Simulation of Surface Wave with Large Eddy Simulationin in δ-Coordinate System

A three-dimensional numerical model in the δ-coordinate system is developed to study the problem of waves. Turbulence effects are modeled by a subgfid-scale (SGS) model with the concept of large eddy simulation (LES). The δ-coordinate transformation is introduced to map the irregular physical domain of the wavy free surface and uneven bottom onto the regular computational domain of the shape of rectangular prism. The operator splitting method, which splits the solution procedure into the advection, diffusion, and propagation steps, is used to solve the modified Navier-Stokes Equation.The model is used to simulate the propagation of solitary wave and wave passing over a submerged breakwater. Numerical results are compared with available analytical solutions and experimental data in terms of velocity profiles, free surface displacement, and energy conservation. Good agreement is obtained. The method is proved to be of high accuracy and efficiency in simulating surface wave propagation and wave-structure interaction. It is suitable for the large and irregular physical domain, and requiring the non-uniform grid system. The present work provides a foundation for further studies of random waves, wave-structure interaction, wave-discharge interaction, etc.     

三维GIS在"数字长沙"中的应用实例

通过三维GIS在“数字长沙”中的应用进行了探讨,阐述了利用三维GIS为长沙市政府区域建立三维全信息模型的结构、主要功能及应用。     

关于线路中放样方法探讨

本针对中线放样过程中设计单位未提供线路（包括铁路和公路）中线的逐桩坐标,造成计算量和劳动强度大等困难,介绍一种可行的实际操作方法,在此方法基础上编制的放样程序运用于朔黄铁路征地的中线放样,精度满足要求,具有高效、灵活和精度高等特点。     

淮南市防震减灾决策系统的建立

在机制上将一个地市（淮南市）的地震预报与防震决策融为一个动态整体，从而建立起一个实用性强的防震减灾决策系统，使城市各种防震对策的生成了有更科学的基础，成为市政府在防震减灾决策中不可缺少的工具。     

Wave-induced mixing in the Yellow Sea

Vertical wave-induced mixing parameter Bv expressed in wave number spectrum was estimated in the Yellow Sea. The spatial distributions of By averaged over upper 20 m in 4 seasons were analyzed. It is the strongest in winter because of winter monsoon, and the weakest in spring. Since in summer it plays an important role for circulation of upper layers, its vertical structure was also discussed. Two simulations with and without wave-induced mixing in this season were performed to evaluate its effect on temperature distribution. Numerical results indicate that wave-induced mixing could increase the mixed layer thickness greatly.     

Numerical Modelling of Dissolving and Driving Exploitation of Potash Salt in the Qarhan Playa ? A Coupled Model of Reactive Solute Transport and Chemical Equilibrium in a Multi-component Underground Brine System

Firstly, the macroscopic chemical equilibrium state of a series of chemical reactions between intercrystal brine and its media salt layer （salt deposit） in Qarhan Salt Lake was studied by using the Pitzer theory. The concept of macroscopic solubility product and its relation with accumulated ore dissolving ratio were presented, which are used in the numerical model of dissolving and driving exploitation of potassium salt in Qarhan Salt Lake. And secondly, with a model forming idea of transport model for reacting solutes in the multi-component fresh groundwater system in porous media being a reference, a two-dimensional transport model coupled with a series of chemical reactions in a multi-component brine porous system （salt deposits） was developed by using the Pitzer theory. Meanwhile, the model was applied to model potassium/magnesium transport in Qarhan Salt Lake in order to study the transfer law of solid and liquid phases in the dissolving and driving process and to design the optimal injection/abstraction strategy for dissolving and capturing maximum Potassium/ Magnesium in the mining of salt deposits in Qarhan Salt Lake.     

Parallel finite element modeling of earthquake ground response and liquefaction

Parallel computing is a promising approach to alleviate the computational demand in conducting large-scale finite element analyses. This paper presents a numerical modeling approach for earthquake ground response and liquefaction using the parallel nonlinear finite element program, ParCYCLIC, designed for distributed-memory message-passing parallel computer systems. In ParCYCL1C, finite elements are employed within an incremental plasticity, coupled solid-fluid formulation. A constitutive model calibrated by physical tests represents the salient characteristics of sand liquefaction and associated accumulation of shear deformations. Key elements of the computational strategy employed in ParCYCL1C include the development of a parallel sparse direct solver, the deployment of an automatic domain decomposer, and the use of the Multilevel Nested Dissection algorithm for ordering of the finite element nodes. Simulation results of centrifuge test models using ParCYCLIC are presented. Performance results from grid models and geotechnical simulations show that ParCYCLIC is efficiently scalable to a large number of processors.     

Analysis of groundwater recoverable resource by numerical method in Linfen Basin of Shanxi, North China

Calculation of the groundwater recoverable resource is the main part of groundwater resource evaluation. The three-dimensional groundwater flow model in Linfen Basin was established by GMS software. Then the numerical model was calibrated by observed groundwater level from February to December in 2 000. Based on the calibrated model, the groundwater recoverable resource is calculated. The simulation result shows that under the given value of the groundwater recoverable resource, the groundwater level would decrease significantly in the first 1 000 days, while the water level would drop slowly in 1 000 to 2 000 days, and the water level change tend to be stable after 2000 days.     

Spatio-temporal GIS data model based on event semantics

There are mainly four kinds of models to record and deal with historical information. By taking them as reference, the spatio-temporal model based on event semantics is pro-posed. In this model, according to the way for describing an event, all the in-formation are divided into five do-mains. This paper describes the model by using the land parcel change in the cadastral information system, and ex-pounds the model by using five tables corresponding to the five domains.With the aid of this model, seven ex-amples are given on historical query,trace back and recurrence. This model can be implemented either in the ex-tended relational database or in the ob-ject-oriented database.     

我国1′×1′高程异常模型的建立及应用

高精度地确定我国陆海任意点的似大地水准面高（或称高程异常），其基础是先建立相应区域的高精度、高分辨率的高程异常数字模型，然后在此基础上通过内插软件确定.本文阐述了建立我国陆海1′×1′高程异常数字模型的数据、方法和步骤等.分别采用全国854个（一、二级网和A、B级网点）和75个（地震监测站点）高精度GPS/水准点作为外部检核点，对该数字模型进行了精度估计，结果表明：由该数字模型确定全国任意点高程异常的精度，东部地区分别为±0.18 m和±0.13 m，西部地区分别为±0.30 m和±0.22 m，全国总体精度分别为±0.23 m和±0.17 m.比规划的±0.5 m精度指标提高了1倍多.少部分区域达到了厘米级精度.由1′×1′高程异常数字模型及相应软件确定任意点结果的速度一般在2s内.