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231.
Introduction Sichuan-Yunnan region, located in the east margin of Qinghai-Xizang (Tibetean) Plateau, is a transitional zone between the rapidly upheaving Tibetean Plateau and relatively steady Yangtze Platform. Under the pressure exerted by the northward movement of Indian Plate, Sichuan-Yunnan region has been undergone strong deformation and regmagenesis, becoming one of the regions with the most intensive seismicity in the world. The research on the tectonics and seismicity there is alw… 相似文献
232.
Delayed Geochemical Hazard (DGH briefly) presents the whole process of a kind of serious ecological and environmental hazard caused by sudden reactivation and sharp release of long-term accumulated pollutant from stable species to active ones in soil or sediment system due to the change of physical-chemical conditions (such as temperature, pH, Eh, moisture, the concentrations of organic matters, etc.) or the decrease of environment capacity. The characteristics of DGH are discussed. The process of a typical DGH can be expressed as a nonlinear polynomial. The points where the derivative functions of the first and second orders of the polynomial reach zero, minimum and maximum are keys for risk assessment and harzard pridication.The process and mechanism of the hazard is due to the transform of pollutant among different species principally. The concepts of "total releasable content of pollutant", TRCP, and "total concentration of active specie", TCAS, are necessarily defined to describe the mechanism of DGH. The possibility of the temporal and spatial propagation is discussed. Case study shows that there exists a transform mechanism of "gradual release" and "chain reaction" among the species of the exchangeable and the bounds to carbonate, iron and manganese oxides and organic matter, thus causing the delayed geochemical hazard. 相似文献
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234.
In this paper, we discuss the development of electronic atlas in China, with focus on the issues of visualization. We particularly categorise this development into four periods, and then analyse the characters in each period and discuss the visualization issues. The four periods are highlighted: 1) Infant period (<1990) characterized as computer assisted mapping with products of screen maps; 2) Starting period (1991-1995) characterized as object-oriented mapping with products of interactive maps/atlases; 3) Advancing period (1996-2000) characterized as integrated mapping with products of multimedia cartographic maps; 4) New era (> 2001) characterized as web mapping and adaptive map design with products of Internet maps and atlas as well as adaptive maps. It is obvious that the development follows the logical way from static to dynamic, and even real time visualization, from single user to multiple users, from presentation to exploration for effective communication and knowledge construction. Current research and development projects are focused on customisation of atlas information systems for real-time tasks, Internet operability, small displays and mobile environments. The major challenges involved in each of such customisation processes are identified and commented in relation to the further development of visualization. 相似文献
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237.
Correcting the Smoothing Effect of Ordinary Kriging Estimates 总被引:2,自引:0,他引:2
Jorge Kazuo Yamamoto 《Mathematical Geology》2005,37(1):69-94
The smoothing effect of ordinary kriging is a well-known dangerous effect associated with this estimation technique. Consequently kriging estimates do not reproduce both histogram and semivariogram model of sample data. A four-step procedure for correcting the smoothing effect of ordinary kriging estimates is shown to be efficient for the reproduction of histogram and semivariogram without loss of local accuracy. Furthermore, this procedure provides a unique map sharing both local and global accuracies. Ordinary kriging with a proper correction for smoothing effect can be revitalized as a reliable estimation method that allows a better use of the available information. 相似文献
238.
This paper briefly reviews the sociological literature on the “New” Chinatown phenomenon stressing its structural location
vis-à-vis the “Old” Chinatown and the homeland. It defines the New Chinatown as a panethnopolis, that is a global neighborhood
with a majority population of Chinese immigrants and of other ethnic groups of mostly Asian descent. It analyzes more particularly
the formation, development, and integration of San Francisco’s Richmond District’s New Chinatown into both the city where
it is located and the network of transglobal sites to which it belongs. It provides an interpretation of the New Chinatown
as a cultural enclave within the context of globalization theory. 相似文献
239.
沙漠沙丘污水处理系统:原理、方法和效果 总被引:1,自引:0,他引:1
“沙漠沙丘系统(DDS)”是以地球化学工程学原理为指导的特殊水处理系统,它利用沙漠沙作为滤料,通过“机械过滤”、“化学作用”和“生物作用”净化污染水,一方面可使沙丘变得湿润而不再移动,以固定移动沙漠;另一方面又能净化污染水,最终起到“以害克害、固沙治水、一举多得”的良好综合生态环境效应。DDS是绿色的水处理系统,所需的原料和生成物都属于自然界存在的物质,无二次污染的发生。在DDS设计中,要注意的主要因素应包括:滤料的种类、湿干时间比、微生物培养方式、滤料层厚度、进水水质、时间、温度和pH等。DDS可以把官厅水库水由V类和超V类处理成2~3类水,从而恢复官厅水库的饮用水功能。 相似文献
240.