NG Jun-min (The School of Automation S

cience and Electrical Engineering,Beihang University,Beijing 100083,China)As the var     

Wide-Area Augmentation System (WAAS) – The Metamorphosis of a Major FAA Program

The Federal Aviation Administration (FAA) is developing the wide-area augmentation system (WAAS) to supplement the Global Positioning System (GPS) and serve as a single en-route navigation aid. The program traveled a rocky road so far. We compare the original concept of WAAS with its current scaled down version, analyze the changed perspectives with respect to the utility of GPS for air navigation and the concomitant role of WAAS, and explore the future of GPS/WAAS. ? 2000 John Wiley & Sons, Inc.     

Application of Adaptive Kalman Filtering Algorithm in IMU/GPS Integrated Navigation System

The IMU(inertial measurement unit) error equations in the earth fixed coordinates are introduced firstly. A fading Kalman filtering is simply introduced and its shortcomings are analyzed, then an adaptive filtering is applied in IMU/GPS integrated navigation system, in which the adaptive factor is replaced by the fading factor. A practical example is given. The results prove that the adaptive filter combined with the fading factor is valid and reliable when applied in IMU/GPS integrated navigation system.     

Integrated Navigation Based on Robust Estimation Outputs of Multi-sensor Measurements and Adaptive Weights of Dynamic Model Information

IntroductionMulti-sensor combinationis a main tendencyinnavigation and positioning. The measurementsof the multi-sensors usually have different typesof systematic errors . The integrated navigationsystem can provide redundant information toweaken the influences of the systematic errorsand to detect the measurement outliers and thedisturbances of the kinematic model . As a re-sult ,the whole accuracy and reliability of navi-gation and positioning will be i mproved.In the application of multi-s…     

Integrity Monitoring of IGEX-98 Data – Part III: Broadcast Navigation Message Validation

At the Delft University of Technology (DUT), data of six stations participating in the first international GLONASS tracking campaign, IGEX-98, were analyzed with integrity monitoring software. The software was developed at the Department of Mathematical Geodesy and Positioning of DUT. The main function of the software is to detect slips and outliers in phase and code observations in real time. In addition, the software also allows the validation of the information contained in the broadcast navigation messages. The results of the IGEX-98 data analyses are presented in a three part series. In this third and final part of the series, GLONASS and GPS navigation message validation results will be discussed in detail. The first part was concerned with the availability of GLONASS observations (Jonkman & de Jong, 2000a), while in the second part, GLONASS slip and outlier statistics were considered (Jonkman & de Jong, 2000b). The discussion of the navigation message validation results concentrates on anomalies detected in the data of an IGEX-98 station in Switzerland. Data collected at this station from September 1998 to December 1999 was analyized. In all, 19 anomalies were detected by the integrity monitoring software, 8 in GLONASS messages and 11 in GPS messages. The cause of the anomalies was established by evaluating the original data files, studying official bulletins of the GLONASS and GPS ground segments, and in some cases tracing the anomaly through the complete IGEX-98 network. ? 2000 John Wiley & Sons, Inc.     

A Research on the Monitoring of Coastal Land use with Aerial Photographs in the Example of Kadırga bay (Çanakkale)

In coastal areas, environmental monitoring is an important tool in acquiring data to achieve the goal of sustainable usage relating to the character of changes in quantity and quality of land cover / land use. Studies can reveal the diversity of species and the natural factors and human influence affecting this diversity, occurring as a result of habitat fragmentation or destruction. As well as comparing the past and current state of environmental resources, monitoring helps to determine trends in the use and changes of resources. It was in this context that Kad?rga Bay, located on the northwest coast of Canakkale province, Turkey was studied. Also situated in this location is Assos, a significant site in ancient history with great tourism potential. This study determined changes in land cover / land use by means of photogrammetrical interpretation of data from 1957 to 2002. The research further aimed to determine pressure on the components of the ecological structure of the area. Based on the data obtained, projections can be made to protect the future, and will provide an important source for management of the area. Within the 45-year study period, it was determined that agriculture and secondary housing construction exerted the most pressure on the habitat of the area. In the main, an increase in agricultural activities and secondary house construction emerged as the cause of a decrease in wetlands and forest areas.     

The status of Earth Observation (EO) & Geo-Information Sciences in Africa – trends and challenges

ABSTRACT

Over the last 20 years, Africa has witnessed a slow but steady advancement in space-based technologies as they are increasingly recognized as an essential tool for decision-making that can leapfrog African development. A critical review on the outcome of a survey questionnaire focused on African private sector industries and universities, services and education/training in EO and Geo-Information Sciences, combined with literature review, and personal contacts reveal optimism for success in four sectors. These include the public sector (Government ministries and departments); Academic institutions (universities/colleges/national or regional centers); and space agencies and private sector companies. These sectors are intertwined and fundamental for creating an enabling environment for solutions to a broad spectrum of pressing priorities: job creation, poverty alleviation, and sustainable resource management. The result shows that there is an uptake in the number of institutions and market segments created. To date, there are more than 90 academic institutions and over 53 national space agencies in 28 countries. Within the 53 national space agencies, 11 African countries have already launched a total of 36 satellites into orbit, and additional five are expected by the first quarter of 2021; another five by 2025; thus, amounting to 46 satellites not foreseen ten years ago. In addition, there are now ten receiving and tracking stations in six African countries and 17 scientific National Associations or Societies with specialized expertise in Geo-Information technologies. The updated survey on the private sector in 2019 ascertained that around 4110 people are working in 130 of the 229 EO and Geo-Information Science companies identified in Africa. Ongoing investigations reiterate that companies dealing with space-based datasets and Geo-Information Sciences together with the private spin-off companies today absorb more than 15,000 people and the assumption is that this number is going to exceed 100,000 by the year 2025.     

The potential of Pléiades images with high angle of incidence for reconstructing the coastal cliff face in Normandy (France)

To monitor chalk cliff face along the Normandy coast (NW France) which is prone to erosion, we tested the potential of cliff face 3D reconstruction using pairs of images with high angle of incidence at different dates from the agile Pléiades satellites. The verticality aspect of the cliff face brings difficulties in the 3D reconstruction process. Furthermore, the studied area is challenging mainly because the cliff face is north-oriented (shadow). Pléiades images were acquired over several days (multi-date stereoscopic method) with requested incidence angles until 40°. 3D reconstructions of the cliff face were compared using two software: ASP® and ERDAS IMAGINE®. Our results are twofold. Firstly, despite ASP® provides denser point clouds than ERDAS IMAGINE® (an average of 1.60 points/m² from 40° incidence angle stereoscopic pairs on the whole cliff face of Varengeville-sur-Mer against 0.77 points/m² respectively), ERDAS IMAGINE® provides more reliable point clouds than ASP® (precision assessment on the Varengeville-sur-Mer cliff face of 0.31 m ± 2.53 and 0.39 m ± 4.24 respectively), with a better spatial distribution over the cliff face and a better representation of the cliff face shape. Secondly, the quality of 3D reconstructions depends mostly on the amount of noise from raw images and on the shadow intensity on the cliff face (radiometric quality of images).     

《德国大地测量杂志》(Journal of Geodesy)2003,77(1-2)要目

R .Daeh,G.Beutler,U.Hugentobler,S.Sehaer,T.Sehildkneeht,T.Springer,G.Dudle,IJ.ProstTime transfer using GPS earrier phase:error propagation and results利用GPS载波相位传递时间的误差传播及其结果M .King,R.Colemar,IJ.N.Nguyen:SPurious periodie horizontal signals in sub一daily GPS Position estimates亚周日GPs位置估算中的伪周期性水平信号A .IJannes,S.Dur:Dual algebraie formulation of differential GPS差分GPS的双代数公式J .Klokoenik,J .Kosteleeky,R.H.Gooding:On fine orbit seleetion …     

The nature and possible causes of land cover change (1984 –1996) along a rainfall gradient in southeastern Botswana

Land cover change analysis was undertaken in semi-arid southeastern Botswana. The aim was to determine how remotely sensed data could be applied over time and under different rainfall regimes to help assess the relative significance of biophysical and human factors in causing land cover change in a rapidly evolving developing world context. To this purpose, land cover changes were studied along an east (hardveld)-west (sandveld) gradient of decreasing rainfall and decreasing population density. Three years of Thematic Mapper imagery from 1984, 1994 and 1996, covering the period from the 1980s drought to the 1990s ‘normal’ rainfall regime were analysed using supervised classification techniques. Land cover change analysis revealed that over a large part of the study area the dry and more biophysically vulnerable western sandveld showed greater vegetation recovery than the eastern hardveld with its more productive soils and higher rainfall. Underlying causes behind this apparent reversal of trends are inferred to be mainly socioeconomic in nature and particularly related to higher population density due to the rise of salaried urban occupation opportunities in the hardveld. This work concludes that, while biophysical causes of change are important, the human dimension is regarded as being more significant especially where human factors negate otherwise positive biophysical effects in an agrarian developing country.     

King George Island GIS (KGIS) project of WGGGI —A state of the art

The presentation contains information on existing geodetic data for King George Island obtained from the questionnaires distributed among the members of the WGGGI.     

全球定位系统(GPS)的最新进展(上)

首先分析了 GPS观测的主要误差源。其次 ,叙述了空基 (星载 ) GPS的科学应用 ,其中 TOPEX和 Micro L abe任务都是成功的范例。关于 GPS对于气象学的应用 (GPS/MET)方面 ,比较详细地介绍了地基 GPS/MET和空基(星载 ) GPS/MET的最新进展 ,二者处于 GPS的最新进展的前沿。     

全球定位系统(GPS)的最新进展(下)

3　动态 GPS定位自从利用 GPS载波相位观测的机载动态定位于 1 985年第一次得到证实之后 ,可靠的 GPS解支持航空摄影测量、遥感活动和地球物理测量的能力显著改进了。这些改进来源于若干因素的综合 :第一 ,运动 GPS接收机可以跟踪 8颗或更多颗卫星 ;第二 ,可以得到精密星历供后处理之用 ;第三 ,提出了一些算法 ,它们能以少量的相位和伪距观测量在运动中初置相位偏差。这些因素综合起来 ,产生了精确到厘米级的动态定位能力。这就是动态 GPS定位技术。它可以把距离延伸到约 1 0 0 km。采用 KARS( Kine-matic And Rapid Static)程序…     

The long-wave infrared (8-12 μm) spectral features of selected rare earth element—Bearing carbonate,phosphate and silicate minerals

Rare earth elements (REEs) are a group of metals essential to high technology industries. This high demand, combined with a high supply risk, has led to an understanding that REEs are critical to society. Despite the potential that hyperspectral imaging (HSI) data offers for a fast and non-invasive characterization of the REEs, it is still poorly understood whether REEs have some information in the long-wave infrared (LWIR; 8–12 μm) wavelength range that can be used for their identification. To partially fill this gap, we have investigated the spectroscopy of twelve REE-bearing mineral samples using relatively high spatial and spectral resolution LWIR hyperspectral imaging data. These samples were formerly characterized using electron probe microanalysis (EPMA), scanning electron microscopy (SEM), and hyperspectral imaging data acquired in the 0.4–2.5 μm wavelength range. Results from these analyses were compared to and used to guide the analysis of the HSI data recorded in the LWIR range. This information was further compared to a reference spectral library of rare earth oxides. Our findings suggest that the spectral features of the samples can generally be traced to the asymmetric degenerate stretching and bending modes of the X-O (X = C, Si, P) groups. Moreover and contrary to what has been observed in the shorter wavelengths, there are no definitive spectral features in the LWIR wavelength region that could be assigned to any specific REE.