Literatura académica sobre el tema "Géométrie du cordon"
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Tesis sobre el tema "Géométrie du cordon"
Cassani, Davide. "Théorie des cordes, compactifications avec flux et géométrie généralisée". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2009. http://tel.archives-ouvertes.fr/tel-00409105.
Texto completoNous commençons en introduisant les outils mathématiques nécessaires: nous nous concentrons sur les structures SU(3)xSU(3) sur le fibré tangent généralisé T+T*, en analysant leurs déformations. Ensuite nous étudions la théorie de supergravité N=2 quadri-dimensionnelle définie par réduction des théories de type II sur des fonds à structure SU(3)xSU(3) avec flux généraux de NSNS et RR: nous établissons l'action bosonique complète, et nous montrons comment ces donées sont reliées au formalisme de la géométrie généralisée sur T+T*. En particulier, nous trouvons une expression géométrique pour le potentiel scalaire N=2. Puis nous nous concentrons sur les relations entre les descriptions à 10d et à 4d des fonds supersymétriques avec flux: nous dérivons les conditions de vide N=1 dans la théorie N=2 à 4d, ainsi que dans sa troncation N=1, et nous prouvons une correspondance précise avec les équations qui caractérisent les vides N=1 au niveau dix-dimensionnel. Nous terminons en présentant des exemples concrets, basés sur des espaces quotients avec structure SU(3). Nous établissons pour ces espaces la cohérence de la troncation basée sur l'invariance gauche, et nous explorons les vides de la théorie associée, en prenant en compte les corrections des boucles des cordes.
De, Felice Oscar. "Solutions avec flux et géométrie généralisée exceptionnelle". Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS041/document.
Texto completoThe main topic of this thesis are flux compactifications. Firstly, we study dimensional reductions of type II and eleven-dimensional supergravities using exceptional generalised geometry. We start by presenting the needed mathematical tools, focusing on G-structures and their extension to generalised geometry. Then, we move our focus on compactifications. In particular, we mainly focus on type IIA, building the version of exceptional generalised geometry adapted to such supergravity and finding the right deformations of generalised Lie derivative to accomodate the Romans mass. We describe the generalised Scherk-Schwarz method to find consistent truncation ansatze preserving the maximal amount of supersymmetry. We apply such a method to several examples of truncations on spheres, we reproduce the truncation ansatz on S6 and the embedding tensor leading to dyonically gauged ISO(7) supergravity in four dimensions. For spheres of dimension d = 2; 3; 4, we find an obstruction to have generalised parallelisations in massive theory, giving the evidence that maximally supersymmetric reductions might not exist. As further point, we study generalised calibrations on AdS backgrounds in type IIB and M-theory. We find these are described by Exceptional Sasaki-Einstein structures and we place the focus on the generalised Reeb vectors. The inequalities for the energy bound are derived by decomposing a _-symmetry condition and equivalently, bispinors in calibration conditions from existing literature. We explain how the closure of the calibration forms is related to the integrability conditions of the Exceptional Sasaki- Einstein structure, in particular for AdS space-filling or point-like branes. Doing so, we show that the form parts of the twisted vector structure in M-theory provides the expected generalised calibrations. The IIB case yields similar results
Wang, Zeya. "Robotisation de la fabrication additive par procédé arc-fil : Identification et amélioration de la commande". Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0068.
Texto completoAdditive manufacturing of metallic parts has gained significant popularity in recent years as an important technological solution for the production of complex parts. Among the different processes of metal additive manufacturing, the wire-arc additive manufacturing (WAAM) using CMT (Cold metal transfer) welding is taken for our study because of its high deposition rate, low cost of equipment and little loss of material (low spatter) during manufacturing. In the literature review, it can be noted that one of the most important problems that prevent the industrial application of the WAAM is the poor geometric accuracy of the manufactured parts due to the instability of the process and the lack of reliable control system to deal with irregularities during deposition. The focus of this work is to improve the stability and geometric performance of the process. In this work, an experimental system is implemented to robotize the process and to monitor the geometry of the deposited parts. The process is modeled by artificial neural networks and a control system is developed to regulate the geometry of the deposit and to reduce manufacturing errors. Furthermore, an improvement strategy is applied in order to reduce the geometric instabilities at the ends of the bead; an in-situ monitoring method is also developed to detect the internal defects of deposited parts
Andriot, David. "Solutions avec flux de la théorie des cordes sur tores twistés, et Géométrie Complexe Généralisée". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2010. http://tel.archives-ouvertes.fr/tel-00497172.
Texto completoBorot, Gaetan. "Quelques problèmes de géométrie énumérative, de matrices aléatoires, d'intégrabilité, étudiés via la géométrie des surfaces de Riemann". Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00625776.
Texto completoBorot, Gaëtan. "Quelques problèmes de géométrie énumérative, de matrices aléatoires, d'intégrabilité, étudiés via la géométrie des surfaces de Riemann". Thesis, Paris 11, 2011. http://www.theses.fr/2011PA112092/document.
Texto completoComplex analysis is a powerful tool to study classical integrable systems, statistical physics on the random lattice, random matrix theory, topological string theory, … All these topics share certain relations, called "loop equations" or "Virasoro constraints". In the simplest case, the complete solution of those equations was found recently : it can be expressed in the framework of differential geometry over a certain Riemann surface which depends on the problem : the "spectral curve". This thesis is a contribution to the development of these techniques, and to their applications.First, we consider all order large N asymptotics in some N-dimensional integrals coming from random matrix theory, or more generally from "log gases" problems. We shall explain how to use loop equations to establish those asymptotics in beta matrix models within a one cut regime. This can be applied in the study of large fluctuations of the maximum eigenvalue in beta matrix models, and lead us to heuristic predictions about the asymptotics of Tracy-Widom beta law to all order, and for all positive beta. Second, we study the interplay between integrability and loop equations. As a corollary, we are able to prove the previous prediction about the asymptotics to all order of Tracy-Widom law for hermitian matrices.We move on with the solution of some combinatorial problems in all topologies. In topological string theory, a conjecture from Bouchard, Klemm, Mariño and Pasquetti states that certain generating series of Gromov-Witten invariants in toric Calabi-Yau threefolds, are solutions of loop equations. We have proved this conjecture in the simplest case, where those invariants coincide with the "simple Hurwitz numbers". We also explain recent progress towards the general conjecture, in relation with our work. In statistical physics on the random lattice, we have solved the trivalent O(n) model introduced by Kostov, and we explain the method to solve more general statistical models.Throughout the thesis, the computation of some "generalized matrices integrals" appears to be increasingly important for future applications, and this appeals for a general theory of loop equations
Orsi, Francesco. "Etude des vides de la théorie des cordes avec flux". Paris 7, 2012. http://www.theses.fr/2012PA077025.
Texto completoThis thesis revolves around investigating some aspects of both supersymmetric and non- supersymmetric flux vacua of type II string theory. After providing the relevant definition of a vacuum in this setting, the framework of Generalized Complex Geometry is exposed: we review in particular the differential conditions for vacua in the presence of fluxes in this language, and we discuss their relation to integrabi-lity of the associated structures. We then survey a natural extension able to include the whole flux con¬tent into a geometrical picture, known as Exceptional Generalized Geometry. Fluxes are recovered in this context as a twisting of the Levi-Civita operator, from which a set of differential equations for the relevant algebraic structures is derived. These are carefully compared with the known supersymmetric constraints that a vacuum should satisfy in both cases of N =1,2 supersymmetries. Motivated by the application of the AdS/CFT correspondence with a reduced amount of supercharges, we obtain an effective five-dimensional supersymmetric theory, and we demonstrate in particular how a specific ansatz largely used in the string theory literature can be naturally embedded in it. We then investigate the su-pergravity dual to a metastable supersymmetry-breaking state by considering the most general first- order deformations of a supersymmetric solution, in order to single out the backreaction of anti-D2 branes. We conclude that unavoidable infrared singularities arise in view of the presence of anti-D2 branes per-turbing the underlying supersymmetric background
Pasqualini, Olivier. "Éléments finis stochastiques étendus pour le calcul en fatigue de joints soudés avec géométries aléatoires". Nantes, 2013. http://www.theses.fr/2013NANT2090.
Texto completoWelded joints are essential components for the construction of various fixed or floating structures. These elements are so important that we need to fully understand the fatigue process in order to foresee the structural behaviour under cyclic loading. The fatigue lifetime computation of a welded joint depends of various parameters such as the geometry of the structure. The stress concentration factor computation Kt is an efficient key parameter to model the fatigue lifetime. It has the advantage to link theoretical stress with the maximum value of local stresses and so with the fatigue lifetime thanks to S-N curves. In order to compute the Kt coefficient from real data and their uncertainties, some measurements along welded joints were realized by using a Non-Destructive Control device with laser process measurement. A statistical analysis of these measures were carried out to model the geometrical parameters by random variables and to identify their probability distribution. Kt-computation were performed by using eXtended Stochastic Finite Element Method; this computation method combines the Stochastic Finite Element Method, efficient to solve problems governed by random physical inputs, and the XFEM, efficient to implicitly define the domain geometry by using level-sets. In particular, we use a non-intrusive method of least-square computation to carry out, with a few numbers of random values, a Kt formulation defined on Polynomial Chaos base. From these results, an original semi-probabilistic model is suggested which introduces the geometrical parameters
Orantin, Nicolas. "Du développement topologique des modèles de matrices à la théorie des cordes topologiques : combinatoire de surfaces par la géométrie algébrique". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2007. http://tel.archives-ouvertes.fr/tel-00173162.
Texto completoje montre que pour un choix particulier des paramètres, ces objets peuvent être rendus invariants modulaires et sont solutions des équations d'anomalie holomorphe de la théorie de Kodaira-Spencer donnant un nouvel élément vers la preuve de la conjecture de Dijkgraaf-Vafa.
Bordalo, Pedro. "Cordes et champs antisymétriques dans des espaces-temps courbes". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2004. http://tel.archives-ouvertes.fr/tel-00008396.
Texto completoLibros sobre el tema "Géométrie du cordon"
Luis, Alvarez-Gaumé, Francaviglia M, Gherardelli F. 1925- y Centro internationale matematico estivo, eds. Global geometry and mathematical physics: Lectures given at the 2nd session of the Centro internazionale matematico estivo (C.I.M.E.) held at Montecatini Terme, Italy, July 4-12, 1988. Berlin: Springer-Verlag, 1990.
Buscar texto completoInternational Conference on Differential Geometrical Methods in Theoretical Physics (16th 1987 Como, Italy). Differential geometrical methods in theoretical physics. Dordrecht: Kluwer Academic Publishers, 1988.
Buscar texto completo(Editor), K. Bleuler y M. Werner (Editor), eds. Differential Geometrical Methods in Theoretical Physics (NATO Science Series C:). Springer, 1988.
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