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排序方式: 共有937条查询结果,搜索用时 93 毫秒
231.
电磁辐射"EMOLS"仪观测结果原理及震例 总被引:10,自引:0,他引:10
“九五”期间研制的“EMAOS”电磁辐射仪,其接收原理是按大地电磁测深的原理改进而研制的。选择接收频段为0.01~10Hz,该频段探测深度在0~20km,是浅源地震发生的层位。记录的电磁扰动是在应力场作用下,动电效应产生的电磁场。电场和磁场同时记录增强了信息可信度的判断能力,记录震例表明,异常规律与已有模拟结果基本相同。因此,已总结的模拟记录预报指标等可在数字记录结果中使用。 相似文献
232.
居住在山区的人们主要活动空间是斜坡。人们对斜坡利用的有效与否是由人们对斜坡认识充分与否决定的。倘若人们对斜坡认识不足,就可能遭受因斜坡失稳所带来的损失。因此,对这类斜坡的稳定状况的正确认识很有必要。以清江流域典型滑坡——瓦屋场滑坡的复活为例,通过介绍清江流域瓦屋场滑坡人类活动与该滑坡产生的变形情况,根据滑坡体工程地质条件,针对变形原因用萨尔玛法及不平衡推力法进行了稳定分析,同时对复活机制进行分析。在此基础上按照顺应性准则和协调性原则,提出相应的工程治理措施。鉴于该滑坡为该地区的典型滑坡,从灾害学角度说明人类在利用坡体前,对坡体稳定状况认识的重要性并给出人们合理利用该地区自然边坡的建议。 相似文献
233.
矿山环境地质调查技术要求研究 总被引:6,自引:2,他引:6
本文提出了矿山环境调查的基本原则就是区域展开、重点突破、吸取前人成果、结合高新技术;将矿山环境调查划分为普通调查、验核调查和解剖调查三大类型;指出3S技术、野外和室内测试试验、长观动态监测和地球物理勘探等是矿山环境调查的主要技术手段和方法;认为调查组织形式和通讯保障系统建设也是决定矿山环境调查质量和水平的关键因素。 相似文献
234.
Defining the distortion of a conformal map projection as the oscillation of the logarithm of its infinitesimal-scale σ, Chebyshev’s principle states that the best (minimum distortion) conformal map projection over a given region Ω of the ellipsoid is characterized by the property that σ is constant on the boundary of that region. Starting from a first map of Ω, we show how to compute the distortion δ0(Ω) of this Chebyshev’s projection. We prove that this minimum possible conformal mapping distortion associated with Ω coincides with the absolute value of the minimum of the solution of a Dirichlet boundary-value problem for an elliptic partial differential equation in divergence form and with homogeneous boundary condition. If the first map is conformal, the partial differential equation becomes a Poisson equation for the Laplace operator. As an example, we compute the minimum conformal distortion associated with peninsular Spain. Using longitude and isometric latitude as coordinates, we solve the corresponding boundary-value problem with the finite element method, obtaining δ0(Ω)=0.74869×10−3. We also quantify the distortions δl and δutm of the best conformal conic and UTM (zone 30) projections over peninsular Spain respectively. We get δl=2.30202×10−3 and δutm=3.33784×10−3. 相似文献
235.
介绍了一种基于测距信号强度最大原理进行目标的自动搜寻、照准与测量的基本工作原理、方法与实现过程,分析了其适合于作为固定站用于无人看守的危险地区的长期变形监测。 相似文献
236.
Michael Mutz Herve Pigay Kenneth J. Gregory Dietrich Borchardt Michael Reich Klaus Schmieder 《Limnologica》2006,36(2):110-118
Dead wood is a significant element of natural streams and rivers in temperate climate zones. Established stream management removes wood, whereas some scientists recently promoted the reintroduction of wood in stream rehabilitation and restoration. It is desirable to know if wood in streams and rivers would be accepted. A survey was therefore conducted in order to assess the spontaneous visual perception of 10 stream and 10 river scenes with and without wood in terms of naturalness, risk, aesthetics and need for improvement using visual analog scales. Three hundred and sixty-five German students from five subjects related to water management and from one subject without any professional association to running waters were surveyed before their first contact to teaching of aquatic ecology. They clearly perceived wood in streams and rivers as natural. Scenes with wood were most frequently associated with danger for sport activities while scenes without wood were most frequently associated with danger by flooding. When comparing scenes with and without wood, scenes with wood were clearly considered more positive as significantly more aesthetic, less dangerous and needing less improvement. The disciplinary groups showed variations in the absolute evaluation scores but the relative evaluation of scenes with wood versus scenes without wood was similar among all groups. The results indicate an acceptance for the reintroduction of wood in stream rehabilitation and restoration by young students who are potential future players in water management. 相似文献
237.
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239.
通过郑州市公安地理信息系统中电子地图组成的介绍,初步探讨了交互环境下电子地图的作用、种类及其设计的基本原理,并总结了郑州市公安地理信息系统中电子地图的设计特点及其功能。 相似文献
240.
The paper studied the distribution law of Xinjiang's heavy rain in time-area-depth bytheoretical expression deduced from the entropy maximum principle and found some regularities ofheavy rainfall in Xinjiang based on analyzing 32-year observational data from about 400hydrological and meteorological stations.It has practical significance for studying Xinjiang's heavyrainfall,designing water conservancy and reducing flood catastrophe caused by heavy rain. 相似文献