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卫星地面轨迹分段拟合确定交叉点的方法研究 总被引:1,自引:0,他引:1
用于消除交叉点测量误差的平差法、高度计海况偏差校正及大地水准面模型的建立等都以轨迹交叉点数据为基础。找到一种高效且精确确定交叉点位置的方法十分重要。本文以Jason-1卫星高度计为例,设计了11种弧段分段类型并据此进行拟合以确定交叉点的精确位置,从获取有效交叉点的数量和效率两方面分析,采用12段的分段拟合方法效果最优。不同倾角卫星地面轨迹会发生变化,分段节点需要根据轨迹曲线特征适当调整。本文分段设计方案及最优分段选取方法对任何倾角的卫星依然适用。 相似文献
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现有的曲线化简算法不能很好地化简具有交叉路口的道路曲线,针对这一问题提出一种基于交叉点的道路曲线化简算法。算法分为预化简和修正化简两个阶段:首先识别并得到曲线上的分段点,利用相邻的分段点作为道格拉斯-普克算法的首尾点对曲线进行化简,得到预化简的结果;然后对于交叉点引入偏差阈值ε,通过判断道路曲线交叉点与化简后交叉点的距离与偏差精度ε的大小关系来确定该交叉点的化简与保留,如果保留或者化简后的道路曲线没有交叉点那么将原交叉点作为分段点对此段曲线进行重新化简。理论分析与实验结果表明,文中算法能够有针对性地保留或化简道路交叉点以及保持曲线化简后的形态特征。 相似文献
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轨道交叉点在标校卫星系统偏差参数、评估卫星载荷性能以及卫星精密定轨方面具有重要作用.针对现有轨道交叉点计算多采用搜索法结合多项式拟合方法,虽能够获取精确交叉点位置但较难分析交叉点整体分布特征的问题,该文从二体问题解析解出发,推导了交叉点概略位置理论计算公式,并分析了不同卫星轨道交叉点特性,提出了基于交叉点函数的计算方法,并用仿真试验数据对本文方法有效性进行了验证.该文方法为分析交叉点概略位置空间分布特性提供了一种思路. 相似文献
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高山区高等级公路GPS测高的分段拟合及精度分析 总被引:1,自引:0,他引:1
结合实例,提出高山区高等级公路GPS高程进行分段拟合的方法,对拟合结果进行精度分析,认为该方法能有效提高GPS高程拟合精度. 相似文献
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交叉点快速搜索是海空重力测量数据质量评定的前提和基础。随着海空重力测网规模的不断扩大和不规则测线的出现,现有的交叉点搜索方法无法保证快速、精确地搜索到所有交叉点。引入四叉树分解方法来遍历测网交叉点,实现了交叉点附近的自动加密剖分;利用遍历比较大小取出主、副测线包络矩形的重合区域,取出的索引和实际交叉点数量相当,有效避免了大量的冗余计算。实验结果表明,该方法对于十万测点级别的美国EN01数据块,只要0.28 s即可完成搜索,对于数百万测点的测网的搜索效率也大幅优于常规方法和成熟商业软件。该方法利用遍历搜索保证了100%的准确率,同时具有很高的搜索效率,普遍适用于海空重力测网的交叉点搜索。 相似文献
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《International Journal of Digital Earth》2013,6(1):80-87
Abstract Cultures throughout the world are associating with the rivers. People depend upon the rivers and their tributaries for food, water, transport, and many other aspects of their daily lives. Unfortunately, human beings have not calculated the accurate lengths for the great rivers even today. The lengths of the rivers are very different in popular textbooks, magazines, atlases and encyclopedias, etc. To accurately determine the lengths of the principal rivers of the world, the combination of satellite image analysis and field investigations to the source regions is proposed in this paper. The lengths of the Nile, Amazon, Yangtze, Mississippi, Yellow, Ob, Yenisey, Amur, Congo and Mekong, with lengths over or close to 5000 km, were calculated using the proposed method. The results may represent the most reliable and accurate lengths of the principal rivers of the world that are currently achievable. 相似文献
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软科学这一术语是70年代在国外提出的.然而30多年以来,它在国外不仅未得到普遍的承认,而且对软科学的定义也还未能达成大体上一致的共识.而在改革开放后的中国,出于决策科学化和民主化的需要,经过一些领导人的提倡和支持,特别是通过1986年召开的软科学座谈会及1994年召开的全国软科学工作会议,软科学事业得到了蓬勃的发展.据初步统计,截止1998年底全国共有软科学研究机构1224个,研究人员32655人,初步形成了一支较为强大的研究队伍,并取得了数百项覆盖多个领域的研究成果,为支持各级各类的决策发挥了一定的作用. 相似文献
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Tobias Nilsson Benedikt Soja Kyriakos Balidakis Maria Karbon Robert Heinkelmann Zhiguo Deng Harald Schuh 《Journal of Geodesy》2017,91(7):857-866
The very long baseline interferometry (VLBI) Intensive sessions are typically 1-h and single-baseline VLBI sessions, specifically designed to yield low-latency estimates of UT1-UTC. In this work, we investigate what accuracy is obtained from these sessions and how it can be improved. In particular, we study the modeling of the troposphere in the data analysis. The impact of including external information on the zenith wet delays (ZWD) and tropospheric gradients from GPS or numerical weather prediction models is studied. Additionally, we test estimating tropospheric gradients in the data analysis, which is normally not done. To evaluate the results, we compared the UT1-UTC values from the Intensives to those from simultaneous 24-h VLBI session. Furthermore, we calculated length of day (LOD) estimates using the UT1-UTC values from consecutive Intensives and compared these to the LOD estimated by GPS. We find that there is not much benefit in using external ZWD; however, including external information on the gradients improves the agreement with the reference data. If gradients are estimated in the data analysis, and appropriate constraints are applied, the WRMS difference w.r.t. UT1-UTC from 24-h sessions is reduced by 5% and the WRMS difference w.r.t. the LOD from GPS by up to 12%. The best agreement between Intensives and the reference time series is obtained when using both external gradients from GPS and additionally estimating gradients in the data analysis. 相似文献
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In this letter, we are trying to resolve the electromagnetic problem for the movements of the superconducting particles of the protoplanetary cloud in the magnetic field of Saturn. The force of levitation (Meissner-Ochsenfeld phenomenon) is introduced to the field of planetary science for the first time. It is shown from our theoretical analysis that rings of Saturn might have a superconducting origin, and rings might levitate within magnetic equator plane of the planet. 相似文献
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根据残差二次型次小与最小之差进行整周模糊度确认的关键是差值的分布,只有得到了合理的差值分布才可确定合理的界值.文中基于原有的两种方法及这两种方法的不足,从理论上导出了满足条件的差值分布,并作了一定的说明. 相似文献