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PRINCIPLES OF RIVER TRAINING AND MANAGEMENT

International Journal of Sediment Research 2007年第4期22卷 247-262页

作者： Zhaoyin WANG1, Shimin TIAN2, Yujun YI3, and Guoan YU4 1 Prof., state key laboratory of Hydroscience and Engineering, tsinghua university, beijing, 100084, china 2 Ph. D., china Institute of Water Resources and Hydro-Power Research, beijing 100044, china. 3 Ph. D., state key laboratory of Hydroscience and Engineering, tsinghua university, beijing, 100084, china 4 Ph. D., state key laboratory of Hydroscience and Engineering, tsinghua university, beijing, 100084, china tsinghua Univ State Key Lab Hydrosci & Engn Beijing 100084 Peoples R China china Inst Water Resources & Hydropower Res Beijing 100044 Peoples R China

River regulation and river training have been performed for various purposes and negative effects have been shown in numerous cases. In some cases the negative effects are so serious that humans have to consider to "renaturalize" the regulated rivers. Only by using the strategy of integrated river management the diverse river uses and natural fluvial processes and ecological systems may be harmonized. Based on analysis of case studies and data collected from literatures this paper presents the concept of integrated river management and four principles of river training. The integrated river management comprises: 1) taking the watershed, upper stream basin including the tributaries, middle and lower reaches and the estuary as an integrated entity in the planning, design and management; and 2) mitigating or controlling the negative impacts on hydrology, erosion and sedimentation, fluvial processes, land use and river use, environment and ecology while in achieving economic benefit from water resources development, flood safety management and hydropower exploitation. River training and management should be in accordance with the four principles: 1) extending the duration of river water flowing on the continent, which may be achieved by extending the river course or reducing the flow velocity; 2) controlling various patterns of erosions and reducing the sediment transportation in the rivers; 3) increasing the diversity of habitat and enhancing the connectivity between the river and riparian waters; and 4) restoring natural landscapes.

关键词： River training Integrated river management Sediment Erosion control Ecological and landscape restoration

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Multi-dimensional project management models for mega-construction companies and their applications

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Science china(Technological sciences) 2011年第S1期54卷 118-124页

作者： LIN ZhengHang 1,2,QIANG MaoShan 1,2,TANG WenZhe 1,2,FAN QiXiang 3 &LIU Qiang 4 1 Institute of Project Management and Construction Technology,tsinghua university,beijing 100084,china 2 state key laboratory of Hydraulic and Engineering,tsinghua university,beijing 100084,china 3 china Three Gorges Corporation,Yichang 443002,china 4 school of Software,tsinghua university,beijing 100084,china 1. Institute of Project Management and Construction Technology Tsinghua University Beijing 100084 China2. State Key Laboratory of Hydraulic and Engineering Tsinghua University Beijing 100084 China3. China Three Gorges Corporation Yichang 443002 China4. School of Software Tsinghua University Beijing 100084 China

china is undertaking an increasing number of mega-infrastructure projects along with its rapid economic *** participants in these projects,understand how to adapt the proper and efficient management strategies is *** this paper,we propose three distinct models for companies under various background and management requirements,based on sophisticated data analysis and model ***,we successfully committed these models with hydropower development projects and achieved a great progress in enhancing management efficiency.

关键词： project management models mega-construction companies applications hydropower development companies

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Aging assessment of large generator insulation based on PD measurements

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Progress in Natural Science:Materials International 2005年第11期15卷 1035-1043页

作者： YUE Bo, CHEN Xiaolin, CHENG Yonghong and XIE Hengkun (state key laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong university, Xi'an 710049, china Graduate school at Shenzhen, tsinghua university, Shenzhen 518055, china Department of Electrical Engineering, tsinghua university, beijing 100084, china) state key laboratory of Electrical Insulation and Power Equipment Xi''an Jiaotong University Xi''an 710049 China. Graduate school Shenzhen Tsinghua University Shenzhen 518055 China. Department of Electrical Engineering Tsinghua University Beijing 100084 China

The statistical parameters of phase resolved partial discharge (PD) distribution and ultra-wideband (UWB) characteristics of PD pulse are proposed for aging assessment of large generator insulation. Multi-stress aging tests of the model generator stator bar specimens were performed and PD measurements were conducted using both digital PD detector with frequency ranging from 40 kHz to 400 kHz and UWB PD detector with bandwidth from 10 MHz to 3 GHz at different aging stages. The test results show that the skewness and UWB frequency characteristics of PD can be taken as the characterization parameters for aging assessment of generator insulation. Furthermore, the measurement results of real generator stator bars show that these methods based on statistical parameters and UWB characteristics of PD are prospective for aging assessment and residual lifetime estimation of large generator stator insulation.

关键词： partial discharge stator insulation multi-stress accelerated aging statistical parameters ultra-wideband aging assessment.

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Numerical exploration of new features on three-dimensional transition of a cylinder wake

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Science china Mathematics 2004年第z1期47卷 69-80页

作者： LING Guocan, XIONG Jun & ZHU Keqinstate key laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of sciences, beijing 100080, china Department of Engineering Mechanics, tsinghua university, beijing 100084, china Chinese Acad Sci Inst Mech State Key Lab Nonlinear Mech Beijing 100080 Peoples R China Tsing Hua Univ Dept Engn Mech Beijing 100084 Peoples R China

The three-dimensional transition of the wake flow behind a circular cylinder is studied in detail by direct numerical simulations using 3D incompressible N-S equations for Reynolds number ranging from 200 to 300. New features and vortex dynamics of the 3D transition of the wake are found and investigated. At Re = 200, the flow pattern is characterized by mode A instability. However, the spanwise characteristic length of the cylinder determines the transition features. Particularly for the specific spanwise characteristic length linear stable mode may dominate the wake in place of mode A and determine the spanwise phase difference of the primary vortices shedding. At Re = 250 and 300 it is found that the streamwise vortices evolve into a new type of mode "dual vortex pair mode" downstream. The streamwise vortex structures switch among mode A, mode B and dual vortex pair mode from near wake to downstream wake. At Re = 250, an independent low frequency fm in addition to the vortex shedding frequency fs is identified. Frequency coupling between fm and fs occurs. These result in the irregularity of the temporal signals and become a key feature in the transition of the wake. Based on the formation analysis of the streamwise vorticity in the vicinity of cylinder, it is suggested that mode A is caused by the emergence of the spanwise velocity due to three dimensionality of the incoming flow past the cylinder. Energy distribution on various wave numbers and the frequency variation in the wake are also described.

关键词： cylinder, wake, 3D transition, Fourier-spectral-spectral-element method, direct numerical simulation (DNS).

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Lightning electromagnetic field generated by grounding electrode considering soil ionization

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Progress in Natural Science:Materials International 2006年第9期16卷 1002-1006页

作者： ZENG Rong , HE Jinliang, ZHANG Bo and GAO Yanqing (state key laboratory of Power Systems, Department of Electrical Engineering, tsinghua university, beijing 100084, china) state key laboratory of Power Systems Department of Electrical Engineering Tsinghua University Beijing 100084 China

A circuit model with lumped time-variable parameter is proposed to calculate the transient characteristic of grounding electrode under lightning current, which takes into consideration the dynamic and nonlinear effect of soil ionization around the grounding electrode. The ionization phenomena in the soil are simulated by means of time-variable parameters under appropriate conditions. The generated electromagnetic field in the air is analyzed by using electrical dipole theory and image theory when the lightning current flows into the grounding electrode. The influence of soil ionization on the electromagnetic field is investigated.

关键词： electromagnetic field grounding electrode soil ionization transient characteristic.

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Effect of incoming sediment on the transport rate of bed load in mountain streams

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International Journal of Sediment Research 2009年第3期24卷 260-273页

作者： Guo-An YU1, Zhao-Yin WANG2, Kang ZHANG3, Tung-Chiung CHANG4, and Huaixiang LIU51 Dr., Institute of Geographical sciences and Natural Resources Research, Chinese Academy of sciences, beijing 100101, china and Dept. of Hydraulic Engineering, tsinghua university, 2 Prof., state key laboratory of Hydroscience and Engineering, tsinghua university, beijing 100101, china, 3 Ph.D. candidate, state key laboratory of Hydroscience and Engineering, tsinghua university, beijing 100084, china 4 Ph.D. candidate, tsinghua university, beijing 100084, china and Prof., Kaoyuan university, Kaohsiung 82151, Taiwan, china 5 Dr., state key laboratory of Hydroscience and Engineering, tsinghua university, beijing 100084, china [a] Dr. Institute of Geographical sciences and Natural Resources Research Chinese Academy of sciences beijing 100101 china and Dept. of Hydraulic Engineering tsinghua university [b] Prof. state key laboratory of Hydroscience and Engineering tsinghua university beijing 100101 china [c] Ph.D. candidate state key laboratory of Hydroscience and Engineering tsinghua university beijing 100084 china [d] Ph.D. candidate tsinghua university beijing 100084 china and Prof. Kaoyuan university Kaohsiung 82151 Taiwan china [e] Dr. state key laboratory of Hydroscience and Engineering tsinghua university beijing 100084 china

Field experiments were conducted on bed load transport in the Diaoga River, a mountain stream in southwest china, to study the variation of bed load transport with varying sediment supply. The rate of bed load transport is greatly affected by incoming sediment (load and size). Under the same flow conditions, bed load transport rates may differ by three orders of magnitude depending on whether measurements were taken before or after the first flood of the year. The relation of the "bed load transport rate versus flow intensity" appears to have similar characteristics as a clockwise looped-rating curve. Experiments also were conducted during the non-flood season to study bed load transport processes with different incoming load from an upstream section. Bed load with different sizes can be grouped into two types: traveling bed load and structural bed load. Traveling bed load is composed of sediment finer than a critical size, Dc, and its transport rate depends mainly on the incoming sediment rate. The incoming sediment rate can alter the rate of bed load transport by three orders of magnitude. Structural bed load is composed of coarser sediment and its transport rate closely relies on the flow intensity.

关键词： Mountain streams Bed load transport Sediment supply Sediment size distribution

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Microstructures and characteristics of deep trap levels in ZnO varistors doped with Y_2O_3

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Science china(Technological sciences) 2009年第12期52卷 3668-3673页

作者： LIU Jun 1 ,HU Jun 1 ,HE JinLiang 1 ,LIN YuanHua 2 &LONG WangCheng 1 1state key laboratory of Power Systems,Department of Electrical Engineering,tsinghua university,beijing 100084,china 2state key laboratory of New Ceramics and Fine Processing,Department of Material Science and Engineering,tsinghua university, beijing 100084,china 1. state key laboratory of Power Systems Department of Electrical Engineering Tsinghua University Beijing 100084 China 2. state key laboratory of New Ceramics and Fine Processing Department of Material Science and Engineering Tsinghua University Beijing 100084 China

In this paper discussions on ZnO based varistor ceramics doped with different ratios of Y2O3 are *** on the phase and microstructures of the samples indicates that an additional phase is detected in the samples doped with Y2O3,and the average grain size of the specimens decreases from about 9.2μm to 4.5μm,with an increase in the addition of Y2O3 from 0 mol%to 3 mol%.The corresponding varistor’s voltage gradient markedly increases from 462 V/mm to 2340 V/mm,while the nonlinear coefficient decreases from 22.3 to 11.5,***,the characteristics of deep trap levels in these ZnO samples are investigated by measuring their dielectric *** trap energy level and capture cross section evaluated by relaxation peak of the Cole-Cole plot vary slightly as the addition of Y2O3 *** traps may be ascribed to the intrinsic defects of ZnO lattice.

关键词： ZnO varistors Y2O3 electrical properties deep trap levels

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Holographic Storage Parametric Optimization of the Crystal LiNbO3∶Fe Based on One-center Model

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Chinese Journal of Lasers 2002年第1期11卷 28-34页

作者： WANG Jiangang HE Qingsheng JIN Guofan WU Minxian (state key laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments, tsinghua university, beijing 100084, china) Department of Precision Instruments Tsinghua University State Key Laboratory of Precision Measurement Technology and Instruments 北京 100084

Based on one-center model, the effects of the doping amount and the degrees of reduction and oxidation on the dynamic range M, the response time and the photorefractive sensitivity in the crystal LiNbO 3∶Fe are analyzed in detail. The principle of material optimization is discussed. The best crystal thickness (about 1.4～2.6 mm) for the maximum dynamic range M is calculated for the different doping amounts. The results show that the more the doping amount, the lighter the reduction of the crystal should be chosen, and that the heavier the reduction of the crystal, the less effect the doping amount has on the response time. The dynamic range M is in conflict with the response time. Due to the difficulty of processing crystals, the thickness is increased to 5 mm at the cost of decreasing the dynamic range M by 0.3～0.5.

关键词： holographic storage materials parametric optimization LiNbO 3∶Fe crystals

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Magnetism induced by nonmagnetic dopants in zinc-blende SiC: First-principle calculations

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Science china(Physics,Mechanics & Astronomy) 2010年第1期53卷 1-10页

作者： LIU ZhaoQing & NI Jun Department of Physics and key laboratory of Atomic and Molecular Nanoscience (Ministry of Education), tsinghua university, beijing 100084, china 1. Department of Physics and key laboratory of Atomic and Molecular Nanoscience (Ministry of Education) Tsinghua University Beijing 100084 China

Magnetism induced by the nonmagnetic dopants in the zinc-blende SiC (3C-SiC) is investigated by first-principle calculations. The atoms of the first 20 elements in the periodic table except inert gas are used to replace either Si or C atoms as dopants. We find that some nonmagnetic substitutional dopants (mainly the Group IA, Group IIA, Group IIIB, and Group VIIB elements) prefer the spin-polarized ground states with local magnetic moments. In general, the condition for obtaining the local magnetic moments and the magnetic ground state requires that the dopants are p-type and have large electronegativity difference from the neighboring host atoms. The magnetic moments can be tuned over a range between 1 μ B and 3 μ B by doping with the nonmagnetic elements. The nearest-neighbor exchange couplings J 0 between the local magnetic moments are quite large and the codoping method is proposed to increase the dopant concentration. These imply that the nonmagnetic doping in SiC may exhibit collective magnetism. Moreover, the Group IIA Mg and Ca atoms substituting the preferred Si atoms favor the ferromagnetic ground states with the half-metallic electronic properties, which suggests that Mg or Ca substitutional doping on the Si sites in SiC could be a potential route to fabricating the diluted magnetic semiconductors.

关键词： nonmagnetic dopant magnetism SiC diluted magnetic semiconductor first-principle calculation

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Tn5-mutagenesis and identification of atr operon and trpE gene responsible for indole-3-acetic acid synthesis in Azospirillum brasilense Yu62

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Progress in Natural Science:Materials International 2006年第4期16卷 366-372页

作者： XIE Baoen and CHEN Sanfeng state key laboratory for Agrobiotechnology, College of Biological sciences, china Agricultural university, beijing 100094, china state key laboratory for Agrobiotechnology College of Biological Sciences China Agricultural University Beijing 100094 China

To bring more information about synthesis of indole-3-acetic acid (IAA) from Azospirillum brasilense, a Tn5-insertion library of A. brasilense Yu62 was constructed and subjected to screening for IAA producing mutants. Two mutants with decreased IAA levels, named as A3 and A24, were isolated. The sequence analysis of loci tagged showed that the Tn5-1063a was located in the atrA gene encoding GntR family transcriptional regulator and trpE gene encoding component I of anthranilate synthase respectively. At the same time. atrB encoding phosphotransferase and atrC encoding aminotransferase were cloned downstream the atrA gene and atrA, atrB and atrC were clustered in an operon. Mutagenesis and complementation studies showed that atrA and atrC were involved in IAA synthesis. IAA levels of trpE mutant and wild-type strain could be improved by adding anthranilate into the medium.

关键词： indole-3-acetic acid (IAA) IAA mutants Azospirillum brasilense atrABC cluster trpE Tn5 transposon.

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