Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 225-257). Available also in a digital version from Dissertation Abstracts.

Climate change and warming have been linked to enhanced coastal erosion in the arctic. Specifically, permafrost is believed to be thawing at greater rates, and wave dynamics are expected to increase in intensity. As a result, thermokarst activity, which includes the occurrence of retrogressive thaw slumps, will be more frequent along arctic coasts. / The availability of airborne and spaceborne imagery in the arctic over the last fifty years has made possible the temporal analysis of permafrost and ground ice-related erosion. The objectives of this thesis are (1) the creation of a large scale database for horizontal coastal retreat on Herschel Island for the 1952-2000 timespan, (2) the investigation of retrogressive thaw slump activity over the same period and its relation to coastal erosion, and (3) the elaboration of stereophotogrammetric techniques to investigate retrogressive thaw slump activity volumetrically. Herschel Island, located on the northern coast of the Yukon Territory, was chosen as the study site for this research, because of the widespread presence of retrogressive thaw slumps and the lack of data for coastal erosion during the last fifty years. / Photogrammetric tools were used to create orthorectified and stereo-images of the Island for the years 1952, 1970, 2000 and 2004 from airphoto archives and Ikonos (1 m resolution) imagery. Coastal erosion was found to be stable or declining on Herschel Island except in the vicinity of retrogressive thaw slumps. In addition, retrogressive thaw slumps were identified on the imagery and observed to have increased in frequency for the 1952-2000 period. / Stereophotogrammetric analysis of two retrogressive thaw slumps showed that eroded sediment volumes from these landforms are considerable and should be included in future assessments of sediment release from arctic coasts to the oceanic shelves.

This thesis investigates the geomorphology of retrogressive thaw slumps and active layer slides on Herschel Island, northern Yukon Territory. In particular, it examines the formation and morphology of both landforms, and the ground ice characteristics of retrogressive thaw slumps. During 1988-1989 a number of retrogressive thaw slumps and active layer slides were surveyed and monitored. Field and laboratory investigations involved (1) documentation of landform distribution, setting and morphology, (2) examination of processes of landform formation, and (3) the examination of cryostratigraphy, ground ice characteristics and material properties. / Retrogressive thaw slumps developed in areas of low to moderate slopes underlain by a variety of sediments with ice contents up to 4500% (on a dry weight basis). Slump headwall retreat rates of up to 19.5 m/yr were recorded. By comparison, active layer slides developed on steeper slopes underlain mainly by marine silts and clays. The sediments exposed in the slide floors and headwalls displayed no visible ground ice, but moisture contents were between 15-35%. Retrogressive thaw slumps and active layer slides form by entirely different processes. However, they do occur in close association and are influenced by many of the same parameters.

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This thesis presents the results of investigations in two areasA) Laminar helical flow of Herschel Bulkley fluids in annular space; and B) Cuttings transport in deviated wellbores. Description of area A: This is a theoretical study that consists of the modelling of non-Newtonian fluid flowing through annular space. The rheology of the fluid is represented by a three-parameter fluid model to account for a non-linear behaviour of the rheologic curve followed by the presence of a yield stress. Two distinct methodologies were used to study the effects of inner pipe rotation and inner pipe eccentricity on the velocity profiles of the annular flow. I. Laminar Helical Flow of a Herschel-Bulkley Fluid in a Concentric Annulus and its Extension to a Narrow Eccentric Annulus: The method consists of the use of the boundary conditions to enable the numerical integration of the motion equation. The subsequent extension to eccentric annuli is based on division of the annulus into sectors, where each sector is treated as an equivalent sector of a concentric annulus. Profiles of velocity presented in 2-D and 3-D contour plots explain the effects of eccentricity, inner pipe rotation and yield stress in many different situations. This analysis is useful to simulate the flow field in a borehole during directional drilling and primary cementing particularly for narrow eccentric annuli. II. Laminar Helical Flow of a Herschel-Bulkley Fluid in an Eccentric Annulus and The Special Case of a Pure Axial Flow: A new methodology to obtain the governing equations is proposed here as a first step to the solution of this complicated problem. It consists of eliminating the unknown radial and tangential pressure gradients from the equation of motion by defining vorticity between these two components of the velocity vector. The vorticity equation and the remaining axial component of the motion equation, written in bipolar co-ordinates, are then made discrete using two different finite difference approaches. Firstly, the inertial terms of both equations are made discrete using a modified upwind scheme proposed by O. Axelsson and I. Gustafsson, while the viscous terms are made discrete using central difference approximation. Secondly, the moving boundary conditions are set by enforcing continuity of pressure on the inner annular wall. The future solution of these equations will provide a very accurate model, unavailable until now, that accounts for both effects, the eccentricity and rotation of the drill string, to simulate the flow field of drilling mud in directional and horizontal wells. Description of area B: The fluid models developed are incorporated in the development of two semi-empirical correlations to predict the critical conditions of cuttings transport in deviated weI/bore. The numerical fluid models are modified to predict the velocity of the fluid at the vicinity of the cutting that is at the point of being transported. An extensive bank of data of the critical conditions of transport, emulating many different field conditions, was used in this analysis. The experimental data was provided by an industry sponsored project which did four years of experimental work in a simulated testing column to generate the data. The two semi-empirical correlations developed in this research are based on: • a dimensional analysis of the variables involved in two distinct mechanisms of transport experimentally observed: 1. Rolling or Sliding and 2. Suspension; • a force balance applied to a cutting resting on the low-side wall of an inclined annulus, under fluid dynamic conditions. The semi-empirical correlations can be used as general criteria for evaluating and correlating the effects of various parameters on cuttings transport, and as a guideline for cuttings transport programme design during directional drilling.

Sir William Herschel (1738–1822) was a prominent musician and composer in the 18th century England. He worked as a concert director in several cities. In addition, he was a master of various instruments, and an active solo performer. Herschel composed numerous orchestral and solo works. His music, however, is hardly known today. Many of his compositions remained unpublished, among them the Twenty-Four Caprices for Solo Violin. These caprices are one of the earliest technical studies for the instrument, which must be brought to the intermediate violin students’ and violin teachers’ attentions. The purpose of this study is to create a practical edition of the Twenty-Four Caprices for Solo Violin, and to make it available for violinists by publishing them. The dissertation will look into the performance practice of Hershel’s caprices. Based on a thorough research of the violin methods, the edition will provide fingerings, bowings, and practicing suggestions which are useful for students who wish to improve violin technique. The author of this study strongly believes that these neglected technical studies are extremely beneficial works for violinists, and they deserve to be made public.

In this research an innovative combination of the Herschel-Quincke tubes and traditional liners is proposed for application in noise reduction of aircraft engines. The approach consists of installing Herschel-Quincke (HQ) tubes on lined rectangular ducts. An analytical model was developed to predict the effects of HQ tubes applied to rectangular lined ducts. The technique involves assuming the tube-duct interfaces as finite piston sources. These sources couple the acoustic field inside the duct with the acoustic field within the HQ tubes. The accuracy of the analytical model was validated with experimental data. Three different types of experimental configurations were tested: liner only, HQ tube with a hard wall duct, and HQ tubes with liners. Analytical predictions were shown to correlate well with the experimental data. Two typical types of liners, perforate and linear, were tested in these investigations. The perforate and linear liners with HQ systems showed better sound attenuations than the HQ tubes with hard walled ducts and liners only systems. The performance of the perforate and linear liners with HQ tubes were investigated in various configurations. The results indicated possible combinations which show great potential for reducing the noise within the ducts. / Master of Science

L'écoulement à travers un milieu poreux d'un fluide non newtonien, est un problème récurrent rencontré dans de nombreux domaines de l'industrie et dont la difficulté réside à la fois dans la géométrie complexe du milieu poreux et dans le caractère non-linéaire des matériaux utilisés. Dans cette thèse, nous adoptons une approche différente de celle menée dans les travaux antérieurs, en nous basant principalement sur l'expérimentation. En procédant à des essais systématiques d'injection dans un milieu poreux dont nous pouvons contrôler les données géométriques, nous montrons qu'un gradient de pression seuil, étant proportionnel au seuil du fluide et inversement proportionnel à la taille typique des pores, doit systématiquement être dépassé pour mettre le fluide en écoulement.En outre, nous étudions la possibilité de regrouper, via un redimensionnement, l'ensemble des résultats sur une courbe maîtresse et établir ainsi une base pour l'établissement d'une loi générale d'écoulement / The flow of a non-newtonian fluid through a porous medium is a matter of importance in several industrial applications whose difficulty arises from both the complex geometry of the porous medium and the non-linear behaviour of the complex fluids. In this thesis we investigate the flow of Herschel-Bulkley fluids via a mainly experimental approach and aim to set a generalized law for this particular type of complex fluid in porous medium.Our experimental set-up allows us to perform systematic trials of injection in model porous media whose we can control geometrical parameters. We show that a threshold pressure gradient, proportional to the yield stress and inversely proportional to the particles mean diameter has to be systematically surpassed to make the fluid flow through the porous medium. We also investigate the possibility, thanks to a resizing, to gather all the experimental data on a master curve representative of a generalized law

Le principal objectif de ce travail est d'étudier les propriétés multi-longueurs d'onde d'un échantillon de galaxies pour mieux comprendre leur formation et leur évolution. J'ai utilisé les observations du Herschel en complément de données multi-longueurs d'onde dans le champ. J'ai réalisé une extraction des sources ponctuelles. Des catalogues de sources ont été générés en utilisant la méthode de l'ajustement de PSF. J'ai utilisé des catalogues SPIRE pour rechercher des candidats de galaxies SMG subissant les effets d'une lentille gravitationnelle. J'ai identifié 6 sources dans la liste principale et 55 sources dans une liste supplémentaire. En utilisant des ajustements de SEDs, j'ai ensuite estimé la distribution de redshifts de ces sources, et avons ensuite mené une analyse pour contraindre les propriétés des poussières. J'ai trouvé qu'il est très probable que ces sources soient des systèmes lensés. Mentionnons que parmi nos candidates, j'ai découvert une source rouge unique dont la SED en infrarouge lointain croît et qui semble être une galaxie sub-mm (SMG) fortement lensée à haut redshift. Ce genre de sources est rare et la plupart sont découvertes par hasard. J'ai soumis des propositions photométriques et spectroscopiques pour mesurer le redshift de cette source, en utilisant des observations continues avec IRAM-Nika2, NOEMA et SMA et des observations spectroscopiques avec le télescope de 30m de l'IRAM, NOEMA et GEMINI-nord. Les observations ont permis de mesurer le redshift de la lentille et de la galaxie lensée. Une autre observation sera exécutée avant la fin de l'année. Les résultats sont très prometteurs mais j'ai encore besoin de plus de données. / The main aim of this work is to study the multi-wavelength properties of a sample of galaxies to better understand their formation and evolution. I used the new observations from GALEX and \textit{Herschel} in combination with multi-wavelength data available in the field. I made point source catalogs extracted from the observations of GALEX, and \textit{Herschel} SPIRE and PACS bands using the method of the PSF fitting. Then I used Monte Carlo simulations to quantify the quality of the photometry process and the catalogs.Then I used SPIRE catalogs to search for candidate gravitationally lensed SMGs at high redshift. I identified 6 sources sources in a main list, and 55 sources in a supplementary list. Using SED fitting, performed with CIGALE code, I estimated the redshift distributions of these sources, and constrained their dust properties. I found that, it is very likely that we have gravitationally lensing systems. It should be mentioned that within our candidates we have discovered a unique red source with a rising Far-IR SED, which appears to be a strongly lensed submillimeter galaxies at z~5.2. This kind of sources are quite rare on the sky and are serendipitously discovered. I proposed some followup photometric and spectroscopy observation to measure the redshift of this sources, using for instance continuum observations with IRAM-Nika2, NOEMA, and SMA, and spectroscopic observation with IRAM 30m telescope, NOEMA, and GEMINI-North. The GEMINI-North observations succeeded in measuring the redshifts of the lens and of the lensed galaxy. One more will be executed at the end of this year. The results is quite promising, but more data are needed.