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A new type of plunge pool―Multi-horizontal submerged jets

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Science China(Technological Sciences) 2008年第12期51卷 2128-2141页

作者： DENG Jun,XU WeiLin,ZHANG JianMing,QU JinXue & YANG YongQuan State Key Laboratory of Hydraulics and Mountain River Engineering,sichuan university,chengdu 610065,China State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan University Chengdu 610065 China

Based on the understanding of the mechanism of energy dissipation,a new type of plunge pool is presented with the advantages of high rate of energy dissipation,low impact pressure,and small close-to-bed velocity on the soleplate of the plunge *** first advantage owes to enlarged shearing energy dissipation areas in the plunge pool,while the other two are caused by the jet that enters in a nearly horizontal level to keep the soleplate from being scoured *** of the above arrangements make this new type of energy dissipator distinct from the underflow energy *** experiments on the physical model,the authors found that the water flow maintained stable and submerged in horizontal direction when the flow was narrow in horizontal but thick in vertical ***,the wide flat nappe was ready to submerge or float as the downstream water level rised or *** entire flow fields of multi-horizontal submerged jets into plunge pool were also numerically *** numerical results of water surface curve,close-to-bed velocity and floor pressure agree well with the experimental *** flow pattern in the plunge pool was analyzed after combining the laboratory data and numerical simulation.

关键词： hydraulic engineering 3-D flow field numerical simulation plunge pool submerged jets

Synthesis mechanism of LiNiVO_4.by wet chemical method and mixed valence of nickel and vanadium

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Chinese Science Bulletin 2002年第6期47卷 454-457页

作者： LAI Qiongyu, LU Jizheng, Jl Xiaoyang, YAN Fangyong, WEI Yongqiang & YU DingChemical college, sichuan university, chengdu 610064. China Analytical and Testing Center, sichuan university, chengdu 610064. China Chemical college Sichuan University Chengdu China Analytical and Testing Center Sichuan University Chengdu China

The single phase LiNiVO4.has been successfully synthesized by adopting a new mild liquid route with oxalic acid as both complexant and precipitant, and this method is named the CPG method. The products were obtained by sintering the dry gel precursor which was prepared by the CPG method at 200-850°C for 2-10 h in air. The products were tested by XRD, XPS, ESR and TGA-DTA, and the results indicate that the single phase LiNiVO4.could be obtained at 4.0°C for 2-3 h in air and LiNiVO4.was still steady at 850°C for 10 h. The valence analyses show that in LiNiVO4.the valence of lithium is +1, both nickel and vanadium have the mixed valence, namely +2, +3 for nickel and +4. +5 for vanadium respectively. The LiNiVO4.can be expressed as LiNi3+xNi2+1-xV4.xV5+1-xO4.(O≤x<1). The pyrolysis mechanism of the dry gel is also discussed.

关键词： LiNiVO4 CPG method dry gel pyrolysis mechanism mixed valence.

Study on bed load transport for uniform sediment in laminar flow

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Science China(Technological Sciences) 2010年第9期53卷 2414-2422页

作者： YANG FengGuang,LIU XingNian,CAO ShuYou,YANG KeJun & HUANG Er State Key Laboratory of Hydraulics and Mountain River Engineering,sichuan university,chengdu 610065,China 1. State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan University Chengdu 610065 China

Previous studies focused on the bed load transport rate for the condition of turbulent flow,while the knowledge of sediment transport in laminar flow is very *** an extreme case to reflect the viscous effect on sediment transport,sediment transport in laminar flow is considered in this *** are at least two factors affecting the transport rate of sediment under laminar flow conditions: (1) fluid forces;(2) particle to particle ***,these two factors represent the physical transport ***,an exposure degree Probability Density Function (PDF) is developed to explore how the transport rate can be associated with characteristics of laminar flow and this factor reflects the particle to particle interactions,and the pickup probability equation in the absence of turbulence is developed based on the stochastic approach which reflects the exposure degree ***,the formulas to calculate the critical shear stress of incipient motion and the bed load transport rate of fine uniform sediment are *** derivation is made mainly based on Einstein’s bed load theory;we choose Einstein’s equation to model this system because we believe that the probabilistic approach taken is an appropriate way to account for the spatial and temporal variations in the forces causing sediment *** formulas have been tested against a wide range of existing laboratory data and compared with other existing empirical or semiempirical *** predictions by these newly proposed formulas are very good.

关键词： exposure degree bed load transport rate pickup probability laminar flow shear stress

Photoabsorption Spectra of Si_n and Si_nO （n ≤ 5）

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Communications in Theoretical phys.cs 2009年第4期 751-755页

作者： AN Fang-Fang~1 ZHANG Hong~(2,+) CHENG Xin-Lu~11 Institute of Atomic and Molecular phys.cs,sichuan university,chengdu {4.,China2 college of physical Science and Technology,sichuan university,chengdu {4.,China Institute of Atomic and Molecular phys.cs Sichuan University Chengdu 610065 China college of physical Science and Technology Sichuan University Chengdu 610065 China

The photoabsorption spectra have been calculated for Si_n and Si_nO（n≤5）clusters using time-dependentdensity-function *** studies suggest that Sin-1O clusters are relatively stable than those of correspondingSi_n ***,substantial differences are observed among the absorption spectra of different molecules in theenergy region（0～8 eV）.Comparing two different exchange-correlation potentials,local-density and generalized-gradientapproximations,both calculated optical spectra present the same spectral feature.

关键词： Si_n clusters Si_nO clusters TDDFT photoabsorption spectra

THREE-DIMENSIONAL TURBULENCE NUMERICAL SIMULATION OF A STEPPED SPILLWAY OVERFLOW

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Journal of Hydrodynamics 2002年第3期14卷 70-75页

作者： Chen Qun college of Hydraulic and Hydroelectric, sichuan university, chengdu 610065, ChinaDai Guang qing State Key Hydraulics Laboratory of High Speed Flows, sichuan university, chengdu 610065, ChinaZhu Fen qing Geotechnic Engineering Co., Second college of Hydraulic and Hydroelectric Sichuan University Chengdu 610065 China State Key Hydraulics Laboratory of High Speed Flows Sichuan University Chengdu 610065 China Geotechnic Engineering Co. Second Survey and Design Institute of Railway Chengdu 610031 China

In this paper, the k ε turbulence model is used to simulate the three dimensional turbulence flow over the stepped spillway at the Yubeishan reservoir. In order to solve the curved free water surface and to handle the complex boundary conditions, the fractional Volume Of Fluid (VOF) model that is applicable to the solution of the stratified two phase flow is introduced along with k ε turbulence model and the unstructured grid is used for the discretization of the irregular simulation domain. By these methods, the turbulence flow field of the stepped spillway is simulated successfully. The location of the free surface along the spillway, the magnitude and distribution of the velocity, the pressure on the step surface, the turbulence kinetic energy and turbulence dissipation rate are obtained by simulation. The changes and distributions of these characteristics along the width of the spillway are also obtained. The energy dissipation ratio of the stepped spillway is calculated according to the upstream and downstream water depth and velocities

关键词： stepped spillway turbulence numerical simulation turbulence model VOF model

UMVUE OF POLYNOMIALS OF (EX)^(-1) FOR SEVERAL NATURAL EXPONENTIAL FAMILIES ON THE POSITIVE LINE

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Systems Science and Mathematical Sciences 2000年第4期13卷 337-343页

作者： CHEN Hongjian (college of Mathematics, sichuan university, chengdu 610064. China) 四川大学数学学院四川成都 610064

In this paper, we obtain the UMVUE gn(1) of a polynomial of 1/m, say g(1/m), for several NEFs on [0, +∞), where m = E(X) and gn(1) is a polynomial of 1 with the same degree as g(1/m). These estimators are asymptotically normal and asymptotically efficient. The NEFs are the Gamma, the Inverse Gaussian and the Ressel as well as the Abel families.

关键词： UMVUE natural exponential family polynomial of inverse of mean.

GIS-based risk analysis of debris flow:an application in sichuan, southwest China

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International Journal of Sediment Research 2008年第2期23卷 138-148页

作者： B.F.DI1,2,3,N.S.CHEN1,P.CUI1,Z.L.LI1,Y.P.HE4.and Y.C.GAO1 3 1 Ph.D.,chengdu Institute of Mountain Hazards and Environment,CAS,chengdu 61004.,China,Department of Architecture & Environment,sichuan university,chengdu 610065,China,Graduate university of Chinese Academy of Sciences,Beijing 10004.,China,2 Prof.,Department of Architecture & Environment,sichuan university,chengdu 610065,China,3 Graduate university of Chinese Academy of Sciences,Beijing 10004.,China 4.Department of Civil and Environmental Engineering,San Diego State university,5500 Campanile Dr.San Diego,CA 92121,USA [a]Ph.D. chengdu Institute of Mountain Hazards and Environment CAS chengdu 61004. China Department of Architecture & Environment sichuan university chengdu 610065 China Graduate university of Chinese Academy of Sciences Beijing 10004. China [b]Prof. Department of Architecture & Environment sichuan university chengdu 610065 China [c]Graduate university of Chinese Academy of Sciences Beijing 10004. China [d]Department of Civil and Environmental Engineering San Diego State university 5500 Campanile Dr. San Diego CA 92121 USA

Debris flow is a serious geologic hazard in *** is estimated that nationally debris flows cause up to 2 billion RMB(250 million US$) in damages and 300-600 deaths and injuries *** mitigate debris flow hazards,it is necessary to map,model,and identify zones of debris flow hazards and vulnerability as to inform the local people about the potential risk with a geographic information *** research presents a regional scale case study modeling debris flow risk(hazard and vulnerability) in sichuan Province,Southwestern *** this area,3,290 debris flows have been identified and the spatial-temporal distribution and activity characteristics of them have been *** on the available meteorological data,a Digital Elevation Model with the rate of 1:250,000 and a regional geological map,the 24.hr rainfall threshold(y) for debris flow occurrence is closely related(significant at 99% confidence level) to the index(x) defined using a geology factor(rock hardness:a) and a topographical factor(channel gradient:d) where y = 21 + 10200 / x,in which x = 2.7 × ea + 1000 × *** discipline is constructive in developing the rainfall threshold for debris flow activity in remote mountainous areas that lack *** a given watershed,a four-level debris flow hazard map is developed by comparing the rainfall threshold to the design rainfall intensities with 50-,20-,and 5-year average recurrence intervals,*** degree of debris flow vulnerability is determined by the watershed socio-economic conditions.A four-class debris flow risk map,at the final phase of the research,is generated by combining debris flow hazards and *** the debris flow risk assessment,the sichuan Province is classified into the slight,moderate,severe and very severe regions,which accounts for 36%,19%,20% and 25% of total area respectively.

关键词： Debris flow Geographic information system Hazard Vulnerability Risk Rainfall threshold

Engineering Geological Study of Regional Tectonic Stability in the Area of the Longyang Gorge Power Station on the Huanghe (Yellow) River

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Acta Geologica Sinica(English Edition) 1989年第2期63卷 197-209页

作者： Wang Shitian, Li Yusheng, Su Daogang and Wei Lunwu chengdu college of Geology, chengdu, sichuan Fei Zhenbi chengdu college of Geology Chengdu Sichuan

In the stability study of the regional structures in the area of the Longyang Gorge Hydroelectrical Power Station, a model of the current stress-deformation field of the area was constructed based on analyses of available data of regional surveys and historical earthquakes and field investigations of active faults and ancient earthquakes. This model was examined and verified by physical and mathematical simulation experiments, and quantitative relations and data were obtained.

关键词： River area Engineering Geological Study of Regional Tectonic Stability in the Area of the Longyang Gorge Power Station on the Huanghe Yellow

TOEPLITZ OPERATORS AND ALGEBRAS ON DIRICHLET SPACES

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Chinese Annals of Mathematics,Series B 2002年第3期23卷 385-396页

作者： CAO GUANGFU Department of Mathematics, sichuan university, chengdu 610064. China. Department of Mathematics Sichuan University Chengdu 610064 China

The automorphism group of the Toeplitz C^*- algebra, J(C^1), generated by Toeplitz op-erators with C^1-symbols on Dirichlet space D is discussed; the K0, K1-groups and the first cohomology group of J(C^1) are computed. In addition, the author proves that the spectra of Toeplitz operators with C^1-symbols are always connected, and discusses the algebraic prop-erties of Toeplitz *** particular, it is proved that there is no nontrivial selfadjoint Toeplitz operator on D and Tψ^* = Tψ^- if and only if Tψ is a scalar operator.

关键词： Dirichlet space Toeplitz operator Toeplitz algebra