三线阵CCD卫星影像的模拟研究   总被引：5，自引：1，他引：5  

江万寿  张剑清  张祖勋 《武汉大学学报(信息科学版)》2002,27(4):414-419

在讨论从给定的DEM和相应的正射影像模拟三线阵CCD卫星影像的原理和方法的基础上，通过模拟影像考察两种卫星影像近似核线的适应能力和地球自转效应对同轨立体成像能力的影响，并讨论了从DEM和正射影像确定投影响中心轨迹、姿态模拟、共线方程和影像生成等细节。通过试验验证了模拟影像的正确性，揭示了两种核线定义存在的问题及其改进方法。  相似文献   

Oracle Spatial 在GIS中的应用   总被引：8，自引：0，他引：8  

曹云刚  范东明 《四川测绘》2002,25(4):167-169,173

本文介绍了Oracle数据库系统中对空间数据存储的解决方案，并针对对象关系模式下空间数据的存储和管理，结合自己的实际工作体会提出了一些具体的解决方法。  相似文献   

土的可恢复剪胀的一种解释     

刘元雪  施建勇 《岩土力学》2002,23(3):304-308

从土的各向异怀角度对土的可恢复剪胀现象进行了解释。基于各向异性情况下的土体弹性本构关系理论分析，认为土的可恢复剪胀现象可部分归因于土的各向异性引起的弹性剪胀。借助有关土体弹性参数实验结果，研究了应力诱导各迥异性对土体弹性剪胀的影响，结果表明：随土体应力诱导各向异性的增大，土体的弹性剪胀也增大。从土体弹性剪胀角度研究了土的卸荷体缩条件，认为土体卸荷体缩取决于加载应力路径的应力增量比，给出了土体出现卸荷体缩的区域。  相似文献   

The High Concentration Tails Of The Probability Density Function Of A Dispersing Scalar In The Atmosphere   总被引：1，自引：0，他引：1  

R. J. Munro  P. C. Chatwin  N. Mole 《Boundary-Layer Meteorology》2001,98(2):315-339

The distribution function for concentrations of a scalar pollutant dispersing in the turbulent atmosphere has a finite domain that is bounded above and below. Three methods, based on extreme value statistics, are used to obtainestimates for the upper bound and to describe the high concentration tailbehaviour of the distribution; all three methods are applied to concentrationdata obtained from experimental atmospheric releases. Quantile quantile (QQ)plots are used to assess the goodness of fit of the resulting estimates of thedistribution, and also to compare the performance of the three methods. Thepredicted values for the upper bound are orders of magnitude less than thesource concentration, illustrating that molecular diffusion has a large effecton the high concentrations.  相似文献   

APPLICATION OF A NEW METHOD IN STUDYING THE SCATTERED STAGE-DISCHARGE RELATIONSHIP OF UNSTEADY FLOWS   总被引：2，自引：0，他引：2  

DAI Qing China Institute of Water Resources  Hydropower Research  Beijing  China. 《国际泥沙研究》2001,16(2)

1 INTRODUCTIONThe macroscopic vedation of the stage-discharge relationship of unsteady nows in alluvial rivers is animPortant and comPlex problem. The Jinjiang reach of the Middle Yangtze Xiver swells often and theflood defence of the reach is the most serious. The stage-discharge relationship is the basic featore of theflow characteristics. The three hydrological stahons, Chenglingii station (at the exit of the DongtingLak), Jianll station and Luoshan station, are key stations on the…  相似文献   

地震面波产生的地震动转动分量研究   总被引：7，自引：0，他引：7  

李宏男  孙立晔 《地震工程与工程振动》2001,21(1):15-23

本文利用弹性波动理论对地面转动分量，即瑞利（Rayleigh)波和乐夫（Love)波产生的转动分量进行了研究，给出了相应的计算公式和计算方法，特别注意到面波的散射效应对转动分量的影响，并将这一特性引入到转动分量的求取中，使问题的解决更切合于实际，最后选取实际地震记录，利用得到的公式计算出地震面波产生的转动分量。  相似文献   

质疑粤西北的冰川遗迹   总被引：1，自引：1，他引：1  

刘尚仁  彭华 《热带地理》2001,21(2):183-188

从地貌、沉积物、第四纪地层关系、古气候、古环境等方面论证了广东封开-怀集-带所谓的冰川谷、冰蚀三角面、悬谷、角峰、刃脊、冰半、鼻山尾、冰碛砾石、蛇形丘以及近百万年来发生过3次冰期，是既不符合地学基础理论也不符合野外实际，所以是不确实的，那里没有第四纪冰川遗迹。  相似文献   

Material component to non-linear relation between sediment yield and drainage network development: an flume experimental study     

JIN De-sheng  CHEN Hao  GUO Qing-wu 《地理学报》2001,11(3):271-281

This paper examines the experimental study on influence of material component to nonlinear relation between sediment yield and drainage network development completed in the Lab. The area of flume drainage system is 81.2 m2, the longitudinal gradient and cross section slope are from 0.0348 to 0.0775 and from 0.0115 to 0.038, respectively. Different model materials with a medium diameter of 0.021 mm, 0.076 mm and 0.066 mm cover three experiments each. An artificial rainfall equipment is a sprinkler-system composed of 7 downward nozzles, distributed by hexagon type and a given rainfall intensity is 35.56 mm/hr.cm2. Three experiments are designed by process-response principle at the beginning the Ψ shaped small network is dug in the flume. Running time spans are 720 m, 1440 minutes and 540 minutes for Runs I, IV and VI, respectively. Three experiments show that the sediment yield processes are characterized by delaying with a vibration. During network development the energy of a drainage system is dissipated by two ways, of which one is increasing the number of channels (rill and gully), and the other one is enlarging the channel length. The fractal dimension of a drainage network is exactly an index of energy dissipation of a drainage morphological system. Change of this index with time is an unsymmetrical concave curve. Comparison of three experiments explains that the vibration and the delaying ratio of sediment yield processes increase with material coarsening, while the number of channel decreases. The length of channel enlarges with material fining. There exists non-linear relationship between fractal dimension and sediment yield with an unsymmetrical hyperbolic curve. The absolute value of delaying ratio of the curve  相似文献   

Health Risks and Environmental Inequity: A Geographical Analysis of Accidental Releases of Hazardous Materials     

Florence Lansana Margai 《The Professional geographer》2001,53(3):422-434

This study examines the spatial distribution and impact of nonroutine accidental releases of hazardous materials relative to the demographic composition of residents in nearby communities. First, atmospheric dispersion modeling methods are used to delineate the impact zones of worst‐case accidents in two New York counties over the last ten years. Next, using accidental reports for 1997, GIS and statistical operations are used at the census tract level of the two counties to determine whether these incidents disproportionately affected disadvantaged neighborhoods. The results suggest that the areas of high‐impact from accidental releases of hazardous materials are best characterized by a large proportion of families below the poverty line, Hispanics, and other minorities.  相似文献   

丰城三溪峡——东乡石马岭推覆构造是扬子板块与华南板块的直接分界线   总被引：5，自引：0，他引：5  

朱旗展  万浩章 《江西地质》2001,15(4):241-246

扬子板块与华南板以丰城三溪峡－东乡石马岭推覆构造分野。该推覆构造发育在萍乡－广丰深断裂与遂川－德兴深断裂的复合部位，具有可行－逆冲推覆性质。原地系统为扬子地层分区中元古界牛头岭组、高桥组和将军岭组，外来系统是华南地层分区新元古界源里组，分别相当于蓟县系修水组和青白口系上施组同期沉积。根据推覆变形形式、构造岩特征和变形程度，可将推覆体划分为包括糜棱岩亚带、糜棱岩化亚带在内的变形主带和劈理化带。韧性剪切变形与推覆变形同期产生，但影响范围更广泛。  相似文献