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131.
云南省热区农业气候、土地资源图的编制 总被引:1,自引:0,他引:1
本文采用农业气候分类与土地特征(地貌、坡度)分级相结合的方法编制云南省热区图。这是用一张图,在同一块图斑上同时表示出农业气候和土地两种专业内容特征;按土地和气候的本来面目分型划类,并量算出各类型分区域的土地面积。这是一次新的尝试,以期使科学性和实用性能较好地结合起来。 相似文献
132.
Self-Organizing Maps for Integrated Environmental Assessment of the Mid-Atlantic Region 总被引:6,自引:0,他引:6
A new method has been developed to perform environmental assessment at regional scale. This involves a combination of a self-organizing map (SOM) neural network and principal component analysis (PCA). The method is capable of clustering ecosystems in terms of environmental conditions and suggesting relative cumulative environmental impacts of multiple factors across a large region. Using data on land-cover, population, roads, streams, air pollution, and topography of the Mid-Atlantic region, the method was able to indicate areas that are in relatively poor environmental condition or vulnerable to future deterioration. Combining the strengths of SOM with those of PCA, the method offers an easy and useful way to perform a regional environmental assessment. Compared with traditional clustering and ranking approaches, the described method has considerable advantages, such as providing a valuable means for visualizing complex multidimensional environmental data at multiple scales and offering a single assessment or ranking needed for a regional environmental assessment while still facilitating the opportunity for more detailed analyses. 相似文献
133.
Can machines recognise stress in plants? 总被引:2,自引:0,他引:2
Ronald?Maldonado-RodriguezEmail author Stancho?Pavlov Alberto?Gonzalez Abdallah?Oukarroum Reto?J.?Strasser 《Environmental Chemistry Letters》2003,1(3):201-205
In this paper we show that chlorophyll a fluorescence signals analysed with the self-organizing map (SOM) can be used as a routine tool for the monitoring and classification of pea varieties (Pisum sativum) according to their degree of resistance against drought stress. Fluorescence kinetics measurements were obtained from non-stressed plants. The aim of this study is to evaluate the applicability of artificial intelligence techniques in eco-physiological research. Our goal is to provide a fast tool that will contribute to the knowledge needed to develop strategies that would help to decrease the impact of environmental stress in agriculture and forestry. 相似文献
134.
中国建筑抗震设计规范的演变与展望 总被引:9,自引:3,他引:9
陈国兴 《防灾减灾工程学报》2003,23(1):102-113
地震区划图是编制抗震设计规范的基础资料。本文回顾了中国地震区划图和建筑抗震设计规范的发展简史,对1 956、1977、1990和2001年编制的中国地震区划图进行了简要比较,指出了4代区划图的差异;对1959、1964、1974、1989和2002年编制的中国建筑抗震设计规范或草案的抗震设计原则进行了比较,详细比较了5部规范或草案中关于地震作用的计算方法、场地分类和地基抗震有关规定的异同点,简要讨论了建筑抗震设计规范的发展方向。 相似文献
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With the ever-increasing development of those chemical parks (concentrated areas), the inherent hazards may remain the major leading cause of serious casualties, causing dramatic increases in deaths and injuries. Despite this, proper path beforehand can effectively minimise the number of deaths or injured. In this study, in order to better address the aforesaid issue, the pre-evacuation path planning was adopted to do so. This method can serve to prepare emergency response in case of extreme events, such as fires, explosions, or dangerous leakages, because these accidents could happen in chemical parks (concentrated areas). To that end, a framework was therefore proposed. First, the general risk representation was conducted. After the main hazards as well as the vulnerability within the facilities was identified, the interaction between those two factors could be expressed with matrices. This was followed by the analysis of the domino effect, which tends to occur under such circumstances. Second, individuals' visibility and inclination at each location to choose the nearest exit gate or shelter zone were analyzed by space syntax analysis. Third, a weighted risk map mainly composed of risk, individual's visibility, and inclination of exits was therefore generated. And the lowest cumulative risk path was simulated and analyzed accordingly. Finally, the map modified with received risks suggests that each individual's safest route from their current locations can be possibly simulated with Dijkstra's algorithm, which corresponds to the lowest cumulative risk. For the purposes of illustration and validation, a real case was adopted. The results demonstrated that this framework could provide both technical and theoretical support for the pre-evacuation path planning in chemicals-concentrated areas like chemicals-concentrated areas. 相似文献
138.
Mathematical models used to optimize the process plant layout (PPL) with risk reduction have four primary objectives, which are related to the minimization of land, pumping (pipe system), protection system devices, and risk costs. Moreover, these models are of two types: continuous plane models (CPM) and grid-based models (GBM); however, the nonconvexity of the CPM models makes difficult to achieve the global optimum, because it is formulated as Mixed-Integer Nonlinear Programming (MINLP). Thus, the risk map approach has been implemented with the grid-based models to solve problems of process plant layout focused on finding the best possible solution. However, these risk map formulations present important limitations, mainly related with the use of protection devices and the occupied area. Therefore, a new GBM-MILP formulation is proposed to optimize the selection of protection devices and minimize the occupied area. The risk is reduced through the investment on safety devices instead of considering the increase of separation distances. The proposed model was used to solve the layout problem of an ethylene oxide process, and the results was compared with a process layout reported in the literature. The results show that the model can provide the best possible solution; however, the time spent in the calculation is considerably greater than that reported for continuous plane models. Finally, the model can be used by decision-makers to evaluate different layout options for several explosion scenarios, during the early stages of the plant design. 相似文献
139.
Sven-Erik Gryning Ekaterina Batchvarova Daniel Schneiter Pierre Bessemoulin Heinz Berger 《Atmospheric environment (Oxford, England : 1994)》1998,32(24):993
The state of the boundary layer at the release site during the two tracer experiments is described, based on measurements of atmospheric turbulence carried out by a sonic anemometer, profiles of horizontal and vertical wind by a SODAR as well as frequent radiosonde releases. The boundary layer height is derived from radiosoundings, modelled and discussed. The study is meant as background for discussions of the tracer behaviour near the release site, and possible influence of the local meteorology at the release site on the long-range dispersion. The difference in the initial meso-meteorological conditions between the two experiments is discussed and some of its consequences for the dispersion of the released tracer are clarified. It is concluded that the first experiment is well suited for validation of long-range transport and dispersion models, whereas the second experiment calls for further model development. It is concluded that the micrometeorological measurements are very important as background information for the understanding of plume behaviour on small as well as long scales. 相似文献
140.