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The effects of shock wave and quasi-traveling wave in the mechanical impact test

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Science china(Technological Sciences) 2010年第9期53卷 2535-2541页

作者： WU Mei1,5,SUN ZhongFeng2,ZHANG LuMei3,CHEN Yong1 & JI LinHong4 1 Institute of High energy Physics,Chinese academy of Sciences,beijing 100049,china 2 School of Mathematical Sciences,Peking University,beijing 100871,china 3 High School of Central University for Nationalities,beijing 100081,china 4 Institute of Mechanical Design,Department of Precision Instruments and Mechanology,Tsinghua University,beijing 100084,china 5 academy of Opto-electronics,Chinese academy of Sciences,beijing 100190,china 1. Institute of High energy Physics Chinese Academy of Sciences Beijing 100049 China5. Academy of Opto-electronics Chinese Academy of Sciences Beijing 100190 China2. School of Mathematical Sciences Peking University Beijing 100871 China3. High School of Central University for Nationalities Beijing 100081 China4. Institute of Mechanical Design Department of Precision Instruments and Mechanology Tsinghua University Beijing 100084 China

It is well-known that the numerical value is always larger than the measured value,amounting to many times,if we calculate the stress of the specimen in the impulse test using the NASTRAN and ANSYS (N-A) *** believe that the impact induces shock wave or quasi-traveling wave in the specimen,which can qualitatively explain the discrepancy of the two *** order to verify it,the Lax-Friedrichs (L-F) scheme is taken to simulate the transmission of shock wave and quasi-traveling wave in *** results show that the action area of the stress wave is small and the action time is very short,so the resulting stress and actual work are not *** addition,the distribution of the impact values obtained by the numerical simulation is in accordance with the trend of the measured impact values.

关键词： aerospace environment test shock wave quasi-traveling wave

Theoretical study on homoleptic mononuclear and binuclear ruthenium carbonyls Ru(CO)_n(n=3―5) and Ru_2(CO)_n(n=8,9)

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Science china Chemistry 2009年第11期52卷 1938-1944页

作者： PENG Bin1,GU FengLong1,ZHANG XiuHui2,LUO Qiong2 & LI QianShu1,2 1 School of Chemistry and environment,South china Normal University,Guangzhou 510631,china 2 beijing Institute of Technology,beijing 100081,china 1. School of Chemistry and environment South China Normal University Guangzhou 510631 China 2. beijing Institute of Technology Beijing 100081 China

Homoleptic mononuclear and binuclear ruthenium carbonyls Ru(CO)n(n=3―5) and Ru2(CO)n(n=8,9) have been investigated using density functional *** isomers are *** Ru(CO)5,the lowest-energy structure is the singlet D3h trigonal *** to Os(CO)5,the distorted square pyramid isomer with C2v symmetry lies ～7 kJ·mol-1 higher in *** the unsaturated mononuclear ruthenium carbonyls Ru(CO)4 and Ru(CO)3,a singlet structure with C2v symmetry and a Cs bent Tshaped structure are the lowest-energy structures,*** global minimum for the Ru2(CO)9 is a singly bridged(CO)4Ru(μ-CO)Ru(CO)4 structure.A triply bridged Ru2(CO)6(μ-CO)3 structure analogous to the known Fe2(CO)9 structure is predicted to lie very close in energy to the global *** Ru2(CO)8,the doubly bridged C2 structure is predicted to be the global *** the lowest-energy structures of M2(CO)n(M=Fe,Ru,Os,n=9,8),it is found that both iron and ruthenium are favored to form structures containing more bridging carbonyl groups,while osmium prefers to have structures with less bridging carbonyl *** study of dissociation energy shows that the dissociation of Ru2(CO)9 into the mononuclear fragments Ru(CO)5+Ru(CO)4 is a less energetically demanding process than the dissociation of one carbonyl group from Ru2(CO)9 to give Ru2(CO)8.

关键词： dinuclear ruthenium carbonyls DFT theoretical study

Multi-scale sparse feature point correspondence by graph cuts

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Science china(Information Sciences) 2010年第6期53卷 1224-1232页

作者： ZHANG Hong 1 , MU Ying 1 , YOU YuHu 2 & LI JunWei 3 1 Image Processing Center, Beihang University, beijing 100191, china 2 beijing research Institute of Special Electromechanical Technology, beijing 100012, china 3 National Key Laboratory on Optical Features of environment and Target, beijing 100854, china 1. Image Processing Center Beihang University Beijing 100191 China2. Beijing Research Institute of Special Electromechanical Technology Beijing 100012 China3. National Key Laboratory on Optical Features of Environment and Target Beijing 100854 China

This paper presents a global stereo sparse matching technique based on graph cut theory to obtain accurate correspondence of stereo point pair in vision measurement ***, in order to obtain accurate location of feature points, a new multi-scale corner detection algorithm is proposed where wavelet coefficients are used to determine feature points by calculating an auto-correlation matrix.A sparse graph is constructed based on the feature points according to the graph cut ***, the feature point correspondence problem is transformed into a labeling problem in the sparse graph which can be solved by energy ***-scale analysis is utilized to improve the precision of matching *** was found that the use of sparse feature points in the construction of the graph can lead to both a simple graph structure and a reduced computational *** was also found that node labeling in the graph can be performed using fewer disparity values instead of all disparity *** experimental results show that the new global stereo sparse matching technique can obtain more accurate results than the existing techniques.

关键词： multi-scale feature point extraction graph cut theory stereo correspondence sparse point matching

Characteristics of energy dissipation in hyperconcentrated flows

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International Journal of Sediment research 2008年第4期23卷 387-397页

作者： An-ping SHU 1,Qing-quan LIU2,Yu-jun YI 3,and Zhi-dong ZHANG 41 Assoc.Prof.,School of environment,Key Laboratory of Water and Sediment Sciences of Ministry of Education,beijing Normal University,beijing 100875,china2 Prof.,Institute of Mechanics,Chinese academy of Sciences,beijing 100080,china3 Lecturer,Dr.,School of environment,beijing Normal University,beijing 100875,china4 Graduate student,School of environment,beijing Normal University,beijing 100875,china [a]Assoc. Prof. School of environment Key Laboratory of Water and Sediment Sciences of Ministry of Education beijing Normal University beijing 100875 china [b]Prof. Institute of Mechanics Chinese academy of Sciences beijing 100080 china [c]Lecturer Dr. School of environment beijing Normal University beijing 100875 china. The project is supported by the National Natural Science Foundation of china (Grant No. 10672024) [d]Graduate student School of environment beijing Normal University beijing 100875 china

An equilibrium equation for the turbulence energy in sediment-laden flows was derived on the basis of solid–liquid two-phase flow theory. The equation was simplified for two-dimensional, uniform, steady and fully developed turbulent hyperconcentrated flows. An energy efficiency coefficient of suspended-load motion was obtained from the turbulence energy equation, which is defined as the ratio of the sediment suspension energy to the turbulence energy of the sediment-laden flows. Laboratory experiments were conducted to investigate the characteristics of energy dissipation in hyperconcentrated flows. A total of 115 experimental runs were carried out, comprising 70 runs with natural sediments and 45 runs with cinder powder. Effects of sediment concentration on sediment suspension energy and flow resistance were analyzed and the relation between the energy efficiency coefficient of suspended-load motion and sediment concentration was established on the basis of experimental data. Furthermore, the characteristics of energy dissipation in hyperconcentrated flows were identified and described. It was found that the high sediment concentration does not increase the energy dissipation; on the contrary, it decreases flow resistance.

关键词： Hyperconcentrated flows Turbulence energy efficiency coefficient energy dissipation

Sediment transport capacity of hyperconcentrated flow

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Science china(Physics,Mechanics & Astronomy) 2008年第8期51卷 961-975页

作者： SHU AnPing1,2 & FEI XiangJun2 1 School of environment & Key Laboratory of Water and Sediment Sciences,Ministry of Education,beijing Normal University,beijing 100875,china 2 State Key Laboratory of Hydroscience and Engineering,Tsinghua University,beijing 100084,china School of environment & Key Laboratory of Water and Sediment Sciences Ministry of Education Beijing Normal University Beijing 100875 China State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China

As one of the most important components of river mechanics,sediment transport capacity of sediment-laden flows has attracted much attention from many researchers working on river mechanics and hydraulic engineering. Based on the time-averaged equation for a turbulent energy equilibrium in solid and liquid two-phase flow,an expression for the efficiency coefficient of suspended load movement was derived for the two-dimensional,steady,uniform,fully-developed turbulent flow. A new structural expression of sediment transport capacity was achieved. Using 115 runs of flume experimental data,which were obtained through two kinds of sediment transport experiments in the state of equilibrium,in combination with the basic rheological and sediment transporting characteristics of hyperconcentrated flow,the main parameters in the structural expression of sediment transport capacity were calibrated,and a new formula of sediment transport capacity for hyperconcentrated flow was developed. A large amount of field data from the Yellow River,Wuding River,and Yangtze River,etc. were adopted to verify the new formula and good agreement was obtained. These results above contribute to an improved theoretical system of river mechanics and a reliable tool for management of rivers carrying high concentration of sediments.

关键词： hyperconcentrated flow turbulent energy equilibrium efficiency coefficient sediment transport capacity

Characterization and Corrosion Resistance of Laser Clad-ding Al_2O_3-13%TiO_2 Coating on AZ91D Magnesium Alloy

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稀有金属材料与工程 2011年第S4期40卷 221-225页

作者： Qian Jiangang1,Zhang Jiaxiang1,2,Xu Min1,2,Li Shuqing2 1School of Chemistry and environment,beijing University of Aeronautics and Astronautics,beijing 100191,china2National Key Laboratory for High energy Density Beam Processing Technology,beijing 100024,china beijing Univ Aeronaut & Astronaut Sch Chem & Environm Beijing 100191 Peoples R China Natl Key Lab High energy Dens Beam Proc Technol Beijing 100024 Peoples R China

An Al2O3-13%TiO2 (AT-13) ceramic coating was prepared on an AZ91D Mg alloy substrate by the laser plasma hybrid spraying technique.X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to identify the phases and to study the morphology,*** adhesion strength and the metallographic structure of the coating were measured by using a tensile testing machine and an optical microscope (OM),*** microhardness was measured using a micro Vickers hardness *** results show that after laser remelting,metallurgic bonding occurred at the interface between the Al transition layer and the *** adhesion strength of the coating increased from 17.01 to 28.47 *** coating became *** metastable γ-Al2O3 phase in the coating without laser remelting transformed completely into the stable α-Al2O3 *** microhardness was improved from HV0.05210 to HV0.05425 and the time of salt spraying increased from 288 to 336h.

关键词： laser plasma hybrid spraying Mg alloy corrosion resistance

Potential land for plantation of Jatropha curcas as feedstocks for biodiesel in china

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Science china Earth Sciences 2010年第1期53卷 120-127页

作者： WU WeiGuang 1,2,3,HUANG JiKun 1,3 & DENG XiangZheng 1,3 1 Institute of Geographic Sciences and Natural Resources research,Chinese academy of Sciences,beijing 100101,china 2 Department of Economics and Management,Zhejiang Forestry University,Linan 311300,china 3 Center for Chinese Agricultural Policy,Chinese academy of Sciences,beijing 100101,china 1. Institute of Geographic Sciences and Natural Resources research Chinese Academy of Sciences Beijing 100101 China2. Department of Economics and Management Zhejiang Forestry University Linan 311300 China3. Center for Chinese Agricultural Policy Chinese Academy of Sciences Beijing 100101 China

As a renewable energy,biofuel has attracted great attention in china and the rest of *** with the national food security,china recently has shifted its biofuel development priority from grain-based to non-grain-based biofuels,including forest-based biodiesel,since *** curcas is one of major biodiesel ***,there is rising debate on availability of land for expanding Jatropha curcas *** overall goal of this paper is to evaluate potential land for Jatropha curcas used as feedstock for biodiesel in *** on remote sensing data on land use,data on meteorological,soil and land slope,and suitable environment for Jatropha curcas plantation,this study uses Agro Ecological Zone method and considers social-economic constraints to evaluate potential suitable land for Jatropha curcas plantation in china's major Jatropha curcas production region,Southwest *** results show that while there are some potential lands to expand Jatropha curcas areas,amount of these lands will hardly meet the government's target for Jatropha curcas-based biodiesels development in the *** may need to reconsider its long-term targets on the development of Jatropha curcas-based biodiesels.

关键词： biodiesel Jatropha curcas potential land suitability evaluation Southwest china

Fundamental study of CO_2 control technologies and policies in china

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Science china(Technological Sciences) 2008年第7期51卷 857-870页

作者： JIN HongGuang1, ZHANG XiLiang2, GAO Lin1, YUE Li2, HE JianKun2 & CAI RuiXian1 1 Institute of Engineering Thermophysics, Chinese academy of Sciences, beijing 100080, china 2 Institute of Nuclear and New energy Technology, Tsinghua University, beijing 100084, china 1. Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing 100080 China 2. Institute of Nuclear and New energy Technology Tsinghua University Beijing 100084 China

The technical roadmap and policies for CO2 mitigation suitable for china are a common center of attention in the fields of energy, environment, and management science in the country. Emphasizing interaction between technical research and policy research, this work discovers the potential breakthrough in the integrated field. The technical difficulties of recovering CO2 are pointed out, the mechanism of combining CO2 recovery with energy conversion is investigated, and the basic principle for integrating an environmental-friendly energy system is discussed. Moreover, the formulation of a new energy system that can recover CO2 with very low or even zero energy penalty is proposed, while the assessment methodology and model system for the technical roadmap of CO2 emission control are developed. Finally, a new technical roadmap constructing an energy network suitable for china is proposed, which may provide a new way for the development of sustainable energy and environment technologies.

关键词： CO2 capture and storage technical roadmap energy policy

Alkaline diagenesis and its genetic mechanism in the Triassic coal measure strata in the Western Sichuan Foreland Basin,china

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Petroleum Science 2009年第4期6卷 354-365页

作者： Jiang Zaixing Qiu Longwei Chen Guiju College of energy China University of GeosciencesBeijing 100083China College of Earth Resources and Information China University of PetroleumShandong 257062China Sinopec Exploration and Production research Institute Beijing 100083China

The reservoir of the upper Triassic Xujiahe Formation (T3x) in the Western Sichuan Foreland Basin is a set of terrigenous clastic rocks in an environment of coal measure sediments. Diagenesis greatly controls the physical properties of the reservoir through different responses of minerals to acidic and alkaline diagenetic environment. The dissolution of unstable components such as feldspar, rock fragments, carbonate cement, and clay minerals is the major source of secondary pores under acidic diagenesis, while the dissolution of quartz increases the reservoir space in the fault-fold zone of Longmen Mountain and Leikoupo paleo-hills. The dissolution of quartz is a result of cross-formation flow of fluid in the Himalaya epoch and the invasion of alkaline formation water from the Triassic Leikoupo and Jialingjiang formations through fault and fracture systems. In the vertical succession, acidic dissolution occurs at a shallow depth of less than 2,180 m, and alkaline dissolution occurs at a greater depth of more than 2,280 m. The reservoir space is formed by the influence of both acidic and alkaline dissolution in the depth interval of 2,180–2,280 m.

关键词： Sichuan Basin upper Triassic alkaline diagenesis porosity genetic mechanism