均方根信息滤波和平滑及其在低轨卫星星载GPS精密定轨中的应用

从均方根信息滤波和平滑的基本原理出发．结合卫星定轨的实际特征．导出了其在精密定轨软件中实现的详细公式；针对均方根滤波的特点，提出了快速高效地探测和修复GPS观测数据中周跳的新方法。利用实测星载GPS数据验证了基于均方根滤波的质量控制算法的可靠性．得到了有益的结果。     

Precise orbit determination for the GRACE mission using only GPS data

The GRACE (gravity recovery and climate experiment) satellites, launched in March 2002, are each equipped with a BlackJack GPS onboard receiver for precise orbit determination and gravity field recovery. Since launch, there have been significant improvements in the background force models used for satellite orbit determination, most notably the model for the geopotential. This has resulted in significant improvements to orbit accuracy for very low altitude satellites. The purpose of this paper is to investigate how well the orbits of the GRACE satellites (about 470 km in altitude) can currently be determined using only GPS data and based on the current models and methods. The orbit accuracy is assessed using a number of tests, which include analysis of orbit fits, orbit overlaps, orbit connecting points, satellite Laser ranging residuals and K-band ranging (KBR) residuals. We show that 1-cm radial orbit accuracy for the GRACE satellites has probably been achieved. These precise GRACE orbits can be used for such purposes as improving gravity recovery from the GRACE KBR data and for atmospheric profiling, and they demonstrate the quality of the background force models being used.     

Efficient satellite orbit modelling using pseudo-stochastic parameters

If the force field acting on an artificial Earth satellite is not known a priori with sufficient accuracy to represent its observations on their accuracy level, one may introduce so-called pseudo-stochastic parameters into an orbit determination process, e.g. instantaneous velocity changes at user-defined epochs or piecewise constant accelerations in user-defined adjacent time subintervals or piecewise linear and continuous accelerations in adjacent time subintervals. The procedures, based on standard least-squares, associated with such parameterizations are well established, but they become inefficient (slow) if the number of pseudo-stochastic parameters becomes large. We develop two efficient methods to solve the orbit determination problem in the presence of pseudo-stochastic parameters. The results of the methods are identical to those obtained with conventional least-squares algorithms. The first efficient algorithm also provides the full variance–covariance matrix; the second, even more efficient algorithm, only parts of it.     

Research on Autonomous Orbit Determination of Navigation Satellite Based on Crosslink Range and Orientation Parameters Constraining

Introduction Thepotentialvulnerabilityofsatellitenaviga tionsystemthatreliesongroundstationsisthat thesystemwouldbreakdownifgroundstations weredestroyed,whichcannotmeettherequire mentofnavigationwarfare[1].Withthedevelop mentofsuchspace basedsystemsasgrou…     

导航卫星的单星定轨

本文对导航卫星的单星定轨进行了初步探讨，针对单星定轨时卫星钟钟差和接收机钟钟差难以处理的特点，提出了定轨的同时解算测站距离偏差和采用平均距离变化率进行定轨两种方案，采用GPS的实测数据试验计算表明，两种计算方案均能初步完成单星定轨任务。     

导航卫星自主定轨中系统误差△Ω和△t的消除方法

为了消除利用星间距离或速度观测值进行自主定轨时可能存在的卫星星座整体旋转和卫星钟差整体漂移的误差，提出利用单点定位的方法来研究并消除上述两项误差。当导航卫星整体旋转△Ω角时，单点定位所求得的测站经度也会偏移△Ω角，据此就能用具有精确地面坐标的控制点来测定△Ω角。当各卫星钟中均舍有系统误差△t时，利用单点定位所求得的接收机钟差中也会出现同样的误差，通过与标准时间比对就能测定△t值。算倒结果表明，该方法是有效的，可行的。     

夯扩桩沉管控制贯入度计算法

通过改造格尔谢万诺夫打桩公式,提供了夯扩桩沉管控制贯入度计算表达式,在此 ,介绍了沉积控制贯入度在夯扩桩设计和施工中的用途,并举例验证。     

钢管高强混凝土叠合柱的抗震性能研究

通过周期性往复试验,研究了钢管高混凝土叠合柱柱的破坏形态,耗能能力、延性、承载力以及各种组成部分共同工作等内容,并与钢管高强混凝土核心柱进行了对比;随后通过计算,讨论了叠合柱中有关参数对其极限承载力和影响;最后给出了叠合柱正截面极限承载力的简化计算方法。     

由土卫九(Phoebe)轨道数值改进求解土星质量

为测定土星质量,对收集到的1905年至2006年期间的686次观测[其中包括182次照相观测和504次CCD(电荷耦合器件)观测]通过数值积分进行拟合来改进土星的暗弱的外卫星Phoebe的轨道,并得到土星系总质量msa的新的测定值:3 497.0-1msun(太阳质量),为更精确地测定土星质量提供了一个有价值的参考值。