Détail de l'auteur
Auteur Fernando Sanso |
Documents disponibles écrits par cet auteur (17)
Ajouter le résultat dans votre panier Affiner la recherche Interroger des sources externesGravitational field modelling near irregularly shaped bodies using spherical harmonics: a case study for the asteroid (101955) Bennu / Blažej Bucha in Journal of geodesy, vol 95 n° 5 (May 2021)
Titre : Gravitational field modelling near irregularly shaped bodies using spherical harmonics: a case study for the asteroid (101955) Bennu Type de document : Article/Communication Auteurs : Blažej Bucha, Auteur ; Fernando Sanso, Auteur Année de publication : 2021 Article en page(s) : n° 56 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] astéroïde
[Termes IGN] champ de gravitation
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] convergence
[Termes IGN] harmonique sphérique
[Termes IGN] intégrale de NewtonRésumé : (auteur) We apply three spherical-harmonic-based techniques to deliver external gravitational field models of the asteroid (101955) Bennu within its circumscribing sphere. This region is known to be peculiar for external spherical harmonic expansions, because it may lead to a divergent series. The studied approaches are (i) spectral gravity forward modelling via external spherical harmonics, (ii) the least-squares estimation from surface gravitational data using external spherical harmonics and (iii) the combination of internal and external series expansions. While the first method diverges beyond any reasonable doubts, we show that the other two methods may ensure relative accuracy from ∼10−6 to 10−8 in the vicinity of Bennu. This is possible even with the second method, despite the fact that it relies on a single series of external spherical harmonics. Our main motivation was to study conceptual differences between spherical harmonic coefficients from satellite data (analogy to the first method) and from surface gravitational data (the second method). Such coefficients are available through the popular spherical-harmonic-based models of the Earth’s gravitational field and often are combined together. We show that the coefficients from terrestrial data may lead to a divergence effect of partial sums, though excellent accuracy can be achieved when such model is used in full. Under (presently) extreme but realistic conditions, the divergence effect of partial sums may affect many near-surface geoscientific applications, such as the geoid/quasigeoid computation or residual terrain modelling. Computer codes (Fortran, MATLAB) and data produced within the study are made freely available at http://edisk.cvt.stuba.sk/~xbuchab/. Numéro de notice : A2021-347 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-021-01493-w Date de publication en ligne : 22/04/2021 En ligne : https://doi.org/10.1007/s00190-021-01493-w Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97591
in Journal of geodesy > vol 95 n° 5 (May 2021) . - n° 56[article]
Titre : On the explicit determination of stability constants for linearized geodetic boundary value problems Type de document : Article/Communication Auteurs : Fernando Sanso, Auteur ; Giovanna Venuti, Auteur Année de publication : 2008 Article en page(s) : pp 909 - 916 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] problème des valeurs limitesRésumé : (Auteur) The theory of GBVPs provide the basis to the approximate methods used to compute global gravity models. A standard approximation procedure is least squares, which implicitly assumes that data, e.g. gravity disturbance and gravity anomaly, are given functions in L 2(S). We know that solutions in these cases exist, but uniqueness (and coerciveness which implies stability of the numerical solutions) is the real problem. Conditions of uniqueness for the linearized fixed boundary and Molodensky problems are studied in detail. They depend on the geometry of the boundary; however, the case of linearized fixed boundary BVP puts practically no constraint on the surface S, while the linearized Molodensky BVP requires the previous knowledge of very low harmonics, for instance up to degree 25, if we want the telluroid to be free to have inclinations up to 60°. Copyright Springer Numéro de notice : A2008-473 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-008-0221-1 En ligne : https://doi.org/10.1007/s00190-008-0221-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29542
in Journal of geodesy > vol 82 n° 12 (December 2008) . - pp 909 - 916[article]Exemplaires(2)
Code-barres Cote Support Localisation Section Disponibilité 266-08111 RAB Revue Centre de documentation En réserve L003 Disponible 266-08112 RAB Revue Centre de documentation En réserve L003 Disponible
Titre : The Bayesian detection of discontinuities in a polynomial regression and its application to the cycle-slip problem Type de document : Article/Communication Auteurs : M.C. DE Lacy, Auteur ; M. Reguzzoni, Auteur ; Fernando Sanso, Auteur ; Giovanna Venuti, Auteur Année de publication : 2008 Article en page(s) : pp 527 - 542 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] Bernese
[Termes IGN] correction du signal
[Termes IGN] phase GNSS
[Termes IGN] Ploynôme
[Termes IGN] quantité discrète
[Termes IGN] régression
[Termes IGN] réseau bayesien
[Termes IGN] traitement de données GNSSRésumé : (Auteur) This paper deals with the problem of detecting and correcting cycle-slips in Global Navigation Satellite System (GNSS) phase data by exploiting the Bayesian theory. The method is here applied to undifferenced observations, because repairing cycle-slips already at this stage could be a useful pre-processing tool, especially for a network of permanent GNSS stations. If a dual frequency receiver is available, the cycle-slips can be easily detected by combining two phase observations or phase and range observations from a single satellite to a single receiver. These combinations, expressed in a distance unit form, are completely free from the geometry and depend only on the ionospheric effect, on the electronic biases and on the initial integer ambiguities; since these terms are expected to be smooth in time, at least in a short period, a cycle-slip in one or both the two carriers can be modelled as a discontinuity in a polynomial regression. The proposed method consists in applying the Bayesian theory to compute the marginal posterior distribution of the discontinuity epoch and to detect it as a maximum a posteriori (MAP) in a very accurate way. Concerning the cycle-slip correction, a couple of simultaneous integer slips in the two carriers is chosen by maximazing the conditional posterior distribution of the discontinuity amplitude given the detected epoch. Numerical experiments on simulated and real data show that the discontinuities with an amplitude 2 or 3 times larger than the noise standard deviation are successfully identified. This means that the Bayesian approach is able to detect and correct cycle-slips using undifferenced GNSS observations even if the slip occurs by one cycle. A comparison with the scientific software BERNESE 5.0 confirms the good performance of the proposed method, especially when data sampled at high frequency (e.g. every 1 s or every 5 s) are available. Copyright Springer Numéro de notice : A2008-349 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-007-0203-8 En ligne : https://doi.org/10.1007/s00190-007-0203-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29342
in Journal of geodesy > vol 82 n° 9 (September 2008) . - pp 527 - 542[article]Exemplaires(2)
Code-barres Cote Support Localisation Section Disponibilité 266-08081 RAB Revue Centre de documentation En réserve L003 Disponible 266-08082 RAB Revue Centre de documentation En réserve L003 Disponible
Titre : The orthometric height and the holonomity problem Type de document : Article/Communication Auteurs : Fernando Sanso, Auteur ; Petr Vanicek, Auteur Année de publication : 2006 Article en page(s) : pp 225 - 232 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] altitude normale
[Termes IGN] altitude orthométrique
[Termes IGN] compensation
[Termes IGN] cote géopotentielle
[Termes IGN] pesanteur terrestre
[Vedettes matières IGN] AltimétrieRésumé : (Auteur) When height networks are being adjusted, many geodesists advocate the approach where the adjustment should be done by using geopotential numbers rather than the orthometric or normal heights used in practice. This is based on a conviction that neither orthometric nor normal heights can be used for the adjustment because these height systems are not holonomic, meaning–among other things–that height increments (orthometric or normal) when summed around a closed loop do not sum up to zero. If this was the case, then the two height systems could not be used in the adjustment; the non-zero loop closure would violate the basic, usually unspoken, assumption behind the adjustment, namely that the model claiming that height differences are observable is correct. In this paper, we prove in several different ways that orthometric and normal heights are theoretically just as holonomic as the geopotential numbers are, when they are obtained from levelled height differences using actual gravity values. This disposes of the argument that geopotential numbers should be used in the adjustment. Both orthometric and normal heights are equally qualified to be used in the adjustment directly. Copyright Springer Numéro de notice : A2006-365 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-005-0015-7 En ligne : https://doi.org/10.1007/s00190-005-0015-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28089
in Journal of geodesy > vol 80 n° 5 (August 2006) . - pp 225 - 232[article]Exemplaires(2)
Code-barres Cote Support Localisation Section Disponibilité 266-06071 RAB Revue Centre de documentation En réserve L003 Disponible 266-06072 RAB Revue Centre de documentation En réserve L003 Disponible
Titre : Bayesian classification by data augmentation Type de document : Article/Communication Auteurs : B. Regguzoni, Auteur ; Fernando Sanso, Auteur ; Giovanna Venuti, Auteur ; P.A. Brivio, Auteur Année de publication : 2003 Article en page(s) : pp 3961 - 3981 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image
[Termes IGN] axiome de Bayes
[Termes IGN] classification automatique d'objets
[Termes IGN] classification bayesienne
[Termes IGN] classification par maximum de vraisemblanceRésumé : (Auteur) A typical remote sensing data clustering is the maximum likelihood supervised procedure. It consists of the estimation of a suitable mixture of distributions, based on training samples only, and in the subsequent pixelbypixel classification, performed by maximizing the likelihood ratio. In this way all the information on the parameters of the distributions, contained in the unsurveyed samples, is lost. In the paper it is proposed to apply a suitable Bayesian method, known as a data augmentation algorithm, to fully exploit the information contained in the data. The method is presented in detail and applied to an elementary simulated example proving its capability of achieving almost the theoretical limit for the classification error. Comparisons with current classification methods as well as an application to a real dataset are reported. Numéro de notice : A2003-286 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/0143116031000103817 En ligne : https://doi.org/10.1080/0143116031000103817 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22581
in International Journal of Remote Sensing IJRS > vol 24 n° 20 (October 2003) . - pp 3961 - 3981[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 080-03201 RAB Revue Centre de documentation En réserve L003 Exclu du prêt PermalinkPermalinkPermalinkPermalinkPermalinkMare nostrum, Geomed report - 3 [Papers from working meeting in Graz, 7 - 9 June 1993] / R. Barzaghi (1992)
PermalinkPermalinkPermalinkPermalinkPermalink
