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General expressions of peaked traveling wave solutions of CH-γ and CH equations

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science china Mathematics 2004年第6期47卷 862-873页

作者： ZHANG WenlingDepartment of Mathematics and Physics, national natural {2. foundation of {4., Beijing 100085, {4. 1. Department of Mathematics and Physics National Natural Science Foundation of China 100085 Beijing China

We use qualitative analysis and numerical simulation to study peaked traveling wave solutions of CH-γ and CH equations. General expressions of peakon and periodic cusp wave solutions are obtained. Some previous resul... 详细信息

关键词： peaked traveling waves general expressions numerical simulations

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. {4. Center of Safety science and Technology, State Administration of Work Safety, Beijing 10002., {2. 2. State Key Laboratory of Fire science, University of science and Technology of {2., Hefei 2.002., {2. 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 (GBZ2.2.02.. 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.

Materials and Sustainable Development

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Advances in Manufacturing 1998年第2期2卷 3-11页

作者： Shi Changxu (national natural {2. foundation of {4.)

Sustainable development refers to the establishment of resources saving industrial system and pursuing clean production; the promotion of efficiency of energy utilization and the development of new energy and renewable energy resources; the improvement of ecological environment and the continuous increase in agriculture and forest production; the reduction of environmental pollution and the decrease of the greenhouse effect, and the promotion of social sustainable development including birth control and improvement of the quality of population. They are all related to materials either directly or indirectly. In the present article, four topics are emphasized: 1. Effective utilization of natural resources and recycling of wastes should be emphasized. 2. Clean production of materials to minimize environmental pollution is urgent. 3. Development of materials systems based on elements which are abundant on the earth should be consi dered. 4. Development of advanced materials and novel process is a major way of saving resources and reducing environmental pollution.

关键词： materials sustainable development

Progress and review of the studies on the end-Triassic mass extinction event

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science china Earth sciences 2005年第12期48卷 2049-2060页

作者： DENG Shenghui1,2. LU Yuanzheng1,2.3 & XU Daoyi4.1. Research Institute of Petroleum Exploration and Development, Beijing 100083, china 2. Key Laboratory of Oil and Gas Reservoir of Petrochina, Beijing 100083, china 3. china University of Geosciences, Beijing 100083, china 4. Institute of Geology, china Earthquake Administration, Beijing 10002., china 1. Research Institute of Petroleum Exploration and Development 100083 Beijing China 2. Key Laboratory of Oil and Gas Reservoir of Petrochina 100083 Beijing China 3. china University of Geosciences 100083 Beijing China 4. Institute of Geology China Earthquake Administration 100029 Beijing China

The mass extinction at the end-Triassic is one of the five biggest in the Phanerozoic. However,it is the least well understood among these five events, and only till last decade it became a great academic interesting subject to geologists. The evidences for this event come obviously from bivalves, brachiopods, ammonites, corals, radiolaria, ostracods and foraminifera of marine habitats, and plants and tetrapods of terrestrial realm. By contrast, for some of other groups, such as marine gastropods and marine vertebrates, no mass extinction has been recog-nized yet. The extinction event is strongly marked at specific level but shown a complicated situa-tion at generic and family levels. Dramatic changing of the environment, such as the temperature raise due to the greenhouse effect, the marine anoxic habitats caused by a sudden transgression after the regression at the end of Triassic, has been claimed to be the main cause of the extinction. Many hypotheses have been suggested to demonstrate the mechanisms of the environment changing, among which two popular ones are the bolide impact and volcanic eruption. The Triassic-Jurassic (Tr-J) boundary mass extinction event is still poorly understood because no enough data have been obtained from the Tr-J boundary successional sections of both marine and terrestrial sediments, and most of these studies were regionally restricted. The basic aspects of the event and its associated environmental conditions remain poorly characterized and the causal mechanism or mechanisms are equivocal. Some authors even doubt its occurrence. china has many successionally developed terrestrial and marine Tr-J sections. Detailed studies of these sections may be important and significant for well understanding of the event.

关键词： progress, review, end-Triassic, mass extinction, mechanism, Tr-J boundary.

FUTURE OF HIGH TEMPERATURE MATERIALS FOR GAS TURBINE

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Acta Metallurgica Sinica(English Letters) 1996年第6期9卷 391-406页

作者： C.X. Shi(national natural {2. foundation of {4., Beijing 100083, {4. )

A comprehensive survey was made of various candidate high temperature materials for gas turbine use, and their relative merits and drawbacks were assessed. It is shown that superalloys, fine-tuned, will be persistent for the next few decades, to be followed up by high temperature intermetallics. For advanced ceramics, the problems of reliability and cost will have to be solved before they can be used in critical parts of *** are C/C composites with their oxidation problem. Surface modification and development of thermal barrier coatings can effectively overcome many problems of gas turbine materials and these technologies should be emphasized.

关键词： superalloy intermetallic compound ceramic C/C composite,surface modification

A survey on routing in wireless sensor networks

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Progress in natural science:Materials Inter{2. 2007年第3期17卷 261-269页

作者： XIAO Renyi and WU Guozheng (Department of Information sciences, national {2. science {4. of china, Beijing 100085, china) [a]Department of Information sciences National Natural Science Foundation of China Beijing China

One of the most important issues in wireless sensor networks is data delivery service between sensors and the data collection unit (called sink). Although sensor networks and mobile ad hoc networks are similar to some extent, they are radically distinct in many aspects. Sensor networks have many unique features, making them more challenging and need further research efforts. The existing routing protocols for sensor networks can be classified as indicator-based and indicator-free. In this survey, we make a comparative study of these protocols. Open issues and research directions are pointed out as guidelines for our future work.

关键词： sensor network distributed system routing ad-hoc network.

Transport network and flow mechanism of shallow ore-bearing magma in Tongling ore cluster area

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science china Earth sciences 2006年第4期49卷 397-407页

作者： DENG Jun1,2. WANG Qingfei1,2., HUANG Dinghua3 , WAN Li4. YANG Liqiang1,2.& GAO Bangfei1,2.1. State Key Laboratory of Geological Processes and Mineral Resources, {4. University of Geosciences, Beijing {2.3, {4. 2. Key Laboratory of Lithosphere Tectonics and Lithoprobing Technology of Ministry of Education, {4. University of Geo- sciences, Beijing {2.3, {4. 3. Faculty of Earth sciences, {4. University of Geosciences, Wuhan 4.0074. {4. 4. School of Mathematics and Information science, Guangzhou University, Guangzhou 5104.5, {4. 1. State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Beijing 100083 China 2. Key Laboratory of Lithosphere Tectonics and Lithoprobing Technology of Ministry of Education China University of Geosciences Beijing 100083 China 3. Faculty of Earth sciences China University of Geosciences Wuhan 430074 China 4. School of Mathematics and Information science Guangzhou University Guangzhou 510405 China

Abundant studies revealed that shallow intrusions of the Yanshanian epoch resulted in the mass mineralization of the Tongling region. Various evidences showed there existed a concealed magma chamber at ?10 km depth in the middle part of this region during Yanshanian epoch, from which the ore-forming magma was generated and then transported to the superficial layer. Yet the transport network and flow mechanism of the shallow ore-bearing magma, the key problem associ- ated with ore-forming process, was relatively little focused on. Integrate analysis of structural me- chanics, statistical fractal and geological facts suggested that NE trending high-angle fold-related thrust faults and the tessellated basement ones served as the main pathways for the shallow magma’s transporting, moreover, the saddle void spaces among adjacent strata in the folds upon this fault system provided the place for magma’s emplacement. So the folds in the upper part and faults in the lower part of the upper crust constituted the fluid’s transport and emplacement network. During the deformation of geologic body with multi-layer structure, the layers in the upper part tended to fold when received the jacking stress from the lower part, while the lower one inclined to fault undergoing loads of the upper part. And the producing probability of this structure assemblage was highly in- creased in the condition, such as in the Tongling area, that the mechanic rigidity of the lower layers was stronger than that of the upper ones. For the pre-existence of fluid-conducting network, the top magma with high volatile in the magma chamber transported rapidly to the superficial layer in dyking pattern, located in the void spaces of folds, filled and reconstructed them. The sudden drop of pres- sure caused the fluid unmixing from the magma and mass ore-forming elements concentration. Pulse activity of the dyking may be the principal reason why magmatic bodies in the Tongling area were spatially-temporally con

关键词： Tongling, structural network, magma intrusion, fractal, dyke.

WJG sets an example of internationalization for other Chinese academic journals

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World Journal of Gastroenterology 2010年第22期16卷 2707-2709页

作者： Guang-An Zu, Department of Publication, national natural {2. foundation of {4., Beijing 100085, {4. Department of Publication National Natural Science Foundation of China

Supported by the "Special Fund for Key Academic Journals" of the national natural {2. foundation of {4., World Journal of Gastroenterology (WJG ) has become a high-impact international clinical medical journal due to the great efforts of Professor LianSheng Ma, Editor-in-Chief, and his team over several years. Now, WJG has successfully achieved a high degree of internationalization and sets a good example for other Chinese academic journals.

关键词： china Academic journals Internationalization

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, {4. 2. Department of Mechanics & Engineering science, Peking University, Beijing 100871, {4. 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.