Tesi: "Degenerate PDE"

1

Hatami, Farhad. "Configurations of Wardrop's equilibrium and application to traffic analysis". Doctoral thesis, Universitat Autònoma de Barcelona, 2018. http://hdl.handle.net/10803/565891.

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This thesis consists of two parts, and the connection between them is the so-called Wardrop's equilibrium. In the rst part of this thesis, which is the theoretical part, we study the congested transport dynamics arising from a non-autonomous tra c optimization problem. In this setting, we prove one can nd an optimal tra c strategy with support on the trajectories of a DiPerna-Lions ow. The proof follows the scheme introduced by Brasco, Carlier and Santambrogio in the autonomous setting, applied to the case of supercritical Sobolev dependence in the spatial variable. This requires both Lipschitz and weighted Sobolev apriori bounds for the minimizers of a class of integral functionals whose ellipticity bounds are satis ed only away from a ball of the gradient variable. We are then able to nd the con guration of Wardrop's equilibrium. In the second part of this thesis, which is the practical part, we use the established Wardrop's equi- librium in the theoretical section, in order to optimize the tra c problem in rel-life application. New OD demand problem formulation is explored which allows the modeler to de ne structural similarity between the historical and estimated OD matrix while ensuring computationally fast and tractable solution. Shrinkage regression methods, such as Ridge and Lasso regression, are proposed to de ne distance function between historical and estimated OD matrix, in order to minimize estimation vari- ance, and ensure the estimated OD matrix is close to true value. The presented OD estimation models reduce dimensionality of the OD demand vector, which is crucial when the dimensionality of OD ma- trix is high, due to high level of zoning system. A new solution approach based on the well-known gradient descent algorithm is applied to solve the proposed models. Finally, results are tested out on a real life-size network.

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2

Gerencsér, Máté. "Stochastic PDEs with extremal properties". Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/20445.

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We consider linear and semilinear stochastic partial differential equations that in some sense can be viewed as being at the "endpoints" of the classical variational theory by Krylov and Rozovskii [25]. In terms of regularity of the coeffcients, the minimal assumption is boundedness and measurability, and a unique L2- valued solution is then readily available. We investigate its further properties, such as higher order integrability, boundedness, and continuity. The other class of equations considered here are the ones whose leading operators do not satisfy the strong coercivity condition, but only a degenerate version of it, and therefore are not covered by the classical theory. We derive solvability in Wmp spaces and also discuss their numerical approximation through finite different schemes.

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3

Grundling, Hendrik. "Algebraic structure of degenerate systems /". Title page, table of contents and summary only, 1986. http://web4.library.adelaide.edu.au/theses/09PH/09phg888.pdf.

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4

Moss, Jonathan. "Linear degeneracy in multidimensions". Thesis, Loughborough University, 2016. https://dspace.lboro.ac.uk/2134/20171.

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Linear degeneracy of a PDE is a concept that is related to a number of interesting geometric constructions. We first take a quadratic line complex, which is a three parameter family of lines in projective space P3 specified by a single quadratic relation in the Plucker coordinates. This complex supplies us with a conformal structure in P3. With this conformal structure, we associate a three-dimensional second order quasilinear wave equation. We show that any PDE arising in this way is linearly degenerate, furthermore, any linearly degenerate PDE can be obtained by this construction. We classify Segre types of quadratic complexes for which the structure is conformally flat, as well as Segre types for which the corresponding PDE is integrable. These results were published in [1]. We then introduce the notion of characteristic integrals, discuss characteristic integrals in 3D and show that, for certain classes of second-order linearly degenerate dispersionless integrable PDEs, the corresponding characteristic integrals are parameterised by points on the Veronese variety. These results were published in [2].

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5

Branco, Meireles Joao. "Singular Perturbations and Ergodic Problems for degenerate parabolic Bellman PDEs in R^m with Unbounded Data". Doctoral thesis, Università degli studi di Padova, 2015. http://hdl.handle.net/11577/3424194.

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In this thesis we treat the first singular perturbation problem of a stochastic model with unbounded and controlled fast variables with success. Our methods are based on the theory of viscosity solutions, homogenisation of fully nonlinear PDEs and a careful analysis of the associated ergodic stochastic control problem in the whole space R^m. The text is divided in two parts. In the first chapter, we investigate the existence and uniqueness as well as a suitable stability of the solution to the associated ergodic problem that are crucial to characterize the effective Hamiltonian of the limit (effective) Cauchy problem in Chapter II of this thesis. The main achievement obtained in this part is a purely analytical proof for the uniqueness of solution to such ergodic problem. Since the state space of the problem is not compact, in general there are infinitely many solutions to the ergodic problem. However, if one restrict the class of solutions to the set of bounded-below functions, then it is known that uniqueness holds up to an additive constant. The existing proof relies on some probabilistic techniques employing the invariant probability measure for the associated stochastic process. Here we give a new proof, purely analytic, based on the strong maximum principle. We believe that our results can be interesting and useful for researchers in the PDE community. In the second chapter, we introduce our singular perturbation model of a stochastic control problem and we prove our main result: the convergence of the value function $V^\epsilon$ associated to the problem to the solution of the limiting equation. More precisely, we prove that the functions \underline{V} (t,x):=\liminf_{(\epsilon,t',x') \to (0,t,x)} \inf_{y \in \mathbb{R}^m} V^\epsilon (t',x',y) and \bar{V} (t,x) :=(\sup_{R} \bar{V}_R)^* (t,x) \text{ (upper semi-continuous envelope of $\sup_{R} \bar{V}_R$ )} where $\bar{V}_{R} (t,x):=\limsup_{(\epsilon, t',x') \to (0,t,x)} \sup_{y \in B_R (0)} V^\epsilon (t',x',y)$, are, respectively, a super and a subsolution of the effective Cauchy problem. As a corollary of this result, $V^\epsilon$ converges to the unique solution $V$ of the effective equation provided the equation admits the comparison principle for discontinuous viscosity solutions. The justification of this convergence is not trivial at all. It especially involves some regularity issues and a careful treatment of viscosity techniques and stochastic analysis. This result has never been obtained before.
In questa tesi viene trattato con successo il primo problema di perturbazione singolare di un modello stocastico con variabili veloci controllate e non limitate. I metodi si basano sulla teoria delle soluzioni di viscosità, omogeinizzazione dei PDE completamente non lineari, e su un'attenta analisi del problema stocastico ergodico associato, valido nell'intero spazio R^m. Il testo è diviso in due parti. Nel primo capitolo, saranno studiate l'esistenza, l'unicità e alcune proprietà di stabilità della soluzione del problema ergodico, riferito sopra, che sono essenziali per caratterizzare il Hamiltoniano effettivo che appare in un Problema di Cauchy "limite", che sarà descritto nel capitolo II di questa tesi. Il principale contributo, presentato in questa parte, è una prova puramente analitica dell'unicità della soluzione di questo problema ergodico. Siccome lo stato dello spazio del problema non è compatto, in generale ci sono un numero infinito di soluzioni a questo problema. Tuttavia, se uno limitasse la classe di soluzioni all'insieme di funzioni limitate inferiormente, allora è noto che l'unicità sarà mantenuta a meno di una costante. La prova esistente si basa su alcune tecniche probabilistiche che impiegano la misura di probabilità invariante per l'associato processo stocastico. Qua verrà data una nuova prova, puramente analitica, basata sul principio del massimo. Si ritiene che il risultato potrà essere interessante ed utile per i ricercatori che lavorano all'interno della comunità di ricerca delle Equazioni Differenziali alle derivate Parziali (PDE). Nel secondo capitolo, sarà introdotto un modello di perturbazione singolare di un problema di controllo stocastico, e provato il risultato principale: la convergenza della funzione valore $V^\epsilon$, associata al nostro problema, per soluzione dell'equazione limite. Più precisamente, sarà provato che le funzioni: \underline{V} (t,x):=\liminf_{(\epsilon,t',x') \to (0,t,x)} \inf_{y \in \mathbb{R}^m} V^\epsilon (t',x',y) e \bar{V} (t,x) :=(\sup_{R} \bar{V}_R)^* (t,x) \text{ (upper semi-continuous envelope of $\sup_{R} \bar{V}_R$ )} dove $\bar{V}_{R} (t,x):=\limsup_{(\epsilon, t',x') \to (0,t,x)} \sup_{y \in B_R (0)} V^\epsilon (t',x',y)$, sono, rispettivamente, una super soluzione e una sottosoluzione del problema effettivo di Cauchy. Come corollario di questo risultato, $V^\epsilon$ converge all'unica soluzione V della equazione effettiva se l'equazione limite permette il principio di comparazione per le soluzioni di viscosità discontinue. La motivazione di questa convergenza non è ovvia del tutto. Coinvolge specialmente alcuni problemi di regolarità e un trattamento attento delle tecniche di viscosità e di analisi stocastica. Questo risultato è nuovo e non è mai stato ottenuto, prima d'ora, nella letteratura Matematica.

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6

Peillon, Etienne. "Simulation and analysis of sign-changing Maxwell’s equations in cold plasma". Electronic Thesis or Diss., Institut polytechnique de Paris, 2024. http://www.theses.fr/2024IPPAE004.

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De nos jours, les plasmas sont principalement utilisés à des fins industrielles. L'un des exemples les plus fréquemment cités d'utilisation industrielle est la production d'énergie électrique via des réacteurs nucléaires à fusion. Pour contenir le plasma correctement à l'intérieur du réacteur, un champ magnétique est imposé en arrière-plan, et la densité et la température du plasma doivent être précisément contrôlées. Cela est effectué en envoyant des ondes électromagnétiques à des fréquences et dans des directions spécifiques en fonction des caractéristiques du plasma.La première partie de cette thèse de doctorat est consacrée à l'étude du modèle du plasma avec un fort champ magnétique en arrière-plan, ce qui correspond à un métamatériau hyperbolique. L'objectif est d'étendre les résultats existant en 2D au cas 3D et de dériver une condition de radiation. Nous introduisons une séparation des champs électriques et magnétiques ressemblant à la décomposition TE et TM habituelle, puis nous présentons quelques résultats sur les deux problèmes résultants. Les résultats sont dans un état très partiel et constituent un brouillon approximatif sur le sujet.La deuxième partie étudie l'EDP dégénérée associée aux ondes résonantes « lower-hybrid » dans le plasma. Le problème aux limites associé est bien posé dans un cadre variationnel « naturel ». Cependant, ce cadre n'inclut pas le comportement singulier présenté par les solutions physiques obtenues via le principe d'absorption limite. Ce comportement singulier est important du point de vue physique car il induit le chauffage du plasma mentionné précédemment. Un des résultats clés de cette deuxième partie est la définition d'une notion de saut à travers l'interface à l'intérieur du domaine, ce qui permet de caractériser la décomposition de la solution d'absorption limite en parties régulière et singulière
Nowadays, plasmas are mainly used for industrial purpose. One of the most frequently cited examples of industrial use is electric energy production via fusion nuclear reactors. Then, in order to contain plasma properly inside the reactor, a background magnetic field is imposed, and the density and temperature of the plasma must be precisely controlled. This is done by sending electromagnetic waves at specific frequencies and directions depending on the characteristics of the plasma.The first part of this PhD thesis consists in the study of the model of plasma in a strong background magnetic field, which corresponds to a hyperbolic metamaterial. The objective is to extend the existing results in 2D to the 3D-case and to derive a radiation condition. We introduce a splitting of the electric and magnetic fields resembling the usual TE and TM decomposition, then, it gives some results on the two resulting problems. The results are in a very partial state, and constitute a rough draft on the subject.The second part consists in the study of the degenerate PDE associated to the lower-hybrid resonant waves in plasma. The associated boundary-value problem is well-posed within a ``natural'' variational framework. However, this framework does not include the singular behavior presented by the physical solutions obtained via the limiting absorption principle. Notice that this singular behavior is important from the physical point of view since it induces the plasma heating mentioned before. One of the key results of this second part is the definition of a notion of weak jump through the interface inside the domain, which allows to characterize the decomposition of the limiting absorption solution into a regular and a singular parts

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7

Ikeda, Katsumoto. "Magnetothermoelectric properties of the degenerate semiconductor Hg1-xFexSe". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ53000.pdf.

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8

Maizurna, Isna. "Semigroup methods for degenerate cauchy problems and stochastic evolution equations /". Title page, abstract and contents only, 1999. http://web4.library.adelaide.edu.au/theses/09PH/09phm2328.pdf.

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9

Zhan, Yi. "Viscosity solutions of nonlinear degenerate parabolic equations and several applications". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ49931.pdf.

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10

Hiller, Christine Louise. "'Daddy's girls', 'degenerate daughters', tracing interconnected violences within women's 'survivor' narratives". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0001/MQ40649.pdf.

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11

Khut, Chiew-Lee. "Primacy of ideology? : the confiscation and exchange of "degenerate art" in the Third Reich /". Title page, abstract and table of contents only, 2001. http://web4.library.adelaide.edu.au/theses/09ARM/09armk45.pdf.

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12

Giatsidis, Christos. "Graph Mining and Community Evaluation with Degeneracy". Palaiseau, Ecole polytechnique, 2013. http://pastel.archives-ouvertes.fr/docs/00/95/96/15/PDF/thesisA.pdf.

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L'étude et l'analyse des réseaux sociaux attirent l'attention d'une variété de sciences (psychologie, statistiques, sociologie). Parmi elles, le domaine de la fouille de données offre des outils pour extraire automatiquement des informations utiles sur les propriétés de ces réseaux. Plus précisément, la fouille de graphes répond au besoin de modéliser et d'étudier les réseaux sociaux en particulier dans le cas des grandes communautés que l'on trouve habituellement dans les médias en ligne oú la taille des réseaux sociaux est trop grande pour les méthodes manuelles. La modélisation générale d'un réseau social est basée sur des structures de graphes. Les sommets du graphe représentent les individus et les arêtes des actions différentes ou des types de liens sociaux entre les individus. Une communauté est définie comme un sous-graphe (d'un réseau social) et se caractérise par des liens denses. Plusieurs mesures ont été précédemment proposées pour l'évaluation des divers aspects de la qualité de ces communautés mais la plupart d'entre elles ignorent diverses propriétés des interactions entre individus (par exemple l'orientation de ces liens). Dans la recherche présentée ici, le concept de "k-core" est utilisé comme un moyen d'évaluer les communautés et d'en extraire des informations. La structure de "k-core" mesure la robustesse d'un réseau non orienté en utilisant la dégénérescence du graphe. En outre, des extensions du principe de dégénérescence sont introduites pour des réseaux dont les arêtes possèdent plus d'informations que celles non orientées. Le point de départ est l'exploration des attributs qui peuvent être extraits des graphes non orientés (réseaux sociaux). Sur ce point, la dégénérescence est utilisée pour évaluer les caractéristiques d'une collaboration entre individus et sur l'ensemble de la communauté - une propriété non capturée par les métriques sur les sommets individuels ou par les métriques d'évaluation communautaires traditionnelles. Ensuite, cette méthode est étendue aux graphes pondérés, orientés et signés afin d'offrir de nouvelles mesures d'évaluation pour les réseaux sociaux. Ces nouvelles fonctionnalités apportent des outils de mesure de la collaboration dans les réseaux sociaux oú l'on peut attribuer un poids ou un orientation à une interaction et fournir des moyens alternatifs pour capturer l'importance des individus au sein d'une communauté. Pour les graphes signés, l'extension de la dégénérescence permet de proposer des métriques supplémentaires qui peuvent être utilisées pour modéliser la confiance. De plus, nous introduisons une approche de partitionnement basée sur le traitement du graphe de manière hiérarchique, hiérarchie fournie par le principe de "core expansion sequence" qui partitionne le graphe en différents niveaux ordonnés conformément à la décomposition "k-core". Les modèles théoriques de graphes sont ensuite appliqués sur des graphes du monde réel pour examiner les tendances et les comportements. Les jeux de données explorés incluent des graphes de collaborations scientifiques et des graphes de citations (DBLP et ARXIV), une instance de graphe interne de Wikipédia et des réseaux basés sur la confiance entre les individus (par exemple Epinions et Slashdot). Les conclusions sur ces ensembles de données sont significatives et les modèles proposés offrent des résultats intuitifs
The study and analysis of social networks attract attention from a variety of Sciences (psychology, statistics, sociology). Among them, the field of Data Mining offers tools to automatically extract useful information on properties of those networks. More specifically, Graph Mining serves the need to model and investigate social networks especially in the case of large communities - usually found in online media - where social networks are prohibitively large for non-automated methodologies. The general modeling of a social network is based on graph structures. Nodes of the graph represent individuals and edges signify different actions or types of social connections between them. A community is defined as a subgraph (of a social network) and is characterized by dense connections. Various measures have been proposed to evaluate different quality aspects of such communities - in most cases ignoring various properties of the connections (e. G. Directionality). In the work presented here, the k-core concept is used as a means to evaluate communities and extract information. The k-core structure essentially measures the robustness of an undirected network through degeneracy. Further more extensions of degeneracy are introduced to networks that their edges offer more information than the undirected type. Starting point is the exploration of properties that can be extracted from undirected graphs (of social networks). On this, degeneracy is used to evaluate collaboration features - a property not captured by the single node metrics or by the established community evaluation metrics - of both individuals and the entire community. Next, this process is extended for weighted, directed and signed graphs offering a plethora of novel evaluation metrics for social networks. These new features offer measurement tools for collaboration in social networks where we can assign a weight or a direction to a connection and provide alternative ways to signify the importance of individuals within a community. For signed graphs the extension of degeneracy offers additional metrics that can be used for trust management. Moreover, a clustering approach is introduced which capitalizes on processing the graph in a hierarchical manner provided by its core expansion sequence, an ordered partition of the graph into different levels according to the k-core decomposition The graph theoretical models are then applied in real world graphs to investigate trends and behaviors. The datasets explored include scientific collaboration and citation graphs (DBLP and ARXIV), a snapshot of Wikipedia's inner graph and trust networks (e. G. Epinions and Slashdot). The findings on these datasets are interesting and the proposed models offer intuitive results

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13

Zheng, Tianyu. "Periodic SIW lines with degenerate band edge for the excitation of giant resonances". Thesis, Sorbonne université, 2020. https://accesdistant.sorbonne-universite.fr/login?url=http://theses-intra.upmc.fr/modules/resources/download/theses/2020SORUS087.pdf.

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Dans cette thèse, nous décrivons la conception de guides d'onde intégrés au substrat (substrate integrated substrates, SIW) qui supportent des dégénérescences du quatrième ordre en bord de bandes interdites du diagramme de Brillouin (degenerate band edge, DBE). Le DBE conduit à des « résonances géantes » et à résonateurs à fort facteur de qualité. Le choix de la technologie SIW peut permettre l'utilisation du concept DBE dans les circuits intégrés hyperfréquences et aux ondes millimétriques. Les applications de ce concept sont nombreuses : résonateurs à fort facteur de qualité, oscillateurs robustes aux charges externes, capteurs à directivité et sensibilité élevées. Ici nous caractérisons un type de cellules élémentaires qui permet de concevoir un point DBE après une analyse de plusieurs types de cellules. Sur la base de ces résultats, plusieurs conceptions de SIW qui supportent une DBE sont présentées. On considère l'influence des pertes, des perturbations géométriques et l’effet dû à la troncature de la ligne périodique. Les caractéristiques DBE typiques, telles que l'amplification du champ et une forte augmentation du facteur Q et du retard de groupe par rapport au nombre de cellules sont observées dans un résonateur tronqué, dans des situations sans perte et avec perte. Des transitions nécessaires pour alimenter les lignes SIWs sont conçues et permettent d’effectuer les mesures de prototypes qui valident pleinement les analyses théoriques. Enfin, la procédure de conception est également appliquée à un guide d'ondes intégré multicouche, particulièrement adapté aux applications à ondes millimétrique, montrant la versatilité de la méthodologie proposée
In this thesis, we describe the synthesis of periodic substrate-integrated waveguide (SIW) supporting degenerate band edge (DBE) points. The DBE point is a special fourth-order degenerate point encountered at the edge of the stopband in a periodic structure, which leads to field enhancement and high-Q resonances. The choice of SIW technology can lead to the use of the DBE concept in microwave and mm-wave integrated circuits, given the easy fabrication, low profile and low-cost features of this technology. Applications of this concept will be oscillators having low threshold currents and being robust to external loading, and sensors with high directivity and sensitivity. Conditions for the design of a unit cell providing a DBE point are given after an analysis of several kinds of unit cells. Based on these guidelines, several SIWs-DBE designs are presented. The influence of losses, of geometrical perturbations, and of truncation are considered. Typical DBE characteristics, such as field enhancement and a steep increase of Q factor and group delay vs. the number of cells in a truncated resonator are observed in lossless and lossy situations. Feeding transitions are designed to feed the SIWs-DBE lines and to perform measurements which fully validate the theoretical analyses. Finally, the design procedure is also applied to a multilayer integrated waveguide, particularly suitable for integrated millimeter-wave applications, showing the versatility of the proposed methodology

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14

Andersen, Shannon I. "A profile of long-term degenerative hip disease patients". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/MQ33336.pdf.

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15

AraÃjo, DamiÃo JÃnio GonÃalves. "EquaÃÃes diferenciais elÃpticas nÃo-variacionais, singulares/degeneradas : uma abordagem geomÃtrica". Universidade Federal do CearÃ, 2012. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=9152.

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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
Neste presente trabalho, faremos o estudo de importantes propriedades geomÃtricas e analÃticas de soluÃÃes de equaÃÃes diferenciais parciais elÃpticas totalmente nÃo-lineares do tipo: singulares e degeneradas. O estudo de processos de combustÃo que se degeneram ao longo do conjunto de anulamento da densidade de um gÃs, um caso particular de problemas do tipo "quenching", apresentam em sua modelagem equaÃÃes singulares que estÃo descritas neste trabalho. Nesta primeira parte iremos obter propriedades de uma soluÃÃo minimal, que vÃo desde o controle completo Ãtimo, atÃ a obtenÃÃo de estimativas de Hausdorff da fronteira livre singular. Por fim, iremos obter a regularidade Ãtima de soluÃÃes de equaÃÃes em que suas propriedades de difusÃo(elipticidade) se deterioram na ordem de uma potÃncia do seu gradiente ao longo do conjunto em que tal taxa de variaÃÃo se anula.
In this work we study important geometric and analytic properties to solutions of fully nonlinear elliptic partial differential equations, both singular and degenerate types. The study of combustion processes that degenerate along the null-set of the density of a gas, a particular case of quenching problems, present in their modeling, equations described in this work. In this first part we obtain properties of a minimal solution, since the complete optimal control until the Hausdorff estimates of the singular free boundary. Ultimately, we obtain the optimal regularity to equation solutions where their diffusion property (elipticity) deterorate in a power of their gradient along the set where such rate of variation nullifies.

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16

GOFFI, ALESSANDRO. "Topics in nonlinear PDEs: from Mean Field Games to problems modeled on Hörmander vector fields". Doctoral thesis, Gran Sasso Science Institute, 2019. http://hdl.handle.net/20.500.12571/9808.

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This thesis focuses on qualitative and quantitative aspects of some nonlinear PDEs arising in optimal control and differential games, ranging from regularity issues to maximum principles. More precisely, it is concerned with the analysis of some fully nonlinear second order degenerate PDEs over Hörmander vector fields that can be written in Hamilton-Jacobi-Bellman and Isaacs form and those arising in the recent theory of Mean Field Games, where the prototype model is described by a coupled system of PDEs involving a backward Hamilton-Jacobi and a forward Fokker-Planck equation. The thesis is divided in three parts. The first part is devoted to analyze strong maximum principles for fully nonlinear second order degenerate PDEs structured on Hörmander vector fields, having as a particular example fully nonlinear subelliptic PDEs on Carnot groups. These results are achieved by introducing a notion of subunit vector field for these nonlinear degenerate operators in the spirit of the seminal works on linear equations. As a byproduct, we then prove some new strong comparison principles for equations that can be written in Hamilton-Jacobi-Bellman form and Liouville theorems for some second order fully nonlinear degenerate PDEs. The second part of the thesis deals with time-dependent fractional Mean Field Game systems. These equations arise when the dynamics of the average player is described by a stable Lévy process to which corresponds a fractional Laplacian as diffusion operator. More precisely, we establish existence and uniqueness of solutions to such systems of PDEs with regularizing coupling among the equations for every order of the fractional Laplacian $sin(0,1)$. The existence of solutions is addressed via the vanishing viscosity method and we prove that in the subcritical regime the equations are satisfied in classical sense, while if $sleq1/2$ we find weak energy solutions. To this aim, we develop an appropriate functional setting based on parabolic Bessel potential spaces. We finally show uniqueness of solutions both under the Lasry-Lions monotonicity condition and for short time horizons. The last part focuses on the regularizing effect of evolutive Hamilton-Jacobi equations with Hamiltonian having superlinear growth in the gradient and unbounded right-hand side. In particular, the analysis is performed both for viscous Hamilton-Jacobi equations and its fractional counterpart in the subcritical regime via a duality method. The results are accomplished exploiting the regularity of solutions to Fokker-Planck-type PDEs with rough velocity fields in parabolic Sobolev and Bessel potential spaces respectively.

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17

Şanlı, Zafer Çöken Abdilkadir Ceylan. "Dejenere helisler üzerine /". Isparta : SDÜ Fen Bilimleri Enstitüsü, 2009. http://tez.sdu.edu.tr/Tezler/TF01302.pdf.

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18

McDonald, Kirsten Margaret Elizabeth. "Degenerative joint disease, what can it tell us about the early historic Maya at Lamanai?" Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ57994.pdf.

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19

Thie, Norman Michael Reinhold. "Evaluation of glucosamine sulphate and ibuprofen for patients with temporomandibular degenerative joint disease with pain". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0008/MQ59887.pdf.

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20

Axelsson, Mats. "Bone spavin : clinical and epidemiological aspects of degenerative joint disease in the distal tarsus in Icelandic horses /". Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2000. http://epsilon.slu.se/avh/2000/91-576-5918-4.pdf.

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21

Boone, Celia K. "Integrated pest management of Thrips tabaci Lindeman (Thysanoptera: thripidae) in greenhouse cucumber production (Amblyseius cucumeris, Iphiseius degenerans, Cucumis sativus)". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ49319.pdf.

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22

Pan, Ligang. "Third-order nonlinear optical study on sublimated/Langmuir-Blodgett thin films of lanthanide porphyrin phthalocyanine dimer/heterodimer and symmetric trimer systems by time-resolved non-degenerate four-wave mixing". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq21858.pdf.

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23

Eksell, Per. "Imaging of bone spavin : a radiographic and scintigraphic study of degenerative joint disease in the distal tarsus in Icelandic horses /". Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2000. http://epsilon.slu.se/avh/2000/91-576-5922-2.pdf.

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24

Stepczynski, Jadwiga Maja. "Defining the molecular phenotype of the rat retina during the commitment phase of light-induced retinal degeneration, a model of human retinal degenerative disease". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ60502.pdf.

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25

Chaudru, de Raynal Paul Éric. "Équations différentielles stochastiques : résolubilité forte d'équations singulières dégénérées ; analyse numérique de systèmes progressifs-rétrogrades de McKean-Vlasov". Phd thesis, Université Nice Sophia Antipolis, 2013. http://tel.archives-ouvertes.fr/tel-00954417.

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Cette thèse traite de deux sujets: la résolubilité forte d'équations différentielles stochastiques à dérive hölderienne et bruit hypoelliptique et la simulation de processus progressifs-rétrogrades découplés de McKean-Vlasov. Dans le premier cas, on montre qu'un système hypoelliptique, composé d'une composante diffusive et d'une composante totalement dégénérée, est fortement résoluble lorsque l'exposant de la régularité Hölder de la dérive par rapport à la composante dégénérée est strictement supérieur à 2/3. Ce travail étend au cadre dégénéré les travaux antérieurs de Zvonkin (1974), Veretennikov (1980) et Krylov et Röckner (2005). L'apparition d'un seuil critique pour l'exposant peut-être vue comme le prix à payer pour la dégénérescence. La preuve repose sur des résultats de régularité de la solution de l'EDP associée, qui est dégénérée, et est basée sur une méthode parametrix. Dans le second cas, on propose un algorithme basé sur les méthodes de cubature pour la simulation de processus progessifs-rétrogrades découplés de McKean-Vlasov apparaissant dans des problèmes de contrôle dans un environnement de type champ moyen. Cet algorithme se divise en deux parties. Une première étape de construction d'un arbre de particules, à dynamique déterministe, approchant la loi de la composante progressive. Cet arbre peut être paramétré de manière à obtenir n'importe quel ordre d'approximation (en terme de pas de discrétisation de l'intervalle). Une seconde étape, conditionnelle à l'arbre, permettant l'approximation de la composante rétrograde. Deux schémas explicites sont proposés permettant un ordre d'approximation de 1 et 2.

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26

Nguyen, Phuoc Tai. "Trace au bord de solutions d'équations de Hamilton-Jacobi elliptiques et trace initiale de solutions d'équations de la chaleur avec absorption sur-linéaire". Phd thesis, Université François Rabelais - Tours, 2012. http://tel.archives-ouvertes.fr/tel-00710410.

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Cette thèse est constituée de trois parties. Dans la première partie, on s'intéresse au problème de trace au bord d'une solution positive de l'équation de Hamilton-Jacobi (E1) $-\Delta u+g(|\nabla u|)=0$ dans un domaine borné $\Omega$ de ${\mathbb R}^N$, satisfaisant (E2) $u = \mu$ sur $\partial \Omega$. Si $g(r) \geq r^q$ avec $q > 1$, on prouve que toute solution positive de (E1) admet une trace au bord considérée comme une mesure de Borel régulière, pas nécessairement localement bornée. Si $g(r) = r^q$ avec $1 < q < q_c = \frac{N+1}{N}$ , on montre l'existence d'une solution positive dont la trace au bord est une mesure de Borel régulière $\nu \not \equiv \infty$ et on caractérise les singularités frontières isolées de solutions positives. Si $g(r) = r^q$ avec $q_c \leq q < 2$, on établit une condition nécessaire de résolution en terme de capacité de Bessel $C_{\frac{2-q}{q},q'} . On étudie aussi des ensembles éliminables au bord pour des solutions modérées. La deuxième partie est consacrée à étudier la limite, lorsque $k \to \infty$, de solutions d'équation $\partial_t u - \Delta u + f(u) =0$ dans ${\mathbb R}^N \times (0;\infty)$ avec donnée initiale $k\delta_0$ où $0$ est la masse de Dirac concentrée à l'origine et f est une fonction positive, continue, croissante et satisfaisant $f(0) = f^{-1}(0) = 0$. On prouve, sous certaines hypothèses portant sur f, qu'il existe essentiellement trois types de comportement possible en fonction des valeurs finies ou infinies des intégrales $\int_1^\infty f^{-1}(s)ds$ et $\int_1^\infty F^{-1/2}(s)ds$, où $F(s)=\int_0^s f(r)dr$. Grâce à ces résultats, on donne une nouvelle construction de la trace initiale et quelques résultats d'unicité et de non-unicité de solutions dont la donnée initiale n'est pas bornée. Dans la troisième partie, on élargit le cadre de nos investigations et généralise les résultats obtenus dans la deuxième partie au cas où l'opérateur est non-linéaire. En particulier, on s'intéresse à des propriétés qualitatives de solutions positives de l'équation $ \partial_t u-\Delta_p u+f(u)=0$ où $p > 1, \Delta_p u = div(\abs{\nabla u}^{p-2}\nabla u)$ et $f$ est une fonction continue, croissante, positive et satisfaisant $f(0) = 0 = f^{-1}(0)$. Si $p > \frac{2N}{N+1}$, on fournit une condition suffisante portant sur f pour l'existence et l'unicité des solutions fondamentales de données initiales $k\delta_0$ et on étudie la limite, lorsque $k \to \infty$, qui dépend du fait que $f^{-1}$ et $F^{-1/p}$ soient intégrables à l'infini ou pas, où $F(s) =\int_0^s f(r)dr. On donne aussi de nouveaux résultats de non-unicité de solutions avec donnée initiale non bornée. Si $p \geq 2$, on prouve que toute solution positive admet une trace initiale dans la classe de mesures de Borel régulières positives. Finalement on applique les résultats ci-dessus au cas modèle $f(u)=u^\alpha \ln^\beta(u+1)$ avec $\alpha>0$ et $\beta>0$.

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27

Hatchi, Roméo. "Analyse mathématique de modèles de trafic routier congestionné". Thesis, Paris 9, 2015. http://www.theses.fr/2015PA090048/document.

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Cette thèse est dédiée à l'étude mathématique de quelques modèles de trafic routier congestionné. La notion essentielle est l'équilibre de Wardrop. Elle poursuit des travaux de Carlier et Santambrogio avec des coauteurs. Baillon et Carlier ont étudié le cas de grilles cartésiennes dans $\RR^2$ de plus en plus denses, dans le cadre de la théorie de $\Gamma$-convergence. Trouver l'équilibre de Wardrop revient à résoudre des problèmes de minimisation convexe. Dans le chapitre 2, nous regardons ce qui se passe dans le cas de réseaux généraux, de plus en plus denses, dans $\RR^d$. Des difficultés nouvelles surgissent par rapport au cas initial de réseaux cartésiens et pour les contourner, nous introduisons la notion de courbes généralisées. Des hypothèses structurelles sur ces suites de réseaux discrets sont nécessaires pour s'assurer de la convergence. Cela fait alors apparaître des fonctions qui sont des sortes de distances de Finsler et qui rendent compte de l'anisotropie du réseau. Nous obtenons ainsi des résultats similaires à ceux du cas cartésien. Dans le chapitre 3, nous étudions le modèle continu et en particulier, les problèmes limites. Nous trouvons alors des conditions d'optimalité à travers une formulation duale qui peut être interprétée en termes d'équilibres continus de Wardrop. Cependant, nous travaillons avec des courbes généralisées et nous ne pouvons pas appliquer directement le théorème de Prokhorov, comme cela a été le cas dans \cite{baillon2012discrete, carlier2008optimal}. Pour pouvoir néanmoins l'utiliser, nous considérons une version relaxée du problème limite, avec des mesures d'Young. Dans le chapitre 4, nous nous concentrons sur le cas de long terme, c'est-à-dire, nous fixons uniquement les distributions d'offre et de demande. Comme montré dans \cite{brasco2013congested}, le problème de l'équilibre de Wardrop est équivalent à un problème à la Beckmann et il se réduit à résoudre une EDP elliptique, anisotropique et dégénérée. Nous utilisons la méthode de résolution numérique de Lagrangien augmenté présentée dans \cite{benamou2013augmented} pour proposer des exemples de simulation. Enfin, le chapitre 5 a pour objet l'étude de problèmes de Monge avec comme coût une distance de Finsler. Cela se reformule en des problèmes de flux minimal et une discrétisation de ces problèmes mène à un problème de point-selle. Nous le résolvons alors numériquement, encore grâce à un algorithme de Lagrangien augmenté
This thesis is devoted to the mathematical analysis of some models of congested road traffic. The essential notion is the Wardrop equilibrium. It continues Carlier and Santambrogio's works with coauthors. With Baillon they studied the case of two-dimensional cartesian networks that become very dense in the framework of $\Gamma$-convergence theory. Finding Wardrop equilibria is equivalent to solve convex minimisation problems.In Chapter 2 we look at what happens in the case of general networks, increasingly dense. New difficulties appear with respect to the original case of cartesian networks. To deal with these difficulties we introduce the concept of generalized curves. Structural assumptions on these sequences of discrete networks are necessary to obtain convergence. Sorts of Finsler distance are used and keep track of anisotropy of the network. We then have similar results to those in the cartesian case.In Chapter 3 we study the continuous model and in particular the limit problems. Then we find optimality conditions through a duale formulation that can be interpreted in terms of continuous Wardrop equilibria. However we work with generalized curves and we cannot directly apply Prokhorov's theorem, as in \cite{baillon2012discrete, carlier2008optimal}. To use it we consider a relaxed version of the limit problem with Young's measures. In Chapter 4 we focus on the long-term case, that is, we fix only the distributions of supply and demand. As shown in \cite{brasco2013congested} the problem of Wardrop equilibria can be reformulated in a problem à la Beckmann and reduced to solve an elliptic anisotropic and degenerated PDE. We use the augmented Lagrangian scheme presented in \cite{benamou2013augmented} to show a few numerical simulation examples. Finally Chapter 5 is devoted to studying Monge problems with as cost a Finsler distance. It leads to minimal flow problems. Discretization of these problems is equivalent to a saddle-point problem. We then solve it numerically again by an augmented Lagrangian algorithm

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28

Karimou, Gazibo Mohamed. "Etudes mathématiques et numériques des problèmes paraboliques avec des conditions aux limites". Phd thesis, Université de Franche-Comté, 2013. http://tel.archives-ouvertes.fr/tel-00950759.

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Cette thèse est centrée autour de l'étude théorique et de l'analyse numérique des équations paraboliques non linéaires avec divers conditions aux limites. La première partie est consacrée aux équations paraboliques dégénérées mêlant des phénomènes non-linéaires de diffusion et de transport. Nous définissons des notions de solutions entropiques adaptées pour chacune des conditions aux limites (flux nul, Robin, Dirichlet). La difficulté principale dans l'étude de ces problèmes est due au manque de régularité du flux pariétal pour traiter les termes de bords. Ceci pose un problème pour la preuve d'unicité. Pour y remédier, nous tirons profit du fait que ces résultats de régularités sur le bord sont plus faciles à obtenir pour le problème stationnaire et particulièrement en dimension un d'espace. Ainsi par la méthode de comparaison "fort-faible" nous arrivons à déduire l'unicité avec le choix d'une fonction test non symétrique et en utilisant la théorie des semi-groupes non linéaires. L'existence de solution se démontre en deux étapes, combinant la méthode de régularisation parabolique et les approximations de Galerkin. Nous développons ensuite une approche directe en construisant des solutions approchées par un schéma de volumes finis implicite en temps. Dans les deux cas, on combine les estimations dans les espaces fonctionnels bien choisis avec des arguments de compacité faible ou forte et diverses astuces permettant de passer à la limite dans des termes non linéaires. Notamment, nous introduisons une nouvelle notion de solution appelée solution processus intégrale dont l'objectif, dans le cadre de notre étude, est de pallier à la difficulté de prouver la convergence vers une solution entropique d'un schéma volumes finis pour le problème de flux nul au bord. La deuxième partie de cette thèse traite d'un problème à frontière libre décrivant la propagation d'un front de combustion et l'évolution de la température dans un milieu hétérogène. Il s'agit d'un système d'équations couplées constitué de l'équation de la chaleur bidimensionnelle et d'une équation de type Hamilton-Jacobi. L'objectif de cette partie est de construire un schéma numérique pour ce problème en combinant des discrétisations du type éléments finis avec les différences finies. Ceci nous permet notamment de vérifier la convergence de la solution numérique vers une solution onde pour un temps long. Dans un premier temps, nous nous intéressons à l'étude d'un problème unidimensionnel. Très vite, nous nous heurtons à un problème de stabilité du schéma. Cela est dû au problème de prise en compte de la condition de Neumann au bord. Par une technique de changement d'inconnue et d'approximation nous remédions à ce problème. Ensuite, nous adaptons cette technique pour la résolution du problème bidimensionnel. A l'aide d'un changement de variables, nous obtenons un domaine fixe facile pour la discrétisation. La monotonie du schéma obtenu est prouvée sous une hypothèse supplémentaire de propagation monotone qui exige que la frontière libre se déplace dans les directions d'un cône prescrit à l'avance.

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29

Mombourquette, Ethan. "On Holder continuity of weak solutions to degenerate linear elliptic partial differential equations". 2013. http://hdl.handle.net/10222/35442.

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For degenerate elliptic partial differential equations, it is often desirable to show that a weak solution is smooth. The first and most difficult step in this process is establishing local Hölder continuity. Sufficient conditions for establishing continuity have already been documented in [FP], [SW1], and [MRW], and their necessity in [R]. However, the complexity of the equations discussed in those works makes it difficult to understand the core structure of the arguments employed. Here, we present a harmonic-analytic method for establishing Hölder continuity of weak solutions in context of a simple linear equation div(Q?u) = f in a homogeneous space structure in order to showcase the form of the argument. Ad- ditionally, we correct an oversight in the adaptation of the John-Nirenberg inequality presented in [SW1], restricting it to a much smaller class of balls.

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30

Tyranowski, Tomasz Michal. "Geometric Integration Applied to Moving Mesh Methods and Degenerate Lagrangians". Thesis, 2014. https://thesis.library.caltech.edu/8038/1/Tyranowski_Tomasz_2014.pdf.

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Moving mesh methods (also called r-adaptive methods) are space-adaptive strategies used for the numerical simulation of time-dependent partial differential equations. These methods keep the total number of mesh points fixed during the simulation, but redistribute them over time to follow the areas where a higher mesh point density is required. There are a very limited number of moving mesh methods designed for solving field-theoretic partial differential equations, and the numerical analysis of the resulting schemes is challenging. In this thesis we present two ways to construct r-adaptive variational and multisymplectic integrators for (1+1)-dimensional Lagrangian field theories. The first method uses a variational discretization of the physical equations and the mesh equations are then coupled in a way typical of the existing r-adaptive schemes. The second method treats the mesh points as pseudo-particles and incorporates their dynamics directly into the variational principle. A user-specified adaptation strategy is then enforced through Lagrange multipliers as a constraint on the dynamics of both the physical field and the mesh points. We discuss the advantages and limitations of our methods. The proposed methods are readily applicable to (weakly) non-degenerate field theories---numerical results for the Sine-Gordon equation are presented.

In an attempt to extend our approach to degenerate field theories, in the last part of this thesis we construct higher-order variational integrators for a class of degenerate systems described by Lagrangians that are linear in velocities. We analyze the geometry underlying such systems and develop the appropriate theory for variational integration. Our main observation is that the evolution takes place on the primary constraint and the 'Hamiltonian' equations of motion can be formulated as an index 1 differential-algebraic system. We then proceed to construct variational Runge-Kutta methods and analyze their properties. The general properties of Runge-Kutta methods depend on the 'velocity' part of the Lagrangian. If the 'velocity' part is also linear in the position coordinate, then we show that non-partitioned variational Runge-Kutta methods are equivalent to integration of the corresponding first-order Euler-Lagrange equations, which have the form of a Poisson system with a constant structure matrix, and the classical properties of the Runge-Kutta method are retained. If the 'velocity' part is nonlinear in the position coordinate, we observe a reduction of the order of convergence, which is typical of numerical integration of DAEs. We also apply our methods to several models and present the results of our numerical experiments.

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31

Crouch, David Dale. "A Theoretical Study of the Generation of Squeezed-State Light via Degenerate Parametric Amplification". Thesis, 1988. https://thesis.library.caltech.edu/4376/3/Crouch_dd_1988.pdf.

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This thesis is primarily a theoretical study of degenerate parametric amplification as a means of generating squeezed-state light.

i) A wideband traveling-wave formalism is developed for analyzing quantum mechanically a degenerate parametric amplifier. The formalism is based on spatial differential equations — spatial Langevin equations — that propagate temporal Fourier components of the field through the nonlinear medium. In addition to the parametric nonlinearity, the Langevin equations include absorption and associated fluctuations, dispersion, and pump quantum fluctuations. The dominant effects of dispersion and pump quantum fluctuations on the squeezing produced by a degenerate parametric amplifier are analyzed.

ii) The wideband formalism of i) is used to carry out a more detailed analysis of the effects of phase mismatching. With the assumption of a lossless medium and a classical pump, we find that parametric amplification is capable of generating squeezed-state light over a wide band if materials with large χ⁽²⁾ nonlinearities can be found, and that the squeezing bandwidth can be enhanced by phase mismatching away from degeneracy.

iii) We consider again the effect of pump quantum fluctuations on the squeezing produced by parametric amplification. We perform discrete-mode calculations for a parametric amplifier with a quantum pump, and discuss some of the limitations of calculations of this sort in quantum optics. We derive stochastic differential equations (SDEs) for one- and two-mode parametric amplifiers, and from them obtain an iterative solution showing that pump quantum fluctuations impose a limitation on the degree of squeezing obtainable from a parametric amplifier.

iv) A possible application of squeezing is considered; in particular, we study the effects of squeezing the intracavity noise in a laser oscillator. We solve the classical noise problem of a realistic laser model by making a bold — and possibly unrealizable — assumption, that the in-phase and quadrature Langevin sources which are responsible for the "noisiness" of the laser can be squeezed. We show that the effect of squeezing the in-phase quadrature is to reduce the phase noise, including the linewidth, of the laser but, due to amplitude-phase coupling, not to eliminate them altogether.

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32

Khut, Chiew-Lee 1971. "Primacy of ideology? : the confiscation and exchange of "degenerate art" in the Third Reich". 2001. http://web4.library.adelaide.edu.au/theses/09ARM/09armk45.pdf.

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Bibliography: leaves 156-167. The aim of this thesis is to show how in practice the National Socialists sacrificed ideological considerations to the material advantages that could be gained from the sale of "degenerate art". In practice the term "degenerate" was extended beyond modern art to include French Impressionist and Post-Impressionist art, specifically because they were highly saleable. This is evinced by the sales of "degenerate art" which were conducted by the Reichministerium für Volksklärung und Propaganda (RMVP). The record of the sales compiled by the propaganda ministry in the summer of 1941, provide conclusive evidence that the Reich government compromised its ideological position for financial gain. The sale of "degenerate art" conducted by order of the Reich at the Galerie Fischer auction in Lucerne in 1939, provides further evidence that the practice of confiscation was economically driven.

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33

Stawinoga, Agnieszka. "ASSESSMENT OF STOCHASTIC APPROXIMATION METHODS AND OF DEGENERACY DIAGNOSTIC TOOLS IN EXPONENTIAL RANDOM GRAPH MODELS". Tesi di dottorato, 2010. http://www.fedoa.unina.it/8357/1/stawinoga_agnieszka_23.pdf.

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In recent decades there has been an enormous growth of interest in the notion of social network and the methods of Social Network Analysis (SNA). The methodology developed in the field of network analysis has been categorized into descriptive methods and statistical methods. The statistical methods may be organized into two parts; the first group consists of dyadic and triadic methods which represent statistical models for subgraphs and the second group of statistical models for entire graphs and digraphs. In this work we pay attention to the Exponential Random Graph Models (ERGMs), the statistical models which provide a general framework for modeling dependent data where the dependence can be thought of as a neighborhood effect. The present manuscript is based on two main motivations. Firstly, we are interested to examine model diagnostics and check for degeneracy of ERGMs using different methods and functions. Secondly, we aim to evaluate and compare results obtained for networks of various sizes from three different estimation procedures such as Newton-Raphson, Robbins-Monro and Stepping.

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34

Sigurdsson, Steinn. "Dynamics of neutron stars and binaries in globular clusters or, Ménages à trois: revitalizing burnt out degenerates through partner swapping". Thesis, 1992. https://thesis.library.caltech.edu/6638/1/Sigurdsson_s_1992.pdf.

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Interaction cross-sections and collision cross-sections for a set of hard multi-mass binary-single star interactions are calculated in order to estimate three-body collision cross-sections in galactic globular clusters. The cross-sections are calculated by direct integration of binary-single star encounters, using Monte Carlo sampling to average over the three-body phase space. A number of mass-ratios physically relevant to the globular cluster environment are used. Differential energy transfer rates due to three-body interactions are calculated. Parametric approximations for the various cross-sections calculated are found. The results of the cross-sections are used to evaluate various formation scenarios for the pulsars PSR2127+11C (M15C) and PSR1744-24A (TER5A). In addition the contribution of the globular cluster system to the galactic birthrate of PSR1913+16 type systems is estimated. The dynamics and interactions of a test binary population in a number of globular cluster models are calculated in a static background. The cluster method used are isotropic multi-mass King models of varying concentration and density. The model developed is generalisable to an arbitrary cluster distribution function, including one evolving in time. Relative probabilities of different encounters are found for binaries on arbitrary trajectories in the various cluster models. The actual interaction rates of the test population are calculated by direct integration, using Monte Carlo sampling to average over the initial binary parameters. The number of neutron stars expected to be recycled in different concentration clusters is estimated with a particular view to understanding the pulsar population observed in clusters 47Tuc and M15. Estimates are also made of the binary density profile of the different concentration class clusters, and the final distribution in binary parameters. The production rate of "blue stragglers" and the interaction rate of (sub)giants and white dwarfs in the various clusters are also estimated.

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Dhara, Raj Narayan. "Existence and regularity theory in weighted Sobolev spaces and applications". Doctoral thesis, 2016. https://depotuw.ceon.pl/handle/item/2051.

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In the thesis we discuss several questions related to the study of degenerate, possibly nonlinear PDEs of elliptic type. At first we discuss the equivalent conditions between the validity of weighted Poincar\'e inequalities, structure of the functionals on weighted Sobolev spaces, isoperimetric inequalities and the existence and uniqueness of solutions to the degenerate nonlinear elliptic PDEs with nonhomogeneous boundary condition, having the form:\begin{eqnarray}\label{eqn:abs}\left\{\begin{array}{lll}{\rm div} \left( \rho (x)|\nabla u|^{p-2}\nabla u\right) =x^*,\\~~~~~~~~~~~~u-w \in W^{1,p}_{\rho,0} (\Omega),\end{array}\right.\end{eqnarray}involving any given $x^*\in (W^{1,p}_{\rho,0} (\Omega))^*$ and $w\in W^{1,p}_{\rho} (\Omega)$, where $u\in W^{1,p}_{\rho} (\Omega)$ and $W^{1,p}_{\rho} (\Omega)$ denotes certain weighted Sobolev space, $W^{1,p}_{\rho,0} (\Omega)$ is the completion of $\mathcal{C}_{0}^{\infty}(\Omega)$. As a next step, we undertake a natural question how to interpret the nonhomogenous boundary conditions in weighted Sobolev spaces, when the natural analytical tools, like trace embedding theorems, are missing. Our further goal is to contribute to solvability and uniqueness for degenerate elliptic PDEs with nonhomogenous boundary condition being the extension of~\eqref{eqn:abs}. In addition to the monotonicity method used in the first step of our discussion for the problem~\eqref{eqn:abs}, we also exploit Lax-Miligram theorem to treat the linear problem like:\begin{equation*}\begin{cases}-{\rm div} (A(x)\nabla u(x)) + B(x)\cdot\nabla u(x) + C(x)u(x) = x^{*}\ \ \text{for a.e.}\ x\in \Omega, \\~~~~~~~~~~~~~~~~~~ u(x) = g(x) \ \ \text{for a.e. }\ x\in \partial\Omega ,\end{cases}\end{equation*}as well as Ekeland's Variational Principle and Boccardo-Murat techniques to consider problem like:\begin{align*} \begin{cases} - {\rm div} \left( \rho (x)|\nabla u|^{p-2}\nabla u\right) - \lambda\, b(x)| u|^{p-2} u = x^*,\\~~~~~~~~~~~~~~~~~~~u-z \in X , \end{cases}\end{align*}where $p>1,\ \lambda>0$, and the operator $\mathcal{L}_{\lambda} u:= - {\rm div} \left( \rho (x)|\nabla u|^{p-2}\nabla u\right) - \lambda\, b(x)| u|^{p-2} u $ is non-monotone.For the study of the nonhomogeneous BVPs, we apply recent results due to Ka\l{}amajska and myself, where we constructed trace extension operator from weighted Orlicz-Slobodetskii spaces defined on the boundary of the domain to weighted Orlicz-Sobolev spaces in the domain. Information on the spectrum of the corresponding differential operator is also derived. Moreover, some nonexistence and nonuniqueness results are also analyzed.

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Tesi sul tema "Degenerate PDE"

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