Cette thèse étudie la problématique d'un atterrissage sur un astéroïde. Le lander est un paquet scientifique dépourvu de plateforme de navigation. Il est placé dans une région dont la dynamique est favorable à l'atterrissage. Une étude de l'interaction entre le lander et la surface permet de comprendre quels critères physiques du lander affectent son atterrissage. / This dissertation investigates landings on an asteroid. The lander is a scientific package devoid of any navigation platform. It is released in a region dynamically favorable to landing. The study of the interaction between the lander and the surface shows the possible trade-offs on the lander physical properties that may affect its landing.

The purpose of this paper is to construct a Quasi-volume-filling surface and study its properties. We start with the construction of a volume-filling surface, the Pólya surface, based on Pólya's curve, by rotating the Pólya's curve in 3-dimensional space. Then we construct a Quasi-space-filling curve in 2-dimensions, the Quasi- Pólya curve, which approximates the Pólya's curve and fills a triangle up to a residual small surface of arbitrary size. We prove that the Quasi-Pólya curve satisfies the open set condition, and there exists a unique invariant (self-similar) measure consistent with the normalized Hausdorff measure on it. Moreover, the energy form constructed on Quasi-Pólya curve is proved to be a closed & regular form, and we prove that the Quasi-Pólya curve is a variational fractal in the end. Next, we use the same idea, by rotating the Quasi-Pólya curve in 3-dimensional space, to construct the Quasi-Pólya surface, which is a Quasi-volume-filling surface and approximates to Pólya surface in some sense.

La version actuelle du modèle de surface continentale ISBA représente la couche de sol superficiel et la végétation comme un composite dont les propriétés physiques résultent de pondérations entre les propriétés du sol et de la végétation (albédo, rugosité par exemple). Une nouvelle version, ISBA-MEB (Multi-Energy-Balance), représente le sol et la végétation au travers de deux bilans séparés. Ce développement permet notamment une approche plus réaliste de la modélisation des flux au-dessus, dans et sous de la canopée avec un traitement propre à chacune des couches et la prise en compte de nouveaux processus (effet d'ombrage de la canopée sur le sol, transfert radiatif à travers la végétation, interception de la neige par la canopée). Le sol superficiel est lui désormais caractérisé, pour les surfaces forestières, par une couche de litière agissant sur le cycle énergétique comme sur le cycle hydrologique. Pour évaluer l'impact de ces nouveaux développements sur les forêts, quatre sites Français instrumentés sont dans un premier temps utilisés. Le large panel de données disponible permet une évaluation précise permettant de mettre en évidence certaines améliorations apportées par les développements, En particulier sur le bilan d'énergie en réduisant l'amplitude du flux de chaleur par conduction dans le sol et en réinjectant tout ou partie de cette énergie dans le flux sensible, mais aussi sur le bilan d'eau en améliorant le partitionnement de l'évapotranspiration en ses différentes composantes. Ensuite, leréseau Fluxnet, standard international, se révèle être outil idéal confirmer ces améliorations. Celui ci contient en effet des données relatives à des sites instrumentés correspondant à un large panel de climats et de types de végétation indispensable à la validation d'un modèle destiné à des simulations à échelle globale. 42 sites forestiers sont retenus pour procéder à l'évaluation des nouveaux développements sur la base d'un critère de fermeture du bilan énergétique. Lesrésultats de cette étude permettent non seulement de confirmer à grande échelle les résultats de la partie précédente mais aussi de caractériser des améliorations plus marquées sur les forêts de conifères ainsi que les sites enneigés. Enfin, l'impact sur le bilan hydrologique d'ISBA-MEB est évalué par l'utilisation de la chaîne opérationnelle hydrométéorologique SIM (SAFRAN-ISBAMODCOU).Cette chaîne permet de modéliser le débit des rivières françaises sur une longue période (jusqu'à un demi siècle) et par extension d'obtenir une estimation de la climatologie spatiallement distribuée de l'évapotranspiration. L'impact des développements, et nottament laprise en compte de la litière dans le modèle, modifient l'amplitude annuelle moyenne de l'évaporation du sol et impacte ainsi la modélisation des débits des rvières simulée. D'autre part, une augmentation significative de la sublimation de la neige est à l'origine dans les bassins de montagne d'une réduction du ruisselement total mais ceux-ci ne représente qu'une faible fraction du domaine d'étude. / The current version of ISBA land surface model represents the superficial layer of soil and vegetation as a composite with physical properties modeled as a weighted combination between soil and vegetation properties (e.g. albedo, roughness). A new version, ISBA-MEB (Multi-Energy-Balance), represents the soil and vegetation energy budgets separately. This development consists in a more realistic modeling of the flux exchanges above, within and below the canopy with an explicit treatment of each energy budget and the associated processes (canopy shading of the forest floor, canopy radiative transfer, canopy snow interception and loading, etc.). In addition, the superficial soil layer can be characterized as being comprised of forest litter thereby modulating both thermal and hydrological processes. In order to assess the impact of these developments, first, data from four French well-instrumented sites were used. The wide range of available data permitted a thorough assessment of the impact of the improvements. In particular, the reduced amplitude of the surface ground conduction flux has a profound impact on the energy budget by transferring the resulting residual energy into the sensible heat flux. The water balance was also mainly impacted by improving the partitioning of evapotranspiration into its various components and making it depend more directly on the temporal evolution of the vegetation properties. Next, the Fluxnet network database, which is an international standard for model evaluation, proved to be ideal for confirming these improvements since it is comprised of data from instrumented sites for a wide range of climates and vegetation types. A sub-set of 42 forest sites were selected for assessing the new developments using classical energy balance closure-based criteria. The results of this study not only confirmed the results from the first part of this study for the three French sites, but it also helped characterize the biggest improvements which occurred for moderately open canopies, the pine forest class, and sites with significant snow cover. Finally, the impact of MEB on the hydrological cycle is evaluated by using the SIM operational hydrometeorological chain (SAFRAN-ISBA-MODCOU). This system is used to model and evaluate river discharge over all of France over long periods of time (up to half a century), and by extension, obtain spatially distributed climatological evapotranspiration estimates. The impact of the new developments, especially the combination of the canopy and the explicit forest litter treatment, modified the temporal evolution of bare soil evaporation which had a notable impact on river flow. Finally, significantly increased snow sublimation reduced both total runoff and evapotranspiration in mountain catchments (which comprised a relatively small part of the studied domain).

The purpose of this dissertation was ta determine the usefulness of the linguistic processes of Distortion, Deletion, Generalization, and Semantic Ill-Formedness as constructs which differentiate the verbal communication in families who express dissatisfaction with their current intrafamilial relationships from the verbal communication in families expressing satisfaction with their current relationships. These linguistic constructs provide an intermediate link between abstract theoretical assumptions and concrete findings which abound in the field of family interaction research. Specifically, it was hypothesized that dissatisfied families would use these linguistic structures to a greater extent in their interaction than would satisfied families. Thirty-one family triads, consisting of father; mother, and child were obtained by asking families randomly selected from the local high school student directory to participate. The families were given a Revealed Differences questionnaire and a questionnaire eliciting information regarding their satisfaction with their intrafamilial relationships. The families we~e instructed to reach agreement on items of the Revealed Differences questionnaire which they had disagreed on and the discussion was tape recorded. The discussions were transcribed and each of 150 Surface Structures (a complete thought, usually a grammatical sentence) per family was scored for 11 subcategories of Distortion, Deletion, Generalization, and Semantic Ill-Formedness. Interrater reliabilities ranged from .86 to .98. A mean was computed for the questionnaire pertaining to satisfaction with family relationships. Six families who scored at least one half standard deviation below the mean comprised the "dissatisfied" family group, and six families who scored at least one half standard deviation above the mean comprised the "satisfied" family group. It was found that the dissatisfied families used significantly more Deletion (p The linguistic process of Deletion is theorized to result in impoverishing the speaker's model of the world and the behavioral choices available to the speaker. Similarly, the listener{s) who must respond to the impoverished model is limited in his response and behavioral options. Since all members of the dissatisfied families used this form of language, they perpetuate the impoverishing model of the world and the limitations on their behavior. It was concluded that, while not establishing an etiologic link between the use of Deletion and family dissatisfaction, Deletion is part of the current verbal interaction of families who express dissatisfaction. Further research involving families in which a member is symptomatic is warranted based on the findings of this study. Language may provide at least one form of explanation regarding the process by which families maintain homeostasis in the face of symptom development. The use of linguistic concepts shows promise as an intermediate link in family interaction theory as well as a form of intervention available to therapists.

Polystyrenes with carboxyl end-groups (PS-COOH)and poly (tert-butyl acrylates) (PtBA) of different molar mass were synthesised by anionic polymerisation using n-butyllithium as the initiator. Gel permeation chromatography (GPC) was used to calculate the molecular weight and polydispersity of these polymers. The tacticity of these polymers was determined using Carbon 13 Nuclear Magnetic Resonance Spectroscopy (13C NMR). FT-IR was used to confirm the tacticity of the samples. Matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF) was used to confirm the presence of the carboxyl end-groups. All of the films studied in this project were transferred to mica substrates using the Langmuir-Blodgett deposition method. Both single layer and multiple layer films were constructed using this technique. Atomic force microscopy (AFM) was used to observe the surface topology of these films. / Doctor of Philosophy (PhD) (Science)

The complex interrelations among the different physical processes involved in acid fracturing make it difficult to design, and later, to predict the outcome of stimulation jobs. Actual tendencies require the use of computational models to deal with the dynamic interaction of variables. This thesis presents a new study of acidized surface textures by means of a laser profilometer to improve our understanding of the remaining etched surface topography and its hydraulic response. Visualization plots generated by the profilometer identified hydrodynamic channels that could not be identified by the naked eye in acidized surfaces. The plots clarified the existence of rock heterogeneities and revealed how the processes of dissolution function in chalk rock. Experimental data showed clearly that the effect of dissolution depends on the type of rock and the fluid system; dolomite, for example, dissolves more rapidly but more roughly than limestone. Fluid leakoff rate and temperature also affect the dissolution. Further research is necessary to clarify the effects of conductivity.

Thesis (Ph. D.)--University of Chicago, December 2003. / Includes bibliographical references. Also available on the Internet.

Thesis (Professional Degree)--University of Missouri, School of Mines and Metallurgy, 1922. / The entire thesis text is included in file. Typescript. Title from title screen of thesis/dissertation PDF file (viewed Feb. 22, 2010). Includes bibliographical references (p. 34-35).

No description available.

An apparatus intended to measure the pressure oscillations generated by nanoparticle suspensions in response to an AC electric field was designed and made operational. Electroacoustic measurements were performed on nanoparticle systems covering a range of particle sizes and zeta-potentials, determined using typical particle characterization techniques. The results of the electroacoustic experiments were mapped to the hydrodynamic size and zeta-potentials of the various nanoparticle systems. It was determined that while the electroacoustic technique can be used successfully to measure the motion of nanoparticles in response to an AC electric field, additional improvements to the electroacoustic apparatus are required to allow for a more rigorous mapping of electroacoustic measurements to particle hydrodynamic size and zeta-potential.