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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
191

Certains études sur la minimalité et la propriété chaotique de dynamiques p-adicques et la régularité locale des series de Davenport avec translation de phase

Zhou, Dan 26 May 2009 (has links)
Dans cette thèse, nous étudions la minimalité et la propriété chaotique de systèmes dynamiques p-adiques. Nous étudions aussi des propriétés multifractales des séries de Davenport avec translation de phases. Dans la première partie, nous commençons par l'étude des systèmes dynamiques affines sur Zp. Nous trouvons une condition nécessaire et suffisante pour qu'un tel système soit minimal. En outre, nous exhibons toutes ses composantes strictement ergodiques si le système n'est pas minimal. De plus, nous étudions aussi les systèmes monômes sur le groupe 1+pZp. Ensuite nous étudions les polynômes localement dilatants et transitifs. Pour un tel polynôme, limité sur son ensemble de Julia, nous prouvons qu'il est conjugué à un sous-shift de type fini. Dans la deuxième partie, nous étudions les séries de Davenport avec translation de phases. Après avoir calculé le saut d'une telle série à chaque point, nous trouvons l'ensemble des points discontinus et obtenons une condition nécessaire et suffisante pour qu'une série de Davenport avec translation de phases soit continue sur R. La convergence ponctuelle de la série est aussi étudiée. Ensuite, nous estimons la borne inférieure de l'exposant hölderien de la série de Davenport avec de phase rationnelle et la borne supérieure du spectre de la singularité / In this thesis, we study the minimality and the chaotic property of p-adic dynamical systems and some multifractal properties of phase translated Davenport series. In the first part, we begin with the study of affine dynamical systems on Zp. We find a necessary and sufficient condition for such a system to be minimal. Furthermore, all its strictly ergodic components are exhibited when it is not minimal. In addition, we study monomial systems on the group 1 + pZp. Then transitive locally expanding polynomial systems are studied. It is proved that such a polynomial system, restricted to its Julia set, is conjugate to a subshift of finite type. In the second part, we study phase translated Davenport series. After having calculated the jump of the series at each point, we characterize the set of discontinuous points and get a sufficient and necessary condition for the series to be continuous on R. Furthermore, the pointwise convergence of the series is studied. Then we estimate the lower bound of the Hölder-exponent of rational translated Davenport series and get an upper bound estimation on the spectrum of singularity. The lower bound of the Hölder-exponent are also discussed for some irrational translated series
192

On Ergodic Theorems for Cesàro Convergence of Spherical Averages for Fuchsian Groups: Geometric Coding via Fundamental Domains

Drygajlo, Lars 04 November 2021 (has links)
The thesis is organized as follows: First we state basic ergodic theorems in Section 2 and introduce the notation of Cesàro averages for multiple operators in Section 3. We state a general theorem in Section 3 for groups that can be represented by a finite alphabet and a transition matrix. In the second part we show that finitely generated Fuchsian groups, with certain restrictions to the fundamental domain, admit such a representation. To develop the representation we give an introduction into Möbius transformations (Section 4), hyperbolic geometry (Section 5), the concept of Fuchsian groups and their action in the hyperbolic plane (Section 6) and fundamental domains (Section 7). As hyperbolic geometry calls for visualization we included images at various points to make the definitions and statements more approachable. With those tools at hand we can develop a geometrical coding for Fuchsian groups with respect to their fundamental domain in Section 8. Together with the coding we state in Section 9 the main theorem for Fuchsian groups. The last chapter (Section 10) is devoted to the application of the main theorem to three explicit examples. We apply the developed method to the free group F3, to a fundamental group of a compact manifold with genus two and we show why the main theorem does not hold for the modular group PSL(2, Z).:1 Introduction 2 Ergodic Theorems 2.1 Mean Ergodic Theorems 2.2 Pointwise Ergodic Theorems 2.3 The Limit in Ergodic Theorems 3 Cesàro Averages of Sphere Averages 3.1 Basic Notation 3.2 Cesàro Averages as Powers of an Operator 3.3 Convergence of Cesàro Averages 3.4 Invariance of the Limit 3.5 The Limit of Cesàro Averages 3.6 Ergodic Theorems for Strictly Markovian Groups 4 Möbius Transformations 4.1 Introduction and Properties 4.2 Classes of Möbius Transformations 5 Hyperbolic Geometry 5.1 Hyperbolic Metric 5.2 Upper Half Plane and Poincaré Disc 5.3 Topology 5.4 Geodesics 5.5 Geometry of Möbius Transformations 6 Fuchsian Groups and Hyperbolic Space 6.1 Discrete Groups 6.2 The Group PSL(2, R) 6.3 Fuchsian Group Actions on H 6.4 Fuchsian Group Actions on D 7 Geometry of Fuchsian Groups 7.1 Fundamental Domains 7.2 Dirichlet Domains 7.3 Locally Finite Fundamental Domains 7.3.1 Sides of Locally Finite Fundamental Domains 7.3.2 Side Pairings for Locally Finite Fundamental Domains 7.3.3 Finite Sided Fundamental Domains 7.4 Tessellations of Hyperbolic Space 7.5 Example Fundamental Domains 8 Coding for Fuchsian Groups 8.1 Geometric Alphabet 8.1.1 Alphabet Map 8.2 Transition Matrix 8.2.1 Irreducibility of the Transition Matrix 8.2.2 Strict Irreducibility of the Transition Matrix 9 Ergodic Theorem for Fuchsian Groups 10 Example Constructions 10.1 The Free Group with Three Generators 10.1.1 Transition Matrix 10.2 Example of a Surface Group 10.2.1 Irreducibility of the Transition Matrix 10.2.2 Strict Irreducibility of the Transition Matrix 10.3 Example of PSL(2, Z) 10.3.1 Irreducibility of the Transition Matrix 10.3.2 Strict Irreducibility of the Transition Matrix
193

Etude mathématique des problèmes paraboliques fortement anisotropes / Mathematical study of highly anisotropic parabolic problems

Blanc, Thomas 04 December 2017 (has links)
Ce manuscrit de thèse traite de l'analyse asymptotique de problèmes paraboliques possédant des termes raides. Dans un premier temps, on fait l'analyse asymptotique d'un système parabolique possédant des termes de transport raide. Une analyse à deux échelles, basée sur des résultats de théorie ergodique, nous permet de dériver un système limite effectif. Ce système effectif se trouve être, de nouveau, un système parabolique dont le champ de diffusion peut être explicité par une moyenne du champ de diffusion initial le long d'un groupe d'opérateurs unitaires. L'introduction d'un correcteur nous permet d'obtenir un résultat de convergence forte, avec un ordre de convergence, pour des données initiales non nécessairement bien préparées. On propose dans un second temps une méthode numérique permettant de calculer le champ de diffusion effectif. Celle-ci est basée sur la combinaison d'un schéma Runge-Kutta et d'un schéma de type semi-Lagrangien. L'ordre de convergence obtenu théoriquement est mis en évidence de manière numérique. On propose une méthode numérique basée sur un splitting d'opérateur pour la résolution du système parabolique avec termes de transport raide. Enfin, on effectue l'analyse asymptotique d'un système parabolique fortement anisotrope. Sous de bonnes hypothèses de régularité, un système variationnel effectif est proposé et l'introduction d'un correcteur adapté permet d'obtenir un résultat de convergence forte avec un ordre de convergence. Les arguments utilisés relèvent une nouvelle fois de l'analyse à deux échelles et de la théorie ergodique. / This manuscript is devoted to the asymptotic analysis of parabolic equations with stiff terms. First, we perform the asymptotic analysis of a parabolic equation with stiff transport terms. An effective limit model is obtained by a two-scale analysis based on ergodic theory results. This effective system is again a parabolic system whose diffusion field is an average of the initial diffusion field along a group of unitary operators. The introduction of a corrector allows us to obtain a strong convergence result, with an order of convergence, for initial data not necessarily well prepared. We propose a numerical method to compute the effective diffusion field. This method is based on a Runge-Kutta scheme and a semi-Lagrangian scheme. The theoretically order of convergence is obtained numerically. We propose a numerical method based on operator splitting for the resolution of the parabolic system with stiff transport terms. Finally, we perform the asymptotic analysis of a strongly anisotropic parabolic problem. Under suitable smoothness hypotheses, an effective variational system is proposed. By using a suitable corrector, we obtain a strong convergence result and we are able to perform the error analysis. The arguments relate again to the two-scale analysis and the ergodic theory.
194

Optimální řízení stochastických rovnic s Lévyho procesy v Hilbertových proctorech / Optimal control of Lévy-driven stochastic equations in Hilbert spaces

Kadlec, Karel January 2020 (has links)
Controlled linear stochastic evolution equations driven by Lévy processes are studied in the Hilbert space setting. The control operator may be unbounded which makes the results obtained in the abstract setting applicable to parabolic SPDEs with boundary or point control. The first part contains some preliminary technical results, notably a version of Itô formula which is applicable to weak/mild solutions of controlled equations. In the second part, the ergodic control problem is solved: The feedback form of the optimal control and the formula for the optimal cost are found. The control problem is solved in the mean-value sense and, under selective conditions, in the pathwise sense. As examples, various parabolic type controlled SPDEs are studied. 1
195

Operators on wighted spaces of holomorphic functions

Beltrán Meneu, María José 24 March 2014 (has links)
The Ph.D. Thesis ¿Operators on weighted spaces of holomorphic functions¿ presented here treats different areas of functional analysis such as spaces of holomorphic functions, infinite dimensional holomorphy and dynamics of operators. After a first chapter that introduces the notation, definitions and the basic results we will use throughout the thesis, the text is divided into two parts. A first one, consisting of Chapters 1 and 2, focused on a study of weighted (LB)-spaces of entire functions on Banach spaces, and a second one, corresponding to Chapters 3 and 4, where we consider differentiation and integration operators acting on different classes of weighted spaces of entire functions to study its dynamical behaviour. In what follows, we give a brief description of the different chapters: In Chapter 1, given a decreasing sequence of continuous radial weights on a Banach space X, we consider the weighted inductive limits of spaces of entire functions VH(X) and VH0(X). Weighted spaces of holomorphic functions appear naturally in the study of growth conditions of holomorphic functions and have been investigated by many authors since the work of Williams in 1967, Rubel and Shields in 1970 and Shields and Williams in 1971. We determine conditions on the family of weights to ensure that the corresponding weighted space is an algebra or has polynomial Schauder decompositions. We study Hörmander algebras of entire functions defined on a Banach space and we give a description of them in terms of sequence spaces. We also focus on algebra homomorphisms between these spaces and obtain a Banach-Stone type theorem for a particular decreasing family of weights. Finally, we study the spectra of these weighted algebras, endowing them with an analytic structure, and we prove that each function f ¿ VH(X) extends naturally to an analytic function defined on the spectrum. Given an algebra homomorphism, we also investigate how the mapping induced between the spectra acts on the corresponding analytic structures and we show how in this setting composition operators have a different behavior from that for holomorphic functions of bounded type. This research is related to recent work by Carando, García, Maestre and Sevilla-Peris. The results included in this chapter are published by Beltrán in [14]. Chapter 2 is devoted to study the predual of VH(X) in order to linearize this space of entire functions. We apply Mujica¿s completeness theorem for (LB)-spaces to find a predual and to prove that VH(X) is regular and complete. We also study conditions to ensure that the equality VH0(X) = VH(X) holds. At this point, we will see some differences between the finite and the infinite dimensional cases. Finally, we give conditions which ensure that a function f defined in a subset A of X, with values in another Banach space E, and admitting certain weak extensions in a space of holomorphic functions can be holomorphically extended in the corresponding space of vector-valued functions. Most of the results obtained have been published by the author in [13]. The rest of the thesis is devoted to study the dynamical behaviour of the following three operators on weighted spaces of entire functions: the differentiation operator Df(z) = f (z), the integration operator Jf(z) = z 0 f(¿)d¿ and the Hardy operator Hf(z) = 1 z z 0 f(¿)d¿, z ¿ C. In Chapter 3 we focus on the dynamics of these operators on a wide class of weighted Banach spaces of entire functions defined by means of integrals and supremum norms: the weighted spaces of entire functions Bp,q(v), 1 ¿ p ¿ ¿, and 1 ¿ q ¿ ¿. For q = ¿ they are known as generalized weighted Bergman spaces of entire functions, denoted by Hv(C) and H0 v (C) if, in addition, p = ¿. We analyze when they are hypercyclic, chaotic, power bounded, mean ergodic or uniformly mean ergodic; thus complementing also work by Bonet and Ricker about mean ergodic multiplication operators. Moreover, for weights satisfying some conditions, we estimate the norm of the operators and study their spectrum. Special emphasis is made on exponential weights. The content of this chapter is published in [17] and [15]. For differential operators ¿(D) : Bp,q(v) ¿ Bp,q(v), whenever D : Bp,q(v) ¿ Bp,q(v) is continuous and ¿ is an entire function, we study hypercyclicity and chaos. The chapter ends with an example provided by A. Peris of a hypercyclic and uniformly mean ergodic operator. To our knowledge, this is the first example of an operator with these two properties. We thank him for giving us permission to include it in our thesis. The last chapter is devoted to the study of the dynamics of the differentiation and the integration operators on weighted inductive and projective limits of spaces of entire functions. We give sufficient conditions so that D and J are continuous on these spaces and we characterize when the differentiation operator is hypercyclic, topologically mixing or chaotic on projective limits. Finally, the dynamics of these operators is investigated in the Hörmander algebras Ap(C) and A0 p(C). The results concerning this topic are included by Bonet, Fernández and the author in [16]. / Beltrán Meneu, MJ. (2014). Operators on wighted spaces of holomorphic functions [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/36578 / TESIS / Premios Extraordinarios de tesis doctorales
196

Asymptotic Formula for Counting in Deterministic and Random Dynamical Systems

Naderiyan, Hamid 05 1900 (has links)
The lattice point problem in dynamical systems investigates the distribution of certain objects with some length property in the space that the dynamics is defined. This problem in different contexts can be interpreted differently. In the context of symbolic dynamical systems, we are trying to investigate the growth of N(T), the number of finite words subject to a specific ergodic length T, as T tends to infinity. This problem has been investigated by Pollicott and Urbański to a great extent. We try to investigate it further, by relaxing a condition in the context of deterministic dynamical systems. Moreover, we investigate this problem in the context of random dynamical systems. The method for us is considering the Fourier-Stieltjes transform of N(T) and expressing it via a Poincaré series for which the spectral gap property of the transfer operator, enables us to apply some appropriate Tauberian theorems to understand asymptotic growth of N(T). For counting in the random dynamics, we use some results from probability theory.
197

Information Theoretical Studies on MIMO Channel with Limited Channel State Information

Abdelaziz, Amr Mohamed January 2017 (has links)
No description available.
198

Achievable Rate and Capacity of Amplify-and-Forward Multi-Relay Networks with Channel State Information

Tran, Tuyen X. 20 September 2013 (has links)
No description available.
199

On the Problem of Arbitrary Projections onto a Reduced Discrete Set of States with Applications to Mean First Passage Time Problems

Biswas, Katja 09 December 2011 (has links)
This dissertation presents a theoretical study of arbitrary discretizations of general nonequilibrium and non-steady-state systems. It will be shown that, without requiring the partitions of the phase-space to fulfill certain assumptions, such as culminating in Markovian partitions, a Markov chain can be constructed which has the same macro-change of probability of the occupation of the states as the original process. This is true for any classical and semiclassical system under any discrete or continuous, deterministic or stochastic, Markovian or non-Markovian dynamics. Restricted to classical and semi-classical systems, a formalism is developed which treats the projection of arbitrary (multidimensional) complex systems onto a discrete set of states of an abstract state-space using time and ensemble sampled transitions between the states of the trajectories of the original process. This formalism is then used to develop expressions for the mean first passage time and (in the case of projections resulting in pseudo-one-dimensional motion) for the individual residence times of the states using just the time and ensemble sampled transition rates. The theoretical work is illustrated by several numerical examples of non-linear diffusion processes. Those include the escape over a Kramers potential and a rough energy barrier, the escape from an entropic barrier, the folding process of a toy model of a linear polymer chain and the escape over a fluctuating barrier. The latter is an example of a non- Markovian dynamics of the original process. The results for the mean first passage time and the residence times (using both physically meaningful and non-meaningful partitions of the phase-space) confirms the theory. With an accuracy restricted only by the resolution of the measurement and/or the finite sampling size, the values of the mean first passage time of the projected process agree with those of a direct measurement on the original dynamics and with any available semi-analytical solution.
200

Essays on the dynamics of cross-country income distribution and intra-household time allocation

Hites, Gisèle 12 September 2007 (has links)
This thesis contributes to two completely unrelated debates in the economic literature, similar only in the relatively high degree of controversy characterizing each one. <p>The first part is methodological and macroeconomic in nature, addressing the question of whether the distribution of income across countries is converging (i.e. are the poor catching up to the rich?) or diverging (i.e. are we witnessing the formation of two exclusive clubs, one for poor countries and another one for rich countries?). Applications of the simple Markov model to this question have generated evidence in favor of the divergence hypothesis. In the first chapter, I critically review these results. I use statistical inference to show that the divergence results are not statistically robust, and I explain that this instability of the results comes from the application of a model for discrete data to data that is actually continuous. In the second chapter, I reposition the whole convergence-divergence debate by placing it in the context of Silverman’s classic survey of non-parametric density estimation techniques. This allows me to use the basic notions of fuzzy logic to adapt the simple Markov chain model to continuous data. When I apply the newly adapted Markov chain model to the cross-country distribution question, I find evidence against the divergence hypothesis, and this evidence is statistically robust. <p>The second part of the thesis is empirical and microeconomic in nature. I question whether observed differences between husbands’ and wives’ participation in labor markets are due to different preferences or to different constraints. My identification strategy is based on the idea that the more power an individual has relative to his/her partner, the more his/her actions will reflect his/her preferences. I use 2001 PSID data on cohabiting couples to estimate a simultaneous equations model of the spousal time allocation decision. My results confirm the stylized fact that specialization and trade does not explain time allocation for couples in which the wife is the primary breadwinner, and suggest that power could provide a more general explanation of the observations. My results show that wives with relatively more power choose to work more on the labor market and less at home, whereas husbands with more power choose to do the opposite. Since women start out from a lower level of labor market participation than men do, it would seem that spouses’ agree that the ideal mix of market work and housework lies somewhere between the husbands’ and the wives’ current positions. / Doctorat en sciences économiques, Orientation économie / info:eu-repo/semantics/nonPublished

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