共查询到19条相似文献，搜索用时 359 毫秒
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t 型估计是一种新的抗差估计,其思想是以 t 分布对观测误差建模。 但 t 型估计不能抵抗病态性的影响。 因而,为解决病态性与粗差同时存在的问题,需要对 t 型估计进行改进,建立基于 t 型估计的抗差有偏估计。 分别通过有偏估计中的广义压缩变换的方法和对 t 分布模型引入先验信息,可以得到两类抗差有偏估计———广义压缩 t 型(GST)估计和 t 型 Bayes 估计。 详细讨论了正态-Gamma 先验下 t 型 Bayes 估计及其 EM 算法。 理论分析和数值试验都表明,这两种抗差有偏估计可以有效解决粗差和病态性同存在的问题。 相似文献
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针对半参数回归模型求解过程可能出现的法方程病态问题，提出了用岭估计原则改进半参数模型的求解。通过模拟算例将岭估计解法和其他方法进行了比较，结果表明，岭估计解法能较好地解决半参数回归模型求解过程中的病态问题。 相似文献
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为了求解不规则边界面的大地测量边值问题,我国学者提出了虚拟压缩恢复法,并尝试将其应用于航空重力测量数据的向下延拓解算。在对虚拟压缩恢复法进行模型化分析基础上,从理论上证明了在求解地球内部Bjerhammar球上的虚拟重力异常时,虚拟压缩恢复法与基于逆Poisson积分的逐步迭代解是完全等价的,利用数值计算验证了两种解算结果的一致性,同时通过数值仿真计算,分析探讨了数据观测噪声对虚拟压缩恢复法解算结果的影响。检验结果表明,虚拟压缩恢复法应用于航空重力向下延拓计算,一方面可能增加边缘效应的影响,另一方面同样存在数据误差累积放大问题,因此其适用性有待做进一步的研究。 相似文献
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水下声学定位观测数据中不可避免地存在粗差,随机模型解算广泛地采用等权模型,模型实现简单,但与实际不符,且不能抑制粗差影响。针对该问题,提出一种基于IGG3方案的抗差Helmert方差分量估计方法。该方法通过水深和观测距离将观测值分为两类,利用Helmert方差分量估计确定不同类观测值的权比,抗差解决了粗差导致Helmert方差分量估计模型失效的问题。实验结果表明,相比于传统解算方法,抗差Helmert方差分量估计方法可以合理确定各观测值权比,削弱粗差影响,提高水下定位精度和可靠性。 相似文献
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Among the fastest‐growing applications of high‐precision GPS positioning are those which are kinematic in nature. Carrier phase‐based GPS positioning of a moving antenna—for example, attached to a ship, an aircraft, or a land vehicle—is now commonplace. Recent software innovations make use of advanced ambiguity resolution “on the fly” and real‐time kinematic data processing algorithms to emulate the ease of operation of conventional differential GPS (DGPS) based on transmitted pseudo‐range corrections. However, as much higher accuracy must now be assured compared to DGPS, greater attention must be focused on the quality control aspects of GPS positioning. This study describes two methods for detecting failures or changes of small magnitude in real time in GPS measurements. Examination of the overlap or disjointedness of robust and conventional confidence intervals and studentized normal variates have been used as failure detection tools. These methods are based on testing the performance of the differences between the conventional (nonrobust) Kalman state estimates and the robust Kalman filler estimates. Detection of cycle slips in carrier phase data, outliers in phase rate or in code ranges, or any other type of disorder in the measurements of the GPS system can be addressed with these failure detection methods. Application and evaluation of the algorithms has been carried out using raw carrier‐phase and phase‐rate GPS measurements. It has been demonstrated that these failure detection tools provide powerful and efficient diagnostics for detecting small changes in the measurements of the GPS system. 相似文献
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The problems of recording the ionospheric response to tropical cyclones (TCs) and the possibilities for detecting such a response
using GPS (Global Positioning System) signals are discussed. Investigations of ionospheric effects of tropical cyclones with
the use of different geophysical methods and technologies of GPS application for remote diagnostics of the ionosphere are
reviewed. The results of investigating the action of tropical cyclones on the Earth’s ionosphere on the basis of measurements
of variations in the total electron content at the global network of ground-based double-frequency GPS receivers are presented.
It is shown that (a) the recording of tropospheric effects in the ionosphere is associated with the difficulties of detecting
weak disturbances and their identification against the general background of variations and with the problems of identification
of sources of such disturbances; (b) geomagnetic storms mask the effects of tropospheric disturbances in the upper ionosphere;
and (c) when identifying the ionospheric effects of tropical cyclones, one must pay the bulk of attention to the search for
the enhancement of the intensity of disturbances in ionospheric parameter variations. 相似文献
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利用GPS高求取正常高的几种拟合方法 总被引：6，自引：0，他引：6
全面系统地研究了GPS点正常高的拟合方法,对平面拟合、二次多项式拟合、移动曲面拟合、多曲面拟合的GPS水准拟合方法,采用不同参数进行了论述。并结合实际测区,对GPS水准点进行了计算分析。提出了不同测区、不同地形、不同大地水准面的拟合方法,部分拟合方法已用于实际生产中,结果表明,这些方法是切实可行的。通过计算分析,得出结论：不同地形、不同面积的测区需要采用不同的拟合模型,并且拟合时采用的参数也不同。利用GPS高求定正常高,能够降低劳动强度和作业成本,提高作业效率。 相似文献
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