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A minimum energy condition for the inverse gravimetric problem / Olivier Jamet (2005)  

Public Titre : A minimum energy condition for the inverse gravimetric problem Type de document : Article/Communication Auteurs : Olivier Jamet , Auteur ; Michel Diament , Auteur Editeur : Berlin, Heidelberg, Vienne, New York, ... : Springer Année de publication : 2005 Collection : International Association of Geodesy Symposia, ISSN 0939-9585 num. 128 Conférence : IAG 2003, International Association of Geodesy General Assembly 30/06/2003 11/07/2003 Sapporo Japon Importance : pp 446 - 451 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] densité [Termes IGN] distribution spatiale [Termes IGN] espace de Hilbert [Termes IGN] levé gravimétrique [Termes IGN] méthode de réduction d'énergie [Termes IGN] problème inverse Résumé : (auteur) The problem of finding the density distribution of the Earth from gravity data is called the inverse gravimetric problem. It is well known that this problem has not a unique solution. A possible approach to force the uniqueness of the solution is to impose the solution to realize a minimum of energy, that is to be an equilibrium distribution. Several authors have considered this possibility by setting the energy to the sole energy of the potential field. In this paper, we show that such approaches correspond to the maximization of a quadratic form in the set of the density distributions considered as an Hilbert space. As a consequence, they cannot deliver realistic results without a constraint that reduces the set of possible density distributions to a bounded domain of the considered Hilbert space. Moreover, under such constraints, the result will necessarily be located at the boundary of the searched domain. In order to express a steady state condition leading to a freer solution, we propose to introduce a compression energy. We choose the state equation of Murnaghan that is known to apply reasonably in the upper mantle. We give an integral form of the compression energy and show that the resulting total energy admits a lower bound, which assess the existence of a solution. Finally, we derive a differential equation verified by that the absolute minima from the equilibrium equation under its local form. Numéro de notice : C2003-056 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : MATHEMATIQUE/POSITIONNEMENT Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl DOI : 10.1007/3-540-27432-4_76 En ligne : https://doi.org/10.1007/3-540-27432-4_76 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=103459

The proposed International DORIS Service / Pascal Willis (2005)  

Public Titre : The proposed International DORIS Service Type de document : Article/Communication Auteurs : Pascal Willis , Auteur ; Gilles Tavernier, Auteur ; Martine Feissel-Vernier , Auteur ; Franck G. Lemoine, Auteur ; Carey E. Noll, Auteur ; John Ries, Auteur ; Laurent Soudarin, Auteur Editeur : Berlin, Heidelberg, Vienne, New York, ... : Springer Année de publication : 2005 Collection : International Association of Geodesy Symposia, ISSN 0939-9585 num. 128 Conférence : IAG 2003, International Association of Geodesy General Assembly 30/06/2003 11/07/2003 Sapporo Japon Importance : pp 207 - 213 Note générale : bibliographie Langues : Français (fre) Résumé : (auteur) In 1999, an International DORIS Experiment was initiated under the aegis of the International Association of Geodesy. Since then, 3 new DORIS satellites have been launched carrying improved Doppler receivers. In addition, the DORIS tracking network has also been steadily improved. In 2001, a DORIS analysis campaign was launched. Several groups participated using different software and providing weekly and monthly time series of results, making them available on Internet. The goal of this paper is to discuss the status of the DORIS Pilot experiment, to analyze the progress made during the past 2 years and to propose the official creation within the IAG of an International DORIS Service (IDS). Such a service would operate in conjunction with the already existing IGS, IVS and ILRS as part of the proposed International Global Geodetic Observing System (IGGOS). Numéro de notice : C2003-054 Affiliation des auteurs : IGN+Ext (1940-2011) Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl DOI : 10.1007/3-540-27432-4_36 En ligne : https://doi.org/10.1007/3-540-27432-4_36 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102719