Cette thèse est consacrée à l’étude mathématique des effets de désordre dans divers systèmes physiques. On commence par trois problèmes d’homogénéisation stochastique en lien avec des questions statiques de physique classique. Premièrement, en vue de la déduction rigoureuse de l’élasticité non-linéaire à partir de la physique statistique de réseaux de chaînes de polymères, on établit l’existence de propriétés effectives pour des matériaux hyperélastiques hétérogènes aléatoires sous des hypothèses générales de croissance. Deuxièmement, dans un cadre linéarisé simplifié, on étudie les formules de Clausius-Mossotti pour les propriétés effectives d’alliages binaires dilués: on donne la première preuve générale et rigoureuse de ces formules, ainsi qu’une extension aux ordres supérieurs. Troisièmement, encore pour des systèmes linéarisés, on propose d’étudier les déviations par rapport aux propriétés effectives et on établit la première théorie générale des fluctuations en homogénéisation stochastique. Dans la seconde partie de cette thèse, on se focalise sur la compétition entre désordre et interactions, et on étudie plus particulièrement la dynamique des vortex de Ginzburg-Landau dans des supraconducteurs 2D de type II en présence d’impuretés. Bien que la compréhension mathématique des propriétés vitreuses complexes de ces systèmes semble hors de portée, on établit rigoureusement la limite de champ moyen pour la dynamique d’un grand nombre de vortex, et on étudie l’homogénéisation de ces équations limites et leurs propriétés. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

This thesis represents a theoretical and numerical investigation of the canonical duality theory, which has been recently proposed as an alternative to the classic and direct methods for non-convex variational problems. These non-convex variational problems arise in a wide range of scientific and engineering applications, such as phase transitions, post-buckling of large deformed beam models, nonlinear field theory, and superconductivity. The numerical discretization of these non-convex variational problems leads to global minimization problems in a finite dimensional space. The primary goal of this thesis is to apply the newly developed canonical duality theory to two non-convex variational problems: a modified version of Ericksen's bar and a problem of Landau-Ginzburg type. The canonical duality theory is investigated numerically and compared with classic methods of numerical nature. Both advantages and shortcomings of the canonical duality theory are discussed. A major component of this critical numerical investigation is a careful sensitivity study of the various approaches with respect to changes in parameters, boundary conditions and initial conditions. / Ph. D.

Le but de ce travail est l'étude d'un problème de transmission en dynamique de population entre deux habitats juxtaposés. Dans chacun des habitats, on considère une équation aux dérivées partielles, modélisant la dispersion généralisée, formée par une combinaison linéaire du laplacien et du bilaplacien. On commence d'abord par étudier et résoudre la même équation avec diverses conditions aux limites posée dans un seul habitat. Cette étude est effectuée grâce à une formulation opérationnelle du problème: on réécrit cette EDP sous forme d'équation différentielle, posée dans un espace de Banach construit sur les espaces Lp avec 1 < p < +∞, où les coefficients sont des opérateurs linéaires non bornés. Grâce au calcul fonctionnel, à la théorie des semi-groupes analytiques et à la théorie de l'interpolation, on obtient des résultats optimaux d'existence, d'unicité et de régularité maximale de la solution classique si et seulement si les données sont dans certains espaces d'interpolation. / The aim of this work is the study of a transmission problem in population dynamics between two juxtaposed habitats. In each habitat, we consider a partial differential equation, modeling the generalized dispersion, made up of a linear combination of Laplacian and Bilaplacian operators. We begin by studying and solving the same equation with various boundary conditions in a single habitat. This study is carried out using an operational formulation of the problem: we rewrite this PDE as a differential equation, set in a Banach space built on the spaces Lp with 1 < p < +∞, where the coefficients are unbounded linear operators. Thanks to functional calculus, analytic semigroup theory and interpolation theory, we obtain optimal results of existence, uniqueness and maximum regularity of the classical solution if and only if the data are in some interpolation spaces.

The subject of this master's thesis called Family theme in Natalia Ginzburg's works is analysis of the chosen prosaic works of one of the biggest writers of the twentieth century, concentrated on the topic of the family. The introduction is a short presentation of the author (her biographical and bibliographical data). After that there is an analysis of her most known prosaic works with the family topic and with the topic of the relations in general. It is followed by more detailed analysis of her most known novel Lessico famigliare. In the final part, the work is concentrated on the biography of Manzoni's family in La famiglia Manzoni.

Made available in DSpace on 2014-06-11T19:24:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-03-16Bitstream added on 2014-06-13T20:32:36Z : No. of bitstreams: 1 nobrega_ds_me_mar.pdf: 2800420 bytes, checksum: 90bcb841f8ef8da74885d43e9cee6631 (MD5) / Esta pesquisa investiga como se dá a construção do conhecimento histórico - o que pressupõe a apreensão do conceito de tempo histórico - por alunos do ensino fundamental e médio de uma escola pública de Marília - SP. Por meio de uma dinâmica pedagógica dialógica e que utiliza a produção de filmes de animação quadro a quadro como base para a construção de discursos históricos pelos alunos, busca aliar o estudo da História às várias linguagens presentes na atualidade. Os diálogos estabelecidos nas aulas, diante de fontes históricas primárias e secundárias, são analisados de acordo com o conceito de circularidade cultural e pelo paradigma indiciário proposto por Carlo Ginzburg, cuja fonte teórica são os estudos da linguagem de Mickail Bakhtin. / The present research investigates how the construction of historic knowledge happens - what implies apprehending of the concept of historic time - by elementary and high school students of a public school in Marília, SP, Brazil. By means of a dialogical pedagogical dynamics, and using the production of stop motion pictures as the basis upon which the students construct historic speeches, it aims at enlacing the study of History and the numerous languages occurring at present. The dialogues established during classes, before primary and secondary historical sources, are analyzed according to the concept of cultural circularity and the sign's paradigm proposed by Carlo Ginzburg, whose theoretical sources are Mickail Bakhtin language studies.

This thesis considers the stability and transition of incompressible boundary layers. In particular, the Falkner–Skan–Cooke boundary layer subject to a cylindrical surface roughness, and the Blasius boundary layer with applied localized suction are investigated. These flows are of great importance within the aviation industry, feature complex transition scenarios, and are strongly three-dimensional in nature. Consequently, no assumptions regarding homogeneity in any of the spatial directions are possible, and the stability of the flow is governed by an extensive three-dimensional eigenvalue problem. The stability of these flows is addressed by high-order direct numerical simulations using the spectral element method, in combination with a Krylov subspace projection method. Such techniques target the long-term behavior of the flow and can provide lower limits beyond which transition is unavoidable. The origin of the instabilities, as well as the mechanisms leading to transition in the aforementioned cases are studied and the findings are reported. Additionally, a novel method for computing the optimal forcing of a dynamical system is developed. This type of analysis provides valuable information about the frequencies and structures that cause the largest energy amplification in the system. The method is based on the inverse power method, and is discussed in the context of the one-dimensional Ginzburg–Landau equation and a two-dimensional flow case governed by the Navier–Stokes equations. / <p>QC 20151015</p>

No description available.

L’art performance est un art contemporain difficile à définir. Néanmoins il peut se décrire par l’action d’un artiste de performance qui, à la différence du théâtre traditionnel, se présente lui-même devant un public, s’infligeant parfois de véritable blessure. Cet art questionne le « pour de vrai » et le « vrai ». En le comparant au théâtre il semble moins fictif car les blessures est le sang sont « vrais », et sa trace (captations vidéos, captations sonores, photographies, objets, croquis, écrits, etc.) le prouve. La fiction et la trace paraissent opposées, là où la première est une invention (le « pour de vrai ») l’autre est un élément pérenne d’une action vécue (le « vrai »), l’art performance permettrait alors de penser ces deux notions non plus comme opposés mais comme corrélatives. L’art performance présente sa trace comme un élément pérenne d’une action plus ou moins inventée : le « vrai » dont la frontière avec le « pour de vrai » peut être questionné. Cette thèse argumente ces hypothèses à travers une première partie comparative entre l’art performance et l’art théâtral, avec comme problématique la fiction qui semble opposée au « vrai ». Et une seconde partie corrélative sur le possible « pour de vrai » de la trace, qui permet l’étude de trois traces épistémologiques : la mémoire, l’écriture et l’indice à travers des exemples respectifs d’artistes de performance. / Performance art is a contemporary art is hard to define but which can be described as an action made an audience by a performance artist who, in contrast to the traditional theater, is the artist himself is inflicting sometimes real physical injuries. This art questions the 'like true' and the 'true' and seems less fictitious than traditional theater because blood’s physical injuries is 'true' and that he uses his trace as evidence (video recordings, sound recordings, photographs, objects, sketches, written, etc.). If the fiction and the trace seem opposed, because the first is an invention (the "like true") the other is a sustainable living action (the ' true') element, performance art then would think these two concepts not as opposites but as Horn related. As performance art, object of study here, presents his trail as a perennial element of a more or less invented action: as the 'true' including the border with the "like true" can be questioned. This thesis argues its assumptions through a comparative part between performance art and theatrical art, with as problematic fiction that seems opposite to 'true'. And a second consequential part on the possible "like true" of the trace, which allows the study of three epistemological traces : memory, writing, and trifle through respective examples of performance artists.

Sr₃Ru₂O₇ is a quasi-two-dimensional metal and has a paramagnetic ground state that is heavily renormalised by electron-electron correlations and magnetic exchange interactions. Inextricably linked to this renormalisation is the metamagnetism of Sr₃Ru₂O₇ - a rapid rise in uniform magnetisation over a narrow range of applied magnetic field. Knowledge of the zero-field physics is essential to any description of the metamagnetism. Light may be shed on the enigmatic ground state of Sr₃Ru₂O₇ by doping the crystal lattice with foreign cations: this is the primary purpose of the original research referred to in this thesis, in which studies of some of the electronic properties of crystals of cation-doped Sr₃Ru₂O₇ are reported. Single crystals of Sr₃(Ru[subscript(1-x)]Ti[subscript(x)])₂O₇ and Sr₃(Ru[subscript(1-x)]Cr[subscript(x)])₂O₇ have been synthesised in an image furnace and some of the properties of these crystals have been measured. Evidence that indicates the emergence of a spin density wave as a function of Ti-doping in Sr₃(Ru[subscript(1-x)]Ti[subscript(x)])₂O₇ is presented. Time-dependent magnetic irreversibility has been observed in samples of Sr₃(Ru[subscript(1-x)]Cr[subscript(x)])₂O₇, thus hinting at the involvement of the RKKY mechanism in these materials. Regarding cation doping out of the conducting RuO₂ planes, samples of (Sr[subscript(1-y)]La[subscript(y)])₃Ru₂O₇ have been grown and investigated. Both the Sommerfeld coefficient and the Fermi liquid A coefficient of (Sr[subscript(1-y)]La[subscript(y)])₃Ru₂O₇ are found to decrease as a function of y (0 ≤ y ≤ 0.02); these observations point towards a reduction in the thermodynamic mass of the Landau quasiparticles. Results from magnetoresistance and magnetisation measurements indicate that the metamagnetism of the (Sr[subscript(1-y)]La[subscript(y)])₃Ru₂O₇ series probably cannot be explained by a rigid band-shift model. Also, some aspects of these data imply that the metamagnetism cannot be fully accounted for by a spin fluctuation extension to the Ginzburg-Landau theory of uniform magnetisation.

Cette étude s’organise autour d’une articulation : celle entre un médium (la photographie), une ville (Beyrouth), et les événements qui ont marqué son passé récent. Le thème des rapports entre la photographie et l’histoire, avec la pluralité de sens qui le décrit, vient, en arrière-fond de ces questions, délimiter l’horizon de cette étude ; le lien entre voir et savoir, antiquement aux sources de la connaissance historique (Hartog, Loraux), en représente la ligne de fuite. En premier plan, la relation photographique et historienne à l’événement constitue l’objet de cette recherche dont le propos est d’identifier dans la photographie une référence à l’histoire considérée en tant qu’écriture. Concrètement, cet argument se déplie sur deux mouvements. Il exige, dans un premier temps, une série d’analyses théoriques visant à étudier le potentiel de connaissance et le caractère formel de la photographie en qualité de représentation événementielle. En partant des expérimentations des avant-gardes (Lugon, Baqué), jusqu’au jumelage entre la photographie et la presse, il s’agira de montrer la part de lisibilité qui appartient aux narrations photographiques (Barthes, Lavoie). Ensuite, on prendra en considération le travail opéré par l’historien lors de l’opération historiographique visant à produire, autour de l’événement, une représentation historique (de Certeau, Ricœur, Ginzburg). Outre faire ressortir le caractère de visibilité qui appartient à l’écriture historienne, ce passage sera aussi l’occasion de produire une étude comparée de la photographie et de l’histoire (Kracauer) autour de notions ponctuelles, comme celles d’empreinte, d’indice et de témoignage. Le moteur de ce premier mouvement est la notion d’événement. Abordée d’un point de vue phénoménologique (Zarader, Marion, Dastur, Diano), elle nous permettra d’observer la photographie et l’histoire d’après la génétique de leur construction. Finalement, Beyrouth et son histoire façonnées par les images constituent le cadre à l’intérieur duquel s’organise le deuxième mouvement. Les analyses des œuvres de Sophie Ristelhueber (Beyrouth photographies, 1984), Robert Frank (Come again, 1991) et Lamia Joreige (Beyrouth, autopsie d’une ville, 2010) sont conçues comme autant d’espaces dialogiques entre la photographie, l’épistémologie de l’histoire et les événements historiques qu’elles représentent. Le propos est de faire ressortir le basculement qu’elles mettent en scène : de la chronique vers l’écriture d’histoire. / This study focuses on the connection between a medium (photography), a city (Beyrouth), and the events that have marked its recent past. The theme of the relationship between photography and history, with the plurality of meanings that describes it, defines the scope of this study. The link between seeing and knowing, which in Antiquity was the root of historical knowledge (Hartog, Loraux), represents its vanishing point. The photographic and historical relationship with the event constitutes the purpose of this research, the aim of which is to identify in photography a reference to history considered as writing. The argument of this dissertation unfolds in two stages. The first stage requires a series of theoretical analyses, which aim at studying the knowledge potential and the formal nature of photography as a factual representation. Starting with the experimentation of the avant-gardes (Lugon, Braqué), and exploring the twinning of photography and the press, our goal will be to demonstrate the part of readability that belongs to the photographic narratives (Barthes, Lavoie). We will then take into consideration the work accomplished by the historian during the historiographic process, aiming at producing an historical representation of the event (de Certeau, Ricoeur, Ginzburg). In addition to emphasizing the characteristic of visibility, which belongs to historical writing, this will also provide the occasion to produce a comparative study of photography and history through particular notions such as imprint, sign, and evidence. The driving force behind this first part is the notion of event. Broached from the point of view of phenomenology (Zarader, Marion, Dastur, Diano), it will enable us to analyze photography and history according to the genetics of their construction. Beyrouth and its history, shaped by images, are the context in which the second stage is organized. The analysis of the works of Sophie Ristelhueber (Beyrouth photographies, 1984), Robert Frank (Come again, 1991), and Lamia Joreige (Beyrouth, autopsie d’une ville, 2010) are conceived as dialogical spaces between photography, the epistemology of history and the historical events that they represent. The aim is to emphasize the shift they present in moving from chronicle to the writing of history.