Le rhéoépaississement est un phénomène spectaculaire apparaissant dans certaines suspensions concentrées en particules. Il se manifeste par l’augmentation brutale de la viscosité de la suspension au delà d’une contrainte critique. L’exemple emblématique de suspension présentant ce type de comportement est le mélange d’amidon de maïs et d’eau. Le rhéoépaississement est longtemps resté une énigme, jusqu’à des travaux théoriques et numériques récents proposant un modèle microscopique cohérent. Selon celui-ci, le rhéoépaississement provient d’une transition frictionnelle due à la présence d’une force répulsive entre les grains. Au cours de ma thèse, j’ai réalisé une des premières démonstrations expérimentales directe de ce mécanisme. En m'inspirant de travaux venant du domaine des milieux granulaires, j'ai montré qu'en accord avec le modèle de transition frictionnelle, une suspension rhéoépaississante possède à faible pression granulaire un état non frottant. J'ai ensuite mis en évidence la transition en elle-même dans des suspensions contrôlées de billes de silice dans des solutions salines. Pour cela, j'ai dû développer de nouvelles méthodes de rhéologie à pression imposée. En effet, les rhéomètres standard ne permettent pas d'accéder aux propriétés de frottement des suspensions. Le seul rhéomètre qui le permet n'est pas adapté aux suspensions étudiées ici, qui sont constituées de particules colloïdales. Ce travail ouvre donc la voie au développement d’une nouvelle génération de rhéomètres permettant de mesurer le frottement dans les suspensions colloïdales, un enjeu majeur pour la rhéologie des fluides complexes. / Shear thickening is a spectacular phenomenon which takes place in some dense suspensions. It manifests itself by a brutal increase of the suspension's viscosity above a certain critical stress. The most iconic example of shear-thickening suspensions is cornstarch and water mixes. Shear thickening long remained a mystery, until recent theoretical and numerical works which proposed a consistent microscopic model. This model explains the shear thickening transition as a frictional one due to the presence of a repulsive force between the grains.During my PhD, I provided one of the first direct experimental proofs of this mechanism. Inspired by granular physics, I showed that shear-thickening suspensions possess a frictionless flowing state at low granular pressure, which is consistent with the proposed model. I then evidenced the frictional transition with controlled experiments using suspensions of silica beads in ionic solutions. To do this, I developed new rheological techniques enabling pressure imposed measurements. Indeed, standard rheological tools do not allow access to the frictional properties of suspensions. The only rheometer that does that is not adapted to the suspensions we study here, which are colloidal. This work thus paves the way for the development of a new generation of pressure imposed rheometers, giving access to colloidal suspensions friction, which is a major challenge in complex fluids rheology.

Resumo: Devido a frequente demanda por aplicações de produtos fitossanitários dada pela ocorrência simultânea de pragas (insetos, doenças e planta-daninha) em uma mesma área e a procura do agricultor em otimizar recursos financeiros e operacionais na lavoura, a prática de misturas em tanque de diferentes classes de produtos fitossanitários tem sido cotidiana. Os efeitos resultantes das misturas, relativos a fatores como às formulações, às dosagens e a interação entre os produtos a serem aplicados, estão associados a compatibilidade entre as formulações e às alterações físico-química nas caldas, que podem resultar na perda de eficácia dos produtos aplicados e ainda em efeitos tóxicos para a cultura tratada e ao ambiente. Nesse cenário, o objetivo desse trabalho foi avaliar as propriedades físico-químicas de calda inseticida e identificar primórdios de perda da estabilidade de misturas com fungicidas e adjuvantes. Os tratamentos foram constituídos da combinação do inseticida tiametoxam + lambda-cialotrina com os fungicidas fluxapiroxade + piraclostrobina e clorotalonil e adjuvantes lecitina e ácido propiônico e óleo mineral. Foram realizadas avaliações de características físico-químicas das combinações, quanto ao pH, condutividade elétrica, tensão superficial e ângulo de contato resultantes das caldas preparadas. Para a avaliação dos primórdios de perda da estabilidade estoudou-se o comportamento reológico, a viscosidade, o potencial zeta, a distribuição de tamanho de partículas disper... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Due to frequent demand for pesticide applications, imports of financial and operational resources in tillage, a practice of tank storage of different classes phytosanitary products has been daily. The effects of the mixtures are factors such as the formulations, the dosages and the interactions between the products that are applied, are associated to the compatibility between the formulations and the physical of the chemical complex in the syrups, that can cause the breakage of its products and also in toxic effects on the treated crop and the environment. In this scenario, the use of chemical-chemical syrups proved to be insidious and identitarian, impairing the stability of the mixtures with fungicides and adjuvants. The isolates were constituted by the combination of the insecticide thiamethoxam + lambda-cyhalothrin with fungicides fluxapiroxade + pyraclostrobin and chlorothalonil and lecithin and propionic and mineral acid adjuvants. The physical, chemical and enzymatic properties, such as pH, electrical conductivity, surface tension and the contact bottom of the prepared syrups were discontinued. For an evaluation of the stability results, viscosity, zeta potential, dispersion capacity and physical stability of the grouts. The combination of the thiamethoxam + lambda-cyhalothrin insecticide with the chlorothalonil fungicide and the lecithin and propionic acid adjuvants and the mineral oil interfere with the coating of the target, eliminating the surface tension of the sy... (Complete abstract click electronic access below) / Mestre

Les enjeux de santé publique et de développement durable conduisent à intensifier l’utilisation de protéines végétales notamment dans les secteurs de biens de consommation comme l’industrie pharmaceutique,l’agro-alimentaire et les cosmétiques. La levée récente de certains verrous technologique permet aujourd’hui la purification industrielle de protéines végétales issus de tourteaux provenant de la production d’huiles végétales. Ces protéines sont valorisables comme substituts aux graisses saturées dans la structuration d’huiles à destination de la consommation humaine. Le manque de texture d’huiles végétales insaturées peut être compensé par ces protéines jouant le rôle de stabilisants et de gélifiants dans les émulsions. Nous nous intéressons aux propriétés fonctionnelles des protéines de blé, de tournesol et de colza, en volume et aux interfaces. Nous avons montré que des gels de protéines de tournesol avec des élasticités modulables sont obtenus par dénaturation thermique. La dynamique de formation de films protéique aux interfaces fluides a été étudiée en combinant des mesures de tensiométrie, de viscoélasticité dilatationnelle et d’ellipsométrie. Les mesures sur plusieurs ordres de grandeurs en concentrations et en temps mettent en évidence différents régimes de structuration associés à différentes dynamiques d’adsorption pour les trois protéines de blé, de tournesol et de colza étudiées. Nous discutons également le rôle de la flexibilité des protéines dans ces différents régimes de structuration. / Challenges of public health and sustainable development trend to intensify the use of vegetables proteins, particularly in consumer goods sectors such as pharmaceutical, food and cosmetics industries. The recent overcome of technical limitation allows the industrial purification of vegetables proteins derived from meal made by vegetable oils production. These proteins are valuable as substitutes for saturated fats in structuring oils for human consumption. The lack of unsaturated vegetable oil texture can be reduced by these proteins acting as stabilizers and gelling agents in emulsions. We are interested in the functional properties of wheat, sunflower and rapeseed proteins, by volume and at interfaces. We have shown that sunflower protein gels with modulable elasticities are obtained by thermal denaturation. In addition, we studied the dynamics of protein film formation at fluid interfaces by combining measurements of tensiometry, dilatational viscoelasticity and ellipsometry. We highlight different structuring regimes and discuss the role of protein flexibility in this structuring.

This study was carried out to determine the characteristics of common carp surimi. In Australia, common carp (Cyprinus carpio) is an environmental pest, strongly coloured (dark-muscle fish), large (2-3 kg), low cost (AUD 2.5/kg) and not highly valued as it is every where else. Surimi could add value to carp, but the colour would have to be modified as surimi manufacturers prefer white coloured flesh. So, firstly the efficiency of Hydrogen peroxide (H2O2; 1-3% v/v) solution at alkaline side of pH (7.0-11.5) on whitening of light fillets of common carp was examined. The whiteness (L*-3b*) of surimi produced from treated (3% H2O2, pH 8.2) common carp light fillets was significantly (p less than 0.05) greater than that of threadfin bream surimi and was not significantly different to that of Alaska pollock. Based on a temperature sweep test, a similar pattern in G of tested surimi was observed which started at ca. 47?C and was completed at ca. 73-74?C. However, thread fin bream kamaboko showed better texture profile characteristics (hardness and gel strength) than that of the other kamaboko tested. To improve the quality of common carp surimi and kamaboko, alternative methods were applied such as modified conventional method (MCM), alkaline-aided method (AAM) and pH modified method (PMM) and the resultant surimi and kamaboko were compared with those produced by the traditional method (TM). In MCM each washing cycle was followed by a centrifugation step for a more effective dewatering and removal of sarcoplasmic proteins (Sp-P). Kamaboko prepared from MCM was whiter and had significantly (p less than 0.05) improved textural characteristics (hardness and gel strength) than that from TM, AAM and PMM. Furthermore, SEM of surimi and kamaboko showed higher number of polygonal structure/mm2 in the gel matrix of MCM kamaboko, as a result of more cross-linking of the myofibrillar proteins, than that recorded for TM, AAM and PMM samples tested. Finally, this study examined the effect of adding common carp sarcoplasmic proteins (Sp-P) on the gel characteristics of threadfin bream surimi and kamaboko. Based on the temperature sweep test, the depths of the valley in the G thermograph of the gels decreased as the concentration of added Sp-P increased from 5% to 35%. Storage modulus (G) of the gels showed greater elasticity in the samples with added Sp-P compared with the control samples without added Sp-P. Furthermore, the breaking force and breaking distance and consequently gel strength of the resultant kamaboko were improved, significantly (p less than 0.05) with added Sp-P. Thus, added Sp-P did not interfere with the gelling of myofibrillar proteins during sol-gel transition phase and was associated with textural quality enhancement for the resultant kamaboko. However, the addition of freeze-dried Sp-P from the dark muscle of the carp decreased the whiteness of the resultant surimi. Furthermore, the gel strength could not be associated with either the number of polygonal structures/mm2 or the area of the polygonal structures.

Thesis (M.S.)--University of Oklahoma, 2005 / Title from title screen (viewed on Dec. 10, 2007). Title from document title page. Includes bibliographical references. Available in PDF format via the World Wide Web.

Il est bien établi que les propriétés mécaniques et rhéologiques d'une large classe de matériaux vitreux amorphes met en jeu - contrairement aux dislocations dans les cristaux - des rearrangements structuraux localisés formant par un processus de cascade des bandes de cisaillements. Cette localisation de la déformation est observée dans divers systèmes vitreux ainsi que dans des simulations numériques. Cette réponse mécanique complexe reste mal comprise à une échelle microscopique et il n'est pas clair si l'écoulement plastique peut être associé à une origine structurale locale ou à des processus purement dynamiques.Dans cette thèse nous envisageons ces problématiques à l'aide de simulations atomiques athermales sur un système Lennard-Jones modèle. Nous calculons le tenseur élastique moyenné localement sur une échelle nanométrique. A cette échelle, le verre est assimilable à un matériau composite comprenant un échafaudage rigide et des zones fragiles. L'étude détaillée de la déformation plastique à différents taux de cisaillement met en évidence divers régimes d'écoulement. En dessous d'un taux de cisaillement critique dépendant de la taille du système, la réponse mécanique atteind une limite quasistatique (effets de taille fini, cascades d'événements plastiques, contrainte seuil) alors que pour des taux de cisaillement plus importants les propriétés rhéologiques sont fixées par le taux de cisaillement imposé. Dans ce régime nous mettons en évidence la croissance d'une longueur de coopérativité dynamique et discutons de sa dépendance avec le taux de cisaillements.

<p>The major issue concerns how the different lignosulfonate types changes the rheological properties of the cement based material (concrete, mortar and cement paste) as a function of temperature and time. In such terms, it is demonstrated that the high molecular weight lignosulfonates performs far better than the low molecular weight ones. The former type also performs considerable better compared to a naphthalene based polymer. </p><p>The above investigation is done with help from the second part of this thesis, which identifies some of the parameters p1, p2,... affecting the shear viscosity η = η ( p1, p2,...) of the cement based material. This is done by investigating the thixotropic behavior of cement paste mixed with either lignosulfonates or naphthalene. The thixotropic behavior is directly related to coagulation, dispersion and re-coagulation of the cement particles. In making the analysis, a modification is applied to the Hattori-Izumi theory, which is a theory about the bookkeeping of the number of reversible coagulated connections between the cement particles. The modification consist, among other things, of include a fading memory to the analysis. That is, the cement paste is allowed to remember its recent past. By a combination of experimental results and numerical simulations, it is demonstrated that such memory term is very important.</p><p>An experimental error is present during a viscometric measurement on concrete (a coaxial cylinders viscometer is used). The error is generated by particle migration. Investigating and compensating for this error constitutes the third part of this thesis. Realizing the nature of this error, some corrections are applied. However, with these corrections, one is only extracting the viscometric values of a "fat'' concrete that surrounds the inner cylinder of the viscometer after the particle migration is basically complete, and not of the concrete in the original homogenous state.</p>

-Glucan is a soluble fibre shown to help regulate blood sugar and lower cholesterol. Incorporation into food, particularly bread, may affect -glucans physicochemical properties and health benefits. The journey of -glucan through the mixing, fermenting, baking, and storage of bread was evaluated, in terms of its solubility and viscosity under in vitro physiological conditions, at levels most likely to be presented to consumers (0.75, 1.0, 1.5 g -glucan/serving). Satiety and glycemic response measures, in addition to the quality and consumer acceptability of the bread, were also investigated. In dough, viscosity of the physiological extract was impacted by -glucan level, fermentation time, and endogenous flour enzymes. Fermentation decreased -glucan solubility indicating that the reduction in viscosity depends on both molecular degradation and solubility reduction. Dough rheological properties and microstructure, characterized using an oscillatory rheometer and fluorescence microscopy, respectively, showed that -glucan may interfere with the gluten network, though gluten addition may help improve this. The breads physical properties supported these observations, as -glucan decreased loaf volume and height, while gluten addition corrected this. Baking increased -glucan solubilization to 58-60%, compared to 9% in dough. Gluten addition increased solubility further (67-68%). Similar trends were seen for extract viscosity and were supported by fluorescence microscopy images. Storage at ambient, refrigeration and frozen conditions showed that bread with -glucan should be consumed fresh to maintain highest bread quality and -glucan solubility and viscosity. Bread with -glucan kept panelists full, longer. Reducing sugar release values implied that satiety may depend on digesta viscosity and/or rate of sugar release from the bread. Bread with -glucan produced the most leveled glucose curve; though areas under the 2 hr plasma glucose curves were similar. Consumers liked the 0.75 g -glucan/serving bread and the control more than the 1.5 g -glucan/serving bread, though provision of health information improved bread liking to similar values. The findings demonstrate that low solubility -glucan concentrate that gets solubilized upon baking is well suited for bakery applications and that a successful -glucan-fortified bread product is possible. Commercialization of bread fortified with -glucan would provide consumers an additional source of dietary fibre to assist them in coming closer to recommended daily intakes. / Food Science and Technology

Polymeric excipients are generally the least well-characterized components of pharmaceutical formulations. The aim of this dissertation work is to facilitate the quality-by-design (QbD) approach to pharmaceutical formulation and manufacturing by evaluating the inter-grade and inter-batch variability of pharmaceutical-grade polymeric excipients. Sodium alginate, a widely used polymeric excipient, was selected for evaluation using appropriate analytical methods and test conditions, especially rheological methods. The materials used were six different grades of sodium alginate and an additional ten batches of one of the grades. &lt;br&gt;To compare the six grades, steady shear measurements were conducted on solutions at 1, 2, and 3% w/w, consistent with their use as thickening or binding agents. Small amplitude oscillation (SAO) measurements were conducted on sodium alginate solutions at higher concentrations (4-13% w/w) corresponding to their use in controlled release matrices. In order to compare the ten batches of one grade, steady shear and SAO measurements were performed on their solutions at 2% w/w and 8% w/w, respectively. Results show that rheological properties of sodium alginate solutions are influenced by both molecular weight and chemical composition of sodium alginate. ¡§One-point¡¨ apparent viscosity data obtained at one low concentration and one shear rate is not representative of the complex rheological behavior of various grades of sodium alginate solutions at higher concentrations or other shear rates. The potential interchangeability of these different grades used as thickening or binding agents could be established by comparing the apparent viscosities of their solutions as a function of both alginate concentration and shear conditions. For sodium alginate used in controlled release formulations, both steady shear (at one low concentration, e.g., 2% w/w) and SAO measurements (at one high concentration indicative of polymer gel state, e.g., 8% w/w) are recommended to be performed on sodium alginate solutions to ensure interchangeability. Furthermore, among batches of the same grade, significant differences in rheological properties were observed, especially at the high solution concentration (i.e., 8% w/w). In summary, inter-grade and inter-batch variability of sodium alginate can be determined using steady shear and SAO methods. &lt;br&gt;The influence of inter-grade and inter-batch variability of sodium alginate on the functionality of sodium alginate used in matrix tablets was investigated with a focus on compression properties, swelling, erosion behavior of alginate matrix tablets, and drug release from matrix tablets. The compression behavior of four grades and three batches of sodium alginate were studied by compaction energetics, out-of-die Gurnham, and out-of-die Heckel analysis. It was found that sodium alginates deform less plastically than microcrystalline cellulose (MCC PH102) but similar to lactose anhydrous. Sodium alginates also demonstrate more elastic deformations during compression than both MCC PH102 and lactose anhydrous. Compacts prepared from multiple batches of the same grade varied in porosity. The same tensile strength of compacts can be achieved by compressing the multiple batches to the same porosity. &lt;br&gt;Sodium alginate tablets undergo both swelling and erosion in water. Grades with substantially higher apparent viscosities at low solution concentration exhibit a higher percentage of water uptake and a low percentage of erosion. Those batches not significantly different in their apparent viscosities at low solution concentration but significantly different in viscoelasticity at high solution concentrations do demonstrate significant differences in their swelling and erosion behavior. Acetaminophen release from sodium alginate matrix tablets prepared from the four grades and three batches can be well described by a zero-order equation. Significant differences in release profile were observed among various grades and batches. &lt;br&gt;In conclusion, the inter-grade and inter-batch variability of sodium alginate has a significant influence on the swelling, erosion, and drug release behavior of sodium alginate matrix tablets. Apparent viscosities of sodium alginate solution at low concentration alone are not sufficient to predict the functionality of sodium alginate used in matrix tablets. Viscoelastic properties of sodium alginate solutions at high concentrations indicative of polymer gel state are appropriate to be characterized. &lt;br&gt;Further study was conducted to determine whether sodium alginate solutions¡&brkbar; rheological parameters are relevant to sodium alginate¡&brkbar;s use in the formulation of calcium alginate gels. Among the grades with similar guluronic acid percentage (%G), there is a significant correlation between gel fracture force and apparent viscosity. However, the results for the partial correlation analysis for all six grades of sodium alginate show that gel fracture force is significantly correlated with %G, but not with the rheological properties of the sodium alginate solutions. Studies of the ten batches of one grade of sodium alginate show that apparent viscosities of their solutions do not correlate with gel fracture force while tan &lt;em&gt;f&lt;/em&gt;Ô values are significantly, but minimally, correlated to gel fracture force. Inter-batch differences in the rheological behavior for one specific grade of sodium alginate are insufficient to predict the corresponding calcium alginate gel's mechanical properties. &lt;br&gt;In summary, rheological methods, including steady shear and small amplitude oscillation, are able to identify the inter-grade and inter-batch variability of sodium alginate. Inter-grade and inter-batch variability of sodium alginate could lead to substantial differences in the functionality of sodium alginate in matrix tablets and in calcium alginate gels. Rheological properties of sodium alginate in solution are suggestive of its functionality as thickeners, or as controlled release agent. However, rheological properties of sodium alginate in solution do not seem to be sufficient to predict the mechanical properties of the corresponding calcium alginate gels. / Mylan School of Pharmacy and the Graduate School of Pharmaceutical Sciences / Pharmaceutics / PhD / Dissertation

Indonesia is one of the countries most prone to natural hazards. Complex interaction of several tectonic plates with high relative velocities leads to approximately two earthquakes with magnitude Mw>7 every year, being more than 15% of the events worldwide. Earthquakes with magnitude above 9 happen far more infrequently, but with catastrophic effects. The most severe consequences thereby arise from tsunamis triggered by these subduction-related earthquakes, as the Sumatra-Andaman event in 2004 showed. In order to enable efficient tsunami early warning, which includes the estimation of wave heights and arrival times, it is necessary to combine different types of real-time sensor data with numerical models of earthquake sources and tsunami propagation. This thesis was created as a result of the GITEWS project (German Indonesian Tsunami Early Warning System). It is based on five research papers and manuscripts. Main project-related task was the development of a database containing realistic earthquake scenarios for the Sunda Arc. This database provides initial conditions for tsunami propagation modeling used by the simulation system at the early warning center. An accurate discretization of the subduction geometry, consisting of 25x150 subfaults was constructed based on seismic data. Green’s functions, representing the deformational response to unit dip- and strike slip at the subfaults, were computed using a layered half-space approach. Different scaling relations for earthquake dimensions and slip distribution were implemented. Another project-related task was the further development of the ‘GPS-shield’ concept. It consists of a constellation of near field GPS-receivers, which are shown to be very valuable for tsunami early warning. The major part of this thesis is related to the geophysical interpretation of GPS data. Coseismic surface displacements caused by the 2004 Sumatra earthquake are inverted for slip at the fault. The effect of different Earth layer models is tested, favoring continental structure. The possibility of splay faulting is considered and shown to be a secondary order effect in respect to tsunamigenity for this event. Tsunami models based on source inversions are compared to satellite radar altimetry observations. Postseismic GPS time series are used to test a wide parameter range of uni- and biviscous rheological models of the asthenosphere. Steady-state Maxwell rheology is shown to be incompatible with near-field GPS data, unless large afterslip, amounting to more than 10% of the coseismic moment is assumed. In contrast, transient Burgers rheology is in agreement with data without the need for large aseismic afterslip. Comparison to postseismic geoid observation by the GRACE satellites reveals that even with afterslip, the model implementing Maxwell rheology results in amplitudes being too small, and thus supports a biviscous asthenosphere. A simple approach based on the assumption of quasi-static deformation propagation is introduced and proposed for inversion of coseismic near-field GPS time series. Application of this approach to observations from the 2004 Sumatra event fails to quantitatively reconstruct the rupture propagation, since a priori conditions are not fulfilled in this case. However, synthetic tests reveal the feasibility of such an approach for fast estimation of rupturing properties. / Indonesien ist eines der am stärksten von Naturkatastrophen bedrohten Länder der Erde. Die komplexe Interaktion mehrer tektonischer Platten, die sich mit hohen Relativgeschwindigkeiten zueinander bewegen, führt im Mittel zu ungefähr zwei Erdbeben mit Magnitude Mw>7 pro Jahr, was mehr als 15% der Ereignisse weltweit entspricht. Beben mit Magnitude über 9 sind weitaus seltener, haben aber katastrophale Folgen. Die schwerwiegendsten Konsequenzen hierbei werden durch Tsunamis verursacht, welche durch diese Subduktionsbeben ausgelöst werden, wie das Sumatra-Andamanen Ereignis von 2004 gezeigt hat. Um eine wirksame Tsunami-Frühwarnung zu ermöglichen, welche die Abschätzung der Wellenhöhen und Ankunftszeiten beinhaltet, ist es erforderlich, verschieden Arten von Echtzeit-Sensordaten mit numerischen Modellen für die Erdbebenquelle und Tsunamiausbreitung zu kombinieren. Diese Doktorarbeit wurde im Rahmen des GITEWS-Projektes (German Indonesian Tsunami Early Warning System) erstellt und umfasst fünf Fachpublikationen und Manuskripte. Projektbezogene Hauptaufgabe war die Erstellung einer Datenbank mit realistischen Bebenszenarien für den Sundabogen. Die Datenbank beinhaltet Anfangsbedingungen für die Tsunami-Ausbreitungsmodellierung und ist Teil des Simulationssystems im Frühwarnzentrum. Eine sorgfältige Diskretisierung der Subduktionsgeometrie, bestehend aus 25x150 subfaults, wurde basierend auf seismischen Daten erstellt. Greensfunktionen, welche die Deformation, hervorgerufen durch Verschiebung an den subfaults ausmachen, wurden mittels eines semianalytischen Verfahrens für den geschichteten Halbraum berechnet. Verschiedene Skalierungsrelationen für Erdbebendimension und slip-Verteilung wurden implementiert. Eine weitere projektbezogene Aufgabe war die Weiterentwicklung des ‚GPS-Schild’-Konzeptes. Dieses besteht aus einer Konstellation von GPS-Empfängern im Nahfeldbereich, welche sich als sehr wertvoll für die Tsunami-Frühwarnung erweisen. Der größere Teil dieser Doktorarbeit beschäftigt sich mit der geophysikalischen Interpretation von GPS-Daten. Coseismische Verschiebungen an der Erdoberfläche, ausgelöst durch das Erdbeben von 2004, werden nach slip an der Verwerfung invertiert. Die Wirkung verschiedener Erdschichtungsmodelle wird getestet und resultiert in der Bevorzugung einer kontinentalen Struktur. Die Möglichkeit von splay-faulting wird untersucht und erweist sich als zweitrangiger Effekt bezüglich der Tsunamiwirkung für dieses Ereignis. Die auf der Quelleninversion basierenden Tsunamimodelle werden mit satellitengestützen Radaraltimetriedaten verglichen. Postseismische GPS-Daten werden verwendet, um einen weiten Parameterbereich uni- und bi-viskoser Modelle der Asthenosphäre zu testen. Dabei stellt sich stationäre Maxwell-Rheologie als inkompatibel mit Nahfeld-GPS-Zeitreihen heraus, es sei denn, eine große Quantität an afterslip, entsprechend etwa 10% des coseismischen Momentes, wird angenommen. Im Gegensatz dazu ist die transiente Burgers-Rheologie ohne große Mengen an afterslip kompatibel zu den Beobachtungen. Der Vergleich mit postseismischen Geoidbeobachtungen durch die GRACE-Satelliten zeigt, dass das Modell basierend auf Maxwell-Rheologie, auch mit afterslip, zu kleine Amplituden liefert, und bekräftigt die Annahme einer biviskosen Rheologie der Asthenosphäre. Ein einfacher Ansatz, der auf einer quasi-statischen Deformationsausbreitung beruht, wird eingeführt und zur Inversion coseismischer Nahfeld-GPS-Zeitreihen vorgeschlagen. Die Anwendung dieses Ansatzes auf Beobachtungen vom Sumatra-Beben von 2004 ermöglicht nicht die quantitative Rekonstruktion der Ausbreitung des Bruches, da die notwendigen Bedingungen in diesem Fall nicht erfüllt sind. Jedoch zeigen Experimente an synthetischen Daten die Gültigkeit eines solchen Ansatzes zur raschen Abschätzung der Bruchausbreitungseigenschaften.