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Assessment of GNSS zenith tropospheric delay responses to atmospheric variables derived from ERA5 data over Nigeria

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Satellite Navigation 2023年第1期4卷 167-182,I0005页

作者： Ifechukwu Ugochukwu Nzelibe Herbert Tata Timothy Oluwadare Idowu Department of surveying and geoinformatics Federal University of Technology AkureAkureNigeria

Tropospheric delay is a major error caused by atmospheric refraction in Global Navigation Satellite System(GNSS)*** study evaluates the potential of the European Centre for Medium-range Weather Forecast(ECMWF)Reanalysis 5(ERA5)atmospheric variables in estimating the Zenith Tropospheric Delay(ZTD).Linear regression models(LRM)are applied to estimate ZTD with the ERA5 atmospheric *** ZTD are also estimated using standard ZTD models based on ERA5 and Global Pressure and Temperature 3(GPT3)atmospheric *** ZTD estimates are evaluated using the data collected from the permanent GNSS continuously operating reference stations in the Nigerian *** results reveal that the Zenith Hydrostatic Delay(ZHD)from the LRM and the Saastamoinien model using ERA5 surface pressure are of identical accuracy,having a Root Mean Square(RMS)error of 2.3 mm while the GPT3-ZHD has an RMS of 3.4 *** the Zenith Wet Delay(ZWD)component,the best estimates are derived using ERA5 Precipitable Water Vapour(PWV).These include the ZWD derived by the LRM having an average RMS of 20.9 mm and Bevis equation having RMS of 21.1 mm and 21.0 mm for global and local weighted mean temperatures,*** evaluation of GPT3-ZWD estimates gives RMS of 45.8 *** study has provided a valuable insight into the application of ERA5 data for ZTD *** line with the fndings of the study,the ERA5 atmospheric variables are recommended for improving the accuracy in ZTD estimation,required for GNSS positioning.

关键词： ECMWF reanalysis 5(ERA5) Global navigation satellite systems(GNSS) Global pressure and temperature 3(GPT3) Modelling Nigeria Zenith tropospheric delay(ZTD)

A novel vehicle navigation map matching algorithm based on fuzzy logic and its application

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Journal of Central South University of Technology 2005年第2期12卷 214-219页

作者：童小华吴颂春吴淑琴刘大杰 Department of surveying and geoinformatics Tongji University Shanghai 200092 China

A new real-time map matching algorithm based on fuzzy logic is proposed. 3 main factors affecting the reliability of map matching, including the distance between the vehicle location and the matching road segment, the angle between the vehicle direction and the road segment direction and the road connectivity are discussed. Fuzzy rules for the distance, angle and connectivity are presented to calculate the matching reliability. 2 indicators for estimating the matching reliability are then derived, one is the lower limit of the reliability, and the other is the limit error of the difference between the maximal value and the second-maximal value of the reliability. A real-time map-matching system based on fuzzy logic is therefore developed. Using the real data of global positioning system(GIS) based navigation and geographic information system(GPS) based road map, the method is verified and the (results) prove the effectiveness of the proposed method.

关键词： map matching fuzzy logic reliability GPS GIS road network

Assessing the impacts of traffic calming at network level:A multimodal agent-based simulation

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Journal of Traffic and Transportation Engineering(English Edition) 2024年第1期11卷 41-54页

作者： Eftychia Zargiannaki Panagiotis G.Tzouras Eleni Antoniou Christos Karolemeas Konstantinos Kepaptsoglou School of Rural Surveying and Geoinformatics EngineeringNational Technical University of AthensZografou 15780Greece

The reduction of speed limits in urban roads through traffic calming schemes intends to ensure safer traffic conditions among road users by reducing the probability related to the occurrence of severe *** it from a different perspective,traffic calming measures can potentially resolve congestion problems at the same time by lowering the overall accessibility and attractiveness of private cars in urban *** study proposes a new methodological approach to explore and assess the direct impacts of traffic calming in the transport system efficiency of a metropolitan *** multi-agent transport simulation(MATSim)and Open-Berlin scenario are utilized to perform this simulation *** developing a new external tool,the free flow speed and road capacity of each network link is updated based on new speed limits and different compliance rates,which are defined per road hierarchy *** test scenarios that are formulated present radical conditions,where the speed limit in most urban roads of Berlin drops to 30 km/h or even 15 km/*** findings of this study show a considerably high increase in trips,passenger hours,and passenger kilometers using public transport modes,when traffic calming links are introduced,the reserve change is observed in private cars *** the speed limits are decreased in inner urban roads in most of the scenarios,the decrease of average travel speed of private cars is not so high as it was ***,private cars are used for longer distances in all test *** drivers seem to use already existed motorways and private road to *** simulations,driver compliance to the new speed limits seems to be a determinant factor that is strongly influenced by the design interventions applied in a traffic calming area.

关键词： Agent-based simulation Traffic calming Impact assessment Urban road network

STUDY ON SAMPLING INSPECTION SCHEME TO DIGITAL PRODUCTS IN GIS

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Geo-Spatial Information Science 2001年第1期4卷 62-67页

作者： liu chun Dept. of surveying and geoinformatics Tongji University Shanghai China

Adopting a principle of “check_accept for the first rank,inspection for the second rank”,this paper briefly discusses the rationale of the sampling inspection and the sampling inspection schemes to digital products in *** OC curve is drawn to explain the deficiency of the percent sampling ***,the method of One Time Limiting Quality of count selection is presented as the inspection scheme for production departments while the method of One Time After_inspection Mean Percent Defective Upper Limit of count selection is for acceptance departments.

关键词： sampling inspection digital products GIS

Understanding the multi-seasonal spectral and biophysical characteristics of reedbed habitats in the UK

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Geo-Spatial Information Science 2016年第4期19卷 233-244页

作者： Alex O.Onojeghuo George A.Blackburn Department of surveying and geoinformatics Nnamdi Azikiwe UniversityAwkaNigeria Lancaster Environment Centre Lancaster UniversityLancasterUK

Reedbed in the UK has been classified as priority habitat for most regional Biodiversity ***,critical information pertaining to the quality and spatial coverage of reedbed is currently *** paper presents the results of a project conducted in collaboration with the Cumbria Wildlife Trust and Environment Agency aimed at monitoring and understanding variations in the spectral reflectance and biophysical properties of reedbed canopies across Leighton Moss Nature Reserve in Lancashire,northwest *** the seasonal phenological cycle of the reedbed habitats in the study area,optimal spectral indices required for quantifying its biophysical properties were determined using field spectroscopy and ground-based *** of the experiment showed that the narrow-bandderived Difference Vegetation Index(DVI)and Renormalised Difference Vegetation Index(RDVI),with the correlation coefficient R2 of 0.77 and 0.72,respectively,provided the most accurate estimates of the leaf area index for the reedbed canopies.

关键词： Vegetation index leaf area index biophysical measures

Improved precise positioning with BDS-3 quad-frequency signals

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Satellite Navigation 2020年第1期1卷 328-337页

作者： Bofeng Li Zhiteng Zhang Weikai Miao Guang’e Chen college of surveying and geoinformatics Tongji UniversityShanghai 200092China Department of Geomatics Engineering University of CalgaryCalgary T2N 1N4Canada

The establishment of the BeiDou global navigation satellite system(BDS-3)has been completed,and the current constellation can independently provide positioning service ***-3 satellites provide quad-frequency signals,which can benefit the ambiguity resolution(AR)and high-precision *** paper discusses the benefits of quad-frequency observations,including the precision gain of multi-frequency high-precision positioning and the sophisticated choice of extra-wide-lane(EWL)or wide-lane(WL)combinations for instantaneous EWL/WL ***,the performance of EWL real-time kinematic(ERTK)positioning that only uses EWL/WL combinations is *** results indicate that the horizontal positioning errors of ERTK positioning using ionosphere-free(IF)EWL observations are approximately 0.5 m for the baseline of 27 km and 1 m for the baseline of 300 ***,the positioning errors are reduced to the centimetre level if the IF EWL observations are smoothed by narrow-lane observations for a short period.

关键词： Quad-frequency Precise point positioning Real-time kinematic Extra-wide-lane combinations Ambiguity resolution

Development of a multi-view and geo-event-driven real-time collaborative GIS

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International Journal of Digital Earth 2022年第1期15卷 134-147页

作者： Sun Yaqin Xu Chen Wu Jinxiong Yuan Hang Shi Haibo Zhan Xiumei Zhang Lin Key Laboratory of Land Environment and Disaster Monitoring MNR China University of Mining and TechnologyXuzhouPeople’s Republic of China college of surveying and geoinformatics Tongji UniversityShanghaiPeople’s Republic of China

Supporting distributed real-time collaborative work has become an important development trend in *** enables group users to cooperate and improve the use of scientific data and collaboration ***-time collaborative GIS(RCGIS)provides a platform for supporting synchronous collaboration using geospatial data in various *** RCGIS generally works on a single map view,which has the disadvantage of collaborative interface *** traditional system-driven mechanism of RCGIS is a computer-interaction event that has the disadvantage of an unfriendly collaborative *** paper presents a design and prototype of a RCGIS based on multi-view and geo-event driven *** geo-event-driven mechanism provides users with a smoother collaborative perception and interactions that are more natural and *** collaboration process for a GIS that is driven by geo-events is also discussed.A multi-view technique is used to make real-time GIS collaboration more *** paper also proposes a synchronization strategy for public–private ***,walk-through examples are used to demonstrate the use of RCGIS within a web environment.

关键词： Geographical information collaboration real-time multi-view geo-event driven

DEVELOPMENT OF A HYBRID MODEL FOR THREE-DIMENSIONAL GIS

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Geo-Spatial Information Science 2000年第2期3卷 6-12页

作者： SHI Wenzhong Department of Land surveying and geoinformatics The Hong Kong Polytechnic University Kowloon Hong Kong

This paper presents a hybrid model for three-dimensional Geographical Information Systems which is an integration of surface- and volume-based models. The Triangulated Irregular Network (TIN) and octree models are integrated in this hybrid models. The TIN model works as a surface-based model which mainly serves for surface presentation and visualization. On the other hand, the octree encoding supports volumetric analysis. The designed data structure brings a major advantage in the three-dimensional selective retrieval. This technique increases the efficiency of three-dimensional data operation.

关键词： hybrid three-dimensional model TIN model octree model GIS

DEVELOPMENT OF A GIS DATA MODEL WITH SPATIAL,TEMPORAL AND ATTRIBUTE COMPONENTS BASED ON OBJECT-ORIENTED APPROACH

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Geo-Spatial Information Science 2000年第1期3卷 17-23页

作者： SHI Wenzhong ZHANG Minwen Department of Land surveying and geoinformatics The Hong Kong Polytechnic University Kowioon Hong Kong

This paper presents a conceptual data model, the STA-model, for handling spatial, temporal and attribute aspects of objects in GIS. The model is developed on the basis of object-oriented modeling approach. This model includes two major parts: (a) modeling the signal objects by STA-object elements, and (b) modeling relationships between STA-objects. As an example, the STA-model is applied for modeling land cover change data with spatial, temporal and attribute components.

关键词： object-orientation GIS data modeling spatial, temporal and attribute model