测地主题正反解解算   总被引：8，自引：1，他引：8  

施一民  朱紫阳  方胤祺 《测绘工程》2003,12(1):9-12

由测地坐标系中大地线的微分方程式推导出其微分关系式，得出在地球椭球面上基于测地坐标进行正反解的算法和公式，它与大地主题解算公式相比，更为简捷明了。由实际计算数据表明，对于100km以下的距离解算，它亦能达到相当高的精度。因此测地坐标的点位表述不仅可用于DEM和GIS三维可视化，也可用于三维GIS建模以及空间度量和分析。  相似文献   

影响广西的热带气旋与热带季风的某些关系   总被引：11，自引：1，他引：11  

吴恒强 《气象》2002,28(9):27-32

利用常规的热带气旋气候资料和最近（1998）实施的南海季风试验研究成果资料，统计分析影响广西的热带气旋活动与热带季风爆发迟早，强弱等变异的关系，揭示了一些统计特征，并探讨其中的某些规律，初步分析了热带季风对热带气旋的作用，指出热带季风气流进入热带气旋环流对热带气旋的发展有正贡献。  相似文献   

低纬平均经圈环流异常与海表温度异常关系的诊断分析   总被引：2，自引：0，他引：2  

程亚军  王盘兴  李丽平 《热带气象学报》2002,18(3):193-202

利用NCEP/NCAR的40年大气再分析资料中的月平均经向风速及垂直速度，计算了纬向平均经圈环流的质量流函数，分析了纬向平均的海表温度和纬向平均的经圈环流的气候态及异常态特征，结果表明，（1）南、北半球Hadley环流圈的共同上升支偏于赤道附近的夏半球一侧，与[SST↑-]极大值位置相对应；强下沉支位于冬半球一侧；（2）El Nino事件中低纬[SST]′是异常经圈环流产生的重要外强迫源，但其影响程度受基本气流和[SST↑-]及[SST]′的季节变化和年际差异的影响甚大。  相似文献   

基于路径的地图目标拓扑关系表达方法     

刘荣  毛建华  熊助国  吕开云 《华东地质学院学报》2002,25(4):329-332

在分析图论路径性质的基础上，利用路径之间的拓扑关系，分析了地图中点、线、面目标之间的拓扑关系，并分析了这种表达方法相对于其它的表达方法的优点。  相似文献   

拱形洞室围岩内岩爆的计算机模拟与控制方法          下载免费PDF全文

何思为  卢世杰  向贤礼 《探矿工程》2002,(4):55-57

借用GDA软件来模拟开挖周边的应力重分布，在此基础上，重点分析了拱形洞室的拱顶、拱肩、两侧及底角的应力分布与岩爆的关系。并提出如何依据dσ3/（σ1-σ3）大小与正负来分析和估计岩爆位置，因为应力差σ1-σ3可表征岩石的变形与静态破坏，而最小主应力增量dσ3的大不可表征抵抗这种变形与破坏的能力。结果是拱肩与底角会出现岩爆。分析结果得到了加拿大某矿山的岩爆发生位置实际资料所验证。最后，提出了如何利用预裂爆破方法使岩爆从拱肩迁移到洞室底角。  相似文献   

Attenuation modeling of recent earthquakes in Turkey   总被引：1，自引：0，他引：1  

Polat Gülkan  Erol Kalkan 《Journal of Seismology》2002,6(3):397-409

This paper deals with the derivation of a consistent set of empiricalattenuation relationships for predicting free-field horizontal components ofpeak ground acceleration (PGA) and 5 percent damped pseudoacceleration response spectra (PSA) from 47 strong ground motion recordsrecorded in Turkey. The relationships for Turkey were derived in similarform to those previously developed by Boore et al. (1997) for shallowearthquakes in western North America. The used database was compiledfor earthquakes in Turkey with moment magnitudes (M_w) = 5 thatoccurred between 1976–1999, and consisted of horizontal peak groundacceleration and 5 percent damped response spectra of accelerogramsrecorded on three different site conditions classified as rock, soil and softsoil. The empirical equations for predicting strong ground motion weretypically fit to the strong motion data set by applying nonlinear regressionanalysis according to both random horizontal components and maximumhorizontal components. Comparisons of the results show that groundmotion relations for earthquakes in one region cannot be simply modifiedfor use in engineering analyses in another region. Our results, patternedafter the Boore et al. expressions and dominated by the Kocaeli andDüzce events in 1999, appear to underestimate predictions based ontheir curves for up to about 15 km. For larger distances the reverse holds.  相似文献   

Simulating spatiotemporal variations of atmospheric CO₂ using a nested hemispheric model     

C Geels  J.H Christensen  L.M Frohn  J Brandt 《Physics and Chemistry of the Earth》2002,27(35):1495-1505

A three-dimensional Eulerian nested model for transport, diffusion, and surface fluxes of CO₂ has been developed. The model is used to study the spatial and temporal variations of atmospheric CO₂ concentrations as a step towards a better understanding of the regional source pattern over Europe. The influence from the national surface characteristics, as e.g. fossil CO₂ emissions or ecosystem fluxes, can be treated on a continental or national level in the model. In the future the model can be used as a mean to corroborate national and EU-wide controls or reductions of carbon emissions. One of the major questions in the estimation of e.g. national CO₂ budgets is the quantification of surface ecosystem fluxes. In order to test the sensitivity of atmospheric CO₂ concentrations to ecosystem fluxes, two different parameterizations [J. Geophys. Res. 92 (1987) 2999] and [Global Biogeochem. Cycles 10 (1996) 269] have been implemented in the model. The model both with and without nest is validated by comparison with measurements and the different model results will be discussed. The results show that including a nested domain with higher spatial resolution significantly improves the model performance in some areas. In spite of regional deviations in the two sets of ecosystems fluxes no major differences are seen over Europe as a whole when either of the two parameterizations are included in the model and the results compared.  相似文献   

略论医学地质   总被引：2，自引：1，他引：2  

魏东岩 《化工矿产地质》2003,25(1):41-49

医学地质主要研究地球上的无机物(元素、矿物、岩石等)和有机物(微生物等)对人类、动物和植物的作用和影响。这种作用和影响既包括致病的一面,也包括治病的一面,两者是辩证的统一体。研究表明:砷、汞、氡、石棉、晶质硅等地球物质及沙尘暴等均对人类健康造成危害。而通过对钙、磷等元素与人体骨骼的关系和元素-食物-心血管病关系的分析以及对某些人土食石习惯的探讨都清楚地证明了人体与地球的密切关系。地方病是医学地质研究的重点。我国在地方病防治工作中已取得重要成果。医学地质这一综合性边缘学科有着很大的发展潜力。  相似文献   

Mechanical stratigraphy as a factor controlling the development of a sandbox transfer zone: a three-dimensional analysis   总被引：3，自引：0，他引：3  

Antonio Ravaglia  Claudio Turrini  Silvio Seno 《Journal of Structural Geology》2004,26(12):2269-2283

In thrust belts, fold–fault terminations are common features of the structural architecture and can pose complicated problems to unravel, in particular when two or more terminations are in close proximity. Such terminations usually reflect pre-existing attributes. Amongst the many factors, lateral variations in the mechanical stratigraphy can control along-strike geometry and kinematics of fault-related folds.A displacement transfer zone was produced in a compressional sandbox model by means of two adjacent, mechanically different stratigraphic domains. The experiment allowed two discrete chains to develop in the different domains, so that a complex structural setting occurred in the connecting area. Periclinal folds, oblique thrust fronts and oblique ramps developed in the resulting transfer zone. The interaction between periclines in the transfer zone produced lateral culminations in the folded structures. The analysis of displacement across the structural domains revealed that a significant loss of slip along the faults occurred in the relay zone. In this area, imbricate faulting was partially replaced by layer-parallel shortening. A linear relationship appears to exist between the bed length of the thrust sheet and the related fault slip.  相似文献   

当代美国地理学与可持续发展的理论、实践--基于人地关系论的分析     

税伟  张启春  王山河  冯娴慧 《地理与地理信息科学》2004,20(4):56-60

人地关系论是地理学最基本的理论。可持续发展理论与人地关系论一脉相承，是人地关系论的继承、变革和新发展。该文基于《重新发现地理学》的内容，借助中国地理学者对人地关系论与可持续发展关系的研究成果，以人地关系论来看待有人地关系研究深刻历史基础的美国当代地理学在可持续发展研究中的理论与实践。  相似文献