矢量GIS空间方向关系的演算模型   总被引：5，自引：0，他引：5  

邓敏  刘文宝  李俊杰  孙电 《遥感学报》2006,10(6):821-828

空间方向关系是描述空间目标间位置分布的一类基本空间约束，在GIS中是由形式化模型描述的。但现有模型由于简化假设过多，其描述分辨率较低。以点／点空间方向关系的计算量为基础，在综合考虑空间目标的几何构成和分布关系后，提出了定量化演算空间方向关系的一种新模型。利用该模型的结果，根据定量表达与定性描述之间的转换函数，可以得到相应的定性描述结果。理论分析和算例表明，新模型对目标间距离和目标本身的形状等影响方向关系的参数更为敏感，因而比现有模型有更高的描述分辨率。  相似文献   

空间信息的结构、表达及其理解机制     

杜清运 《武汉大学学报(信息科学版)》1998,(4)

在分析传统地理信息系统理论主要缺陷的基础上,将语言学引入地理信息系统,提出了数字环境下空间信息结构与表达的认识模型——空间信息的语言学模型,探讨了空间信息的语言学特征,主要是语言单位、语法及语义机制,并就其对地理信息系统各环节特别是空间信息的智能化数据处理所产生的影响进行了讨论。  相似文献   

Formulation of discontinuous deformation analysis (DDA) — an implicit discrete element model for block systems     

Lanru Jing 《Engineering Geology》1998,49(3-4):371-381

Continuum-based numerical methods have played a leading role in the numerical solution of problems in rock mechanics and engineering geology. However, for fractured rocks, a continuum assumption often leads to difficult parameters to define and over-simplified geometry to be realistic. In such case, discrete representations of fractures and individual blocks must be adopted. In this paper, a newly emerged member in the family of discrete element methods (DEM), the discontinuous deformation analysis (DDA), is presented, including its variational principle, governing equations, solution techniques and contact representation and detection algorithms. Its relative advantages and shortcomings are compared with the explicit distinct element method and the finite element method. An example of the analysis of tunnel stability is provided to demonstrate the capability of this new method.  相似文献   

AMERICAN ROADS,ROADSIDE AMERICA*     

Karl Raitz 《Geographical review》1998,88(3):363-387

ABSTRACT. Federal support for planning and building roads provided an opportunity to create a new kind of place, the American roadside. The roadside grew up beside the public road as a distinct private space, yet the two were linked as road travelers came to depend on the services provided by people who lived at the road's edge. Federal road-improvement legislation brought discipline to the surveying, construction, and configuration of roads. But roadside structures remained largely the creation of local people, who built a vernacular landscape that was undisciplined and in strong contrast to the road's regimentation. The roadside became a new kind of space occupying the unstable zone between the discipline of the road and the informality of the countryside, a spatial contradiction that gave license to a new, free-wheeling, mercantile logic, an improvisational departure from the staid formality of Main Street.  相似文献   

区域地壳稳定性评价专家系统研究   总被引：4，自引：2，他引：4  

殷跃平  胡海涛 《地质论评》1996,42(2):174-186

重大工程选址区域地壳稳定性评价专家系统的开发涉及到众多学科。本文运用结构矩阵法建立了综合且优化的专家知识结构模型，探讨了专家知识定量表述的心理物理学实验方法，为专家知识的获取和定量表示提供了基础。运用专家系统工具Ｍ．１开发了重大工程选址区域地域壳稳定性评价专家系统（ＣＲＵＳＴＡＢ），含６１０条规则，２００个事实，属于中型专家系统。最后，介绍了该系统在广东核电站选址区域地壳稳定性评价结果。  相似文献   

Expert　system　for　earthquake　prediction（ESEP）（2）－Knowledge　representation　and　evidence　combination     

范洪顺  王碧泉 《地震学报(英文版)》1994,(Z1)

Ｅｘｐｅｒｔｓｙｓｔｅｍｆｏｒｅａｒｔｈｑｕａｋｅｐｒｅｄｉｃｔｉｏｎ（ＥＳＥＰ）（２）－ＫｎｏｗｌｅｄｇｅｒｅｐｒｅｓｅｎｔａｔｉｏｎａｎｄｅｖｉｄｅｎｃｅｃｏｍｂｉｎａｔｉｏｎＨｏｎｇ－ＳｈｕｎＦＡＮ（范洪顺）ａｎｄＢｉ－ＱｕａｎＷＡＮＧ（王碧泉...  相似文献   

制图综合的知识表示   总被引：5，自引：1，他引：5  

应申  李霖 《测绘信息与工程》2003,28(6):26-28

从知识表示方面分析了制图综合的理论，介绍了地图综合的知识表示和地图综合专家系统的基本原理和方法．阐述了基于规则和模型的制图综合知识表示和数据组织形式，提出了制图综合专家系统的设计方案。  相似文献   

Dimensionless Graphical Representation of the Exact Elasto-plastic Solution of a Circular Tunnel in a Mohr-Coulomb Material Subject to Uniform Far-field Stresses     

C. Carranza-Torres 《Rock Mechanics and Rock Engineering》2003,36(3):237-253

  相似文献   

数字高程模型地形描述误差的量化模拟--以黄土丘陵沟壑区的实验为例   总被引：4，自引：0，他引：4  

张勇  汤国安  彭釮 《山地学报》2003,21(2):252-256

本研究以陕北黄土高原丘陵沟壑区为试验样区 ,综合运用统计分析及比较分析的原理与方法 ,通过数学模拟、对比分析、误差可视化分析 ,研究不同空间尺度下DEM地形描述误差的数学转换模型。实验结果证明 ,目前适用于欧洲地区的地形描述误差的模拟方程EtD=q·a·(EtD′) b,经过参数的修正 ,在我国黄土高原丘陵沟壑区具有较高的模拟精度。该模型的建立可以实现应用低空间分辨率的DEM数据在栅格水平模拟高空间分辨率DEM所提取的地形描述误差 ,从而 ,在一定精度范围内大大提高Et的计算速度和计算效率。并且 ,对我国其它地貌类型区类似模型的建立 ,都具有重要的参考意义  相似文献   

Defining the subject of speech - Constructions of authorship in post-unification German media discourse     

Kathrin Hörschelmann 《Geoforum》2007,38(3):456-468

This paper analyses how the authority of west German media workers to produce ‘truthful’ representations about unification and eastern Germany after 1989 was discursively constructed. Rather than simply assuming the superiority of western knowledge, I show that the right of western media producers to speak for and about east Germany had to be constructed and defended discursively on a number of registers. Western journalists, in particular, had to demonstrate their credibility towards west and east German audiences, evidence their ability to report objectively and authoritatively, and prove themselves superior in the production of knowledge. Their truth claims had to be negotiated in the midst of a range of competing discourses. The complicated constitution of audiences meant that western journalists had to cast themselves in various different roles to justify their position as ‘knowing subjects’: as explorers, surveyors, observers, commentators, mediators and/or educators. The paper explores, how the divergence between these different positions was reconciled through a number of discursive strategies. I highlight the ambivalences and internal contradictions produced within journalistic discourses as well as through the existence of differentiated audiences.  相似文献