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Affiner la recherche Interroger des sources externesDétermination du géopotentiel à haute résolution spatiale : apport des horloges atomiques et des algorithmes génétiques / Guillaume Lion (2018)
contenu dans 27èmes Journées de la Recherche de l'IGN / Journées Recherche de l'IGN 2018, 27es Journées (22 - 23 mars 2018; Cité Descartes, Champs-sur-Marne, France) (2018)
Titre : Détermination du géopotentiel à haute résolution spatiale : apport des horloges atomiques et des algorithmes génétiques Type de document : Article/Communication Auteurs : Guillaume Lion , Auteur ; David Coulot
Editeur : Saint-Mandé : Institut national de l'information géographique et forestière - IGN (2012-) Année de publication : 2018 Conférence : Journées Recherche de l'IGN 2018, 27es Journées 22/03/2018 23/03/2018 Champs-sur-Marne France programme sans actes Langues : Français (fre) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] algorithme génétique
[Termes IGN] horloge atomique
[Termes IGN] Massif central (France)
[Termes IGN] modèle de géopotentiel local
[Termes IGN] montagne
[Termes IGN] potentiel de pesanteur terrestre
[Termes IGN] précision centimétrique
[Termes IGN] réseau gravimétrique localRésumé : (Auteur) Les récentes avancées technologiques en matière de chronométrie permettent de réaliser des comparaisons d'horloge atomique à distance avec une incertitude proche de 10-18 en termes de fréquence relative. Avec une telle exactitude, ces instruments de mesure du temps permettent de faire de la géodésie à une précision centimétrique en mesurant des différences de géopotentiel directement. Dans cet exposé, nous nous intéresserons à la reconstruction du géopotentiel à haute résolution spatiale dans le Massif Central. À l’aide de tests synthétiques, nous discuterons l’apport de mesures horloge au sein d’un réseau gravimétrique existant en région montagneuse. Nous verrons ensuite comment optimiser la position des mesures horloge à l’aide d’algorithmes génétiques pour améliorer la détermination du géopotentiel. Numéro de notice : C2018-035 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Communication nature-HAL : ComSansActesPubliés-Unpublished DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91134 Documents numériques
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Détermination du géopotentiel à haute résolution spatiale... - diaporama de présentationAdobe Acrobat PDF
Titre : Optimization of atomic clock locations for the geopotential determination from gravimetric network Type de document : Article/Communication Auteurs : Guillaume Lion Editeur : Munich [Allemagne] : European Geosciences Union EGU Année de publication : 2018 Collection : Geophysical Research Abstracts, ISSN 1607-7962 num. 20 Conférence : EGU 2018, General Assembly 08/04/2018 13/04/2018 Vienne Autriche OA Abstracts only Note générale : EGU2018-11444 Langues : Anglais (eng) Résumé : (auteur) Clock comparisons with an uncertainty at the xx in terms of relative frequency can provide a new kind of measurement to improve our knowledge of Earth’s gravity field and geoid. Indeed, instead of using state-of-the-art Earth’s gravitational field models to predict frequency shifts between distant clocks, they could permit to determine geopotential differences directly at a centimeter-level accuracy. In our previous work (Lion et al., 2017) dealing with the geopotential determination at high spatial resolution in mountainous regions (e.g. the Massif Central – France), we have pointed out that clock-based geodetic observable can provide useful information at spatial scales beyond what is available from satellites and they could be used to fill areas not covered by the gravity data on the ground. Our synthetic simulations have shown that adding few clock-based potential data to a gravimetric data set can significantly improve the quality of reconstruction of the geopotential. Therefore, it turns out there is a large variety of possible clock distribution allowing to reduce the reconstruction residuals (bias and standard deviation), with different locations and number of clocks. In this work, we have investigated ways to optimize clock locations from a gravimetric data set in the Massif Central region in order to know where to put them to minimize the residuals and improve further the determination of the geopotential. To do that, we have used a multi-objective genetic algorithm (GA). A GA is an evolutionary algorithm inspired by the idea of natural evolution. Starting from a random initial population, with different clock distributions, the algorithm selects clock locations with good chances of reproduction and reproduces the new generation of clock locations using operations such as crossover and mutation. The process depends on some objectives we want to reach in order to solve the optimization problem, and it is repeated several times for a given number of generations or until a solution considered as optimum is found. We show how GA can help to provide optimal solutions for a problem with a fixed and variable number of clock locations. We discuss the effect of different parameters, such as the way to define the objectives and the constrains of the problem, the effect of the coverage and the quality of the gravimetric data and possible applications. Numéro de notice : C2018-072 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Communication nature-HAL : ComSansActesPubliés-Unpublished DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91464
Titre : Determination of a high spatial resolution geopotential model using atomic clock comparisons Type de document : Article/Communication Auteurs : Guillaume Lion Année de publication : 2017 Projets : FIRST-TF / , AdOC / , ITOC / Article en page(s) : pp 597 - 611 Note générale : Bibliographie
We gratefully acknowledge financial support from Labex FIRST-TF, ERC AdOC(Grant No. 617553 and EMRP ITOC (EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union).Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] Alpes (France)
[Termes IGN] champ de pesanteur local
[Termes IGN] collocation par moindres carrés
[Termes IGN] covariance
[Termes IGN] erreur systématique
[Termes IGN] horloge atomique
[Termes IGN] horlogerie
[Termes IGN] levé gravimétrique
[Termes IGN] Massif central (France)
[Termes IGN] modèle de géopotentiel local
[Termes IGN] qualité des donnéesRésumé : (Auteur) Recent technological advances in optical atomic clocks are opening new perspectives for the direct determination of geopotential differences between any two points at a centimeter-level accuracy in geoid height. However, so far detailed quantitative estimates of the possible improvement in geoid determination when adding such clock measurements to existing data are lacking. We present a first step in that direction with the aim and hope of triggering further work and efforts in this emerging field of chronometric geodesy and geophysics. We specifically focus on evaluating the contribution of this new kind of direct measurements in determining the geopotential at high spatial resolution (≈10 km). We studied two test areas, both located in France and corresponding to a middle (Massif Central) and high (Alps) mountainous terrain. These regions are interesting because the gravitational field strength varies greatly from place to place at high spatial resolution due to the complex topography. Our method consists in first generating a synthetic high-resolution geopotential map, then drawing synthetic measurement data (gravimetry and clock data) from it, and finally reconstructing the geopotential map from that data using least squares collocation. The quality of the reconstructed map is then assessed by comparing it to the original one used to generate the data. We show that adding only a few clock data points (less than 1% of the gravimetry data) reduces the bias significantly and improves the standard deviation by a factor 3. The effect of the data coverage and data quality on the results is investigated, and the trade-off between the measurement noise level and the number of data points is discussed. Numéro de notice : A2017-286 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0986-6 Date de publication en ligne : 11/01/2017 En ligne : http://dx.doi.org/10.1007/s00190-016-0986-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85319
in Journal of geodesy > vol 91 n° 6 (June 2017) . - pp 597 - 611[article]Documents numériques
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Determination of a high spatial resolution ... - pdf éditeurAdobe Acrobat PDF
Titre : Clock measurements to improve the geopotential determination Type de document : Article/Communication Auteurs : Guillaume Lion Editeur : Munich [Allemagne] : European Geosciences Union EGU Année de publication : 2017 Conférence : EGU 2017, General Assembly 23/04/2017 28/04/2017 Vienne Autriche https://www.egu2017.eu/ Note générale : LE POSTER N'EST PAS ENCORE ACCESSIBLE SUR HAL Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] champ de gravitation
[Termes IGN] géoïde altimétrique
[Termes IGN] horloge optique
[Termes IGN] Massif central (France)
[Termes IGN] méthode des moindres carrés
[Termes IGN] précision centimétrique
[Termes IGN] qualité des donnéesRésumé : (Auteur) Comparisons between optical clocks with an accuracy and stability approaching the 10-18 in term of relative frequency shift are opening new perspectives for the direct determination of geopotential at a centimeter-level accuracy in geoid height. However, so far detailed quantitative estimates of the possible improvement in geoid determination when adding such clock measurements to existing data are lacking. In this context, the present work aims at evaluating the contribution of this new kind of direct measurements in determining the geopotential at high spatial resolution (10 km). We consider the Massif Central area, marked by smooth, moderate altitude mountains and volcanic plateaus leading to variations of the gravitational field over a range of spatial scales. In such type of region, the scarcity of gravity data is an important limitation in deriving accurate high resolution geopotential models. We summarize our methodology to assess the contribution of clock data in the geopotential recovery, in combination with ground gravity measurements. We sample synthetic gravity and disturbing potential data from a spherical harmonics geopotential model, and a topography model, up to 10 km resolution; we also build a potential control grid. From the synthetic data, we estimate the disturbing potential by least-squares collocation. Finally, we assess the quality of the reconstructed potential by comparing it to that of the control grid. We show that adding only a few clock data reduces the reconstruction bias significantly and improves the standard deviation by a factor 3. We discuss the role of different parameters, such as the effect of the data coverage and data quality on these results, the trade-off between the measurement noise level and the number of data, and the optimization of the clock data network. Numéro de notice : C2017-062 Affiliation des auteurs : LASTIG+Ext (2016-2019) Thématique : POSITIONNEMENT Nature : Poster nature-HAL : Poster-sans-CL DOI : sans Date de publication en ligne : 15/07/2022 En ligne : https://hal.science/hal-03724673v1 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101283 Documents numériques
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Clock measurements ... - posterAdobe Acrobat PDF
Titre : Relativity and the metrology of time Type de document : Monographie Auteurs : Peter Wolf, Auteur Editeur : Sèvres : Bureau International des Poids et Mesures BIPM Année de publication : 1997 Collection : Monographies du BIPM num. 97-1 Importance : 169 p. Format : 21 x 30 cm Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Métrologie
[Termes IGN] chronométrie
[Termes IGN] Global Positioning System
[Termes IGN] métrologie
[Termes IGN] système de référence géodésique
[Termes IGN] temps
[Termes IGN] théorie de la relativitéIndex. décimale : 24.40 Métrologie Résumé : (Auteur) The motivation for this work is two-fold : the application of general relativity to the metrology of time on the one hand (part 2), and the use of the methods and technology of time metrology for tests of relativity on the other (part 3). In Part 2, a detailed theory for the treatment of the metrology of time in a relativistic context is developed. It provides mathematical expressions for application to the syntonisation and synchronisation of clocks and the realisation of the time coordinates of space-time reference systems. The theoretical expressions are developed to accuracies exceeding those of previous publications in order to accommodate any development in clock and time-transfer technology that can be expected in the near future.
Part 3 presents two original experiments which test the theory of special relativity using state-of-the-art time metrology. The first experiment uses data from clock comparisons between ground clocks and clocks on board the Global Positioning System (GPS) satellites to test the second postulate of special relativity (the universality of the speed of light). The experiment is sensitive to a possible anisotropy of the one-way speed of light in any spatial direction, and on a non-laboratory scale (baselines > 20000 km) and provides the most stringent limits for the anisotropy published up to date. The second is a proposal for a test of special relativity using a spacecraft that carries an onboard atomic clock and uses a two way time transfer system. The potential accuracy of such a test is evaluated for the ESA/RSA ExTRAS (Experiment on Timing Ranging and Atmospheric Sounding) experiment which was planned for launch in 1997 but is now "on hold".Numéro de notice : 62709 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Monographie Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=61114 Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 62709-01 24.40 Livre Centre de documentation En réserve M-103 Disponible
