A global shallow water model using high order multi-moment constrained finite volume method and icosahedral grid

A novel accurate numerical model for shallow water equations on sphere have been developed by implementing the high order multi-moment constrained finite volume (MCV) method on the icosahedral geodesic grid. High order reconstructions are conducted cell-wisely by making use of the point values as the unknowns distributed within each triangular cell element. The time evolution equations to update the unknowns are derived from a set of constrained conditions for two types of moments, i.e. the point values on the cell boundary edges and the cell-integrated average. The numerical conservation is rigorously guaranteed. in the present model, all unknowns or computational variables are point values and no numerical quadrature is involved, which particularly benefits the computational accuracy and efficiency in handling the spherical geometry, such as coordinate transformation and curved surface. Numerical formulations of third and fourth order accuracy are presented in detail. The proposed numerical model has been validated by widely used benchmark tests and competitive results are obtained. The present numerical framework provides a promising and practical base for further development of atmospheric and oceanic general circulation models. (C) 2009 Elsevier Inc. All rights reserved.

Measurement of neutron-removal cross section of neutron-rich nucleus He-8 by using the transmission method

The neutron-rich nucleus He-8 is selected by RIBLL from the breakup of 50MeV/u C-13 on be target at HIRFL. The 2n-removal and 4n-removal cross section of He-8 was measured by using the transmission method. The point that He-4 is He-8 core can be reduced from the experiment data via the Ogawa's theory.

The experimental research for production of hydrogen from n-octane through partially oxidizing and steam reforming method

The reaction of producing hydrogen for fuel cell which used normal octane as gasoline or diesel oil reactant through catalytic partial oxidizing and steam reforming method has been researched in the fixed-bed reactor. A series of catalysts that mainly used nickel supported on Al2O3 have been studied. It showed that the activity of the catalyst was increased with the content of nickel by using only nickel supported on Al2O3. However, its activity was not obviously increased when the content of nickel was over 5 wt%. The conversion ratio of normal octane and hydrogen selectivity were higher at higher reaction temperature. The single noble catalyst of palladium had better stability compared with that of platinum catalyst although their activity and selectivity were similar during the experimental reaction temperature. The prepared bimetallic catalyst consisted mainly of nickel and little noble metal of palladium supported on Al2O3. It showed that this catalyst had higher activity and selectivity, especially at lower or higher reaction temperatures compared with single nickel or palladium catalyst, and better stability. ((C) 2001 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.

Comparison of salt titration and potentiometric titration methods for the determination of zero point of charge

the salt ritration metod was evaluated as a method to determine zpc in comparison with the potentiometric titration method for 26 soil with variable charge clays,i.e.,Oxisols and Ultisols from Thailand and Andisols from Japan. In addition to the determination of ST-pH0 as the zero point of charge, a calculation procedure was adopted here in order to acquire more information from the titration curve . fuithermore, for the purpose of cross-checking of zpc determined by the pt method, the st procedure was successively applied to the samples analyzed by the pt method.

DECODE: a new method for discovering clusters of different densities in spatial data

National Key Basic Research and Development Program of China [2006CB701305]; State Key Laboratory of Resource and Environment Information System [088RA400SA]; Chinese Academy of Sciences

Study of self-assembly of symmetric coil-rod-coil ABA-type triblock copolymers by self-consistent field lattice method

The self-assembly of symmetric coil-rod-coil ABA-type triblock copolymer melts is studied by applying self-consistent field lattice techniques in a three-dimensional space. The self-assembled ordered structures differ significantly with the variation of the volume fraction of the rod component, which include lamellar, wave lamellar, gyroid, perforated lamellar, cylindrical, and spherical-like phases. To understand the physical essence of these phases and the regimes of occurrence, we construct the phase diagram, which matches qualitatively with the existing experimental results. Compared with the coil-rod AB diblock copolymer, our results revealed that the interfacial grafting density of the separating rod and coil segments shows important influence on the self-assembly behaviors of symmetric coil-rod-coil ABA triblock copolymer melts. We found that the order-disorder transition point changes from f(rod)=0.5 for AB diblock copolymers to f(rod)=0.6 for ABA triblock copolymers. Our results also show that the spherical-like and cylindrical phases occupy most of the region in the phase diagram, and the lamellar phase is found stable only at the high volume fraction of the rod.

Joint statistical distribution of two-point sea surface elevations in finite water depth

Based on the second-order random wave solutions of water wave equations in finite water depth, a joint statistical distribution of two-point sea surface elevations is derived by using the characteristic function expansion method. It is found that the joint distribution depends on five parameters. These five parameters can all be determined by the water depth, the relative position of two points and the wave-number spectrum of ocean waves. As an illustrative example, for fully developed wind-generated sea, the parameters that appeared in the joint distribution are calculated for various wind speeds, water depths and relative positions of two points by using the Donelan and Pierson spectrum and the nonlinear effects of sea waves on the joint distribution are studied. (C) 2003 Elsevier B.V. All rights reserved.

A QUASI-SIMPLEX METHOD FOR STRICTLY CONVEX QUADRATIC PROGRAMMING

本文提出一个不用 Kuhn- Tucker条件而直接搜索严格凸二次规划最优目标点的鲁棒方法 .在搜索过程中 ,目标点沿约束多面体边界上的一条折线移动 .这种移动目标点的思想可以被认为是线性规划单纯形法的自然推广 ,在单纯形法中 ,目标点从一个顶点移到另一个顶点。

构造复杂区变速成图方法研究

In the complex structure areas, velocity field building and structure mapping are important for seismic exploration. With the development of seismic exploration, the methods of structure mapping, reservoir prediction and reservoir description all require high precious velocity field. And more accurate depth-structure maps are required for well site design. Aiming at the problems and defects in velocity analysis and structure mapping in oil seismic exploration, the paper which is based on the studies of real data in several areas combines the theories with practical application, and analyzes the precision and applicability of several methods of velocity model building. After that, the following methods are mainly studied: the coherence inversion methods based on the pre-stack CMP gathers or stacking velocity; the interval velocity inversion methods constrained by multi-well; the Random Simulation method; 3D Image Ray Map Migration method and the structure mapping in floating datum and in fixed datum, and then we conclude the method of building high precious seismic velocity field and structure mapping with variable velocity. Firstly, the paper analyses the distributing rule of the velocity variation in the areas with complex structures in the northwest of China, then points out that velocity is a crucial factor which influences the precision of structure mapping, and the velocity variations have something to do with the shapes of the structures, the variety of lithology and so on. The key point of improving the precision of seismic velocity field is to obtain a structure mapping with high precision. We also describe the range and conditions of these methods. Secondly, by comparing many popular methods of velocity model building, we propose a new method in the use of velocity model building. The new method is more effective in velocity model building under every kind of complex condition and is worthy of spreading. At last, the paper fingers out that it is a system engineering to study variable velocity mapping in every kind of complex structure areas. Every step of the work can affect the final results. So it is important to build high efficient and practical velocity model and the flows of mapping processing. The paper builds the flows and gives some examples. The method has been applied in more than ten exploring surveys. The application proves that this method could bring good effect on researching on low-amplitude trap, reservoir prediction, reservoir description and the integrated research of oil&gas geology. Keywords: structure mapping velocity model building complex structure variable velocity media

基于窗口精细结构描述的岩体质量评价及力学参数综合优选

This thesis bases on horizontal research project “The research about the fine structure and mechanical parameters of abutment jointed rock mass of high arch dam on Jinping Ⅰ Hydropower Station, Yalong River” and “The research about the fine structure and mechanical parameters of the columnar basalt rock mass on Baihetan Hydropower Station, Jinsha River”. A rounded system about the fine structure description and rock mass classification is established. This research mainly contains six aspects as follow: (1) Methods about fine structure description of the window rock mass; (2) The window rock mass classification about the fine structure; (3) Model test study of intermittent joints; (4) Window rock mass strength theory; (5) Numerical experimentations about window rock mass; (6) The multi-source fusion of mechanical parameters based on Bayes principle. Variation of intact rock strength and joint conditions with the weathering and relaxation degree is studied through the description of window rock mass. And four principal parameters: intact rock point load strength, integration degree of window rock mass, joint conditions, and groundwater condition is selected to assess the window rock mass. Window rock mass is classified into three types using the results of window rock mass fine structure description combined with joints develop model. Scores about intact rock strength, integrality condition, divisional plane condition and groundwater conditions are given based on window rock mass fine structure description. Then quality evaluation about two different types of rock mass: general joint structure and columnar jointing structure are carried out to use this window rock mass classification system. Application results show that the window rock mass classification system is effective and applicable. Aimed at structural features of window structure of “the rock mass damaged by recessive fracture”, model tests and numerical models are designed about intermittent joints. By conducting model tests we get shear strength under different normal stress in integrated samples, through samples and intermittent joints samples. Also, the changing trends of shear strength in various connectivity rates are analyzed. We numerically simulate the entire process of direct shear tests by using PFC2D. In order to tally the stress-strain curve of numerical simulation with experimental tests about both integrated samples and through samples, we adjust mechanical factors between particles. Through adopting the same particle geometric parameter, the numerical sample of intermittent joints in different connective condition is re-built. At the same time, we endow the rock bridges and joints in testing samples with the fixed particle contacting parameters, and conduct a series of direct shear tests. Then the destructive process and mechanical parameters in both micro-prospective and macro-prospective are obtained. By synthesizing the results of numerical and sample tests and analyzing the evolutionary changes of stress and strain on intermittent joints plane, we conclude that the centralization of compressive stress on rock bridges increase the shear strength of it. We discuss the destructive mechanics of intermittent joints rock under direct shear condition, meanwhile, divide the whole shear process into five phases, which are elasticity phase, fracture initiation phase, peak value phase, after-peak phase and residual phase. In development of strength theory, the shear strength mechanisms of joint and rock bridge are analyzed respectively. In order to apply the deducted formulation conveniently in the real projects, a relationship between these formulations and Mohr-Coulomb hypothesis is built up. Some sets of numerical simulation methods, i.e. the distinct element method (UDEC) based on in-situ geology mapping are developed and introduced. The working methods about determining mechanical parameters of intact rock and joints in numerical model are studied. The operation process and analysis results are demonstrated detailed from the research on parameters of rock mass based on numerical test in the Jinping Ⅰ Hydropower Station and Baihetan Hydropower Station. By comparison，the advantages and disadvantages are discussed. Results about numerical simulation study show that we can get the shear strength mechanical parameters by changing the load conditions. The multi-source rock mass mechanical parameters can be fused by the Bayes theory, which are test value, empirical value and theoretical value. Then the value range and its confidence probability of different rock mass grade are induced and these data supports the reliability design.