Digital mapping of Blakeney Point,North Norfolk     

R. L. Collin 《地球表面变化过程与地形》1997,22(13):1253-1258

This second paper in a short series again presents an up-to-date digital map of a classic British coastal landform, Blakeney Point in north Norfolk, and argues for the wider use of readily available, PC-based graphics software in geomorphological cartography. © 1997 John Wiley & Sons, Ltd.  相似文献   

GE露点仪性能分析     

王晓蕾  苏腾  白晓刚 《气象科技》2014,42(6):973-977

对美国GE露点仪测量性能进行了分析。结合GE露点仪使用过程中遇到的问题,总结了GE露点仪的探头选择、探头安装位置、气密性及流量控制等使用要求。以双压法湿度发生器作为标准装置,对GE露点仪进行了大量静态测试,结果表明:GE露点仪相对湿度测量值偏低;在低温条件下,测量误差较大且分散性较大;随着温度的降低,灵敏度明显降低,测量重复性变差,至-10℃时性能下降明显。该文研究内容,对于认识GE露点仪测量性能,保证其测试准确度和可靠性具有重要意义。  相似文献   

Optimizing the dataset size of a topo-bathymetric survey for Hammam Debagh Dam,Algeria     

Djamel Bengora  Lotfi Khiari  Jacques Gallichand  Noureddine Dechemi  Silvio José Gumiere 《国际泥沙研究》2018,33(4):518-524

The capacity of water reservoirs may be considerably reduced by sediment transport and accumulation. This phenomenon may occur quickly in regions prone to erosion, such as Hammam Debagh Dam region in Algeria. For better management of water resources, it is important to estimate the volume of a reservoir by regular and frequent topo-bathymetric surveys. Topo-bathymetric surveys with a high point measurement density are expensive and time-consuming. To reduce this expense and to increase the frequency of topo-bathymetric surveys, it is required to optimize their size and density. The complete survey of the reservoir created by the Hammam Debagh Dam in Algeria was examined in comparison with 19 reduction subsets using geostatistics. The study showed that the complete dataset of 32,164 points, corresponding to a density of 42 points ha^-1 could be reduced to 10,000 points, i.e. 13 points ha^-1, without affecting the estimation of the water volume in the reservoir. This reduction could considerably simplify the work load, reduce the expenses to do these surveys, and, therefore, allow for an increased frequency of topo-bathymetric surveys.  相似文献   

重力位能同震变化及其构造意义——以青藏高原地区为例   总被引：3，自引：1，他引：2       下载免费PDF全文

周江存  孙和平  徐建桥  崔小明  陈晓东 《地球物理学报》2017,60(6):2493-2499

地震除了以地震波的形式释放能量之外,地震还会使地球产生永久变形,该变形将使重力位能产生变化.研究表明,地壳的重力位能的同震变化能够很好地揭示构造活动的拉张或挤压状态.本文首先基于球对称、非自转、弹性和各向同性(SNREI)地球的点源位错理论,提出了一种有效的计算重力位能的同震变化的方法,该方法不仅适用于剪切型地震,而且适用于拉张型地震;然后研究了青藏高原地区在1976-2013年间发生的地震对地壳重力位能的同震变化的影响.结果表明,青藏高原中部和西部的地震使得整个地壳的位能减小,而东部的地震使位能增大;位能的减小和增大对应了该地区构造活动的拉张和挤压状态;并且1999-2013年期间较1976-1998年期间地震对地壳重力位能的影响加剧.  相似文献   

锡林郭勒盟一次暴雨天气过程分析     

董春艳  辛秀芬  许践  刘旭东  董春丽 《内蒙古气象》2011,(5):21-23

对2006年7月17日锡林郭勒盟南部地区及苏尼特右旗的暴雨和大暴雨天气过程进行了天气诊断分析,结果表明:7月17日暴雨的产生是地面倒槽、高低空急流、切变线、副热带高压共同作用的结果。高空500hPa稳定的环流形势为大暴雨的酝酿提供了有利的环流背景,低层切变线、冷空气是暴雨产生的触发条件,而台风低压的滞留为暴雨区提供了源源不断的水汽和动力抬升条件。  相似文献   

Quantifying the spatial heterogeneity of points     

Hua Shu  Ci Song  Ting Ma  Yunyan Du  Zide Fan 《International journal of geographical information science》2019,33(7):1355-1376

Variation in the spatial heterogeneity of points reflects the evolutionary process or mechanism of geographical events. The key to depicting this variation is quantifying spatial heterogeneity. In this paper, the spatial heterogeneity of a point pattern is defined as the degree of aggregation-type deviation from complete spatial randomness. In such a case, a goodness-of-fit-type statistic based on the distribution of nearest-neighbor distances called the level of heterogeneity (LH*) is regarded as a standard measurement, and a normalized version called the normalized level of heterogeneity (NLH*) is proposed for datasets with different point numbers and study region areas. Considering the complex integration calculation of LH* and NLH*, simulation experiments are implemented to test the capability of some classic nearest-neighbor statistics in quantifying spatial heterogeneity. The results showed that except for the standard LH* statistic, only Clark and Evans’ statistic (A-w) and Byth and Ripley’s statistic (H-xw) are robust. Statistics NLH*, (A-w) and (H-xw) are validated by quantifying the spatial heterogeneity of two-dimensional crime events, three-dimensional earthquake events and four-dimensional origin-destination (OD) events. The results indicate that these statistics all have a reasonable explanation in quantifying spatial heterogeneity for real-world geographical events of different types and with different dimensions. Compared with NLH*, Clark and Evans’ (A-w) statistic and Byth and Ripley’s (H-xw) statistic are recommended from the perspective of accessibility.  相似文献   

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郝明  王庆良  崔笃信 《大地测量与地球动力学》2009,29(2):88-91

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基于结构分析的点状地图符号识别   总被引：1，自引：0，他引：1  

张涛  尹永利  刘肖琳 《测绘工程》2000,9(3):15-18

通过对点状地图符号特点及其识别难度的分析,提出了结构分析为主要识别方法,在结构分析中用模糊编号算法对组成符号的基元进行编码,有效地表示出基元的空间位置关系,大大消除了细化和轻微旋转对提取基元的影响,从而提高了识别率。  相似文献   

奥陶纪年代地层学研究评述   总被引：8，自引：6，他引：2  

陈旭  戎嘉余  张元动  樊隽轩 《地层学杂志》2000,24(1):18-26

回顾并评述了近十年来国内外奥陶纪年代地层学研究的进展和存在问题 ,特别论述了奥陶系的系、统、阶 3级全球界线层型剖面点 (GSSP)的研究和选定工作 ,探讨我国地层学家在奥陶系内部在我国再获“金钉子剖面”的可能性和可行性 ,并提出我国奥陶系的统和阶与国际接轨的原则和方法。  相似文献   

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于合理  郝金明  刘伟平  田英国  张鹤 《大地测量与地球动力学》2014,34(1):161-164

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