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Alothman, Abdulaziz. "Temporal variations of the earth's gravity field from GPS and SLR." Thesis, University of Newcastle Upon Tyne, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405083.
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Berkel, Paula. "Multiscale methods for the combined inversion of normal mode and gravity variations." Aachen Shaker, 2009. http://d-nb.info/997085304/04.
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Anjasmara, Ira Mutiara. "Spatio-temporal analysis of GRACE gravity field variations using the principal component analysis." Thesis, Curtin University, 2008. http://hdl.handle.net/20.500.11937/957.
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Gravity Recovery and Climate Experiment (GRACE) mission has amplified the knowledge of both static and time-variable part of the Earth’s gravity field. Currently, GRACE maps the Earth’s gravity field with a near-global coverage and over a five year period, which makes it possible to apply statistical analysis techniques to the data. The objective of this study is to analyse the most dominant spatial and temporal variability of the Earth’s gravity field observed by GRACE using a combination of analytical and statistical methods such as Harmonic Analysis (HA) and Principal Component Analysis (PCA). The HA is used to gain general information of the variability whereas the PCA is used to find the most dominant spatial and temporal variability components without having to introduce any presetting. The latter is an important property that allows for the detection of anomalous or a-periodic behaviour that will be useful for the study of various geophysical processes such as the effect from earthquakes. The analyses are performed for the whole globe as well as for the regional areas of: Sumatra- Andaman, Australia, Africa, Antarctica, South America, Arctic, Greenland, South Asia, North America and Central Europe. On a global scale the most dominant temporal variation is an annual signal followed by a linear trend. Similar results mostly associated to changing land hydrology and/or snow cover are obtained for most regional areas except over the Arctic and Antarctic where the secular trend is the prevailing temporal variability.Apart from these well-known signals, this contribution also demonstrates that the PCA is able to reveal longer periodic and a-periodic signal. A prominent example for the latter is the gravity signal of the Sumatra-Andaman earthquake in late 2004. In an attempt to isolate these signals, linear trend and annual signal are removed from the original data and the PCA is once again applied to the reduced data. For a complete overview of these results the most dominant PCA modes for the global and regional gravity field solutions are presented and discussed.
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Anjasmara, Ira Mutiara. "Spatio-temporal analysis of GRACE gravity field variations using the principal component analysis." Curtin University of Technology, Department of Spatial Sciences, 2008. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=18720.
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Gravity Recovery and Climate Experiment (GRACE) mission has amplified the knowledge of both static and time-variable part of the Earth’s gravity field. Currently, GRACE maps the Earth’s gravity field with a near-global coverage and over a five year period, which makes it possible to apply statistical analysis techniques to the data. The objective of this study is to analyse the most dominant spatial and temporal variability of the Earth’s gravity field observed by GRACE using a combination of analytical and statistical methods such as Harmonic Analysis (HA) and Principal Component Analysis (PCA). The HA is used to gain general information of the variability whereas the PCA is used to find the most dominant spatial and temporal variability components without having to introduce any presetting. The latter is an important property that allows for the detection of anomalous or a-periodic behaviour that will be useful for the study of various geophysical processes such as the effect from earthquakes. The analyses are performed for the whole globe as well as for the regional areas of: Sumatra- Andaman, Australia, Africa, Antarctica, South America, Arctic, Greenland, South Asia, North America and Central Europe. On a global scale the most dominant temporal variation is an annual signal followed by a linear trend. Similar results mostly associated to changing land hydrology and/or snow cover are obtained for most regional areas except over the Arctic and Antarctic where the secular trend is the prevailing temporal variability.Apart from these well-known signals, this contribution also demonstrates that the PCA is able to reveal longer periodic and a-periodic signal. A prominent example for the latter is the gravity signal of the Sumatra-Andaman earthquake in late 2004. In an attempt to isolate these signals, linear trend and annual signal are removed from the original data and the PCA is once again applied to the reduced data. For a complete overview of these results the most dominant PCA modes for the global and regional gravity field solutions are presented and discussed.
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KARIYAWASAM, THARANGA MANOHARI. "Theoretical Analysis of the Temperature Variations and the Krassovsky Ratio for Long Period Gravity Waves." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1212176032.
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Berkel, Paula [Verfasser]. "Multiscale Methods for the Combined Inversion of Normal Mode and Gravity Variations / Paula Berkel." Aachen : Shaker, 2009. http://d-nb.info/1159835357/34.
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Prevost, Paoline. "Extraction des variations spatio-temporelles du champ de gravité à partir des données de la mission spatiale GRACE : méthodes et applications géophysiques." Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEE017.
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L’estimation des variations spatio-temporelles du champ de gravité terrestre à partir des mesures de la mission satellitaire Gravity Recovery and Climate Experiment (GRACE) ont permis de mieux comprendre les redistributions de masse à des échelles de temps mensuelle, saisonnière ou décennale. Les solutions GRACE produites par différents centres, adoptant des stratégies de traitement différentes, conduisent à des résultats cohérents. Cependant, ces solutions présentent aussi des erreurs aléatoires et systématiques, celles-ci pouvant avoir une structure spatio-temporelle spécifique. Afin de réduire le bruit et améliorer la qualité des signaux géophysiques présents dans les données GRACE, plusieurs méthodes ont été proposées mais nécessitent en général des informations a priori sur la structure spatio-temporelle du bruit pourtant mal connue. Malgré les efforts considérables effectués pour améliorer la qualité des données GRACE pour des applications géophysiques de plus en plus fines, le filtrage du bruit reste une question problématique comme exposé dans le Chapitre 1. Dans cette thèse, nous proposons une approche différente, utilisant une technique de filtrage spatio-temporel, la Multichannel Singular Spectrum Analysis (M-SSA) décrite dans le Chapitre 2. La M-SSA est une méthode s’adaptant aux données, à variables multiples et non-paramétrique, qui exploite simultanément les corrélations spatiales et temporelles d’un champ géophysique. Nous utilisons la M-SSA sur 13 ans de données GRACE en harmoniques sphériques distribuées par cinq centres de calculs. Nous montrons que cette méthode permet d’extraire les modes de variabilité communs aux différentes solutions, et de réduire significativement les erreurs spatio-temporelles spécifiques à chaque solution et liées aux différentes stratégies de calculs. En particulier, cette méthode filtre efficacement les stries Nord-Sud dues, entre autres, aux imperfections des modèles de corrections des phénomènes connus. Dans le Chapitre 3, nous comparons notre solution GRACE à d’autres solutions en harmoniques sphériques et à des solutions basées sur des blocs de concentration de masse (mascons) utilisant des a priori sur la structure spatio-temporelle du signal géophysique. Nous comparons également les performances de notre solution M-SSA GRACE par rapport à d’autres solutions en calculant la déformation de surface induite par les variations de masse déduites des mesures GRACE et en la comparant avec des mesures indépendantes de déplacement provenant des stations du Global Navigation Satellite System (GNSS). Enfin, nous discutons dans le Chapitre 4 d’une application possible d’une solution GRACE améliorée pour répondre à des questions encore débattues liées au rebond post-glaciaire. Plus précisément, nous nous intéressons à la séparation du signal du rebond post-glaciaire, lié à la fonte ancienne, du signal de fonte récente des glaces dans la région de la Géorgie du SudMeasurements of the spatio-temporal variations of Earth’s gravity field recovered from the Gravity Recovery and Climate Experiment (GRACE) mission have led to unprecedented insights into large spatial mass redistribution at secular, seasonal, and sub-seasonal time scales. GRACE solutions from various processing centers, while adopting different processing strategies, result in rather coherent estimates. However, these solutions also exhibit random as well as systematic errors, with specific spatial and temporal patterns in the latter. In order to dampen the noise and enhance the geophysical signals in the GRACE data, several methods have been proposed. Among these, methods based on filtering techniques require a priori assumptions regarding the spatio-temporal structure of the errors. Despite the large effort to improve the quality of GRACE data for always finer geophysical applications, removing noise remains a problematic question as discussed in Chapter 1. In this thesis, we explore an alternative approach, using a spatio-temporal filter, namely the Multichannel Singular Spectrum Analysis (M-SSA) described in Chapter 2. M-SSA is a data-adaptive, multivariate, and non-parametric method that simultaneously exploits the spatial and temporal correlations of geophysical fields to extract common modes of variability. We perform an M-SSA simultaneously on 13 years of GRACE spherical harmonics solutions from five different processing centers. We show that the method allows for the extraction of common modes of variability between solutions, and removal of the solution-specific spatio-temporal errors arising from each processing strategies. In particular, the method filters out efficiently the spurious North-South stripes, most likely caused by aliasing of the imperfect geophysical correction models of known phenomena. In Chapter 3, we compare our GRACE solution to other spherical harmonics solutions and to mass concentration (mascon) solutions which use a priori information on the spatio-temporal pattern of geophysical signals. We also compare performance of our M-SSA GRACE solution with respect to others by predicting surface displacements induced by GRACE-derived mass loading and comparing results with independent displacement data from stations of the Global Navigation Satellite System (GNSS). Finally, in Chapter 4 we discuss the possible application of a refined GRACE solution to answer debated post-glacial rebound questions. More precisely, we focus on separating the post-glacial rebound signal related to past ice melting and the present ice melting in the region of South Georgia
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Werth, Susanna. "Calibration of the global hydrological model WGHM with water mass variations from GRACE gravity data." Phd thesis, Universität Potsdam, 2010. http://opus.kobv.de/ubp/volltexte/2010/4173/.
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Since the start-up of the GRACE (Gravity Recovery And Climate Experiment) mission in 2002 time dependent global maps of the Earth's gravity field are available to study geophysical and climatologically-driven mass redistributions on the Earth's surface. In particular, GRACE observations of total water storage changes (TWSV) provide a comprehensive data set for analysing the water cycle on large scales. Therefore they are invaluable for validation and calibration of large-scale hydrological models as the WaterGAP Global Hydrology Model (WGHM) which simulates the continental water cycle including its most important components, such as soil, snow, canopy, surface- and groundwater. Hitherto, WGHM exhibits significant differences to GRACE, especially for the seasonal amplitude of TWSV. The need for a validation of hydrological models is further highlighted by large differences between several global models, e.g. WGHM, the Global Land Data Assimilation System (GLDAS) and the Land Dynamics model (LaD).
For this purpose, GRACE links geodetic and hydrological research aspects. This link demands the development of adequate data integration methods on both sides, forming the main objectives of this work. They include the derivation of accurate GRACE-based water storage changes, the development of strategies to integrate GRACE data into a global hydrological model as well as a calibration method, followed by the re-calibration of WGHM in order to analyse process and model responses.
To achieve these aims, GRACE filter tools for the derivation of regionally averaged TWSV were evaluated for specific river basins. Here, a decorrelation filter using GRACE orbits for its design is most efficient among the tested methods. Consistency in data and equal spatial resolution between observed and simulated TWSV were realised by the inclusion of all most important hydrological processes and an equal filtering of both data sets. Appropriate calibration parameters were derived by a WGHM sensitivity analysis against TWSV. Finally, a multi-objective calibration framework was developed to constrain model predictions by both river discharge and GRACE TWSV, realised with a respective evolutionary method, the ε-Non-dominated-Sorting-Genetic-Algorithm-II (ε-NSGAII).
Model calibration was done for the 28 largest river basins worldwide and for most of them improved simulation results were achieved with regard to both objectives. From the multi-objective approach more reliable and consistent simulations of TWSV within the continental water cycle were gained and possible model structure errors or mis-modelled processes for specific river basins detected. For tropical regions as such, the seasonal amplitude of water mass variations has increased. The findings lead to an improved understanding of hydrological processes and their representation in the global model. Finally, the robustness of the results is analysed with respect to GRACE and runoff measurement errors. As a main conclusion obtained from the results, not only soil water and snow storage but also groundwater and surface water storage have to be included in the comparison of the modelled and GRACE-derived total water budged data. Regarding model calibration, the regional varying distribution of parameter sensitivity suggests to tune only parameter of important processes within each region. Furthermore, observations of single storage components beside runoff are necessary to improve signal amplitudes and timing of simulated TWSV as well as to evaluate them with higher accuracy.
The results of this work highlight the valuable nature of GRACE data when merged into large-scale hydrological modelling and depict methods to improve large-scale hydrological models.Das Schwerefeld der Erde spiegelt die Verteilung von Massen auf und unter der Erdoberfläche wieder. Umverteilungen von Erd-, Luft- oder Wassermassen auf unserem Planeten sind damit über eine kontinuierliche Vermessung des Erdschwerefeldes beobachtbar. Besonders Satellitenmissionen sind hierfür geeignet, da deren Umlaufbahn durch zeitliche und räumliche Veränderung der Schwerkraft beeinflusst wird. Seit dem Start der Satellitenmission GRACE (Gravity Recovery And Climate Experiment) im Jahr 2002 stellt die Geodäsie daher globale Daten von zeitlichen Veränderungen des Erdschwerefeldes mit hoher Genauigkeit zur Verfügung. Mit diesen Daten lassen sich geophysikalische und klimatologische Massenumverteilungen auf der Erdoberfläche studieren. GRACE liefert damit erstmals Beobachtungen von Variationen des gesamten kontinentalen Wasserspeichers, welche außerordentlich wertvoll für die Analyse des Wasserkreislaufes über große Regionen sind. Die Daten ermöglichen die Überprüfung von großräumigen mathematischen Modellen der Hydrologie, welche den natürlichen Kreislauf des Wassers auf den Kontinenten, vom Zeitpunkt des Niederschlags bis zum Abfluss in die Ozeane, nachvollziehbar machen. Das verbesserte Verständnis über Transport- und Speicherprozesse von Süßwasser ist für genauere Vorhersagen über zukünftige Wasserverfügbarkeit oder potentielle Naturkatastrophen, wie z.B. Überschwemmungen, von enormer Bedeutung. Ein globales Modell, welches die wichtigsten Komponenten des Wasserkreislaufes (Boden, Schnee, Interzeption, Oberflächen- und Grundwasser) berechnet, ist das "WaterGAP Global Hydrology Model" (WGHM). Vergleiche von berechneten und beobachteten Wassermassenvariationen weisen bisher insbesondere in der jährlichen Amplitude deutliche Differenzen auf. Sehr große Unterschiede zwischen verschiedenen hydrologischen Modellen betonen die Notwendigkeit, deren Berechnungen zu verbessern. Zu diesem Zweck verbindet GRACE die Wissenschaftsbereiche der Geodäsie und der Hydrologie. Diese Verknüpfung verlangt von beiden Seiten die Entwicklung geeigneter Methoden zur Datenintegration, welche die Hauptaufgaben dieser Arbeit darstellten. Dabei handelt es sich insbesondere um die Auswertung der GRACE-Daten mit möglichst hoher Genauigkeit sowie um die Entwicklung einer Strategie zur Integration von GRACE Daten in das hydrologische Modell. Mit Hilfe von GRACE wurde das Modell neu kalbriert, d.h. Parameter im Modell so verändert, dass die hydrologischen Berechnungen besser mit den GRACE Beobachtungen übereinstimmen. Dabei kam ein multikriterieller Kalibrieralgorithmus zur Anwendung mit dem neben GRACE-Daten auch Abflussmessungen einbezogen werden konnten. Die Modellkalibierung wurde weltweit für die 28 größten Flusseinzugsgebiete durchgeführt. In den meisten Fällen konnte eine verbesserte Berechnung von Wassermassenvariationen und Abflüssen erreicht werden. Hieraus ergeben sich, z.B. für tropische Regionen, größere saisonale Variationen. Die Ergebnisse führen zu einem verbesserten Verständnis hydrologischer Prozesse. Zum Schluss konnte die Robustheit der Ergebnisse gegenüber Fehlern in GRACE- und Abflussmessungen erfolgreich getestet werden. Nach den wichtigsten Schlussfolgerungen, die aus den Ergebnissen abgeleitet werden konnten, sind nicht nur Bodenfeuchte- und Schneespeicher, sondern auch Grundwasser- und Oberflächenwasserspeicher in Vergleiche von berechneten und GRACE-beobachteten Wassermassenvariationen einzubeziehen. Weiterhin sind neben Abflussmessungen zusätzlich Beobachtungen von weiteren hydrologischen Prozessen notwendig, um die Ergebnisse mit größerer Genauigkeit überprüfen zu können. Die Ergebnisse dieser Arbeit heben hervor, wie wertvoll GRACE-Daten für die großräumige Hydrologie sind und eröffnen eine Methode zur Verbesserung unseres Verständnisses des globalen Wasserkreislaufes.
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Lorant, Foldvary. "Geoid Height Variations Caused by Geophysical Fluids and Their Possible Recovery by Future Satellite Gravity Missions." 京都大学 (Kyoto University), 2001. http://hdl.handle.net/2433/150837.
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Elsaka, Basem [Verfasser]. "Simulated satellite formation flights for detecting the temporal variations of the Earth's gravity field / Basem Elsaka." Bonn : Universitäts- und Landesbibliothek Bonn, 2019. http://d-nb.info/1199005320/34.
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Badinger, Harald, and de Clairfontaine Aurélien Fichet. "Trade Balance Dynamics and Exchange Rates: In Search of the J-Curve Using a Structural Gravity Approach." WU Vienna University of Economics and Business, 2018. http://epub.wu.ac.at/5971/1/wp256.pdf.
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This paper uses a structural gravity approach, specifying currency movements as trade cost component to derive an empirical trade balance model, which incorporates multilateral resistance terms and accounts for the cross-country variation in the exchange rate pass-through into import and export prices. The model is estimated using quarterly bilateral trade flows between 47 countries over the period 2010Q1-2017Q2, disaggregated into 97 commodity groups. Our results support the existence of an "aggregate" J-curve, pooled over commodity groups; at the same time they point to considerable heterogeneity in the trade balance dynamics across industries below the surface of aggregate data.Series: Department of Economics Working Paper Series
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Venkat, Ratnam Madineni, and Christoph Jacobi. "Study on stratospheric gravity wave activity: global and seasonal variations deduced from the CHAllenging Minisatellite Payload (CHAMP)-GPS Satellite." Wissenschaftliche Mitteilungen des Leipziger Instituts für Meteorologie ; 30 = Meteorologische Arbeiten aus Leipzig ; 8 (2003), S. 136-148, 2003. https://ul.qucosa.de/id/qucosa%3A15246.
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Global analyses of gravity wave activity in the stratosphere are presented for the first time using German Low Earth Orbit (LEO) satellite CHAMP. Temperature profiles obtained from CHAMP/GPS radio occultations are first compared with ground based instruments. In general, good agreement is found between these different techniques. Monthly mean Ep values of potential energy, Ep values, being a measure of gravity wave activity, which is estimated with radiosonde observations are compared with CHAMP/GPS data and found that radiosonde observed Ep values are higher than those estimated with radio occultations. There exists a strong diurnal variation of gravity wave activity. From the global morphology of gravity wave activity, large values Ep are noticed even at mid latitudes during winter months besides the tropical latitudes but not during equinoxes suggesting that wave activity, especially at stratospheric heights, is not only modulated due to orography (mountain/lee waves) but mainly depends on seasonal variations at respective latitudes. Latitudinal and vertical variation of gravity wave activity reveals the existence of large Ep values below 25 km and low values in between 25 and 30 km in all the seasons near equator. During southern hemisphere winter, large values are noticed. During equinoxes, these values are nearly same between northern and southern hemispheres (NH and SH) at mid-latitudes. During the months of solstices, Ep distribution involves a larger hemispheric asymmetry at middle and higher latitudes. Large values of Ep are noticed at SH polar latitudes during Sep-Oct months and the latitude range is wider (±300° latitude in both the hemispheres) with large Ep values in all the seasons except winter.Zum ersten Mal werden globale Analysen der Schwerewellenaktivität, bestimmt unter Verwendung des CHAMP LEO-Satelliten, vorgestellt. Temperaturprofile der CHAMP/RO-Okkultationen werden zunächst mit bodengestützten Messungen verglichen. Generell ist die Übereinstimmung gut. Monatliche Mittelwerte der potentiellen Energie Ep, die als Maß für Schwerewellenaktivität gilt, wurden aus Radisonden- und CHAMP-Messungen bestimmt, wobei die CHAMP-Daten höhere Werte lieferten. Es existiert eine deutlicher Tagesgang von Ep. Die globale Morphologie der Schwerewellenaktivität zeigt hohe Werte nicht nur am Äquator, sondern auch in mittleren Breiten, dies aber nicht während der Äquinoktien. Dies weist darauf hin, dass Schwerewelleaktivität nicht nur orographisch angetrieben ist, sondern in verschiedenen Breiten vom Jahresgang abhängt. Die Breiten- und Höhenabhängigkeit der Schwerewellenaktivität zeigt zwischen 25 und 30 km niedrige, unterhalb von 25 km hohe Werte von Ep am Äquator. Während des Winters in der Südhemisphäre sind die Werte hoch, während zu den Äquinoktien hohe Werte in mittleren Breiten beider Hemisphären zu finden sind. Während der Solstitien zeigt die Ep-Verteilung stärkere hemisphärische Asymmetrie. Hohe Werte von Ep werden während des südpolaren Frühjahrs gemessen. Der äquatoriale Bereich hoher Varianz ist in allen Jahreszeiten außer im Winter breit (±300°).
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Malhotra, Garima. "HF Radar Observations of Inter-Annual variations in Mid-Latitude Mesospheric Winds." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/78084.
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The equatorial Quasi Biennial Oscillation (QBO) is known to be an important source of inter-annual variability at mid and high latitudes in both hemispheres. Coupling between QBO and the polar vortex has been extensively studied over the past few decades, however, less is known about QBO influences in the mid-latitude mesosphere. One reason for this is the relative lack of instrumentation available to study mesospheric dynamics at mid-latitudes. In this study, we have used the mid-latitude SuperDARN HF radar at Saskatoon (52.16 N, -106.53 E) to study inter-annual variation in mesospheric winds. The specific aim was to determine whether or not a Quasi Biennial signature could be identified in the Saskatoon mesosphere, and if so, to understand its relationship with the equatorial stratospheric QBO. To achieve this goal, a technique has been developed which extracts meteor echoes from SuperDARN near-range gates and then applies least-squares fitting across all radar beam directions to calculate hourly averages of the zonal and meridional components of the mesospheric neutral wind. Subsequent analysis of 13 years (2002-2014) of zonal wind data produced using this technique indicates that there is indeed a significant QBO signature present in Saskatoon mesospheric winds during late winter (Jan-Feb). This mesospheric QBO signature is in opposite phase with the equatorial stratospheric QBO, such that when QBO (at 50 hPa) is in its easterly (westerly) phase, the late winter winds in Saskatoon mesosphere become more (less) westerly. To further examine the source of the signature, we also analyzed winds in the Saskatoon stratosphere between 5 hPa and 70 hPa using the ECMWF ERA-Interim reanalysis data set, and found that the late winter stratospheric winds become less (more) westerly when QBO is easterly (westerly). This QBO signature in the mid-latitude stratospheric winds is essentially the same as that observed for the polar vortex in previous studies but it is opposite in phase to the mid-latitude mesospheric QBO. We therefore conclude that filtering of gravity waves through QBO-modulated stratospheric winds plays a major role in generating the mesospheric QBO signature we have identified in the Saskatoon HF radar data. When the Saskatoon stratospheric winds are anomalously westward during easterly QBO, the gravity waves having westward momentum might be filtered out, depositing a net eastward momentum in the mesosphere as they propagate upwards. This would result in increased westerly mesospheric winds at Saskatoon. The opposite would happen when the equatorial QBO is westerly.Master of Science
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Creutzfeldt, Noah Angelo Benjamin. "The effect of water storages on temporal gravity measurements and the benefits for hydrology." Phd thesis, Universität Potsdam, 2010. http://opus.kobv.de/ubp/volltexte/2010/4857/.
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Temporal gravimeter observations, used in geodesy and geophysics to study variation of the Earth’s gravity field, are influenced by local water storage changes (WSC) and – from this perspective – add noise to the gravimeter signal records. At the same time, the part of the gravity signal caused by WSC may provide substantial information for hydrologists. Water storages are the fundamental state variable of hydrological systems, but comprehensive data on total WSC are practically inaccessible and their quantification is associated with a high level of uncertainty at the field scale.
This study investigates the relationship between temporal gravity measurements and WSC in order to reduce the hydrological interfering signal from temporal gravity measurements and to explore the value of temporal gravity measurements for hydrology for the superconducting gravimeter (SG) of the Geodetic Observatory Wettzell, Germany.
A 4D forward model with a spatially nested discretization domain was developed to simulate and calculate the local hydrological effect on the temporal gravity observations. An intensive measurement system was installed at the Geodetic Observatory Wettzell and WSC were measured in all relevant storage components, namely groundwater, saprolite, soil, top soil and snow storage. The monitoring system comprised also a suction-controlled, weighable, monolith-filled lysimeter, allowing an all time first comparison of a lysimeter and a gravimeter. Lysimeter data were used to estimate WSC at the field scale in combination with complementary observations and a hydrological 1D model. Total local WSC were derived, uncertainties were assessed and the hydrological gravity response was calculated from the WSC. A simple conceptual hydrological model was calibrated and evaluated against records of a superconducting gravimeter, soil moisture and groundwater time series. The model was evaluated by a split sample test and validated against independently estimated WSC from the lysimeter-based approach.
A simulation of the hydrological gravity effect showed that WSC of one meter height along the topography caused a gravity response of 52 µGal, whereas, generally in geodesy, on flat terrain, the same water mass variation causes a gravity change of only 42 µGal (Bouguer approximation). The radius of influence of local water storage variations can be limited to 1000 m and 50 % to 80 % of the local hydro¬logical gravity signal is generated within a radius of 50 m around the gravimeter.
At the Geodetic Observatory Wettzell, WSC in the snow pack, top soil, unsaturated saprolite and fractured aquifer are all important terms of the local water budget. With the exception of snow, all storage components have gravity responses of the same order of magnitude and are therefore relevant for gravity observations. The comparison of the total hydrological gravity response to the gravity residuals obtained from the SG, showed similarities in both short-term and seasonal dynamics. However, the results demonstrated the limitations of estimating total local WSC using hydrological point measurements.
The results of the lysimeter-based approach showed that gravity residuals are caused to a larger extent by local WSC than previously estimated. A comparison of the results with other methods used in the past to correct temporal gravity observations for the local hydrological influence showed that the lysimeter measurements improved the independent estimation of WSC significantly and thus provided a better way of estimating the local hydrological gravity effect. In the context of hydrological noise reduction, at sites where temporal gravity observations are used for geophysical studies beyond local hydrology, the installation of a lysimeter in combination with complementary hydrological measurements is recommended.
From the hydrological view point, using gravimeter data as a calibration constraint improved the model results in comparison to hydrological point measurements. Thanks to their capacity to integrate over different storage components and a larger area, gravimeters provide generalized information on total WSC at the field scale. Due to their integrative nature, gravity data must be interpreted with great care in hydrological studies. However, gravimeters can serve as a novel measurement instrument for hydrology and the application of gravimeters especially designed to study open research questions in hydrology is recommended.Zeitabhängigen Gravimetermessungen, die in der Geodäsie und der Geophysik eingesetzt werden, um Variationen des Erdschwerefelds zu messen, werden durch lokale Wasserspeicheränderungen beeinflusst und verursachen – aus dieser Perspektive – ein hydrologisches Störsignal in den Gravimetermessungen. Gleichzeitig bietet der Teil des Gravimetersignals, der durch Wasserspeicheränderungen hervorgerufen wird, das Potential wichtige Informationen über hydrologische Speicher zu gewinnen, da zwar Wasserspeicher eine grundlegende Zustandsgröße hydrologischer Systeme darstellt, jedoch ihre Quantifizierung mit einem hohen Maß an Unsicherheiten auf der Feldskala behaftet ist. Diese Studie untersucht die Beziehung zwischen zeitabhängigen Gravimetermessungen und Wasserspeicheränderungen, um die Gravimetermessungen von dem hydrologischen Störsignal zu bereinigen und um den Nutzen der Gravimetermessungen für die Hydrologie zu erkunden. Dies geschieht am Beispiel des Supraleitgravimeters (SG) des Geodätischen Observatoriums Wettzell in Deutschland. Ein 4D Vorwärtsmodel mit einer räumlich genesteten Diskretisierungsdomäne wurde entwickelt, um die lokalen hydrologischen Masseneffekte auf Gravimetermessungen zu simulieren. Des Weiteren wurde ein intensives Messsystem am Geodätischen Observatorium Wettzell installiert, um die Wasserspeicheränderungen in allen relevanten Speicherkomponenten, also im dem Grundwasser, in der ungesättigten Zone und im Schneespeicher zu messen. Das Monitoringsystem beinhaltete auch einen wägbaren, monolithischen Lysimeter mit Matrixpotentialübertragung, der es uns ermöglichte, zum ersten Mal einen Lysimeter direkt mit einem Gravimeter zu vergleichen. Die Lysimetermessungen wurden in Kombination mit komplementären hydrologischen Beobachtungen und einem 1D-Modell verwendet, um die Wasserspeicheränderungen auf der Feldskala zu bestimmen. Die Gesamtwasserspeicheränderungen wurden bestimmt, Unsicherheiten abgeschätzt und der hydrologische Masseneffekt auf Gravimetermessungen berechnet. Schlussendlich wurde ein einfaches, konzeptionelles, hydrologisches Modell mittels der Zeitreihen von dem SG, Bodenfeuchte- und Grundwassermessungen kalibriert und evaluiert. Das Modell wurde durch einen “Split-Sample-Test” evaluiert und basierend auf unabhängig bestimmten Wasserspeicheränderungen bestimmt auf Grundlage der Lysimetermessungen validiert. Die Simulation des hydrologischen Masseneffektes auf Gravimetermessungen zeigte, dass Wasserspeicheränderungen von einem Meter Höhe entlang der Topographie, einen Erdschwereeffekt von 52 µGal hervorriefen, während in der Geodäsie im Allgemeinen die gleiche Wassermassenvariation in flachem Terrain eine Erdschwereeffekt von nur 42 µGal (Bouguer-Platte) hervorruft. Der Einflussradius der lokalen Wasserspeicheränderungen kann auf 1000 m begrenzt werden, und 50 % bis 80 % des lokalen hydrologischen Erdschweresignals wird in einem Radius von 50 m um den Gravimeter generiert. Wasserspeichervariationen in der Schneedecke, im Oberboden, dem ungesättigten Saprolith und im gelüfteten Aquifer, sind allesamt wichtige Größen der lokalen Wasserbilanz. Mit der Ausnahme von Schnee beeinflussen alle Speicheränderungen die Gravimetermessungen in derselben Größenordnung und sind daher für die Gravimetermessungen von Bedeutung. Ein Vergleich des lokalen hydrologischen Gravitationseffektes mit den SG Residuen zeigte sowohl ereignisbezogene als auch saisonalen Übereinstimmungen. Weiterhin zeigten die Ergebnisse jedoch auch die Grenzen bei der Bestimmung der gesamten lokalen Wasserspeichervariationen mithilfe hydrologischer Punktmessungen auf. Die Ergebnisse des Lysimeter-basierten Ansatzes zeigten, dass SG Residuen mehr noch, als bisher aufgezeigt, durch lokale Wasserspeicheränderungen hervorgerufen werden. Ein Vergleich der Resultate mit anderen Methoden, die in der Vergangenheit zur Korrektur zeitabhängiger Erdschwerebeobachtungen durch Bestimmung des lokalen hydrologischen Masseneffekte verwendet wurden, zeigte, dass die unabhängige Berechnung von Wasserspeicheränderungen durch Lysimetermessungen erheblich verbessert werden kann und dass diese somit eine verbesserte Methode zur Bestimmung des lokalen hydrologischen Erdschwereeffekts darstellt. Die Installation eines Lysimeters ist somit im Zusammenhang mit einer Reduzierung des hydrologischen Störsignals und an Standorten, wo zeitabhängige Erdschwerebeobachtungen für geophysikalische Studien, die über die lokale Hydrologie hinausgehen verwendet werden, zu empfehlen. Aus hydrologischer Sicht zeigte diese Studie, dass die Verwendung von zeitabhängigen Gravimetermessungen als Kalibrierungsdaten die Modellergebnisse im Vergleich zu hydrologischen Punktmessungen verbesserten. Auf Grund ihrer Fähigkeit, über verschiedene Speicherkomponenten und ein größeres Gebiet zu integrieren, bieten Gravimeter verallgemeinerte Informationen über die Gesamtwasserspeicherveränderungen auf der Feldskala. Diese integrative Eigenschaft macht es notwendig, Erdschweredaten in hydrologischen Studien mit großer Vorsicht zu interpretieren. Dennoch können Gravimeter der Hydrologie als neuartiges Messinstrument dienen und die Nutzung von Gravimetern, die speziell für die Beantwortung noch offener Forschungsfragen der Hydrologie entwickelt wurden wird hier empfohlen.
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Volařík, Tomáš. "Redukce atmosferickych vlivu z observace supravodivych gravimetru." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-355644.
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This dissertation is focused on a study of selected environmental effects influencing terrestrial gravity observations. Global geopotential models were used to compute quantities of the disturbing gravity field and its variations during time period. Furthermore, analyses of an atmospherical and hydrological effects on the gravity observations were provided. The computation was realized at the station Pecný, however the concept was proved and compared with data from station Strasbourg. Consequently, the results were discussed with respect to quasigeoid modelling established from gravity and astrogeodetic measurements. The result and recommendations for future research are exposed.
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Zenner, Lieselotte [Verfasser], Roland [Akademischer Betreuer] Pail, Reiner [Akademischer Betreuer] Rummel, and Maik [Akademischer Betreuer] Thomas. "Atmospheric and Oceanic Mass Variations and their role for gravity field determination / Lieselotte Zenner. Gutachter: Reiner Rummel ; Roland Pail ; Maik Thomas. Betreuer: Roland Pail." München : Universitätsbibliothek der TU München, 2013. http://d-nb.info/1032313250/34.
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Zenner, Lieselotte Verfasser], Roland [Akademischer Betreuer] [Pail, Reiner [Akademischer Betreuer] Rummel, and Maik [Akademischer Betreuer] Thomas. "Atmospheric and Oceanic Mass Variations and their role for gravity field determination / Lieselotte Zenner. Gutachter: Reiner Rummel ; Roland Pail ; Maik Thomas. Betreuer: Roland Pail." München : Universitätsbibliothek der TU München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:91-diss-20130306-1121142-0-9.
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Horwath, Martin. "Zur Ermittlung geophysikalischer Massensignale mit Schwerefeldmissionen: Eine Analyse des gegenwärtigen Standes am Beispiel der Antarktis." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2008. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1203684703310-42192.
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Die neuen Schwerefeld-Satellitenmissionen CHAMP (Challenging Minisatellite Payload), GRACE (Gravity Recovery and Climate Experiment) und GOCE (Gravity Field and Steady-State Ocean Circulation Explorer) können wesentlich zur Erforschung und Beobachtung des Systems Erde beitragen. Die Antarktis als ein Schlüsselglied im globalen Klimasystem bietet dabei besondere Herausforderungen. GRACE hat hier das Potential, zeitliche Massenänderungen (unter anderem der Eismasse) zu beobachten. Methoden zur Auswertung der Missionsdaten befinden sich gegenwärtig in einem intensiven Entwicklungsprozess, zu dem die vorliegende Arbeit beitragen soll. Inhaltlicher Schwerpunkt ist die Nutzung von GRACE zur Ermittlung zeitlicher Massenvariationen in der Antarktis. Die Analysen erfolgen in erster Linie aus der Position eines Nutzers von Standard-Missionsprodukten, betreffen aber grundsätzlich den gesamten Auswerteprozess. Nach einer Einführung werden zunächst die Hintergründe der Arbeit ausgeführt (Kapitel 2), speziell die theoretischen Grundlagen zu Massen- und Schwerefeldvariationen, Phänomene geophysikalischer Massenvariationen und die neuen Schwerefeldmissionen mit ihrem Potential zur Beobachtung solcher Massenvariationen. Ein Hauptteil der Arbeit behandelt die Frage, welche Signale und Fehler in den Schwerefeldlösungen der Missionen enthalten sind (Kapitel 3). Zunächst werden dazu gegenwärtige Prozessierungskonzepte zur Erstellung von CHAMP- und GRACE-Schwerefeldlösungen skizziert und die GRACE-Monatslösungen des GeoForschungsZentrums Potsdam als ein Standard-GRACE-Produkt vorgestellt. Es folgen verschiedene Analysen zur Fehlerstruktur der Schwerefeldlösungen, wobei insbesondere die Fehlerstruktur von GRACE-Monatslösungen anhand ihres Zeitverhaltens empirisch untersucht werden. Als eine Ursache empirisch festgestellter, aber durch Fehlermodelle nicht vollständig beschriebener Fehlerstrukturen werden schließlich Alias-Effekte von unmodellierten zeitlichen Variationen auf die geschätzten räumlichen Variationen qualitativ und quantitativ beschrieben und diskutiert. Ein zweiter Hauptteil untersucht geophysikalische Rückschlüsse aus GRACE-Schwerefeldlösungen mit Anwendung auf die Schätzung antarktischer Eismassensignale (Kapitel 4). Methoden zur Schätzung von Massensignalen aus den Schwerefeldlösungen werden systematisch zusammengestellt und teilweise weiterentwickelt. Die praktische Anwendung dieser Methoden zur Schätzung von Eismassenänderungen des Antarktischen Eisschildes und seiner großen Eiseinzugsgebiete wird erklärt. Ein Schwerpunkt liegt auf der Untersuchung der unterschiedlichen Mechanismen, die zu Fehlern der geschätzten Massensignale führen, sowie auf der Abschätzung dieser Fehler. Im Lichte der gewonnenen Einsichten in die methodischen Unsicherheiten der angewandten Analysetechniken erfolgt schließlich die Präsentation und Diskussion der Ergebnisse, einschließlich eines Vergleichs mit bisher veröffentlichten Massenbilanzresultaten. Möglichkeiten zu methodischen Verbesserungen, die in den vorangegangenen Untersuchungen deutlich werden, aber über den Rahmen der Arbeit hinausgehen, werden in einem eigenen Kapitel (Kapitel 5) diskutiert. Dies betrifft sowohl solche Verbesserungen, die bereits auf der Basis der gegenwärtigen GRACE-Monatslösungen möglich sind, als auch Verbesserungen in der Generierung dieser Monatslösungen oder, allgemeiner, in der GRACE-Prozessierung. Die Kombination der GRACE-Daten mit komplementären Beobachtungen und Modellen spielt in den unterschiedlichen Stadien der GRACE-Datenanalyse eine Schlüsselrolle. In Bezug auf die Trennung antarktischer Massensignale werden Kombinationsstrategien nochmals gesondert diskutiert. Schließlich werden die Hauptergebnisse der Arbeit nochmals zusammengefasst und eingeordnet (Kapitel 6)The new gravity field satellite missions CHAMP (Challenging Minisatellite Payload), GRACE (Gravity Recovery and Climate Experiment) and GOCE (Gravity Field and Steady-State Ocean Circulation Explorer) can provide essential contributions to the study and the monitoring of the Earth system. Hereby, Antarctica as a key element of the climate system offers particular challenges. GRACE has the potential to observe temporal variations of masses such as ice masses, in particular. Methods to analyse the mission data are currently in a process of intensive development. The present work aims to contribute to this process. The focus is on the use of GRACE to determine temporal mass variations in Antarctica. The analyses are carried out from the viewpoint of a standard product user. Nonetheless, they concern the entire process of GRACE data analysis. After an introduction, the background of the work is explained, in particular the theoretical fundamentals of mass and gravity field variations, the phenomena of geophysical mass variations and the new gravity field missions with their potential to observe these variations (chapter 2). One main part of the work (chapter 3) treats the question which signals and errors are contained in the missions' gravity field solutions (chapter 3). Current CHAMP and GRACE processing approaches are outlined. The GRACE monthly solutions by GeoForschungsZentrum Potsdam are introduced. Subsequently, different analyses about error structures of gravity field mission solutions are presented. In particular, an empirical analysis of time-variations of the GRACE monthly solutions reveals error structures which are not completely described by error models. As one cause of this discrepancy, alias effects of unmodelled temporal variations on the spatial patterns of the solutions are discussed qualitatively and quantitatively. Another main part of the work (chapter 4) investigates geophysical inferences from the GRACE monthly solutions, with Antarctica taken as a case study. Methods to estimate mass signals are systematised and partly enhanced. The practical applications of these methods for the estimation of Antarctic ice mass changes is explained. The different error mechanisms are investigated in detail, and corresponding errors are assessed. The results about Antarctic ice mass changes are then presented, compared to previous results and discussed in the light of the remaining methodological uncertainties. The studies reveal directions for methodological improvements, and so, related ideas are discussed in a separate chapter (chapter 5). They concern both the analysis of current GRACE monthly solutions and the generation of these solutions, or, more generally, the GRACE processing. The combination of GRACE data with complementary observations and models plays a key role in the different levels of GRACE data analysis. Combination strategies are, hence, once more discussed with regard to Antarctic mass signals. Finally, the main results of the work are summarised and discussed in a broader context
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Horwath, Martin. "Zur Ermittlung geophysikalischer Massensignale mit Schwerefeldmissionen: Eine Analyse des gegenwärtigen Standes am Beispiel der Antarktis." Doctoral thesis, Technische Universität Dresden, 2007. https://tud.qucosa.de/id/qucosa%3A24104.
Full textAbstract:
Die neuen Schwerefeld-Satellitenmissionen CHAMP (Challenging Minisatellite Payload), GRACE (Gravity Recovery and Climate Experiment) und GOCE (Gravity Field and Steady-State Ocean Circulation Explorer) können wesentlich zur Erforschung und Beobachtung des Systems Erde beitragen. Die Antarktis als ein Schlüsselglied im globalen Klimasystem bietet dabei besondere Herausforderungen. GRACE hat hier das Potential, zeitliche Massenänderungen (unter anderem der Eismasse) zu beobachten. Methoden zur Auswertung der Missionsdaten befinden sich gegenwärtig in einem intensiven Entwicklungsprozess, zu dem die vorliegende Arbeit beitragen soll. Inhaltlicher Schwerpunkt ist die Nutzung von GRACE zur Ermittlung zeitlicher Massenvariationen in der Antarktis. Die Analysen erfolgen in erster Linie aus der Position eines Nutzers von Standard-Missionsprodukten, betreffen aber grundsätzlich den gesamten Auswerteprozess. Nach einer Einführung werden zunächst die Hintergründe der Arbeit ausgeführt (Kapitel 2), speziell die theoretischen Grundlagen zu Massen- und Schwerefeldvariationen, Phänomene geophysikalischer Massenvariationen und die neuen Schwerefeldmissionen mit ihrem Potential zur Beobachtung solcher Massenvariationen. Ein Hauptteil der Arbeit behandelt die Frage, welche Signale und Fehler in den Schwerefeldlösungen der Missionen enthalten sind (Kapitel 3). Zunächst werden dazu gegenwärtige Prozessierungskonzepte zur Erstellung von CHAMP- und GRACE-Schwerefeldlösungen skizziert und die GRACE-Monatslösungen des GeoForschungsZentrums Potsdam als ein Standard-GRACE-Produkt vorgestellt. Es folgen verschiedene Analysen zur Fehlerstruktur der Schwerefeldlösungen, wobei insbesondere die Fehlerstruktur von GRACE-Monatslösungen anhand ihres Zeitverhaltens empirisch untersucht werden. Als eine Ursache empirisch festgestellter, aber durch Fehlermodelle nicht vollständig beschriebener Fehlerstrukturen werden schließlich Alias-Effekte von unmodellierten zeitlichen Variationen auf die geschätzten räumlichen Variationen qualitativ und quantitativ beschrieben und diskutiert. Ein zweiter Hauptteil untersucht geophysikalische Rückschlüsse aus GRACE-Schwerefeldlösungen mit Anwendung auf die Schätzung antarktischer Eismassensignale (Kapitel 4). Methoden zur Schätzung von Massensignalen aus den Schwerefeldlösungen werden systematisch zusammengestellt und teilweise weiterentwickelt. Die praktische Anwendung dieser Methoden zur Schätzung von Eismassenänderungen des Antarktischen Eisschildes und seiner großen Eiseinzugsgebiete wird erklärt. Ein Schwerpunkt liegt auf der Untersuchung der unterschiedlichen Mechanismen, die zu Fehlern der geschätzten Massensignale führen, sowie auf der Abschätzung dieser Fehler. Im Lichte der gewonnenen Einsichten in die methodischen Unsicherheiten der angewandten Analysetechniken erfolgt schließlich die Präsentation und Diskussion der Ergebnisse, einschließlich eines Vergleichs mit bisher veröffentlichten Massenbilanzresultaten. Möglichkeiten zu methodischen Verbesserungen, die in den vorangegangenen Untersuchungen deutlich werden, aber über den Rahmen der Arbeit hinausgehen, werden in einem eigenen Kapitel (Kapitel 5) diskutiert. Dies betrifft sowohl solche Verbesserungen, die bereits auf der Basis der gegenwärtigen GRACE-Monatslösungen möglich sind, als auch Verbesserungen in der Generierung dieser Monatslösungen oder, allgemeiner, in der GRACE-Prozessierung. Die Kombination der GRACE-Daten mit komplementären Beobachtungen und Modellen spielt in den unterschiedlichen Stadien der GRACE-Datenanalyse eine Schlüsselrolle. In Bezug auf die Trennung antarktischer Massensignale werden Kombinationsstrategien nochmals gesondert diskutiert. Schließlich werden die Hauptergebnisse der Arbeit nochmals zusammengefasst und eingeordnet (Kapitel 6).The new gravity field satellite missions CHAMP (Challenging Minisatellite Payload), GRACE (Gravity Recovery and Climate Experiment) and GOCE (Gravity Field and Steady-State Ocean Circulation Explorer) can provide essential contributions to the study and the monitoring of the Earth system. Hereby, Antarctica as a key element of the climate system offers particular challenges. GRACE has the potential to observe temporal variations of masses such as ice masses, in particular. Methods to analyse the mission data are currently in a process of intensive development. The present work aims to contribute to this process. The focus is on the use of GRACE to determine temporal mass variations in Antarctica. The analyses are carried out from the viewpoint of a standard product user. Nonetheless, they concern the entire process of GRACE data analysis. After an introduction, the background of the work is explained, in particular the theoretical fundamentals of mass and gravity field variations, the phenomena of geophysical mass variations and the new gravity field missions with their potential to observe these variations (chapter 2). One main part of the work (chapter 3) treats the question which signals and errors are contained in the missions' gravity field solutions (chapter 3). Current CHAMP and GRACE processing approaches are outlined. The GRACE monthly solutions by GeoForschungsZentrum Potsdam are introduced. Subsequently, different analyses about error structures of gravity field mission solutions are presented. In particular, an empirical analysis of time-variations of the GRACE monthly solutions reveals error structures which are not completely described by error models. As one cause of this discrepancy, alias effects of unmodelled temporal variations on the spatial patterns of the solutions are discussed qualitatively and quantitatively. Another main part of the work (chapter 4) investigates geophysical inferences from the GRACE monthly solutions, with Antarctica taken as a case study. Methods to estimate mass signals are systematised and partly enhanced. The practical applications of these methods for the estimation of Antarctic ice mass changes is explained. The different error mechanisms are investigated in detail, and corresponding errors are assessed. The results about Antarctic ice mass changes are then presented, compared to previous results and discussed in the light of the remaining methodological uncertainties. The studies reveal directions for methodological improvements, and so, related ideas are discussed in a separate chapter (chapter 5). They concern both the analysis of current GRACE monthly solutions and the generation of these solutions, or, more generally, the GRACE processing. The combination of GRACE data with complementary observations and models plays a key role in the different levels of GRACE data analysis. Combination strategies are, hence, once more discussed with regard to Antarctic mass signals. Finally, the main results of the work are summarised and discussed in a broader context.
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Burton, Howard Steven. "On the Palatini variation and connection theories of gravity." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0009/NQ38225.pdf.
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Eshagh, Mehdi. "On Satellite Gravity Gradiometry." Doctoral thesis, Stockholm : Skolan för arkitektur och samhällsbyggnad, Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10429.
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Yamamoto, Keiko. "Study on regional scale mass variation using GRACE satellite gravity data." 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/59309.
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Doole, Stuart Harvey. "Steady gravity waves on flows with vorticity : bifurcation theory and variational principles." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357537.
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Bourda, Géraldine. "Rotation terrestre et variations du champ de gravité : étude et apport des missions CHAMP et GRACE." Observatoire de Paris, 2004. https://tel.archives-ouvertes.fr/tel-00008286.
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Bourda, Géraldine. "Rotation terrestre et Variations du champ de gravité : Etude et apport des missions CHAMP et GRACE." Phd thesis, Observatoire de Paris, 2004. http://tel.archives-ouvertes.fr/tel-00008286.
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La distribution des masses à l'intérieur de la Terre régit la vitesse de rotation terrestre, ainsi que le comportement de l'axe de rotation terrestre dans la Terre, et dans l'espace. Ces distributions de masses peuvent être mesurées depuis l'espace grâce aux satellites artificiels, dont l'orbitographie donne accès à la détermination du champ de gravité terrestre. Par conséquent, les variations temporelles du champ de gravité peuvent être reliées aux variations des paramètres d'orientation terrestre (via le tenseur d'inertie). Des progrès considérables ont été effectués ces dernières années dans la modélisation des effets des couches fluides. Et de nos jours, les mesures d'orientation terrestre dans l'espace obtenues par Interférométrie à très Longue Base (VLBI) ont une exactitude meilleure qu'une milliseconde de degré. Ceci permet de progresser dans la connaissance de la dynamique globale de la Terre. Mon travail de thèse a eu pour but d'utiliser la mesure du champ de gravité et de ses variations comme outil pour compléter la modélisation de la rotation terrestre. D'une part, en vue de l'utilisation des mesures du satellite GRACE, d'une grande précision, nous avons effectué des comparaisons précises des méthodes numériques d'intégration d'orbite de Cowell et d'Encke dans le logiciel GINS du GRGS. D'autre part, nous avons établi les liens théoriques entre les Paramètres d'Orientation Terrestres (EOP) et les variations des coefficients du champ de gravité. Ainsi, nous avons utilisé les données de variations temporelles des coefficients de degré 2 du géopotentiel pour en déduire leur influence sur la longueur du jour, le mouvement du pôle et la précession de l'équateur.
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Dean, Bruce H. "Variational results and solutions in gauge gravity and a bifurcation analysis of black hole orbital dynamics." Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=859.
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Thesis (Ph. D.)--West Virginia University, 1999.Title from document title page. Document formatted into pages; contains ix, 223 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 214-223) and index.
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Masseguin, Christophe. "Implication de l'aquaporine 1 et de la Na, K ATPase dans l'adaptation des plexus choroïdes aux variations de la gravité." Saint-Etienne, 2002. http://www.theses.fr/2002STET004T.
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L'homeostasie cerebrale, hydro-ionique et volumique, doit etre maintenueface aux variations de pressions hydrostatiques et/ou osmotiques imposees par des conditions environnementales extremes comme la micro- ou l'hypergravite. Ces conditions font fluctuer l'irrigation sanguine cephalique, et, consecutivement, les flux de liquide cephalo-rachidien (LCR). Pour evaluer la reponse adaptative des plexus choroides, principale source de LCR, au vol spatial, a la suspension anti-orthostatique, - qui simule certains effets du vol spatial -, et a l'hypergravite, nous avons etudie l'ultrastructure de l'epithelium choroidien, element de la barriere Sang- LCR. Nous avons ensuite localise et analyse les expressions de l'ezrine, qui est un bon marqueur de polarite et de differentiation du domaine apical dans ces cellules, et de l'anhydrase carbonique II (ACII), de la Na, LCR et de l'aquaporine 1 (AQP1) qui sont marqueurs d'activite fonctionnelle, impliques dans les mecanismes de production du LCR. Par une approche in situ, nous avons analyse semi-quantitativement l'expression proteique et genique de la Na, KATPase et de l'AQP1, choisies pour leurs activites de transports ioniques et/ou hydrique. Des resultats originaux ont ete obtenus chez le rat en developpement, adulte ou age et chez le rat spontanement hypertendu (rat SHR). Une etude preliminaire a permis de noter que l'expression de la Na, KATPase est augmentee chez les souris transgeniques AQP-/-. Ces donnees ont servi de reference pour analyser les reponses choroidiennes aux variations de gravite. Par ce travail, nous montrons que le vol spatial et la suspension anti- orthostatique entrainent, apres une periode d'adaptation, une diminution de l'expression des deux modules et de leur ARN messagers, confirmant l'effet inhibiteur de ces conditions environnementales sur la production de LCR. Par contre, les effets de l'hypergravite ont ete plus variables, en fonction de la duree, du niveau et de la vitesse de rotation.
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Boy, Jean-Paul. "Effets des surcharges atmospheriques sur les variations de gravite et les deplacements de surface de la terre." Université Louis Pasteur (Strasbourg) (1971-2008), 2000. http://www.theses.fr/2000STR13232.
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La gravimetrie est un des outils privilegies d'investigation de la dynamique globale et interne terrestre. L'atmosphere constitue une des principales sources de perturbations des mesures de gravite en surface empechant la detection de phenomenes profonds et de faible amplitude, comme les modes vibratoires du noyau liquide et de la graine solide. Les donnees des gravimetres sont usuellement corrigees des effets de pression au moyen d'une modelisation empirique simple, consistant en la determination d'une admittance barometrique entre les mesures locales de la gravite et de la pression atmospherique. Nous calculons a l'aide des fonctions de green, traduisant la reponse spatiale de la terre solide aux surcharges atmospheriques, et des champs globaux fournis par les centres de prevision meteorologiques europeen (ecmwf) et americain (ncep), la contribution de l'atmosphere aux variations de gravite et deplacements en surface. Cette estimation physique permet une reduction significative et systematique, pour des periodes comprises entre quelques jours et une centaine de jours, des residus de gravite en surface mesuree par differents gravimetres cryogeniques par rapport a la correction empirique au moyen de la seule donnee de pression locale. Par contre, les incertitudes des mesures gps ne permettent pas une reduction systematique des donnees de deplacements en surface. La precision des gravimetres cryogeniques nous permet egalement d'examiner la reponse des oceans aux variations de pression atmospheriques. Nous prouvons que l'hypothese classique du barometre non-inverse (les oceans transmettent integralement la pression atmospheriques sur le fond) ne constitue pas un modele physique valide. Par contre, l'hypothese du barometre inverse (les oceans compensent statiquement les variations de pression) permet une estimation satisfaisante de cette reponse pour des periodes comprises entre quelques jours et une centaine de jours.
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Tung, Sui, and 董帥. "Co-seismic and post-seismic gravity variation associated with the 2008 M=8 Wenchuan earthquake : implication for crustal dynamics." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/197833.
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Longmen Shan Mountain Belt is a prominent orogeny along the eastern margin of the Tibetan plateau. Its current deformation has significant implications for the Cenozoic tectonics of the Tibetan plateau. The M=8 Wenchuan earthquake substantially ruptured the Longmen Shan mountain in 2008. Numerous tectonics and rheological implications are concluded by this event on crustal dynamics along the eastern margin of the Tibetan plateau. Several high-resolution gravity surveys were conducted before and after the event to investigate the regional isostasy and crustal dynamics. From 2008 to 2011, four gravimetric surveys were carried out along two profiles across southern and northern Longmen Shan from the Sichuan Basin to the Songpan-Graze Terrane. The Bouguer gravity anomalies drop from -162 mGal to -431 mGal in the Aba Basin with a steep gradient of 0.84 mGal/km. There is a significant increase of crustal thickness from 40 km in the Sichuan to more than 60 km in the Tibetan plateau.
Negative isostatic anomaly of -30 mGal over 150 km of the Songpan-Graze Terrane infers an over-compensation of excess crustal thickness up to 20 km. Hence, upward isostatic rebound is resulted and coupled with on-going crustal movement. Gravity values change significantly before and after the Wenchuan earthquake, ranging from -1.2 mGal to 0.7 mGal near the epicentral area. Significant thrust slip of 7.5m and normal slip of 4.5 m were simulated along the Beichuan fault and Wenchuan fault by an elastic dislocation theory. The co-existence of thrusting and normal faulting implies both compressional and extensional settings along Longmen Shan. The normal slip corroborates a large-scale crustal extension, lending support to a model with the inflation of lower crustal flow. The two-year post-seismic gravity variations were more than 0.1 mGal near the epicentral area. About 25% of them could be attributed to viscoelastic mantle relaxation. The dynamics topography along the eastern margin of the plateau is proposed to be a consequence of lower crustal flow squeezed by isostatic rebound and topographic load. The strong Yangtze Block is thought to obstruct the crustal flow horizontally and direct it to flow upward beneath Longmen Shan. The steep topography and seismicity along Longmen Shan are then resulted probably from the vertical stress induced in this upward flow.published_or_final_version
Earth Sciences
Doctoral
Doctor of Philosophy
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Rosat, Séverine. "Variations temporelles de la gravité en relation avec la dynamique interne de la Terre - Apport des gravimètres supraconducteurs." Phd thesis, Université Louis Pasteur - Strasbourg I, 2004. http://tel.archives-ouvertes.fr/tel-00144439.
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La dynamique et la structure interne de la Terre sont mal contraintes en profondeur, car les signaux induits en surface, de faible amplitude et basse fréquence, atteignent le seuil de détection des sismomètres. La gravimétrie devient un outil privilégié d'investigation de la Terre profonde aux longues périodes. Les variations temporelles de la gravité sont enregistrées en permanence par des gravimètres relatifs cryogéniques. Nous étudions les niveaux de bruit de ces stations sur un large spectre de fréquences allant des modes propres sismiques longue période jusqu'aux marées. Nous montrons que les gravimètres supraconducteurs apportent une contribution unique à l'étude des modes de vibration les plus graves qui échantillonnent la Terre de la surface jusqu'au noyau. Nous mettons en avant (1) l'éclatement dû à la rotation et à l'ellipticité du mode propre 0S2 en cinq singlets, (2) la première observation du mode sismique 2S1, après le séisme du Pérou du 23 juin 2001 de magnitude 8.4.Nous nous consacrons à la recherche du mode propre de translation de la graine 1S1 qui n'a jamais été observé sans ambiguïté. Sa détection est primordiale car elle permettrait de contraindre le saut de densité à l'interface graine - noyau liquide, ainsi que la viscosité à cette interface et la stratification du noyau fluide. Pour cela nous développons des méthodes de sommation, de détection automatique des signaux et une famille d'ondelettes.
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Guignard, Stéphan. "Suivi d'interface de type V. O. F. : application au déferlement des ondes de gravité dû aux variations bathymétriques." Toulon, 2001. http://www.theses.fr/2001TOUL0017.
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Ces deux dernières décades, les thématiques industrielles et académiques ont vu fortement augmenter les besoins en simulation numérique d'écoulements incompressibles multîfluides de fluides visqueux. Ce mémoire présente une étude effectuée dans le cadre d'une thèse de docteur-ingénieur CNRS/Entreprise dont la dominante est le développement d'une méthode de suivi d'interface de type volume de fluide (V. O. F) et son intégration dans un code industriel de mécanique des fluides afin d'en améliorer les performances en simulation d'écoulement multifluides. Cette méthode originale de suivi d'interface intitulée SL-VOF (Segment Lagrangian - Volume Of Fluid), utilise une représentation affine par morceau de l'interface et un schéma Lagrangien de son advcction. Les différentes versions sont testées tout d'abord sur des cas cinématiqucs simples et il apparaît que la dernière est d'ordre 2. Des simulations 2DV du déferlement d'une onde solitaire provoqué par une diminution spatiale progressive (plage) ou brutale (ouvrage de protection immergé ou émergé) de la hauteur d'eau sont validées de deux manières: Jusqu'au point de déferlement les caractéristiques de i'onde simulée (célérité, hauteur de crête, déformée de la surface libre) sont comparées avec succès à celles de l'onde solitaire simulée par une méthode intégrale aux frontières. Apres le point de déferlement, une comparaison satisfaisantes de la déformée de l'interface avec des expériences de laboratoire réalisées dans le cadre de ce travail achève de valider le modèle développé. Les simulations couvrent aussi le phénomène de splash-up et le début du run-up. Les temps de calcul très élevés ont conduii au développement d'une méthode de couplage entre le modèle présente et une méthode potentielle intégrale aux frontières. L'application de ce couplage à la simulation du déferlement d'une onde solitaire sur une plage en pente a permis de réduire le temps de calcul d'un facteur 7 et une comparaison avec des données expérimentales valide ce développementThose two last decades, both in the industrial and academics fields, the needs in numerical simulation of multi-fluid flows involving viscous fluids have strongly increased. This thesis presents a study performed in the frame of a "CNRS/SME" granted Ph-D which major input is the development of an high order interface tracking method based on the Volume Of Fluid concept (V. O. F) and it integration in an industrial CFD code in order to improve it's capabilities in numerical simulation of multifluid flows. This original interface tracking method called SL-VOF (Segment Lagrangian - Volume Of Fluid) uses a piecewise linear interface representation and a lagrangian advection scheme. Various versions of this method arc first tested on simple kinematics cases from which the last version appears to be of fully second order. The two first versions of the method arc then tested throughout 2DV numerical simulations of solitary wave breaking due to a spatial mean water level decrease, slow (beach case) or quick (artificial reef, dike). Two kind of comparisons are then considered:From the initial condition to the breaking point, the characteristics (celerity, crest height, free surface shape) of the wave simulated without the air-water effect are successfully compared with those of the wave simulated with a high order B. L. E. M method. After the breaking point, the air-water interaction throughout the interface is considered with respect to the real density ratio and good comparisons for the interface shape evolution until the splash-up phenomena with experiments conducted in the frame of this study achieve the validation of our method. The beginning of the run-up is although computed. High CPU time have motivated the development of a coupling algorithm with a B. I. E. M. . An application of the coupling to the solitary wave breaking on a sloping beach have shown a computational time divided by a ratio of seven. Moreover, these faster computations compare satisfactorily with experimental data on the wave height
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Rosat, Séverine. "Variations temporelles de la gravité en relation avec la dynamique interne de la Terre : Apports des gravimètres supraconducteurs." Université Louis Pasteur (Strasbourg) (1971-2008), 2004. https://publication-theses.unistra.fr/public/theses_doctorat/2004/ROSAT_Severine_2004.pdf.
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La dynamique et la structure interne de la Terre sont mal contraintes en profondeur, car les signaux induits en surface, de faible amplitude et basse fréquence, atteignent le seuil de détection des sismomètres. La gravimétrie devient un outil privilégié d'investigation de la Terre profonde aux longues périodes. Les variations temporelles de la gravité sont enregistrées en permanence par des gravimètres relatifs cryogéniques. Nous étudions les niveaux de bruit de ces stations sur un large spectre de fréquences allant des modes propres sismiques longue période jusqu'aux marées. Nous montrons que les gravimètres supraconducteurs apportent une contribution unique à l'étude des modes de vibration les plus graves qui échantillonnent la Terre de la surface jusqu'au noyau. Nous mettons en avant (1) l'éclatement dû à la rotation et à l'ellipticité du mode propre 0S2 en cinq singlets, (2) la première observation du mode sismique 2S1, après le séisme du Pérou du 23 juin 2001 de magnitude 8. 4. Nous nous consacrons à la recherche du mode propre de translation de la graine 1S1 qui n'a jamais été observé sans ambiguïté. Sa détection est primordiale car elle permettrait de contraindre le saut de densité à l'interface graine - noyau liquide, ainsi que la viscosité à cette interface et la stratification du noyau fluide. Pour cela nous développons des méthodes de sommation, de détection automatique des signaux et une famille d'ondelettesThe Earth's dynamics and interior structure are badly constrained, particularly in the deep interior, because the surface induced signals are of weak amplitude and low frequency and reach the detection level of seismometers. Gravimetry is then a privileged tool to investigate the Earth's interior at these long periods. Time varying gravity is permanently recorded at the surface by a worldwide network of cryogenic relative gravimeters. We study the noise levels of all these gravimetric stations over a wide frequency range, from the long period seismic normal modes to the tides. We show that superconducting gravimeters can uniquely contribute to the study of the low frequency Earth's vibrations, which sample the Earth from the surface to the core. We highlight (1) the splitting due to rotation and ellipticity of the 0S2 normal mode into five singlets, (2) the first observation of the 2S1 seismic mode, after the 2001, June 23rd Peru earthquake with a magnitude 8. 4. We search for the normal mode of translation of the inner core, which has never been clearly observed. Its detection is essential as it would constrain the density jump at the inner core boundary, probably also the viscosity and the outer core stratification. For that purpose, we develop some stacking, automatic detection of signals methods and a wavelet representation
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Cavalier, Mélanie. "Impact de la gravité sur la constitution du compartiment endolymphatique et conséquences de ses variations sur les mécanismes de sécrétion de l'endolymphe chez le mammifère." Montpellier 2, 2009. http://www.theses.fr/2009MON20116.
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Le mal de l'espace se caractérise principalement par l'apparition de vertiges qui persistent plusieurs jours, lors des phases de transition entre la normogravité (1G) et la microgravité. L'étiologie de ce syndrome n'est toujours pas déterminée à ce jour. Nous avons donc mis en place un paradigme expérimental pour tester si des variations de [K+] de l'endolymphe peuvent être à l'origine de ce syndrome. Ce liquide de l'oreille interne baigne le vestibule et possède une richesse en K+ particulière qui constitue le moteur électrochimique du processus de traduction des informations de déplacement en message électrique. La stabilité de la [K+] est donc essentielle au bon codage du mouvement. Pour tester ces hypothèses, nous avons soumis des rats à des modifications de gravité par passage de 1 à 2G pendant des durées variables à l'aide d'une centrifugeuse terrestre. Nous avons constaté l'apparition de désordres vestibulaires transitoires en utilisant des tests comportementaux de la fonction vestibulaire. Nous avons développé en parallèle des modèles expérimentaux in vitro (cultures organotypiques d'utricules) et in vivo (implantation chirurgicale d'électrode à sélectivité ionique dans l'utricule) afin d'évaluer les conséquences des variations de gravité sur la [K+] endolymphatique. Nous avons démontré que ces mêmes conditions de stimulation provoquent des altérations de la [K+] endolymphatique ainsi que lors du passage NG/µG sur cultures organotypiques d'utricules à l'aide du Rotary Cell Culture System (RCCS). D'après ces observations, nous postulons pour une relation de causalité entre stimulations cinétogènes et altération de l'homéostasie ionique de l'endolympheSpace Motion Sickness (SMS) is the most clinically significant phenomenon occurring during the first few days of space flight. The usual symptoms include nausea and vertigo. Little is known about the cellular mechanisms that underlie this sickness. Endolymph in the inner ear fills the sensory vestibular organs. It's an unusual extracellular fluid in that its composition is reminiscent of cerebrospinal fluid. K+ provides the major charge carrier for sensory transduction and is ideal in this function, since it is by far the most abundant ion in the endolymph. We developed an experimental paradigm to test if variations of endolymphatic ionic concentration are linked to SMS. To investigate this question, we first placed adult rats under hypergravity conditions (2g) during variable periods in a terrestrial centrifuge. Using a behavioural test battery, animals exposed to hypergravity develop a transient syndrome of vestibular behaviour abnormalities. We then developed experimental models in vitro (three-dimensional culture of mice utricle) and in vivo (selective K+ microelectrode chirurgical implantation in the rat vestibule) to evaluate the effects of gravity modification on the endolymphatic K+ concentration and potential. Our results show alterations in endolymphatic [K+] in each condition. We also investigated the effect of microgravity on utricular culture using Rotary Cell Culture System (RCCS). We then applied for a relation between cinetogen stimulations and alteration of endolymphatic ionic homeostasis
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Abou, Khalil Lara. "Study of the influence of external fields on solidification microstructures formation by X-ray radiography." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0005/document.
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La radiographie X, synchrotron et avec une source de laboratoire, a été appliquée pour étudier des phénomènes en relation avec la solidification directionnelle d’alliages Al-Cu sous champs externes et dépendants du temps. La formation des microstructures de solidification a été analysée durant des campagnes des vols paraboliques dans le cadre du projet XRMON. Nous avons montré que les variations du niveau de gravité modifiait la couche solutale, et donc la surfusion du liquide devant l’interface solide/liquide. En particulier, l’accélération du niveau de gravité induit une transition Colonnaire-Equiaxe pour un alliage affiné. Pour un alliage non-affiné, la vitesse de croissance des dendrites varie suivant les variations du niveau de gravité durant chaque parabole. Le second volet de ma thèse concerne l'effet d'un champ magnétique permanent sur la solidification équiaxe dans un gradient de température. Nous avons établi que le couplage entre le champ magnétique et le gradient de température génère une force Thermo-Electro-Magnétique qui modifie la trajectoire des grains équiaxes au cours de leur sédimentation. L’action de cette force est bien décrite par le modèle analytique de Wang et al., moyennant des corrections associées au confinement et à la morphologie des grains. Certains effets du champ magnétique sur le liquide ont été également révélésX-ray radiography with synchrotron and laboratory source was applied to study phenomena related to the directional solidification of Al-Cu alloys under external fields and time-dependent. The solidification microstructures formation has been analyzed during parabolic flight campaigns in the framework of XRMON project. We have shown that the gravity level variations modified the solutal layer and then the liquid undercooling ahead of the solid/liquid interface. In particular, the acceleration of gravity level induces the Columnar-to-Equiaxed transition in a refined alloy. For a non-refined alloy, the dendrite growth velocity changes with respect to the gravity level variations during each parabola. The second part of this thesis relates to the effect of a permanent magnetic field on the equiaxed solidification in a temperature gradient. The coupling between the magnetic field and the temperature gradient generates a Thermo-Electro-Magnetic force that modifies the equiaxed grains trajectory during their sedimentation. The action of this force is well described by an analytical model proposed by Wang et al. with additional corrections associated to the wall confinement and the grain morphology. Effects of the magnetic field on the liquid have been also revealed
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Métivier, Laurent. "Influence des variations latérales de densité et de paramètres rhéologiques sur la déformation de la terre." Paris 7, 2004. http://www.theses.fr/2004PA077237.
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A l'heure du développement de la gravimétrie spatiale (satellites GRACE et GOCE), de nouveaux modèles de déformation gravito-élastique de la Terre deviennent indispensables. La Terre se déforme en chaque instant sous l'action de la Lune et du Soleil (la marée luni-solaire), et sous l'action des surcharges de surface engendrées par les enveloppes fluides de la planète (l'atmosphère, les océans et les eaux continentales). Actuellement, ces déformations élastiques sont modélisées en supposant la Terre comme un solide sphérique (ou ellipsoïdale) dont la structure interne est hydrostatique et à symétrie radiale. Or, la planète contient des variations latérales de densité et de paramètres rhéologiques, engendrées par sa dynamique interne, qui sont négligées dans ces modèles. Nous avons réalisé un nouveau modèle de déformation de la planète qui, pour la première fois, tient compte des variations latérales internes des paramètres physiques de la Terre, de son état de précontraintes non-hydrostatique et de ses topographies dynamiques aux interfaces de discontinuités. Ces aspects sont intégrés dans les équations de la gravito-élasticité utilisant la théorie des perturbations. Le système d'équations est résolu à l'aide d'une méthode numérique : les éléments spectraux associés au maillage de la "sphère cubique". Le modèle a été validé avec une bonne précision sur des problèmes géodynamiques connus. Nous avons dans ce but repris les travaux analytiques réalisés par Love concernant une Terre homogène incompressible. Nous nous consacrons ensuite à de premières applications. Nous réévaluons l'impact de l'ellipticité de la Terre sur sa réponse de marée solide, et sur sa réponse aux surcharges de surface. Nous prenons l'exemple de la surcharge de pression atmosphérique et son influence sur les variations zonales de la gravité (les coefficients J2 et J3). Enfin nous discutons des applications de ce modèle à la détermination de l'influence des méga-panaches mantelliques sur la réponse de marée et la réponse de surcharges de la TerreNowadays with the development of space gravimetry (GRACE and GOCE satellites), new elasto-gravity deformation models become essential. Earth is continuously deformed by the Sun and the Moon attraction (luni-solar tides), and under the action of surface loading due to external fluid layers (atmosphere, ocean and continental water). Presently these elastic deformations are modelized assuming that the Earth is a spherical solid (or ellipsoïdal) with a radially symmetrical hydrostatic structure. However, the internal dynamic of the planet induces lateral variations of density and rheological parameters that are neglected into these models. We built an Earth deformation model which, for the first time, takes into account the internal lateral variations of the planet physical parameters, its no-hydrostatic prestresses, and the dynamical topographies of its discontinuity interfaces. These particularities are integrated into the elasto-gravitational equations using the perturbation theory. The equation System is solved with a numerical method: the spectral element method associated to the "cubed sphere" mesh. The model has been validated on known geophysical problems with a good accuracy. With this aim, we recovered the Love analytical work concerning a homogeneous incompressible Earth. We then made first applications. We appraised the impact of Earth ellipticity on solid tides and on the Earth response to surface loadings. We took the example of the influence of atmospheric pressure on zonal gravity variations (J2 and J3 coefficients). Finally, we discuss the ability of the model to determine the influence of mantellic superplumes on the tidal response and the loading response of the Earth
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Nyberg, Sofia. "EGG BUOYANCY AND SURVIVAL PROBABILITIES OF BALTIC FLOUNDER (PLATICHTHYS FLESUS) : DIFFERENCES BETWEEN SPAWNING AREAS AND INTER-ANNUAL VARIATION IN CONDITIONS FOR REPRODUCTION." Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-305655.
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The reproductive success for pelagic spawning Baltic flounders is strongly linked to the hydrodynamics in the spawning areas. Egg survival is dependent upon the ability to achieve neutral buoyancy at a depth interval where temperature and oxygen concentrations are favourable for egg development. The main focus of this thesis was to compare egg survival probabilities of pelagic eggs from Baltic flounder in the Bornholm, Gdansk and Gotland basins, prior to and after the saline water inflow in December 2014. The results showed greatly enhanced survival probabilities in Bornholm basin 2015 (p<0.01), as egg survival increased from 47% in 2014 to 100% the following year. In Gdansk basin the situation was similar, and survival probability increased from 13% to 100% (p<0.01). In Gotland basin no difference in survival probability was identified, although the dominant cause of mortality shifted from sedimentation, i.e. due to low salinity conditions in 2014, to oxygen deficiency in 2015 (p<0,01).BONUS INSPIRE-project, the joint Baltic Sea research and development programme (Art 185), funded jointly by the European Union’s Seventh Programme for research, technological development and demonstration and the Swedish Research Council Formas
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Maurice, Michel. "Participation à la construction d'un spectromètre RMN in vivo : application à la mesure des variations de volume de l'eau au niveau du vertex chez l'homme en microgravité simulée." Lyon 1, 1991. http://www.theses.fr/1991LYO1T009.
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Vaz, De Almeida Flavio-Guilherm. "Etudes des variations temporelles du champ de pesanteur terrestre à partir des données de la mission GRACE : application au bassin amazonien." Toulouse 3, 2009. http://thesesups.ups-tlse.fr/583/.
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L'objectif de ce travail est d'analyser les variations temporelles du champ de gravité, déterminées par la mission spatiale Gravity Recovery and Climate Experiment (GRACE), et ses relations avec la dynamique des eaux dans la région Amazonienne. À ce titre, nous avons cherché à développer une méthodologie pour les estimations des stocks d'eau dans des zones innondables non contrôlées ou difficilement accessibles. Pour ce faire, les coefficients de Stokes, calculés par le Groupe de Recherche de Geodesie Spatiale (GRGS) de Toulouse, ont été convertis en hauteur d'eau équivalente (HEE, Equivalent water Height - EWH en anglais) sur une période d'environ 4 ans (juillet de 2002 à mai 2006). Les valeurs d'HEE ainsi obtenues ont été comparées aux niveaux d'eau in-situ collectés par l'Agence Nationale de lEau brésilienne (ANA). Le choix du bassin Amazonien pour ce travail tient au fait qu'il présente en son centre, des amplitudes d'environ 1250mm de HEE, soit les plus grandes du monde. Cette amplitude est validée indirectement par comparaison entre les déplacements crustaux verticaux équivalents à cette charge superficielle et les mouvements verticaux de la stations GPS permanente de Manaus, à proximité du centre du bassin. Nous estimons que les erreurs associées à ces HEE sont au maximum de l'ordre de ~160mm HEE. Elles proviennent des erreurs des coefficients de Stokes, de la troncation du spectre et des erreurs de contamination (leakage) d'informations hydrologiques des bassins voisins. Finalement, HEE et les données de hauteur d'eau sont comparées dans les fleuves en terme d'hydrogéologieThe objective of this work is to analyze the temporal variations of the gravitational field, determined by the space mission Gravity Recovery and Climate Experiment (GRACE), and its relationships to the dynamics of water in the Amazon basin area. For this reason, was developed a methodology to estimate the water level in not controlled stocks or difficult to reach floodplains. With this intention, the Stokes coefficients, calculated by the Groupe de Recherche de Geodesie Spatiale (GRGS) Toulouse-FR, were converted into equivalent water height (EWH) for a ~4-year period (July-2002 to May-2006). In this basin, the amplitudes of EWH signal are the largest on Earth and can reach about 1250mm at the center of the basin. Analysis of the uncertainties indicate that it represents ~160 mm of EWH in this basin, including Stokes coefficient uncertainties (~130 mm), leakage errors (12 ~ 21 mm) and spectrum truncation (10 ~ 15 mm). This amplitude was indirectly validated by the comparison between equivalent vertical crustal displacements due to surface water load and the vertical movements of the Manaus GPS permanent monitoring stations, near to the center of the basin. The values of EWH thus obtained were compared with the in-situ water level collected by the Brazilian National Agency of Water (ANA) at 233 ground-based hydrometric stations (HS). Although EWH and HS measure different water bodies, high correlation, up to ~80% in most of the cases, is detected. This high correlation allows adjusting linear relationships between both series for the major tributaries of the Amazon. The regression coefficients decrease from upstream to downstream along the rivers reaching the theoretical value 1 at the mouth of the Amazon in the Atlantic Ocean
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Beaumont, Maurice. "Effets sur la mécanique ventilatoire et les voies aériennes supérieures des variations de la gravité terrestre et d'une méthode de ventilation en pression positive continue utilisée en protection contre les effets des accélérations +Gz." Paris 12, 1997. http://www.theses.fr/1997PA120085.
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Le but de ce travail etait de montrer les effets d'une contrepression thoracique (ct) et abdominale (ca) sur les perturbations de la mecanique ventilatoire et de l'activite des muscles respiratoires liees a une methode de ventilation en pression positive (ppb) utilisee en protection contre les effets hemodynamiques des accelerations +gz. Une etude prealable realisee au banc dans des conditions statiques et dynamiques montre que le systeme generateur de pression utilise impose un travail inspiratoire additionnel, fonction du niveau de ppb ou de debit instantane. Les deux autres experimentations montrent que le volume pulmonaire n'augmente pas quand tcp et acp sont associees a la ppb et que les effets hemodynamiques et respiratoires observes sous 40 hpa de ppb (hyperventilation, expansion pulmonaire, activite musculaire expiratoire importante, abolition de l'activite diaphragmatique et tachycardie) sont limites efficacement par l'utilisation de ct et ca, qui exercent des effets additifs. A ces effets, s'ajoutent les consequences hemodynamiques de la ppb associee a ct et ca : la pression arterielle augmente avec le niveau de ppb, ce qui complete la protection contre les effets physiologiques des accelerations apportee par le pantalon anti-g. Enfin, les effets sur les voies aeriennes superieures (vas) des variations de la gravite terrestre observees au cours de vols paraboliques ont ete analyses par une methode de reflexion acoustique. Le diametre des vas augmente avec le niveau de gravite en position assise, sauf au niveau larynge. Ces variations sont en rapport avec une augmentation de la capacite residuelle fonctionnelle et avec une diminution du volume sanguin lingual. En position couchee, la surface laryngee diminue avec l'augmentation de la gravite, non pas en raison d'une variation des volumes pulmonaires mais plutot en raison d'un effet mecanique direct de la gravite.
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Kiamehr, Ramin. "Precise Gravimetric Geoid Model for Iran Based on GRACE and SRTM Data and the Least-Squares Modification of Stokes’ Formula : with Some Geodynamic Interpretations." Doctoral thesis, KTH, Transporter och samhällsekonomi (stängd 20110301), 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4125.
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Iran is one of the most complicated areas in the world from the view of rough topography, tectonic activity, large lateral density and geoidal height variations. The computation of a regional gravimetric geoid model with high accuracy in mountainous regions, especially with sparse data, is a difficult task that needs a special attention to obtain reliable results which can meet the needs of the today geodetic community. In this research different heterogeneous data has been used, which includes gravity anomalies, the high-resolution SRTM Digital Elevation Model (DEM), recently published GRACE Global Geopotential Models (GGMs), geological maps and GPS/levelling data. The above data has been optimally combined through the least-squares modification of Stokes formula with additive corrections. Regarding the data evaluation and refinement, the cross-validation technique has been used for detection of outliers. Also, several GGMs and DEMs are evaluated with GPS/levelling data. The impact of utilizing a high resolution SRTM DEM to improve the accuracy of the geoid model has been studied. Also, a density variation model has been established, and its effect on the accuracy of the geoid was investigated. Thereafter a new height datum for Iran was established based on the corrective surface idea. Finally, it was found that there is a significant correlation between the lateral geoid slope and the tectonic activities in Iran. We show that our hybrid gravimetric geoid model IRG04 agrees considerably better with GPS/levelling than any of the other recent local geoid models in the area. Its RMS fit with GPS/levelling is 27 cm and 3.8 ppm in the absolute and relative senses, respectively. Moreover, the relative accuracy of the IRG04 geoid model is at least 4 times better than any of the previously published global and regional geoid models in the area. Also, the RMS fit of the combined surface model (IRG04C) versus independent precise GPS/levelling is almost 4 times better compared to the original gravimetric geoid model (IRG04). These achievements clearly show the effect of the new gravity database and the SRTM data for the regional geoid determination in Iran based on the least-squares modification of Stokes’ formula.QC 20100906
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Guignandon, Alain. "Contribution à l'étude de la relation structure - fonction de cellules ostéoblastiques ROS 17/2. 8 soumises à des variations du vecteur gravité : approche quantitative de l'adhésion focale et relation avec le cycle cellulaire." Saint-Etienne, 1997. http://www.theses.fr/1997STET4005.
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Les cellules ostéosarcomateuses ROS 17/2. 8 présentent les caractères d'ostéoblastes différenciés et sont sensibles à un stress mécanique. Les forces mécaniques peuvent être transmises à la cellule par le biais de la matrice extracellulaire. Les zones de contact (adhésion focale) qui assurent un continuum entre le cytosquelette et la matrice extracellulaire sont constituées d'un assemblage d'intégrines et de protéines du cytosquelette (actine, taline, vinculine, paxilline, -actinine). Nous avons étudié l'adhésion cellulaire des cellules ROS 17/2. 8 soumises à des variations du vecteur g. Lors de vols paraboliques, les cellules subissent une succession de 30 paraboles (variation de 0 g à 2 g). La succession des variations de g nous a conduit à définir des expériences contrôlées à 2 g constant par centrifugation et à 0 g constant dans un clinostat rapide qui produit une microgravité simulée. Dans le clinostat, la direction du vecteur g change constamment induisant un leurre gravitationnel pour les cellules en rotation. Nous avons utilisé ou développé un certain nombre de techniques : adaptation des cultures cellulaires à l'environnement spatial, test d'adhésion cellulaire, dosages biochimiques dont les pge#2 l'immunofluorescence et l'analyse d'images (en collaboration avec Y. Usson - Dyogen). Les programmes d'analyse d'images développés ont permis de quantifier l'adhésion focale par l'immunofluorescence de protéines cytosquelettiques, en particulier la vinculine qui colocalise aux contacts focaux (microscopie confocale) et par microscopie de réflexion (IRM) révelant l'interface cellule-matrice. Aucun des niveaux constants de contrainte n'entraine de modification de l'adhésion focale ni de la morphologie de la cellule. En revanche, l'adaptation dynamique au stress mécanique du vol parabolique se fait par l'établissement de nouveaux contacts focaux (augmentation de l'IRM) ne dépendant pas de la vinculine. Nous avons observé, aussi bien en vol spatial que parabolique, une hétérogénéité dans la réponse des ROS 17/2. 8 pourtant clonales. Cette hétérogénéité, nous a conduit à évaluer le rôle du cycle cellulaire dans la réponse à la diminution des contraintes mécaniques. Nous avons montré que la progression dans le cycle (g1 vers m), s'accompagne d'une importante rétraction cellulaire associée à une diminution et une redistribution des contacts focaux, sans modification de la surface relative de ces contacts. Lors de la clinorotation (24 hr), la progression dans le cycle est effective mais seules les cellules quiescentes réorganisent leurs contacts focaux. La phase du cycle est donc un élément déterminant dans la dynamique des plaques d'adhésion qui doit être pris en compte dans l'étude des effets des contraintes mécaniques sur les cellules ostéoblastiques
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Granet, Corinne. "Mécanismes d'adaptation de cellules ostéoblastiques Ros17/2. 8 aux variations des contraintes mécaniques dans des modèles de micro-gravité simulée et de déformation du support de culture : implication des facteurs de transcription : AP-1, Egr-1, NF-kB." Saint-Etienne, 2000. http://www.theses.fr/2000STET006T.
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De, Linage Caroline. "Mesures gravimétriques au sol et satellitaires: étude du rapport entre variation de pesanteur et déplacement vertical et apport de la mission spatiale GRACE à l'étude des surcharges hydrologiques et des très grands séismes." Phd thesis, Université Louis Pasteur - Strasbourg I, 2008. http://tel.archives-ouvertes.fr/tel-00349160.
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Nous modélisons le rapport entre variation de pesanteur et déplacement vertical du sol dus à une surcharge à la surface d'un modèle de Terre à symétrie sphérique, stratifié et élastique. Les résultats théoriques sont comparés aux valeurs numériques trouvées pour diverses charges à partir des sorties de modèles globaux. Nous évaluons la résolution et la précision des variations temporelles du contenu en eau du sol estimées par la mission de gravimétrie spatiale GRACE. Celles-ci sont comparées aux prédictions des variations saisonnières de plusieurs modèles hydrologiques. En Europe, la validation des mesures GRACE par les mesures des gravimètres du reseau GGP repose sur une analyse en composantes principales et met en évidence la sécheresse de l'été 2003. Les signatures gravitationnelles cosismique et postsismique associées au séisme de Sumatra (2004) sont extraites des données GRACE. Une modélisation de l'effet cosismique montre que la réponse statique de l'océan ne peut être negligée.
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Werth, Susanna [Verfasser]. "Calibration of the global hydrological model WGHM with water mass variations from GRACE gravity data / Susanna Werth." 2010. http://d-nb.info/1002803667/34.
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Elsaka, Basem [Verfasser]. "Simulated satellite formation flights for detecting the temporal variations of the Earth's gravity field / von Basem Abd Elkareem Anwar Elsaka." 2010. http://d-nb.info/1007226625/34.
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Roach, Lisa Aretha Nyala. "Temporal Variations in the Compliance of Gas Hydrate Formations." Thesis, 2012. http://hdl.handle.net/1807/44081.
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Seafloor compliance is a non-intrusive geophysical method sensitive to the shear modulus of the sediments below the seafloor. A compliance analysis requires the computation of the frequency dependent transfer function between the vertical stress, produced at the seafloor by the ultra low frequency passive source-infra-gravity waves, and the resulting displacement, related to velocity through the frequency. The displacement of the ocean floor is dependent on the elastic structure of the sediments and the compliance function is tuned to different depths, i.e., a change in the elastic parameters at a given depth is sensed by the compliance function at a particular frequency. In a gas hydrate system, the magnitude of the stiffness is a measure of the quantity of gas hydrates present. Gas hydrates contain immense stores of greenhouse gases making them relevant to climate change science, and represent an important potential alternative source of energy. Bullseye Vent is a gas hydrate system located in an area that has been intensively studied for over 2 decades and research results suggest that this system is evolving over time.
A partnership with NEPTUNE Canada allowed for the investigation of this possible evolution. This thesis describes a compliance experiment configured for NEPTUNE Canada’s seafloor observatory and its failure. It also describes the use of 203 days of simultaneously logged pressure and velocity time-series data, measured by a Scripps differential pressure gauge, and a Güralp CMG-1T broadband seismometer on NEPTUNE Canada’s seismic station, respectively, to evaluate variations in sediment stiffness near Bullseye. The evaluation resulted in a (- 4.49 x10-3± 3.52 x 10-3) % change of the transfer function of 3rd October, 2010 and represents a 2.88% decrease in the stiffness of the sediments over the period. This thesis also outlines a new algorithm for calculating the static compliance of isotropic layered sediments.
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Cheng, Kuei-Jen, and 程貴仁. "Evaluation of the Variation in Dynamic Performance and Service Life of a Manipulator after being Gravity Balanced." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/38826032517157838685.
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博士國立交通大學
機械工程學系
99
Manipulators have widely been utilized in industrial field to do assembly jobs in production lines. There are many different types of manipulators have been deployed for different applications, but most of them have a common characteristic, and that is the payload of a manipulator is much smaller than its self-weight. This is because a manipulator needs stiff structure to prevent from the excessive deformation resulted from the objects it holds to keep the positioning accuracy. However, the stiff structure results in the increase of the self-weigh and consumes considerable the output of the actuators of the manipulator. This not only increases the energy being consumed but also decreases the dynamic performance of the manipulator. The dynamic performance of a manipulator is usually presented by acceleration radius. Acceleration radius is an index which is used to measure of the acceleration capacity of a manipulator with a certain configuration and at a specific posture. Dynamic performance will be influenced by the configuration, the posture, and the output capacity of the constituent joint actuators of the manipulator under discussion. When it is represented by acceleration radius, it means that the maximum acceleration which the end of a manipulator with certain configuration can achieve in all directions at that specific posture. Conventionally, there are two approaches can be used to increase the dynamic performance of a manipulator, and they are: 1. raising the output limits of the actuators it uses; 2. reducing the weight of the manipulator system. Raising the output limits of the actuators means that more energy needs to be exerted or/and the specification of the actuators needs to be promoted. However, raising the output limits of the actuators would result in cost increase, and exerting more energy will increase the cost and reduce the derating rate. Lowering derating rate usually results in the decline of the designed service life. Reducing the weight of a manipulator system usually can be achieved by using better and stiffer materials or complicated but stiffer structures, or reducing the materials it uses. Using better materials and structure means the increase in the fabrication cost. Reducing the materials in use means the stiffness of the system decreases, and this will result in the deterioration in positioning accuracy which is caused by the increase of the compliance of the system. Based on what is stated above, these two conventional approaches used to promote the dynamic performance of a manipulator are not suitable to be implemented in real cases. In most applications, the output of actuators of a manipulator spends on counterbalancing the gravitational force resulted from the stiff but heavy structure, not on accelerating the object it holds. To redeem this insufficiency, this study utilizes auxiliary mechanisms which is designed based on gravity balance theory to eliminate the influence of the self-weight of a manipulator and the mechanism. However, the auxiliary mechanism can eliminate the influence of self-weight but also changes the configuration of the original manipulator. This change may affect the dynamic performance and the service life of the manipulator. To cope with this issue, this study utilizes maneuverability ratio to evaluate the influence of an auxiliary mechanism on the dynamic performance of a manipulator after being equipped with that mechanism. Besides, this study also utilizes deterioration rate to investigate the deterioration in dynamic performance of a manipulator with the errors resulted from the operation and evaluate the influence on the designed service life. This study provides an effective methodology to evaluate the influence of a gravity balance mechanism on the dynamic performance and the designed service life of a manipulator. With the help of proposed methodology, designers of manipulators can not only have the ability to find out the relationship among the energy efficiency, performance, and designed service life of a manipulator but also have the capability to choose the best design to match the prescribed service conditions based on the results of evaluation.
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Razeghi, Seyedeh Mahdiyeh. "Surface mass variation on the solid earth inferred from GPS deformation time series and GRACE gravity field measurements." Thesis, 2020. http://hdl.handle.net/1959.13/1412540.
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Research Doctorate - Doctor of Philosophy (PhD)Deformation time series from GPS and gravity field change observations by the GRACE satellite mission, used either as validation or in combination, have been deployed to quantify the Earth’s elastic and viscous responses to different kinds of surface mass loading. These two data sets can complement each other to study the surface mass variations, when they are made consistent in terms of spatial resolution, temporal resolution and their reference frames. This study explored the Slepian localization method to make two distinct geodetic data sets consistent in terms of spatial and spectral resolutions. This method also made it possible to determine regional surface mass change in Australia merely by GPS deformation data. The monthly surface mass variation not only agreed with other independent datasets, such as GRACE, the atmospheric model, and the hydrology model, but also presented significant sub-monthly changes throughout the area of the study. In terms of the reference frame, a new technique was developed to co-estimate geocentre motion and the gravitational potential field from global observations of the GPS and GRACE. Geocentre motions resulting from this new approach were mostly consistent with the SLR degree-1 solutions indicating an overall seasonal migration pattern from Europe to the South Pacific Ocean of the degree-1 surface mass load. In addition to estimating the Earth’s elastic responses, these two geodetic data sets can also be employed for estimating the Earth’s viscous responses, which are associated to GIA. A high-resolution ice mass model of the Totten Glacier’s outlet was constructed, which follows altimetry measurements in terms of spatial resolution, and GRACE gravity data in terms of temporal resolution, to calculate the elastic deformation over the area. The GIA uplift rate was computed by removing anticipated elastic responses from the GPS vertical time series, and then the residual deformation was considered to be the viscos deformation and compared to various GIA models. It is also found that removal of the predicted elastic deformation from the east and north components of GPS tie series resulted in a steady-state trend relevant to kinematic plate motions.
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Wang, Cheng-Gi, and 王成機. "Determinations of the Earth's gravity field and its temporal variation from satellite tracking data: case studies for CHAMP and GRACE missions." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/81510444604262529305.
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博士國立交通大學
土木工程系所
93
With the advent of the CHAMP and GRACE satellite missions, satellite gravimetry has opened a new era featuring high spatial resolution and accuracy. These two missions provide continuous satellite tracking data in a high-low（HL-SST） and a low-low satellite-to-satellite tracking（LL-SST） scenario. They are both equipped with accelerometers for determining non-gravitational forces and star-cameras for determining attitudes. For each mission a laser retro-reflector is also mounted to provide additional tracking data. The GRACE mission uses a K-band ranging system to determine ranges and range rates (RR) between the two GRACE satellites at an accuracy of 10 m and 1 m/s, respectively. Precise range-rate rates (RRR) can be derived from RR. The uniqueness and the unprecedented accuracy of CHAMP and GRACE's tracking data have motivated this study, which mainly focuses on methods for efficiently recovering the Earth's gravity field and its temporal variation. A phase method is developed. In this method, GPS phase observations of a low earth orbiter (LEO) are used to compute line-of-sight accelerations between GPS and LEO, which are then used to determine the 3-dimensional accelerations of LEO using precise GPS ephemeris. Accelerations are linear functions of gravity coefficients, which make the least-squares estimation of gravity coefficients very simple in terms of computational effort. This method is efficient and does not require modeling GPS integer ambiguities. However, accelerations other than the Earth's gravity-induced acceleration must be modeled and removed from the phase-determined accelerations. The gravity coefficients recovered from CHAMP by this method agree well with the EGM96 gravity coefficients. Closed, linear expressions between RR or RRR and gravity coefficients are established using a linear orbit perturbation theory. These expressions are based on the concepts that RR is a function of the potential difference between two satellites and RRR is the line-of-sight acceleration. These expressions are used in a least-squares estimation of gravity coefficients from GRACE's RR or RRR. Seven days of simulated data using EGM96 and OSU91A have been used to test the theories and computer programs based on these expressions. A direct acceleration method is employed to determine the time variation of the Earth's gravity field. In this method, the accelerations of LEO are determined by numerical differentiations of the positions of LEO. After removing accelerations other than the Earth's gravity-induced accelerations, linear relations between LEO accelerations and gravity coefficients can be established, as in the phase method. Empirical parameters can be used to model the residual non-Earth-gravity accelerations. The time series of J2 derived from one year of CHAMP data and four months of GRACE data by this method closely resemble the SLR-derived time series of J2. Moreover, one set of normal equations is computed from a 7-day orbit arc. A total of 42 such normal equations from CHAMP data and 33 normal equations from GRACE data are computed. These normal equations are considered uncorrelated and are combined to determine an averaged gravity field. This gravity field yields a geoid model with an accuracy of better 5 mm at a spatial resolution of 1000 km half-wavelength, which is better than those derived from the recent satellite-only EIGEN-1S and EGM96 gravity fields.
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Wen-Chieh, Chen, and 陳文傑. "The Influence of HMA Mixture’s Sampling Variation on Quantitative Extraction of Asphalt Binder and Detection of Standard Test Body’s Bulk Specific Gravity By AC10." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/27718047220484220499.
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碩士國立金門大學
土木與工程管理學系碩士班
103
In recent years, local governments have taken the “flat road project” as a key priority of administration; meanwhile, various projects and related research programs have been promoted successively, which mainly aim to avoid safety problems caused by damaged or short-life bumpy roads. HMA is mostly utilized material in domestic road pavements for vehicles. In order to make sure that the pavement materials quality can conforms to the design criteria and further insure the asphalt concrete payment’s long-term service efficiency, the quality of asphalt concrete shall be inspected to check whether it can meets the expected requirements. The research focuses on the influence of the sampling variation of HMA with a viscosity grade of AC-10 on the test results of acceptance indexes and evaluates how it influent on the terminal test results so as to confirm whether its properties meet the requirements. Analysis of test results shows that when the coarse aggregate content of the sample is less than that of JMF, with respect to the most probable value, the asphalt content and the compaction degree increase, and the bulk specific gravity decreases; when it is greater than that of JMF, compared to the most probable value, the asphalt content and the compaction degree decrease, and the bulk specific gravity increases. The sampling variability causes the grain size of the sieved part to go beyond JMF and the test result to be nonconforming, so the constructors have to remove and remake them, which has a bad influence. Therefore, sampling and testing are equally important. People should take samples cautiously enough to make the sample represent the population as much as possible. Keywords: HMA, Sampling Variation, Asphalt Content, Bulk Specific Gravity, Compaction Degree