地理空间数据共享机制研究   总被引：7，自引：0，他引：7  

宋国民  贾奋励 《测绘学院学报》2002,19(2):134-136

地理空间数据是地理信息系统的重要组成部分，是国家空间数据基础设施建设的主体，但地理空间数据的多样性导致了数据共享的困难。文中探讨了产生地理空间数据多样性的原因，分析总结了现有的地理空间数据共享的解决方案，并对地理空间数据共享的发展方向进行了展望。  相似文献   

再论拟准检定法的原理、实施和应用   总被引：2，自引：0，他引：2  

欧吉坤 《测绘工程》2002,11(4):3-6

综合阐述了拟准检定法的原理和特点、研究思路。拟准检定法的关键是如何正确选择拟准观测，文章介绍了初选的复选拟准观测的实施要点。列举了拟准检定法在图相关情况下的相差检测，形变分析中的异常探测以及GPS相位观测的周跳检测和修复等方面的应用例子。  相似文献   

藏北高原陆面过程的模拟试验   总被引：12，自引：1，他引：12       下载免费PDF全文

张宇  吕世华 《大气科学》2002,26(3):387-393

利用NCAR陆面过程模式(Land Surface Model)和1998年"青藏高原能量与水分观测实验"加强观测期(GAME/Tibet IOP)的观测资料对青藏高原地区陆面过程进行了模拟研究.结果表明,在观测资料的强迫下模式能够较好地模拟出地表特征量的变化趋势,深层的土壤温度的模拟对初始场在0℃左右的变化敏感.模拟的感热通量、潜热通量以及地表反射的太阳辐射较观测值偏大.在高原地区地表类型分布状况的真实描述及植被、土壤参数的选取可能是提高该地区效果的首要问题;草地下垫面的陆面特征有待进一步研究;对土壤水热运动的真实描述,及冻土过程的加入对大气环流模式(GCM)跨季节的数值模拟会有所改进.  相似文献   

对流层氮氧化物光化学转化特征研究   总被引：10，自引：0，他引：10       下载免费PDF全文

朱彬  孙照渤  安俊岭 《大气科学》2002,26(4):487-495

应用大气光化学模式研究了日间影响NOx光化学转化率的主要物理化学因子.探讨了在不同NMHC/NOx比值时,NOx光化学特征及其转化产物的变化规律.结果表明,影响NOx转化率的主要因子是阳光辐射强度和NMHC/NOx比值.但在NMHC/NOx比值很低时,光强的增加并不能显著提高NOx转化率.温度和初始臭氧浓度对NOx转化率的影响次之.相对湿度对NOx转化率的影响较小.在不同NMHC/NOx比值下,NOx转化特征和产物有很大区别.NMHC/NOx比值高时,产物中PAN＞HNO3.NMHC/NOx比值中(低)时,产物主要是HNO3,PAN等有机氮不到10%(1%).最后初步比较了模拟和观测的NOy组成.  相似文献   

Comparison of resection–intersection algorithms and projection geometries in radiostereometry     

Niclas Brlin 《ISPRS Journal of Photogrammetry and Remote Sensing》2002,56(5-6)

Three resection–intersection algorithms were applied to simulated projections and clinical data from radiostereometric patients. On simulated data, the more advanced bundle-adjustment-based algorithms outperformed the classical Selvik algorithm, even if the error reductions were small for some parameters. On clinical data, the results were inconclusive.The two different projection geometries had a much larger influence on the error size and distribution. For the biplanar configuration, the position and motion errors were small and almost isotropic. For the uniplanar configuration, the position errors were comparably high and anisotropic, but still resulted in a high accuracy for some motion parameters at the expense of others.The simplified resection–intersection algorithm by Selvik may still be considered a good and robust algorithm for radiostereometry. More studies will have to be performed to find out how the theoretical advantages of the bundle methods can be utilized in clinical radiostereometry.  相似文献   

长螺旋钻孔泵压灌注CFG桩缩径与对策   总被引：1，自引：0，他引：1  

贺为民  尚红  孙铭心  刘明军  常河林 《水文地质工程地质》2002,29(2):62-63,65

CFG桩是水泥粉煤灰碎石桩的简称。长螺旋钻孔泵压灌注CFG桩在层状土层的软硬分界处及软土中出现缩径，通过降低提钻速率和设置降水井点，缩径问题有所缓解，采取复打技术后彻底解决了缩径问题。  相似文献   

中子活化分析在公路交通燧洞水文地质调查中的应用   总被引：1，自引：0，他引：1  

侯新生  贾疏源  王永利  虞修竞  唐光洁  于静 《物探与化探》2002,26(4):293-295

利用中子活化测试结果 ,对岩石及泉水干涸残余物中常量及微量元素的进行分析对比 ,以了解深层岩体有关的地质与水文地质信息  相似文献   

1∶50万地质图数据库的研建   总被引：4，自引：1，他引：4       下载免费PDF全文

张庆合  曹邦功等 《中国地质》2002,29(2):208-213

全国1∶50万地质图数据库以国产软件MAPGIS作为基础平台，以各省（区）区域地质志附图和香港特别行政区1∶20万地质图为基础资料，采用现代地质学、地层学、岩石学等的新理论和新的表示方法，按岩石地层单位、花岗岩谱系单位，侵入岩按时代加岩性编制而成。该库由数字地质图库和地理底图库构成，可按任意空间范围、不同比例尺、不同投影方式和不同地质、地理内容等单项或多项任意检索；通过检索能自动形成具有图例、图外整饰的完整的地质图。  相似文献   

On Continent-Continent Point-Collision and Ultrahigh-Pressure Metamorphism   总被引：4，自引：0，他引：4  

DONG Shuwen  Chinese Academy of Geological Sciences  Baiwanzhuang Ro  Beijing WU Hongling  LIU Xiaochun  XUE Huaimin Institute of Geomechanics  Chinese Academy of Geological Sciences  Beijing Fei Zhenbi 《《地质学报》英文版》2002,76(1):69-80

Up to now it is known that almost all ultrahigh-pressure (UHP) metamorphism of non-impact origin occurred in continent-continent collisional orogenic belt, as has been evidenced by many outcrops in the eastern hemisphere. UHP metamorphic rocks are represented by coesite- and diamond-bearing eclogites and eclogite facies metamorphic rocks formed at 650-800℃ and 2.6-3.5 GPa, and most of the protoliths of UHP rocks are volcanic-sedimentary sequences of continental crust. From these it may be deduced that deep subduction of continental crust may have occurred. However, UHP rocks are exposed on the surface or occur near the surface now, which implies that they have been exhumed from great depths. The mechanism of deep subduction of continental crust and subsequent exhumation has been a hot topic of the research on continental dynamics, but there are divergent views. The focus of the dispute is how deep continental crust is subducted so that UHP rocks can be formed and what mechanism causes it to be subducte  相似文献   

Researches on Plants from the Lower Devonian Xujiachong Formation in the Qujing District, Eastern Yunnan   总被引：1，自引：0，他引：1  

WANG Deming  HAO Shougang  LIU Zhenfeng School of Earth  Space Sciences  Peking University  Beijing 《《地质学报》英文版》2002,76(4):393-407

Fossil plants Hedeia sinica Hao et Gensel 1998, Huia gracilis Wang et Hao 2001 and Guangnania cuneata Wang et Hao are described from the Lower Devonian Xujiachong Formation, the Qujing district, eastern Yunnan, China. They contribute to our knowledge of the flora in this district. Based on the occurrence of common plants (Hedeia, Huia, Guangnania and Zosterophyllum australianum) and their horizons, it is proved for the first time that the mid-lower assemblage of the Xujiachong flora is comparable with the Early Devonian ((late) Pragian) Posongchong flora of southeastern Yunnan and the upper Baragwanathia flora of Australia. In view of this fact and the stratigraphic sequence, the mid-lower part of the Xujiachong Formation is considered to be of (late) Pragian age. Through comprehensive analyses of plant, bivalve and fish assemblages and the lithology, the upper part of the Xujiachong Formation is dated to be of early Emsian age. The Xujiachong flora belonged to the northeastern Gondwana palaeophytogeogr  相似文献