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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
171

Field Ecology Patterns of High Latitude Coral Communities

Foster, Kristi A. 01 November 2011 (has links)
Some climate models predict that, within the next 30-50 years, sea surface temperatures (SSTs) will frequently exceed the current thermal tolerance of corals (Fitt et al. 2001; Hughes et al. 2003; Hoegh-Guldberg et al. 2007). A potential consequence is that mass coral bleaching may take place (i) during warm El Niño-Southern Oscillation (ENSO) events which are predicted to occur in some regions more frequently than the current 3-7 year periodicity (Hoegh-Guldberg 1999; Sheppard 2003) or (ii) perhaps as often as annually or biannually if corals and their symbionts are unable to acclimate to the higher SSTs (Donner et al. 2005, 2007). Global data also indicate an upward trend toward increasing frequencies, intensities, and durations of tropical hurricanes and cyclones (Emanual 2005; Webster et al. 2005). As coral communities have been shown to require at least 10-30 years to recover after a major disturbance (e.g. Connell 1997; Ninio et al. 2000; Bruno & Selig 2007; Burt et al. 2008), it is possible that future coral communities may be in a constant state of recovery, with regeneration times exceeding the periods between disturbances. Life history traits (e.g. reproduction, recruitment, growth and mortality) vary among species of hard corals; thus, gradients in community structures may have a strong influence on susceptibilities to disturbance and rates of recovery (Connell 1997; Ninio & Meekan 2002). Taxa which are more susceptible to bleaching and mechanical disturbance (e.g. tabular and branching acroporids and pocilloporids) may experience continual changes in population structure due to persistent cycles of regeneration or local extirpation, while the more resistant taxa (e.g. massive poritids and faviids) may display relatively stable population structures (Woodley et al. 1981; Hughes & Connell 1999; Baird & Hughes 2000; Marshall & Baird 2000; Loya et al. 2001; McClanahan & Maina 2003). Determining whether resistant coral taxa have predictable responses to disturbances, with consistent patterns over wide spatial scales, may improve predictions for the future affects of climate change and the composition of reefs (Done 1999; Hoegh-Guldberg 1999; McClanahan et al. 2004). The work presented in this dissertation describes the spatial and temporal patterns in community structures for high latitude coral assemblages that have experienced the types of natural disturbances which are predicted to occur in tropical reef systems with increasing frequency as a result of climate change. The primary area of focus is the southeastern Arabian Gulf, where the coral communities are exposed to natural conditions that exceed threshold limits of corals elsewhere in the world, with annual temperature ranges between 14-36°C (Kinzie 1973; Shinn 1976) and salinities above 40 ppt. Two additional regions are included in this study for comparisons of high latitude coral community structures. The northwestern Gulf of Oman is adjacent to the southeastern Arabian Gulf (i.e. the two bodies of water are connected by the Strait of Hormuz); however, the environmental conditions are milder in the Gulf of Oman such that the number of coral taxa therein is threefold that found in the southeastern Arabian Gulf (i.e. 107 coral species in the Gulf of Oman compared to 34 species in this region of the Arabian Gulf (Riegl 1999; Coles 2003; Rezai et al. 2004)). Broward County, Florida is geographically remote from the Gulfs and, therefore, serves as a benchmark for testing whether consistent patterns in community structures exist despite different climatic and anthropogenic influences. The coral communities within the southeastern Arabian Gulf, the northwestern Gulf of Oman, and Broward County, Florida have been exposed to recurrent elevated sea surface temperature (SST) anomalies, sequential cyclone and red tide disturbances, and frequent hurricanes and tropical storms, respectively. These disturbances and other impacts (e.g. bleaching episodes, disease outbreaks, anthropogenic stresses) have affected the more susceptible acroporids and pocilloporids, resulting in significant losses of coral cover by these families and shifts towards massive corals as the dominant taxa. During the post-disturbance scarcity or absence of branching and tabular corals, the resistant massive taxa have become the crux of the essential hard coral habitat for fish, invertebrates and other marine organisms. Because recovery to pre-disturbance community structures may take decades or may not occur at all, it is vital that scientists and resource managers have a better understanding of the spatial and temporal ecology patterns of the corals that survive and fill in the functional gaps that are created by such disturbances. To aid in this understanding, this dissertation presents spatial and temporal patterns for the coral assemblages which have developed after the respective disturbances. Spatial ecology patterns are analyzed using graphical descriptions (e.g. taxa inventories, area cover, densities, size frequency distributions), univariate techniques (e.g. diversity indices), distributional techniques (e.g. k-dominance curves) and multivariate techniques (e.g. hierarchical clustering, multidimensional scaling). Temporal comparisons at monitoring sites within the southeastern Arabian Gulf and northwestern Gulf of Oman describe the coral population dynamics and are used to create size class transition models that project future population structures of massive corals in the recovering habitats.
172

Estimation des niveaux marins extrêmes avec et sans l’action des vagues le long du littoral métropolitain / Estimation of extreme marine sea levels with and without wave component along the French coasts

Kergadallan, Xavier 01 October 2015 (has links)
Pour caractériser le risque de submersion marine, il est très important d'avoir une connaissance précise des lois de distribution des niveaux d'eau marins, et plus particulièrement des niveaux d'eau extrêmes. En effet ce sont eux qui sont à l'origine des conséquences les plus dramatiques. Le programme de recherche mené au cours de cette thèse a été financé par le Ministère de l'Écologie, du Développement Durable et de l'Énergie. L'objectif final est de fournir des valeurs de référence de niveau d'eau marin le long des côtes françaises, par le biais d'une méthode d'analyse statistique des extrêmes. Ces niveaux comprennent les trois composantes suivantes : la marée, la surcote météorologique et le wave set-up. Le principe de base utilisé est le suivant : une analyse statistique est effectuée aux ports où la donnée marégraphique est disponible, puis le résultat est interpolé entre les ports. Différentes approches sont testées. Les points suivants sont en particulier étudiés :- la dépendance marée surcote, avec deux différents types de dépendance, une dépendance temporelle et une dépendance en amplitude ;- la méthode d'interpolation, avec la comparaison d'une analyse site-par-site (ASS) avec une analyse régionale (RFA), et celle d'interpolations 1D et 2D ;- l'estimation du wave set-up, basée sur l'état de l'art des formules paramétriques ;- la dépendance surcote vagues, avec des lois bi-variées de valeurs extrêmes. Le résultat final se présente sous la forme de deux profils de niveau d'eau de période de retour 100 ans : le premier sans l'action des vagues (marée et surcote météorologique) et le deuxième avec l'action des vagues. Les valeurs les plus élevées sont atteintes, pour le littoral de la Mer du Nord, la Manche et l'Atlantique, en Baie du Mont-Saint-Michel (à cause des conditions de marée), et pour le littoral méditerranéen au niveau de Marseille. L'analyse montre que la modélisation de la dépendance temporelle marée surcote n'influe pas significativement sur les estimations des valeurs extrêmes. Par contre la modélisation de la dépendance en amplitude donne des résultats intéressants pour certains ports. En comparaison avec l'ASS, la RFA tend à lisser les résultats. Les estimations issues de la RFA sont supérieures pour le littoral méditerranéen, et équivalentes pour le littoral de Mer du Nord, Manche et Atlantique. La RFA serait recommandée pour l'estimation des niveaux de retour en dehors du domaine de validité de l'ASS.À cause du petit nombre de sites d'observation, il est préféré une interpolation 1D le long du trait de côte lissé. Le wave set-up est calculé par la formule de Dean et Walton [2009].La dépendance surcote vagues est moyenne le long du littoral méditerranéen. Le facteur de dépendance montre des variations plus importantes le long du littoral de Mer du Nord, Manche et Atlantique, avec un maximum observé en Baie de Seine et des minima en Baie de Mont-Saint-Michel et au niveau de Calais. Des suggestions sont faites pour améliorer les méthodologies développées et appliquées dans le cadre d'un futur travail / Accurate knowledge of the statistical distribution of extreme sea levels is of the utmost importance for the characterization of flood risks in coastal areas, with a particular interest devoted to extreme water levels because they may induce the most dramatic consequences. Research was funded by the French Ministry of Ecology, Sustainable Development and Energy to identify the risk of flooding from the sea in France. The aim is to provide values on design levels along the French coasts by a statistical method of extreme value analysis. These levels must include the effect of the three following components: tide, meteorological surge and wave set-up. The principle is as follows: an analysis is carried out at the harbours, where seal level observations are available, then the result is interpolated between the harbours. Different approaches are tested. In particularly, the following specific items are studied:- the tide surge dependence, with two different types of dependence: a temporal dependence and an amplitude dependence;- the interpolation method: with the comparison of a site-by-site analysis (SSA) with a Regional Frequency Analysis (RFA), and a 1-D with a 2-D interpolation;- the estimation of the wave set-up, based on the state of art of parametric formula;- the surge wave dependence, with the bivariate laws of extreme values. The final result is two profiles of the 100-year water level: one for the still water level (tide and meteorological surge), and the other for the sea level with the wave set-up. The highest sea levels are located, for the English Channel and Atlantic coasts at the Saint-Michel-bay (because of the tide), and for the Mediterranean coast around Marseille. The analysis shows that the temporal tide surge dependence has no effect on the estimation of the sea level extreme values. In contrast, the model of the amplitude tide surge dependence shows some interesting results for few harbours. In comparison with the SSA, the RFA tends to smooth the result. RFA estimates are higher along the Mediterranean coast, and similarly along the English Channel and Atlantic coasts. RFA would be recommended for estimating return levels out of the SSA validity domain. Because of the small number of observation sites, a 1-D interpolation, along a smoothed coastline, is preferred. The wave set-up is calculated with the formula of Dean and Walton [2009].The surge wave dependence is medium along the Mediterranean coast. Variations of the dependence factor are more important along the English Channel and the Atlantic coasts, with a maximum at the bay of the Seine and some minima at the bay of Saint-Michel and Calais. Some ideas are provided to perform the methodology for further work
173

Dynamique et échanges sédimentaires en rade de Brest impactés par l'invasion de crépidules / Dynamic and exchanges of sediments in the bay of Brest impacted by the invasion of slipper limpets

Beudin, Alexis 12 December 2014 (has links)
Cette thèse est une contribution à l’étude de la dynamique sédimentaire dans l’écosystème de la rade de Brest. Elle a pour objectif de décrire, par la simulation numérique et l’observation in situ, le mouvement des masses d’eau et de sédiments sous l’influence de la marée à l’échelle de la rade, et l’impact de la distribution spatiale actuelle des populations de crépidules sur le transport de sédiments en suspension et l’évolution des fonds. Un modèle bidimensionnel horizontal (2DH) est mis en œuvre à partir du code TELEMAC. Il intègre la variabilité spatiale du substrat, et rend compte de la présence physique (macro-rugosité, partition de la contrainte de cisaillement) et de l’activité biologique (filtration de l’eau chargée de particules en suspension, production de biodépôts) des crépidules. Les mesures de hauteur d’eau, de vitesse du courant, et de vitesse de frottement valident de façon satisfaisante les choix de paramétrisation du modèle hydrodynamique. Les mesures de concentration de matière en suspension en rade de Brest sont sporadiques, et leur analyse est compliquée. Le modèle sédimentaire constitue un outil de compréhension. Il informe de l’évolution temporelle de la contribution de différents types de sédiments et de leur origine aux concentrations locales de sédiments en suspension et déposés. Il permet de suivre le cheminement des sédiments principalement en suspension, de quantifier les échanges entre les sous-bassins de la rade et avec le fond. L’introduction sur le fond des colonies de crépidules, sous forme de chaînes assimilées à des cylindres, induit une diminution de la vitesse du courant à l’aplomb et dans leur sillage, compensée par une augmentation en périphérie, entraînant une modification globale des zones d’érosion et de dépôt de sédiments. Localement, les macro-rugosités ont un effet antagoniste selon leur répartition: des densités moyennes augmentent le frottement de peau et les remises en suspension, tandis que des densités élevées induisent un masquage des sédiments sur le fond duquel résulte une accrétion. Par comparaison à leur impact hydrodynamique, l’activité biologique des crépidules joue un rôle secondaire sur la dynamique sédimentaire. / This thesis is a contribution to the study of sediment dynamic in the ecosystem of the bay of Brest. It aims at describing, by numerical simulations and field observations, the movement of water and sediments in the bay under tidal forcing, and the impact of the present spatial distribution of slipper limpets on suspended sediment transport and bed evolution. A two-dimensional horizontal (2DH) model is implemented based on the TELEMAC numerical system. It integrates the spatial variability of bed sediments, accounts for the physical presence (macro-roughness, form drag - skin friction partitioning) and biological activity (filtration of water carrying suspended particles, production of biodeposit) of slipper limpets. Measurements of water level, mean flow velocity, and friction velocity satisfactorily validate the choice of parameters in the hydrodynamic model. Measurements of suspended matter concentration in the bay of Brest are sporadic, and their analysis complicated. The sediment model stands as a tool for better understanding sedimentary processes. It informs the temporal evolution of the contribution of different types of sediment, and their origin, to local suspended and deposited sediment concentrations. It allows to follow the paths of sediment transport predominantly in suspension, and to quantify the exchanges of sediments between the sub-basins of the bay and with the bed. The introduction of slipper limpet colonies on the bed, in the form of chains assimilated as cylinders, induces decreasing flow velocity above and in their wake, compensated by increasing flow velocity on the outskirts, which globally modify the patterns of sediment erosion and deposition in the bay. Locally, the macro-roughness elements have an antagonist effect depending on their distribution: medium densities increase skin friction and erosion flux, whereas high densities shelter bed sediments from which results accretion. By comparison to their hydrodynamic impact, the biological activity plays a secondary role on sediment dynamic.
174

O processo de demarcação dos terrenos de marinha : uma releitura em conformidade com a constituição de 1988

Dantas, Fernando Luis Lopes 23 February 2015 (has links)
Tide lands are owned by the Union, pursuant to art. 20, VII, of the Constitution of 1988. Despite this reference, the Constitution did not try to present the characteristic features of these assets, nor specifically ruled on its demarcation process, and these issues governed by constitutional legislation, in particular by Decree law No. 9760, issued in 1946. Since then, Brazil has owned four other beyond 1988. With this Constitution, rather than bring together the state of democratic experience, there was the so-called phenomenon of constitutionalization of Administrative Law. A new behavioral paradigm was established for Public Administration, which has been governed closely by constitutional rules, which elected the process as the primary form of performance of government agencies. The constituent power also took care to define the elements considered essential to the development of a fair trial, that beyond simple compliance to certain procedural specific regulations, is based on the firm commitment to carry out the fundamental rights of individuals. Given the new state model designed by the 1988 Constitution, imposed the need to promote a review of the various specific regulations on State processes in order to conform them to existing constitutional requirements. And this opportunity, especially the temporal distance from when edited Decree-Law No. 9,760 / 1946, as well as the anti-democratic context in the midst of which was issued, the review of the normative discipline of demarcation activity of tide lands appeared as urgent measure. Rereading promoted this work was guided by axiological vector announced from the constitutional preamble: the realization of justice and fundamental rights of individuals, in particular where the right to property and the procedural. Although that lacks Decree Law update, this measure does not seem essential, since their harmonization with the constitutional provisions and the provisions of Law No. 9,784 / 1999, which can be performed only from hermeneutical resources, which must honor the supremacy and the normative force of the Constitution. It follows, first of all, the requirement that the demarcation activity is promoted without remission or emptying of the procedural formula. Your result should pinpoint the location of tide lands with strict attention to the essential elements that make up the legal concept of this institute: the spatial framework, which is the line is the average of high tides, the temporal reference to the year 1831 and finally the systematic calculation of those averages. Should not interest the Union, as one of the entities that embodies the state, as its state even one square centimeter beyond what the Constitution gave it, as this would represent a breach of the duty of protection to which it is bound, and that overlaps any secondary interest, notably revenue collection. The due process of demarcation, which meets all requirements of legal and constitutional framework, is therefore the only instrument able to promote necessary and possible harmonization between the interests of the Union and individuals in general. / Os terrenos de marinha são de propriedade da União, conforme dispõe o art. 20, VII, da Constituição de 1988. A despeito dessa referência, o texto constitucional não tratou de apresentar os elementos característicos desses bens, nem dispôs especificamente sobre o seu processo de demarcação, estando essas questões disciplinadas pela legislação infraconstitucional, em especial pelo Decreto-lei n.º 9.760, expedido em 1946. Desde então, o Brasil já possuiu outras quatro, além da Constituição de 1988. Com esta, mais do que a reaproximação do Estado da experiência democrática, verificou-se o fenômeno que se convencionou chamar de constitucionalização do Direito Administrativo. Um novo paradigma de comportamento foi estabelecido para a Administração Pública, que passou a ser regulada bem de perto pelas normas constitucionais, as quais elegeram o processo como forma primordial de atuação dos órgãos do Estado. O Poder Constituinte também cuidou de definir os elementos que considerou essenciais para o desenvolvimento de um processo justo, que além da simples observância a determinados regramentos procedimentais, fundamenta-se no firme compromisso de realizar os direitos fundamentais dos indivíduos. Diante do novo modelo de Estado desenhado pela Constituição de 1988, impôs-se a necessidade de se promover uma revisão dos diversos regramentos dos processos estatais, de modo a conformá-los às normas constitucionais vigentes. E a este ensejo, sobretudo pela distância temporal desde quando editado o Decreto-lei n.º 9.760/1946, bem como pelo contexto antidemocrático em meio ao qual foi expedido, o reexame da disciplina normativa da atividade demarcatória dos terrenos de marinha se apresentava como medida inadiável. A releitura promovida neste trabalho foi orientada pelo vetor axiológico anunciado desde o preâmbulo constitucional: a realização da justiça e dos direitos fundamentais dos indivíduos, no caso especial o direito de propriedade e os processuais. Embora o referido Decreto-lei careça de atualização, tal providência não se mostra imprescindível, pois sua harmonização com as normas constitucionais e com as disposições da Lei n.º 9.784/1999, é passível de ser realizada apenas a partir de recursos hermenêuticos, os quais devem prestigiar a supremacia e a força normativa da Constituição. Disso decorre, antes de tudo, a obrigação de que a atividade de demarcação seja promovida sem a dispensa ou o esvaziamento da fórmula processual. O seu resultado deve apontar a localização dos terrenos de marinha com estrita atenção aos elementos essenciais que integram o conceito legal desse instituto: o marco espacial, que é a linha correspondente à média das preamares, a referência temporal ao ano de 1831, e, por fim, a sistemática de cálculo daquela média. Não deve interessar à União, como um dos entes que personifica o Estado, afirmar como seu sequer um centímetro quadrado além daquilo que a Constituição lhe conferiu, pois isso representaria o descumprimento do dever de proteção ao qual ela se encontra vinculada, e que se sobrepõe a qualquer interesse secundário, notadamente o arrecadatório. O justo processo de demarcação, que observe todos os requisitos estabelecidos no ordenamento jurídico-constitucional, é, portanto, o único instrumento apto a promover a necessária e possível harmonização entre os interesses da União e dos indivíduos em geral.
175

At low tide : an absence of water, and abundance of plastic

Obermeyer, Chloe 02 1900 (has links)
This project deals with the concepts of care, contentedness and self-reflection in light of the ecological plights that face our planet and the way that my artistic practice reflects this. It achieves this by focusing on marine forms of plastic pollution along Cape Town’s coastline as well as on the water resources during Cape Town’s water crisis that started in 2017. To unite these areas of interest, the conceptual platform and the visual associations of “a low tide” were used to navigate material and practical considerations of my chosen alternative photographic media and how they can best address such interests. / Art and Music / M.V.A.
176

Subsurface Depositional Systems Analysis of the Cambrian Eau Claire Formation in Western Ohio

Laneville, Michael Warren 26 November 2018 (has links)
No description available.
177

Konstrukční řešení reverzní vírové turbiny / Construction of reversible swirl turbine

Kosar, Jakub January 2020 (has links)
The thesis deals with the construction design of reversible swirl turbine used in a tidal range power plant for bidirectional operation. The theoretical part provides an overview of state-of-the-art technologies in the usage of tidal energy, mostly by means of tidal range and stream tidal power plants. It also analyses respective designs of tidal turbines and their advantages and disadvantages. The practical part of the thesis demonstrates individual steps applied when examining loading forces and also shows the design method and strength inspection procedure of the turbine and its parts, especially of the impeller, gears, shafts and bearings. Lastly, the paper outlines the selection approach of the most appropriate water plant generator.
178

L'extension artificielle des côtes vers le large et ses conséquences en droit international/Coastal artificial extension and its consequences in international law

Thang, Nguyen Toan 05 December 2005 (has links)
La thèse aborde une question originale et d'actualité: l'extension artificielle des côtes. Afin de mieux comprendre ce phénomène dans son actualité, la thèse attache une importance à la description de la pratique des États en fournissant les informations aussi précises, aussi actuelles et aussi concrètes que possible. C'est à partir de cette pratique que la thèse répond à la question de savoir comment les règles de droit répondent aux exigences de la pratique. En ce qui concerne la pratique des États, la thèse explique, dans une première partie, que l'extension artificielle des côtes est destinée, tantôt, à protéger les côtes contre l'élévation du niveau de la mer, tantôt à gagner des terres pour diverses fins: habitat humain, agricoles, développement des ports et de leurs infrastructures pour les besoins des navires modernes et du commerce international. Mais parallèlement, cette extension entraîne des effets négatifs pour l'écosystème côtier (chapitre I). Des travaux de ce genre ont été menés, ou vont l'être, en Europe (Pays-Bas, Allemagne, Belgique, France, R.-U., etc), aux États-Unis, en Asie (Bahreïn, Malaisie, Hong Kong, Singapour, Japon), en Australie, et sur certains archipels du Pacifique (chapitre II). La seconde partie de la thèse examine le droit applicable au phénomène d'extension artificielle des côtes. Sont ainsi passées en revue: les règles relatives à la navigation (chapitre III), les règles relatives aux lignes de base (chapitre IV), les règles relatives aux hauts-fonds découvrants (chapitre V), les règles relatives aux îles et aux rochers (chapitre VI) et enfin les règles relatives à la protection de l'environnement marin (chapitre VII).
179

Ecoulements oscillatoires et effets capillaires en milieux poreux partiellement saturés et non saturés : applications en hydrodynamique côtière / Oscillatory flows and capillary effects in partially saturated and unsaturated porous media : applications to beach hydrodynamics

Alastal, Khalil 16 May 2012 (has links)
Dans cette thèse, on étudie les écoulements oscillatoires en milieux poreux (non saturés ou partiellement saturés) dus à des oscillations tidales des niveaux d'eau dans des milieux ouverts adjacents aux milieux poreux. L'étude est centrée sur le cas des plages de sable en hydrodynamique côtière, mais les applications concernent, potentiellement et plus généralement, les problèmes d'oscillation et de variation temporelle des niveaux d'eau dans des systèmes couplés, lorsque ceux-ci mettent en jeu des interactions entre les écoulements de sub-surface (milieux poreux) et les eaux de surface (milieux ouverts) : plages naturelles et artificielles; digues portuaires; barrages en terre; berges de fleuves; estuaires. Le forçage tidal des écoulements souterrains est représenté et modélisé ici, tant expérimentalement que numériquement, par une oscillation quasi-statique du niveau d'eau dans un réservoir externe ouvert, connecté au domaine poreux. On s'intéresse plus particulièrement aux écoulements verticaux forcés par une pression oscillatoire imposée au bas d'une colonne de sol. Sur le plan expérimental, ce type de forçage est obtenu par une machine à marée équipée d'un arbre rotatif. Au total, on utilise dans ce travail trois types d'approches (expérimentale, numérique, analytique), l'objectif étant d'étudier le mouvement vertical de la surface "libre" et l'écoulement non saturé sus-jacent, de façon à prendre en compte aussi bien les pertes de charge dans la zone saturée que les gradients de pression capillaire dans la zone non saturée. […] / In this thesis, we study hydrodynamic oscillations in porous bodies (unsaturated or partially saturated), due to tidal oscillations of water levels in adjacent open water bodies. The focus is on beach hydrodynamics, but potential applications concern, more generally, time varying and oscillating water levels in coupled systems involving subsurface / open water interactions (natural and artificial beaches, harbor dykes, earth dams, river banks, estuaries). The tidal forcing of groundwater is represented and modeled (both experimentally and numerically) by quasi-static oscillations of water levels in an open water reservoir connected to the porous medium. Specifically, we focus on vertical water movements forced by an oscillating pressure imposed at the bottom of a soil column. Experimentally, a rotating tide machine is used to achieve this forcing. Overall, we use three types of methods (experimental, numerical, analytical) to study the vertical motion of the groundwater table and the unsaturated flow above it, taking into account the vertical head drop in the saturated zone as well as capillary pressure gradients in the unsaturated zone. Laboratory experiments are conducted on vertical sand columns, with a tide machine to force water table oscillations, and with porous cup tensiometers to measure both positive pressures and suctions along the column (among other measurement methods). Numerical simulations of oscillatory water flow are implemented with the BIGFLOW 3D code (implicit finite volumes, with conjugate gradients for the matrix solver and modified Picard iterations for the nonlinear problem). In addition, an automatic calibration based on a genetic optimization algorithm is implemented for a given tidal frequency, to obtain the hydrodynamic parameters of the experimental soil. Calibrated simulations are then compared to experimental results for other non calibrated frequencies. Finally, a family of quasi-analytical multi-front solutions is developed for the tidal oscillation problem, as an extension of the Green-Ampt piston flow approximation, leading to nonlinear, non-autonomous systems of Ordinary Differential Equations with initial conditions (dynamical systems). The multi-front solutions are tested by comparing them with a refined finite volume solution of the Richards equation. Multi-front solutions are at least 100 times faster, and the match is quite good even for a loamy soil with strong capillary effects (the number of fronts required is small, no more than N≈ to 20 at most). A large set of multi-front simulations is then produced in order to analyze water table and flux fluctuations for a broad range of forcing frequencies. The results, analyzed in terms of means and amplitudes of hydrodynamic variables, indicate the existence, for each soil, of a characteristic frequency separating low frequency / high frequency flow regimes in the porous system.
180

Beyond sexual satisfaction : pleasure and autonomy in women’s inter-war novels in England and Ireland

Bacon, Catherine M. 15 June 2011 (has links)
My dissertation offers a new look at how women authors used popular genres to negotiate their economic, artistic, and sexual autonomy, as well as their national and imperial identities, in the context of the changes brought by modernity. As medical science and popular media attempted to delineate women’s sexual natures, Sylvia Townsend Warner, Winifred Holtby, Kate O’Brien, and Molly Keane created narratives which challenged not only psychoanalytic proscriptions about the need for sexual satisfaction, but traditional ideas about women’s inherent modesty. They absorbed, revised, and occasionally rejected outright the discourses of sexology in order to advocate a more diffuse sensuality; for these writers, adventure, travel, independence, creativity, and love between women provided satisfactions as rich as those ascribed to normative heterosexuality. I identify a history of queer sexuality in both Irish and English contexts, one which does not conform to emergent lesbian identity while still exceeding the limits of heteronormativity. / text

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