三峡永久船闸高边坡开挖三维离散元数值模拟   总被引：12，自引：5，他引：12  

李世海  高波  燕琳 《岩土力学》2002,23(3):272-277

采用面－面接触的三维离散元刚性块体模型，从实测节现面中取出其中的三组，按照其倾向，倾角和节理间距将三峡永久船闸未开挖的区域划分为10^5个离散单元，通过施加力边界条件，给出了与实测初始地应力场接近的数值模拟结果；然后，分4步模拟了永久船闸的开挖过程。计算结果表明：开挖过程会引起节理面出现张开趋势，个别岩体还会沿着节理面滑移。岩体位移的不对称现象较为自然地说明了由节理引起的岩体各向异性特征。  相似文献   

Watershed simulation in a sandy terrain of the Thar desert using GIS   总被引：2，自引：0，他引：2  

P.C. Moharana  A. Kar   《Journal of Arid Environments》2002,51(4):489

The sandy landscape in a desert contains very few stream channels. This poses a problem for delineating watersheds for analysis. Since large-scale topographical sheets of sandy terrain also contain very little information on height, delineation of watersheds from topographical sheets often becomes difficult. In order to find a simple solution to the problem in the Thar desert of Rajasthan, India, the authors used the well-known ARC/INFO software for simulation of height and drainage network using the scarce topographical information for a sandy terrain near Jodhpur. Superimposition of data layers generated from remote sensing and secondary sources validated the simulation results, and suggested suitability of the method for application in similarly handicapped areas.  相似文献   

基于DEM 的数字降水径流模型在黄河小花间的应用   总被引：35，自引：0，他引：35  

吴险峰  王中根  刘昌明  刘晓伟 《地理学报》2002,57(6):671-678

DEM是目前用于流域地形分析的主要数据，在流域地形分析及水质构建等方面形成了比较成熟的算法，基于DEM的水文模拟技术的应用给传统的水文模拟方法带来了根本性的变化，基于栅格型DEM，应用最新引进的WMS专业水文处理软件，结合Arc/info、Areview地理信息系统工具，以黄河小花间（小浪底-花园口区间）卢氏以上流域作为研究区，进行了数字降水径流模型的应用研究。  相似文献   

基于数字高程的波束遮挡订正及在雷达定量估测降水中应用     

陈婉婷  何建新  史朝  马建立  林青云 《气象科技》2020,48(1):9-14

地形的起伏使雷达波束受到严重的遮挡,使回波数据质量受到很大干扰。本文使用SRTM任务的DEM数据和谷歌公司的DEM数据分别计算了位于北京南郊的S波段雷达低仰角的波束遮挡率,建立了部分遮挡区域的回波反射率订正关系,并在2018年5月19日北京一次大范围层状云降水过程中,对波束遮挡订正前后的雷达定量估测雨量与地面3个雨量计观测结果进行了定性与定量化对比分析。结果表明:①波束遮挡订正有助于改善反射率因子的空间连续性。波束遮挡订正后的仰角0.5°的反射率与1.5°的反射率之间的差值整体呈现缩小特征,符合层状云降水垂直廓线特点。②09:00—11:00,相比波束遮挡订正前的雷达定量估测雨量(QPE),波束订正后的QPE准确性得到改善,使用分级标准误差与归一化平均偏差评价波束遮挡订正前后QPE与雨量计实测值之间的误差,波束订正后的反射率估测雨量与雨量计实测雨量一致性更好。  相似文献   

关于新一代激光雷达系统   总被引：8，自引：0，他引：8  

刘燕京 《测绘科学》2003,28(1):59-60

激光雷达系统配备有当今世界上最高分辨率的彩色数码相机和多光谱航拍相机。它同时集常用测量装置和全球定位装置于一身 ,当飞机机载该装置飞越地球表面时 ,它们能在获取所需图像及数据的同时 ,计算出传感器的精确位置和取向 ,给出数字高程图 (DEM)及全数码彩色影像。数码相机的底部配备着一个超大像幅的CCD传感器。该激光雷达系统还配置有一个高分辨率多光谱成形相机 ,因此多谱段像素直接与XYZ坐标值相对应 ,得以自动清晰地区分道路、建筑、树林、河流和其他地貌  相似文献   

数字高程模型在坡耕地调查中的应用   总被引：6，自引：0，他引：6  

郭鹏  孙艳玲  白洁  刘洪斌  武伟 《国土资源遥感》2003,14(4):59-62

以1:1万比例尺地形图(H-48-72-24)为例,采用地理信息系统软件Arc/Info数字化地形图生成数字高程模型,并通过DEM计算派生出坡度图,再结合土地利用现状图和相关资料,应用地理信息系统空间分析功能,自动提取坡耕地数据。整个过程主要由计算机进行处理,人工干预少,效率高。  相似文献   

The accuracy of a river bed moulding/casting system and the effectiveness of a low-cost digital camera for recording river bed fabric     

Jim H. Chandler  Tom Buffin-Bélanger  Steve Rice  Ian Reid  David J. Graham 《The Photogrammetric Record》2003,18(103):209-223

Digital photogrammetry has been used to develop and test an artificial river bed moulding and casting system, which allows the pebbles within a coarse-grain river bed to be recreated for hydraulic research in a laboratory flow channel or flume. Imagery of both the original streambed and the cast facsimile was acquired using a non-metric Kodak DCS460 digital camera and digital elevation models and orthophotographs were derived and compared to assess the accuracy of the moulding and casting system. These comparative tests proved to be critical in modifying and developing the system.
Additional imagery was obtained in the field using a non-metric Olympus C3030 'compact' digital camera to assess whether far cheaper camera technology could deliver data appropriate for such comparative examinations. Internal calibration parameter sets and data that were generated were compared with data obtained by the non-metric Kodak DCS460. These tests demonstrate that digital sensors built around high-quality 35 mm professional camera bodies and lenses are required for comparative examinations and for similar system development.  相似文献   

Mapping from ASTER stereo image data: DEM validation and accuracy assessment   总被引：5，自引：0，他引：5  

Akira Hirano  Roy Welch  Harold Lang   《ISPRS Journal of Photogrammetry and Remote Sensing》2003,57(5-6):356

The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on-board the National Aeronautics and Space Administration's (NASA's) Terra spacecraft provides along-track digital stereo image data at 15-m resolution. As part of ASTER digital elevation model (DEM) accuracy evaluation efforts by the US/Japan ASTER Science Team, stereo image data for four study sites around the world have been employed to validate prelaunch estimates of heighting accuracy. Automated stereocorrelation procedures were implemented using the Desktop Mapping System (DMS) software on a personal computer to derive DEMs with 30- to 150-m postings. Results indicate that a root-mean-square error (RMSE) in elevation between ±7 and ±15 m can be achieved with ASTER stereo image data of good quality. An evaluation of an ASTER DEM data product produced at the US Geological Survey (USGS) EROS Data Center (EDC) yielded an RMSE of ±8.6 m. Overall, the ability to extract elevations from ASTER stereopairs using stereocorrelation techniques meets expectations.  相似文献   

陡倾角反倾层状岩质边坡变形特征数值模拟验证   总被引：1，自引：0，他引：1  

金仁祥  任光明 《中国地质灾害与防治学报》2003,14(2):35-38

对于大量中、小型岩质边坡，因地质结构简单、边界条件清楚，且施工周期较短、经费有限，不可能也没有必要对其开展较大规模勘探工作。而物理模型试验则周期较长、费用较高。因此，数值模拟技术可以替代模型试验，成为这类边坡变形破坏分析的首选手段之一。论文利用离散单元方法(DEM)分析了某公路陡倾角反倾岩质边坡开挖变形破坏机制及其演变过程，验证了教科书上该类边坡的机理，并在此基础上提出了边坡防治工程建议。该方法加深了对边坡变形的认识，节约了工程周期及造价，应成为中、小型岩质边坡研究的辅助措施。  相似文献   

Hypergraph—based Object—oriented Model and Hypergraph Theory for GIS   总被引：1，自引：0，他引：1  

ZHANGJin GONGJianya 《地球空间信息科学学报》2002,5(1):37-43

This paper discusses the features and relevant theories of GIS spatial data model based on hypergraph,etc.The integrated concept model based on hypergraph and object-oriented model(HOOM) is proposed by the authors.The principal contribution of this paper is that we study the K-section and other theories of hypergraph.An application example using HOOM is given at the end of the paper.  相似文献