Some Recurrence Relations Between Hansen Coefficients     

Akmal A. Vakhidov 《Celestial Mechanics and Dynamical Astronomy》2001,81(3):177-190

A new system of recurrence relations for Hansen coefficients is obtained. This system gives a connection between only those coefficients which are included in the disturbing function of planetary or satellite motion and allows to compute efficiently the Hansen coefficients for perturbations both from internal and external bodies. The recurrence process can be realized both from high to low and from low to high harmonical terms of the disturbing function. The corresponding algorithms of evaluation of Hansen coefficients are presented. The efficiency of the obtained system of recurrence relations is discussed.  相似文献   

一种基于梯形剖分的多边形布尔运算方法     

崔璨  王结臣 《测绘学报》2011,40(1):104-110

借鉴计算几何学的理论方法,提出一种基于多边形梯形剖分思想的实现方法.首先利用扫描线技术将多边形分解为梯形面片集,以便将多边形的布尔运算转化为梯形面片间的布尔运算;这些梯形面片以扫描行为单元进行组织,梯形之间的布尔运算被限定在相同的扫描行内,可有效简化核心计算过程;在完成梯形单元布尔运算并得到结果梯形集后,通过边界追踪完...  相似文献   

基于LOG改进算子的边缘检测与面状特征提取     

张盈  张景雄 《测绘信息与工程》2011,(5):8-10

介绍了基于LOG改进算子的边缘检测方法,通过边界跟踪和边界代数,实现了面状特征的快速提取,试验表明,所使用的方法优于区域生长、多尺度分割等传统方法,具有较好地应用前景。  相似文献   

等面积纬度函数和等量纬度变换的直接解算公式   总被引：2，自引：0，他引：2  

李厚朴  边少锋  陈良友 《武汉大学学报(信息科学版)》2011,(7):843-846

为实现等面积投影和等角投影间的直接变换,借助计算机代数系统Mathematica,推导出了等面积纬度函数和等量纬度变换的直接解算公式,并将式中系数统一表示为椭球第一偏心率的幂级数形式,可解决不同参考椭球下的变换问题。算例分析表明,本导出公式的计算误差分别小于10 m2和10-4(″),可供实际使用。  相似文献   

关于有限群超可解性的一种新判定方法     

刘阿明  李保军  黄程 《成都信息工程学院学报》2014,(6):665-668

利用子群的弱s-置换性质研究超可解子群的积的问题,并给出群的超可解性的一些判别方法。设群G可以表示为2个子群A和B的积,A在G中拟正规且B为超可解,如果A的Sylow子群的所有极大子群在G中弱s-置换,则G为超可解群。从而得到1个群为超可解群的这样的一种新判别法。  相似文献   

基于MapReduce的地图代数并行计算方法     

蒋波涛  王艳东 《测绘信息与工程》2014,(3):51-55

针对大规模栅格数据的空间分析,设计并实现了一种基于MapReduce架构的通用地图代数并行计算方法。该方法能将栅格像素矩阵按数据行分割为多个独立的子矩阵,并在并行节点上使用地图代数的四种算子对来自不同矩阵的像素进行分析计算。栅格数据叠加实验结果表明,该方法具备有效性和可靠性,能降低计算对硬件设备的要求,并提升了计算效率。  相似文献   

Cartographic support for locational problem‐solving by groups     

M. P. Armstrong  P. J. Densham 《International journal of geographical information science》2013,27(7):721-749

Collaborative spatial decision‐making environments in which group members individually and collectively pursue solutions to semi‐structured problems have a unique set of geographic visualization requirements. Group members often pursue diverse strategies as they attempt to solve such problems. As a consequence, numerous mapped representations of alternative solutions are generated. It is difficult to compare and synthesize these results, especially when decision‐makers have little or no previous cartographic training. In this paper, we derive several map types that synthesize representations of alternative solutions to location‐selection problems. These synthetic maps, designed to be accessible to group members, are created by decomposing solutions into a collection of atomic elements that are then placed into an accounting framework. Network map algebra operations are performed within this framework, and the results are accumulated and displayed as maps. Group members can use these maps to identify similar and dissimilar elements of alternative solutions to a problem. Such maps are intended to promote discussion and support group consensus‐building activities.  相似文献   

多维统一GIS构建与实现的几何代数方法     

袁林旺  俞肇元  罗文  易琳  闾国年 《地理研究》2013,32(5):974-983

针对时空GIS发展所面临的时空表达不统一,高维扩展困难等问题,基于以多维统一和坐标无关为特征的几何代数理论,建立多维统一GIS构建的层次体系与方法。利用几何代数对象构造中几何维度与Grassmann维度的一致性,实现整合维度结构与几何关系的多维地理对象自适应表达。利用几何代数算子的特征内蕴与结构明晰特性,构建多维统一计算模型以及可支撑复杂地理计算的多维统一分析框架,进而建立基于几何代数的多维统一GIS系统架构与实现方案。对上述关键技术加以实现并进行了相关应用案例分析。结果显示,基于几何代数构建的多维统一GIS有望突破现有时空GIS的不足,可为以多维统一表达与运算为特征GIS的发展提供新的数学工具与实现途径。  相似文献   

Efficiently implementable algebra for distributed in-network spatial analysis     

Farhana Jabeen  Alvaro A.A. Fernandes 《International journal of geographical information science》2013,27(4):815-844

Existing sensor network query processors (SNQPs) have demonstrated that in-network processing is an effective and efficient means of interacting with wireless sensor networks (WSNs) for data collection tasks. Inspired by these findings, this article investigates the question as to whether spatial analysis over WSNs can be built upon established distributed query processing techniques, but, here, emphasis is on the spatial aspects of sensed data, which are not adequately addressed in the existing SNQPs. By spatial analysis, we mean the ability to detect topological relationships between spatially referenced entities (e.g. whether mist intersects a vineyard or is disjoint from it) and to derive representations grounded on such relationships (e.g. the geometrical extent of that part of a vineyard that is covered by mist). To support the efficient representation, querying and manipulation of spatial data, we use an algebraic approach. We revisit a previously proposed centralized spatial algebra comprising a set of spatial data types and a comprehensive collection of operations. We have redefined and re-conceptualized the algebra for distributed evaluation and shown that it can be efficiently implemented for in-network execution. This article provides rigorous, formal definitions of the spatial data types, points, lines and regions, together with spatial-valued and topological operations over them. The article shows how the algebra can be used to characterize complex and expressive topological relationships between spatial entities and spatial phenomena that, due to their dynamic, evolving nature, cannot be represented a priori.  相似文献   

基于波前重建和李代数积分的地震波走时计算   总被引：1，自引：0，他引：1  

张廉萍  刘洪 《吉林大学学报(地球科学版)》2010,40(6):1463-1470

地震波走时计算在数值模拟、层析反演和偏移成像中均有重要意义。将波前重建与李代数积分相结合,提出了一种新的适应横向变速介质的非对称走时算法,称之为wave-front construction-Lie algebra integral(WFC-LAI)算法。本算法利用一次波前重建计算成像射线走时进行坐标变换,将深度域单平方根算子透镜项转化为常数,在射线坐标系下计算李代数积分和指数映射,得到地震波走时的解析表达式。数值试验表明,该方法计算结果与线性横向变速介质中走时的理论值吻合。通过与波前重建结果对比,WFC-LAI算法对于求取横向变速介质中地震波走时是可行的,节省了存储空间,易于并行,有利于提高Kirchhoff积分叠前深度偏移的精度和效率。  相似文献