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Evaluation of strategies for the ultra-rapid orbit prediction of BDS GEO satellites / Wenxi Zhao in Geo-spatial Information Science, vol 26 n° 1 (March 2023)  

Public [article]  inGeo-spatial Information Science > vol 26 n° 1 (March 2023) . - pp 16 - 30 Titre : Evaluation of strategies for the ultra-rapid orbit prediction of BDS GEO satellites Type de document : Article/Communication Auteurs : Wenxi Zhao, Auteur ; Xiaolei Dai, Auteur ; Yidong Lou, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : pp 16 - 30 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Techniques orbitales [Termes IGN] constellation BeiDou [Termes IGN] éclipse solaire [Termes IGN] orbite géostationnaire [Termes IGN] orbitographie [Termes IGN] rayonnement solaire Résumé : (auteur) The quality of BeiDou Navigation Satellite System (BDS) Geostationary Earth Orbit (GEO) ultra-rapid products is unsatisfactory because GEO satellites are nearly stationary relative to ground stations. To optimize the quality of these ultra-rapid orbit products, we investigated the effects of the fitting arc length, an a priori Solar-Radiation Pressure (SRP) model, and the along-track empirical acceleration on the prediction of BDS GEO satellite orbits. The predicted orbit arcs of 24-h were evaluated through comparisons with the corresponding observed orbit arc and Satellite Laser Ranging (SLR) observations. In both eclipse and non-eclipse seasons, accuracy of the orbit predictions obtained using a 48-h fitting arc length were better than those obtained using 24-h and 72-h fitting arc lengths. Although the overlapping precision of predicted orbits exhibited no obvious improvement when an a priori SRP model was employed, the systematic bias in the SLR residuals was significantly reduced. Specifically, the mean value of SLR residuals decreased from −0.248 m to −0.024 m during non-eclipse seasons and from −0.333 m to −0.041 m during eclipse seasons, respectively. In addition, when an empirical acceleration in the along-track direction was introduced, the three-Dimensional Root-Mean-Square (3D RMS) of overlapping orbits during eclipse seasons decreased from 2.964 to 1.080 m, which is comparable to that during non-eclipse seasons. Furthermore, the Standard Deviation (STD) of SLR residuals decreased from 0.419 to 0.221 m during eclipse seasons. The analysis of SRP estimates shows that the stability of SRP parameters was significantly enhanced after the introduction of along-track empirical acceleration in eclipse seasons. The optimal BDS GEO ultra-rapid orbit prediction products were yielded by using a 48-h fitting arc length, an a priori SRP model and an along-track empirical acceleration. Numéro de notice : A2023-182 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/10095020.2022.2071177 En ligne : https://doi.org/10.1080/10095020.2022.2071177 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102968 [article]

Understanding collective human movement dynamics during large-scale events using big geosocial data analytics / Junchuan Fan in Computers, Environment and Urban Systems, vol 87 (May 2021)  

Public [article]  inComputers, Environment and Urban Systems > vol 87 (May 2021) . - n° 101605 Titre : Understanding collective human movement dynamics during large-scale events using big geosocial data analytics Type de document : Article/Communication Auteurs : Junchuan Fan, Auteur ; Kathleen Stewart, Auteur Année de publication : 2021 Article en page(s) : n° 101605 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale [Termes IGN] collecte de données [Termes IGN] données GPS [Termes IGN] données issues des réseaux sociaux [Termes IGN] données localisées des bénévoles [Termes IGN] données massives [Termes IGN] dynamique spatiale [Termes IGN] échantillonnage de données [Termes IGN] éclipse solaire [Termes IGN] estimation par noyau [Termes IGN] Etats-Unis [Termes IGN] événement [Termes IGN] géolocalisation [Termes IGN] migration humaine [Termes IGN] mobilité territoriale [Termes IGN] téléphonie mobile Résumé : (auteur) Conventional approaches for modeling human mobility pattern often focus on human activity and movement dynamics in their regular daily lives and cannot capture changes in human movement dynamics in response to large-scale events. With the rapid advancement of information and communication technologies, many researchers have adopted alternative data sources (e.g., cell phone records, GPS trajectory data) from private data vendors to study human movement dynamics in response to large-scale natural or societal events. Big geosocial data such as georeferenced tweets are publicly available and dynamically evolving as real-world events are happening, making it more likely to capture the real-time sentiments and responses of populations. However, precisely-geolocated geosocial data is scarce and biased toward urban population centers. In this research, we developed a big geosocial data analytical framework for extracting human movement dynamics in response to large-scale events from publicly available georeferenced tweets. The framework includes a two-stage data collection module that collects data in a more targeted fashion in order to mitigate the data scarcity issue of georeferenced tweets; in addition, a variable bandwidth kernel density estimation(VB-KDE) approach was adopted to fuse georeference information at different spatial scales, further augmenting the signals of human movement dynamics contained in georeferenced tweets. To correct for the sampling bias of georeferenced tweets, we adjusted the number of tweets for different spatial units (e.g., county, state) by population. To demonstrate the performance of the proposed analytic framework, we chose an astronomical event that occurred nationwide across the United States, i.e., the 2017 Great American Eclipse, as an example event and studied the human movement dynamics in response to this event. However, this analytic framework can easily be applied to other types of large-scale events such as hurricanes or earthquakes. Numéro de notice : A2021-275 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/SOCIETE NUMERIQUE Nature : Article DOI : 10.1016/j.compenvurbsys.2021.101605 Date de publication en ligne : 05/02/2021 En ligne : https://doi.org/10.1016/j.compenvurbsys.2021.101605 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97358 [article]

Reducing the draconitic errors in GNSS geodetic products / C.J. Rodriguez-Solano in Journal of geodesy, vol 88 n° 6 (June 2014)  

Public [article]  inJournal of geodesy > vol 88 n° 6 (June 2014) . - pp 559 - 574 Titre : Reducing the draconitic errors in GNSS geodetic products Type de document : Article/Communication Auteurs : C.J. Rodriguez-Solano, Auteur ; Urs Hugentobler, Auteur ; et al., Auteur Année de publication : 2014 Article en page(s) : pp 559 - 574 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] éclipse (astronomie) [Termes IGN] harmonique sphérique [Termes IGN] lacet [Termes IGN] positionnement par GNSS [Termes IGN] rayonnement solaire Résumé : (Auteur) Systematic errors at harmonics of the GPS draconitic year have been found in diverse GPS-derived geodetic products like the geocenter Z -component, station coordinates, Y -pole rate and orbits (i.e. orbit overlaps). The GPS draconitic year is the repeat period of the GPS constellation w.r.t. the Sun which is about 351 days. Different error sources have been proposed which could generate these spurious signals at the draconitic harmonics. In this study, we focus on one of these error sources, namely the radiation pressure orbit modeling deficiencies. For this purpose, three GPS+GLONASS solutions of 8 years (2004–2011) were computed which differ only in the solar radiation pressure (SRP) and satellite attitude models. The models employed in the solutions are: (1) the CODE (5-parameter) radiation pressure model widely used within the International GNSS Service community, (2) the adjustable box-wing model for SRP impacting GPS (and GLONASS) satellites, and (3) the adjustable box-wing model upgraded to use non-nominal yaw attitude, specially for satellites in eclipse seasons. When comparing the first solution with the third one we achieved the following in the GNSS geodetic products. Orbits: the draconitic errors in the orbit overlaps are reduced for the GPS satellites in all the harmonics on average 46, 38 and 57 % for the radial, along-track and cross-track components, while for GLONASS satellites they are mainly reduced in the cross-track component by 39 %. Geocenter Z -component: all the odd draconitic harmonics found when the CODE model is used show a very important reduction (almost disappearing with a 92 % average reduction) with the new radiation pressure models. Earth orientation parameters: the draconitic errors are reduced for the X -pole rate and especially for the Y -pole rate by 24 and 50 % respectively. Station coordinates: all the draconitic harmonics (except the 2nd harmonic in the North component) are reduced in the North, East and Height components, with average reductions of 41, 39 and 35 % respectively. This shows, that part of the draconitic errors currently found in GNSS geodetic products are definitely induced by the CODE radiation pressure orbit modeling deficiencies Numéro de notice : A2014-287 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-014-0704-1 Date de publication en ligne : 07/03/2014 En ligne : https://doi.org/10.1007/s00190-014-0704-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=33190 [article]

Exemplaires(1)

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Annuaire du Bureau des Longitudes, guide de données astronomiques 2008, pour l'observation du ciel / Bureau des longitudes (2007)  

Public Titre : Annuaire du Bureau des Longitudes, guide de données astronomiques 2008, pour l'observation du ciel : calendriers, soleil, lune, planètes, astéroïdes, satellites, comètes, étoiles Type de document : Dictionnaire / Usuel Auteurs : Bureau des longitudes, Auteur ; Institut de mécanique céleste et de calcul des éphémérides (Observatoire de Paris), Auteur Editeur : Les Ulis : EDP Sciences Année de publication : 2007 Autre Editeur : IMC/BDL Importance : 374 p. Format : 15 x 24 cm ISBN/ISSN/EAN : 978-2-7598-0027-8 Langues : Français (fre) Descripteur : [Vedettes matières IGN] Astronomie fondamentale [Termes IGN] astéroïde [Termes IGN] calendrier [Termes IGN] comète [Termes IGN] éclipse (astronomie) [Termes IGN] éphémérides astronomiques [Termes IGN] étoile [Termes IGN] Lune [Termes IGN] planète [Termes IGN] satellite naturel [Termes IGN] soleil (étoile) Numéro de notice : 16880 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Usuel En ligne : https://gallica.bnf.fr/ark:/12148/bpt6k96339071?rk=21459;2 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=34837

Annuaire du Bureau des Longitudes, guide de données astronomiques 2007, pour l'observation du ciel calendriers, soleil, lune, planètes, astéroïdes, satellites, comètes, étoiles / Bureau des longitudes (2006)  

Public Titre : Annuaire du Bureau des Longitudes, guide de données astronomiques 2007, pour l'observation du ciel calendriers, soleil, lune, planètes, astéroïdes, satellites, comètes, étoiles Type de document : Dictionnaire / Usuel Auteurs : Bureau des longitudes, Auteur ; Institut de mécanique céleste et de calcul des éphémérides (Observatoire de Paris), Auteur Editeur : Les Ulis : EDP Sciences Année de publication : 2006 Autre Editeur : IMC/BDL Importance : 374 p. Format : 15 x 24 cm ISBN/ISSN/EAN : 978-2-86883-936-7 Langues : Français (fre) Descripteur : [Vedettes matières IGN] Astronomie fondamentale [Termes IGN] astéroïde [Termes IGN] calendrier [Termes IGN] comète [Termes IGN] éclipse (astronomie) [Termes IGN] éphémérides astronomiques [Termes IGN] étoile [Termes IGN] Lune [Termes IGN] planète [Termes IGN] satellite naturel [Termes IGN] soleil (étoile) Numéro de notice : 23668 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Usuel En ligne : https://gallica.bnf.fr/ark:/12148/bpt6k96300307?rk=21459;2 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=34996

Annuaire du Bureau des Longitudes, Guide de données astronomiques 2006, pour l'observation du ciel / Bureau des longitudes (2005)  

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Annuaire du Bureau des Longitudes, guide de données astronomiques 2005, pour l'observation du ciel / Bureau des longitudes (2004)  

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Annuaire du Bureau des Longitudes, éphémerides astronomiques 2004 / Bureau des longitudes (2003)  

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Annuaire du Bureau des Longitudes, éphémérides astronomiques 2003 / Bureau des longitudes (2002)  

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Annuaire du bureau des longitudes, éphémérides astronomiques 2002 / Bureau des longitudes (2001)  

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Annuaire du Bureau des Longitudes, éphémérides astronomiques 2001 / Bureau des longitudes (2000)  

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Les éclipses de soleil / Institut de mécanique céleste et de calcul des éphémérides (Observatoire de Paris) (1999)

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Annuaire du Bureau des Longitudes, éphémérides astronomiques 1993 / Bureau des longitudes (1992)  

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Annuaire du Bureau des Longitudes, éphémérides astronomiques 1990 / Bureau des longitudes (1989)  

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Eclipse annulaire de soleil, au Maroc, du 30 mai 1984 / Cnr (1984)

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