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921.
《International Journal of Digital Earth》2013,6(4):315-325
Abstract After the set-up of a spatial data infrastructure (SDI) and a national information infrastructure (NII) in many countries, the provision of geo-services became one of the most important and attractive tasks. With the integration of global positioning system (GPS), geographic information system (GIS) and remote sensing (RS), we can, in principle, answer any geo-spatial related question: when and where what object has which changes? An intelligent geo-service agent could provide end-users with the most necessary information in the shortest time and at the lowest cost. Unfortunately there is still a long way to go to achieve such goals. The central component in such geo-services is the integration of the spatial information system with a computing grid via wire- and wireless communication networks. This paper will mainly discuss the grid technology and its integration with spatial information technology, expounding potential problems and possible resolutions. A novel categorising of information grids in the context of geo-spatial information is proposed: generalised and specialised spatial information grids. 相似文献
922.
准确界定亚暴起始时刻是理解亚暴相关问题的关键.已有研究主要集中在两方面:一是从极光图像中人工挑选亚暴事件进行案例分析或统计分析来研究亚暴发生机制及亚暴期间的地磁环境;二是基于一些空间物理参数,如AE指数、SME(SuperMAG electrojet)指数、Pi2、正弯扰等,采用人眼判断或是模式识别的方法从中找出亚暴起始时刻.本文尝试采用模式识别的方法从紫外极光图像中自动地检测出亚暴膨胀期起始时刻.首先,将紫外极光图像通过网格化处理转换到磁地方时-地磁纬度(MLT-MLAT)直角坐标下,然后通过模糊c均值聚类方法提取亮斑,再考察亮斑强度是否增强、面积是否极向膨胀来判断是不是亚暴事件.本文方法在1996年12月-1997年2月这三个月的Polar卫星紫外极光图像上进行了实验验证.我们将检测到的亚暴起始时刻与Liou(J. Geophys. Res., 2010, 115: A12219)的人工标记进行了对比,并详细分析了与标记不一致的多检和漏检事件.本文提出的自动检测方法可以快速地从海量紫外极光图像中完成亚暴事件的初步筛选,方便研究人员进一步深入研究极光亚暴. 相似文献
923.
《Urban geography》2013,34(2):162-184
Port competition at both the regional and global scales results in port concentration and deconcentration, respectively. Whereas a number of recent studies interpret such phenomena as the effects of global forces such as containerization, few researchers have investigated local forces, such as the evolving relationships between urban policy and port growth. This study compares how two global hub port cities in the Asia-Pacific region, Hong Kong and Singapore, have sustained their port functions while transforming into major economic centers. Entropy indexes are calculated by district based on service industries related to port activities between 1993 and 2004. The results show the influences of port competition, lack of space, and congestion on changes in port-related activities. We conclude that cross-border integration is a main differentiating factor in the evolution of these hub port cities. 相似文献
924.
Assessing Natural and Cultural Determinants of Urban Forest Quality in Nanjing (China) 总被引:1,自引:0,他引:1
《自然地理学》2013,34(5):455-473
This study assessed underlying natural and cultural determinants of tree health and ways to improve urban forest performance in compact Nanjing city. Two groups of factors were investigated: (1) habitat conditions, including planting site, ground-cover, land cover, and district; and (2) tree traits, including species provenance and seasonality, and tree dimensions. A stratified sampling strategy selected 6351 trees for detailed assessment. The data were analyzed by multivariate logistic regressions. Institutional, park-garden and industrial trees with more open-space sites with vegetated ground-cover performed better than roadside and residential ones. Poor trees in confined residential sites deviated from those in other cities. Park-garden sites did not always nurture meritorious, large and diversified trees. District differentiation in tree performance was related to land cover. Exotic and evergreen species grew better than indigenous and deciduous, offering hints on species-habitat matching. Detailed field and statistical analyses could yield tree-environment information to enhance urban forestry research and management. 相似文献
925.
优化开发区域制造业企业迁移的因素及其区域影响——以广东东莞市为例 总被引:5,自引:1,他引:4
优化开发区域是区域发展的较高级阶段,其内部企业迁移的规律比较复杂。选择制造业发达地区——广东东莞市为案例区,采取半结构式访谈法和调查问卷法探讨优化开发区域制造业企业迁移的影响因素及其区域影响。研究表明,现阶段东莞市劳动密集型企业迁出和资本技术密集型企业迁入并存,劳动密集型企业迁出是要素成本、环境管制、区域依赖性和地方政府博弈相互作用的结果,而产业基础、区域创新要素、产业政策和区域软环境等因素促进资本技术密集型企业的迁入;企业迁移可以促进区域产业升级转型,提高区域生产空间质量和优化区域国土空间结构。 相似文献
926.
This study assesses surface urban heat island (SUHI) effects during heat waves in subtropical areas. Two cities in northern Taiwan, Taipei metropolis and its adjacent medium-sized city, Yilan, were selected for this empirical study. Daytime and night time surface temperature and SUHI intensity of both cities in five heat wave cases were obtained from MODIS Land-Surface Temperature (LST) and compared. In order to assess SUHI in finer spatial scale, an innovated three-dimensional Urbanization Index (3DUI) with a 5-m spatial resolution was developed to quantify urbanization from a 3-D perspective using Digital Terrain Models (DTMs). The correlation between 3DUI and surface temperatures were also assessed. The results obtained showed that the highest SUHI intensity in daytime was 10.2 °C in Taipei and 7.5 °C in Yilan. The SUHI intensity was also higher than that in non-heat-wave days (about 5 °C) in Taipei. The difference in SUHI intensity of both cities could be as small as only 1.0 °C, suggesting that SUHI intensity was enhanced in both large and medium-sized cities during heat waves. Moreover, the surface temperatures of rural areas in Taipei and Yilan were elevated in the intense heat wave cases, suggesting that the SUHI may reach a plateau when the heat waves get stronger and last longer. In addition, the correlation coefficient between 3DUI and surface temperature was greater than 0.6. The innovative 3DUI can be employed to assess the spatial variation of temperatures and SUHI intensity in much finer spatial resolutions than measurements obtained from remote sensing and weather stations. In summary, the empirical results demonstrated intensified SUHI in large and medium-sized cities in subtropical areas during heat waves which could result in heat stress risks of residents. The innovative 3DUI can be employed to identify vulnerable areas in fine spatial resolutions for formulation of heat wave adaptation strategies. 相似文献
927.
数字化城市管理简称数字城管,就是指用信息化手段和移动通信技术手段来处理、分析和管理整个城市的所有城管部件和城管事件信息,促进城市管理的现代化的信息化措施。本文以宁波为例通过研究宁波的数字城管的结构组成、管理模式、工作流程、运行绩效,从中发现不足之处并进行分析,最后给出建议。 相似文献
928.
针对全球六边形离散格网的三维显示化方法开展研究,设计了一种六边形格网的空间层次结构(hexagonalquaternary balanced structure,HQBS),采用四位码元对格网单元进行编码,定义并实现了格网向量的基本运算,利用这些运算可以方便地实现格网单元的空间索引。在此基础上还研究了全球离散格网的动态生成与显示算法、可视化区域裁剪等相关内容。试验表明:全球格网动态生成的效率110~370单元/ms之间,加载空间数据后,格网数据和空间数据逐层加载的时间在300 ms左右,能够保证加载空间数据后的显示刷新率在20帧/s左右。 相似文献
929.
930.
在"数字城市地理空间框架"建设项目的要求下,设计并建立了基于Geodatabase模型的城市基础地理信息数据库,并以此为依托,采用C/S架构,通过分析基础地理信息数据库管理的要求与目标,开发实现了基于Ar-cEngine的城市基础地理信息数据库管理系统。 相似文献