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Ajouter le résultat dans votre panier Affiner la recherche Interroger des sources externesBestimmung von Höhenänderungen in regionalen Netzen mit dem Global Positioning System / B. Görres (1996)
Titre : Bestimmung von Höhenänderungen in regionalen Netzen mit dem Global Positioning System Titre original : [Détermination des changements de hauteurs dans les réseaux régionaux avec le GPS] Type de document : Thèse/HDR Auteurs : B. Görres, Auteur Editeur : Francfort sur le Main : Institut für Angewandte Geodäsie Année de publication : 1996 Collection : DGK - C Sous-collection : Dissertationen num. 461 Importance : 102 p. Format : 21 x 30 cm Note générale : Bibliographie Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] antenne GPS
[Termes IGN] Bernese
[Termes IGN] correction troposphérique
[Termes IGN] données GPS
[Termes IGN] hauteur ellipsoïdale
[Termes IGN] réseau géodésique local
[Termes IGN] série temporelleIndex. décimale : 30.61 Systèmes de Positionnement par Satellites du GNSS Résumé : (Auteur)The Global Positioning System (GPS) provides the possibility to determine three-dimensional coordinates with very high accuracy. Promising applications present themselves for monitoring of deformations of the Earth surface. Until now applications have been focused on the horizontal components, because GPS yields them with higher accuracy. However, the height determination is strongly affected by problems related to the atmospheric refraction.
The main topic of this thesis is the development of strategies for the GPS field measurements and the processing to improve the accuracy of the vertical component. The necessary investigations are performed with data observed in a series of annual campaigns since 1993 within the GPS network HEIKO (Bestimmung von Ho'henanderungen in Eifel und KOelner Bucht). The area under investigation is a zone known for tectonic activity and anthropogenic height changes.
A detailed examination of the problems, which cause deviations in the height components, shows the importance of taking into account tropospheric refraction, phase center variations and multipath for the improvement of precise height determinations.
The studies using the "Bernese GPS Software" point out that extended observation sessions, calibration of GPS antennas and the use of low elevation satellite signals improve the repeatability of the height component. This is possible even when using standard models for the tropospheric refraction if tropospheric delay parameters are estimated. In addition it can be stated that a reliable accuracy for the height component can be given only by comparing results of several campaigns.
Using this concept the processing of the HEIKO network results in height changes of up to 25 mm/year with an average standard deviation of 2.4 mm/year. Comparisons with levelling results for identical stations in the area of brown coal mining lead to good agreement. This is of course only under the condion that gravity changes may be neglected.
The application of the proposed strategy has given accuracy results for GPS heights on distances of up to 100 km with a wrms of ± 2 mm, which is superior to the levelling accuracy on distances longer than 10 km. The conclusion points to an increasing importance of GPS for height determinations in extended networks.Numéro de notice : 28032 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=63379 Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 28032-01 30.61 Livre Centre de documentation Géodésie Disponible
Titre : Untersuchungen zu Erddeformationsmodellen für die Auswertung von geodätischen VLBI-Messungen Titre original : [Recherches sur les modèles de déformation de la terre pour l'utilisation des mesures géodésiques d'interférométrie de très longue base] Type de document : Thèse/HDR Auteurs : Rüdiger Haas, Auteur Editeur : Francfort sur le Main : Institut für Angewandte Geodäsie Année de publication : 1996 Collection : DGK - C Sous-collection : Dissertationen num. 466 Importance : 103 p. Format : 21 x 30 cm Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] analyse comparative
[Termes IGN] déformation de la croute terrestre
[Termes IGN] données ITGB
[Termes IGN] interférométrie à très grande base
[Termes IGN] marée terrestre
[Termes IGN] résonance
[Termes IGN] rotation de la Terre
[Termes IGN] surcharge atmosphérique
[Termes IGN] surcharge océaniqueIndex. décimale : 30.63 Télémétrie laser sur satellite, Télémétrie laser sur lune, VLBI Résumé : (Auteur) Within the last 20 years geodetic Very Long Baseline Interferometry [VLBI] has been developed as an important technique for geodesy and geophysics. The primary purpose of geodetic VLBI is the establishment of terrestrial and celestial reference frames, measurement of present day tectonic motion and monitoring of Earth rotation.
The accuracy in modeling the theoretical observations for the analysis of space geodetic measurements should ideally be higher than the instrumental precision. Latter is for today's VLBI-system in the millimeter range while the accuracy of modeling is in the centimeter range.
For this reason international efforts endeavor to raise the accuracy of modeling to the millimeter level. As part of this effort this thesis investigates the modeling of Earth deformation effects for the analysis of geodetic VLBI observations. Existing theoretical models for Earth tides, ocean loading and atmospheric loading and their actual application in the analysis of VLBI data are considered.
In a first step worst case simulations are computed in order to evaluate the magnitude of the effects when neglecting them in the analysis.
Then parameters of the Earth deformation models are estimated from VLBI data to test the sensitivity of the VLBI observations to these neglections. In the results the theoretically predicted resonance of the Earth tides is clearly visible. However, the empirical resonance period is significantly different from the theoretical one with a tendency towards an independently inferred value from gravimetry. The estimates for ocean loading show a tendency towards the values of a newly developed loading model. Estimates for atmospheric loading show good agreement with theoretical values. Based upon these considerations recommendations for the treatment of Earth deformation effects in the analysis of space geodetic observations are developed.
As a consequence the VLBI analysis software is extended following these recommendations. The results of these extensions are tested in the analysis of VLBI observations in three different VLBI networks. Results for baseline lengths and Earth rotation parameters are compared with the results that are achieved using the standard analysis software. The comparisons show, that short time and long time repeatability of baseline length measurements improves with the use of the extended analysis software. The accuracy of Earth rotation parameters can be improved, too. The use of the extended software removes diurnal and sub diurnal parts from high frequency Earth rotation parameters, which have been misinterpreted as Earth rotation variations.Numéro de notice : 27066 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=56315 Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 27066-01 30.63 Livre Centre de documentation Géodésie Disponible
Titre : Optimierung von Beobachtungsplänen in der Langbasisinterferometrie (VLBI) Titre original : [Optimisation de la prévision des observations d'interférométrie à très grande base] Type de document : Thèse/HDR Auteurs : H. Steufmehl, Auteur Editeur : Francfort sur le Main : Institut für Angewandte Geodäsie Année de publication : 1994 Collection : DGK - C Sous-collection : Dissertationen num. 406 Importance : 75 p. Format : 21 x 30 cm Note générale : Bibliographie Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] données ITGB
[Termes IGN] interférométrie à très grande base
[Termes IGN] matrice de covariance
[Termes IGN] optimisation (mathématiques)
[Termes IGN] programmation dynamiqueIndex. décimale : 30.63 Télémétrie laser sur satellite, Télémétrie laser sur lune, VLBI Résumé : (Auteur)Very Long Baseline Interferomerty (VLBI) is a method, which makes use of the radiation of extragalactical radio sources received by radio telescopes. The time difference between the arrival of the signals at two different observing stations is the prime VLBI-observable.
When several radio telescopes are linked to a network and have observed different sources for a time interval of normally 24 hours, we speak of a VLBI experiment. The sequence of the sources to be monitored is deter-mined by the observing schedule.
In order to obtain the best quality of determination of the target parameters, the variance/covariance matrix of the parameters should have an optimal design. This optimal design depends on the geometric configuration of the observations. Until now, the observations are selected interactively in a time-consuming process and without a precise knowledge of the quality of determination. In this thesis an algorithm is developed which allows the automatic creation of optimized VLBI observing schedules.
The analogies between the optimization of geodetic networks and the problem under consideration are dis-cussed and then the problem is presented as a 1 .order design problem where the observing stations must be linked optimally by time delay observations. It is a problem of sequentiel decisions, which can be solved on the basis of the process of dynamic optimization. The problem is analysed and a simplified numerical method of
solution suited for implementation in a computer program is derived.
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Furthermore, simulated observing schedules from the international observing program IRIS are presented. Some of those schedules have been used in real measurement campaigns. The observing positions have a tendency to accumulate in certain regions of the observable sky. The improvements of the accuracies range between 15% to 20% in comparison to the 'hand-made' schedules.
The significance of the new method is given on the one hand by the various possibilities of application while designing new networks and schedules and on the other hand by the much more efficient way of creating obser-ving schedules.Numéro de notice : 28077 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=63424 Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 28077-01 30.63 Livre Centre de documentation Géodésie Disponible
Titre : Digitale Komponenten von Fernerkundung, Photogrammetrie und Kartographie innerhalb der Geoinformatik sowie deren Beschreibung durch funktionsanalytische Mittel und Methoden Titre original : [Données numériques de télédétection, photogrammétrie et cartographie en géomatique et description au moyen d'une fonction analytique et de méthodes] Type de document : Thèse/HDR Auteurs : E. Pross, Auteur Editeur : Francfort sur le Main : Institut für Angewandte Geodäsie Année de publication : 1993 Collection : DGK - C Sous-collection : Dissertationen num. 414 Importance : 135 p. Format : 21 x 30 cm Note générale : Bibliographie Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Géomatique
[Termes IGN] analyse de données
[Termes IGN] cartographie
[Termes IGN] fonction analytique
[Termes IGN] géomatique
[Termes IGN] photogrammétrie
[Termes IGN] transformation linéaireNuméro de notice : 62411 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Thèse étrangère Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=61063 Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 62411-01 37.00 Livre Centre de documentation Géomatique Disponible
Titre : Radiointerferometrische Beobachtungen zur Bestimmung der Polbewegung unter Benutzung langer Nord-Süd-Basislinien Titre original : [Observations radiointerférométriques pour déterminer le mouvement polaire en utilisant les longues bases nord-sud] Type de document : Thèse/HDR Auteurs : Axel Nothnagel, Auteur Editeur : Francfort sur le Main : Institut für Angewandte Geodäsie Année de publication : 1991 Collection : DGK - C Sous-collection : Dissertationen num. 368 Importance : 93 p. Format : 21 x 30 cm Note générale : Bibliographie Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] données ITGB
[Termes IGN] interférométrie à très grande baseIndex. décimale : 30.63 Télémétrie laser sur satellite, Télémétrie laser sur lune, VLBI Résumé : (Auteur) For more than 15 years the technique of geodetic very long baseline interferometry (VLBI) 1s used for the determination of geodetic parameters. Pairs of radio telescopes as far apart as more than an Earth radius observe extragalactic radio sources, like quasars, which form an Ideal reference frame for studies of the Earth's rotation. The difference in arrival times of the signals at the stations yields a time delay, which is the principle observable in geodetic VLBI. A certain number of individual observations is necessary to allow the estimation of geodetic parameters like station coordinates and Earth orientation parameters. The geometry distribution of the observations within the segment of the sky mutually visible by pairs of radio telescopes is important for the quality of the least squares adjustment. This thesis describes a method of displaying both the observations and the horizon limitations of two stations forming a baseline in a unified System. This technique serves as a tool for improving the quality of observing schedules and it was used for the scheduling of two sets of measurements employing the Hartebeesthoek Radio Astronomy Observatory (HartRAO) in South Africa. In a series of 6 measurements separated by 5 to 10 days HartRAO observed together with two stations in the US and one station in Europe for Earth orientation determinations. These measurements had duration of 24 hours each. In the second series, daily measurements of only 2-3 hours duration with a single north-south baseline were performed for polar motion monitoring filling the gaps between the network measurements. Both series were observed in two consecutive years, 1986 and 1987, for periods of about 6 weeks each. In the first year the observing schedules were prepared with a conventional approach while in 1987 the technique of displaying the observations relative to a baseline reference point was used. The analysis of the data as described in this thesis showed that the standard deviations of the Earth orientation parameters improved by up to 30% by the use of the modified scheduling strategy. Numéro de notice : 28102 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=63449 Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 28102-01 30.63 Livre Centre de documentation Géodésie Disponible PermalinkPermalinkPermalinkPermalinkPermalinkPermalinkPermalinkPermalinkPermalinkPermalink
