相位求差法与多项式拟合法探测修复周跳的比较

目前对相位观测值周跳的探测和修复已有多种方法,但是各种方法都不是很完善。通过用相位观测值相邻历元求差法和多项式拟合法对周跳进行探测和修复,算例结果表明相位观测值相邻历元求差法不仅能准确地锁定发生小周跳的历元,而且能高效地修复观测值。该方法执行效率高,实用性强,尤其适合动态定位的应用。     

GNSS气象探测技术及其应用

GNSS气象探测是一个崭新的极具潜力的研究方向。介绍了GNSS气象学的基本概念,重点阐述了GNSS气象学的基本原理以及在天气预报、全球气候和环境监测、高空风探测、空间天气预警等领域的应用,并指出了存在的问题。     

双因子抗差贝叶斯估计及其在GIS数据采集质量控制中的应用

在对GIS扫描数字化过程中,所采集的数据里经常含有系统误差和异常误差。在纠正这些误差的过程中,应同时考虑控制点坐标和数字化坐标的先验协因数。文中以数字化的系统误差拟合模型为例,提出双因子抗差贝叶斯估计误差拟合方法,并分别就控制点含有粗差、数字化点含有粗差和两者均含有粗差3种情况建立相应的模型,实例验证了其抗差效果。     

A Bayesian method for linear, inequality-constrained adjustment and its application to GPS positioning

One of the typical approaches to linear, inequality-constrained adjustment (LICA) is to solve a least-squares (LS) problem subject to the linear inequality constraints. The main disadvantage of this approach is that the statistical properties of the estimate are not easily determined and thus no general conclusions about the superiority of the estimate can be made. A new approach to solving the LICA problem is proposed. The linear inequality constraints are converted into prior information on the parameters with a uniform distribution, and consequently the LICA problem is reformulated into a Bayesian estimation problem. It is shown that the LS estimate of the LICA problem is identical to the Bayesian estimate based on the mode of the posterior distribution. Finally, the Bayesian method is applied to GPS positioning. Results for four field tests show that, when height information is used, the GPS phase ambiguity resolution can be improved significantly and the new approach is feasible.     

基于小波变换的周跳探测与修复

探测和修复周跳一直是GPS定位中的关键问题。利用小波变换对相位减伪距观测量进行周跳探测。首先介绍小波变换周跳探测的一般方法,然后在此基础上提出改进。改进方法可以对周跳进行探测和直接修复,进而探测和修复多次周跳,同时有效地克服一般方法可能出现探测失误的缺点。这种改进方法的效果在实验中得到验证。     

一种双频载波相位周跳探测与修复方法

针对相位减伪距法只能探测出大周跳而对小周跳无能为力的问题,提出将相位减伪距法应用于双频载波相位周跳的探测与修复中。对采样率为1s、15s和30s不含周跳的观测值分别加入1周到40周不等大小的周跳,采用相位减伪距法分别对加入周跳的观测值进行处理。结果表明,该方法对于采样率为15s和30s的观测值仍然保持其优秀的大周跳探测能力,对采样率为1s的载波相位观测值则能够探测出小于1周的周跳,且其周跳探测分辨率能达到0.3周的高周跳分辨率。与其他周跳探测方法相比,该方法需要的信息量和计算量更小,效率高,算法易于计算机实现,且具有很强的实用性。     

监测数据小波方法的回归估计及应用

提出一种基于小波分析和回归估计的变形预测模型,基本思想是根据小波分析的优点,对监测数据进行小波分解,通过对小波系数进行估计得到回归估计函数。由于在小波分解过程中对小波系数作用于阈值,即对监测过程受到的干扰进行了消除或降低,从而使建立的预测模型更接近于变形体规律,预测更准确。实例计算表明,这种模型是切实可行的。     

The inverse problem of optimal regulators and its application

1 IntroductionThe inverse problem of oPtirnal regulators is tofind a suitable quadratic ast function fOr a lineartime-invariable system with constant but unknowndisturbance so that the optimal control law canmeet the requirements of relative stability. Inl984,Juang and Lee presented a methed of OPtitnalPOle assignrnent in a sPecified region. In l986, Leeand Liaw presented a new methed for finding theweighting matrices Q and R of inverse regulatorswithout soution of the Ricatti equation. …     

基于摄影测量系统的岩体结构面精细识别表征及应用

岩体结构面的识别和特征参数的表征对于岩体特性及失稳机制研究具有重要的基础意义。本文基于无人机航测、GPS-RTK,以及地面近景摄影组成的摄影测量系统对甘肃北山不同尺度岩体结构面进行了系统性研究。利用不同视角摄影得到的地物照片建立了场区数字正射影像模型和露头三维重构数字表面模型,通过数字化的识别和统计方法实现了岩体结构面信息的有效解译和特征参数的表征。对典型露头和区域的研究结果表明,采用的摄影测量系统可从不同维度和尺度进行岩体结构面的精细化调查和识别。根据结构面特征参数的变异性,对场区大断裂F31断层的断裂影响带进行了评估,初步得到F31断层对上盘岩体完整性的影响范围约为150~200m,影响形式为负指数型。     

协同多源遥感数据的北亚热带森林蓄积量贝叶斯分层估测

精确估算森林蓄积量是国家实现2060年前碳中和目标的迫切需求,而基于遥感的森林蓄积量定量反演是当前遥感应用领域面临的重要挑战和研究热点.光学遥感数据由于无法获取森林高度信息并存在信号饱和问题,反演森林蓄积量的精度较低,而机载Lidar数据能获取高度信息,但成本高、观测范围有限.本研究利用Sentinel-2多光谱、资源...     

Sigseg: a tool for the detection of position and velocity discontinuities in geodetic time-series

The detection of discontinuities in geodetic data is an ever more important topic due to both the influence of discontinuities on the results of models and analyses, and to the very meaning of discontinuities in physical phenomena. We consider and describe a mathematical model, originally formulated for the approximation of images by smooth functions, in one dimension (1D). The model had been designed to smooth the data while preserving and detecting its discontinuities following a variational approach. A second and more complex model for the approximation of images by functions with smooth first derivatives is also available. This second model had been designed to smooth the data while preserving and detecting the discontinuities of the data, but also those of the first derivative. Such interesting features suggest the chance to apply this second model to 1D geodetic data, in particular for the detection of discontinuities and velocity changes in position time-series rather than for signal smoothing. The sigseg (signal segmentation) program implements the two variational models in 1D and is presented with applications to geodetic data. The essential mathematical elements are sketched, and some details on the numerical implementation are given.     

Polarization state conformation and its application to change detection in polarimetric SAR data

For polarimetric SAR (POLSAR) images, it is ideal that scattering geometries of the same target should display resemblance between multidate images, which are used in change detection applications, since the scattering mechanisms may change due to the data acquisition geometry. However, sometimes it is difficult to achieve these conditions. An attempt is made to maximize the resemblance between the scattering geometries in multidate images for a specific target. An algorithm is developed based on the polarimetric basis transformation along with the polarization signatures. As a result, the resemblance between the scattering mechanisms of the same target in both images is maximized. The effects predicted by the theory are confirmed by the change detection analysis of POLSAR data acquired by the Jet Propulsion Laboratory Spaceborne Imaging Radar-C mission.     

国产尾标定位系统的研究及应用

对中国石油大学自主研发的全球卫星导航系统(GNSS)尾标定位系统的组成及运行原理进行了详细的阐述.介绍了该尾标定位系统在海洋拖缆作业中的应用,包括其核心软硬件的设计和主要工作流程.通过陆上模拟实验,对其电台传输距离和稳定性及定位精度进行测试,测试结果表明,尾标定位系统能够连续稳定地传输数据且能够实现厘米级的相对定位精度,可以满足实际生产中海上拖缆作业对导航定位的需求.     

量子粒子群BP神经网络在GNSS高程转换中的应用分析

提出了一种基于量子粒子群神经网络(QPSO-BP)模型的GNSS高程转换方法,通过建立GNSS点平面坐标与正常高之间的三层QPSO-BP数学模型而实现GNSS高程转换。试验分析结果表明,该方法全局迭代进化搜索能力高、稳健性强、拟合及预测精度高,在GNSS高程转换方面具有良好的有效性与先进性。     

预处理共轭梯度法解病态问题及在GPS中的应用

介绍测量数据处理中病态问题的岭估计思想及确定岭参数的方法。引入预处理共轭梯度法求解病态法方程组,说明算法的基本原理和它能有效减弱病态性的原因。用一个GPS差分动态定位的实例,通过与不同岭估计方法的对比分析,验证该方法是一个有效的数值迭代算法。     

Bayesian and Geostatistical Approaches to Combining Categorical Data Derived from Visual and Digital Processing of Remotely Sensed Images

This paper seeks a synthesis of Bayesian and geostatistical approaches to combining categorical data in the context of remote sensing classification. By experiment with aerial photographs and Landsat TM data, accuracy of spectral, spatial, and combined classification results was evaluated. It was confirmed that the incorporation of spatial information in spectral classification increases accuracy significantly. Secondly, through test with a 5-class and a 3-class classification schemes, it was revealed that setting a proper semantic framework for classification is fundamental to any endeavors of categorical mapping and the most important factor affecting accuracy. Lastly, this paper promotes non-parametric methods for both definition of class membership profiling based on band-specific histograms of image intensities and derivation of spatial probability via indicator kriging, a non-parametric geostatistical technique.     

Bayesian and geostatistical approaches to combining categorical data derived from visual and digital processing of remotely sensed images

This paper seeks a synthesis of Bayesian and geostatistical approaches to combining categorical data in the context of remote sensing classification. By experiment with aerial photographs and Landsat TM data, accuracy of spectral, spatial, and combined classification results was evaluated. It was confirmed that the incorporation of spatial information in spectral classification increases accuracy significantly. Secondly, through test with a 5-class and a 3-class classification schemes, it was revealed that setting a proper semantic framework for classification is fundamental to any endeavors of categorical mapping and the most important factor affecting accuracy. Lastly, this paper promotes non-parametric methods for both definition of class membership profiling based on band-specific histograms of image intensities and derivation of spatial probability via indicator kriging, a non-parametric geostatistical technique.     

贝叶斯原理在遥感影像恢复中的应用

总结了遥感影像数据获取、传输和存储过程中引起影像退化的原因。根据信号处理中的概率统计理论,推导出了一种可以不依赖目标成像模型的遥感影像去模糊算法。实验结果表明,该算法具有较强的影像恢复能力和抗噪能力,对于缺乏点扩散函数先验知识的模糊遥感影像更加适用。     

AR序列异常值探测的Bayes方法在卫星钟差预报中的应用

AR模型中若含有异常值,会使传统的建模、估计及检验方法陷人困境,从而不能准确地预测和控制。本文在无信息先验条件下,结合观测信息,计算了基于均值漂移模型和方差膨胀模型异常值事件发生的后验概率,提出了无信息先验下自回归模型中异常值探测的Bayes方法并对异常值进行了估算。该方法能将异常值准确地探测和估算出来,借此修正模型,可提高预测的准确性。最后,做了钟差实测数据计算,比较了模型修正前后预报的情况,验证了该方法的有效性。     

顾及有色噪声的卡尔曼滤波在多路径误差削弱中的应用

多路径误差为一时空环境效应,难以构建准确数学模型消除其影响,且该误差在基线两端不具有空间相关性,运用现有差分技术也无法很好消除,是高精度短基线测量中主要误差之一.为进一步削弱多路径误差,本文以监测站坐标时间序列中多路径误差为研究对象,根据多路径误差在历元间的时变特性,建立多路径误差状态空间模型,采用标准卡尔曼滤波和顾及有色噪声的卡尔曼滤波从监测站第一天双差固定解坐标残差序列中估计多路径误差改正序列,并根据多路径误差的周日重复特性,利用第一天得到的多路径误差改正序列对之后各天坐标序列进行改正.最后通过实验分析,得出顾及有色噪声的卡尔曼滤波估计方法优于标准卡尔曼滤波的结论.研究方法对提高GNSS定位精度具有重要实用价值.