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Observed changes in the Earth’s dynamic oblateness from GRACE data and geophysical models / Y. Sun in Journal of geodesy, vol 90 n° 1 (January 2016)  

Public [article]  inJournal of geodesy > vol 90 n° 1 (January 2016) . - pp 81 - 89 Titre : Observed changes in the Earth’s dynamic oblateness from GRACE data and geophysical models Type de document : Article/Communication Auteurs : Y. Sun, Auteur ; Pavel Ditmar, Auteur ; Riccardo Riva, Auteur Année de publication : 2016 Article en page(s) : pp 81 - 89 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] champ de pesanteur terrestre [Termes IGN] données GRACE [Termes IGN] données laser [Termes IGN] données TLS (télémétrie) [Termes IGN] incertitude des données [Termes IGN] masse d'eau [Termes IGN] rebond post-glaciaire Résumé : (auteur) A new methodology is proposed to estimate changes in the Earth’s dynamic oblateness (ΔJ2 or equivalently, −5√ΔC20) on a monthly basis. The algorithm uses monthly Gravity Recovery and Climate Experiment (GRACE) gravity solutions, an ocean bottom pressure model and a glacial isostatic adjustment (GIA) model. The resulting time series agree remarkably well with a solution based on satellite laser ranging (SLR) data. Seasonal variations of the obtained time series show little sensitivity to the choice of GRACE solutions. Reducing signal leakage in coastal areas when dealing with GRACE data and accounting for self-attraction and loading effects when dealing with water redistribution in the ocean is crucial in achieving close agreement with the SLR-based solution in terms of de-trended solutions. The obtained trend estimates, on the other hand, may be less accurate due to their dependence on the GIA models, which still carry large uncertainties. Numéro de notice : A2016-020 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0852-y En ligne : https://doi.org/10.1007/s00190-015-0852-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79467 [article]

Terrain complexity and uncertainties in grid-based digital terrain analysis / Q. Zhou in International journal of geographical information science IJGIS, vol 20 n° 10 (november 2006)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 20 n° 10 (november 2006) . - pp 1137 - 1147 Titre : Terrain complexity and uncertainties in grid-based digital terrain analysis Type de document : Article/Communication Auteurs : Q. Zhou, Auteur ; X. Liu, Auteur ; Y. Sun, Auteur Année de publication : 2006 Article en page(s) : pp 1137 - 1147 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique [Termes IGN] complexité [Termes IGN] incertitude géométrique [Termes IGN] modèle d'erreur [Termes IGN] modèle numérique de terrain [Termes IGN] pente [Termes IGN] relief Résumé : (Auteur) The objective of this research is to study the relationship between terrain complexity and terrain analysis results from grid-based digital elevation models (DEMs). The impact of terrain complexity represented by terrain steepness and orientation on derived parameters such as slope and aspect has been analysed. Experiments have been conducted to quantify the uncertainties created by digital terrain analysis algorithms. The test results show that (a) the RMSE of derived slope and aspect is negatively correlated with slope steepness; (b) the RMSE of derived aspect is more sensitive to terrain complexity than that of derived slope; and (c) the uncertainties in derived slope and aspect tend to be found in flatter areas, and decrease with increasing terrain complexity. The study shows that although primary surface parameters can be well defined mathematically, the implementation of those mathematical models in a GIS environment may generate considerable uncertainties related to terrain complexity. In general, when terrain is rugged with steep slopes, the uncertainty of derived parameters is quite minimal. While in flatter areas, the DEM-based derivatives, particularly the aspect, may contain a great amount of uncertainty, causing significant limitation in applying the analytical results. Copyright Taylor & Francis Numéro de notice : A2006-453 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1080/13658810600816573 En ligne : https://doi.org/10.1080/13658810600816573 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28177 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-06101	RAB	Revue	Centre de documentation	En réserve L003	Disponible
079-06102	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Spatial decision support systems for urban planning and management / S. Amer (29/03/1993)

Public contenu dans EGIS '93, Fourth European conference and exhibition on Geographical Information Systems, 1. Volume 1 / Janjaap Harts (1993) Titre : Spatial decision support systems for urban planning and management Type de document : Article/Communication Auteurs : S. Amer, Auteur ; R. Sluizas, Auteur ; Y. Sun, Auteur Editeur : Utrecht [Pays-Bas] : EGIS Foundation Année de publication : 29/03/1993 Conférence : EGIS 1993, 4th European conference and exhibition on Geographical Information Systems 29/03/1993 01/04/1993 Gênes Italie Importance : pp 116 - 124 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes d'information géographique [Termes IGN] aide à la décision [Termes IGN] gestion urbaine [Termes IGN] planification urbaine [Termes IGN] système d'information géographique Résumé : (Auteur) This paper shortly addresses some prospects and problems of effectively using GIS technology for urban management & spatial planning purposes. It will be argued that GIS technology will have to be embedded in the framework of Spatial Decision Support Systems (SDSS) to become a more complete tool for spatial planning & policy making. After a short discussion of mainstream urban GIS applications and a review of the principal characteristics of SDSS, two examples of recent ITC research in this field will be describes : a prototype SDSS for school siting and a knowledge based GIS for urban property valuation. Both examples are integrated systems composed of a GIS, a modelbase, a domain specific user interface and a proprietary, rule-based expert system shell. The examples clearly indicate that an SDSS provides an environment where the check-list like part of planning and the generation of alternative scenarios can be handled by the system thus releasing the planner to concentrate on strategic tasks. Whether SDSS' will evolve to become really intelligent planning machines', however, remains to be seen. Much will depend on the particular application and the political context of the decision making environment. Numéro de notice : C1993-019 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/INFORMATIQUE Nature : Communication Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=65546