计算最小走时和射线路径的界面网全局方法

用慢度分块均匀正方形模型将介质参数化，仅在正方形单元的边界上设置计算结点，这些结点构成界面网．根据Ｈｕｖｓｅｎｓ和Ｆｅｒｍａｔ原理，由不断扩张、收缩的波前点扫描代替波前面搜索，在波前点附近点的局部最小走时计算中对波前点之间的走时使用双曲线近似，通过比较确定最小走时和相应的次级源位置，记录在以界面网点位置为指针的３个一维数组中．借助这些数组通过向源搜索可计算任意点（包括界面网以外的点）上的全局最小走时和射线路径．这一方法不受介质慢度差异大小限制，占内存少，计算速度较快，适于走时反演和以Ｍａｓｌｏｖ射线理论为基础的波场计算．     

基于变网格聚类的离群数据的研究

随着计算机技术的迅速发展,计算机在过程控制中起着越来越重要的作用,在集散控制系统中,上位机通过PCU(Process ControlUnit)传送来的数据进行分析处理而后对PCU实现参数整定、报警与管理。因此这一领域的数据挖掘方法研究具有十分重要的意义。文章将根据这一领域的特殊情况,提出一种基于变网格的聚类分析算法分析过程数据库中的离群数据,从而实现系统的预测报警功能。     

An equal area conversion model for rasterization of vector polygons

Vector-raster conversion is one of the classic research topics in the field of Geographical Information Systems (GIS). The algorithms commonly used in GIS are devoted to maintaining the vector polygons' shape characteristics, but neglect the gain and loss of a polygon's area, which is another important attribute. This paper proposes an equal-area conversion model based on an area compensation optimization principle. According to the topological relationship among polygons and boundary grids, a neighborhood compensation principle was adopted to assign the attributes of boundary grids and a global optimization algorithm was developed to minimize area distortion in the whole data set. Two experiments were designed and the results indicated that this algorithm not only guaranteed the area error is as small as possible, but also has the advantage as being adaptive to polygon shape and spatial structure.     

Scalar advection schemes for ocean modelling on unstructured triangular grids

Several schemes for scalar advection on unstructured triangular grids are assessed for possible use in ocean modelling applications. Finite element, finite volume and finite volume–element approaches are evaluated. A series of tests, including a numerical order of convergence analysis, idealized rotating cone and cylinder experiments, and transport of a tracer through the Stommel Gyre representation of ocean basin-scale circulation, are carried out. Volume element Eulerian–Lagrangian and third-order Runge-Kutta discontinuous Galerkin schemes are recommended for use in tracer studies. Taylor–Galerkin and second-order Runge–Kutta discontinuous Galerkin are found to be robust and accurate second-order schemes. When positivity is required, a fluctuation redistribution scheme was found to be an easily implemented, accurate, and computationally efficient approach. Responsible editor: Phil Dyke     

The effect of interpolation methods in surface definition: an experimental study

Mappings of the earth surface and their representation in 3D (three‐dimensional) models are commonly used in most recent research. Modeling research, which starts with classical surveying methods, acquires new dimensions matching the modern technologies. 3D models of any object or earth surface can be used in much visual and scientific research. A digital model of the landscape is an important part within creation of geo‐information systems used in the public administration and in the commercial sphere. It is an important tool in applications such as geomorphology, hydrology, geology, cartography, ecology, mining etc. Values of volume in terrains that do not have regular geometric structure can be obtained more accurately by using 3D models of surfaces with respect to developing technology. Basic data of 3D models must indicate 3D coordinates of the surveyed object in the reference frame. Distribution and intensity of points are important factors in modeling earth surfaces. A minimum number of points is desired in defining an object in 3D. Interpolation methods employing different mathematical models are used to obtain 3D models of terrain surfaces. In this study, the effect of interpolation methods in defining a terrain surface is investigated. For this purpose, a uniform surface, hill‐shaped artificial object with a known volume is employed. The 3D surface and volume are calculated by using 12 different interpolation methods. Point distribution, point intensity and accuracy of point measurements are not considered. The same data set was used for all the interpolation methods. The interpolation methods are compared and evaluated based on the results. Copyright © 2007 John Wiley & Sons, Ltd.     

利用二维DLT及光束法平差进行数字摄像机标定

利用共线方程和二维DLT之间的对应关系导出了由二维DLT的8个参数表达的主纵线方程式，讨论了主点初值和求解方法，给出了单张像片摄像机参数分解不惟一性及临界序列的证明，详细推导了利用二维DLT参数分解摄像机外方位元素初值的实用算法，论述了利用光束法平差进行摄像机标定的数学模型，实际图像数据实验取得了很好的结果，验证了本文所提出的摄像机标定算法的可行性。     

河南朱庄金矿区化探规则测网的布设方法

运用导线分层次逐步布设控制点，测距与视距测量相结合布设基测点的方法，解决通视困难的金矿区布设土壤地球化学测量规则测网效率不高，精度低的问题，使用该方法，数据大大减少，便于计算机随机运算，检查，平差，也便于随时发现问题随时纠正，在河南朱庄金矿区1：1万土壤地球化学测量工作中，各项技术指标均符合规范要求，与传统方法相比，节约一半以上工期，返工率低，该方法建立在有先进的测量仪器和先进的计算工具基础上，仪器越先进，方法的优势越明显。     

MM5模式中不同对流参数化方案的比较试验

应用MM5中尺度模式, 在60、20和10 km模式分辨率下, 分别选用4种不同对流参数化方案 (KUO方案、GRELL方案、KAIN-FRITSCH方案和BETTS-MILLER方案, 以下简称KU、GR、KF和BM方案) 对1996年8月3~4日石家庄暴雨过程进行数值模拟试验.模拟结果的对比分析及其与观测的比较表明:主要雨带位置对参数化方案并不是十分敏感, 但随分辨率提高, 雨带分布特征的模拟更接近实况; 当分辨率提高到10 km时, 虚假的降水中心也明显增加; 模拟的暴雨中心强度随分辨率的提高而增强并随参数化方案的不同有所变化, 但均比实况偏弱.分析还发现, MM5模式的GR、KF及BM方案的次网格降水对总降水的贡献率随分辨率的提高而减小, 而KU方案的情况则呈现出不合理的缓慢增加态势.虽然4种方案下模拟的水平环流特征有较好的一致性, 但模拟的云物理特征和垂直运动特征还是存在一定差别的, 这种差别对定点、定量降水和天空状况、地面气温、湿度等要素的准确预报都会产生影响.因此, 在预报和模拟中应考虑预报和研究对象的特点来选择对流参数化方案.     

Partial melting in the Inzie Head gneisses: the role of water and a petrogenetic grid in KFMASH applicable to anatectic pelitic migmatites

A sequence of prograde isograds is recognized within the Dalradian Inzie Head gneisses where pelitic compositions have undergone variable degrees of partial melting via incongruent melting reactions consuming biotite. Three leucosome types are identified. At the lowest grades, granitic leucosomes containing porphyroblasts of cordierite (CRD‐melt) are abundant. At intermediate grades, CRD‐melt mingles with garnetiferous leucosomes (GT‐melt). At the highest grades, CRD‐melt coexists with orthopyroxene‐bearing leucosomes (OPX‐melt), while garnet is conspicuously absent. The prograde metamorphic field gradient is constrained to pressures of 2–3 kbar below the CRD‐melt isograd, and no greater than 4.5 kbar at the highest grade around Inzie Head. A petrogenetic grid, calculated using thermocalc , is presented for the K₂O–FeO–MgO–Al₂O₃–SiO₂–H₂O (KFMASH) system for the phases orthopyroxene, garnet, cordierite, biotite, sillimanite, H₂O and melt with quartz and K‐feldspar in excess. For the implied field gradient, the reaction sequence predicted by the grid is consistent with the successive prograde development of each leucosome type. Compatibility diagrams suggest that, as anatexis proceeded, bulk compositions may have been displaced towards higher MgO content by the removal of (relatively) ferroan granitic leucosome. An isobaric (P = 4 kbar) T–a_H2O diagram shows that premigmatization fluids must have been water‐rich (a_H2O > 0.85) and suggests that, following the formation of small volumes of CRD‐melt, the system became fluid‐absent and melting reactions buffered a_H2O to lower values as temperatures rose. GT‐ and OPX‐melt formed by fluid‐absent melting reactions, but a maximum of 7–11% CRD‐melt fraction can be generated under fluid‐absent conditions, much less than the large volumes observed in the field. There is strong evidence that the CRD‐melt leucosomes could not have been derived by buoyantly aided upwards migration from levels beneath the migmatites. Their formation therefore required a significant influx of H₂O‐rich fluid, but in a quantity insufficient to have exhausted the buffering capacity of the solid assemblage plus melt. Fluid : rock ratios cannot have exceeded 1 : 30. The fluid was channelled through a regionally extensive shear zone network following melt‐induced failure. Such an influx of fluid at such depths has obvious consequences for localized crustal magma production and possibly for cordierite‐bearing granitoids in general.     

非常定自适应网格模式在台风路径数值预报中的应用

本文将作者在前文中介绍的非常定自适应网格模式用于台风路径的数值预报。由于自适应网格在台风中心附近安排了较密的网格，有效地提高了网格的分辨率，使得台风环流的结构在预报48小时以后仍能保持，其预报的路径与实况相比令人鼓舞。