The Best Natural Boundary:a New Concept Developed by Combining the Sequence Boundary with the GSSP

Through a detailed study of sequence boundaries, it is concluded that sequence stratigraphy is an independent regional and transitional stratigraphic system between local lithostratigraphy and global chronostratigraphy. Therefore, a new tripartite stratigraphic classification scheme has been proposed. By combining organically the concept of sequence boundaries with the GSSP, it is suggested that the GSSP should be chosen in a conformale portion of a related sequence boundary, and the boundary established in light of this concept is defined as the Best Natural Boundary (BNB). The definition of the BNB points out the working area and stratigraphic level for the GSSP. By referring to a case study of the Permian Guadalupian/Lopingian boundary, the concept of the BNB has been elaborated in detail, and it is proposed that the BNB of the Guadalupian and the Lopingian lies between the Mesogondolella granti Zone and the Ctarkina postbitteri Zone, which is also the sequence chronostratigraphic boundary between th     

A HORIZONTAL 2-D HYDRAULIC NUMERICAL MODEL AND IT’S APPLICATIONS TO FLOOD FORECAST

1 INTRODUCTION There were many flood disasters in China in recent years. When the water level in a river is very high, weak parts of its dike may be destroyed resulted in the submersion of the protected land and properties. It is of significance for decision-makers to exactly predict the processes of flood propagation during flood control. There are many modes of dike bursting, such as seepage destroying by overflow on top of dike caused by dike body sinking induced by piping and soil fl…     

三维土-结构动力相互作用的一种时域直接分析方法

本文提出了一种分析三维土-结构动力相互作用的时域直接方法。该方法采用集中质量显式有限元和透射人工边界模拟无限域地基,通过编制的FORTRAN程序实现;采用ANSYS软件对上部结构进行建模分析,并通过FORTRAN程序对ANSYS软件的调用,实现了土与结构系统在地震作用下的整体分析。该方法为显隐式相结合的方法,地基和上部结构可采用不同的时间步距进行分析,可大大提高效率。通过两算例,验证了该方法的可行性。     

基于数字地形的三维道路快速建模与应用

介绍一种在高精度三维地形模型的基础上,通过导入道路规划设计快速生成三维道路模型,并进行土石方量计算等量化分析的方法。基于三维道路模型,可以开展各类可视化分析和规划管理工作,为非专业人士理解规划设计意图提供了直观的方式。最后,以典型示范应用为例,说明研究成果可应用的领域和效果。     

上海市水准网复测数据分析与应用

对水准网平差的理论依据、精度评定做了介绍,结合上海市2011年水准网数据,就平差方案、精度评定和成果分析等进行了探讨。通过选取大量的实践数据验证分析,得出了精度较为准确的验证结果,表明采用按照距离定权分等级平差获得的成果可作为此次平差数据处理的最终成果,提出成果的应用方法。     

A high order WENO finite difference scheme for incompressible fluids and magnetohydrodynamics

We present a high order accurate weighted essentially non-oscillatory (WENO) finite difference scheme for solving the equations of incompressible fluid dynamics and magnetohydrodynamics (MHD). This scheme is a direct extension of a WENO scheme that has been successfully applied to compressible fluids, with or without magnetic fields. A fractional time-step method is used to enforce the incompressibility condition. Two basic elements of the WENO scheme, upwinding and wave decomposition, are shown to be important in solving the incompressible systems. Numerical results demonstrate that the scheme performs well for one-dimensional Riemann problems, a two-dimensional double-shear flow problem, and the two-dimensional Orszag–Tang MHD vortex system. They establish that the WENO code is numerical stable even when there are no explicit dissipation terms. It can handle discontinuous data and attain converged results with a high order of accuracy.     

计算断层自发破裂过程的离散网格划分研究

离散化网格的空间步长选取在各种数值算法中都是一个很受关注的问题,在全空间均匀介质模型和简单离散化方案下,利用边界积分方程方法研究在自发破裂求解过程中动力学参数组合Dc和Te (Dc为临界滑动弱化位移,Te为有效的断层破裂面上的初始应力)对计算网格划分的影响,初步得到了Dc和Te参数空间中的有效计算网格的选取规律,对合理、有效地运用边界积分方程方法计算地震震源的破裂过程具有重要的指导意义.      

Inter-Comparison of lO-year Precipitation Simulated by Several RCMs for Asia

In phase Ⅱ of the Regional Climate Model Inter-comparison Project （RMIP） for Asia, the regional climate has been simulated for July 1988 through December 1998 by five regional climate models and one global variable resolution model. Comparison of the 10-year simulated precipitation with the observations was carried out. The results show that most models have the capacity to reproduce the basic spatial pattern of precipitation for Asia, and the main rainbelt can be reproduced by most models, but there are distinctions in the location and the intensity. Most models overestimate the precipitation over most continental regions. Interannual variability of the precipitation can also be basically simulated, while differences exist between various models and the observations. The biases in the stream field are important reasons behind the simulation errors of the Regional Climate Models （RCMs）. The cumulus scheme and land surface process have large influences on the precipitation simulation. Generally, the Grell cumulus scheme produces more precipitation than the Kuo scheme.     

闭合气压系统中心位置指数的计算方案

王盘兴等在＂闭合气压系统环流指数的定义及计算＂一文中定义了闭合气压系统的面积指数S、强度指数P和中心位置指数（λc,φc）,并给出了它们的计算方案。但其中（λc,φc）的计算方案对低纬系统的计算存在明显误差,误差原因是原方案中的极点球面坐标系不适合低纬系统的计算。本文建立了一套原点位于搜索区Ω中心的新球面坐标系,通过坐标转换实现了低纬闭合气压系统中心位置指数（λc,φc）的准确计算。对7月南亚高压和1月蒙古高压中心位置指数（λc,φc）的实际计算表明,它既消除了低纬系统（南亚高压）（λc,φc）原计算方案的明显误差,又保持了与高纬系统（蒙古高压）（λc,φc）原计算方案计算结果的一致。因此,本文给出了适于计算任意纬度闭合气压系统中心位置指数（λc,φc）的计算方案。