An important part of the study of dynamical systems is the fitting of models to time-series data. That is, given the data, a series of observations taken from a (not fully understood) system of interest, we would like to specify a model, a mathematical system which generates a sequence of “simulated” observations. Our aim is to obtain a “good” model — one that is in agreement with the data. We would like this agreement to be quantitative — not merely qualitative. The major subject of this thesis is the question of what good quantitative agreement means. Most approaches to this question could be described as “predictionist”. In the predictionist approach one builds models by attempting to answer the question, “given that the system is now here, where will it be next?” The quality of the model is judged by the degree to which the states of the model and the original system agree in the near future, conditioned on the present state of the model agreeing with that of the original system. Equivalently, the model is judged on its ability to make good short-term predictions on the original system. The main claim of this thesis is that prediction is often not the most appropriate criterion to apply when fitting models. We show, for example, that one can have models that, while able to make good predictions, have long term (or free-running) behaviour bearing little resemblance to that exhibited in the original time-series. We would hope to be able to use our models for a wide range of purposes other than just prediction — certainly we would like our models to exhibit good free-running behaviour. This thesis advocates a “behaviourist” approach, in which the criterion for a good model is that its long-term behaviour matches that exhibited by the data. We suggest that the behaviourist approach enjoys a certain robustness over the predictionist approaches. We show that good predictors can often be very poorly behaved, and suggest that well behaved models cannot perform too badly at the task of prediction. The thesis begins by comparing the predictionist and behaviourist approaches in the context of a number of simplified model-building problems. It then presents a simple theory for the understanding of the differences between the two approaches. Effective methods for the construction of well-behaved models are presented. Finally, these methods are applied to two real-world problems — modelling of the response of a voltage-clamped squid “giant” axon, and modelling of the “yearly sunspot number”.

Techn. Univ., Diss.--Hamburg-Harburg, 2002.

Thesis (Ph. D.)--Physics, Georgia Institute of Technology, 2005. / Jean Bellissard, Committee Member ; Turgay Uzer, Committee Member ; Roman Grigoriev, Committee Member ; Konstantin Mischaikow, Committee Member ; Predrag Cvitanovic, Committee Chair. Vita. Includes bibliographical references.

Thesis (Honors)--College of William and Mary, 2009. / Includes bibliographical references (leaves 56-57). Also available via the World Wide Web.

Thesis (Ph. D.)--University of Chicago, Dept. of Physics, December 1997. / Includes bibliographical references. Also available on the Internet.

Thesis (M. Phil.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Made available in DSpace on 2014-06-11T19:26:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-18Bitstream added on 2014-06-13T20:16:03Z : No. of bitstreams: 1 alves_ff_me_sjrp.pdf: 362207 bytes, checksum: 9a797ca400dea6e139af98c5a9f10378 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este trablaho apresenta os conceitos de Lyapounov e de espaços próprios e fornece um resultado devido a Oseledets, o qual trata da existência desses expoentes (e, consequentemente, dos espaços próprios) do ponto de vista da teoria da medida. A prova do teorema que nós fornecemos foi dada originalmente por Mañe e posteriormente melhorada por Viana. / This work presents the concepts of Lyapounov exponents and of proper spaces and provides a result due to Oseledets, wich deals with the existence of these exponents (and consequently, of the proper spaces) from a measure-theoretical point of view. The proof of the theorem which we provide was originally given by Mañe later improved by Viana.

Made available in DSpace on 2014-06-11T19:26:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-18Bitstream added on 2014-06-13T20:16:04Z : No. of bitstreams: 1 pavani_ga_me_sjrp.pdf: 401034 bytes, checksum: b8453144d792a7550e9f766d6bfc9fd8 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo deste trabalho é estudar propriedades topológicas e aritméticas dos fractais de Rauzy. Em particular provamos que o fractal de Rauzy é um subconjunto compacto de C, conexo, com interior simplesmente conexo e que ele induz um azulejamento periódico do plano complexo. Além disso, construimos um autômato finito capaz de gerar a fronteira do fractal de Rauzy. Com isto demos uma parametrização para a fronteira e claculamos sus dimensão de Hausdorff. Estudamos também os pontos extremos do fractal de Rauzy. / The aim of this work is to study some topological and arithmetical properties of the Rauzy fractals. In particular we proved that the Rauzy fractal is a compact subset of C, connected, its interior is simply connected, and it induces a periodic tiling of the complex pane. Furthermore, we studied the construction of a finite automaton able to generate the boundary of the Rauzy fractal, allowing us to provide a parametrization for its boundary, and claculate its Hausdorff dimension. We also studied the extremal points of the Rauzy fractal.

Made available in DSpace on 2014-06-11T19:26:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-06-26Bitstream added on 2014-06-13T20:08:05Z : No. of bitstreams: 1 tambellini_l_me_sjrp.pdf: 1124234 bytes, checksum: 8cc4df0d667724def74ec4f0b65c3020 (MD5) / Neste trabalho abordamos um tema introdutório na interseção de duas áreas da Matemáticas, Sistemas Dinâmicos e Teoria dos Números. Através de um jogo aparentemente ingênuo, a Paciência Búlgara, estudamos dinâmicas em conjuntos finitos. Devidoà finitude do domínio, todos os pontos do sistema convergem para uma órbita periódica, mas interessante é saber quantas órbitas distintas o sistema apresenta em função da quantidade de elementos do domínio. Outra pergunta natural é sobre o tempo de convergência a estas órbitas. Estudamos também uma variação deste jogo, a Paciência Carolina / This work refers to a introductory topic in the intersection of two areas in Mathematics, Dynam-ical Systems and Number Theory. Motivated to a game seemingly naive, Bulgarian Solitaire, we study dynamics in finite sets. Due to the finiteness of the domain,all points of the sys-tem converge to a periodic orbit, but it is interesting to know how many distinct orbits the system displays depending on the size of the domain. Another natural question is about the convergence time of these orbits. We also study a variation of this game, Carolina Solitaire

Made available in DSpace on 2014-06-11T19:26:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2001-12-11Bitstream added on 2014-06-13T20:47:37Z : No. of bitstreams: 1 pereira_wf_me_sjrp.pdf: 614166 bytes, checksum: 6df9d771c65c6fa8d098e4e0aba88fb5 (MD5) / Neste trabalho estudamos os sistemas dinâmicos caóticos através da definição apresentada por Devaney, composta basicamente de três condições. Investigamos todas as implicações possíveis entre essas condições. Por fim, analisamos o estudo apresentando uma definição mais sucinta e provamos a sua equivalência com a apresentada por Devaney. / In this work we study the chaotic dynamic systems through the definition presented by Devaney, basically composed of three conditions. We investigate all the possible implications among these conditions. Finally, we finish the study presenting briefer definition and prove its equivalence to the one presented by Devaney.