森林沼泽景观元素存在形式及化探方法研究   总被引：10，自引：9，他引：10  

金浚  丁汝福等 《地质与勘探》2002,38(4):50-55

对我国东北北部森林沼泽景观各种采样介质元素存在形式进行研究，确定这类地区元素存在形式有碎屑形式和元素活动态形式两类。实际资料表明，元素存在形式对采样介质，采样粒度，采样方法的确定有重要影响，对研究区景观地球化学特征，元素迁移富集机制研究和化探异常评价具有重要意义。通过试验研究确定了森林沼泽景观区中大比例尺化探工作方法。  相似文献   

Velocity of small-scale auroral ionospheric current systems over Indian Antarctic station Maitri     

Girija Rajaram  A. N. Hanchinal  R. Kalra  K. Unnikrishnan  K. Jeeva  M. Sridharan  A. Dhar 《Journal of Earth System Science》2002,111(1):51-62

The Indian Antarctic station Maitri (geog. 70‡45’S, 11‡45’E, geom. 66‡.03S, 53‡.21E) occupies a sub-auroral location during magnetically quiet conditions(Σκρ < 10), but attains an auroral position when the auroral oval shifts equatorwards with increasing strength of magnetic disturbance. At the latter times, triangulation with 3 fluxgate magnetometers located at the vertices of a suitable triangle provides a means of monitoring mobile auroral ionospheric current systems over Maitri. The spacing between the magnetometers is typically kept at 75–200 km, keeping in mind the scale-sizes of ∼ 100 km for these mobile current systems. This work reports the results of two triangulation experiments carried out around Maitri in January 1992 and January 1995, both during Antarctic summer. The velocities estimated for pulsations of the Pc4 and Pc5 type were about 0.59 km/sec in the direction 102‡.7 east of due north, in the first case, and about 1–3 km/sec in the second case in the east-west direction. While several magnetometer arrays exist in the northern auroral regions (e.g., the Alberta array in Canada, the Alaskan array in the U.S. and the IMS Scandinavian array), there is no report in literature of triangulation through arrays in Antarctica, except for a one-day study by Neudegget al 1995 for ULF pulsations of the Pc1 and Pc2 type. The velocities obtained for the Pi3 type of irregular pulsations over Antarctica in the present study tally well with those obtained for northern auroral locations.  相似文献   

基于移动通信网络无线定位技术的原理及应用   总被引：3，自引：1，他引：3  

赵军  李先华 《测绘科学》2002,27(3):48-51

无线电定位技术有着广泛的应用前景 ,也是未来第三代移动通信的一个支撑技术。本文介绍了基于移动通信网络无线定位的原理和技术 ,分析了在移动通信系统内实现移动台精确定位的主要技术难点和提高精度的对策  相似文献   

姚安地震序列的震源参数研究   总被引：9，自引：1，他引：9  

刘学军  叶建庆  蔡绍平  张俊伟 《地震研究》2002,25(3):240-245

利用昆明区域数字遥测台网记录的姚安地震序列资料，结合姚安震区流动数字化台网的近震源观测资料，使用波谱分析法测算婉安地震序列的震源力学参数，给出S波的计算结果，并进行讨论。同时，对区域数字遥测台网和震区流动为流动数字化台网同时记录的39个地震采用同一模式计算出的震源参数进行了对比讨论。  相似文献   

关于发展我国地下流体前兆流动观测问题的建议   总被引：3，自引：0，他引：3  

车用太  王广才  刘五洲  刘成龙  王基华  张培仁 《国际地震动态》2002,(11):1-7

介绍了地下流体前兆流动观测及其目的与意义、国内外地下流体前兆流动观测的历史与现状、我国目前存在的主要问题；针对现状与问题，提出了建议我国地下流体前兆流动观测系统的建议，其中包括指导思想、发展目标、观测网的类型与布设、观测点的建议、观测项目与观测仪器的选择、观测工作的组织与实施、观测数据的产出与共享等科学与技术问题。  相似文献   

昆明站流动VLBI观测数据处理初步结果     

贾小林  巨志斌 《测绘学院学报》2001,(2)

对我国自行研制的流动VLBI首次长距离观测数据进行处理 ,得到了初步结果 ,并对流动VLBI今后的观测提出了一些建议。  相似文献   

甘肃张掖盆地含水层岩性,电性及富水性关系研究   总被引：2，自引：0，他引：2  

粟英姿 《矿物岩石》1993,13(4):105-108

本文依据水文地质和测井资料,研究了甘肃张掖盆地含水层岩性、电性及富水性关系和钻孔涌水量分布规律。它为合理利用和开发该盆地地下水资源,提供了新的科学依据。  相似文献   

移动Agent结构化安全机制的研究     

汪治  郭忠文  孟庆春  王伟  陶冶 《中国海洋大学学报(自然科学版)》2003,33(5):740-746

分析了移动 Agent的安全问题和现有的 Agent安全保护技术 ,从重构移动 Agent的结构入手 ,提出了将 Agent的安全机制从功能体中分离出来独立实现 ,从而构建 1种新的移动 Agent的结构化安全机制的方法 ,并对此进行了阐述  相似文献   

The effects of drag reduction by ribbons attached to cylindrical pipes   总被引：1，自引：0，他引：1  

S. H. Kwon  J. W. Cho  J. S. Park  H. S. Choi 《Ocean Engineering》2002,29(15):1945-1958

This study proposes a drag reduction device that uses three ribbons attached 120 degree apart to vertical pipes. Experiments were conducted in a circulating water channel to investigate the effects of the ribbon length and the direction of the flow on various current velocities. Drag on a vertical cylinder was measured by a resistance dynamometer. Flow visualizations were conducted using laser sheet beams. Laser Doppler Velocimetry (LDV) was used to measure the velocity field in the wake. This experiment demonstrates that attached ribbons can be used to reduce the drag force on vertical pipes for various directions of incoming flows. The ribbon-type device is very simple and easy to fabricate for field applications. The results are promising for the application to offshore structures.  相似文献   

Wave energy losses in intermediate depths     

Denis Mollison 《Applied Ocean Research》1983,5(4):234-237

Recent work on wave power devices has encouraged interest in the processes whereby waves lose energy and change direction in shoaling water, and especially in detailed calculations of their effects.^1,2 Here one of the most comprehensive sets of measurements available is examined, for four sites in depths of 15 to 100 m off South Uist in the Hebrides. The mean directional spectrum is recalculated for each site, and a proper allowance found for refraction which raises the estimates of net energy flux in intermediate depths by up to 10%. Indeed, the pattern of losses between 100 m and 23 m depths fits well with that expected from bottom friction. The estimated friction coefficient is quite high, as might be expected in view of the very rough sea bottom in the area.³  相似文献