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61.
62.
A GIS-implemented, deterministic approach for the automated spatial evaluation of geometrical and kinematical properties of
rock slope terrains is presented. Based on spatially distributed directional information on planar geological fabrics and
DEM-derived topographic attribute data, the internal geometry of rock slopes can be characterized on a grid cell basis. For
such computations, different approaches for the analysis and regionalization of available structural directional information
applicable in specific tectonic settings are demonstrated and implemented in a GIS environment. Simple kinematical testing
procedures based on feasibility criteria can be conducted on a pixel basis to determine which failure mechanisms are likely
to occur at particular terrain locations. In combination with hydraulic and strength data on geological discontinuities, scenario-based
rock slope stability evaluations can be performed. For conceptual investigations on rock slope failure processes, a GIS-based
specification tool for a 2-D distinct element code (UDEC) was designed to operate with the GIS-encoded spatially distributed
rock slope data. The concepts of the proposed methodology for rock slope hazard assessments are demonstrated at three different
test sites in Germany. 相似文献
63.
Despite vigorous tidal and wind mixing, observations in an estuarine tidal inlet in the Wadden Sea show that during part of
the tidal cycle, vertical stratification and internal waves may still develop. Acoustic Doppler current profiler (ADCP) and
conductivity, temperature, depth observations, collected over the past 6 years at 13 h anchor stations (ASs), reveal that
these occur especially during slack tide, when there is little wind and large freshwater discharge from nearby Lake IJssel.
Measurements with a moored ADCP show that in the same tidal phase, strong cross-channel circulation develops, which may suddenly
reverse circulation sense due to passing density fronts. In the vertically stratified phase that follows after the front passage,
propagating mode-one solitary internal waves are observed. These are resonantly generated during decelerating tidal ebb currents
when the (shear) flow passes a transcritical regime (Froude number equal to 1). A combination of photographs (including one
from the International Space Station), bathymetric data, and ASs data leads to the discovery of yet another source of internal
waves in this area, produced during slackening tide by propagating lee waves that develop over a deep trench. We suggest that
both the cross-channel circulation as well as the (solitary) internal waves may locally be of importance for the (re)distribution
and transport of sediments and nutrients and may influence tidally averaged transports. 相似文献
64.
FY-3D极轨气象卫星作为最新一代的极地轨道气象卫星,其图像数据包含了丰富的植被、河流、山区等地表信息,对陆地资源调查、地表类型变化监测等具有重要作用。但几乎每轨遥感图像大约有2/3区域都被云雾覆盖,无法直接获取云层下的地表信息用于产品应用。本文研究晴空数据合成技术,首次提出反射率最小合成法、植被指数最大合成法和西格玛合成法的3个标准联合运用的晴空合成技术,利用先进的多时次气象卫星遥感数据合成技术,自动生成FY-3D中分辨率光谱成像仪(MERSI-II)250m分辨率晴空遥感数据,较好地实现了云和云阴影的去除,生成的晴空效果良好,具备了后续应用的价值。 相似文献
65.
66.
The Above Ground Biomass(AGB) estimates of vegetation comprise both the bole biomass determined through a volumetric equation and litter biomass collected from the ground.For mature trees,the AGB estimated in phenologically different time periods is directly affected by the litter biomass since the Diameter at Breast Height(DBH) and height(H) of such trees that are used in the estimation of bole biomass would remain unchanged over a reasonable time period.In the present study,we have determined the AGB of Sal trees(Shorea robusta) in two contrasting seasons:the peak green period in October being devoid of lit-ter on the ground and the leaf shedding period in February with abundant amount of litter present on the ground.Estimation of AGB for the month of February included the litter biomass.In contrast,the AGB for October represented only the bole biomass.AGB was estimated for ten different plots selected in the study area.The AGB estimated from ten sampling plots for each time period was re-gressed with the individual tree parameters such as the average DBH and height of trees measured from the corresponding plots.The regression analysis exhibited a significantly stronger relationship between the AGB and DBH for the month of October as compared to February.Furthermore,the correlation between the remotely sensed derived data and AGB was also found to be significantly higher for the month of October than February.This observation indicates that inclusion of the litter biomass in AGB will tend to decrease the re-gression relationship between AGB and DBH and also between the remotely sensed data and AGB.Therefore,these conclusions invite careful consideration while estimating AGB from satellite data in phenologically different time periods. 相似文献
67.
68.
基于新生代活动构造背景的地震重点危险区域综合研究——以安徽为例 总被引:1,自引:0,他引:1
基于地震的发生与断裂的活动性密切相关,为了科学合理并尽可能准确地判定未来地震重点危险区域,以安徽为例,利用由深浅部对比、宏微观构造解析所给出的新生代构造活动性最新研究成果,结合地震活动性资料研究结果,对一些重点部位的地震危险性进行了综合研究。结果表明,根据长时间尺度的地质构造最新研究揭示的活动性较强区域,与根据近代地震活动性资料研究反映的危险性较大区域,呈现较好的一致性特征,从而为未来地震重点危险区域的判定提供了新的较为可靠的依据和方法。 相似文献
69.
1991年2月25日柯坪6.5级地震前,震中附近地区的土层地应力、金属摆倾斜仪等多项前兆观测出现异常变化,说明强震发生前近场灵敏度较低的简陋仪器也能观测到明显的前兆反应。分析、认识这些异常对地震短临预报的决策是有益的。 相似文献
70.
介绍了一种集误码测试仪、数字示波器、调制解调器测试、24位采集器测试4大功能于一体的综合性检测设备,其适用于有线传输、无线传输的各类数字地震台及台网使用。本文阐述了该仪器的工作原理、硬件结构和主要功能。 相似文献