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Simulation of three-dimensional nonideal MHD flow at high magnetic Reynolds number

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中国科学：技术科学英文版 2010年第1期53卷 206-212页

作者： LU HaoYu1 & Lee ChunHian2 1 School of Astronautics,Beihang University,Beijing 100191,china 2 National laboratory for Computational Fluid Dynamics,Beihang University,Beijing 100191,china 1. School of Astronautics Beihang University Beijing 100191 China2. National Laboratory for Computational Fluid Dynamics Beihang University Beijing 100191 China

A conservative TVD scheme is adopted to solve the equations governing the three-dimensional flow of a nonideal compressible conducting fluid in a magnetic *** eight-wave equations for magnetohydrodynamics(MHD) are proved to be a non-strict hyperbolic system,therefore it is difficult to develop its *** developed a new set of equations which cannot be numerically simulated by conservative TVD scheme directly due to its non-conservative form.A conservative TVD scheme augmented with a new set of eigenvectors is proposed in the *** validate this scheme,1-D MHD shock tube,unsteady MHD Rayleigh problem and steady MHD Hartmann problem for different flow conditions are *** simulated results are in good agreement with the existing analytical *** this scheme can be used to effectively simulate high-conductivity fluids such as cosmic MHD problem and hypersonic MHD flow over a blunt body,etc.

关键词： magnetohydrodynamics(MHD) numerical simulation TVD MHD Rayleigh flow MHD Hartmann flow

Sharpness on the Lower Bound of the Lifespan of Solutions to Nonlinear Wave Equations

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Chinese Annals of Mathematics,Series B 2011年第4期32卷 521-526页

作者： Yi ZHOU 1 Wei HAN 2 1 Nonlinear Mathematical Modeling and Methods laboratory Shanghai Key laboratory for Contem- porary Applied Mathematics School of Mathematical Sciences, Fudan University, Shanghai 200433, china. 2 School of Mathematical Sciences, Fudan University, Shanghai 200433, china Department of Mathematics, North University of china, Taiyuan 030051, china. Nonlinear Mathematical Modeling and Methods laboratory Shanghai Key Laboratory for Contemporary Applied Mathematics School of Mathematical Sciences Fudan University Shanghai 200433 China

This paper is devoted to proving the sharpness on the lower bound of the lifespan of classical solutions to general nonlinear wave equations with small initial data in the case n = 2 and cubic nonlinearity （see the results of T. T. Li and Y. M. Chen in 1992）. For this purpose, the authors consider the following Cauchy problem： { where □=δt^2-∑i=1n δx^^2 is the wave operator, g（x）（≡/） 0 is a smooth non-negative function with compact support, and ε 〉 0 is a small parameter. It is shown that the solution blows up in a finite time, and the lifespan T（ε） of solutions has an upper bound T（ε） ≤ exp（Aε-2） with a positive constant A independent of ε, which belongs to the same kind of the lower bound of the lifespan.

关键词： Nonlinear wave equation Cauchy problem Lifespan

Preliminary study on the origin identification of natural gas by the parameters of light hydrocarbon

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Science china Earth Sciences 2008年第S1期51卷 131-139页

作者： HU GuoYi 1,2,3 ,LI Jian 1,2 ,LI Jin 1,2 ,LI ZhiSheng 1,2 ,LUO Xia 1,2 ,SUN QingWu 1,2 &MA ChengHua 1,2 1 Research Institute of Petroleum Exploration and Development(Langfang Branch),Petrochina,Langfang 065007,china 2 The Key laboratory of Gas Formation and Development,Petrochina,Langfang 065007,china 3 College of Geo-Resources and Information,china University of Petroleum,Beijing 102200,china Petrochina Res Inst Petr Explorat & Dev Langfang Branch Langfang 065007 Peoples R China Petrochina Key Lab Gas Format & Dev Langfang 065007 Peoples R China china Univ Petr Coll Georesources & Informat Beijing 102200 Peoples R China

The light hydrocarbon composition of 209 natural gas samples and individual light hydrocarbon carbon isotopes of 53 natural gas samples from typical humic-sourced gas and sapropelic-sourced gas in the four basins of china have been determined and *** identification parameters for humic-sourced gas and sapropelic-sourced gas are proposed or *** differences of compound-specificδ13C value of individual light hydrocarbon between humic-sourced gas and sapropelic-sourced gas have been *** humic-sourced gas has the distribution ofδ13C benzene > -24‰,δ13C toluene >-23‰,δ13C cyclohexane >-24‰andδ13C methyl cyclohexane >-24‰,while the sapropelicsourced gas has the distribution ofδ13C benzene 24‰,δ13C toluene 24‰,δ13C cyclohexane 24‰and δ13C methyl cyclohexane 24‰.Among the components of C7 light hydrocarbon compound,such as normal heptane(nC7),methyl cyclohexane(MCH)and dimethyl cyclopentane(ΣDMCP),etc,relative contents of nC7 and MCH are influenced mainly by the source organic matter type of natural ***,it is suggested that the gas with relative content of nC7 of more than 30%and relative content of MCH of less than 70%is sapropelic-sourced gas,while gas with relative content of nC7 of less than 35%and relative content of MCH of more than 50%is humic-sourced *** components of C5-7 aliphatics, the gas with relative content of C5-7 normal alkane of more than 30%is sapropelic-sourced gas,while the gas with relative content of C5-7 normal alkane of less than 30%is humic-sourced *** paremeters have been suggested to identify humic-sourced gas and sapropelic-sourced gas.

关键词： natural gas humic-sourced gas sapropelic-sourced gas carbon isotope light hydrocarbon parameters

Shell effect and capture cross sections in the synthesis of superheavy nuclei

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Science china(Physics,Mechanics & Astronomy) 2009年第10期52卷 1489-1493页

作者： DU SaiSai1,2,BIAN BaoAn1,2,3,LIU Min1,2,4,FENG ZhaoQing5,6 & ZHANG FengShou1,2,6 1 Key laboratory of Beam Technology and Material Modification of Ministry of Education,College of Nuclear Science and Technology,Beijing Normal University,Beijing 100875,china 2 Beijing Radiation Center,Beijing 100875,china 3 School of Science,Jiangnan University,Wuxi 214122,china 4 College of Physics and Technology,Guangxi Normal University,Guilin 541004,china 5 Institute of Modern Physics,Chinese Academy of Sciences,Lanzhou 730000,china 6 Center of Theoretical Nuclear Physics,National laboratory of Heavy Ion accelerator of Lanzhou,Lanzhou 730000,china Key laboratory of Beam Technology and Material Modification of Ministry of Education College of Nuclear Science and Technology Beijing Normal University Beijing 100875 China Beijing Radiation Center Beijing 100875 China School of Science Jiangnan University Wuxi 214122 China College of Physics and Technology Guangxi Normal University Guilin 541004 China Institute of Modern Physics Chinese Academy of Sciences Lanzhou 730000 China Center of Theoretical Nuclear Physics National Laboratory of Heavy Ion Accelerator of Lanzhou Lanzhou 730000 China

The shell effect is included in the improved isospin dependent quantum molecular dynamics model in which the shell correction energy of the system is calculated by using the deformed two-center shell model. A switch function is introduced to connect the shell correction energy of the projectile and the target with that of the compound nucleus during the dynamical fusion process. It is found that the calculated capture cross sections reproduce the experimental data quantitatively at the energy near the Coulomb barrier. The capture cross sections for reaction 35 80 Br + 82 208 Pb → 117 288 X are also calculated and discussed.

关键词： superheavy nuclei transport theory shell effect cross sections

Rhodium catalyzed asymmetric Pauson-Khand reaction using SDP ligands

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Science china Chemistry 2006年第1期49卷 81-87页

作者： FAN Baomin1, LI Shen2, XIE Jianhua2, WANG, Lixin2, TU Yongqiang1 & ZHOU Qilin2 1. State Key laboratory of Applied Organic Chemistry,Lanzhou University,Lanzhou 730000,china 2. State Key laboratory of Elemento-organic Chemistry,Nankai University,Tianjin 300071, china 1. State Key laboratory of Applied Organic Chemistry Lanzhou University Lanzhou 730000 China 2. State Key laboratory of Elemento-organic Chemistry Nankai University Tianjin 300071 China

The activity and enantiocontrol ability of the chiral catalysts prepared from spiro di-phosphine ligands, SDP, and rhodium precursor were investigated in the asymmetric catalytic Pau-son-Khand reaction. The results showed that SDP ligands were very effective in Rh-catalyzed Pau-son-Khand reaction, and their complexes with rhodium could convert a variety of 1,6-enyne compounds into bicyclopentone derivatives under CO atmosphere in high yields with good enantioselec-tivities. The SbF6- was found to be a suitable counter anion of the catalyst, and 1,2-dichloroethane was the best choice of the solvent for Pauson-Khand reaction.

关键词： Pauson-Khand reaction, asymmetric catalysis, diphosphine ligand, rhodium.

Homogenization-based multi-scale damage theory

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Science china(Physics,Mechanics & Astronomy) 2010年第4期53卷 690-698页

作者： LI Jie 1,2 & REN XiaoDan 1 1 School of Civil Engineering, Tongji University, Shanghai 200092, china 2 State Key laboratory of Disaster Reduction in Civil Engineering, Shanghai 200092, china 1. School of Civil Engineering Tongji University Shanghai 200092 China2. State Key Laboratory of Disaster Reduction in Civil Engineering Shanghai 200092 China

The research of modern mechanics reveals that the damage and failure of structures should be considered on different scales. The present paper is dedicated to establishing the multi-scale damage theory for the nonlinear structural analysis. Starting from the asymptotic expansion based homogenization theory, the multi-scale energy integration is proposed to bridge the gap between the micro and macro scales. By recalling the Helmholtz free energy based damage definition, the damage variable is represented by the multi-scale energy integration. Hence the damage evolution could be numerically simulated on the basis of the unit cell analysis rather than the experimental data identification. Finally the framework of the multi-scale damage theory is established by transforming the multi-scale damage evolution into the conventional continuum damage mechanics. The agree- ment between the simulated results and the benchmark results indicates the validity and effectiveness of the proposed theory.

关键词： Multi-scale damage representation asymptotic method constitutive model numerical simulation

Deformation in the Three Gorges Reservoir after the first impoundment determined by GPS measurements

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Progress in Natural Science:Materials International 2005年第6期15卷 515-522页

作者： DU Ruilin 1,2 , QIAO Xuejun 1,2 *, WANG Qi 1,2 , XING Canfei 1,2 and YOU Xinzhao 1,3 (1. Institute of Seismology, CEA, Wuhan 430071, china 2. laboratory of Crustal Movement and Earth Observation, Wuhan 430071, china 3. Center for Analysis and Prediction, CEA, Beijing 100036, china) Institute of Seismology CEA Wuhan 430071 China laboratory of Crustal Movement and Earth Observation Wuhan 430071 China Center for Analysis and Prediction CEA Beijing 100036 China

A 6-year long GPS observation (1998—2003) indicates that crustal deformation in the Three Gorges area is less active at a marginally measurable rate of 0—5 mm/a relative to stable South china block. However, the impounding water in June 2003 has induced transient displacement at the Three Gorges dam and the emerging reservoir. GPS measurements after the first stage of water filling of the reservoir demonstrate that vertical subsidence close by Yangtze River is about 10—40 mm, and the horizontal displacement is less than 5—10 mm. The maximum subsidence induced by the impoundment is located in the segment of the reservoir from Maoping to Xiangxi. The water loading-induced deformation diminishes rapidly with the distance from banks of the reservoir. The overall pattern of transient deformation is consistent with the simulation result of Farrell, and is attributed to the elastic response of upper lithosphere crust to overlying water reservoir.

关键词： Three Gorges GPS impoundment deformation.

Friction-reducing and antiwear behavior of metal halide-stabilized linear phosphazene derivatives as lubricants for a steel-on-steel contact

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Science china(Technological Sciences) 2005年第3期48卷 282-291页

作者： ZHU Jiamei 1,2 , LIU Weimin 2 & LIANG Yongmin 2 1. School of Chemical Engineering and Technology, china University of Mining and Technology, Xuzhou 221008, china 2. State Key laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, china 1. School of Chemical Engineering and Technology China University of Mining and Technology 221008 Xuzhou China 2. State Key laboratory of Solid Lubrication Lanzhou Institute of Chemical Physics Chinese Academy of Sciences 730000 Lanzhou China

A series of novel metal halide-stabilized linear phosphazene derivatives were synthesized. The friction-reducing and antiwear abilities of the resulting products as the lubricants for a steel-on-steel contact were comparatively investigated on an Optimol SRV oscillating friction and wear tester. The morphology of the worn steel surface was observed on a scanning electron microscope, while the chemical states of some typical elements on the worn steel surface were examined by means of X-ray photoelectron spectroscopy. It was found that both the side branch structures and central metals influenced the friction-reducing and antiwear behaviors of the synthetic derivatives as the lubricants, which was related to the different adsorption activities of the organic compounds composed of different organic ingredients and metallic ions on a nascent metal surface. All the synthetic lubricants except for the iron (III) derivative showed increased antiwear abilities with increasing metallic ionic radius. A protective layer originated from the tribochemical reaction together with the adsorbed boundary lubricating layer containing organic fluorine compounds, nitrogen oxide, and Fe 3 (PO 4 ) 2 plays an important role in improving the friction and wear behavior of the steel-on-steel system.

关键词： metal halide-stabilized linear phosphazene derivatives,lubricant,steel,tribological properties.

Experimental study on fire smoke movement in a multi-floor and multi-room building

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Science china(Technological Sciences) 2005年第3期48卷 292-304页

作者： ZHONG Maohua 1, 2 , LI Peide 2 , LIU Tiemin 1 , WEI Xing 1, 2 & LIAO Guangxuan 2 1. National Center of Safety Science and Technology, State Administration of Work Safety, Beijing 100029, china 2. State Key laboratory of Fire Science, University of Science and Technology of china, Hefei 230026, china 1. National Center of Safety Science and Technology State Administration of Work Safety 100029 Beijing China 2. State Key laboratory of Fire Science University of Science and Technology of China 230026 Hefei China

Fire smoke movement of multi-floor and multi-room (MFMR) fire was studied at the model test building in State Key laboratory of Fire Science (SKLFS). The ingredient, temperature, air pressure difference and air velocity of smoke were measured and analyzed. Meanwhile, the hazard of smoke ingredient to exposed occupants was analyzed based on the national standard, Occupational Exposure Limit for Hazardous Agents in the Workplace (GBZ2-2002). The experimental results showed that the maximum temperature difference in MFMR fire was located along the vertical height from the fire source. With the spreading and diffusion of smoke, the temperature of smoke layer would tend to be no difference. In the fire of woodpile and kerosene, the main smoke ingredients such as SO 2 , CO and CO 2 would first exceed human’s average physiological limit, while smoke ingredients such as NO and NO 2 would come behind. Because of the higher fluctuation range and frequency of air pressure difference of smoke in multi-layer building fire, the fire smoke would spread around everywhere of the passageway and made the human evacuation more difficult.

关键词： multi-floor and multi-room,fire experiment,smoke spread,smoke toxicity.