Attractor
Mostrando 13-24 de 61 artigos, teses e dissertações.
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13. A multiparameter chaos control method applied to maps
Chaos is a kind of nonlinear system response that has a dense set of unstable periodic orbits (UPOs) embedded in a chaotic attractor. The idea of the chaos control is to explore the UPO stabilization obtaining dynamical systems that may quickly react to some new situation, changing conditions and their response. The OGY (Ott-Grebogi-Yorke) method achieves sy
Brazilian Journal of Physics. Publicado em: 2008-12
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14. A discrete inhomogeneous model for the yeast cell cycle
We study the robustness and stability of the yeast cell regulatory network by using a general inhomogeneous discrete model. We find that inhomogeneity, on average, enhances the stability of the biggest attractor of the dynamics and that the large size of the basin of attraction is robust against changes in the parameters of inhomogeneity. We find that the mo
Brazilian Journal of Physics. Publicado em: 2008-09
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15. Discrete dynamical systems: stability, asymptotic behavior and synchronization / Sistemas dinâmicos discretos: estabilidade, comportamento assintótico e sincronização
Este trabalho é em parte baseado no livro The Stability and Control of Discrete Processes de Joseph P. LaSalle. Nós estudamos equações como x(n+1) = T(x(n)), onde T : R POT. mSETAR POT. mé uma aplicação contínua, com o sistema dinâmico associado PI(n,x) := T POT. n(x). Nós fornecemos condições suficientes para a estabilidade de equilíbrios usand
Publicado em: 2008
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16. Deterministic partially self-avoiding walks: analytical results for the effect of tourists memory in the exploration of disordered media / Caminhadas deterministas parcialmente auto-repulsivas: resultados analíticos para o efeito da memória do turista na exploração de meios desordenados
Considere um meio desordenado constituído por $N$ pontos cujas coordenadas são geradas aleatoriamente de maneira uniforme e independente nas arestas unitárias de um hipercubo $d$-dimensional. As probabilidades de vizinhança entre os pares de pontos deste meio são expressas através da fórmula de Cox. Um caminhante parte de um dado ponto deste meio deso
Publicado em: 2008
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17. Born-Infeld corrections to the entropy function of heterotic black holes
We use the black hole entropy function to study the effect of Born-Infeld terms on the entropy of extremal black holes in heterotic string theory in four dimensions. We find that after adding a set of higher curvature terms to the effective action, attractor mechanism works and Born-Infeld terms contribute to the stretching of near horizon geometry. In the a
Brazilian Journal of Physics. Publicado em: 2007-06
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18. Global injectivity for applications between euclidean spaces / Injetividade global para aplicações entre espaços euclideanos
We present some results which give suficient conditions for a local diffeomorphism from the n-dimensional Euclidean space into itself be globally injective. Within this context, we consider some partial results addressed to solve the well known Fixed Point Conjecture and Jacobian Conjecture. From the dynamical point of view, there are connections between glo
Publicado em: 2007
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19. Topological studies of periodic orbits in the experimental Chua s circuit / Estudo topológico de órbitas periódicas no circuito experimental de Chua
We have studied the dynamical behavior of experimental time series obtained from a Chua s circuit by variation of two parameter control, $Delta R_1$ and $Delta R_2$. We investigated the chaotic and periodic behaviors of the circuit, analyzing temporal series around and inside of two periodic windows in the two-parameter space $(Delta R_1,Delta R_2)$. In the
Publicado em: 2006
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20. Baixa dimensionalidade numa rede de neurÃnios de FitzHugh-Nagumo
A atividade de um conjunto de neurÃnios interligados à um problema de atual interesse que pode ser abordado com uma descriÃÃo detalhada dos neurÃnios da populaÃÃo ou, estudando a dinÃmica da resposta dessas populaÃÃes sim descrever em detalhe o comportamento individual dos neurÃnios. O modelo de Wilson-Cowan consiste em equaÃÃes para as taxas de
Publicado em: 2006
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21. Attractors in dark energy models with Born-Infeld scalar field
We derive, in the large scale limit, analytical solutions for a dark energy model described by the Born-Infeld field plus a perfect fluid, both for homogeneous background and first order perturbations. These analytical results are compared with numerical solutions in a model with radiation, pressureless matter and the field. We investigate the non-adiabatic
Brazilian Journal of Physics. Publicado em: 2005-12
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22. Simulating a chaotic process
Computer simulations of partial differential equations of mathematical physics typically lead to some kind of high-dimensional dynamical system. When there is chaotic behavior we are faced with fundamental dynamical difficulties. We choose as a paradigm of such high-dimensional system a kicked double rotor. This system is investigated for parameter values at
Brazilian Journal of Physics. Publicado em: 2005-03
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23. The communication process development of the mathematics meanings in the classroom / O desenvolvimento do processo de comunicação dos significados matemáticos em sala de aula
Starting from the principle that each of us possess a place from where to draw our perspectives on a subject, this work analyses the discursive exchanges between a dynamic system, constituted of the relationship professor-student, in which weve considered the multiple aspects or elements that exercise power over one another along the irreversible time in thi
Publicado em: 2005
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24. "Comportamento assintótico de problemas parabólicos em domínios tipo Dumbbell" / Assimptotic Behavior for parabolic problems in Dumbbell domains
The aim of this work is to study the asymptotic dynamics of parabolic problems in dumbbell type domains. To that end firstly, we study upper semicontinuity of attractors for parabolic problems with homogeneous Neumann boundary conditions and afterwards we study the existence of stable nonconstant equilibria for reaction-diffusion problems with nonlinear Neum
Publicado em: 2004