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排序方式: 共有1906条查询结果,搜索用时 15 毫秒
281.
郭乐  王家鼎  刘涛 《地下水》2009,31(3):102-103,106
以不平衡推力法为基础,同时考虑不同烈度、不同地震力作用方向条件下黄土滑坡的稳定性评价,以宁夏西吉回回川滑坡为例,进行了滑坡稳定系数 K 与地震系数 KS,与地震作用角度β的关系及滑坡稳定性敏感性分析.结果表明地震最危险作用方向与水平方向有一定夹角倾向坡外,且随地震系数增大而增大.黄土滑坡稳定性评价中应该考虑地震最危险作用方向.  相似文献   
282.
The coevolution between supermassive black holes(SMBHs)and their host galaxies has been proposed for more than a decade,albeit with little direct evidence about...  相似文献   
283.
This article presents a deterministic model for sub-block-level population estimation based on the total building volumes derived from geographic information system (GIS) building data and three census block-level housing statistics. To assess the model, we generated artificial blocks by aggregating census block areas and calculating the respective housing statistics. We then applied the model to estimate populations for sub-artificial-block areas and assessed the estimates with census populations of the areas. Our analyses indicate that the average percent error of population estimation for sub-artificial-block areas is comparable to those for sub-census-block areas of the same size relative to associated blocks. The smaller the sub-block-level areas, the higher the population estimation errors. For example, the average percent error for residential areas is approximately 0.11 percent for 100 percent block areas and 35 percent for 5 percent block areas.  相似文献   
284.
基于非物质文化遗产旅游资源要素价值、影响力、保护价值及生态敏感度4个目标层19个指标,利用AHP方法构建非遗旅游资源评价体系.通过对皖东地区旅游直接利益相关者政府、企业、居民及游客进行问卷调查,得出其对非遗旅游资源评分值.政府对非遗旅游资源的评价最高,当地居民和经营者的评价基本相同,游客的评价最低.政府机构是地方非遗开发保护和传承的主导者,应积极引领发挥其最大旅游效益;当地居民和经营者是非遗传承与发展的参与者,应积极提高自身参与非遗保护传承的主动意识;非遗地域差异明显,游客对其相对生疏,建议重点开发能让游客参与其中的非遗旅游活动,不同群体在开发利用非遗旅游资源方面各尽其用.  相似文献   
285.
The mean seasonal hydrography and circulation of the Western Iberian Margin (WIM) are studied by means of a high-resolution configuration of the Regional Oceanic Modeling System. A comparison of 5-year model averages for January and July with climatological datasets shows a general good agreement in the reproduction of the mean water mass properties and hydrographic distribution. We find that there is a prevailing tendency for slope poleward flow at about 80–100 km offshore at all latitudes from the surface to 1,500 m with strong vertical coupling. This northward flow, which is mainly along slope and amounts up to 8–10 cm s?1, exhibits several mean flow recirculation regions on its way and evidences of an offshore pathway of poleward flow. Transports at different zonal sections further confirm the poleward flow tendency with two peaks of poleward transport in summer (3–10 Sv) and winter (2–7 Sv). The transport time series emphasize the seasonal character of the alongshore circulation and the interannual intrinsic variability of the circulation, since the forcing fields are climatological. As a conceptual essay with the purpose of assessing the Mediterranean Water flow influence on the WIM mean circulation, a second model configuration is setup, where the Mediterranean outflow into the study domain is removed. We find that there is an attenuation of the mesoscale field, but the slope poleward flow intensifies and remains as a mean dynamical feature closer to the upper slope.  相似文献   
286.
Abstract

Artificial recharge is a very suitable approach in the overall water resources management of a given area. What are the matter, the purposes and the past of recharge, the factors and the problems to be taken into account, the methods and the economics of this practice? Those are some questions to which the paper tries to give answers. Several examples are quoted as well as two projects in the Middle-East and North Africa.  相似文献   
287.
Geophysical methods were applied for hydrogeological targets in many countries including Vietnam. This paper presents results of using complex geophysical techniques as well as 2D electrical resistivity imaging (ERI), vertical electrical sounding (VES), very low frequency (VLF), and seismic refraction for geological structure investigation for locating the aquifers and assessing the hydrogeological conditions for groundwater potential in industrial zones of North Hanoi, Vietnam. The locations of two aquifers are determined by their depth and thickness on the basis of resistivity and seismic velocity values which were proved by stratifications of three boreholes to 40–60 m of depth on the study area. There are connections from surface water to shallow aquifer by hydraulic windows, as follows from VLF data. The deeper aquifer can be considered as a potential groundwater supply, but the water level is descending in time, as shown by hydrological monitoring. However, with careful use and by reducing sources of pollution, groundwater can continue to be an important natural resource for future.  相似文献   
288.
289.
在分析历史资料和防治现状的基础上引入城市重要性作为判别准则之一,以18个地级市为研究对象利用层次分析法对河南省泥石流危险度分区。依据泥石流危险度权重的不同将河南省分为5个区间,其中危险度大的城市1个,危险度中等的城市3个,危险度小的城市6个,危险度极小城市2个,无危险度城市6个。以期为河南省泥石流灾害的防治提供有益的参考。  相似文献   
290.
在深入探讨皮羌走滑断裂对构造裂缝控制作用的基础上,应用ANSYS有限元方法,模拟区域差应力、走滑断裂宽度和走向等因素影响下构造裂缝分布发育的规律.模拟结果表明,构造裂缝带宽随区域差应力增大呈线性增大,随断裂带宽度增大呈线性减小,随断裂走向与区域差应力夹角增大呈线性减小;施加的区域差应力值是影响构造裂缝发育的主要因素.  相似文献   
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