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Communications in Nonlinear science and Numerical Simulation 1996年第4期1卷 42-51页

作者： Chunguang XU (College of Mathematical science ,peking university, beijing 100871) College of Mathematical science peking university beijing 100871 USA

Ａｂｓｔｒａｃｔ：ＴｈｅｉｎｖｅｓｔｉｇａｔｉｏｎｏｆＭａｃｈｒｅｆｌｅｃｔｉｏｎｆｏｒｍｅｄａｆｔｅｒｔｈｅｉｍｐｉｎｇｅｍｅｎｔｏｆａｗｅａｋｐｌａｎｅｓｈｏｃｋｗａｖｅｏｎａｗｅｄｇｅ，ｗｉｔｈｓｈｏｃｋＭａｃ... 详细信息

Ａｂｓｔｒａｃｔ：ＴｈｅｉｎｖｅｓｔｉｇａｔｉｏｎｏｆＭａｃｈｒｅｆｌｅｃｔｉｏｎｆｏｒｍｅｄａｆｔｅｒｔｈｅｉｍｐｉｎｇｅｍｅｎｔｏｆａｗｅａｋｐｌａｎｅｓｈｏｃｋｗａｖｅｏｎａｗｅｄｇｅ，ｗｉｔｈｓｈｏｃｋＭａｃｈｎｕｍｂｅｒＭｓｎｅａｒ１，ｉｓｓｔｉｌａｎｏｐｅｎｐｒｏｂｌｅｍ［１２］．Ｉｔ＇ｓｄｉｆｉｃｕｌｔｆｏｒｓｈｏｃｋｔｕｂｅｅｘｐｅｒｉｍｅｎｔｓｗｉｔｈｉｎｔｅｒｆｅｒｏｍｅｔｅｒｔｏｄｅｔｅｃｔｃｏｎｔａｃｔｄｉｓｃｏｎ－ｔｉｎｕｉｔｉｅｓ，ｉｆｉｔｉｓｔｏｏｗｅａｋ；ａｌｓｏｄｉｆｉｃｕｌｔｔｏｃａｔｃｈｗｉｔｈｄｕｅａｃｃｕｒａｃｙｔｈｅｔｒａｎｓｉｔｉｏｎｃｏｎｄｉｔｉｏｎｂｅｔｗｅｅｎＭａｃｈｒｅｆｌｅｃｔｉｏｎａｎｄｒｅｇｕｌａｒｒｅｆｌｅｃｔｉｏｎ．Ｔｈｅｉｎｔｅｒｅｓｔｔｏｔｈｉｓｐｈｅｎｏｍｅｎｏｎｉｓｃｏｎｔｉｎ－ｕｉｎｇ，ｅｓｐｅｃｉａｌｙｆｏｒｗｅａｋｓｈｏｃｋｓ，ｂｅｃａｕｓｅｔｈｅｒｅｗａｓｓｙｓｔｅｍａｔｉｃｄｉｓｃｒｅｐａｎｃｙｂｅｔｗｅｅｎｓｉｍ－ｐｌｉｆｉｅｄｔｈｒｅｅｓｈｏｃｋｔｈｅｏｒｙｏｆｖｏｎＮｅｕｍａｎｎ［８］ａｎｄｓｈｏｃｋｔｕｂｅｒｅｓｕｌｔ

关键词： weak reflection Mach reflection anti-diffusion

Hybrid microsystem with functionalized silicon substrate and PDMS sample operating microchannel: A reconfigurable microfluidics scheme

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science china(Technological sciences) 2010年第8期53卷 2272-2277页

作者： LEI YinHua 1 ,XIE Fei 1 ,WANG Wei 1,2 ,WANG HaiBin 3 &LI ZhiHong 1,2 1 institute of Microelectronics,peking university,beijing 100871,china 2National Key Laboratory of science and Technology on Micro/Nano Fabrication,beijing 100871,china 3 No.302 Hospital,beijing 100039,china 1. institute of Microelectronics Peking University Beijing 100871 China2. National Key Laboratory of Science and Technology on Micro/Nano Fabrication Beijing 100871 China3. No. 302 Hospital Beijing 100039 China

A hybrid microsystem with separately functioned temperature controlling substrate and sample operating fluidic microchannel was developed to demonstrate a reconfigurable microfluidics *** temperature controlling substrate integrated a micro heater and a temperature sensor by using traditional silicon-based micromechanical system(MEMS)technique,which guaranteed high performance and robust reliability for repeatable *** sample operating fluidic microchannel was prepared by poly-(dimethylsiloxane) (PDMS)based soft lithography technique,which made it cheap enough for disposable *** PDMS microchannel chip was attached to the temperature controlling substrate for reconfigurable thermal applications.A thin PDMS film was used to seal the microchannel and bridge the functionalized substrate and the sample inside the channel,which facilitated heat transferring and prevented sample contaminating the temperature controlling *** by a one dimensional thermal resistance model,the thin PDMS film was important for the present reconfiguration *** performance of this hybrid microsystem was examined,and the experimental results demonstrated that the chip system could work stably over hours with temperature variation less than *** PDMS microchannel chips were tested on one heating substrate sequentially with a maximum intra-chip temperature difference of *** extracted from serum of a chronic hepatitis B virus(HBV)patient was amplified by this hybrid microsystem and the gel electrophoresis result indicated that the present reconfigurable microfluidic scheme worked successfully.

关键词： reconfigurable microfluidics hybrid microdevice thin PDMS film

Effects of the CNTF-collagen gel-controlled delivery system on rat neural stem/progenitor cells behavior

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science china(Life sciences) 2010年第4期53卷 504-510页

作者： YANG ZhaoYang1, QIAO Hui2 & LI XiaoGuang1,3 1School of Biological science and Medical Engineering, Beihang university, beijing 100191, china 2Public Heath School, Ningxia Medical university, Yinchuan 750004, china 3beijing institute for Neuroscience, Capital Medical university, beijing 100069, china 1. School of Biological science and Medical Engineering Beihang University Beijing 100191 China2. Public Heath School Ningxia Medical University Yinchuan 750004 China3. Beijing Institute for Neuroscience Capital Medical University Beijing 100069 China

The injury of central nervous system (CNS) usually causes the cavity formation. Although transplantation of neural stem/precursor cells (NSPCs) into the lesioned area of CNS has been shown to be implicated in the functional restoration, the therapeutic result is limited by the poor survival of NSPCs as well as their insufficient proliferation and differentiation abilities. Type-1 collagen is considered as a candidate scaffold or drug delivery system to overcome the aforementioned obstacle. This study observed the effects of the CNTF (ciliary neurotrophic factor)-collagen gel-controlled delivery system and daily addition of soluble-form CNTF on the NSPC survival, migration, proliferation and differentiation. The results showed that, within 12 h of the initial co-culture, CNTF was released in a burst pattern, then the CNTF-collagen gel-controlled delivery system stably released CNTF for up to 12 d. The cell viability test, together with immunohistochemistry, RT-PCR and Western blotting, showed that the CNTF-collagen gel-controlled delivery system supported the NSPCs seeded on the surface of collagen gel survival and facilitated their migration and proliferation. The daily addition of soluble-form CNTF to the medium had similar effects to the CNTF-collagen gel-controlled delivery system, but large quantities of soluble-form CNTF were consumed during the entire process. Taken together, the CNTF-collagen gel-controlled delivery system not only provides a physical scaffold for the transplanted NSPCs to adhere and migrate, but also facilitates the NSPC survival, growth and proliferation, simultaneously reducing the consumption of the expensive growth factors. This system may be used to enhance the microenvironment in the lesioned area of CNS.

关键词： spinal cord neural stem/progenitor cells control release type-1 collagen CNTF

The precipitation and effect of nano nitrides in HSLC steel

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science china(Technological sciences) 2008年第7期51卷 989-998页

作者： FU Jie1, LIU YangChun1,2 & WU HuaJie1,3 1 School of Metallurgical and Ecological Engineering, university of science and Technology beijing, beijing 100083, china 2 Shougang Technology Research institute, Shougang (Group) Corporation, beijing 100041, china 3 Metallurgical Engineering Research institute, university of science and Technology beijing, beijing 100083, china 1. School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China 2. Shougang Technology Research institute Shougang (Group) Corporation Beijing 100041 China 3. Metallurgical Engineering Research institute University of Science and Technology Beijing Beijing 100083 China

The existing forms of N and Al in HSLC (high strength low carbon) steel produced by TSCR (thin slab casting and rolling process), the precipitation thermodynamics and kinetics of AlN, and its effects on structure and mechanical property are studied. The experimental results show that only a small quantity of nitrogen is com- bined into AlN in HSLC steel produced by TSCR and most of the nitrogen in steel is still free nitrogen. Aluminum-nitride is mainly precipitated during the period of slow air cooling after coiling, but not during rolling and water cooling. The acid-soluble aluminum has no obvious effect on the grain size and mechanical property of HSLC steel produced by TSCR whose acid-soluble aluminum content is 0.005%―0.043%. The precipitation of AlN is not the main cause of grain refinement of HSLC steel produced by TSCR, nor is AlN the dominating precipitate that has precipitation strengthening effect. The nano nitrides are not pure AlN, but have complex compositions.

关键词： thin slab casting and rolling high strength low carbon steel AlN nano nitride precipitation strengthening

THE APPLICATION OF DISCRETE ELEMENT METHOD IN SOLVING THREE-DIMENTIONAL IMPACT DYNAMICS PROBLEMS

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Acta Mechanica Solida Sinica 2003年第3期16卷 256-261页

作者： Liu Kaixin Gao Lingtian (Department of Mechanics and Engineering science,peking university,beijing 100871,china) Department of Mechanics and Engineering science Peking University Beijing 100871 China

A three-dimensional discrete element model of the connective type is presented. Moreover,a three-dimensional numerical analysis code,which can carry out the transitional pro- cess from connective model(for continuum)to contact model(for non-continuum),is developed for simulating the mechanical process from continuum to *** wave propagation process in a concrete block(as continuum)made of cement grout under impact loading is numer- ically simulated with this *** comparing its numerical results with those by LS-DYNA,the calculation accuracy of the model and algorithm is ***,the failure process of the concrete block under quasi-static loading is demonstrated,showing the basic dynamic tran- sitional process from continuum to *** results of calculation can be displayed by *** damage modes are similar to the experimental *** two numerical examples above prove that our model and its code are powerful and efficient in simulating the dynamic failure problems accompanying the transition from continuum to *** also shows that the discrete element method(DEM)will have broad prospects for development and application.

关键词： discrete element method three-dimensional model impact stress wave dynamic failure

Numerical Modeling of NO Formation during Packed-bed Combustion of Coke Granules

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International Journal of Minerals,Metallurgy and Materials 2000年第4期14卷 261-268页

作者： Chunbao Xu, Shengli Wu, Daqiang Cang (Metallurgy School, university of science and Technology beijing, beijing 100083, china institute for Chemical Reaction science, Tohoku university, Japan) Metallurgy School University of Science and Technology Beijing Beijing 100083 China institute for Chemical Reaction science Tohoku University Japan

A comprehensive kinetic model of NO formation during coke combustion in packed-bed in presence of noncombustible particles was developed. The detailed homogeneous gas-phase chemistry (including 102 chemical reactions), heterogeneous gas-solid chemistry (including 11 reactions) of coke combustion and NO formation, and the heat and mass transfer were taken into account in the present model. The governing equations which are strongly coupled, non-linear and unsteady with 26 unknowns in total, were dispersed into differential equations with the finite differential method. Meanwhile, all the differential equations were numerically solved to give the time-histories and space-distributions oftemperatures of the bed and gas phase as well as the concentrations of all the gaseous species. By comparison, the experimental data were explained well by the calculated results. Based on the kinetic and mathematical model, the effects of O2 content of inlet gas, the initial chemical analysis of coke, bed-temperature and local reductive atmosphere (CO/O2) on NO formation during packed-bed coke combustion were numerically discussed. It was found that coke samples with a higher initial content of [N] and volatile matters, combusted under a suitable O2-containing atmosphere produced less NO emission. The reactions between CO and NO, catalyzed by high temperature surface of coke particles may be responsible for efficient reduction of NO.

关键词： kinetic model NO formation combustion packed-bed coke Metallurgy

Probabilistic composition of cone-based cardinal direction relations

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science china(Technological sciences) 2008年第S1期51卷 81-90页

作者： LIU Yu1,TIAN Yuan1 & WENG JingNong2 1 institute of Remote Sensing and Geographical Information Systems,peking university,beijing 100871,china 2 College of Software,Beihang university,beijing 100083,china peking Univ Inst Remote Sensing & Geog Informat Syst Beijing 100871 Peoples R China Beihang Univ Coll Software Beijing 100083 Peoples R China

Composition tables play a significant role in qualitative spatial reasoning (QSR). At present,a couple of composition tables focusing on various spatial relations have been developed in a qualitative approach. However,the spatial reasoning proc-esses are usually not purely qualitative in everyday life,where probability is one important issue that should be considered. In this paper,the probabilistic compo-sitions of cone-based cardinal direction relations (CDR) are discussed and esti-mated by making some assumptions. Consequently,the form of composition result turns to be {(R1,P1),(R2,P2),…,(Rn,Pn)},where Pi is the probability associated with relation Ri. Employing the area integral method,the probabilities in each composi-tion case can be computed with the assumption that the target object is uniformly distributed in the corresponding cone regions.

关键词： spatial reasoning cardinal direction relations probabilistic composition

AutoSyn:A new approach to automated synthesis of composite web services with correctness guarantee

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science in china(Series F) 2009年第9期52卷 1534-1549页

作者： HUAI JinPeng1,2,DENG Ting1,2,LI XianXian1,2,DU ZongXia1,2 & GUO HuiPeng1,2 1 National Laboratory of Software Development Environment,Beihang university,beijing 100191,china 2 School of Computer science & Engineering,Beihang university,beijing 100191,china National Laboratory of Software Development Environment Beihang University Beijing 100191 China School of Computer science & Engineering Beihang University Beijing 100191 China

How to compose existing web services automatically and to guarantee the correctness of the design （e.g. freeness of deadlock and unspecified reception, and temporal constraints） is an important and challenging problem in web services. Most existing approaches require a detailed specification of the desired behaviors of a composite service beforehand and then perform certain formal verification to guarantee the correctness of the design, which makes the composition process both complex and time-consuming. In this paper, we propose a novel approach, referred to as AutoSyn to compose web services, where the correctness is guaranteed in the synthesis process. For a given set of services, a composite service is automatically constructed based on L＊ algorithm, which guarantees that the composite service is the most general way of coordinating services so that the correctness is ensured. We show the soundness and completeness of our solution and give a set of optimization techniques for reducing the time consumption. We have implemented a prototype system of AutoSyn and evaluated the effectiveness and efficiency of AutoSyn through an experimental study.

关键词： business protocol synthesis composite service correctness constraints L* algorithm

The formation depth of coesite-bearing eclogite,Dabie UHPM zone,china,modified by tectono-original additional hydrostatic pressure

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Chinese science Bulletin 1999年第5期44卷 398-411页

作者： LU Guxian, CHEN Jing, LIU Ruixun and LI Xiaobo institute of Geomechanics , beijing 100081, china Electron Microscopy Laboratory, peking university, beijing 100871, china Department of Geology, peking university, beijing 100871, china institute of Geological Information , beijing 100037, china institute of Geomechanics Beijing China Electron Microscopy Laboratory Peking University Beijing China Department of Geology Peking University Beijing China institute of Gelogical Information Beijing China

The knowledge that hydrostatic pressure is equal to the gravity value of the overlying rocks in studying a dynamic state of certain underground site is argued. It is suggested that the stress field T in the crust is a combination or superposition of total hydrostatic pressure P with differential stress σ,and the total hydrostatic pressure P at any point in the crust comprises two parts: one is spherical stress tensor PG caused by the gravity, and the other is spherical stress tensor Ps caused by tectonic stress; therefore P could not be attributed to the gravity of overlying rocks only. The results obtained by a finite-element simulation indicate that the tectono-original additional hydrostatic pressures Ps decrease gradually from the compressive zone （pcS） to the shear zone (PSHs)and to the tensile zone （PTs）, i.e.Pcs>PsHs>PTs in the same depth. On the basis of the above-mentioned research, the method of measurement and calculation of metallogenetic depth corrected by Ps is

关键词： formation depth tectonic additional hydrostatic pressure Dabie UHPM zone coesite-bearing eclogite expansion-cracking texture tectonic physicochemistry.

On Catastrophe and Cavitation for SphericalCavity

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Communications in Nonlinear science and Numerical Simulation 1999年第4期4卷 249-254页

作者： Ming JIN Kefu HUANG Jike WU(Department of Mechanics and Engineering science, peking university, beijing 100871,china) Department of Mechanics and Engineering science Peking University Beijing 100871 China

IntroductionInrecelltyears,theresearchesoncavitationandcatastropheofacavitysu***therwithbifllrcationtheory... 详细信息

IntroductionInrecelltyears,theresearchesoncavitationandcatastropheofacavitysu***therwithbifllrcationtheory...

关键词： nonlinearity bifurcation Hooke material