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Numerical and experimental investigation of the fracture behavior of shock loaded alumina

science china(Physics,Mechanics & Astronomy) 2010年第2期53卷 244-252页

作者： REN HuiLan1,SHU XueFeng2 & LI Ping3 1 state key laboratory of explosion science and technology,beijing institute of technology,beijing 100081,china 2 institute of Applied Mechanics and Biomedical Engineering,Taiyuan University of technology,Taiyuan 030024,china 3 Labroratory for Shock Wave and Detonation Physics Research,institute of Fluid Physics,CAEP,Mianyang 610059,china 1. state key laboratory of explosion science and technology Beijing Institute of Technology Beijing 100081 China2. Institute of Applied Mechanics and Biomedical Engineering Taiyuan University of Technology Taiyuan 030024 China3. Labroratory for Shock Wave and Detonation Physics Research Institute of Fluid Physics CAEP Mianyang 610059 China

Plate impact expeiments are conducted to investigate the dynamic behavior of alumina by using one stage light gas gun. A ve-locity interferometer system for reflectors (VISAR) is used to obtain Hugoniot elastic limit and the free surface velocity profile,which consists of an elastic wave followed immediately by a dispersive inelastic wave. The stress histories under different impact velocities are measured by in-material manganin gauges. Based on the experimental data a Hugoniot curve is fitted,which shows the compressive characteristics that alumina changes typically from elastic to "plastic" ,and under higher pressure it will be transferred to similar-fluid state. The turning point of the Hugoniot curve from a high pressure region to a low pressure region is about 11.4 GPa. The fracture process of alumina is simulated by way of finite element code. After the analysis of the fracture mechanism,the numerical results show an important role played by the nucleation and the growth of the cracks in the macro-scopic fracture of the alumina target. The numerical predictions of stress histories are compared with the experimental results,which indicates consistency between them.

关键词： plate impact experiment hugoniot curve fracture characteristics numerical simulation

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Synthesis,Crystal Structure, Thermal Decomposition and Sensitivity Properties of (AIM)(HTNR) and (AIM)(PA)

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Chemical Research in Chinese Universities 2012年第1期28卷 4-8页

作者： TANG Zhan, YANG Li, QIAO Xiao-jing, WU Bi-dong, ZHANG Tong-lai, ZHOU Zun-ning and YU Kai-bei state key laboratory of explosion science and technology, beijing institute of technology, beijing 100081, P. R. china beijing Inst Technol State Key Lab Explos Sci & Technol Beijing 100081 Peoples R China

Two new energetic compounds （AIM）（HTNR） and （AIM）（PA）（AIM=2-azidoimidazole, TNR=2,4,6-trini troresorcinol, PA=picric acid） have been prepared by AIM（2-azidoimidazolium） and TNR（2,4,6-trinitroresorcinol） or PA（picric acid） and characterized by elemental analysis and FTIR spectrum. Their crystal structures were determined by X-ray single-crystal diffraction analysis. The obtained results show that （AIM）（HTNR） crystal belongs to monoc linic, P21/c space group, a=1.1306（2） nm, b=0.70305（14） nm, c=1.7398（4） nm, β=106.91°, V=1.3231（5） nm3, Dc=1.778 g/cm3, Z=4, R1=0.0524, wR2[I 〉2σ（I）]=0.1067 and S=1.092 and （AIM）（PA） crystal belongs to monoclinic P21/c space group, a=0.80303（16） nm, b=0.81395（16） nm, c=2.0471（4） nm, β=93.93（3）°, V=1.3349（5） nm3, Dc=1.683 g/cm3, Z=4, R1=0.0784, wR2[I〉2σ（I）]=0.1814 and S=1.098. Both the compounds have electrostatic attraction and hy drogen bonds, which contribute to making the constructions more stable. The decomposition of the two compounds was studied via differential scanning calorimetry（DSC） and thermogravimetry-derivative thermogravimetry（TG-DTG） techniques at a heating rate of 10 oC/min, and the results show that both the compounds underwent one intensive exothermic decomposition stage. Sensitivity tests reveal that the title compounds were insensitive to friction and im pact and sensitive to flame and could be applied in potential pyrotechnics.

关键词： 2-Azidoimidazolium 2,4,6-Trinitroresorcinol Picric acid Crystal structure Thermal decomposition

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Multiparty simultaneous quantum identity authentication with secret sharing

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science china(Physics,Mechanics & Astronomy) 2008年第3期51卷 321-327页

作者： YANG YuGuang1,2,WEN QiaoYan3 & ZHANG Xing4,5 1 College of Computer science and technology,beijing University of technology,beijing 100022,china 2 state key laboratory of Information Security (Graduate University of the Chinese Academy of sciences),beijing 100049,china 3 School of science,beijing University of Posts and Telecommunications,beijing 100876,china 4 institute of Electronic technology,Information Engineering University,Zhengzhou 450004,china 5 Trusted Computing laboratory,beijing University of technology,beijing 100022,china College of Computer science technology Beijing University of Technology Beijing 100022 China state key laboratory of Information Security [Graduate University of the Chinese Academy of sciences] Beijing 100049 China School of science Beijing University of Posts Telecommunications Beijing 100876 China institute of Electronic technology Information Engineering University Zhengzhou 450004 China Trusted Computing laboratory Beijing University of Technology Beijing 100022 China

Two multiparty simultaneous quantum identity authentication (MSQIA) protocols based on secret sharing are presented. All the users can be authenticated by a trusted third party (TTP) simultaneously. In the first protocol,the TTP shares a random key K with all the users using quantum secret sharing. The ith share acts as the authentication key of the ith user. When it is necessary to perform MSQIA,the TTP generates a random number R secretly and sends a sequence of single photons encoded with K and R to all the users. According to his share,each user performs the corresponding unitary operations on the single photon sequence sequentially. At last,the TTP can judge whether the impersonator exists. The sec-ond protocol is a modified version with a circular structure. The two protocols can be efficiently used for MSQIA in a network. They are feasible with current technol-ogy.

关键词： quantum identity authentication secret sharing quantum cryptography

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Surface interrogation mode of scanning electrochemical microscopy for oxidation study of adsorbed CO generated from serine on platinum

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Chinese Chemical Letters 2011年第12期22卷 1481-1484页

作者： Chun Cui Huang,Qian Wang,De Bo Xiang,Hui Bo Shao~* key laboratory of Cluster science,Ministry of Education of china,School of Chemistry, beijing institute of technology,beijing 100081,china key laboratory of Cluster science Ministry of Education of China School of Chemistry Beijing Institute of Technology Beijing 100081 China

We report a new method for detection and oxidation of adsorbed carbon monoxide(CO;) generated from serine on a polycrystalline platinum ultramicroelectrode（UME） by bromine（Br;） using in situ surface interrogation（SI） mode of scanning electrochemical microscopy（SECM）.In the SI mode,tip and substrate are both Pt UMEs,and CO;on Pt substrate,generated from serine,can be oxidized by the tip-generated Br;giving a positive *** CO;from serine instead of purging CO gas expands the newly introduced reaction of Br;with CO;and further enhances the hope to get rid of CO;on Pt for fuel cells.

关键词： SECM Surface interrogation mode Adsorbed carbon monoxide Serine Pt ultramicroelectrode

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Fracture characteristics of concrete subjected to impact loading

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science china(Physics,Mechanics & Astronomy) 2010年第9期53卷 253-261页

作者： LIU HaiFeng1,2,LIU HaiYan3 & SONG WeiDong1 1 state key laboratory of explosion science and technology,beijing institute of technology,beijing 100081,china 2 School of Civil and Hydraulic Engineering,Ningxia University,Yinchuan 750021,china 3 School of science,beijing institute of technology,beijing 100081,china 1. state key laboratory of explosion science and technology Beijing Institute of Technology Beijing 100081 China2. School of Civil and Hydraulic Engineering Ningxia University Yinchuan 750021 China3. School of Science Beijing Institute of Technology Beijing 100081 China

This paper takes concrete as a four-phase composite made of the intact matrix and three mutually perpendicular groups of penny-shaped micro-cracks. The intact matrix is assumed to be elastic,homogeneous and isotropic,and the micro-cracks are penny-shaped. Combined with the failure mechanism of concrete subjected to impact loading,a dynamic constitutive model for concrete is developed based on Mori-Tanaka's average stress concept and Eshelby's equivalent inclusion theory. Experimental results show that concrete is rate-dependent. The model predictions are in good agreement with the experimental results. The model may be used to simulate the mechanical behavior of concrete under impact loadings.

关键词： concrete micromechanics impact loading constitutive model

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On the placement of actuators and sensors for flexible structures with closely spaced modes

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science china(Technological sciences) 2010年第7期53卷 1973-1982页

作者： LIU XiaoXiang1,2 & HU Jun1,2 1 beijing institute of Control Engineering, beijing 100190, china 2 state key laboratory of science and technology on Space Intelligent Control, beijing 100190, china 1. beijing institute of Control Engineering Beijing 100190 China2. State Key Laboratory of Science and Technology on Space Intelligent Control Beijing 100190 China

This paper analyzed the fundamental limitations of previous work and developed a new method to optimally locate actuators and sensors for structures with close modes. Optimization criteria were defined based on the distinguishing modal controllability and observability measures of close modes. An appropriate genetic algorism was adopted as the optimization algorism. Solving the high order Lyapunov functions was avoided by means of the closed-form expressions for controllability and observability Grammians. Since structure with widely separated natural frequencies is approximately balanced, computational efficiency was improved by grouping close modes together and dealing with the resulting subsystems independently. Finally, the effectiveness and optimality of the novel placement scheme were verified on a model structure with close modes.

关键词： close modes controllability/observability sensor/actuator optimization criterion optimization algorithm

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Influence of Ru addition on microstructure and stress-rupture property of Ni-based single crystal superalloys

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Progress in Natural science:Materials International 2010年第1期20卷 61-69页

作者： Jing-yang CHEN~1,Qiang FENG~(1,2),La-mei CAO~3,Zu-qing SUN~1 1.state key laboratory for Advanced Metals and Materials,University of science and technology beijing, beijing 100083,china 2.National Center for Materials Service Safety,University of science and technology beijing,beijing 100083,china 3.National key laboratory of science and technology on Advanced High Temperature Structural Materials, beijing institute of Aeronautical Materials,beijing 100095,china Univ Sci & Technol beijing State Key Lab Adv Met & Mat Beijing 100083 Peoples R China Univ Sci & Technol beijing Natl Ctr Mat Serv Safety Beijing 100083 Peoples R China beijing Inst Aeronaut Mat Natl Key Lab Sci & Technol Adv High Temp Struct M Beijing 100095 Peoples R China

The effects of Ru on the microstructure and stress-rupture property were investigated in two experimental Ni-based single crystal superalloys with and without Ru addition(5.1%,mass fraction).The results indicate that the morphology ofγ' precipitates in the dendrite core and interdendritic region are intermediate and nearly spherical,respectively,in the Ru-free alloy after being aged at 1100℃for 8 *** Re partitioning ratio increases due to Ru addition and Ru partitioned preferentially to theγphase in both dendrite core and interdendritic region of the Ru-containing alloy,which results in more negative lattice misfit and more cuboidalγ' ***,theγ' volume fraction increases while the precipitate size and y channel width decreases due to Ru addition in both dendrite core and interdendritic *** addition improves the stress-rupture life at 1100℃/140 MPa significantly due to higherγ' volume fraction,more negative lattice misfit and a well rafting structure as well as lessγchannel width.

关键词： Ni-based superalloys ruthenium elemental partitioning ratio lattice misfit γ’ morphology stress-rupture property

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Isomerization of B_6,B_6^- and B_6^+ clusters

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science china Chemistry 2010年第1期53卷 202-209页

作者： WEI GongMin1,PU ZhiFeng2,ZOU Rong3,LI GuoLiang2,3 & LUO Qiong2,3 1Department of Physics,Capital Normal University,beijing 100048,china 2state key laboratory of explosion science and technology beijing institute of technology,beijing 100081,china 3Center for Computational Quantum Chemistry,South china Normal University,Guangzhou 510631,china 1. Department of Physics Capital Normal University Beijing 100048 China2. State Key Laboratory of Explosion Science and Technology Beijing Institute of Technology Beijing 100081 China3. Center for Computational Quantum Chemistry South China Normal University Guangzhou 510631 China

The interconversions between isomers with the same spin multiplicity of neutral B6 and charged B6-and B6+ clusters have been investigated at the B3LYP/6-311+G level of theory,including determination of the minimum energy pathways with transition states connecting the corresponding reactants and *** dynamic calculations,26 isomers were optimized,including 11 novel *** order to further refine the energies,single-point B3LYP/6-311+G(3df) calculations were carried out on the corresponding B3LYP/6-311+G geometries of all isomers of B6,B6-and B6+ and the corresponding isomerization transition *** stability of each isomer of B6(singlet and triplet states),B6-(doublet state) and B6+(doublet state) was analyzed from both thermodynamic and dynamic viewpoints.

关键词： B6 transition state intrinsic reaction coordinate barrier height

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Analysis of forest backscattering characteristics based on polarization coherence tomography

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science china(Technological sciences) 2010年第S1期53卷 166-175页

作者： LUO HuanMin 1,LI XiaoWen 1,2,CHEN ErXue 3,CHENG Jian 4 & CAO ChunXiang 21 institute of Geo-Spatial Information science and technology,University of Electronic science and technology of china,Chengdu 610054,china 2 state key laboratory of Remote Sensing science,Jointly Sponsored by the institute of Remote Sensing Applications of Chinese Academy of sciences and beijing Normal University,beijing 100101,china 3institute of Forest Resources Information Technique of Chinese Academy of Forestry,beijing 100091,china 4 School of Electronic Engineering,University of Electronic science and technology of china,Chengdu 610054,china state key Lab Remote Sensing Sci Beijing 100101 Peoples R China beijing Normal Univ Beijing 100101 Peoples R China Univ Elect Sci & Technol china Inst Geospatial Informat Sci & Technol Chengdu 610054 Peoples R China Chinese Acad Forestry Inst Forest Resources Informat Tech Beijing 100091 Peoples R China Univ Elect Sci & Technol china Sch Elect Engn Chengdu 610054 Peoples R China

It is difficult to make an inventory of vertical profiles of forest structure parameters in field ***,analysis and understanding of forest backscattering characteristics contribute to estimation and detection of forest vertical structure because of the close relationships between backscattering characteristics and structure *** vertical structure function in the complex interferometric coherence definition,which represents the vertical variation of microwave scattering with the penetration depth at a point in the 2-D radar image and can be used to analyze the forest backscattering characteristics,can be reconstructed from polarization coherence tomography(PCT).Based on PCT,the paper analyzes the forest backscattering characteristics and explores the inherent relationship between the result of PCT and the forest structure parameters from numerical simulation of Random Volume over Ground model(RVoG),Polarimetric SAR interferometry(PolInSAR)simulation of forest scene and PolInSAR data at L-band of the test site ***,the effects of the extinction coefficient and surface-to-volume scattering ratio in RVoG model on vertical backscattering characteristics are analyzed by means of numerical ***,by applying PCT to L-band POLInSAR simulations of forest scene,different variations of vertical backscattering due to different extinction coefficients and the ratios of surface-to-volume scattering resulting from different polarizations,forest types and densities are displayed and *** a concept of relative average backscattering intensity is presented,and the factors which affect its vertical distribution are also *** results show that there is high sensitivity of the vertical distribution of forest relative average backscattering intensity to the polarization,forest type and ***,based on repeat pass DLR E-SAR L-band airborne POLInSAR data,the capability of PCT technology for detection

关键词： backscattering characteristic POLInSAR PCT vertical structure function

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Manufacture of the Ultrafine Grain WC/Co Cemented Carbides by Combined Sintering Processing

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International Journal of Minerals,Metallurgy and Materials 1999年第3期13卷 208-213页

作者： Binghai Liu Yue Zhang Shixi Ouyang Qikai Li(institute of Technical Physics and Chemistry, East china University of science and technology , Shanghai 200237, china)(Material science and Engineering School. University of science and technology beijing, beijing 100083, china)(state key laboratory for Synthesis and Processing of Advanced Materials. Wuhan University of science and technology, Wuhan 430070, china,) E china Univ Sci & Technol Inst Tech Phys & Chem Shanghai 200237 Peoples R China Univ Sci & Technol beijing Sch Mat Sci & Engn Beijing 100083 Peoples R China Wuhan Univ Sci & Technol State Key Lab Synth & Proc Adv Mat Wuhan 430070 Peoples R China

A new kind of sintering process, combined sintering process. i.e. vacuum sintering plus hot isolate pressure sintering (HIP), was introduced for producing ultrafine WC-10% Co (mass fraction. so as the follows) cemented carbides. The effects of some processing parameters on the microstructure and mechanical properties of the obtained cemented carbides were studied. The results show that the rapid shrinkage and the pronounced densification of tile cemented carbides took place during the vacuum sintering stage, which is intinaately correlated with the local liquid sintering occurred during this earl} sintering stage for the high surface activity of ultrafine WC-Co powder. The way of high pressure imposing. isothermal treatment cycle during *** sintering and HIP sintering stage directly influence the densitication of compacts and the mechanical properties of the produced WC-10%Co cemented carbides.

关键词： ultrafine WC-Co cemented carbides vacuum sintering HIP sintering

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