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1.
为了评定斜拉桥环境下GPS/BDS组合定位的能力,以苏通大桥桥面监测为例,对BDS、GPS、GPS/BDS的定位精度进行了试验分析。分析比较了系统组合前后的可见卫星数的变化、不同卫星截止高度角下的卫星可见数以及组合前后几何精度因子的变化。结果表明,组合定位有效增加了可见卫星数,大大降低了位置精度因子,尤其当观测环境存在较大多路径误差时,通过提高卫星高度截止角,GPS和BDS组合定位可以有效克服多路径效应,提高定位精度。实际监测数据的解算表明,组合定位相对于单系统定位精度上有明显提高,监测结果可以反映桥梁重要部位的变形特征,满足桥梁监测的需要。试验结果对类似工程具有较好的参考价值。 相似文献
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本文对组合GNSS系统进行静态相对定位测量与RTK测量试验,研究结果表明:在静态相对定位测量中,BDS的数据利用率、多路径效应误差优于GPS与GLONASS,BDS的定位精度优于GLONASS略低于GPS;组合系统中GPS/BDS与GPS/BDS/GLONASS的定位精度较优,引入GLONASS对定位精度改善的作用不明显。在RTK测量中,当观测条件理想时,GPS/BDS较GPS可见卫星数目多,PDOP值低,中误差小。当观测条件较差时,GPS/BDS较GPS可见卫星数目多,PDOP平均值低,中误差小,限差内固定解获得时间减少76.1%;GPS/BDS/GLONASS较GPS/BDS在中误差、水平精度和垂直精度上更优,限差内固定解获得时间更稳定可靠。 相似文献
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单一卫星系统单频RTK定位可靠性较低,难以满足实时定位需求。由于GPS,BDS及GALILEO均采用CDMA技术体制,GPS/BDS/GALILEO多模系统耦合度较高,可有效应用于RTK动态定位。采用实测数据进行GNSS单频单历元RTK计算,实验结果表明:多模GNSS系统其模糊度ADOP值较小,模糊度固定成功率较高更适用于RTK定位领域。截止高度角较高时多模系统优势更加明显。 相似文献
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BDS/GPS组合单历元相对定位性能分析 总被引：1，自引：0，他引：1
《现代测绘》2017,(4)
阐述了BDS/GPS组合单历元解算数学模型的相关理论,并进行了相应的公式推导;通过BDS、GPS单系统以及组合系统从不同基线长度、不同截止高度角等方面分析动态解算性能。实验结果表明:(1)在江苏地区,BDS系统可提供单历元至少8颗卫星,从可见卫星数量和可观测时长角度来看,BDS对BDS/GPS导航定位具有重要的贡献;(2)组合BDS/GPS系统单频RTK相比GPS RTK在截止高度角较高的情况下仍可以单历元固定模糊度,且模糊度的固定率和成功率超过90%;(3)对于6km以下的短基线,组合系统定位精度优于单系统,其在平面方向优于1cm,高程方向优于3cm。 相似文献
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基于DREAMNET的GPS/BDS/GLONASS多系统网络RTK定位性能分析 总被引：1，自引：1，他引：0
随着BDS系统完成亚太地区组网、GLONASS系统再次实现满星座部署以及GPS系统的现代化,多系统集成已逐步成为网络RTK技术的发展趋势。本文结合笔者所在课题组自主研发的网络RTK数据处理系统DREAMNET,对不同卫星系统组合模式下的定位精度进行比较分析。试验结果表明,GPS/BDS/GLONASS网络RTK和GPS/BDS网络RTK的定位精度最高,GPS、BDS单系统网络RTK次之。此外,随着高度角的增加,GPS单系统网络RTK的可用性显著降低,而GPS/BDS/GLONASS网络RTK在高度角为40°时依然可以在99.84%的时间里提供水平精度0.01 m、高程精度0.025 m的定位服务。最后,对15 d的定位结果进行统计,包括不依赖GPS系统的BDS和BDS/GLONASS在内的6种组合方式皆可达到水平0.01 m、高程0.025 m的定位精度,其中GPS/BDS/GLONASS网络RTK则可以得到水平0.006 m、高程0.015 m的定位精度,证明DREAMNET的定位精度和稳定性完全可以满足测绘作业的需要。 相似文献
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针对GLONASS采用频分多址技术导致双差观测方程中双差模糊度失去整周特性的问题，提出了一种基于站间单差模糊度分别求解的方法，并结合附加模糊度参数的卡尔曼滤波模型，实现了GPS/BDS/GLONASS组合RTK定位。通过自编RTK程序对GPS、BDS与GLONASS双频实测短基线数据进行测试，并对比分析其他RTK模式下的稳定性与定位精度。结果表明，GLONASS单频和双频定位的模糊度固定率分别为99.8%、99.7%，其定位精度与BDS、GPS相差不大。在单频或双频RTK定位中，双系统、三系统组合定位的稳定性和定位精度明显高于单系统，其中三系统组合定位的稳定性最好，精度最高。随着频率增加，初始化时间明显减少，为实现单历元获得固定解提供了可能性。 相似文献
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针对单系统卫星定位中存在的多种问题,详细阐述了BDS/GPS组合定位原理,在统一时空基准条件下,通过算法实现BDS与GPS数据融合,对实测数据处理,分析BDS/GPS组合相对定位的定位精度。结果表明,BDS/GPS组合相对定位能够有效增加空间可视卫星数、改善了PDOP值。在中长基线下,BDS定位精度与GPS相当;长基线下,组合定位精度优于单系统,且稳定性较好。 相似文献
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针对在不同截止卫星高度角时,GPS,BDS,GPS/BDS系统间伪距差分定位精度的差异,文中对多系统融合伪距差分定位的数学模型方法进行研究。以香港CORS站6.9km和34.0km的两条基线为例,在截止卫星高度角10°、20°、30°、40°的情况下,进行GPS,BDS,GPS/BDS伪距差分基线解算。结果表明,与34.0km基线相比,6.9km基线伪距差分定位具有更高的精度,在不同截止高度角下,GPS/BDS组合系统在E,N,U方向的定位精度都优于单GPS,BDS系统,且定位结果更加稳定,特别在截止高度角为40°的极端条件下,GPS/BDS组合伪距差分定位精度仍能达到m级左右。 相似文献
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采用Landsat TM数据分析了阿克苏河—塔里木河断面水质污染状况,通过波段的DN值和常规监测数据建立能反映水质状况的
污染物监测模型。结果发现,将2000年常规监测数据代入模型后,与遥感数据的结果基本吻合| 重建阿克苏河—塔里木河的连续水体
污染变化曲线,得出污染物浓度随着远离上游而增加。 相似文献
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Monitoring drought dynamics in the Aravalli region (India) using different indices based on ground and remote sensing data 总被引：5，自引：0，他引：5
C. Bhuiyan R.P. Singh F.N. Kogan 《International Journal of Applied Earth Observation and Geoinformation》2006,8(4):289-302
The hard-rock hilly Aravalli terrain of Rajasthan province of India suffers with frequent drought due to poor and delayed monsoon, abnormally high summer-temperature and insufficient water resources. In the present study, detailed analysis of meteorological and hydrological data of the Aravalli region has been carried out for the years 1984–2003. Standardised Precipitation Index (SPI) has been used to quantify the precipitation deficit. Standardised Water-Level Index (SWI) has been developed to assess ground-water recharge-deficit. Vegetative drought indices like Vegetation Condition Index (VCI) and Temperature Condition Index (TCI) and Vegetation Health Index (VHI) have been computed using NDVI values obtained from Global Vegetation Index (GVI) and thermal channel data of NOAA AVHRR satellite. Detailed analyses of spatial and temporal drought dynamics during monsoon and non-monsoon seasons have been carried out through drought index maps generated in Geographic Information Systems (GIS) environment. Analysis and interpretation of these maps reveal that negative SPI anomalies not always correspond to drought. In the Aravalli region, aquifer-stress shifts its position time to time, and in certain pockets it is more frequent. In comparison to hydrological stress, vegetative stress in the Aravalli region is found to be slower to begin but quicker to withdraw. 相似文献
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Piyoosh Rautela Ramesh Chandra Lakhera 《International Journal of Applied Earth Observation and Geoinformation》2000,2(3-4)
The area around Sataun in the Sirmur district of Himachal Pradesh, India (falling between the rivers Giri and Tons; both tributaries of the Yamuna River) was studied for landslide vulnerability on behalf of the inhabitants. The study was made using extensive remote sensing data (satellite and airborne). It is well supported by field evidence, demographic and infrastructural details and aided by Geographic Information System (GIS) based techniques. Field observations testify that slope, aspect, geology, tectonic planes, drainage, and land use all influence landslides in the region. These parameters were taken into consideration using the statistical approach of landslide hazard zonation. Using the census data of 1991, vulnerability of the populace to the landslide hazard was accessed. As most of the infrastructure in the region is concentrated around population centres, population data alone was used for vulnerability studies. 相似文献
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ZHAN F. Benjamin 《地球空间信息科学学报》2011,(1)
Although it is well known that coseismic gravity changes take place during an earthquake, previous research has not yielded convincing evidence demonstrating that significant gravity changes occur before large earthquakes. Furthermore, even if we suspect that gravity changes occur before large earthquakes, we have yet to demonstrate how to consistently observe these changes for useful earthquake forecast that would bring benefits to society. We analyzed ground gravity survey data obtained in 1998, 2000, 200... 相似文献
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GNSS系统及其技术的发展研究 总被引：3，自引：1，他引：2
阐述了国际上卫星导航系统的总体发展,对美、俄、欧、中的四大全球系统,以及相关的区域系统和增强系统进行了简单的介绍,研究分析了GNSS系统及其技术的发展趋势,同时分析了我国Compass全球系统面临的机遇和挑战,并提出了我国未来工作的建议. 相似文献
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“4D”技术及其应用 总被引：13，自引：0，他引：13
介绍“４Ｄ”（即数字地面模型、数字正射影像、数字栅格地图和数字线划地图）系列产品的生产流程、关键技术、及其在耕地保护、防灾减灾救灾和城市规划等方面的应用方法。 相似文献
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《International Journal of Digital Earth》2013,6(1):66-87
Abstract Virtual Australia is not a well-defined or agreed concept. This discussion paper conceptualises Virtual Australia as a ‘virtual [digital] model containing and representing all non-trivial objects and their contextual environment – from blue sky to bedrock – in real world Australia’. It describes a scenario for Virtual Australia, one or two decades from now, in which the locations and conditions of non-trivial objects and their environment are updated automatically through a combination of remote sensing and wireless communication technologies in support of a ‘Supranet’. It then examines the concept of the ‘Supranet’ – a pervasive information network based largely on wireless technology linking the physical world to a virtual model in real time – and develops and discusses three principal characteristics of the Supranet: the ability to have or collect specific information (know); the ability to process information (think); and the ability to communicate that information. If, in the near future, any or all non-trivial devices are to some extent able to know, think and communicate, the potential for object autonomy will be realised. 相似文献
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Toward seamless indoor-outdoor applications: Developing stakeholder-oriented location-based services
Kohei OGAWA Edward VERBREE Sisi ZLATANOVA Naohiko KOHTAKE Yoshiaki OHKAMI 《地球空间信息科学学报》2011,14(2):109-118
Location-Based Services (LBS),an emerging new business based on smartphone and mobile networks,are becoming more and more popular.Most of these LBSs,however,only offer non-seamless indoor/outdoor applications and simple applications without giving stakeholders the chance to play an active role.Our specific aim is to solve these issues.This paper presents concepts to solve these issues by expanding the Open Location Services Interface Standard (OpenLS) to allow seamless indoor/outdoor positioning and to extend the content of the services to include information recommended by stakeholders. 相似文献
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地理数据库的关系模型及其实现 总被引：1，自引：0，他引：1
本文从以图论观点分析地理实体入手,系统阐述了地理数据库关系模型的设计法和过程。作者于1984年4～9月间在微型机上设计建立了关系型地理数据库的实方验系统(RGDB)。该系统采用了本文提出的关系模型,采用了可动态扩库的子库组合结构,这种结构具有灵活性和提高空间利用率的优点。RGDB含有多种功能的数据操作命令,除了具有一般检索功能外,还能进行“开窗”选取和十分“自由”的映象选取。本文对RGDB系统的主要性能和实现途径作了扼要介绍。 相似文献