Navegando por Autor "SOUZA, Raimundo Nonato Carneiro de"

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Acesso aberto (Open Access)
Avalanche como rede de percolação não homogênea
(Universidade Federal do Pará, 2019-09-13) SOUZA, Raimundo Nonato Carneiro de; TAVARES, Heliton Ribeiro; http://lattes.cnpq.br/1313373547379006; MESQUITA, André Luiz Amarante; http://lattes.cnpq.br/1331279630816662
Avalanches can be considered as a percolation process. This hypothesis will be posted to evaluate if this approach is possible and what are its advantages. Some literature speculates that there is the possibility of considering avalanches as a percolation event. However, there is no clear distinction from the percolation model that these events describe, either a homogeneous or non-homogeneous process. This work deals with avalanche simulations as physical cases of percolation. To characterize the avalanches, two percolation models were simulated: homogeneous and heterogeneous. Simulations were developed to compare avalanches in both models. To perform these simulations, the probability of a site being open equal to 0:5 was used. The sizes and transients were measured for each avalanche in the different models. To close the work, experiments were carried out to create avalanches, in order to better calibrate the simulations using real avalanche data. For when comparing the simulated results with existing data in the literature, a typical behavior of a probability function was perceived. Given this behavior one can make predictions about the size of the avalanches. Analyzing the results obtained, it is possible that the behavior of avalanches created with non-homogeneous probability presented well defined characteristics, having larger values of size and transient. It was concluded that the non-homogeneous model has a high stability and is better in the evolution aspect of the avalanche, so with some adjustments the heterogeneous model can approach a real avalanche with greater accuracy.
Acesso aberto (Open Access)
Densidade crítica no modelo de percolação em rede de Bethe não-homogênea
(Sociedade Brasileira de Matemática Aplicada e Computacional, 2015-08) TAVARES, Héliton Ribeiro; SOUZA, Raimundo Nonato Carneiro de; TAVARES, Maria Regina Madruga; FARIAS, Valcir Joao da Cunha
In this work we deal with an inhomogeneous Bethe lattice percolation model where the probability of an edge in level n is open changes according as n. This model can be appropriate to the case where the media changes its density in a systematic way, such as the proliferation of insects that depends on the temperature and humidity, which fluctuates between day and night. We consider the case where the density p(·) follows a function of the distance l(.) from the origin, given by a sinusoid function p(·) = p + (1 - p)|sin(l(.))|. For this model we present results of Monte-Carlo simulation showing the behavior of the probability of percolation with a second-order phase transition, but we present too a formal proof that the density is non trivial, with the mathematical expression to compute the percolation threshold.