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A bias-free geodetic boundary value problem approach to height datum unification / Alireza A. Ardalan in Journal of geodesy, vol 84 n° 2 (February 2010)  

Public [article]  inJournal of geodesy > vol 84 n° 2 (February 2010) . - pp 123 - 134 Titre : A bias-free geodetic boundary value problem approach to height datum unification Type de document : Article/Communication Auteurs : Alireza A. Ardalan, Auteur ; R. Karimi, Auteur ; Markku Poutanen, Auteur Année de publication : 2010 Article en page(s) : pp 123 - 134 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] cote géopotentielle [Termes IGN] erreur systématique [Termes IGN] Finlande [Termes IGN] géoïde local [Termes IGN] hauteur ellipsoïdale [Termes IGN] problème des valeurs limites [Termes IGN] réseau altimétrique local [Termes IGN] système de référence altimétrique Résumé : (Auteur) A geodetic boundary value problem (GBVP) approach has been formulated which can be used for solving the problem of height datum unification. The developed technique is applied to a test area in Southwest Finland with approximate size of 1.5° x 3° and the bias of the corresponding local height datum (local geoid) with respect to the geoid is computed. For this purpose the bias-free potential difference and gravity difference observations of the test area are used and the offset (bias) of the height datum, i.e., Finnish Height Datum 2000 (N2000) fixed to Normaal Amsterdams Peil (NAP) as origin point, with respect to the geoid is computed. The results of this computation show that potential of the origin point of N2000, i.e., NAP, is (62636857.68 1 0.5) (m2/s2) and as such is (0.191 1 0.003) (m) under the geoid defined by W 0 = 62636855.8 (m2/s2). As the validity test of our methodology, the test area is divided into two parts and the corresponding potential difference and gravity difference observations are introduced into our GBVP separately and the bias of height datums of the two parts are computed with respect to the geoid. Obtaining approximately the same bias values for the height datums of the two parts being part of one height datum with one origin point proves the validity of our approach. Besides, the latter test shows the capability of our methodology for patch-wise application. Copyright Springer Numéro de notice : A2010-107 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-009-0348-8 Date de publication en ligne : 10/10/2009 En ligne : https://doi.org/10.1007/s00190-009-0348-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30303 [article]

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Finite element method for solving geodetic boundary value problems / Z. Faskova in Journal of geodesy, vol 84 n° 2 (February 2010)  

Public [article]  inJournal of geodesy > vol 84 n° 2 (February 2010) . - pp 135 - 144 Titre : Finite element method for solving geodetic boundary value problems Type de document : Article/Communication Auteurs : Z. Faskova, Auteur ; Robert Cunderlik, Auteur ; Karol Mikula, Auteur Année de publication : 2010 Article en page(s) : pp 135 - 144 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] champ de pesanteur terrestre [Termes IGN] Earth Gravity Model 2008 [Termes IGN] géoïde [Termes IGN] méthode des éléments finis [Termes IGN] problème de Dirichlet [Termes IGN] problème des valeurs limites Résumé : (Auteur) The goal of this paper is to present the finite element scheme for solving the Earth potential problems in 3D domains above the Earth surface. To that goal we formulate the boundary-value problem (BVP) consisting of the Laplace equation outside the Earth accompanied by the Neumann as well as the Dirichlet boundary conditions (BC). The 3D computational domain consists of the bottom boundary in the form of a spherical approximation or real triangulation of the Earth’s surface on which surface gravity disturbances are given. We introduce additional upper (spherical) and side (planar and conical) boundaries where the Dirichlet BC is given. Solution of such elliptic BVP is understood in a weak sense, it always exists and is unique and can be efficiently found by the finite element method (FEM). We briefly present derivation of FEM for such type of problems including main discretization ideas. This method leads to a solution of the sparse symmetric linear systems which give the Earth’s potential solution in every discrete node of the 3D computational domain. In this point our method differs from other numerical approaches, e.g. boundary element method (BEM) where the potential is sought on a hypersurface only. We apply and test FEM in various situations. First, we compare the FEM solution with the known exact solution in case of homogeneous sphere. Then, we solve the geodetic BVP in continental scale using the DNSC08 data. We compare the results with the EGM2008 geopotential model. Finally, we study the precision of our solution by the GPS/levelling test in Slovakia where we use terrestrial gravimetric measurements as input data. All tests show qualitative and quantitative agreement with the given solutions. Copyright Springer Numéro de notice : A2010-108 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-009-0349-7 Date de publication en ligne : 13/10/2009 En ligne : https://doi.org/10.1007/s00190-009-0349-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30304 [article]

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266-2010021	SL	Revue	Centre de documentation	Revues en salle	Disponible