No description available.

Cette thèse se donne pour enjeu de redéfinir l'identité littéraire de Mark Twain dans son articulation avec l'histoire. Clef de voûte de la mythologie nationale qui donne forme à l'identité américaine, le motif de la trace devient chez Twain un principe d'écriture où s'exprime une conscience historique dissidente. La réappropriation progressive de ce paradigme subvertit les représentations collectives pour définir une compréhension singulière de l'historicité de la nation et du devenir individuel. L'opposition entre la trace mnésique, inscription de l'histoire dans la profondeur du lieu, et la trace prospective, ébauche d'un tracé nouveau, structure dès l'origine les représentations symboliques de l'Ancien et du Nouveau Continent. À ces deux modalités de l'inscription correspondent chez Twain deux formes d'historicité, la stase et le progrès, et deux régimes politiques, la monarchie et la démocratie. Or son écriture subvertit cette polarité symbolique en dénonçant la stratification de l'histoire américaine, symptôme d'une dérive monarchique due à la perte des origines fondatrices de la nation. Se définit dès lors une économie historique où la trace des origines de la nation se révèle habitée par un régime de perte qui contamine quiconque cherche à les capter, tandis que le déterminisme des origines individuelles impose l'idée d'une fermeture de l'histoire. À l'emprise mortifère de la trace, l'écriture de Twain oppose l'utopie de la non-inscription, principe d'une sortie de l'histoire et d'une coïncidence retrouvée avec l'origine. La résurgence de tensions irrésolues dans les textes tardifs convertit cependant cette utopie en mise en scène de l'abolition de l'histoire. / : This thesis aims at redefining Mark Twain's literary identity in its articulation with history. The motif of the trace, which stands at the core of the national mythology that shapes American identity, is in Twain a writing principle expressing a dissident historical consciousness. The progressive reappropriation of this paradigm subverts collective representations and defines a singular apprehension of national and individual historicity. The opposition between the mnesic trace—which inscribes history into a place—and the prospective one—the starting point of a new tracing—lies at the root of the symbolical representations of the Old and the New Continents. In Twain's writings, these two forms of inscription correspond to two opposite modes of historicity—stasis and progress—and two political regimes—monarchy and democracy. Twain nevertheless subverts this symbolical polarity by revealing the stratification of American history. He thereby hints at a drift towards monarchy that results from the loss of the nation's founding principles. His fiction thus defines a historical economy in which the traces of the nation's origins appear to be inhabited by a principle of loss that may contaminate whoever attempts to appropriate them. The determinism of individual origins meanwhile suggests the closing down of history. To the deadly hold of the trace, his writings oppose the utopia of non- inscription – the principle of an escape from history and of a renewed coincidence with the origins. Yet the resurgence of unsolved tensions in Twain's late works converts the utopia into the staging of the abolition of history.

Ce travail présente une analyse de l'évolution morphologique et des processus sédimentaires actuels du plateau continental interne sud-aquitain, (sud-est du Golfe de Gascogne, France),secteur riche en données, mais sur lequel de nombreuses questions restent néanmoins en suspens. Il s'articule autour de deux zones ateliers complémentaires : la zone de « La Salie-Biscarrosse » sur le plateau continental interne sud-aquitain au sud des passes du Bassin d'Arcachon (entre 5 et 50 m de profondeur d’eau), et la tête du canyon de Capbreton et ses abords (entre 5 et 120 m de profondeur d’eau). Deux approches sont utilisées : (1) une approche descriptive et comparative (dans le temps), utilisant des données géo-acoustiques(sondeur multi faisceaux, sonar latéral et sondeur de sédiments), des prélèvements et (2) une approche mettant en oeuvre des modélisations numériques des interactions houles / courants /sédiments. Les résultats obtenus sur le plateau interne aquitain ont permis d'améliorer la connaissance de la morphologie, de la nature et de la géométrie interne des corps sédimentaires, d'étudier leur évolution au cours des 29 dernières années (entre 1984 et 2013)et de proposer des facteurs à l’origine de cette évolution. Le résultat majeur est la mise en évidence de « sorted bebforms » entretenus par la houle; dont la surprenante migration vers le nord-est est à associer à la récente découverte d'intenses épisodes de « poleward current » sur le plateau. Le suivi entre 1998 et 2013 de l’évolution morphologique de la tête du Canyon de Capbreton, située à seulement 250 m du littoral montre une évolution rapide qui fluctue cependant autour d'une position d'équilibre. Par ailleurs l’influence de la dérive littorale sur les transferts de sédiments du plateau vers le canyon a pu être démontrée. En-effet, les arguments morphologiques et sédimentaires, associés à la modélisation numérique, prouvent que la dérive littorale aquitaine alimente épisodiquement (conditions de houle forte) la tête de canyon en sables littoraux. / This study proposes an analysis of the morphological evolution and recent sedimentary processes of the south Aquitaine inner shelf (south east Bay of Biscay, France). This area is greatly documented but improvement of our knowledge is needed for a better understanding.Two complementary study areas are analyzed: « La Salie-Biscarrosse » area of the south-Aquitaine inner shelf (in a water depth extending from 5 to 50 m), and the head of the Capbreton Canyon (in a water depth extending from 5 to 120 m). Two approaches are used:(1) a descriptive and comparative analysis of the geophysical and sedimentological data setsand (2) a numerical modeling taking into account swell, current and sediments. The results obtained allow the description and the interpretation of the morphology, the nature, the internal geometry of the sedimentary structures, and their evolution along the last 29 years(between 1984 and 2013). The major result highlights the presence of sorted bedforms maintained by the swell, migrating northeastward and associated with the recent discovery of punctual poleward current on the shelf. The seafloor morphology of the Capbreton Canyonhead located only 250 m off the coastline, has experienced significant changes between 1998 and 2013, nonetheless it oscillates around a position of equilibrium. Furthermore, the influence of the littoral drift on sediment transfer from the shelf to the canyon was demonstrated. Sedimentary and morphological evidences combined with numerical modelingattest to the feeding of the Capbreton canyon head with coastal sand supplied by the southward long shore drift under high-energy wave conditions.

Systematic review of research manuscripts is a common procedure in which research studies pertaining a particular field or domain are classified and structured in a methodological way. This process involves, between other steps, an extensive review and consolidation of scientific metrics and attributes of the manuscripts, such as citations, type or venue of publication. The extraction and mapping of relevant publication data, evidently, is a very laborious task if performed manually. Automation of such systematic mapping steps intend to reduce the human effort required and therefore can potentially reduce the time required for this process.The objective of this thesis is to automate the data extraction and mapping steps when systematically reviewing studies. The manual process is replaced by novel graph modelling techniques for effective knowledge representation, as well as novel machine learning techniques that aim to learn these representations. This eventually automates this process by characterising the publications on the basis of certain sub-properties and qualities that give the reviewer a quick high-level overview of each research study. The final model is a concept learner that predicts these sub-properties which in addition addresses the inherent concept-drift of novel manuscripts over time. Different models were developed and explored in this research study for the development of concept learner.Results show that: (1) Graph reasoning techniques which leverage the expressive power in modern graph databases are very effective in capturing the extracted knowledge in a so-called knowledge graph, which allows us to form concepts that can be learned using standard machine learning techniques like logistic regression, decision trees and neural networks etc. (2) Neural network models and ensemble models outperformed other standard machine learning techniques like logistic regression and decision trees based on the evaluation metrics. (3) The concept learner is able to detect and avoid concept drift by retraining the model. / Systematisk granskning av forskningsmanuskript är en vanlig procedur där forskningsstudier inom ett visst område klassificeras och struktureras på ett metodologiskt sätt. Denna process innefattar en omfattande granskning och sammanförande av vetenskapliga mätvärden och attribut för manuskriptet, såsom citat, typ av manuskript eller publiceringsplats. Framställning och kartläggning av relevant publikationsdata är uppenbarligen en mycket mödosam uppgift om den utförs manuellt. Avsikten med automatiseringen av processen för denna typ av systematisk kartläggning är att minska den mänskliga ansträngningen, och den tid som krävs kan på så sätt minskas. Syftet med denna avhandling är att automatisera datautvinning och stegen för kartläggning vid systematisk granskning av studier. Den manuella processen ersätts av avancerade grafmodelleringstekniker för effektiv kunskapsrepresentation, liksom avancerade maskininlärningstekniker som syftar till att lära maskinen dessa representationer. Detta automatiserar så småningom denna process genom att karakterisera publikationerna beserat på vissa subjektiva egenskaper och kvaliter som ger granskaren en snabb god översikt över varje forskningsstudie. Den slutliga modellen är ett inlärningskoncept som förutsäger dessa subjektiva egenskaper och dessutom behandlar den inneboende konceptuella driften i manuskriptet över tiden. Olika modeller utvecklades och undersöktes i denna forskningsstudie för utvecklingen av inlärningskonceptet. Resultaten visar att: (1) Diagrammatiskt resonerande som uttnytjar moderna grafdatabaser är mycket effektiva för att fånga den framställda kunskapen i en så kallad kunskapsgraf, och gör det möjligt att vidareutveckla koncept som kan läras med hjälp av standard tekniker för maskininlärning. (2) Neurala nätverksmodeller och ensemblemodeller överträffade andra standard maskininlärningstekniker baserat på utvärderingsvärdena. (3) Inlärningskonceptet kan detektera och undvika konceptuell drift baserat på F1-poäng och omlärning av algoritmen.

The management of Water Distribution Systems (WDSs) involves making decisions about various operations in the network, including the scheduling of pump operations and setting of disinfectant dosing rates. There are often conflicting objectives in making these operational decisions, such as minimising costs while maximising the quality of the water supplied. Hence, the operation of WDSs can be very difficult, and there is generally considerable scope to improve the operational efficiency of these systems by improving the associated decision making process. In order to achieve this goal, optimisation methods known as Genetic Algorithms (GAs) have been successfully adopted to assist in determining the best possible solutions to WDS optimisation problems for a number of years. Even though there has been extensive research demonstrating the potential of GAs for improving the design and operation of WDSs, the method has not been widely adopted in practice. There are a number of reasons that may contribute to this lack of uptake, including the following difficulties: (a) developing an appropriate fitness function that is a suitable description of the objective of the optimisation including all constraints, (b) making decisions that are required to select the most appropriate variant of the algorithm, (c) determining the most appropriate parameter settings for the algorithm, and (d) a reluctance of WDS operators to accept new methods and approaches. While these are all important considerations, the correct selection of GA parameter values is addressed in this thesis. Common parameters include population size, probability of crossover, and probability of mutation. Generally, the most suitable GA parameters must be found for each individual optimisation problem, and therefore it might be expected that the best parameter values would be related to the characteristics of the associated fitness function. The result from the work undertaken in this thesis is a complete GA calibration methodology, based on the characteristics of the optimisation problem. The only input required by the user is the time available before a solution is required, which is beneficial in the WDS operation optimisation application considered, as well as many others where computationally demanding model simulations are required. Two methodologies are proposed and evaluated in this thesis, one that considers the selection pressure based on the characteristics of the fitness function, and another that is derived from the time to convergence based on genetic drift, and therefore does not require any information about the fitness function characteristics. The proposed methodologies have been compared against other GA calibration methodologies that have been proposed, as well as typical parameter values to determine the most suitable method to determine the GA parameter values. A suite of test functions has been used for the comparison, including 20 complex mathematical optimisation problems with different characteristics, as well as realistic WDS applications. Two WDS applications have been considered: one that has previously been optimised in the literature, the Cherry Hills-Brushy Plains network; and a real case study located in Sydney, Australia. The optimisation problem for the latter case study is to minimise the pumping costs involved in operating the WDS, subject to constraints on the system, including minimum disinfectant concentrations. Of the GA calibration methods compared, the proposed calibration methodology that considered selection pressure determined the best solution to the problem, producing a 30% reduction in the electricity costs for the water utility operating the WDS. The comparison of the different calibration approaches demonstrates three main results: 1. that the proposed methodology produced the best results out of the different GA calibration methods compared; 2. that the proposed methodology can be applied in practice; and 3. that a correctly calibrated GA is very beneficial when solutions are required in a limited timeframe. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1325448 / Thesis (Ph.D.) - University of Adelaide, School of Civil, Environmental and Mining Engineering, 2008

Cette thèse est dédiée à l'étude de problèmes de couplage en espace entre différents modèles d'écoulements compressibles. Nous considérons des formulations monodimensionnelles où l'interface de couplage est mince, fixe et séparant deux régions de l'espace correspondant aux deux modèles à coupler. L'objectif de notre travail consiste à définir une condition de couplage à l'interface et à résoudre numériquement le problème de couplage muni de cette condition. Après un état de l'art non exhaustif sur le couplage de systèmes hyperboliques de lois de conservation, nous proposons une nouvelle formulation de condition de couplage basée sur l'ajout d'un terme source mesure agissant exactement sur l'interface de couplage. Nous supposons, dans un premier temps, que le poids associé à ce terme source est connu et constant. Deux solveurs de Riemann sont développés dont une approche par relaxation préservant les solutions équilibres du problème de couplage. Cette méthode par relaxation est reprise par la suite dans le cadre d'un problème d'optimisation sous contraintes pour déterminer un poids dynamique en temps selon différentes motivations de transmission à l'interface. Dans une seconde partie, nous développons un solveur de Riemann approché pour un modèle bifluide à deux pressions dans le cas d'un écoulement diphasique isentropique par phase. Le modèle en question a pour particularité de comprendre des termes non conservatifs que l'on réécrit alors sous la forme de termes sources mesures. L'approche par relaxation établie dans la partie précédente est alors étendue au cas du modèle bifluide, moyennant une estimation a priori des contributions non conservatives. Cette méthode nous permet, dans un dernier chapitre, de résoudre numériquement le problème de couplage interfacial entre un modèle bifluide à deux pressions et un modèle de drift-flux grâce à l'approche dite du modèle père.

<p>Slutet av 1990-talet var början till slutet för många IT-företag när den så kallade IT-bubblan började spricka. Gemensam nämnare för de företag som överlevde var att de hade en genomtänkt strategi med en stabil ägarstruktur, god ledning, trogna kunder och stabil omsättning. Sedan december 2007 har tendenser visats att Sverige är på väg in i en lågkonjunktur som kommer att hålla i sig under 2008 och 2009. Med lågkonjunkturen följer även en minskad vilja att konsumera vilket leder till svårare tider för företag. Mot denna bakgrund, samt ett befintligt intresse för strategiarbete i små företag, inleddes studien med följande problemformulering: Hur bör små företag i en tillväxt arbeta för att förebygga strategisk drift? Syftet för studien var att förstå hur små företag i tillväxt arbetar med kontinuerliga strategifrågor samt att presentera rekommendationer för att motverka strategisk drift till de undersökta företagen. Studien är huvudsakligen genomförd med en retroduktiv ansats där det empiriska materialet sammanställdes, analyserades samt utformades till rekommendationer vilka presenterades för respondenterna. Urvalet av respondenter utgörs av tre små företag med god tillväxt. Det material som erhölls ur den empiriska undersökningen tolkades utifrån förförståelsen och den teoretiska referensramen varvid en delvis hermeneutisk och delvis realistisk kunskapssyn användes. Studien är av kvalitativ karaktär och datainsamlingen genomfördes med hjälp av intervjuer. Genom en sammanställning av vedertagna teoretiska resonemang skapades en referensram på vilken en matris baserades. Avsikten med matrisen var att skapa ett verktyg vilket innefattar de interna och externa aspekter som påverkar den strategiska positionen för företag. Matrisen kan även tydliggöra för hur olika strategiska beslut påverkar företaget i relation till de långsiktiga strategiska målen. Med stöd av den empiriska undersökningen positionerades företagen i matrisen utifrån deras nuvarande arbetssätt. Positionen motiverades för respondenterna som också presenterades ett möjligt framtida scenario rörande hur framtiden skulle kunna se ut om med den utveckling företaget hade för närvarande. Därefter presenterades ett alternativt scenario vilket, utifrån undersökningen och analysen, representerade en önskvärd utveckling för företagen. Rekommendationerna mottogs positivt av respondenterna vilket tolkades som att matrisen fyllt sitt syfte och befäste tanken att använda matrisen för scenarioskapande.</p>

Ce travail est une analyse comparative du potentiel de certains types de fibres de bois issues de résidus de première transformation dans la fabrication des composites bois/thermoplastiques. Les fibres analysées proviennent des essences suivantes : le thuya occidental (Thuja occidentalis L.), le pin gris (Pinus banksiana Lamb) et l'épinette noire (Picea mariana (Mill.)). Les effets des facteurs suivants sur la performance des matériaux composites bois/thermoplastique ont été analysés : l'essence de bois, l'origine des fibres (fibres de duramen ou d'aubier), la taille des particules de bois, les proportions dans le mélange et les procédés de mise en forme (injection, extrusion et thermo-compression). L'effet de la variabilité spécifique de la surface des fibres de bois sur la qualité de l'interface bois/thermoplastique a été étudié grâce à la méthode spectroscopique infrarouge en réflectance diffuse à transformée de Fourier (DRIFT) et la spectroscopie des photoélectrons par rayon-X (XPS). Une concentration élevée de lignine et d'extractibles sur la surface des fibres a été présentée comme principal facteur qui inhibe l'établissement d'un lien entre l'agent de couplage à base d'anhydride et le bois. L'analyse du développement des fibres de bois, avant et au cours de leur mise en forme, a montré que la forme et la longueur des fibres sont réduites dépendamment des procédés utilisés et de l'essence. Une caractérisation mécanique dynamique des matériaux composites en question ainsi que l'effet des différents types de résidus ligno-cellulosiques sur la relaxation de la chaine moléculaire de la matrice thermoplastique, i.e. HDPE, a été investiguée. Le comportement rhéologique des matériaux composites bois/thermoplastique dans le domaine viscoélastique linéaire a été analysé à travers les modèles mécaniques analogiques.

<p>The concept of energy production through the fusion of two light nuclei has been studied since the 1950’s. One of the major problems that fusion scientists have encountered is the confinement of the hot ionised gas, i.e. the plasma, in which the fusion process takes place. The most common way to contain the plasma is by using at magnetic field configuration, in which the plasma takes a doughnut-like shape. Experimental devices of this kind are referred to as tokamaks. For the fusion process to proceed at an adequate rate, the temperature of the plasma must exceed 100,000,000C. Such a high temperature forces the plasma out of thermodynamical equilibrium which plasma tries to regain by exciting a number of turbulent processes. After successfully quenching the lager scale magnetohydrodynamic turbulence that may instantly disrupt the plasma, a smaller scale turbulence revealed itself. As this smaller scale turbulence behaved contrary to the common theory at the time, it was referred to as anomalous. This kind of turbulence does not directly threaten existents of the plasma, but it allows for a leakage of heat and particles which inhibits the fusion reactions. It is thus essential to understand the origin of anomalous turbulence, the transport it generates and most importantly, how to reduce it. Today it is believed that anomalous transport is due to drift-type waves driven by temperature and density inhomogeneities and the theoretical treatment of these waves is the topic of this thesis.</p><p>The first part of the thesis contains a rigorous analytical two-fluid treatment of drift waves driven solely by density inhomogeneities. Effects of the toroidal magnetic field configuration, the Landau resonance, a peaked diamagnetic frequency and a sheared rotation of the plasma have been taken into account. These effects either stabilise or destabilise the drift waves and to determine the net result on the drift waves requires careful analysis. To this end, dispersion relations have been obtained in various limits to determine when to expect the different effects to be dominant. The main result of this part is that with a large enough rotational shear, the drift waves will be quenched.</p><p>In the second part we focus on temperature effects and thus treat reactive drift waves, specifically ion temperature gradient and trapped electron modes. In fusion plasmas the α-particles, created as a by-product of the fusion process, transfer the better part of their energy to the electrons and hence the electron temperature is expected to exceed the ion temperature. In most experiments until today, the ion temperature is greater than the electron temperature and this have been proven to improve the plasma confinement. To predict the performance of future fusion plasmas, where the fusion process is ongoing, a comprehensive study of hot-electron plasmas and external heating effects have been carried out. Especially the stiffness (heat flux vs. inverse temperature length scale) of the plasma has been examined. This work was performed by simulations done with the JETTO code utilising the Weiland model. The outcome of these simulations shows that the plasma response to strong heating is very stiff and that the plasma energy confinement time seems to vary little in the hot-electron mode.</p>

<p>Behaviour occurs in time, and precise timing in the range of seconds and fractions of seconds is for most living organisms necessary for successful interaction with the environment. Our ability to time discrete actions and to predict events on the basis of prior events indicates the existence of an internal timing mechanism. The nature of this mechanism provides essential constraints on models of the functional organisation of the brain. </p><p>The present work indicates that there are discontinuities in the function of time close to 1 s and 1.4 s, both in the amount of drift in a series of produced intervals (Study I) and in the detectability of drift in a series of sounds (Study II). The similarities across different tasks further suggest that action and perceptual judgements are governed by the same (kind of) mechanism. Study III showed that series of produced intervals could be characterised by different amounts of positive fractal dependency related to the aforementioned discontinuities. </p><p>In conjunction with other findings in the literature, these results suggest that timing of intervals up to a few seconds is strongly dependent on previous intervals and on the duration to be timed. This argues against a clock-counter mechanism, as proposed by scalar timing theory, according to which successive intervals are random and the size of the timing error conforms to Weber's law. </p><p>A functional model is proposed, expressed in an autoregressive framework, which consists of a single-interval timer with error corrective feedback. The duration-specificity of the proposed model is derived from the order of error correction, as determined by a semi-flexible temporal integration span. </p>