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541.
根据长基线情况下机载GPS动态试验数据在多基准站差分模式下的解算分析,得出利用多基准站差分方法能够有效消减误差提高定位测量精度的结论。同时在本文数据分析的基础上,提出了下一步的研究方向。 相似文献
542.
余宗秋 《测绘与空间地理信息》2012,(6):210-212,215
如今,GPS测绘技术发展日趋成熟,GPS的使用越来越普及。对GPS的测量成果,很多测绘工程人员常常简单地用全站仪比测来检验GPS成果,这种简单的对比方法并不能完全检验出GPS的精度。全站仪所提供的距离通常是平距或斜距,而GPS静态解算或动态测量中提供的坐标通常是经投影变形后的坐标。笔者就全站仪对GPS基线边长检验的理论、方法及所要注意的问题进行探讨。 相似文献
543.
提出一种提高短基线相对精度的测定方法。 试验表明,在测角误差影响等同或小于测距误差影响的情况下,该方法能使短基线的相对精度提高4~6倍。 相似文献
544.
GPS形变监测网基线处理中系统误差的分析 总被引:18,自引:3,他引:18
分析了高精度GPS形变监测网基线处理中系统误差产生的原因,分类及其对基线处理的影响,并在此基础上提出消除和削弱这些系统误差影响的一些原则和算法。 相似文献
545.
The problem of defining geochemical baselines. A case study of selected elements and geological materials in Finland 总被引:3,自引:0,他引:3
Although the term ‘geochemical baseline’ appears in the international geochemical mapping programmes IGCP 259 and 360, it has never been well defined. Several considerations relevant to such a definition are discussed. A geochemical baseline for an element refers to its natural variations in concentration in the surficial environment. Geochemical baselines were studied in Finland by comparing results from regional geochemical mapping programmes based on samples of till, clay and organic stream sediment. The geochemical background changes regionally with the basic geology and locally with the type and genesis of the overburden. Baseline concentrations depend on sample material collected, grain size and extraction method. In Finland, concentrations of potentially harmful elements tend to be higher in fine-grained marine and lacustrine sediments than in glacial till. Concentrations are also systematically higher in the < 0.06 mm fraction than in the < 2 mm size fraction of till samples. Only small proportions of the total heavy metal concentrations in Finnish marine clays are bioavailable. Geochemical baselines are needed for environmental legislation and political decision-making, especially in the assessment of contaminated soil. In many areas of Finland, natural concentrations of several heavy metals exceed the guide or limit values designated for contaminated soils. Thus baselines must always be verified in any assessment of sites for contamination. 相似文献
546.
研究了观测卫星的选择对基线解算质量的影响,介绍了提高基线解算质量的人工选星的基线处理方法,通过人工干预选择卫星,解算结果得到明显改善。 相似文献
547.
河口水Cu2+, Zn2+的分析、形式、分布、毒性与生态环境 总被引:4,自引:1,他引:4
生物毒性实验Cu^2+,Zn^2+等浓度与生物死亡率相关模式表明,海水中加入的Cu^2+,Zn^2+等浓度逐渐增高,生物死主恨率相应增高,同一浓度下,死亡率随时间(24,48,72,96h)的增加逐步增高,实验加入Cu^2+仅1μg/L和Zn^2+仅5μg/L本底浓度时,其毒性即已开始遵循相关模式。因此,比天然水含量仅高1,2倍的Cu^2+,Zn^2+离子的污染及毒性,就足以破坏鱼虾在河口的产卵, 相似文献
548.
OBSERVATION AND INVESTIGATION OF VARIABILITIES OF BASELINE CO2 CONCENTRATION OVER WALIGUAN MOUNTAIN IN QINGHAI PROVINCE OF CHINA*
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In-situ measurement of atmospheric CO2 was made at the top of the Waliguan Mountain(36°17'N,100°54'E,3816 m asl).where the air is not directly affected by the local anthropogenic and natural sources,by using a nondispersive infrared(NDIR)analyzer and following the procedures proposed by WMO.The CO2 in the flask samples collected on the mountain was also analyzed in a laboratory.The measurements uncover the daily,monthly and seasonal variabilities and the baseline level of the CO2 in the air over the "clean" area of Chinese hinterland.Results suggest that the CO2 concentration over the East Asia continent has evident periodical variation,similar to that of global distribution.In 1992,an annual mean baseline CO2 concentration of 356.4 ppm over the continent was obtained.The annual mean value was 357.2 ppm for 1993.Some relationships between the CO2 concentration at Waliguan and the weather conditions,especially,wind speed and direction are found through the observation. 相似文献
549.
J. L. Gras 《Journal of Atmospheric Chemistry》1990,11(1-2):89-106
The meaning of baseline as applied to measurements of CN, at atmospheric monitoring sites such as Cape Grim, is discussed and the idea that a baseline exists only in a statistical sense advocated. Use of the concentration frequency-distribution geometric-mean is proposed as the best measure of CN concentrations. Variations in CN concentrations at Cape Grim for periods greater than 12 months are derived by Kalman filtering the monthly estimates of geometric mean concentration obtained from 1977 to 1987. Significant variations are shown to be present on this timescale with quasi-periodic oscillations in concentration. Some association between major fluctuations and El-Nino Southern Oscillation perturbations in the regional circulation is suggested. 相似文献
550.