Programa de Modelagem Computacional

Salvador, Brazil

Programa de Modelagem Computacional

Salvador, Brazil

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Henrique T.,State University of Feira de Santana | Fadigas I.S.,State University of Feira de Santana | Rosa M.G.,State University of Feira de Santana | Pereira H.B.B.,Programa de Modelagem Computacional | Pereira H.B.B.,Bahia State University
Social Network Analysis and Mining | Year: 2014

Continuous technological advances have resulted in analysis techniques that can be used in network theory. Topological characterisation, study of cohesion, and analysis of prominence are relevant techniques through which vertices (e.g., words) and their relationships are considered. The goal of this paper is to produce a comparative study on semantic networks based on titles of scientific papers in the field of mathematics education in Portuguese (Brazil) and English to ascertain the topological structure of these semantic networks and to present reflections thereafter concerning the diffusion of mathematics education. The vertices of proposed semantic networks are words with intrinsic meaning belonging to the titles of scientific papers and two words are connected if both belong to the same title. Methods and metrics from social and complex network analysis have been used to develop a diagnosis of the characterisation of this type of semantic network. Within this context, this study could be used to offer support to facilitate the process of diffusing knowledge in specific areas. © 2014, Springer-Verlag Wien.


Fadigas I.S.,State University of Feira de Santana | Pereira H.B.B.,Programa de Modelagem Computacional | Pereira H.B.B.,Bahia State University
Physica A: Statistical Mechanics and its Applications | Year: 2013

The characterization of complex networks is a procedure that is currently found in several research studies. Nevertheless, few studies present a discussion on networks in which the basic element is a clique. In this paper, we propose an approach based on a network of cliques. This approach consists not only of a set of new indices to capture the properties of a network of cliques but also of a method to characterize complex networks of cliques (i.e., some of the parameters are proposed to characterize the small-world phenomenon in networks of cliques). The results obtained are consistent with results from classical methods used to characterize complex networks. © 2013 Elsevier B.V. All rights reserved.


Pereira H.B.d.B.,Programa de Modelagem Computacional | Pereira H.B.d.B.,State University of Feira de Santana | Zebende G.F.,Programa de Modelagem Computacional | Zebende G.F.,State University of Feira de Santana | And 2 more authors.
Computers and Education | Year: 2010

It is common to start a course on computer programming logic by teaching the algorithm concept from the point of view of natural languages, but in a schematic way. In this sense we note that the students have difficulties in understanding and implementation of the problems proposed by the teacher. The main idea of this paper is to show that the logical reasoning of computer programming students can be efficiently developed by using at the same time Turing Machine, cellular automata (Wolfram rule) and fractals theory via Problem-Based Learning (PBL). The results indicate that this approach is useful, but the teacher needs introducing, in an interdisciplinary context, the simple theory of cellular automata and the fractals before the problem implementation. © 2010 Elsevier Ltd. All rights reserved.


Pereira H.B.B.,Programa de Modelagem Computacional | Pereira H.B.B.,State University of Feira de Santana | Fadigas I.S.,State University of Feira de Santana | Senna V.,Programa de Modelagem Computacional | And 2 more authors.
Physica A: Statistical Mechanics and its Applications | Year: 2011

In this paper we study the topological structure of semantic networks based on titles of papers published in scientific journals. It discusses its properties and presents some reflections on how the use of social and complex network models can contribute to the diffusion of knowledge. The proposed method presented here is applied to scientific journals where the titles of papers are in English or in Portuguese. We show that the topology of studied semantic networks are small-world and scale-free. © 2010 Elsevier B.V. All rights reserved.


Rosa Jr. A.C.P.,Programa de Modelagem Computacional | De Jesus J.C.O.,UEFS | Moret M.A.,Programa de Modelagem Computacional
Physica A: Statistical Mechanics and its Applications | Year: 2013

We study the X-ray intensities of 142 light curves of cataclysmic variables, galaxies, pulsars, supernova remnants and other X-ray sources present in the public data collected by the instrument All Sky Monitor on board the satellite Rossi X-ray Timing Explorer. We show that the X-ray light curves coming from astrophysical systems obey Tsallis's q-Gaussian distribution as probability density. This fact strongly suggests that these astrophysical systems behave in a non-extensive manner. Furthermore, the q entropic indices for these systems were obtained and they provide an indication of the nonextensivity degree of each of these astrophysical systems. The q-value increases for systems if the Tsallis entropy decreases. © 2013 Elsevier B.V. All rights reserved.


Fox A.J.,European Southern Observatory | Fox A.J.,University of Cambridge | Ledoux C.,European Southern Observatory | Petitjean P.,CNRS Paris Institute of Astrophysics | And 2 more authors.
Astronomy and Astrophysics | Year: 2011

We present VLT/UVES spectroscopy of the quasar Q0841+129, whose spectrum shows a proximate damped Ly-α (PDLA) absorber at z = 2.47621 and a proximate sub-DLA at z = 2.50620, both lying close in redshift to the QSO itself at zem = 2.49510 ± 0.00003. This fortuitous arrangement, with the sub-DLA acting as a filter that hardens the QSO's ionizing radiation field, allows us to model the ionization level in the foreground PDLA, and provides an interesting case-study on the origin of the high-ion absorption lines Si iv, C iv, and O vi in DLAs. The high ions in the PDLA show at least five components spanning a total velocity extent of 160 km s-1, whereas the low ions exist predominantly in a single component spanning just 30 km s-1. We examine various models for the origin of the high ions. Both photoionization and turbulent mixing layer models are fairly successful at reproducing the observed ionic ratios after correcting for the non-solar relative abundance pattern, though neither model can explain all five components. We show that the turbulent mixing layer model, in which the high ions trace the interfaces between the cool PDLA gas and a hotter phase of shock-heated plasma, can explain the average high-ion ratios measured in a larger sample of 12 DLAs. © 2011 ESO.


Moret M.A.,Programa de Modelagem Computacional | Pereira H.B.B.,Programa de Modelagem Computacional | Monteiro S.L.,Laboratorio Nacional Of Computacao Cientfica | Galeao A.C.,Laboratorio Nacional Of Computacao Cientfica
Physica A: Statistical Mechanics and its Applications | Year: 2012

Evolution of species is a complex phenomenon. Some theoretical models take into account evolution of species, like the BakSneppen model that obtain punctuated equilibrium from self-organized criticality and the Penna model for biological aging that consists in a bit-string model subjected to aging, reproduction and death. In this work we propose a simple model to study different scenarios used to simulate the evolution of species. This model is based on Darwin's ideas of evolution. The present findings show that punctuated equilibria and stasis seem to be obtained directly from the mutation, selection of parents and the genetic crossover, and are very close to the fossil data analysis. © 2011 Elsevier B.V. All rights reserved.


Moret M.A.,Programa de Modelagem Computacional | Antonio L.Q.,Programa de Modelagem Computacional | Pereira H.B.B.,Programa de Modelagem Computacional
Physica A: Statistical Mechanics and its Applications | Year: 2012

Transportation problems are important complex systems because of the increased number of vehicles in cities. In this paper, we study time series of vehicle demand by using the ferry-boat system between Salvador city and Itaparica island, in Bahia, Brazil. We compare the traditional demand analysis (ARIMA method) with the self-affine ones (the scaling exponent α and the density of crossing points ρ). In addition, taking into account the inherent self-affine behavior we study the stationary states of this dynamic process by using a nonlinear FokkerPlanck equation. The present findings indicate that the scaling exponent α describes some properties of flux of vehicles using the ferry-boat system. The behavior of α gives an alternative explanation about demand analysis, and the nonlinear FokkerPlanck equation presents a solution close to the stationary behavior of this complex dynamical analysis. © 2011 Elsevier B.V. All rights reserved.


Moret M.A.,Programa de Modelagem Computacional
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2014

In this paper we study the time series of sunspots by using two different approaches, analyzing its self-affine behavior and studying its distribution. The long-range correlation exponent α has been calculated via Detrended Fluctuation Analysis and the power law vanishes to values greater than 11 years. On the other hand, the distribution of the sunspots obeys a q-exponential decay that suggests a non-extensive behavior. This observed characteristic seems to take an alternative interpretation of the sunspots dynamics. The present findings suggest us to propose a dynamic model of sunspots formation based on a nonlinear Fokker-Planck equation. Therefore its dynamic process follows the generalized thermostatistical formalism. © 2013 Elsevier B.V.


Moret M.A.,Programa de Modelagem Computacional
Physica A: Statistical Mechanics and its Applications | Year: 2011

The major factor that drives a protein toward collapse and folding is the hydrophobic effect. At the folding process a hydrophobic core is shielded by the solvent-accessible surface area of the protein. We study the fractal behavior of 5526 protein structures present in the Brookhaven Protein Data Bank. Power laws of protein mass, volume and solvent-accessible surface area are measured independently. The present findings indicate that self-organized criticality is an alternative explanation for the protein folding. Also we note that the protein packing is an independent and constant value because the self-similar behavior of the volumes and protein masses have the same fractal dimension. This power law guarantees that a protein is a complex system. From the analyzed data, q-Gaussian distributions seem to fit well this class of systems. © 2011 Elsevier B.V. All rights reserved.

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