基于多技术全球参考框架的维持及应用分析     

成英燕  王虎  许长辉  张永浩  刑云剑 《测绘科学》2019,44(6):37-46

全球基准从参与构建框架的方式来说分为长期框架和短期框架(历元框架),由于框架点运动的非线性特性,长期框架构建的基准无法描述毫米级地球表面运动,常会采用短期框架来描述。短期框架实现时严格说应该保证空基(卫星轨道)和地基(ITRF、IGS)的一致性,再者,空间大地测量技术综合框架与单一技术基准在构建和维持上同样存在差异,这些不一致都将导致地面站坐标表达的差异。不同时期长期框架维持差异性及精度也是我国框架维持需考虑的问题,该文就以上各类框架构建策略不同对实际点位的影响进行了比较分析并给出结论,供我国高精度基准建设参考。  相似文献   

A Kalman Filter Approach to Realize the Lowest Astronomical Tide Surface     

D. C. Slobbe  J. Sumihar  T. Frederikse  M. Verlaan  R. Klees  F. Zijl 《Marine Geodesy》2018,41(1):44-67

In this paper , we present a novel Kalman filter approach to combine a hydrodynamic model-derived lowest astronomical tide (LAT) surface with tide gauge record-derived LAT values. In the approach, tidal water levels are assimilated into the model. As such, the combination is guided by the model physics. When validating the obtained “Kalman-filtered LAT realization” at all tide gauges, we obtained an overall root-mean-square (RMS) difference of 15.1 cm. At the tide gauges not used in the data assimilation, the RMS is 17.9 cm. We found that the assimilation reduces the overall RMS difference by ～ 31% and ～ 22%, respectively. In the Dutch North Sea and Wadden Sea, the RMS differences are 6.6 and 14.8 cm (all tide gauges), respectively. Furthermore, we address the problem of LAT realization in intertidal waters where LAT is not defined. We propose to replace LAT by pseudo-LAT, which we suggest to realize similarly as LAT except that all water level boundary conditions and assimilated tidal water levels have to be enlarged by a constant value that is removed afterward. Using this approach, we obtained a smooth reference surface for the Dutch Wadden Sea that fits LAT at the North Sea boundary within a few centimeters.  相似文献   

Recommending attractive thematic regions by semantic community detection with multi-sourced VGI data     

Zhewei Liu  Xiaolin Zhou  Anshu Zhang 《International journal of geographical information science》2019,33(8):1520-1544

Attractive regions can be detected and recommended by investigating users’ online footprints. However, social media data suffers from short noisy text and lack of a-priori knowledge, impeding the usefulness of traditional semantic modelling methods. Another challenge is the need for an effective strategy for the selection/recommendation of candidate regions. To address these challenges, we propose a comprehensive workflow which combines semantic and location information of social media data to recommend thematic urban regions to users with specific interests. This workflow is novel in: (1) developing a data-driven geographic topic modelling method which utilizes the co-occurrence patterns of self-explanatory semantic information to detect semantic communities; (2) proposing a new recommendation strategy with the consideration of region’s spatial scale. The workflow was implemented using a real-world dataset and evaluation conducted at three different levels: semantic representativeness, topic identification and recommendation desirability. The evaluation showed that the semantic communities detected were internally consistent and externally differentiable and that the recommended regions had a high degree of desirability. The work has demonstrated the effectiveness of self-explanatory semantic information for geographic topic modelling and highlighted the importance of including region spatial scale into the model for an effective region recommending strategy.  相似文献   

Commercial GIS location analytics: capabilities and performance     

Alan T. Murray  Jing Xu  Zifan Wang  Richard L. Church 《International journal of geographical information science》2019,33(5):1106-1130

An essential location analytic method is GIS, able to support map-based display along with geographic data creation, management, manipulation in addition to functions for suitability evaluation. Location models have proven to be critical as well, with many prominent approaches found in popular GIS software. This paper reviews a class of location models and provides an overview of the methods used to solve these models. This is significant because of the broad use and application of location models in GIS to address important problems and issues facing society. Spatial analytical insights are essential. The implications of models and methods available through GIS are explored, particularly notions of solution quality. Case studies are offered to highlight ease of access to location models in GIS along with observed computational performance.  相似文献   

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陈俊勇 《大地测量与地球动力学》2008,28(4):1-6

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欧同庚  王琪  傅辉清  路杰  陈志高  杨博雄 《大地测量与地球动力学》2008,28(5):129-132

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陆珏  陈义  郑波 《大地测量与地球动力学》2008,28(5):77-81

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车步单元地质特征及时代初探     

吴旭玲  欧阳克贵 《华东地质学院学报》2000,23(2):121-123

车步单元为基性侵入体,同于钛铁矿含量较高,发现有多处矿点,与成密切相关,在岩石化学特征及成岩时代上与区域菖蒲组玄武岩有同期同源性,定位时代为早侏罗世。  相似文献   

探地雷达在大口径基桩无损检测中的应用   总被引：3，自引：0，他引：3  

李梁  兰樟松  张炎孙 《物探与化探》2000,24(6):474-476

介绍了雷达工作原理、检测方法技术。以樟树市某区ZH 11A基桩检测为例,分析了大口径桩的雷达波组特征与桩体结构之间的关系,为探地雷达无损检测大口径桩提供了依据。  相似文献   

Invariant geodynamical information in geometric geodetic measurements     

Peiliang Xu  Seiichi Shimada  Yoichiro Fujii  & Torao Tanaka 《Geophysical Journal International》2000,142(2):586-602

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