测绘专业认证背景下的“GNSS测量原理与应用”课程教学研究

工程教育专业认证是一种合格评估,不同于院校本科评估和审核评估,通过意味着专业全体学生达到毕业要求。目前全国高校的许多专业正接受工程教育专业认证,测绘专业工程教育专业认证也不例外。在此背景下,本文首先回顾了当前全国专业认证的现状,然后阐述了工程教育认证下的测绘专业课程体系建设,着重分析了测绘专业教育成果导向教学设计流程,讨论了“GNSS测量原理与应用”课程教学大纲的修改与完善,最后研究了在课程课堂教学中如何体现工程教育专业认证的核心理念,且举例进行了论述。     

The Role of GNSS Vertical Velocities to Correct Estimates of Sea Level Rise from Tide Gauge Measurements in Greece

In this study, we show how the Global Navigation Satellite System (GNSS)-derived vertical velocities contribute to the correction of tide gauge (TG) measurements used for the sea level rise estimation in Greece. Twelve sites with records of local sea level heights are processed in order to estimate their trend. Certain error sources related to TGs, e.g. equipment changes, data noise, may lead to biased or erroneous estimations of the sea level height. Therefore, it would be preferred to follow a robust estimation technique in order to detect and reduce outlier effects. The geocentric sea level rise is estimated by taking into account the land vertical motion of co-located GNSS permanent stations at the Hellenic area. TGs measure the height of the water relative to a monitored geodetic benchmark on land. On the other hand, using GNSS-based methods the vertical land motion can be derived. By means of extended models fitted to the GNSS time-series position, obtained from seven years of continuous data analysis, periodic signals are well described. The synergy of the two co-located techniques results in the correction of TG relative sea level heights taking into account the GNSS vertical velocities and consequently obtaining the conversion to absolute (geocentric) sea level trend.     

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基于GNSS网络的实时精密单点定位及精度分析

基于局域GNSS网络,以历元间、星间差分技术实时估计了GPS卫星相对钟差的历元间差值;针对所估计实时精密钟差的特征,推导了实时精密单点定位的估计模型.对所估计得到的相对钟差的历元间差值、实时定位结果分别进行了比较、分析.结果表明,相对钟差的历元间差值与IGS的最终星历相比其精度可以达到0.08 ns;每小时观测的实时静态定位结果在N、E、U三个方向的精度分别为1.47、3.62、4.09 cm.动态模式,实时结果在N、E、U三个方向的精度分别为2.63、3.82、5.20 cm.与采用IGS最终轨道和钟差解算的结果相比较,实时计算结果优于采用精密轨道和精密钟差计算结果.     

GNSS流动观测水平速度精度评估

利用GNSS连续观测数据评估了GNSS流动观测水平速度精度,并分析了相邻两期观测时间差、每期观测时长、观测周期对水平速度精度的影响。结果表明：按照目前的观测模式,流动观测与连续观测得到的水平速度值之差的绝对值在3 mm/a以内;相邻两期观测时间不一致会影响流动观测水平速度的精度,如果绝对值在3 mm/a以内的速度差为可接受值,那么建议相邻两期观测时期差应控制在25天之内;延长每期观测时间和缩短观测周期能提高流动观测水平速度精度。     

GNSS伪距随机模型估计的非差组合方法

基于非差观测值和无一阶电离层误差、无几何距离的组合准则导出2个UGIF组合,进而提出GNSS[JP2]非差伪距随机模型估计的UGIF非差组合方法。该方法仅需单站、单颗卫星的UGIF组合,适用于高低频情况下的非差伪距随机模型的实时或事后估计。利用中国矿业大学单基站连续运行站双模双频数据,验证方法的正确性与有效性。     

精密单点定位在GNSS区域网监测中的应用

基于精密单点定位软件PANDA,对陆态网络海南区域网2009、2011、2013年连续3期GNSS观测数据进行处理,得到各点在ITRF2008下的坐标;对各期结果进行分析,得出海南区域网的平均变化速度E方向为32.16 mm/a,N方向为-10.08 mm/a。结果表明,基于精密单点定位方法,可获得与基线解基本一致的速度信息。     

基于三峡秭归井水位和GNSS观测特征的地震活动性研究

三峡水库蓄水后,秭归盆地内部仙女山断裂北端邻近区域内发生多次3.5级以上地震,该地区的地震活动备受关注。本研究分析了该区域秭归井动水位的变化、水化学特征以及同期GNSS形变数据,结果显示:①秭归井水位的快速变化主要受该区域构造应力变化的影响,前期以拉张应力为主,后期区域应力变为挤压状态;②GNSS应变场特征显示面膨胀率高值区位于三峡库区周边及其南部,极高值区恰好位于仙女山断裂北部,且GNSS时间序列与秭归井水位的涨落存在较好的同步性;③2020年10月初开始的震群与该地区持续6个月的挤压状态有关,表明研究区应力积累已经超过岩层抗剪强度,岩层发生破裂。     

Upper crustal deformation characteristics in the northeastern Tibetan Plateau and its adjacent areas revealed by GNSS and anisotropy data

The northeastern part of the Tibetan Plateau is a region where different tectonic blocks collide and intersect, and large earthquakes are frequent. Global Navigation Satellite System(GNSS) observations show that tectonic deformation in this region is strong and manifests as non-uniform deformation associated with tectonic features. S-wave splitting studies of near-field seismic data show that seismic anisotropy parameters can also reveal the upper crustal medium deformation beneath the reporting...