bio-regeneration Pseudomonas delafieldii desorption.

Effect of dendrite arm spacing and the γ' phase size on stress rupture properties of Ni_3Al-base single crystal superalloy IC6SX

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science china(Technological sciences) 2010年第6期53卷 1460-1465页

作者： JIANG LiWu1,LI ShuSuo1,WU MeiLing1 & HAN YaFang1,2.1 school of Materials science and {2.,Beihang University,beijing 100191,china 2.beijing Institute of Aeronautical Materials,beijing 100095,china 1. school of Materials science and {2. Beihang University Beijing 100191 China2. Beijing Institute of Aeronautical Materials Beijing 100095 China

The effect of dendrite arm spacing and the size of γ' phase on stress rupture properties of as-cast Ni3Al-based single crystal superalloy IC6SX was *** has been found that the stress rupture properties were affected by dendrite arm spacing and the size of γ' phase significantly,i.e.,the stress rupture lives of as-cast specimens under the test condition of 1100°C/12. MPa were significantly increased from about 10 h to 31 h with decreasing dendrite arm spacing and the size of γ' phase from 3.0 μm and 1.6 μm to 1.3 μm and 0.8 μm,*** creep cracks generated easily in the brittle Y-NiMo *** the cracks gradually mergered and grew up during creep,and finally led to specimens *** orientated coarsening of γ' phase has been found in the stress ruptured specimens,due to the elements ***,the γ' phase did not form the integrated structure during the short periods of 10-31 h as the creep tests lasted.

关键词： dendrite arm spacing size of γ’ phase Ni3Al-based single crystal stress rupture property

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 {2. and Technology beijing, beijing 100083, china 2. school of Material {2., University of {2. and Technology beijing, beijing 100083, china 3. Central Iron and Steel Research Institute, beijing 100081, china 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 RE2.3 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.