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Journal of Hydrodynamics 2010年第3期22卷 419-429页

作者： ZHANG Xi-bing HU De-chao WANG Min state key laboratory of Water Resources and Hydropower engineering Science Wuhan University Wuhan430072 China Yangtze River scientific Research institute Wuhan 430010 China state key laboratory of Hydroscience and engineering Tsinghua University Beijing 100084 China

The main river, the Dongting Lake and river networks in the Jingjiang reach of the Yangtze River constitute a complex water system, for which a full 2-D hydrodynamic model is established instead of the traditional 1-D or compound models for simulation of such complex systems, based on the latest developments of computer technologies and numerical methods. To better handle irregular boundaries and keep the computation cost well in a reasonable limit, unstructured grids of moderate scale are used. In addition, a dynamic boundary tracking method is proposed to simulate variable flow domains at different floods, especially, when the moderate scale gird can not describe flows in narrow river-network channels at low water levels. The t9 semi-implicit method and the Eulerian-Lagrangian Method （ELM） are adopted, which make the model unconditionally stable with respect to the gravity wave speed and Courant number restrictions. Properties and efficiency of the model are discussed, and it is concluded that the new model is robust and efficient enough for the simulation of a big, complex water system. Validation tests show that the simulation results agree well with field data. It takes about 0.96 h to complete the computation of a 76 d flood, which indicates that the model is efficient enough for engineering applications.

关键词： 2-D numerical model river network unstructured grid semi-implicit Eulerian-Lagrangian Method (ELM) boundarytracking

Distribution and origin of biologically available phosphorus in the water of the Meiliang Bay in summer

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Science china Earth sciences 2006年第z1期49卷 146-153页

作者： HUANG Qinghui, WANG Zijian, WANG Donghong, MA Mei & WANG Chunxia state key laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental sciences, chinese academy of sciences, beijing 100085, china key laboratory of Yangtze Aquatic Environment (Ministry of Education), College of Environmental Science and engineering, Tongji University, Shanghai 200092, china state key laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing China key laboratory of Yangtze Aquatic Environment (Ministry of Education) College of Environmental Science and Engineering Tongji University Shanghai China

The investigation and continuous monitoring with an innovative iron oxide embedded cellulose acetate membrane (FeO/CAM) on the concentrations of biologically available phosphorus (BAP) were conducted in the Meiliang Bay of the Taihu Lake during summer in 2004. The results showed that the concentrations of dissolved (FeO-DP), particulate (FeO-PP) and total bioavailable phosphorus (FeO-P) had similar horizontal distribution. The BAP concentrations were the highest in those estuaries in the northern bay. With the decrease of the distance to the estuary or long shore,there was little difference between BAP concentrations in an open lake area. During the observation period, algal blooms occurred in most waters of the northern bay, which was reflected from the high concentrations of chlorophyll a (Chl-a). While they were not highest in the estuarine waters of those major rivers, this is the case for the BAP concentrations. The concentrations of Chl-a had a significantly positive correlation with those of bioavailable phosphorus in the open area of the Meiliang *** the sediment resuspension induced by wind and wave, BAP concentrations increased in a short-term, indicating that the riverine P inputs mainly contribute to the concentrations of BAP in the estuarine water while internal P release was the major source of BAP in the open lake area. In the eutrophic shallow lake, the blooms of alga may cause pH increase and further result in internal P release. The above results showed that the new membrane of FeO/CAM can be used to monitor the concentrations of BAP and provide the scientific justifications for the control strategy of the lake eutrophication.

关键词： phosphorus, bioavailability, eutrophication, resuspension, Taihu Lake.

A FINITE ELEMENT ALGORITHM AND ITS CONVERGENCE ANALYSIS FOR ELLIPTIC PROBLEMS WITH SMALL PERIODIC STRUCTURE

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A FINITE ELEMENT ALGORITHM AND ITS CONVERGENCE ANALYSIS FOR ...

Sediment transport capacity of hyperconcentrated flow

庆祝中国力学学会成立50周年暨中国力学学会学术大会’2007

作者： HE Wenming~(*,2)) CUI Junzhi~(**) *(Department of mathematics,Wenzhou University,Wenzhou,Zhejiang 325035,china) **(state key laboratory of scientific and engineering computing,institute of computational mathematics and Science-engineering computing,academy of mathematics and Systems Science,chinese academy of sciences,beijing 100080,china)

In this paper,we propose a finite element algorithm for elliptic problems with small periodic structure and present its convergence analysis,whose key is to compute the classical boundary corrector of those equations

关键词： multiscale asymptotic expansion finite element algorithm second order elliptic equations with rapidly oscillating coefficients

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Science china(Physics,Mechanics & Astronomy) 2008年第8期51卷 961-975页

作者： SHU AnPing1,2 & FEI XiangJun2 1 School of Environment & key laboratory of Water and Sediment sciences,Ministry of Education,beijing Normal University,beijing 100875,china 2 state key laboratory of Hydroscience and engineering,Tsinghua University,beijing 100084,china School of Environment & key laboratory of Water and Sediment sciences Ministry of Education Beijing Normal University Beijing China state key laboratory of Hydroscience and engineering Tsinghua University Beijing China

As one of the most important components of river mechanics,sediment transport capacity of sediment-laden flows has attracted much attention from many researchers working on river mechanics and hydraulic engineering. Based on the time-averaged equation for a turbulent energy equilibrium in solid and liquid two-phase flow,an expression for the efficiency coefficient of suspended load movement was derived for the two-dimensional,steady,uniform,fully-developed turbulent flow. A new structural expression of sediment transport capacity was achieved. Using 115 runs of flume experimental data,which were obtained through two kinds of sediment transport experiments in the state of equilibrium,in combination with the basic rheological and sediment transporting characteristics of hyperconcentrated flow,the main parameters in the structural expression of sediment transport capacity were calibrated,and a new formula of sediment transport capacity for hyperconcentrated flow was developed. A large amount of field data from the Yellow River,Wuding River,and Yangtze River,etc. were adopted to verify the new formula and good agreement was obtained. These results above contribute to an improved theoretical system of river mechanics and a reliable tool for management of rivers carrying high concentration of sediments.

关键词： hyperconcentrated flow turbulent energy equilibrium efficiency coefficient sediment transport capacity

A SEMI-IMPLICIT 3-D NUMERICAL MODEL USING SIGAM-COORDINATE FOR NON-HYDROSTATIC PRESSURE FREE-SURFACE FLOWS

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Journal of Hydrodynamics 2011年第2期23卷 212-223页

作者： HU De-chao FAN Bei-lin WANG Guang-qian ZHANG Hong-wu state key laboratory of Hydroscience and engineering Tsinghua University Beijing 100084 China Yangtze River scientific Research institute Wuhan 430010 China

A 3-D numerical formulation is proposed on the horizontal Cartesian, vertical sigma-coordinate grid for modeling non-hydrostatic pressure flee-surface flows. The pressure decomposition technique and 0 semi-implicit method are used, with the solution procedure being split into two steps. First, with the implicit parts of non-hydrostatic pressures excluded, the provisional velocity field and free surface are obtained by solving a 2-D Poisson equation. Second, the theory of the differential operator is employed to derive the 3-D Poisson equation for non-hydrostatic pressures, which is solved to obtain the non-hydrostatic pressures and to update the provisional velocity field. When the non-orthogonal sigma-coordinate transformation is introduced, additional terms come into being, resulting in a 15-diagonal, diagonally dominant but unsymmetric linear system in the 3-D Poisson equation for non-hydrostatic pressures. The Biconjugate Gradient Stabilized （BiCGstab） method is used to solve the resulting 3-D unsymmetric linear system instead of the conjugate gradient method, which can only be used for symmetric, positive-definite linear systems. Three test cases are used for validations. The successful simulations of the small-amplitude wave, a supercritical flow over a ramp and a turbulent flow in the open channel indicate that the new model can simulate well non-hydrostatic flows, supercritical flows and turbulent flows.

关键词： 3-D numerical model non-hydrostatic sigma-coordinate semi-implicit pressure-splitting

On the placement of actuators and sensors for flexible structures with closely spaced modes

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Science china(Technological sciences) 2010年第7期53卷 1973-1982页

作者： LIU XiaoXiang1,2 & HU Jun1,2 1 beijing institute of Control engineering, beijing 100190, china 2 state key laboratory of Science and Technology on Space Intelligent Control, beijing 100190, china beijing institute of Control engineering state key laboratory of Science and Technology on Space Intelligent Control

This paper analyzed the fundamental limitations of previous work and developed a new method to optimally locate actuators and sensors for structures with close modes. Optimization criteria were defined based on the distinguishing modal controllability and observability measures of close modes. An appropriate genetic algorism was adopted as the optimization algorism. Solving the high order Lyapunov functions was avoided by means of the closed-form expressions for controllability and observability Grammians. Since structure with widely separated natural frequencies is approximately balanced, computational efficiency was improved by grouping close modes together and dealing with the resulting subsystems independently. Finally, the effectiveness and optimality of the novel placement scheme were verified on a model structure with close modes.

关键词： close modes controllability/observability sensor/actuator optimization criterion optimization algorithm

A Simple Multistart Algorithm for Global Optimization

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运筹学学报 1997年第2期1卷 1-11页

作者： FRED J. HICKERNELL(Department of mathematics, Hong Kong Baptist University, Hong Kong)YAXIANG YUAN(state key laboratory of scientific and engineering computinginstitute of computational mathematics and scientific/engineering computingchinese academy of Sc 香港浸会大学香港中科院计算数学与科学工程计算所科学与工程计算国家重点实验室北京

A generalization of the multistart algorithm is proposed for finding the globalminimizer of a nonlinear function of n variables. Our method concentrates a quasirandomsample by performing a few inexpensive local searches. The sample is thed reduced byreplacing worse points by flew quasirandom points. A complete local search is performedonly on those points with small function values. This method performs favorably incomparison to other global optimization methods.

关键词： nonlinear optimization global minimizer random points quasirandom points

Projected Barzilai-Borwein method for large-scale nonnegative image restoration

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Projected Barzilai-Borwein method for large-scale nonnegativ...

ECSTM study of adsorption of C_(60),C_(70),C_(86) and Y@C_(82) on Au(111)

中国科学院地质与地球物理研究所2007学术年会

作者： YANFEI WANG~(*+)and SHIQIAN MA~(?) + institute of Geology and Geophysics,chinese academy of sciences, P.O.Box 9825,beijing,100029,P.R.china (?) state key laboratory of scientific and engineering computing, institute of computational mathematics and scientific/engineering computing, academy of mathematics and Systems Science,chinese academy of sciences, P.O.Box 2719,beijing,100080,P.R.china

Image restoration refers to minimizing the degradation caused by the sensor environment,such as misfocused CCD cameras,nonuniform motions,atmospheric aerosols,and atmospheric *** image restoration problems,it is reasonable to add nonnegative constraints because of the physical meaning of the ***,the problem can be expressed as a quadratic programming problem with nonnegative ***,in previous research,a parameterization technique is needed to reduce the problem into an unconstrained optimization *** avoid parameterization techniques,we apply the recently developed projected Barzilai-Borwein(PBB) method to solve this quadratic programming ***, a novel approach for reducing the cost of matrix-vector multiplication is proposed when applying BB and PBB methods for atmospheric image *** numerical experiments show that this method is promising for large-scale image restoration problems.

关键词： 65J10 65K10 65F22

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Science china Chemistry 2010年第8期53卷 1705-1710页

作者： SU GuiJin1,JIA ManKe1,GAN LiHua2 & SHI RuiFang1 1state key laboratory of Environmental Chemistry and Ecotoxicology Research Center for Eco-Environmental sciences,chinese academy of sciences,beijing 100085,china 2School of Chemistry and Chemical engineering,Southwest University,Chongqing 400715,china state key laboratory of Environmental Chemistry and Ecotoxicology Research Center for Eco-Environmental sciences Chinese Academy of Sciences Beijing China School of Chemistry and Chemical engineering Southwest University Chongqing China

The adsorption of a variety of fullerenes (C60,C70,C86,Y@C82) on Au(111) electrode surfaces was comprehensively investigated in 0.1 M HClO4 by electrochemical scanning tunneling microscopy (ECSTM).In the ordered C60's adlayer,C60 molecules formed either (2(1/3) × 2 3～(1/3))or "in-phase" *** high resolution STM image shows that the C60 cage is not simply round but shows a bifurcated *** adsorption orientation of C60 on Au(111) is tentatively *** the ordered C70's adlayer,the perpendicular fullerene molecules are the main adsorption mode and form (2 3～(1/3) × 2 3～(1/3)) ***,for C86 and Y@C82,the ordered adlayer could not be obtained on Au(111) under the present *** differences may be due to the different molecular shapes and sizes,and the encapsulated metal atom which affects the lattice matches with the *** adsorption of fullerene molecules on Au(111) from disorder to order could be tuned simply by steering the dimensional sizes or shapes of the fullerenes used.

关键词： C60 C70 C86 Y@C82 ECSTM Au(111)

Structural ensemble dynamics based closure model for wall-bounded turbulent flow

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Acta Mechanica Sinica 2009年第5期25卷 731-736页

作者： Zhen-Su She Ning Hu You Wu state key laboratory for Turbulence and Complex Systems and Dept Mechanical and Aerospace engineering,College of engineering, Peking University,100871 beijing, china state key laboratory for Turbulence and Complex Systems and Dept Mechanical and Aerospace engineering College of Engineering Peking University Beijing China

Wall-bounded turbulent flow involves the development of multi-scale turbulent eddies, as well as a sharply varying boundary layer. Its theoretical descriptions are yet phenomenological. We present here a new framework called structural ensemble dynamics （SED）, which aims at using systematically all relevant statistical properties of turbulent structures for a quantitative description of ensemble means. A new set of closure equations based on the SED approach for a turbulent channel flow is presented. SED order functions are defined, and numerically determined from data of direct numerical simulations （DNS）. computational results show that the new closure model reproduces accurately the solution of the original Navier-Stokes simulation, including the mean velocity profile, the kinetic energy of the streamwise velocity component, and every term in the energy budget equation. It is suggested that the SED-based studies of turbulent structure builds a bridge between the studies of physical mechanisms of turbulence and the development of accurate model equations for engineering predictions.

关键词： Turbulence Closure equation Channel flow Structural ensemble dynamics