等角投影理论和方法综述

等角投影与其它性质投影比较之，其研究尤为深刻，应用也最为广泛。本文对等角投影的历史发展作了简单回顾，重点对等角投影的数学基础、等角投影的一般公式、等角投影变形量度、具有极值特性的等角投影和探求等角投影的方法进行了综述。最后提出需要继续研究的若干问题作为等角投影研究展望。     

无锡市鼋头渚景区岩质边坡崩塌形成机制及防治对策研究

崩塌地质灾害是苏南低山丘陵地区岩质边坡的主要工程地质问题之一。在对无锡鼋头渚景区沿湖景观路崩塌危岩体开展应急调查与测绘的基础上,文章对崩塌危岩体地质背景条件和灾害特征进行了描述,并采用赤平投影法对危岩体结构面组合特征进行了分析;在深入研究崩塌灾害形成原因与破坏模式后,提出采用危岩清除+钢筋混凝土肋柱锚固+挂网喷射混凝土护面+系统截排水+纳入群测群防应急体系的综合防治对策,为苏南丘陵地区同类型软硬互层岩质边坡崩塌灾害防治提供一定的科学依据和参考。     

城市洪涝易损性分类与诊断研究

城市洪涝易损性分析对城市防洪安全具有极其重要的作用。将基于加速遗传算法的投影寻踪模型应用于城市洪涝易损性分类与诊断。运用建议模型探讨了湖南省29个城市的洪涝易损性,将全省洪涝易损性程度划分为5个等级:低度易损性、较低度易损性、中度易损性、较高度易损性、高度易损性,同时与模糊评价结果进行了对比。研究表明,投影寻踪模型客观考虑了各个影响因子的权重,结果合理、可靠,可以在实际的类似问题中应用。     

RDINFO中开放式空问参照系统的设计与实现

介绍了基础地理信息平台软件RDINFO的开放式空间参照系统的设计思想 ,分析了其总体结构 ,提出了其实现方法     

Fracture step structure: geometrical characterization and effects on fluid flow and breakthrough curve

Groundwater flow and solute transport through fractured rock is highly responsive to the hydraulic anisotropy and heterogeneity that are specific to every major fracture. A major fracture is modeled as the combination of some primal master fractures and several splay fractures that branch out from primal master fractures: step structures (or jog parts). Step structures are commonly observed along a major fracture on various scales. Master fractures were formed and developed by shear movement while some splay fractures were formed by extension normal to their wall. This difference in fracturing process may lead to a permeability difference between master fractures and splay fractures which seems to be one of the major factors controlling flow and solute transport through the fracture networks due to its hydraulic anisotropic and heterogeneous features. This study is composed of two major components: (1) identification and characterization of a step structure from borehole data; (2) evaluation of effect of some idealized step structures on breakthrough curve by numerical simulations. The fracture data of four 1000-m boreholes were used to make clear fracture patterns in the Tono area of Japan. Some major fractures were identified using stereographic projection technique. On the basis of these results, several idealized models of a major fracture having a step was constructed for the numerical study. The obtained results from numerical simulations clearly imply that geometry of step structure plays an important role in flow and transport through the fracture networks.     

The application of commutative algebra to geodesy: two examples

Algebra, in particular commutative algebra, is applied here to provide a general unified solution to nonlinear systems of equations encountered in geodesy. Starting with the “Abelian group”, the “polynomial ring” is defined and used to form generators of ideals. By applying Buchberger or polynomial resultant algorithms, these generators are reduced to simple structures often comprising a univariate polynomial in one of the unknowns. The advantage of the proposed unified approach is that it provides exact solutions to geodetic nonlinear systems of equations without the traditional requirements of linearization, iterations or approximate starting values. The commutative algebraic approach therefore alleviates the need for isolated exact solutions to various geodetic nonlinear systems of equations. The procedure is applied to GPS meteorology to compute refraction angles, and Helmert’s one-to-one mapping of topographical points onto the reference ellipsoid.     

契比雪夫投影的研究

根据等角投影理论,推导出了契比雪夫投影公式的具体形式,并对契比雪夫投影在制作中国全图的应用和变形与等角方位投影、等角圆锥投影进行了比较分析.结果表明,契比雪夫投影要优于等角方位投影和等角圆锥投影.     

Groups of Parts and Their Balances in Compositional Data Analysis

Amalgamation of parts of a composition has been extensively used as a technique of analysis to achieve reduced dimension, as was discussed during the CoDaWork'03 meeting (Girona, Spain, 2003). It was shown to be a non-linear operation in the simplex that does not preserve distances under perturbation. The discussion motivated the introduction in the present paper of concepts such as group of parts, balance between groups, and sequential binary partition, which are intended to provide tools of compositional data analysis for dimension reduction. Key concepts underlying this development are the established tools of subcomposition, coordinates in an orthogonal basis of the simplex, balancing element and, in general, the Aitchison geometry in the simplex. Main new results are: a method to analyze grouped parts of a compositional vector through the adequate coordinates in an ad hoc orthonormal basis; and the study of balances of groups of parts (inter-group analysis) as an orthogonal projection similar to that used in standard subcompositional analysis (intra-group analysis). A simulated example compares results when testing equal centers of two populations using amalgamated parts and balances; it shows that, in certain circumstances, results from both analysis can disagree.     

苏丹默鲁特盆地石油开发项目数字地形测量技术分析

以苏丹默鲁特盆地石油开发项目的地形测量工程为例,分析国外的石油开发项目地形测量工作涉及的各个方面。文章从测量工程的坐标和投影系统选择、适用作业规范、控制设计和标石埋设、地形图分幅、图面表示、成果质量控制等多方面阐述分析了其特殊性,并总结了一些经验,以期为以后的此类工程提供借鉴意义。