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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.
21

Comportamento genérico de difeomorfismos do círculo / Generic behavior of circle diffeomorphisms

Leandro Antunes 23 February 2012 (has links)
Nós estudaremos o comportamento de difeomorfismos do círculo, tanto do ponto de vista combinatório quanto do ponto de vista topológico e da teoria da medida, seguindo os trabalhos de Michael Herman. A cada homeomorfismo do círculo podemos associar um número real positivo, denominado número de rotação. Mostraremos que existe um conjunto de números irracionais de medida de Lebesgue total na reta tal que, se f é um difeomorfismo do círculo de classe \'C POT. r \' que preserva a orientação, com r maior ou igual a 3 e com número de rotação nesse conjunto, então f é pelo menos \'C POT. r - 2\' -conjugada a uma translação irracional. Além disso, mostraremos que dado um caminho \'f IND. t\' de classe \'C POT. 1\' definido em um intervalo [a;b] no conjunto dos difeomorfismos do círculo de classe \'C POT. r\' que preservam a orientação, com r maior ou igual a 3, o conjunto dos parâmetros em que \'f IND. t\' é \'C POT. r - 2\' -conjugada a uma translação irracional tem medida de Lebesgue positiva, desde que os números de rotação em \'f IND. a\' e \'f IND. b\' sejam distintos / We will study the generic behavior of circle diffeomorphisms, in the combinatorial, topological and measure-theoretical sense, following the work of Michael Herman. To each order preserving homeomorphism of the circle we can associate a positive real number, called rotation number, which is invariant under conjugacy. We will show that there is a set of irrational numbers with full Lebesgue measure on R such that, if f is a circle diffeomorphism of class \'C POT. r\', with r greater or equal 3 and with rotation number in that set, then f is at least \'C POT. r - 2\' -conjugated to an irrational translation. Moreover, we will show that if ft is a \'C POT. 1\' -path defined on a interval [a;b] over the set of the circle diffeomorphisms orientation preserving, with r \'> or =\' 3, then the set of parameters where \'f IND. t\' is \'C POT. r - 2\' -conjugated to a irrational translation has positive Lebesgue measure, since the rotation numbers of \'f IND. a\' and \'f IND. b\' are distinct
22

Proposta de constelações de sinais para o codigo genetico / Proposal of signal constellations for the genetic code

Albuquerque, Julio Cesar Holanda de 12 August 2018 (has links)
Orientador: Reginaldo Palazzo Junior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-12T13:34:06Z (GMT). No. of bitstreams: 1 Albuquerque_JulioCesarHolandade_M.pdf: 1364323 bytes, checksum: 01181adde228aa4d914d7edabdde4aca (MD5) Previous issue date: 2008 / Resumo: A proposta deste trabalho é apresentar uma abordagem aos processos genéticos e moleculares, utilizando a teoria de comunicações e codificação na modelagem do dogma central da biologia molecular. A partir desta modelagem associamos o código genético a um modulador de um sistema de comunicação. Mais especificamente, tal procedimento consiste em construir uma constelação de sinais a partir dos subgrupos de S3 e S4 baseado no código genético. Considerando este método algébrico de construção de sinais, propomos duas possíveis constelações de sinais para o código genético. A representação do código genético em constelações de sinais correlacionadas deu origem à idéia de "constelação de sinais concatenadas", idéia inovadora na teoria de comunicação e codificação. As constelações de sinais concatenadas possui a propriedade de correção de erros, consistindo de novos conceitos úteis para utilização na teoria da comunicação e codificação. Por outro lado, estas representações do código genético não são únicas pois, até o presente momento, desconhecemos uma álgebra que descreva o código genético juntamente com as suas partições geradas pelos aminoácidos. / Abstract: The purpose of this work is to present an approach to the genetic and molecular processes by use of the communication and coding theory in modelling the central dogma of the molecular biology. From this modelling we associate the genetic code to a modulator in the communication system. More specifically, such a procedure consists is in the construction of a signal constellation by use of the S3 and S4 permutation subgroups based on the code genetic. By considering this algebraic method of signal design, we propose two possible signal constellations to the genetic code. The representation of the genetic code as correlated signal constellations provides the idea idea of "concatenated signal constellation", an innovative idea in communication and coding theory. The concatenated signal constellations have the property of error-correction, a new concept being introduced. On the other hand, these representations of the genetic code are not unique for currently, we do not know an algebraic structure capable of describing the genetic code together with the partitioning generated by the amino acids. / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica
23

Dynamics for a Random Differential Equation: Invariant Manifolds, Foliations, and Smooth Conjugacy Between Center Manifolds

Zhao, Junyilang 01 April 2018 (has links)
In this dissertation, we first prove that for a random differential equation with the multiplicative driving noise constructed from a Q-Wiener process and the Wiener shift, which is an approximation to a stochastic evolution equation, there exists a unique solution that generates a local dynamical system. There also exist a local center, unstable, stable, centerunstable, center-stable manifold, and a local stable foliation, an unstable foliation on the center-unstable manifold, and a stable foliation on the center-stable manifold, the smoothness of which depend on the vector fields of the equation. In the second half of the dissertation, we show that any two arbitrary local center manifolds constructed as above are conjugate. We also show the same conjugacy result holds for a stochastic evolution equation with the multiplicative Stratonovich noise term as u â—¦ dW
24

Triple generations of the Lyons sporadic simple group

Motalane, Malebogo John 03 1900 (has links)
The Lyons group denoted by Ly is a Sporadic Simple Group of order 51765179004000000 = 28 37 56 7 11 31 37 67. It(Ly) has a trivial Schur Multiplier and a trivial Outer Automorphism Group. Its maximal subgroups are G2(5) of order 5859000000 and index 8835156, 3 McL:2 of order 5388768000 and index 9606125, 53 L3(5) of order 46500000 and index 1113229656, 2 A11 of order 29916800 and index 1296826875, 51+4 + :4S6 of order 9000000 and index 5751686556, 35:(2 M11) of order 3849120 and index 13448575000, 32+4:2 A5 D8 of order 699840 and index 73967162500, 67:22 of order 1474 and index 35118846000000 and 37:18 of order 666 and index 77725494000000. Its existence was suggested by Richard Lyons. Lyons characterized its order as the unique possible order of any nite simple group where the centralizer of some involution is isomorphic to the nontrivial central extension of the alternating group of degree 11 by the cyclic group of order 2. Sims proved the existence of this group and its uniqueness using permutations and machine calculations. In this dissertation, we compute the (p; q; t)-generations of the Lyons group for dis- tinct primes p, q and t which divide the order of Ly such that p < q < t. For computations, we made use of the Computer Algebra System GAP / Mathematical Sciences / M.Sc. (Mathematics)
25

Problème inverse de Galois : critère de rigidité

Amalega Bitondo, François 08 1900 (has links)
Dans ce mémoire, on étudie les extensions galoisiennes finies de C(x). On y démontre le théorème d'existence de Riemann. Les notions de rigidité faible, rigidité et rationalité y sont développées. On y obtient le critère de rigidité qui permet de réaliser certains groupes comme groupes de Galois sur Q. Plusieurs exemples de types de ramification sont construis. / In this master thesis we study finite Galois extensions of C(x). We prove Riemann existence theorem. The notions of rigidity, weak rigidity, and rationality are developed. We obtain the rigidity criterion which enable us to realise some groups as Galois groups over Q. Many examples of ramification types are constructed.
26

Characterization of the unfolding of a weak focus and modulus of analytic classification

Arriagada Silva, Waldo G. 06 1900 (has links)
La thèse présente une description géométrique d’un germe de famille générique déployant un champ de vecteurs réel analytique avec un foyer faible à l’origine et son complexifié : le feuilletage holomorphe singulier associé. On montre que deux germes de telles familles sont orbitalement analytiquement équivalents si et seulement si les germes de familles de difféomorphismes déployant la complexification de leurs fonctions de retour de Poincaré sont conjuguées par une conjugaison analytique réelle. Le “caractère réel” de la famille correspond à sa Z2-équivariance dans R^4, et cela s’exprime comme l’invariance du plan réel sous le flot du système laquelle, à son tour, entraîne que l’expansion asymptotique de la fonction de Poincaré est réelle quand le paramètre est réel. Le pullback du plan réel après éclatement par la projection monoidal standard intersecte le feuilletage en une bande de Möbius réelle. La technique d’éclatement des singularités permet aussi de donner une réponse à la question de la “réalisation” d’un germe de famille déployant un germe de difféomorphisme avec un point fixe de multiplicateur égal à −1 et de codimension un comme application de semi-monodromie d’une famille générique déployant un foyer faible d’ordre un. Afin d’étudier l’espace des orbites de l’application de Poincaré, nous utilisons le point de vue de Glutsyuk, puisque la dynamique est linéarisable auprès des points singuliers : pour les valeurs réels du paramètre, notre démarche, classique, utilise une méthode géométrique, soit un changement de coordonée (coordonée “déroulante”) dans lequel la dynamique devient beaucoup plus simple. Mais le prix à payer est que la géométrie locale du plan complexe ambiante devient une surface de Riemann, sur laquelle deux notions de translation sont définies. Après avoir pris le quotient par le relèvement de la dynamique nous obtenons l’espace des orbites, ce qui s’avère être l’union de trois tores complexes plus les points singuliers (l’espace résultant est non-Hausdorff). Les translations, le caractère réel de l’application de Poincaré et le fait que cette application est un carré relient les différentes composantes du “module de Glutsyuk”. Cette propriété implique donc le fait qu’une seule composante de l’invariant Glutsyuk est indépendante. / The thesis gives a geometric description for the germ of the singular holomorphic foliation associated with the complexification of a germ of generic analytic family unfolding a real analytic vector field with a weak focus at the origin. We show that two such germs of families are orbitally analytically equivalent if and only if the germs of families of diffeomorphisms unfolding the complexified Poincaré map of the singularities are conjugate by a real analytic conjugacy. The Z2-equivariance of the family of real vector fields in R^4 is called the “real character” of the system. It is expressed by the invariance of the real plane under the flow of the system which, in turn, carries the real asymptotic expansion of the Poincaré map when the parameter is real. After blowing up the singularity, the pullback of the real plane by the standard monoidal map intersects the foliation in a real Möbius strip. The blow up technique allows to “realize” a germ of generic family unfolding a germ of diffeomorphism of codimension one and multiplier −1 at the origin as the semi-monodromy of a generic family unfolding an order one weak focus. In order to study the orbit space of the Poincaré map, we perform a trade-off between geometry and dynamics under the Glutsyuk point of view (where the dynamics is linearizable near the singular points): in the resulting “unwrapping coordinate” the dynamics becomes much simpler, but the price we pay is that the local geometry of the ambient complex plane turns into a much more involved Riemann surface. Over the latter, two notions of translations are defined. After taking the quotient by the lifted dynamics we get the orbit space, which turns out to be the union of three complex tori and the singular points (this space is non- Hausdorff). The Glutsyuk invariant is then defined over annular-like regions on the tori. The translations, the real character and the fact that the Poincaré map is the square of the semi-monodromy map, relate the different components of the Glutsyuk modulus. That property yields only one independent component of the Glutsyuk invariant.
27

Characterization of the unfolding of a weak focus and modulus of analytic classification

Arriagada Silva, Waldo G. 06 1900 (has links)
La thèse présente une description géométrique d’un germe de famille générique déployant un champ de vecteurs réel analytique avec un foyer faible à l’origine et son complexifié : le feuilletage holomorphe singulier associé. On montre que deux germes de telles familles sont orbitalement analytiquement équivalents si et seulement si les germes de familles de difféomorphismes déployant la complexification de leurs fonctions de retour de Poincaré sont conjuguées par une conjugaison analytique réelle. Le “caractère réel” de la famille correspond à sa Z2-équivariance dans R^4, et cela s’exprime comme l’invariance du plan réel sous le flot du système laquelle, à son tour, entraîne que l’expansion asymptotique de la fonction de Poincaré est réelle quand le paramètre est réel. Le pullback du plan réel après éclatement par la projection monoidal standard intersecte le feuilletage en une bande de Möbius réelle. La technique d’éclatement des singularités permet aussi de donner une réponse à la question de la “réalisation” d’un germe de famille déployant un germe de difféomorphisme avec un point fixe de multiplicateur égal à −1 et de codimension un comme application de semi-monodromie d’une famille générique déployant un foyer faible d’ordre un. Afin d’étudier l’espace des orbites de l’application de Poincaré, nous utilisons le point de vue de Glutsyuk, puisque la dynamique est linéarisable auprès des points singuliers : pour les valeurs réels du paramètre, notre démarche, classique, utilise une méthode géométrique, soit un changement de coordonée (coordonée “déroulante”) dans lequel la dynamique devient beaucoup plus simple. Mais le prix à payer est que la géométrie locale du plan complexe ambiante devient une surface de Riemann, sur laquelle deux notions de translation sont définies. Après avoir pris le quotient par le relèvement de la dynamique nous obtenons l’espace des orbites, ce qui s’avère être l’union de trois tores complexes plus les points singuliers (l’espace résultant est non-Hausdorff). Les translations, le caractère réel de l’application de Poincaré et le fait que cette application est un carré relient les différentes composantes du “module de Glutsyuk”. Cette propriété implique donc le fait qu’une seule composante de l’invariant Glutsyuk est indépendante. / The thesis gives a geometric description for the germ of the singular holomorphic foliation associated with the complexification of a germ of generic analytic family unfolding a real analytic vector field with a weak focus at the origin. We show that two such germs of families are orbitally analytically equivalent if and only if the germs of families of diffeomorphisms unfolding the complexified Poincaré map of the singularities are conjugate by a real analytic conjugacy. The Z2-equivariance of the family of real vector fields in R^4 is called the “real character” of the system. It is expressed by the invariance of the real plane under the flow of the system which, in turn, carries the real asymptotic expansion of the Poincaré map when the parameter is real. After blowing up the singularity, the pullback of the real plane by the standard monoidal map intersects the foliation in a real Möbius strip. The blow up technique allows to “realize” a germ of generic family unfolding a germ of diffeomorphism of codimension one and multiplier −1 at the origin as the semi-monodromy of a generic family unfolding an order one weak focus. In order to study the orbit space of the Poincaré map, we perform a trade-off between geometry and dynamics under the Glutsyuk point of view (where the dynamics is linearizable near the singular points): in the resulting “unwrapping coordinate” the dynamics becomes much simpler, but the price we pay is that the local geometry of the ambient complex plane turns into a much more involved Riemann surface. Over the latter, two notions of translations are defined. After taking the quotient by the lifted dynamics we get the orbit space, which turns out to be the union of three complex tori and the singular points (this space is non- Hausdorff). The Glutsyuk invariant is then defined over annular-like regions on the tori. The translations, the real character and the fact that the Poincaré map is the square of the semi-monodromy map, relate the different components of the Glutsyuk modulus. That property yields only one independent component of the Glutsyuk invariant.
28

On the Conjugacy of Maximal Toral Subalgebras of Certain Infinite-Dimensional Lie Algebras

Gontcharov, Aleksandr 10 September 2013 (has links)
We will extend the conjugacy problem of maximal toral subalgebras for Lie algebras of the form $\g{g} \otimes_k R$ by considering $R=k[t,t^{-1}]$ and $R=k[t,t^{-1},(t-1)^{-1}]$, where $k$ is an algebraically closed field of characteristic zero and $\g{g}$ is a direct limit Lie algebra. In the process, we study properties of infinite matrices with entries in a B\'zout domain and we also look at how our conjugacy results extend to universal central extensions of the suitable direct limit Lie algebras.
29

Existência da função de Lyapunov

Prado, Eder Flávio [UNESP] 19 February 2010 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:26:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-19Bitstream added on 2014-06-13T18:47:53Z : No. of bitstreams: 1 prado_ef_me_sjrp.pdf: 346611 bytes, checksum: 28c34647c269c1cbaea17d3787faa4cf (MD5) / Neste trabalho vamos estudar equações diferenciais ordinárias e analisar seu comportamento ao longo de suas trajetórias, com o principal objetivo de encontar, caso possível, uma função de Lyapunov apropriada para o sistema, isto é, dar condição suficiente e necessária para a existência dessa função. / In this work we study ordinary differential equations and analyse the behavior along of trajectories. The main goal is to find Lyapunov functions for the system when possibel: i e, we want to find necessary and sufficient conditions for the existence of those.
30

Triple generations of the Lyons sporadic simple group

Motalane, Malebogo John 03 1900 (has links)
The Lyons group denoted by Ly is a Sporadic Simple Group of order 51765179004000000 = 28 37 56 7 11 31 37 67. It(Ly) has a trivial Schur Multiplier and a trivial Outer Automorphism Group. Its maximal subgroups are G2(5) of order 5859000000 and index 8835156, 3 McL:2 of order 5388768000 and index 9606125, 53 L3(5) of order 46500000 and index 1113229656, 2 A11 of order 29916800 and index 1296826875, 51+4 + :4S6 of order 9000000 and index 5751686556, 35:(2 M11) of order 3849120 and index 13448575000, 32+4:2 A5 D8 of order 699840 and index 73967162500, 67:22 of order 1474 and index 35118846000000 and 37:18 of order 666 and index 77725494000000. Its existence was suggested by Richard Lyons. Lyons characterized its order as the unique possible order of any nite simple group where the centralizer of some involution is isomorphic to the nontrivial central extension of the alternating group of degree 11 by the cyclic group of order 2. Sims proved the existence of this group and its uniqueness using permutations and machine calculations. In this dissertation, we compute the (p; q; t)-generations of the Lyons group for dis- tinct primes p, q and t which divide the order of Ly such that p < q < t. For computations, we made use of the Computer Algebra System GAP / Mathematical Sciences / M.Sc. (Mathematics)

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