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排序方式: 共有102条查询结果,搜索用时 46 毫秒
81.
82.
分析了Pope-Hinsken(P-H)算法的基本原理,将其应用于大角度影像的空间后方交会,给出了误差方程和计算方案,并通过对比实验加以验证。结果表明:1)在空间后方交会中采用单位四元数构造旋转矩阵可显著降低算法的初值敏感性;2)与同类方案相比,该方案具有误差方程更简洁、收敛性更强的特点;3)该方案的解算精度与现有方案一致,稳定可靠。  相似文献   
83.
基于Pope-Hinsken算法的空间后方交会   总被引:1,自引:0,他引:1  
分析了Pope-Hinsken(P-H)算法的基本原理,将其应用于大角度影像的空间后方交会,给出了误差方程和计算方案,并通过对比实验加以验证。结果表明:1)在空间后方交会中采用单位四元数构造旋转矩阵可显著降低算法的初值敏感性;2)与同类方案相比,该方案具有误差方程更简洁、收敛性更强的特点;3)该方案的解算精度与现有方案一致,稳定可靠。  相似文献   
84.
This paper aims to refine earlier research on the geographies of Islamic financial services (IFS) through a study of how cities are being connected through interlocking directorates in Shari’a advisory boards of IFS firms. The relevance of this analysis is discussed against the backdrop of recent critiques of mainstream ‘world cities’ research because of structuralist and universalizing tendencies. By applying a network concept to the relationalities of world cities within financial circuits, we explore the nested city/firm/actor structure behind Shari’a board membership, and reassess the connectivity of cities in the IFS network in terms of the role and spatialities of interlocking Shari’a boards. The results show that Gulf cities, most notably Manama, Dubai and Kuwait City are particularly well-connected, while also mainstay financial centres outside the Middle East, such as London and New York are networked by interlocking board memberships of a global Shari’a elite. The dominant position of Manama is traced back to its role as a standard-setting city for Shari’a-compliant investments, which materializes through the enacted presence of an array of highly interlocked regulatory bodies and mediating elites.  相似文献   
85.
86.
This empirical article combines insights from previous research on the level of knowledge-intensive service in metropolitan areas with the aim to develop an understanding of the spatial structure of the global service economy. We use a stepwise regression model with the Globalization and World Cities research network's measure of globalized service provisioning as the dependent variable and a range of variables focusing on population, infrastructure, urban primacy, and national regulation as independent variables. The discussion of the results focuses on model parameters as well as the meaning of outliers and is used to explore some avenues for future research.  相似文献   
87.
As an important geophysical tool,high density electrical technique infers the underground geological structures by processing and inverting the apparent resistivity data.Currently,the false anomalies have been frequently occurred in the graph of apparent resistivity pseudo-section or inverted geoelectrical section obtained from high-density electrical technique,and are difficult to remove.In this study,the authors explain the mechanism of the false anomalies and put forward the horizontal differential field method to identify the false anomalies.Based on the analysis of modeling results,this method is applied in the surveying data in Xinlei Quarry of Jiuquan,and the results confirm the effectiveness of the horizontal differential field method.  相似文献   
88.
童晓冲  贲进  张永生 《测绘学报》2007,36(4):428-435
首先介绍全球网格系统的应用需求,讨论采用正多面体剖分的基本要素。在此基础上,提出一种新型的便于存储,具有多分辨率层次索引、管理能力的六边形剖分全球网格系统的设计思路、产生步骤和生成算法。分析现有六边形索引机制的缺陷,给出一种新的球面六边形网格层次结构,在该结构的基础上设计网格的层次化编码方式,成功建立网格的编码空间,详细探讨经纬度坐标与网格地址编码的转换问题,给出并实现基于递归层次离散网格坐标系统的互换算法,严格保证计算的准确性和可靠性。该结构能够无缝地表达和处理不同分辨率的全球网格空间数据。  相似文献   
89.
Kjellström, E., Brandefelt, J., Näslund, J.‐O., Smith, B., Strandberg, G., Voelker, A. H. L. & Wohlfarth, B. 2010: Simulated climate conditions in Europe during the Marine Isotope Stage 3 stadial. Boreas, 10.1111/j.1502‐3885.2010.00143.x. ISSN 0300‐9483. State‐of‐the‐art climate models were used to simulate climate conditions in Europe during Greenland Stadial (GS) 12 at 44 ka BP. The models employed for these simulations were: (i) a fully coupled atmosphere–ocean global climate model (AOGCM), and (ii) a regional atmospheric climate model (RCM) to dynamically downscale results from the global model for a more detailed investigation of European climate conditions. The vegetation was simulated off‐line by a dynamic vegetation model forced by the climate from the RCM. The resulting vegetation was then compared with the a priori vegetation used in the first simulation. In a subsequent step, the RCM was rerun to yield a new climate more consistent with the simulated vegetation. Forcing conditions included orbital forcing, land–sea distribution, ice‐sheet configuration, and atmospheric greenhouse gas concentrations representative for 44 ka BP. The results show a cold climate on the global scale, with global annual mean surface temperatures 5 °C colder than the modern climate. This is still significantly warmer than temperatures derived from the same model system for the Last Glacial Maximum (LGM). Regional, northern European climate is much colder than today, but still significantly warmer than during the LGM. Comparisons between the simulated climate and proxy‐based sea‐surface temperature reconstructions show that the results are in broad agreement, albeit with a possible cold bias in parts of the North Atlantic in summer. Given a prescribed restricted Marine Isotope Stage 3 ice‐sheet configuration, with large ice‐free regions in Sweden and Finland, the AOGCM and RCM model simulations produce a cold and dry climate in line with the restricted ice‐sheet configuration during GS 12. The simulated temperature climate, with prescribed ice‐free conditions in south‐central Fennoscandia, is favourable for the development of permafrost, but does not allow local ice‐sheet formation as all snow melts during summer.  相似文献   
90.
基于全球离散网格框架的局部网格划分   总被引:2,自引:0,他引:2  
从全球离散网格系统的应用需求出发,分析全球框架下建立局部网格的重要性,在此基础上提出全球离散网格系统下同构化的局部网格生成的基本思路,详细分析局部网格的复杂球面边界问题,从点与球面三角形的位置关系入手,讨论点与任意球面多边形的相对位置关系,研究基于球面任意多边形的边缘简化算法、判断点与球面任意多边形相互关系的算法、考虑跨面问题的网格区域裁减以及网格数据的层次生成算法.通过实验证明这些方法的效率和准确性.
Abstract:
Firstly, the paper analyzed the essentiality of generating partial grids based on the application and requirement of discrete global grid systems. And then, we brought forward the fundermental thought of generating partial grid which is under the discrete global grid frame, and discussed the detailed edge problems of partial highprecision grid. Started with the ubiety between a point and a spherical triangle, we discussed the ubiety between a point and a spherical random polygon, and then edge simplifying algorithm of spherical random polygon are studied, as well as co-relationship between points and spherical random polygon, grid district clipping based on spanning the developed surface and grid data hierarchical creating algorithm. In the end we prove exactness and efficiency of the algorithm through the experiments.  相似文献   
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