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The employment of quasi-hexagonal grids in spherical harmonic analysis and synthesis for the earth's gravity field / Xingxing Li in Journal of geodesy, vol 96 n° 11 (November 2022)  

Public [article]  inJournal of geodesy > vol 96 n° 11 (November 2022) . - n° 89 Titre : The employment of quasi-hexagonal grids in spherical harmonic analysis and synthesis for the earth's gravity field Type de document : Article/Communication Auteurs : Xingxing Li, Auteur ; Jiancheng Li, Auteur ; Xiaochong Tong, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 89 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] champ de pesanteur terrestre [Termes IGN] harmonique sphérique [Termes IGN] icosahèdre [Termes IGN] système de grille globale discrète [Termes IGN] théorème de Legendre Résumé : (auteur) Numéro de notice : A2022-837 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-022-01653-6 Date de publication en ligne : 09/11/2022 En ligne : https://doi.org/10.1007/s00190-022-01653-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102034 [article]

Real-time GPS satellite orbit and clock estimation based on OpenMP / Kaifa Kuang in Advances in space research, vol 63 n° 8 (15 April 2019)  

Public [article]  inAdvances in space research > vol 63 n° 8 (15 April 2019) . - pp 2378 - 2386 Titre : Real-time GPS satellite orbit and clock estimation based on OpenMP Type de document : Article/Communication Auteurs : Kaifa Kuang, Auteur ; Shoujian Zhang, Auteur ; Jiancheng Li, Auteur Année de publication : 2019 Article en page(s) : pp 2378 - 2386 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] estimation statistique [Termes IGN] filtre de Kalman [Termes IGN] horloge du satellite [Termes IGN] modèle mathématique [Termes IGN] Open Multi-Processing [Termes IGN] orbite [Termes IGN] temps réel Résumé : (Auteur) Real-time precise GNSS satellite orbit and clock products are the prerequisite of real-time GNSS-based applications. To obtain real-time GNSS satellite orbit and clock, three approaches exist currently, namely, the prediction-estimation approach, the prediction-correction approach and the estimation approach. Different from the former two approaches, which are based on the predicted orbit, the last approach estimates orbit and clock in an integrated way, thus it is the most rigorous one. However, the simultaneously estimation of both orbit and clock parameters makes it very time-consuming. In this contribution, the extended Kalman filter with parallel computation proposed for real-time GPS satellite clock estimation (Gao et al., 2017) is introduced to improve the computational efficiency. In the introduced method, the epoch observations are processed sequentially and the covariance update process is accelerated with the Open Multi-Processing. With observation data from about 70 globally distributed stations spanning days 001–003 of 2018, the real-time GPS orbit and clock are estimated for validation. The epoch average processing time of the introduced method achieves around 2.9 s on average with 16 CPU cores, while that of the traditional method without Open Multi-Processing is about 4.1 s. When compare the estimated orbit and clock to the IGS final products, the daily constellation-mean RMS of orbit achieve 2.7, 5.7, 4.9 cm for the radial, along-track and cross-track respectively, while the daily constellation-mean STD of the clock is about 0.10 ns. The numerical experiments indicate that the introduced method is able to provide real-time sub-decimeter GPS orbit and clock within 10.0 s considering the time for data collection and corrections broadcast. Numéro de notice : A2019-170 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2019.01.009 Date de publication en ligne : 19/01/2019 En ligne : https://doi.org/10.1016/j.asr.2019.01.009 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92619 [article]

Consistent estimates of the dynamic figure parameters of the Earth / Wei Chen in Journal of geodesy, vol 89 n° 2 (February 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 2 (February 2015) . - pp 179 - 188 Titre : Consistent estimates of the dynamic figure parameters of the Earth Type de document : Article/Communication Auteurs : Wei Chen, Auteur ; Jiancheng Li, Auteur ; Jim Ray, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 179 - 188 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] champ de pesanteur terrestre [Termes IGN] ellipsoïde (géodésie) [Termes IGN] figure de la Terre [Termes IGN] masse de la Terre [Termes IGN] moment d'inertie Résumé : (auteur) The Earth’s dynamic figure parameters, namely the principal moments of inertia and dynamic ellipticities of the whole Earth, the fluid outer core and the solid inner core, are fundamental parameters for geodetic, geophysical and astronomical studies. This study aims to re-estimate the mass and the dynamic figure parameters of the Earth on the basis of some global gravity models (EGM2008, EIGEN-6C and EIGEN-6C2) recently released with unprecedented accuracies, as well as an improved value of the gravitational constant G recommended by the Committee on Data for Science and Technology (CODATA). With the potential coefficients of EGM2008, EIGEN-6C and EIGEN-6C2 rescaled to be consistent with the IAU (International Astronomical Union) and IAG (International Association of Geodesy) numerical standards, and other values of relevant parameters also being consistent with those numerical standards, we have obtained consistent estimates of the dynamic figure parameters of the stratified Earth using the theory described in Chen and Shen (J Geophys Res 115:B12419 2010). Our preferred principal moments of inertia for the whole Earth are A=(80,085.1±9.6)×1033 kg m2,B=(80,086.8±9.6)×1033 kg m2, and C=(80,349.0±9.6)×1033 kg m2, respectively, the accuracies being limited by the uncertainties of G and e (dynamic ellipticity of the whole Earth). Numéro de notice : A2015-333 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-014-0768-y Date de publication en ligne : 29/10/2014 En ligne : https://doi.org/10.1007/s00190-014-0768-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76658 [article]