The architecture of a multi-tiered virtual observatory     

Todd King  Jan Merka  Raymond Walker  Steven Joy  Tom Narock 《Earth Science Informatics》2008,1(1):21-28

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短基线GPS控制网双差整周模糊度的直接解算方法     

廖远琴  邱蕾 《上海国土资源》2008,(4)

短基线GPS控制网双差整周模糊的直接解算方法(DC,D irect Calcu lation算法)可以避开"周跳的探测与修复"和"整周模糊度的搜索固定",是一种新的整周模糊度解算方法。在基线坐标满足一定条件的情况下,可以保证解算的L1,-1和L-3,4双差整周模糊度的浮点解与整数解之间的偏差小于0.5周,由浮点解直接四舍五入,进而可以直接解算L1双差整周模糊度。本文用自编软件解算了实测数据,验证了本文方法的实用性,并可获得与商用软件TGO精度相当的基线。  相似文献   

Spreading change of Africa–South America plate: insights from space geodetic observations     

Shuanggen Jin  J. Wang 《International Journal of Earth Sciences》2008,97(6):1293-1300

The results derived from geological data show that the half-spreading rate between the African and South American plates has remained relatively constant at 2 cm/year over the past 80 million years (Silver et al. in Science 279:60–63, 1998). In this paper, we have reestimated a new relative angular velocity of Africa–South America plates using the selected space geodetic station data through a new method. Our angular velocity estimates the spreading rates of Africa–South America plate over several years that are similar in azimuth but significantly slower in rate than the NUVEL-1A predictions averaged over the past 3 million years. The implied rates of deceleration coincide with longer-term trends over the past 35 million years and may reflect the effects of plate interaction and coupling of Africa–South America plates. An erratum to this article can be found at  相似文献   

Environmental problems and geological implications derived from evaporite dissolution in the Barbastro salt anticline (NE Spain)     

P. Lucha  F. Gutiérrez  J. Guerrero 《Environmental Geology》2008,53(5):1045-1055

The halite-bearing Barbastro Formation crops out in the core of the Barbastro Anticline (Ebro Tertiary Basin). This anticline is traversed perpendicularly by some of the most important Pyrenean drainages such as the Cinca and Noguera-Ribagorzana Rivers. The terrace sequences of these fluvial systems have been used as markers to identify and assess dissolution-induced subsidence and salt tectonics. In the limbs of the anticline, terrace deposits underlain by detrital bedrock do not show any evidence of deformation and have a consistent thickness of less than 10 m. The deposits of certain terrace levels of the Noguera-Ribagorzana River and its tributary, the Lo Reguer Creek, are locally thickened filling basins generated by dissolution-induced synsedimentary subsidence up to several kilometers long and more than 100 m deep. Conversely, terraces of the Cinca River do not show anomalously high thicknesses, but local uplifts related to differential upward flow of the halite-bearing bedrock. Locally, a minimum uplift rate of 0.3 mm/year has been estimated from a 64-ka terrace tilted away from the valley. The subsidence hazards occur chiefly in areas where the ground receives artificial water recharge. Serviceability of some canals has been notoriously affected by evaporite karstification. The problem has been mitigated to acceptable levels by grouting. Numerous buildings of Ivars de Noguera are severely damaged by dissolution subsidence, and possibly, by hydrocompaction of gypsiferous silts. The pipe network has been replaced to ameliorate the subsidence risk. In the Cinca River valley, cavities with a total volume of about 180,500 m³ have been created by solution mining at depths greater than 500 m. No investigation methods are applied in the brine field to monitor the distribution and evolution of artificial voids. Substantial increase in salinity of the Cinca River is another evidence of subjacent evaporite dissolution.  相似文献   

基础设施与人类生存环境之关系研究   总被引：18，自引：4，他引：18  

金凤君 《地理科学进展》2001,20(3):276-285

人类在其发展中倾注了大量的人力、物车、财力建设基础设施，希图构筑理想生存环境。但基础设施为人类带来了什么？对人类的发展产生了何种影响？如何认识基础设施在人类生存环境演化中的作用？本文从积极角度阐述了基础设施与人类生存环境之关系，透视了基础设施在活动空间扩展、资源共享和生存环境优化方面的作用与意义。  相似文献   

一种二度体单一界面的空间域重力迭代反演方法   总被引：1，自引：0，他引：1  

高艳 《东北地震研究》1997,13(3):10-16

对二度体单一密度界面的空间域求解提出了一种改进的迭代反演方法。通过详细的改正求得深部重力异常。  相似文献   

利用空间VLBI技术建立参考系及联系     

郑勇  钱志瀚 《测绘学院学报》1992,(3)

本文首先介绍了目前国际上空间VLBI的基本情况,进而对空间VLBI技术在参考系的建立和联系方面潜在的应用前景进行了初步的探讨。  相似文献   

青林省含铁地下水的分布与处理措施     

滕继奎 《吉林地质》1992,(4)

本文根据含铁地下水的形成条件将吉林省含铁地下水划分为四个区,并论述了各区的分布特征。综合国内目前各种地下水除铁技术,着重对各除铁系统的方法、基本原理和适用条件以及经济效益等进行了论述。从环境水文地质学的角度,提出了在含铁地下水区寻找低铁地下水的方法,并通过实例验证是可行的。  相似文献   

日食电离层效应   总被引：7，自引：4，他引：7       下载免费PDF全文

何友文  龙其利 《地球物理学报》1990,33(4):373-383

本文分析了1987年9月23日日环食期间,我国14个电离层站和1988年3月18日日全食期间两个站的垂测仪和偏振仪记录,并综合50年代以来历次日食电离层效应的观测结果,证实:1.E层和F₁层光食效应明显,F₂层动力学效应显著;2.f₀F₂存在日食日值大于、小于或等于控制日值三种典型情况;3.TEC食变曲线有凹陷和不凹陷两种典型情况,甚至出现日食日值大于控制日值的异常现象. 本文对F₂层和外电离层的动力学特征作了定性讨论,认为:空间等离子体温度急剧下降和沿场扩散是F₂层和外电离层日食效应的最主要因素;而磁赤道上空等离子体的沿场扩散、“喷泉”效应,热层风和全（环）食带方位是影响位于磁赤道异常区各电离层站日食电离层效应的主要因素.  相似文献   

河流稀土元素地球化学研究进展   总被引：30，自引：1，他引：30  

王中良  刘丛强  徐志方  韩贵琳  朱建明  张劲 《地球科学进展》2000,15(5):553-540

河流系统中,稀土元素(REE)受区域地质背景、风化作用、溶液化学以及水与颗粒物相互作用等因素的影响发生分异。河流悬浮物显示轻稀土(LREE)适度富集;河水显示重稀土(HREE)富集,或在HREE富集的基础上又有适度的中稀土(MREE)富集;与其它微量元素相比,REE在河水与颗粒物之间有较小的分配系数(K≈10-6);河流沉积物多显示平坦的REE配分模式。  相似文献