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Application and Comparison of Two SGS Models in Large Eddy Simulation of FreeTurbulent Jet Flow

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Communications in Nonlinear science and Numerical Simulation 1999年第1期4卷 12-19页

作者： Hong YAN and Mingde SU (department of engineering Mechanics, tsinghua university, beijing 100084, china) department of engineering Mechanics Tsinghua University Beijing 100084 China

Large eddy simulations of spatially evolved turbulent round jets were presented. The two SGS models called the standard Smagorinsky’s eddy viscosity model and the non-eddy viscosity stimulated small scale(SSS) model developed by Shah & Ferziger were applied. The Reynolds number of the flow was taken as 10000 based on the orifice diameter and the axial velocity in the orifice. The comparison between these two models showed that the standard Smagorinsky’s viscosity model with Smagorinsky’s constant of 0.1 underestimated the turbulent intensity, while the SSS model showed a better agreement with the experiment. Also the SSS model was used to investigate the development of vortex. The convective boundary condition at the outflow boundary was adopted to ensure less effect of noise on the upstream.

关键词： stimulated small scale model smagorinsky’s eddy viscosity model Round jet, Large eddy simulation

ATP as anindicator of biomass activity in thermophilic upflow anaerobic sludge blanket reactor

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Journal of environmental sciences 2000年第3期12卷 380-384页

作者： CHEN Hong (department of environmental science and engineering ,Zhejiang university ,Hangzhou 31 0 0 2 7,china) 浙江大学浙江杭州 3 1 0 0 2

Thisworkinvestigatedthebiomassactivityinathermophilicupflowanaerobicsludgeblanket (UASB )reactorof wastewatertreatment .SynthetictextilewastewaterwithpH 1 0— 1 1 ,CODlevelof2 0 0 0— 30 0 0mg/Lwastested .Cellularadenosine triphosphate (ATP)involatilesolids (VS ;mgATP/gVS)wasmeasuredandexpressedasspecificATPcontenttocomparethe biomassactivityinupzoneandlowerzoneinUASBreactor .TheresultshowsthatthespecificATPcontentbasedontotalvolatile solids (VS)inlowerzone ( 0 .0 4 6mgATP/gVSaverage)ismuchlowerthanthatinupzone ( 0 .62mgATP/gVSaverage)duetohighcontentofinactivebiomassandhighpHinlowerzone .TheSATPinupzoneincreasesasHRTincreasesandapproachestoa maximumvalueof 0 .85mgATP/gVSatHRTof 7h ,thendecreases .ItshowsmostofthetotalVSinupzonerepresentactive bacterialbiomassatHRTof 7h .Rateofsubtractutiliz*** effectofHRTonSATPinlowerzoneisnotassignificantasonSATPinupzone .ThebuffercapacityofthethermophilicUASB reactorisverygood .ItistheactivityofsludgegranulesinlowerzonethatgivetheUASBreactorsuchagoodbuffercapacitytotheinlethighpH .

关键词： ATP biomassactivity UASBreactor

INFLUENCES OF ACID POST-TREATMENT ON THE MORPHOLOGY OF SOAP-FREE P(MMA-EA-MAA)PARTICLES PREPARED BY SEEDED EMULSION POLYMERIZATION

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Chinese Journal of Polymer science 2005年第5期23卷 479-485页

作者： Kai Kang Cheng-you Kan Yi Du De-shan Liu department of Chemical engineering,School of Materials science and engineering,tsinghua university,beijing 100084,china department of Chemical engineering School of Materials Science and Engineering Tsinghua University Beijing 100084 China

Soap-free poly（methyl methacrylate-ethyl acrylate-methacrylic acid） latex particles with narrow size distribution were synthesized by seeded emulsion polymerization, and the porous particles were created by a stepwise alkali/acid treatment method. Effects of acid treatment conditions on the particle morphology were investigated. Results show that one to three pores were formed inside most of particles after post-treatment. At pH 7.0, when the treatment temperature was lower than 70℃, the size of particles and the volume of pores remained almost unchanged, and these two values increased significantly when the temperature was higher than 70℃. Both the particle size and the pore volume decreased with the increase of initial pH value and treatment time in the acid treatment. As the pH was below 4.0 and the treatment time was longer than 180 min, the particles shrunk in size.

关键词： Soap-free emulsion polymerization Particle morphology Porous structure Acid treatment Methyl methacrylate based copolymer.

INTERFACIAL REACTIONS OF METAL FILMS WITH AlN SUBSTRATE

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中国有色金属学会会刊：英文版 1996年第2期6卷 81-85页

作者： He Xiangjun Tao Kun Fan Yudian (department of Materials science and engineering, tsinghua university, beijing 100084) department of Materials science and engineering Tsinghua University Beijing 100084 China

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关键词： thin films interfacial reactions AlN substrate

A measure for spatial heterogeneity of vegetation in the Center of Inner Mongolia

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Progress in Natural science:Materials International 2008年第3期18卷 289-295页

作者： Baimin Songa,b, Daming Huangc,d, Renqing Wanga, Shiyomi Masae d, Fei Xua, Wei Wanga, Gaosheng Zhanga, Xianqiang Zhanga, Jian Qiaoe a College of Life science, Shandong university, Jinan 250100, china b department of environmental science and engineering, tsinghua university, beijing 100084, china c Institute of Ecology, department of Biological sciences and Biotechnology, tsinghua university, beijing 100084, china d Faculty of science, Ibaraki university, Bunkyo 2-1-1, Mito 310-8512, Japan e department of Chemical engineering, tsinghua university, beijing 100084, china College of Life science Shandong University Jinan 250100 China department of environmental science and engineering Tsinghua University Beijing 100084 China Institute of Ecology Department of Biological Sciences and Biotechnology Tsinghua University Beijing 100084 China Faculty of science Ibaraki University Bunkyo 2-1-1 Mito 310-8512 Japan department of Chemical engineering Tsinghua University Beijing 100084 China

This study surveyed and analyzed the vegetation heterogeneity in the Center of Inner Mongolia (CIM) by a new method based on the beta-binomial distribution for each kind of vegetation. As many as 190 large quadrats of 5 mm 5 mm (representing an area of 50 km 50 km) (referred to as L-quadrats hereafter) were extracted from about an area of 475,000 km2. Each L-quadrat was divided into four small quadrats (S-quadrat) of 2.5 mm 2.5 mm (equivalent to 25 km 25 km) and the frequency of occurrence of each type of vegetation was recorded in each small quadrate. The weighted average heterogeneity from all of the vegetations composing a land- scape provides a measure at landscape level to determine the spatial intricateness of landscape composition. Our results indicated that each vegetation has its own distribution pattern and the degree of heterogeneity is different from one kind of vegetation to the other. The results proved that the beta-binomial distribution can be very useful for analyzing vegetation landscapes.

关键词： Heterogeneity Beta-binomial distribution Frequency Occurrence Inner Mongolia

Prediction and Control of both Wrinkle Limit and Fracture Limiton Cylindrical Cup Deep-drawing(Ⅱ)

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International Journal of Minerals,Metallurgy and Materials 1999年第3期13卷 201-204页

作者： Junxiang Lei Yonglin Kang(department of Mechanical engineering, Yantai university, Yantai 264005, china)(Material science and engineering School, university of science and Technology beijing, beijing 100083, china) department of Mechanical engineering Yantai University Yantai 264005 China Material science and engineering School University of Science and Technology Beijing Beijing 100083 China

The prediction and control criterion of both the wrinkle limit and fracture limit on the cylindrical cup deep-drawing are given, and the prediction and control diagram of both the wrinkle limit and fracture limit are also given. The results show that it is suitable for no-flange cylindrical cup deep-drawing, narrow-flange cylindrical cup deep-drawing, wide-flange cylindrical cup deep-drawing/expanding compound forming and rigid punch expanding forming.

关键词： cylindrical cup wrinkle limit fracture limit deep-drawing expanding forming compound forming

An overview on industrial waste management in china

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Journal of environmental sciences 1996年第3期8卷 313-320页

作者： Yang Yanru Nie Yongfeng Li Guoding(department of environmental engineering, tsinghua university, beijing 100084,china) Dept. of environmental engineering Tsinghua University Beijing 100084 China

The article is a summary of the industrial waste management in china during the recent *** overall description of industrial waste was given from generation; treatment, disposal and emission and comprehensive utilization. In spite of the serious situation of industrial waste,china has realized it and made great progress in establishing corresponding legislation system, taking a series of administrative measures and developing effective treatment and disposal ***, there still exist many problems , and it is of great urgency to take countermeasures in industrial waste management.

关键词： industrial waste management china

Building a next generation Internet with source address validation architecture

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science in china(Series F) 2008年第11期51卷 1681-1691页

作者： WU JianPing1,3,REN Gang1,3 & LI Xing2,3 1 department of Computer science,tsinghua university,beijing 100084,china 2 department of Electronic engineering,tsinghua university,beijing 100084,china 3 tsinghua National Laboratory for Information science and Technology(TNList) ,beijing 100084,china department of Computer science Tsinghua University Beijing China tsinghua National Laboratory for Information science and Technology (TNList) Beijing China department of Electronic engineering Tsinghua University Beijing China

The IP packet forwarding of current Internet is mainly destination based. In the forwarding process, the source IP address is not checked in most *** causes serious security, management and accounting problems. Based on the drastically increased IPv6 address space, a ＂source address validation architecture＂（SAVA） is proposed in this paper, which can guarantee that every packet received and forwarded holds an authenticated source IP address. The design goals of the architecture are lightweight, loose coupling, ＂multi-fence support＂ and incremental deployment. This paper discusses the design and implementation for the architecture, including inter-AS, intra-AS and local subnet. The performance and scalability of SAVA are described. This architecture is deployed into the CNGI-CERNET2 infrastructure a large-scale native IPv6 backbone network of the china Next Generation Internet project. We believe that the SAVA will help the transition to a new, more secure and dependable Internet.

关键词： IP source address validation network architecture network security

An introduction to tsinghua Cloud

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science china(Information sciences) 2010年第7期53卷 1481-1486页

作者： ZHENG WeiMin1,2 1department of Computer science and Technology, tsinghua university, beijing 100084, china 2tsinghua National Laboratory for Information science and Technology, beijing 100084, china department of Computer science and Technology Tsinghua University Beijing China tsinghua National Laboratory for Information science and Technology Beijing China

Cloud computing has become a trend that draws attention from both academia and industry all over the world. This paper unveils details of tsinghua Cloud, a comprehensive solution for cloud computing developed by Tsing... 详细信息

关键词： cloud computing distributed file system virtual computing environment data sharing