Global ETD Search

1	Accuracy of Computer Generated Approximations to Julia Sets Hoggard, John W. 17 August 2000 (has links) A Julia set for a complex function 𝑓 is the set of all points in the complex plane where the iterates of 𝑓 do not form a normal family. A picture of the Julia set for a function can be generated with a computer by coloring pixels (which we consider to be small squares) based on the behavior of the point at the center of each pixel. We consider the accuracy of computer generated pictures of Julia sets. Such a picture is said to be accurate if each colored pixel actually contains some point in the Julia set. We extend previous work to show that the pictures generated by an algorithm for the family λe² are accurate, for appropriate choices of parameters in the algorithm. We observe that the Julia set for meromorphic functions with polynomial Schwarzian derivative is the closure of those points which go to infinity under iteration, and use this as a basis for an algorithm to generate pictures for such functions. A pixel in our algorithm will be colored if the center point becomes larger than some specified bound upon iteration. We show that using our algorithm, the pictures of Julia sets generated for the family λtan(z) for positive real λ are also accurate. We conclude with a cautionary example of a Julia set whose picture will be inaccurate for some apparently reasonable choices of parameters, demonstrating that some care must be exercised in using such algorithms. In general, more information about the nature of the function may be needed. / Ph. D. tangent meromorphic computer algorithms polynomial Schwarzian derivative Julia sets
2	Isospectral graph reductions, estimates of matrices' spectra, and eventually negative Schwarzian systems Webb, Benjamin Zachary 18 March 2011 (has links) This dissertation can be essentially divided into two parts. The first, consisting of Chapters I, II, and III, studies the graph theoretic nature of complex systems. This includes the spectral properties of such systems and in particular their influence on the systems dynamics. In the second part of this dissertation, or Chapter IV, we consider a new class of one-dimensional dynamical systems or functions with an eventual negative Schwarzian derivative motivated by some maps arising in neuroscience. To aid in understanding the interplay between the graph structure of a network and its dynamics we first introduce the concept of an isospectral graph reduction in Chapter I. Mathematically, an isospectral graph transformation is a graph operation (equivalently matrix operation) that modifies the structure of a graph while preserving the eigenvalues of the graphs weighted adjacency matrix. Because of their properties such reductions can be used to study graphs (networks) modulo any specific graph structure e.g. cycles of length n, cliques of size k, nodes of minimal/maximal degree, centrality, betweenness, etc. The theory of isospectral graph reductions has also lead to improvements in the general theory of eigenvalue approximation. Specifically, such reductions can be used to improved the classical eigenvalue estimates of Gershgorin, Brauer, Brualdi, and Varga for a complex valued matrix. The details of these specific results are found in Chapter II. The theory of isospectral graph transformations is then used in Chapter III to study time-delayed dynamical systems and develop the notion of a dynamical network expansion and reduction which can be used to determine whether a network of interacting dynamical systems has a unique global attractor. In Chapter IV we consider one-dimensional dynamical systems of an interval. In the study of such systems it is often assumed that the functions involved have a negative Schwarzian derivative. Here we consider a generalization of this condition. Specifically, we consider the functions which have some iterate with a negative Schwarzian derivative and show that many known results generalize to this larger class of functions. This includes both systems with regular as well as chaotic dynamic properties. Schwarzian derivative Global stability Dynamical networks Spectral equivalence Graph transformations Complex matrices Attractors (Mathematics) Eigenvalues
3	[pt] COMPORTAMENTO ESTATÍSTICO DE PRODUTOS TORTOS: DERIVADA SCHWARZIANA E LEIS DO ARCO-SENO / [en] STATISTICAL BEHAVIOR OF SKEW PRODUCTS: SCHWARZIAN DERIVATIVE AND ARC-SINE LAWS RAUL STEVEN RODRIGUEZ CHAVEZ 11 June 2024 (has links) [pt] Consideramos produtos tortos sobre shifts de Bernoulli, cuja dinâmica fibrada é dada por difeomorfismos do intervalo. Estudamos o comportamento previsível e/ou histórico destes sistemas, referindo-nos à convergência e/ou não convergência, da média de Birkhoff, respectivamente. Utilizamos a derivada Schwarziana das fibras e a lei do arco-seno para identificar condições nas quais esses produtos tortos apresentam esses tipos de comportamento. Identificamos distintos tipos de comportamento em relação à derivada Schwarziana. Quando a derivada Schwarziana é negativa, o produto torto tem bacias entrelaçadas. Por outro lado, quando a derivada Schwarziana é positiva, o produto torto possui uma medida física. Finalmente, quando a derivada Schwarziana é nula, o produto torto tem comportamento histórico. No último cenário, estabelecemos uma conexão entre o comportamento histórico e a lei do arco-seno que nos permite obter resultados em outras configurações independentes do sinal da derivada Schwarziana. / [en] We consider skew products over Bernoulli shifts, whose fibred dynamics is given by diffeomorphisms of the interval. We study the predictable and/or historical behavior, referring to convergence and/or non-convergence, of the Birkhoff average, respectively. We employ the Schwarzian derivative of the fiber maps and the arc-sine law to identify conditions under which these skew products exhibit these types of behavior. We identify distinct types of behavior according to the Schwarzian derivative. When the Schwarzian derivative is negative, the skew product has intermingled basins. Conversely, when the Schwarzian derivative is positive, the skew product has a physical measure. Finally, when the Schwarzian derivative is zero, the skew product has historical behavior. In the latter scenario, we establish a connection between historical behavior and the arc-sine law that allows us to obtain results in other settings independent of the sign of the Schwarzian derivative. [pt] BACIAS ENTRELACADAS [pt] LEI DO ARCO-SENO [pt] DERIVADA SCHWARZIANA [pt] COMPORTAMENTO HISTORICO [pt] MEDIDA FISICA [en] INTERMINGLED BASINS [en] ARC-SINE LAW [en] SCHWARZIAN DERIVATIVE [en] HISTORICAL BEHAVIOR [en] PHYSICAL MEASURE
4	On multifractality, Schwarzian derivative and asymptotic variance of whole-plane SLE / Sur la mutifractalité, la dérivée schwarziene et la variance asymptotique de whole-plane SLE Ho, Xuan Hieu 05 December 2016 (has links) Soit f une instance du whole-plane $\SLE_\kappa$ : on sait que pour certaines valeurs de κ, p les moments dérivés $\mathbb{E}(\vert f'(z) \vert^p)$ peuvent être écrits sous une forme fermée, étude qui a permis de mettre au jour une nouvelle phase du spectre des moyennes intégrales. Le but de cette thèse est une étude des moments généralisés $\frac{\vert f'(z) \vert^p}{\vert f(z) \vert^q}$ : cette étude permet de confirmer la structure algébrique riche du whole-plane SLE. On montre que les formes fermées des moments mixtes $\mathbb{E}\big(\frac{\vert f'(z) \vert^p}{\vert f(z) \vert^q}\big)$ apparaissent sur une famille dénombrable de paraboles du plan (p, q), en étendant les équations de Beliaev-Smirnov à ce cas. Nous introduisons également le spectre généralisé β(p, q; κ), correspondant au comportement asymptotiques des moyennes intégrales mixtes. Le spectre généralisé moyen du whole-plane SLE prend quatre formes possibles, séparés par cinq séparatrices dans $\R^2$. Nous proposons également une approche semblable pour la dérivée Schwarziene S(f)(z) de l’application de SLE. Les calculs sur les équations de Beliaev-Smirnov d’une certaine générale forme de moment mène à une formulation explicite de $\mathbb{E}(S(f)(z))$ . Nous étudions finalement la variance asymptotique de McMullen et démontrons une relation entre la croissance infinitésimale du spectre de la moyenne intégrale et la variance asymptotique pour SLE₂. / Let f an instance of the whole-plane $\SLE_\kappa$ conformal map from the unit disk D to the slit plane: We know that for certain values of κ, p the derivative moments $\mathbb{E}(\vert f'(z) \vert^p)$ can be written in a closed form, study that has updated a new phase of the integral means spectrum. The goal of this thesis is a study on generalized moments $\frac{\vert f'(z) \vert^p}{\vert f(z) \vert^q}$ : ΒββThis study permit confirm the rich algebraic structure of the whole-plane version of SLE. It will be showed that closed forms of the mixed moments E mixtes $\mathbb{E}\big(\frac{\vert f'(z) \vert^p}{\vert f(z) \vert^q}\big)$ can be obtained on a countable family of parabolas in the moment plane (p, q), by extending the so-called Beliaev–Smirnov equation to this case. We also introduce the generalized integral means spectrum, β(p, q; κ), corresponding to the singular behavior of the mixed moments. The average generalized spectrum of whole-plane SLE takes four possible forms, separated by five phase transition lines in $\R^2$. We also propose a similar approach for the Schwarzian derivative S(f)(z) of SLE maps. Computations on the Beliaev–Smirnov equation of a certain general form of moment lead to an explicit formula of $\mathbb{E}(S(f)(z))$ . We finally study the McMullen asymptotic variance and prove a relation between the infinitesimal growth of the integral mean spectrum and the asymptotic variance in an expectation sense for SLE₂. Whole-plane SLE Moment logarithmique Equation de Beliaev-Smirnov Spectre de la moyenne intégrale Dérivée Schwarziene Variance asymptotique de McMullen Whole-plane SLE Logarithmic moment Beliaev-Smirnov equation Generalized integral means spectrum Schwarzian derivative McMullen’s asymptotic variance 514.742
5	Quantum gravity in two- and three-dimensional dS spaces Chernichenko, Alexsey January 2024 (has links) This thesis is a study of certain aspects of quantum gravity in two- and three-dimensional de Sitter spaces. The model used in dS2 is the Jackiw- Tetitelboim gravity which involves a scalar coupling. At low-energy limit this model becomes Schwarzian theory for which one can compute one-loop partition function. Along the way, the model is recasted into the first order formalism which helps to find an appropriate measure for the partition function. The layout for quantum gravity in dS3 is practically the same and many results appear to be quite similar. Although, there are as many dissimilarities. Ultimately, the goal is different, namely to determine one-loop correction to the central charge of the theory dual to dS3 . Additionally, a putative genus expansion for Jackiw-Teitelboim gravity is investigated along with some concrete computations being done. / Detta examensarbete ̈ar en studie av vissa aspekter av kvantgravita-tion i två och tredimensionella de Sitter-rummen. Den behandlar Jackiw-Teitelboim gravitation i dS2 , en model med en skalär koppling. Vid lågenergigränns blir modellen till Schwarzian teorin som används för att beräkna första ordningskorrektionen till partitionsfunktion. På vägen dit skrivs om modelen till första ordningens formalism som sedan hjälper att hitta ett lämpligt mått för partitionsfunktionen. Plannen för dS3 ser ut i princip likadant och en stor del av resultater är liknande. Emellertid finns det lika många olikheter. I slut änden, målet är annorludna, nämligen att beräkna första ordningens korrektion till centrala laddningen av teorin som dual till dS3 . Dessutom, en förmodad genus expansion för Jackiw-Teitelboim gravitation är undersökt och vissa konkreta beräkningar är gjorda. Gravity Quantum gravity de Sitter space Jackiw-Teitelboim gravity Hartle-Hawking wavefunction of the Universe Wheeler-DeWitt equation Gravitational path integral Partition function Dilaton Gibbons-Hawking-York term Schwarzian theory Flat connections Space of flat connections Symplectic form Symplectic measure Holonomy Monodromy Genus expansion Weil-Peterson volumes Mirzakhani's recursion formula Central charge Chern-Simons theory Wess-Zumino-Witten model Natural Sciences Naturvetenskap Physical Sciences Fysik
6	Feigenbaum Scaling Sendrowski, Janek January 2020 (has links) In this thesis I hope to provide a clear and concise introduction to Feigenbaum scaling accessible to undergraduate students. This is accompanied by a description of how to obtain numerical results by various means. A more intricate approach drawing from renormalization theory as well as a short consideration of some of the topological properties will also be presented. I was furthermore trying to put great emphasis on diagrams throughout the text to make the contents more comprehensible and intuitive. Feigenbaum Feigenbaum constant Feigenbaum point superstable self-similarity fractals final-state diagram logistic map period-doubling operator linearized period-doubling operator Cantor set Sharkovsky sequence Chebyshev interpolation stable manifold unstable manifold orbits fixed points scaling factor pitchfork bifurcation cobweb plot renormalization iterates one-hump map unimodal map bifurcation cascade Feigenbaum universality chaos theory spectrum generalized Feigenvalues bifurcation points superstable points fixed function universal function eigenvalues eigenvectors eigenfunctions universality conditions Schwarzian derivative Newton’s method power method Arnoldi’s method attractive fixed point repellent fixed point Banach fixed-point theorem collocation method functional analysis topology Mathematical Analysis Matematisk analys Other Mathematics Annan matematik Computational Mathematics Beräkningsmatematik

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