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Numerical simulation of channel pattern changes Part Ⅱ:Application in a conceptual channel

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International Journal of Sediment research 2010年第4期25卷 380-390页

作者： Hong WAng1, Gang ZHOU2, and Xuejun SHAO31 Ph.D., Associate Professor, State Key Laboratory of Hydroscience and Engineering, tsinghua university, beij.ng 100084, china. 2 Graduate student for a Ph.D. degree (at the time of this research work), State Key Laboratory of Hydroscience and Engineering, tsinghua university, beij.ng 100084, china. Presently: Post-doctoral research fellow, Chinese research Academy of Environmental Sciences, beij.ng 100012, china 3 Ph.D., Professor, State Key Laboratory of Hydroscience and Engineering, tsinghua university, beij.ng 100084, china. Ph.D. Associate Professor State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China Graduate student for a Ph.D. degree (at the time of this research work) State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China. Presently: Post-doctoral research fellow Chinese Research Academy of Environmental Sciences Beijing 100012 China Ph.D. Professor State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China

This paper presents simulated channel patterns for various scenarios in a conceptual alluvial valley by an improved two-dimensional (2-D) mathematical model described in the companion paper. Starting from the same initial channel, different channel patterns have been simulated over a real time period of 250 days for varied boundary and initial conditions, including the inlet water discharge and sediment load, initial valley slope, and erodibility of river banks. Impacts of these control factors are discussed, in terms of the longitudinal bottom profiles of simulated fluvial channels, the geometry of channel cross sections, and the water surface profiles in the conceptual river valley. Results suggest that the upper and lower parts of the same channel may have different planforms because the sediment transport conditions of the two parts differ greatly. Simulated causal relationship between control variables and channel patterns agrees qualitatively with known channel pattern theories.

关键词： Channel pattern changes Numerical simulation Resistance to bank erosion Sediment transport Braided channel

Local Gromov-Witten invariants of canonical line bundles of toric surfaces

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Science china Mathematics 2010年第6期53卷 1571-1582页

作者： YAng Fei & ZHOU Jian Department of Mathematical Sciences,tsinghua university,beij.ng 100084,china 1. Department of Mathematical Sciences Tsinghua University Beijing 100084 China

We define and compute by localizating the local equivariant Gromov-Witten invariants of the canonical line bundles of toric surfaces,not necessarily Fano.

关键词： local Gromov-Witten invariants localization partition function geometric engineering

DEVELOPMENT OF STEP-POOL SEQUENCE AND ITS EFFECTS IN RESISTANCE AND STREAM BED STABILITY

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International Journal of Sediment research 2004年第3期19卷 161-171页

作者： Zhao-Yin WAng, Jiang XU and Changzhi LI Professor, Dept. of Hydraulic Engineering, tsinghua university, beij.ng & Chairman of Advisory Council, International research and Training center on Erosion and Sedimentation, 100084, china, Email: zywang@***.M. Phil., Dr. & Post Doctorate research fellow, Dept. of Hydraulic Engineering, tsinghua university, beij.ng, 100084, china Dept. of Hydraulic Engineering Tsinghua University Beijing & Chairman of Advisory Council International Research and Training Center on Erosion and Sedimentation 100084 China Dr. & Post Doctorate research fellow Dept. of Hydraulic Engineering Tsinghua University Beijing 100084 China

Experiments were conducted and field investigations were performed to study the development of step-pool sequence and its effects on resistance to the flow and stream bed stability. Step-pool sequence develops in incised channels as a result of streambed erosion, which is compared with sand dunes and armor layer of the role in resistance and streambed protection. The tight interlocking of particles in steps gives them an inherent stability which only extreme floods are likely to disturb. That stability suggests that step-pools are a valid equilibrium form, especially when coupled with their apparent regularity form and their role in satisfying the extreme condition of resistance maximization. The development degree of step-pools, SP, is proportional to the streambed slope. If the incoming sediment load is equal to or more than the sediment-carrying capacity of the flow, there is no bed erosion and thence there are no step-pools. If the flow depth increases and is over the step-height the resistance caus

关键词： Step-pool Streambed stability Erosion Resistance Rate of energy dissipation Manning’s roughness n

Local segment-shared protection based on source egress gateway selection for multi-domain optical mesh networks

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Science china(Information Sciences) 2011年第2期54卷 227-235页

作者： ZHAng ShengFeng1,3, PEng YunFeng1,2, DU Shu1, YAng XiaoLong1,2 & LOng KePing1,2 1research center for Optical Internet and Mobile Information networks, university of Electronic Science and Technology of china, Chengdu 611731, china 2Institute of Advanced network Technology and New Serives (ANTS), university of Science and Technology beij.ng, beij.ng 100083, china 3research center for Optical Internet networks, Chongqing university of Posts and Telecommunications, Chongqing 400065, china 1. research center for Optical Internet and Mobile Information networks University of Electronic Science and Technology of China Chengdu 611731 China3. Research Center for Optical Internet Networks Chongqing University of Posts and Telecommunications Chongqing 400065 China2. Institute of Advanced Network Technology and New Serives (ANTS) University of Science and Technology Beijing Beijing 100083 China

Survivability for multi-domain optical networks is becoming a key parameter due to expanding network. In order to provide the shared-path-protected lightpath in multi-domain optical mesh networks, we propose a protection solution, called GSLSSP. A new source egress gateway selecting mechanism is adopted in this solution. For each connection request, this mechanism can enable the source node to select a better egress gateway node to the destination domain and compute one inter-domain working path near the optimal path with the cooperating of this gateway node, under scalability and domain privacy constraint of multi-domain networks. And then one intra-domain link-disjoint local segment-backup path for each working-segment path is computed out in each single-domain passed by the working path. Simulation evaluation shows that the proposed scheme can provide 100% protection ability for multiple failures. Besides, it is effective in multi-domain path protection with more efficient resource utilization, lower blocking probabilities and less inter-domain cost than other schemes.

关键词： survivability optical mesh networks multi-domains multiple failures segment-shared protection

A multiphase mesostructure mechanics approach to the study of the fracture-damage behavior of concrete

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Science china(Technological Sciences) 2008年第S2期51卷 8-24页

作者： TAng XinWei1,ZHAng ChuHan1 & SHI JianJun2 1 State Key Laboratory of Hydroscience and Engineering,tsinghua university,beij.ng 100084,china 2 Department of Urban Construction,Nanhua university,Hengyang 421001,china 1. State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China 2. Department of Urban Construction Nanhua University Hengyang 421001 China

A multiphase mesostructure mechanical model is proposed to study the deformation and failure process of concrete considering its heterogeneity at the meso scopic ***,concrete is taken as a type of three-component composite material composed of mortar matrix,aggregates and interfaces on the ***,an efficient approach to the disposition of aggregates of concrete and a state matrix method to generate mesh coordinates for aggregates are ***,based on the nonlinear continuum damage mechanics,a meso-scale finite element model is presented with damage softening stress-strain relationship for describing the mechanical behavior of different components of *** this method,heterogeneities of each component in the concrete are considered by assuming the material properties of three components conform to the Weibull distribution ***,based on this multiphase meso-mechanics model,a simulation analysis of fracture behavior of a rock-fill concrete(RFC) beam is *** study includes experimental tests for determining basic mechanical parameters of three components of RFC and four-point flexural beam tests for verification of the *** is preliminarily shown that the numerical model is applicable to studying failure mechanisms and process of concrete type material.

关键词： concrete multiphase mesostructure mechanics numerical simulation experimental research

A quantification model for apoptosis in mouse embryos in the early stage of fetation

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Science china(Life Sciences) 2009年第10期52卷 922-927页

作者： WAng PengFei1, FU JianHua1, MA WanYun1, CHEN DieYan1, Lü DanYu2 & BAI WenJia3 1 Key Laboratory for Atomic and Molecular Nanosciences of Education Ministry, Department of Physics, tsinghua university, beij.ng 100084, china 2 Department of Anatomy & Histology and Embryology, School of Basic Medical Sciences Peking university Health Science center, beij.ng 100083, china 3 Department of Automation, tsinghua university, beij.ng 100084, china 1. Key Laboratory for Atomic and Molecular Nanosciences of Education Ministry Department of Physics Tsinghua University Beijing 100084 China 2. Department of Anatomy & Histology and Embryology School of Basic Medical Sciences Peking University Health Science Center Beijing 100083 China 3. Department of Automation Tsinghua University Beijing 100084 China

Apoptosis is the most important inducement and modulator for embryos in the early stage of fetation, i.e. after the 8-cell stage, mostly the morula and blastula stage, to proceed to the stage of nonlinear development. Using a two-photon laser scanning microscopy (TPLSM) system, we obtained 3-dimensional (3D) fluorescent images of preimplantation mouse embryos. A model for quantification was established. The statistical results for the spatial location of apoptosis bodies in embryos was obtained following image processing, as well as investigation of the kinetics of apoptosis. It was found that most (70%) apoptosis occurred in the trophectoderm, and the departure between the centroid and geometric center of embryos had a step transition when embryos developed into the 32-cell stage, which was consistent with the theoretical prediction that the blastocele would induce a symmetry break of the distribution of cells in embryos.

关键词： apoptosis preimplantation mouse embryo TPLSM quantification model

Molecular dynamics simulation of kink in 〈100〉 edge dislocation in body centred cubic iron

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Chinese Science Bulletin 2007年第16期52卷 2291-2296页

作者： CHEN LiQun1,2,WAng ChongYu2,3,4 & YU Tao2 1 College of Sciences,Central South university of Forestry & Technology,Changsha 410004,china 2 Central Iron and Steel research Institute,beij.ng 100081,china 3 Department of Physics,tsinghua university,beij.ng 100084,china 4 International center for Materials Physics,Chinese Academy of Sciences,Shenyang 110016,china College of Sciences Central South University of Forestry and Technology Changsha 410004 China

Using the molecular dynamics method,we have constructed two kink models corresponding to the 〈100〉{010} and 〈100〉{011} edge dislocations (EDs) in body centred cubic (bcc) Fe. It is found that the geometric structure of a kink depends on the type of edge dislocation and the structural energies of the atoms sites in the dislocation core region. The formation energies,migration energies and widths of the kinks in different types of EDs are calculated. The results show that formation and migration of the kink in the 〈100〉{010} edge dislocation are difficult. The 〈100〉{011} edge dislocation moves primarily through kink nucleation,rather than kink migration.

关键词：分子动力学边缘位移铁纽结结构

An analysis of seismic attenuation in random porous media

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Science china(Physics,Mechanics & Astronomy) 2010年第4期53卷 628-637页

作者： LIU Jiong1, BA Jing2, MA JianWei1 & YAng HuiZhu1 1 Institute of Seismic Exploration, School of Aerospace, tsinghua university, beij.ng 100084, china 2 research Institute of Petroleum Exploration & Development, Petrochina, beij.ng 100083, china 1. Institute of Seismic Exploration School of Aerospace Tsinghua University Beijing 100084 China2. Research Institute of Petroleum Exploration & Development PetroChina Beijing 100083 China

The attenuation of seismic wave in rocks has been one of the interesting research topics, but till now no poroelasticity models can thoroughly explain the strong attenuation of wave in rocks. In this paper, a random porous medium model is designed to study the law of wave propagation in complex rocks based on the theory of Biot poroelasticity and the general theory of stochastic process. This model sets the density of grain, porosity, permeability and modulus of frame as random parameters in space, and only one fluid infiltrates in rocks for the sake of better simulation effect in line with real rocks in earth strata. Numerical simulations are implemented. Two different inverse quality factors of fast P-wave are obtained by different methods to assess attenuation through records of virtual detectors in wave field (One is amplitude decay method in time domain and the other is spectral ratio method in frequency domain). Comparing the attenuation results of random porous medium with those of homogeneous porous medium, we conclude that the attenuation of seismic wave of homogeneous porous medium is far weaker than that of random porous medium. In random porous media, the higher heterogeneous level is, the stronger the attenuation becomes, and when heterogeneity σ = 0.15 in simulation, the attenuation result is consistent with that by actual observation. Since the central frequency (50 Hz) of source in numerical simulation is in earthquake band, the numerical results prove that heterogeneous porous structure is one of the important factors causing strong attenuation in real stratum at intermediate and low frequency.

关键词： the theory of stochastic process the theory of Biot poroelasticity the attenuation of seismic wave inverse quality factor

Design of CERNET2-One of the Core networks in CngI

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ZTE Communications 2005年第4期3卷 11-16页

作者： Wu Jianping, Li Xing, Li Chongrong (china Education and research network center, tsinghua university, beij.ng 100084, china)

This article presents the network design schemes of CERNET2 including overall architecture, the backbone, core nodes, access solutions and the CngI peer centers. CERNET2 connects 25 core nodes distributed in 20 cities of china at the speed of 2.5-10 Gb/s. CERNET2 has four unique features. First, its backbone adopts native IPv6 protocols, rather than IPv4/IPv6 dual stack. It is the largest pure IPv6 network in the world. Second, it provides an environment for testing and trial operation of china-made IPv6 core routers. It also allows tests of interconnection, interworking and interoperation among multiple vendors. Third, the large IPv6 address space enables the study on network addresses in a real network environment, which ensures the construction of a secured and trusted CngI. Last, it is a test-bed for ngI applications.

关键词： CERNET Design of CERNET2-One of the Core networks in CngI Core