Relevant bibliographies by topics / Largeur infinie

Academic literature on the topic 'Largeur infinie'

Author: Grafiati
Published: 7 July 2024

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Contents

  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers
  6. Reports

Journal articles on the topic "Largeur infinie":

1

Boczar, J., A. Dorobczynski, and J. Miakotoi. "Modèle de transfert et de diffusion de masse dans un écoulement, en présence de gradients de vitesse et de gradients du coefficient de diffusion turbulente." Revue des sciences de l'eau 5, no. 3 (April 12, 2005): 353–79. http://dx.doi.org/10.7202/705136ar.

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Le travail présente un modèle mathématique conceptuel de transfert et de diffusion de masse destiné à l'étude des migrations d'effluents en rivière. Ce modèle prend en compte l'existence d'écoulements cisaillés ainsi que la présence de gradients de diffusion turbulente. Il permet de calculer les champs de concentrations et les valeurs moyennes de concentration à travers toute section transversale de l'écoulement. La localisation et la taille relative du rejet sont respectées. L'influence des rives sur les processus de dispersion est prise en considération.Pour quantifier l'influence des berges, une relation est établie entre les concentrations calculées en écoulement de largeur infinie et les concentrations en écoulement d'extension limitée. La méthode utilisée est fondée sur l'emploi d'un champ de vitesse et d'un champ de coefficient de diffusion, symétriques par rapport à des lignes riveraines séparant le courant nul d'un courant fictif situé de part et d'autre de ces limites.Les résultats des tests du modèle mathématique, réalisés à l'aide du programme moniteur « Gradient 2 », sont présentés. Dans le cas d'écoulements cisaillés, on a constaté que la valeur moyenne de concentration d'effluent calculée au travers de sections transversales à l'écoulement n'était pas une quantité invariante tout au long de l'écoulement. Un gradient de vitesse négatif induit une augmentation de cette moyenne à mesure que l'on s'éloigne du rejet alors qu'un gradient positif produit l'effet inverse. Un gradient du coefficient de diffusion turbulente détermine un changement du profil de concentration à l'intérieur d'une section transversale donnée, sans en changer cependant la valeur moyenne. Un gradient négatif augmente la valeur maximale de la distribution des concentrations. Un gradient positif fait diminuer la valeur maximale en aplatissant l'allure du profil.Le modèle mathématique a ensuite été vérifié à l'aide d'un modèle physique. Un modèle réduit respectant les similitudes d'écoulement a été bâti. Les gradients de vitesse du fluide et les gradients du coefficient de diffusion étaient provoqués par l'introduction de tirants d'eau non uniformes dans chaque section transversale. Les mesures réalisées ont permis d'estimer les coefficients de diffusion turbulente.
2

Shen, Luming, Yiying Yu, and Yuxin Zhou. "A note on the largest digits in Lüroth expansion." International Journal of Number Theory 10, no. 04 (May 21, 2014): 1015–23. http://dx.doi.org/10.1142/s1793042114500122.

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It is well known that every x ∈ (0, 1] can be expanded into an infinite Lüroth series with the form of [Formula: see text] where dn(x) ≥ 2 and is called the nth digits of x for each n ≥ 1. In [Representations of Real Numbers by Infinite Series, Lecture Notes in Mathematics, Vol. 502 (Springer, New York, 1976)], Galambos showed that for Lebesgue almost all x ∈ (0, 1], [Formula: see text], where Ln(x) = max {d1(x), …, dn(x)} denotes the largest digit among the first n ones of x. In this paper, we consider the Hausdorff dimension of the set [Formula: see text] for any α ≥ 0.
3

Tiwana, Mazhar Hussain, Rab Nawaz, and Amer Bilal Mann. "Radiation of sound in a semi-infinite hard duct inserted axially into a larger infinite lined duct." Analysis and Mathematical Physics 7, no. 4 (November 12, 2016): 525–48. http://dx.doi.org/10.1007/s13324-016-0154-4.

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Büyükaksoy, A., and A. Demir. "Radiation of sound from a semi-infinite rigid duct inserted axially into a larger infinite tube with wall impedance discontinuity." ZAMM 86, no. 7 (July 3, 2006): 563–71. http://dx.doi.org/10.1002/zamm.200510262.

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Liu, Li, and Hairong Yuan. "Steady subsonic potential flows through infinite multi-dimensional largely-open nozzles." Calculus of Variations and Partial Differential Equations 49, no. 1-2 (November 6, 2012): 1–36. http://dx.doi.org/10.1007/s00526-012-0570-8.

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Černý, Radovan, and Vincent Favre-Nicolin. "FOX: A friendly tool to solve nonmolecular structures from powder diffraction." Powder Diffraction 20, no. 4 (December 2005): 359–65. http://dx.doi.org/10.1154/1.2135314.

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Structural characterization from powder diffraction of compounds not containing isolated molecules but three-dimensional infinite structure (alloys, intermetallics, framework compounds, extended solids) by direct space methods has been largely improved in the last 15 years. The success of the method depends very much on a proper modeling of the structure from building blocks. The modeling from larger building blocks improves the convergence of the global optimization algorithm by a factor of up to 10. However, care must be taken about the correctness of the building block, like its rigidity, deformation, bonding distances, and ligand identity. Dynamical occupancy correction implemented in the direct space program FOX has shown to be useful when merging excess atoms, and even larger building blocks like coordination polyhedra. It also allows joining smaller blocks into larger ones in the case when the connectivity was not a priori evident from the structural model. We will show in several examples of nonmolecular structures the effect of the modeling by correct structural units.
7

Macpherson, Dugald, Alan H. Mekler, and Saharon Shelah. "The number of infinite substructures." Mathematical Proceedings of the Cambridge Philosophical Society 109, no. 1 (January 1991): 193–209. http://dx.doi.org/10.1017/s0305004100069668.

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AbstractGiven a relational structure M and a cardinal λ < |M|, let øλ denote the number of isomorphism types of substructures of M of size λ. It is shown that if μ < λ are cardinals, and |M| is sufficiently larger than λ, then øμ ≤ øλ. A description is also given for structures with few substructures of given infinite cardinality.
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Demir, A., and Ö. Yanaz Çinar. "Propagation of sound in an infinite two-part duct carrying mean flow inserted axially into a larger infinite duct with wall impedance discontinuity." ZAMM 89, no. 6 (June 16, 2009): 454–65. http://dx.doi.org/10.1002/zamm.200800145.

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Antczak, Tadeusz. "Saddle point criteria in semi-infinite minimax fractional programming under (Φ,ρ)-invexity." Filomat 31, no. 9 (2017): 2557–74. http://dx.doi.org/10.2298/fil1709557a.

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Semi-infinite minimax fractional programming problems with both inequality and equality constraints are considered. The sets of parametric saddle point conditions are established for a new class of nonconvex differentiable semi-infinite minimax fractional programming problems under(?,?)-invexity assumptions. With the reference to the said concept of generalized convexity, we extend some results of saddle point criteria for a larger class of nonconvex semi-infinite minimax fractional programming problems in comparison to those ones previously established in the literature.
10

Wang, Tian-Yi, and Jiaojiao Zhang. "Low Mach number limit of steady flows through infinite multidimensional largely-open nozzles." Journal of Differential Equations 269, no. 3 (July 2020): 1863–903. http://dx.doi.org/10.1016/j.jde.2020.01.023.

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You might also be interested in the extended bibliographies on the topic 'Largeur infinie' for particular source types:
Journal articles Dissertations / Theses Books

Dissertations / Theses on the topic "Largeur infinie":

1

Hajjar, Karl. "A dynamical analysis of infinitely wide neural networks." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASM001.

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Durant la dernière décennie, les réseaux de neurones ont eu un succès retentissant dans de nombreuses tâches en pratique, cependant les arguments théoriques derrière ce succès restent insuffisants et une théorie mathématique appropriée pour étudier rigoureusement ces objets fait toujours défaut. Les limites des réseaux de neurones à largeur infinie sont récemment apparues comme une façon d'éclaircir certains aspects du problème. Dans cette thèse, nous étudions la limite des réseaux de neurones de largeur infinie avec une renormalisation particulière souvent dénommée ''champ moyen'' dans la littérature. La difficulté d'analyser les réseaux de neurones d'un point de vue théorique réside en partie dans la nature hautement non-linéaire de ces objets et dans l'énorme quantité de paramètres, ou poids (pouvant aller jusqu'à la centaine de milliards en pratique) qui interagissent lorsqu'ils sont mis à jour durant la descente de gradient. Nous examinons les trajectoires durant l'optimisation des réseaux de neurones de largeur infinie pendant la phase d'entraînement afin d'exhiber des propriétés de ces modèles dans certains cadres simples tels que les réseaux de neurones entièrement connectés avec une ou plusieurs couches cachées. Cette thèse traite de différents aspects de la dynamique d'optimisation des réseaux de neurones de largeur infinie: des méthodes pour rendre possible l'entraînement de ces modèles aux symétries qui peuvent émerger dans cette limite en passant par de nouveaux algorithmes d'optimisation qui adaptent le nombre de neurones à la volée durant la phase d'entraînement
Neural networks have had tremendous success in many practical tasks over the last decade, yet the theoretical reasons behind their performance are poorly understood and we lack a proper mathematical theory to rigorously study the properties of those objects. Infinite-width limits of neural networks have recently emerged as a way to shed light on some of the aspects of the problem. In this thesis, we study the infinite-width limit of networks of different depths under a particular scaling often referred to as the ''mean-field'' scaling in the literature. Part of the reason why neural networks are difficult to analyze from a theoretical standpoint is because they are highly non-linear and involve a huge amount of parameters, or weights, (up to hundreds of billions in practice) which interact as they are updated during gradient descent. We investigate the optimization trajectories of the infinite-width limit of neural networks during training in order to exhibit properties of those models in simple settings such as fully-connected networks with one or more hidden layers. This thesis focuses on different aspects of the optimization dynamics of networks in the infinite-width limit: from methods to enable training those models at arbitrary depths to the symmetry properties that can emerge in that limit as well as novel optimization algorithms which adapt the number of neurons in an on-line fashion during training
2

Mens, Irini-Eleftheria. "Learning regular languages over large alphabets." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAM052/document.

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L'apprentissage de langages réguliers est un sous-ensemble de l'apprentissage automatique qui s'est révélé utile dans de nombreux domaines tels que l'intelli-gence artificielle, les réseaux de neurones, l'exploration de données, la vérification, etc. De plus, l'intérêt dans les langages définis sur des alphabets infinis ou de grande taille est croissant au fil des années. Même si plusierurs propriétés et théories se généralisent à partir du cas fini, l'apprentissage de tels langages est une tâche difficile.En effet, dans ce contexte, l'application naïve des algorithmes d'apprentissage traditionnel n'est pas possible.Dans cette thèse, nous présentons un schéma algorithmique général pour l'ap-prentissage de langages définis sur des alphabets infinis ou de grande taille, comme par exemple des sous-ensembles bornés de N or R ou des vecteurs booléens de grandes dimensions. Nous nous restreignons aux classes de langages qui sont acceptés par des automates déterministes symboliques utilisant des prédicats pour définir les transitions, construisant ainsi une partition finie de l'alphabet pour chaque état.Notre algorithme d'apprentissage, qui est une adaptation du L* d'Angluin, combine l'apprentissage classique d'un automate par la caractérisation de ses états, avec l'apprentissage de prédicats statiques définissant les partitions de l'alphabet. Nous utilisons l'apprentissage incrémental avec la propriété que deux types de requêtes fournissent une information suffisante sur le langage cible. Les requêtes du premier type sont les requêtes d'adhésions, qui permettent de savoir si un mot proposé appartient ou non au langage cible. Les requêtes du second type sont les requêtes d'équivalence, qui vérifient si un automate proposé accepte le langage cible; dans le cas contraire, un contre-exemple est renvoyé.Nous étudions l'apprentissage de langages définis sur des alphabets infinis ou de grande tailles dans un cadre théorique et général, mais notre objectif est de proposer des solutions concrètes pour un certain nombre de cas particuliers. Ensuite, nous nous intéressons aux deux principaux aspects du problème. Dans un premier temps, nous supposerons que les requêtes d'équivalence renvoient toujours un contre-exemple minimal pour un ordre de longueur-lexicographique quand l'automate proposé est incorrect. Puis dans un second temps, nous relâchons cette hypothèse forte d'un oracle d'équivalence, et nous la remplaçons avec une hypothèse plus réaliste où l'équivalence est approchée par un test sur les requêtes qui utilisent un échantillonnage sur l'ensemble des mots. Dans ce dernier cas, ce type de requêtes ne garantit pas l'obtention de contre-exemples, et par conséquent de contre-exemples minimaux. Nous obtenons alors une notion plus faible d'apprent-issage PAC (Probably Approximately Correct), permettant l'apprentissage d'une approximation du langage cible.Tout les algorithmes ont été implémentés, et leurs performances, en terme de construction d'automate et de taille d'alphabet, ont été évaluées empiriquement
Learning regular languages is a branch of machine learning, which has been proved useful in many areas, including artificial intelligence, neural networks, data mining, verification, etc. On the other hand, interest in languages defined over large and infinite alphabets has increased in recent years. Although many theories and properties generalize well from the finite case, learning such languages is not an easy task. As the existing methods for learning regular languages depends on the size of the alphabet, a straightforward generalization in this context is not possible.In this thesis, we present a generic algorithmic scheme that can be used for learning languages defined over large or infinite alphabets, such as bounded subsets of N or R or Boolean vectors of high dimensions. We restrict ourselves to the class of languages accepted by deterministic symbolic automata that use predicates to label transitions, forming a finite partition of the alphabet for every state.Our learning algorithm, an adaptation of Angluin's L*, combines standard automaton learning by state characterization, with the learning of the static predicates that define the alphabet partitions. We use the online learning scheme, where two types of queries provide the necessary information about the target language. The first type, membership queries, answer whether a given word belongs or not to the target. The second, equivalence queries, check whether a conjectured automaton accepts the target language, a counter-example is provided otherwise.We study language learning over large or infinite alphabets within a general framework but our aim is to provide solutions for particular concrete instances. For this, we focus on the two main aspects of the problem. Initially, we assume that equivalence queries always provide a counter-example which is minimal in the length-lexicographic order when the conjecture automaton is incorrect. Then, we drop this ``strong'' equivalence oracle and replace it by a more realistic assumption, where equivalence is approximated by testing queries, which use sampling on the set of words. Such queries are not guaranteed to find counter-examples and certainly not minimal ones. In this case, we obtain the weaker notion of PAC (probably approximately correct) learnability and learn an approximation of the target language. All proposed algorithms have been implemented and their performance, as a function of automaton and alphabet size, has been empirically evaluated
3

Takisaka, Toru. "Large Scale Geometries of Infinite Strings." Kyoto University, 2018. http://hdl.handle.net/2433/232221.

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Mallik, Mohammed Tariqul Hassan. "Electromagnetic Field Exposure Reconstruction by Artificial Intelligence." Electronic Thesis or Diss., Université de Lille (2022-....), 2023. https://pepite-depot.univ-lille.fr/ToutIDP/EDENGSYS/2023/2023ULILN052.pdf.

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Le sujet de l'exposition aux champs électromagnétiques a fait l'objetd'une grande attention à la lumière du déploiement actuel du réseaucellulaire de cinquième génération (5G). Malgré cela, il reste difficilede reconstituer avec précision le champ électromagnétique dans unerégion donnée, faute de données suffisantes. Les mesures in situ sontd'un grand intérêt, mais leur viabilité est limitée, ce qui renddifficile la compréhension complète de la dynamique du champ. Malgré legrand intérêt des mesures localisées, il existe encore des régions nontestées qui les empêchent de fournir une carte d'exposition complète. Larecherche a exploré des stratégies de reconstruction à partird'observations provenant de certains sites localisés ou de capteursdistribués dans l'espace, en utilisant des techniques basées sur lagéostatistique et les processus gaussiens. En particulier, desinitiatives récentes se sont concentrées sur l'utilisation del'apprentissage automatique et de l'intelligence artificielle à cettefin. Pour surmonter ces problèmes, ce travail propose de nouvellesméthodologies pour reconstruire les cartes d'exposition aux CEM dans unezone urbaine spécifique en France. L'objectif principal est dereconstruire des cartes d'exposition aux ondes électromagnétiques àpartir de données provenant de capteurs répartis dans l'espace. Nousavons proposé deux méthodologies basées sur l'apprentissage automatiquepour estimer l'exposition aux ondes électromagnétiques. Pour la premièreméthode, le problème de reconstruction de l'exposition est défini commeune tâche de traduction d'image à image. Tout d'abord, les données ducapteur sont converties en une image et l'image de référencecorrespondante est générée à l'aide d'un simulateur basé sur le tracédes rayons. Nous avons proposé un réseau adversarial cGAN conditionnépar la topologie de l'environnement pour estimer les cartes d'expositionà l'aide de ces images. Le modèle est entraîné sur des images de cartesde capteurs tandis qu'un environnement est donné comme entréeconditionnelle au modèle cGAN. En outre, la cartographie du champélectromagnétique basée sur le Generative Adversarial Network estcomparée au simple Krigeage. Les résultats montrent que la méthodeproposée produit des estimations précises et constitue une solutionprometteuse pour la reconstruction des cartes d'exposition. Cependant,la production de données de référence est une tâche complexe car elleimplique la prise en compte du nombre de stations de base actives dedifférentes technologies et opérateurs, dont la configuration du réseauest inconnue, par exemple les puissances et les faisceaux utilisés parles stations de base. En outre, l'évaluation de ces cartes nécessite dutemps et de l'expertise. Pour répondre à ces questions, nous avonsdéfini le problème comme une tâche d'imputation de données manquantes.La méthode que nous proposons prend en compte l'entraînement d'un réseauneuronal infini pour estimer l'exposition aux champs électromagnétiques.Il s'agit d'une solution prometteuse pour la reconstruction des cartesd'exposition, qui ne nécessite pas de grands ensembles d'apprentissage.La méthode proposée est comparée à d'autres approches d'apprentissageautomatique basées sur les réseaux UNet et les réseaux adversairesgénératifs conditionnels, avec des résultats compétitifs
The topic of exposure to electromagnetic fields has received muchattention in light of the current deployment of the fifth generation(5G) cellular network. Despite this, accurately reconstructing theelectromagnetic field across a region remains difficult due to a lack ofsufficient data. In situ measurements are of great interest, but theirviability is limited, making it difficult to fully understand the fielddynamics. Despite the great interest in localized measurements, thereare still untested regions that prevent them from providing a completeexposure map. The research explored reconstruction strategies fromobservations from certain localized sites or sensors distributed inspace, using techniques based on geostatistics and Gaussian processes.In particular, recent initiatives have focused on the use of machinelearning and artificial intelligence for this purpose. To overcome theseproblems, this work proposes new methodologies to reconstruct EMFexposure maps in a specific urban area in France. The main objective isto reconstruct exposure maps to electromagnetic waves from some datafrom sensors distributed in space. We proposed two methodologies basedon machine learning to estimate exposure to electromagnetic waves. Forthe first method, the exposure reconstruction problem is defined as animage-to-image translation task. First, the sensor data is convertedinto an image and the corresponding reference image is generated using aray tracing-based simulator. We proposed an adversarial network cGANconditioned by the environment topology to estimate exposure maps usingthese images. The model is trained on sensor map images while anenvironment is given as conditional input to the cGAN model.Furthermore, electromagnetic field mapping based on the GenerativeAdversarial Network is compared to simple Kriging. The results show thatthe proposed method produces accurate estimates and is a promisingsolution for exposure map reconstruction. However, producing referencedata is a complex task as it involves taking into account the number ofactive base stations of different technologies and operators, whosenetwork configuration is unknown, e.g. powers and beams used by basestations. Additionally, evaluating these maps requires time andexpertise. To answer these questions, we defined the problem as amissing data imputation task. The method we propose takes into accountthe training of an infinite neural network to estimate exposure toelectromagnetic fields. This is a promising solution for exposure mapreconstruction, which does not require large training sets. The proposedmethod is compared with other machine learning approaches based on UNetnetworks and conditional generative adversarial networks withcompetitive results
5

Federici, Bruno. "Interactions between large-scale invariants in infinite graphs." Thesis, University of Warwick, 2017. http://wrap.warwick.ac.uk/108882/.

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This thesis is devoted to the study of a number of properties of graphs. Our first main result clarifies the relationship between hyperbolicity and non-amenability for plane graphs of bounded degree. This generalises a known result for Cayley graphs to bounded degree graphs. The second main result provides a counterexample to a conjecture of Benjamini asking whether a transient, hyperbolic graph must have a transient subtree. In Chapter 4 we endow the set of all graphs with two pseudometrics and we compare metric properties arising from each of them. The two remaining chapters deal with bi-infinite paths in Z2 and geodetic Cayley graphs.
6

Winterfeld, Anton. "Large-scale semi-infinite optimization applied to industrial gemstone cutting." Berlin dissertation.de, 2007. http://www.dissertation.de/buch.php3?buch=5290.

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Maroulas, Vasileios Budhiraja Amarjit. "Small noise large deviations for infinite dimensional stochastic dynamical systems." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2008. http://dc.lib.unc.edu/u?/etd,1779.

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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2008.
Title from electronic title page (viewed Sep. 16, 2008). " ... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Statistics and Operations Research Statistics." Discipline: Statistics and Operations Research; Department/School: Statistics and Operations Research.
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He, Ruojun. "Square Coded Aperture: A Large Aperture with Infinite Depth of Field." University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1418078808.

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Pontes, Duff Pereira Igor. "Approximation des systèmes dynamiques à grande dimension et à dimension infinie." Thesis, Toulouse, ISAE, 2017. http://www.theses.fr/2017ESAE0001/document.

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Dans le domaine de l’ingénierie (par exemple l’aéronautique, l’automobile, la biologie, les circuits), les systèmes dynamiques sont le cadre de base utilisé pour modéliser, contrôler et analyser une grande variété de systèmes et de phénomènes. En raison de l’utilisation croissante de logiciels dédiés de modélisation par ordinateur, la simulation numérique devient de plus en plus utilisée pour simuler un système ou un phénomène complexe et raccourcir le temps de développement et le coût. Cependant, le besoin d’une précision de modèle améliorée conduit inévitablement à un nombre croissant de variables et de ressources à gérer au prix d’un coût numérique élevé. Cette contrepartie justifie la réduction du modèle. Pour les systèmes linéaires invariant dans le temps, plusieurs approches de réduction de modèle ont été effectivement développées depuis les années 60. Parmi celles-ci, les méthodes basées sur l’interpolation se distinguent par leur souplesse et leur faible coût de calcul, ce qui en fait un candidat prédestiné à la réduction de systèmes véritablement à grande échelle. Les progrès récents démontrent des façons de trouver des paramètres de réduction qui minimisent localement la norme H2 de l’erreur d’incompatibilité. En général, une approximation d’ordre réduit est considérée comme un modèle de dimension finie. Cette représentation est assez générale et une large gamme de systèmes dynamiques linéaires peut être convertie sous cette forme, du moins en principe. Cependant, dans certains cas, il peut être plus pertinent de trouver des modèles à ordre réduit ayant des structures plus complexes. A titre d’exemple, certains systèmes de phénomènes de transport ont leurs valeurs singulières Hankel qui se décomposent très lentement et ne sont pas facilement approchées par un modèle de dimension finie. En outre, pour certaines applications, il est intéressant de disposer d’un modèle structuré d’ordre réduit qui reproduit les comportements physiques. C’est pourquoi, dans cette thèse, les modèles à ordre réduit ayant des structures de retard ont été plus précisément considérés. Ce travail a consisté, d’une part, à développer de nouvelles techniques de réduction de modèle pour des modèles à ordre réduit avec des structures de retard et, d’autre part, à trouver de nouvelles applications d’approximation de modèle. La contribution majeure de cette thèse couvre les sujets d’approximation et inclut plusieurs contributions au domaine de la réduction de modèle. Une attention particulière a été accordée au problème de l’approximation du modèle optimale pour les modèles structurés retardés. À cette fin, de nouveaux résultats théoriques et méthodologiques ont été obtenus et appliqués avec succès aux repères académiques et industriels. De plus, la dernière partie de ce manuscrit est consacrée à l’analyse de la stabilité des systèmes retardés par des méthodes interpolatoires. Certaines déclarations théoriques ainsi qu’une heuristique sont développées permettant d’estimer de manière rapide et précise les diagrammes de stabilité de ces systèmes
In the engineering area (e.g. aerospace, automotive, biology, circuits), dynamical systems are the basic framework used for modeling, controlling and analyzing a large variety of systems and phenomena. Due to the increasing use of dedicated computer-based modeling design software, numerical simulation turns to be more and more used to simulate a complex system or phenomenon and shorten both development time and cost. However, the need of an enhanced model accuracy inevitably leads to an increasing number of variables and resources to manage at the price of a high numerical cost. This counterpart is the justification for model reduction. For linear time-invariant systems, several model reduction approaches have been effectively developed since the 60’s. Among these, interpolation-based methods stand out due to their flexibility and low computational cost, making them a predestined candidate in the reduction of truly large-scale systems. Recent advances demonstrate ways to find reduction parameters that locally minimize the H2 norm of the mismatch error. In general, a reduced-order approximation is considered to be a finite dimensional model. This representation is quite general and a wide range of linear dynamical systems can be converted in this form, at least in principle. However, in some cases, it may be more relevant to find reduced-order models having some more complex structures. As an example, some transport phenomena systems have their Hankel singular values which decay very slowly and are not easily approximated by a finite dimensional model. In addition, for some applications, it is valuable to have a structured reduced-order model which reproduces the physical behaviors. That is why, in this thesis, reduced-order models having delay structures have been more specifically considered. This work has focused, on the one hand, in developing new model reduction techniques for reduced order models having delay structures, and, on the other hand, in finding new applications of model approximation. The major contribution of this thesis covers approximation topics and includes several contributions to the area of model reduction. A special attention was given to the H2 optimal model approximation problem for delayed structured models. For this purpose, some new theoretical and methodological results were derived and successfully applied to both academic and industrial benchmarks. In addition, the last part of this manuscript is dedicated to the analysis of time-delayed systems stability using interpolatory methods. Some theoretical statements as well as an heuristic are developed enabling to estimate in a fast and accurate way the stability charts of those systems
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Xu, Tiange. "Large deviations and invariant measures for stochastic partial differential equations in infinite dimensions." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.496642.

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This thesis consists of two parts. We start with some background theory that will be used throughout the thesis. Then, in the first part, we investigate the invariant measures of stochastic evolution equations of pure jump type and obtain a characterization of invariant measures. As an application, it is shown that the equation has a unique invariant probability measure under some reasonable conditions.
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Books on the topic "Largeur infinie":

1

Danielle, Steel. Une grâce infinie. Paris: Pocket, 2010.

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Danielle, Steel. Une grâce infinie. Paris: Éd. France loisirs, 2010.

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Danielle, Steel. Une grâce infinie: Roman. Paris: Presses de la Cité, 2009.

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Yancey, Rick. The infinite sea. New York, New York: Speak, an imprint of Penguin Random House LLC, 2015.

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Auchincloss, Louis. Her infinite variety. Boston: Houghton Mifflin, 2000.

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Auchincloss, Louis. Her infinite variety. Boston: Houghton Mifflin, 2000.

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Auchincloss, Louis. Her infinite variety. Thorndike, Me: G.K. Hall, 2001.

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Close, F. E. The infinity puzzle. Oxford: Oxford University Press, 2011.

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Kanamori, Akihiro. The higher infinite: Large cardinals in set theory from their beginnings. 2nd ed. Berlin: Springer, 2003.

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Kanamori, Akihiro. The higher infinite: Large cardinals in set theory from their beginnings. 2nd ed. Berlin: Springer, 1997.

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Book chapters on the topic "Largeur infinie":

1

Silbermann, Bernd. "Infinite Matrices." In Introduction to Large Truncated Toeplitz Matrices, 1–30. New York, NY: Springer New York, 1999. http://dx.doi.org/10.1007/978-1-4612-1426-7_1.

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Rosenberg, Arnold L., and Denis Trystram. "The Vertigo of Infinity: Handling the Very Large and the Infinite." In Understand Mathematics, Understand Computing, 215–32. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-58376-7_7.

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Pérez-Abreu, Victor, and Constantin Tudor. "Large Deviations for Double Itô Equations." In Stochastics in Finite and Infinite Dimensions, 379–99. Boston, MA: Birkhäuser Boston, 2001. http://dx.doi.org/10.1007/978-1-4612-0167-0_20.

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Macpherson, Dugald. "Large Subgroups of Infinite Symmetric Groups." In Finite and Infinite Combinatorics in Sets and Logic, 249–78. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-2080-7_18.

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Atanasova, Nataliya, and Iliya Brayanov. "Computation of Some Unsteady Flows over Porous Semi-infinite Flat Surface." In Large-Scale Scientific Computing, 621–28. Berlin, Heidelberg: Springer Berlin Heidelberg, 2006. http://dx.doi.org/10.1007/11666806_71.

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Stauffer, D. "Surface Simulations for Large Eden Clusters." In Percolation Theory and Ergodic Theory of Infinite Particle Systems, 301–9. New York, NY: Springer New York, 1987. http://dx.doi.org/10.1007/978-1-4613-8734-3_17.

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Egidi, Michela, Ivica Nakić, Albrecht Seelmann, Matthias Täufer, Martin Tautenhahn, and Ivan Veselić. "Null-controllability and control cost estimates for the heat equation on unbounded and large bounded domains." In Control Theory of Infinite-Dimensional Systems, 117–57. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-35898-3_5.

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Lykina, Valeriya. "Existence Theorem for Infinite Horizon Optimal Control Problems with Mixed Control-State Isoperimetrical Constraint." In Large-Scale Scientific Computing, 228–36. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-73441-5_24.

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Lette, Danya, and Azadeh Farzan. "Commutativity for Concurrent Program Termination Proofs." In Computer Aided Verification, 109–31. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-37706-8_6.

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AbstractThis paper explores how using commutativity can improve the efficiency and efficacy of algorithmic termination checking for concurrent programs. If a program run is terminating, one can conclude that all other runs equivalent to it up-to-commutativity are also terminating. Since reasoning about termination involves reasoning about infinite behaviours of the program, the equivalence class for a program run may include infinite words with lengths strictly larger than $$\omega $$ ω that capture the intuitive notion that some actions may soundly be postponed indefinitely. We propose a sound proof rule which exploits these as well as classic bounded commutativity in reasoning about termination, and devise a way of algorithmically implementing this sound proof rule. We present experimental results that demonstrate the effectiveness of this method in improving automated termination checking for concurrent programs.
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Hinderer, Karl, Ulrich Rieder, and Michael Stieglitz. "Markovian Decision Processes with Large and with Infinite Horizon." In Universitext, 347–52. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-48814-1_20.

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Conference papers on the topic "Largeur infinie":

1

Soni, Bhanu Pratap, Vikas Gupta, Rajesh Kumar, Akash Saxena, and S. L. Surana. "Application of ANN for stability assessment of large power system by post-fault rotor angle measurements." In 2018 IEEMA Engineer Infinite Conference (eTechNxT). IEEE, 2018. http://dx.doi.org/10.1109/etechnxt.2018.8385363.

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Khoussainov, Bakh, and Toru Takisaka. "Large scale geometries of infinite strings." In 2017 32nd Annual ACM/IEEE Symposium on Logic in Computer Science (LICS). IEEE, 2017. http://dx.doi.org/10.1109/lics.2017.8005078.

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Ohannessian, Mesrob I., and Munther A. Dahleh. "Large alphabets: Finite, infinite, and scaling models." In 2012 46th Annual Conference on Information Sciences and Systems (CISS). IEEE, 2012. http://dx.doi.org/10.1109/ciss.2012.6310941.

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Nandakumar, K., Pankaj Wahi, and Anindya Chatterjee. "Infinite Dimensional Slow Modulations in a Delayed Model for Orthogonal Cutting Vibrations." In ASME 2008 9th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2008. http://dx.doi.org/10.1115/esda2008-59339.

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We apply the method of multiple scales (MMS) to a well known model of regenerative cutting vibrations in the large delay regime. By “large” we mean the delay is much larger than the time scale of typical cutting tool oscillations. The MMS upto second order for such systems has been developed recently, and is applied here to study tool dynamics in the large delay regime. The second order analysis is found to be much more accurate than first order analysis. Numerical integration of the MMS slow flow is much faster than for the original equation, yet shows excellent accuracy. The main advantage of the present analysis is that infinite dimensional dynamics is retained in the slow flow, while the more usual center manifold reduction gives a planar phase space. Lower-dimensional dynamical features, such as Hopf bifurcations and families of periodic solutions, are also captured by the MMS. Finally, the strong sensitivity of the dynamics to small changes in parameter values is seen clearly.
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Plecnik, Mark M., and Ronald S. Fearing. "Finding Only Finite Roots to Large Kinematic Synthesis Systems." In ASME 2016 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/detc2016-60428.

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In this work, a new method is introduced for solving large polynomial systems for the kinematic synthesis of linkages. The method is designed for solving systems with degrees beyond 100,000, which often are found to possess a number of finite roots that is orders of magnitude smaller. Current root-finding methods for large polynomial systems discover both finite and infinite roots, although only finite roots have meaning for engineering purposes. Our method demonstrates how all infinite roots can be avoided in order to obtain substantial computational savings. Infinite roots are avoided by generating random linkage dimensions to construct start-points and start-systems for homotopy continuation paths. The method is benchmarked with a four-bar path synthesis problem.
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San Andre´s, Luis, and Tae Ho Kim. "Gas Foil Bearings: Limits for High-Speed Operation." In World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-63398.

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Commercial oil-free micro turbomachinery relies on gas foil bearings (GFBs) for reliable performance with improved efficiency. However, GFB modeling is still largely empirical, lacking experimental validation. An analysis of simple GFBs operating at large shaft speeds (infinite speed number) follows. The bearing ultimate load and stiffness coefficients are derived from simple algebraic equations for the gas film pressures at the equilibrium journal position and due to small amplitude journal motions, respectively. GFBs without a clearance or with assembly interference are easily modeled. The underlying elastic structure (bump foil strip) determines the ultimate load capacity of a GFB as well as its stiffnesses, along with the limiting journal displacement and structural deformation. Thus, an accurate estimation of the actual minimum film thickness is found prior to performing calculations with a complex computational model, even for the case of large loads that result in a journal eccentricity well exceeding the nominal clearance, if applicable. An initial assembly preload (interference between shaft and foil) increases the GFB static stiffness at both null and infinite rotor speeds. At infinite speed, cross-coupled stiffnesses are nil; and thus, GFBs are impervious to hydrodynamic whirl instability.
7

Cipolla, Jeffrey L. "Transient Infinite Elements for Acoustics and Shock." In ASME 1995 Design Engineering Technical Conferences collocated with the ASME 1995 15th International Computers in Engineering Conference and the ASME 1995 9th Annual Engineering Database Symposium. American Society of Mechanical Engineers, 1995. http://dx.doi.org/10.1115/detc1995-0400.

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Abstract Many phenomena in acoustically loaded structural vibrations are better understood in the time domain, particularly transient radiation, shock, and problems involving nonlinearities and bulk structural motion. In addition, the geometric complexity of structures of interest drives the analyst toward domain-discretized solution methods, such as finite elements or finite differences, and large numbers of degrees of freedom. In such methods, efficient numerical enforcement of the Sommerfeld radiation condition in the time domain becomes difficult; although a great many methodologies for doing so have been demonstrated, there seems to exist no consensus on the optimal numerical implementation of this boundary condition in the time domain. Here, we present theoretical development of several new boundary operators for conventional finite element codes. Each proceeds from successful domain-discretised, projected field-type harmonic solutions, in contrast to boundary integral equation operators or those derived from algebraic functions. We exploit the separable prolate-spheroidal coordinate system, which is sufficiently general for a large variety of problems of naval interest, to obtain finite element-like operators (matrices) for the boundary points. Use of this coordinate system results in element matrices that can be analytically inverse transformed from the frequency to the time domain, using appropriate approximations, without altering the Hilbert space in which the approximate solution resides. The inverse transformation introduces some additional theoretical issues involving time delays and Stieltjes-type integrals, which are easily resolved. In addition, use of element-like boundary operators does not alter the banded structure of the system matrices, which is of enormous importance for efficient solution of large problems. Results presented here include theoretical derivation of the new “infinite elements”, the approximations for certain problematic frequency-domain terms, resolution of the inversion issues, and element matrices for the boundary operators which introduce no new continuity requirements on the fluid field variable.
8

Vaswani, N. "Particle Filters for Infinite (or Large) Dimensional State Spaces-Part 2." In 2006 IEEE International Conference on Acoustics, Speech, and Signal Processing. IEEE, 2006. http://dx.doi.org/10.1109/icassp.2006.1660583.

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MOYANO, LUIS G., ANA P. MAJTEY, and CONSTANTINO TSALLIS. "WEAK CHAOS IN LARGE CONSERVATIVE SYSTEM – INFINITE-RANGE COUPLED STANDARD MAPS." In Proceedings of the 31st Workshop of the International School of Solid State Physics. WORLD SCIENTIFIC, 2005. http://dx.doi.org/10.1142/9789812701558_0013.

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Mistry, Vinan, Gary Page, and James McGuirk. "Large Eddy Simulation of Crossflow Vortices on an Infinite Swept Wing." In 42nd AIAA Fluid Dynamics Conference and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2012. http://dx.doi.org/10.2514/6.2012-2694.

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Reports on the topic "Largeur infinie":

1

Budhiraja, Amarjit, Paul Dupuis, and Vasileios Maroulas. Large Deviations for Infinite Dimensional Stochastic Dynamical Systems. Fort Belvoir, VA: Defense Technical Information Center, March 2007. http://dx.doi.org/10.21236/ada476159.

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