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

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 {2. 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 {2. and engineering, Beijing university of Aeronautics and Astronautics, Beijing 100083, china 1. school of material {2. 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 {2. 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

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Relaxed resource advance reservation policy in grid computing

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The Journal of china Universities of Posts and Telecommunications 2009年第2期16卷 108-113页

作者： XIAO Peng HU Zhi-gang school of Information science and {2.,central south university,changsha 410083,china [a]school of Information science and {2. central south {2. changsha 410083 china

The advance reservation technique has been widely applied in many grid systems to provide end-to-end quality of service （QoS）. However, it will result in low resource utilization rate and high rejection rate when the reservation rate is high. To mitigate these negative effects brought about by advance reservation, a relaxed advance reservation policy is proposed, which allows accepting new reservation requests that overlap the existing reservations under certain conditions. Both the benefits and the risks of the proposed policy are presented theoretically. The experimental results show that the policy can achieve a higher resource utilization rate and lower rejection rate compared to the conventional reservation policy and backfilling technique. In addition, the policy shows better adaptation when the grid systems are in the presence of a high reservation rate.

关键词： grid computing advance reservation reservation violation computing economy

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Boron rings containing planar octa- and enneacoordinate cobalt, iron and nickel metal elements

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science china Chemistry 2008年第7期51卷 607-613页

作者： LUO Qiong school of Chemistry and Chemical engineering,{2., changsha 410083, china school of Chemistry and Chemical engineering Central South UniversityChangsha 410083China

For a series of boron rings with planar hyper-coordinate 8th group transition metal atoms, singlet 1FeB8-2. multiplet kFeB9n (n = -1, k = 1; n = 0, k = 2., singlet 1CoB8n(n = -1, +1, +3), multiplet kCoB9n (n = +1, k = 2. n = 0, k = 1) and singlet 1NiB9+, the geometry structures have been optimized to be local minima on corresponding potential hyper-surfaces. The electron structures are discussed by orbital analysis and the aromaticity is predicted by nucleus-independent chemical shifts calculation at both the B3LYP/6-311+G* and BP86/6-311+G* levels of theory, respectively. The results suggest that all these structures with high symmetry planar geometries are stable and have aromatic properties with six π valence electrons.

关键词： planar hyper-coordinate transition metal DFT

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Effect of aluminum-containing additives on the reactivity in air and CO_2.of carbon anode for aluminum electrolysis

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Rare Metals 2004年第2期23卷 109-114页

作者： LAI Yanqing LI Jie LI Qingyu DING Fengqi school of Metalling science and {2., central south university, changsha 410083, china school of Metallurgy science and {2. Central South University Changsha 410083 China

Airburn reaction and carboxy reaction result in the excess consumption ofcarbon anode in aluminum electrolysis. To reduce the excess carbon consumption, carbon anode wasdoped with aluminum-containing additives, such as Al, Al_4C_3, AlF_3 and Al_2._3. Their reactivityin air and CO_2.was determined with an isothermal-gravimetric method to study the effect ofaluminum-containing additives on the reactivity in air and CO_2.of carbon anode. Results shown thatthe airburn reactivity at 450℃ and carboxy reactivity at 970℃ of carbon anode both decreased withAl-containing additives adding, while shown a minimum with the amount of Al_4C_3, AlF_3 and Al_2._3increasing. However, all Al-containing additives increase the airburn reactivity at 550℃ of carbonanodes. Coke yield measurement and XRD examination with aluminum containing additives doped pitchcokes revealed that the effect of Al-containing additives on the airburn reactivity and carboxyreactivity of carbon anode would result from chemical factors and structural factors.

关键词： aluminum electrolysis aluminum-containing additives reactivity carbonanode

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Controllable synthesis of Ni-catalyzed tetragonal tungsten nanowires via chemical vapor deposition

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Progress in Natural science:materials International 2012年第5期22卷 514-519页

作者： Chao Wang a,Yuehui He a,Chaoqun Peng b,Shiliang Wang a,c,Xinli Liu a a State Key Laboratory of Powder Metallurgy,central south {2.,changsha 410083,china b school of material science and engineering,central south {2.,changsha 410083,china c school of Physics science and Technology,central south {2.,changsha 410083,china [a] State Key Laboratory of Powder Metallurgy Central South University Changsha 410083 China [b] school of material {2. and engineering Central South University Changsha 410083 China [c] school of Physics science and Technology Central South University Changsha 410083 China

Tetragonal single-crystal tungsten nanowires were successfully synthesized by chemical vapor deposition(CVD) catalyzed by Ni *** influences of the catalysts,temperature and growth time on the formation of the nanowires were *** was found that the tetragonal tungsten nanowires(WNWs) arrays were obtained by deterministic growth from the ordered Ni catalyst particles with one-to-one relation in size and position between the catalysts and *** large-scale tungsten nanowire arrays were synthesized at the low temperature of 950℃.Samples were characterized by X-ray diffraction(XRD),field-emission scanning electron microscopy(FE-SEM),transmission electron microscopy(TEM) and high-resolution transmission electron microscopy(HRTEM).Increasing growth time at 950℃,the tip of the WNWs changed from four(2.1) planes to four(110) *** controls of the orientation and structure of WNWs arrays were important for adjusting their properties to satisfy different requirements of potential nanodevices.

关键词： Tungsten nanowires Ni catalysts Chemical vapor deposition Nanostructures

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Characteristic atom arranging crystallogphy of alloy phases for Au-Cu system

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science china(Technological sciences) 2011年第6期54卷 1560-1567页

作者： XIE YouQing1,2.3,LIU XinBi1,2.3,PENG HongJian4,NIE YaoZhuang5,LI XiaoBo6 & LI YanFen1,2.3 1 school of materials {2. and engineering,central south university,changsha 410083,china 2.Powder Metallurgy Research Institute,central south university,changsha 410083 china 3 State Key Laboratory of Powder Metallurgy,central south university,changsha 410083,china 4 school of Chemistry and Chemical engineering,central south university,changsha 410083,china 5 school of Physical {2. and Technique,central south university,changsha,410083,china 6 College of Mechanical engineering,Xiangtan university,Xiangtan 411105,china 1. school of materials {2. and engineering Central South University Changsha 410083 China2. Powder Metallurgy Research Institute Central South University Changsha 410083 China3. State Key Laboratory of Powder Metallurgy Central South University Changsha 410083 China4. School of Chemistry and Chemical Engineering Central South University Changsha 410083 China5. School of Physical Science and Technique Central South University Changsha 410083 China6. College of Mechanical Engineering Xiangtan University Xiangtan 411105 China

In this paper,it is pointed out that the descriptions of alloy phase structures are dependent on structural unit *** the systematic science of alloys(SSA),the alloy phase structures are described by means of the symmetry element sequence combining with characteristic atom *** is named the characteristic atom arranging structure,which can display the characteristic atoms at the lattice sites and the micro-inhomogeneity,besides the *** characteristic atom has its own characters:neighboring configuration,potential energy,volume and electronic *** micro-inhomogeneity of alloy phases can be described by concentrations and short-range ordered parameters of characteristic *** differences between the electronic structures of alloy phases and electronic structures of characteristic atoms in the alloy phases are also discussed.

关键词： systematic science of alloys Au-Cu system alloy phase structure micro-inhomogeneity

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Mass Concentration of Particles (PM10) in Urban Environment of changsha,china

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湖南大学学报（自然科学版） 2009年第S1期36卷 5-9页

作者： TANG Meng,DENG Qi-hong,WANG Qi(school of Energy science & {2.,central south university,changsha,Hunan 410083,china) school of Energy science and {2. Central South University Changsha 410083 China

Continuous measurement of ambient PM10 was performed by TEOM at a university campus for about one year from 2. November 2.07 to 2. October 2.08 in changsha city of Hunan *** PM10 and PM2.5 concentration were measured by DustTrak simultaneously in order to describe the difference in concentration level and daily variations of particle mass concentration between different seasons,and to survey the influence of ambient particle on indoor air *** the survey period,the annual average PM10 concentration was found to be 117.63 μg/m3,with a mean value 12..88 μg/m3 in winter and 111.50 μg/m3 in *** temporal trend changed quickly from time to time,and the peak values were found in rush hours and in the *** PM10 showed a good correlation with indoor PM10 and outdoor PM2.5 but not with indoor *** results showed that PM10 was influenced by local source(such as traffic or fuel burning)and regional *** correlation analysis has shown that ambient PM10 contributes substantial fraction to indoor PM10 but not to indoor PM2.5,which indicates other source may exist in the indoor environment.

关键词： particle mass concentration human activity relationship

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Determination of phase equilibria in the Ni-Ta-Zr system at 12.3 K

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Rare Metals 2003年第3期22卷 160-163页

作者： PAN Ximiao and JIN ZhanpengPhase Diagram and materials Design Center, school of materials science and engineering, central south university, changsha 410083, china Phase Diagram and materials Design Center School of Materials Science and Engineering Central South University Changsha 410083

The phase equilibrium relations of the ternary Ni-Ta-Zr system at 12.3 K wereinvestigated by means of diffusion triple and electron probe microanalysis (EPMA) techniques. Twoternary compounds were found and a series of tie lines and tie triangles have been determined. Themaximum solubility of Ta in NiZr_2.is about 13.5% (atom fraction). The corresponding tentativeisothermal section at this temperature was constructed based on current experimental information.

关键词： phase diagram diffusion triple nickel EPMA Ni-Ta-Zr system

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Ti/Al_2._3 Functionally Gradient material Prepared by the Explosive Compaction/SHS Process

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Journal of materials science & Technology 1999年第3期15卷 271-275页

作者： Yimin LI(Powder Metallurgy Research Institute, central-south {2. of Technology, changsha 410083, china)Ziqiao ZHENG(Department of materials science and engineering, central-south {2. of Technology, changsha 410083, china) Cent S Univ Technol Powder Met Res Inst Changsha 410083 Peoples R China Cent S Univ Technol Dept Mat Sci & Engn Changsha 410083 Peoples R China

Ti1Al2.3 Functionally Gradient material (FGM) was prepared by an explosive compaction/SHS process. Ten sheets of the compounding powder were laminated and pressed to get a green body of FGM. It was then compacted explosively By burying the explosive compaction body into a stoichiometric Al/TiO2.mixture and igniting the combustion of the stoichiometric Al/TiO2.mixture, the SHS reaction of the explosive compaction body was initiated by the heat released from the combustion of the stoichiometric Al/TiO2.mixture. In this way, Ti/Al2.3 FGM was synthesized. The adiabatic temperatures of each gradient layer were calculated when the preheating temperatures were 2.8 K and 1173 K, respectively The microstructure, composition and properties of Ti/Al2.3 FGM and the reaction mechanism of each gradient layer were studied. It was found that Ti/Al2.3 FGM prepared by the explosive compaction/SHS process had a high density and a high microhardness. Its structure, composition and properties showed apparent gradient distribution. The structure of the standard stoichiometric ratio gradient layer of FGM was a network structure. Its reaction mode could be described as follows: Al powder melted first, then the molten Al penetrated into the TiO2.zone and reacted with TiO2. and big pores were left in the original positions of Al powder. The reaction of gradient layers with the addition of Al3O3 as diluents was similar to that of the standard stoichiometric ratio gradient layer, so were their structure and composition. However, the reaction of gradient layers with the addition of Ti as diluents was more complex and the composition deviated slightly from the designed one

关键词： Al SHS Ti/Al2.3 Functionally Gradient material Prepared by the Explosive Compaction/SHS Process

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On the design of compensator for quantization-caused input-output deviation

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science china(Information sciences) 2011年第4期54卷 824-835页

作者： GUO YuQian,GUI WeiHua & YANG ChunHua school of Information science and {2.,central south university,changsha 410083,china 1. school of Information science and {2. Central South University Changsha 410083 China

This paper considers the design of compensators for systems with quantized inputs in order to reduce the influence of *** systems with (vector) relative degrees,we propose a kind of compensators which can compensate for the accumulated output deviation completely caused by *** proposed compensators are capable of keeping the differences of the input-output responses between the systems with quantized inputs and the original systems without considering quantization within certain small *** show that the compensators in this paper are robust with respect to model uncertainties,disturbance and measurement noise and can significantly improve the input-output responses of systems with both input quantization and packet dropouts.

关键词： networked control systems quantization packet dropout I/O deviation compensation

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