6 resultados para self-organized critical

em Universidade Federal do Rio Grande do Norte(UFRN)


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In this work, the study of some complex systems is done with use of two distinct procedures. In the first part, we have studied the usage of Wavelet transform on analysis and characterization of (multi)fractal time series. We have test the reliability of Wavelet Transform Modulus Maxima method (WTMM) in respect to the multifractal formalism, trough the calculation of the singularity spectrum of time series whose fractality is well known a priori. Next, we have use the Wavelet Transform Modulus Maxima method to study the fractality of lungs crackles sounds, a biological time series. Since the crackles sounds are due to the opening of a pulmonary airway bronchi, bronchioles and alveoli which was initially closed, we can get information on the phenomenon of the airway opening cascade of the whole lung. Once this phenomenon is associated with the pulmonar tree architecture, which displays fractal geometry, the analysis and fractal characterization of this noise may provide us with important parameters for comparison between healthy lungs and those affected by disorders that affect the geometry of the tree lung, such as the obstructive and parenchymal degenerative diseases, which occurs, for example, in pulmonary emphysema. In the second part, we study a site percolation model for square lattices, where the percolating cluster grows governed by a control rule, corresponding to a method of automatic search. In this model of percolation, which have characteristics of self-organized criticality, the method does not use the automated search on Leaths algorithm. It uses the following control rule: pt+1 = pt + k(Rc − Rt), where p is the probability of percolation, k is a kinetic parameter where 0 < k < 1 and R is the fraction of percolating finite square lattices with side L, LxL. This rule provides a time series corresponding to the dynamical evolution of the system, in particular the likelihood of percolation p. We proceed an analysis of scaling of the signal obtained in this way. The model used here enables the study of the automatic search method used for site percolation in square lattices, evaluating the dynamics of their parameters when the system goes to the critical point. It shows that the scaling of , the time elapsed until the system reaches the critical point, and tcor, the time required for the system loses its correlations, are both inversely proportional to k, the kinetic parameter of the control rule. We verify yet that the system has two different time scales after: one in which the system shows noise of type 1 f , indicating to be strongly correlated. Another in which it shows white noise, indicating that the correlation is lost. For large intervals of time the dynamics of the system shows ergodicity

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Recent studies have shown evidence of log-periodic behavior in non-hierarchical systems. An interesting fact is the emergence of such properties on rupture and breakdown of complex materials and financial failures. These may be examples of systems with self-organized criticality (SOC). In this work we study the detection of discrete scale invariance or log-periodicity. Theoretically showing the effectiveness of methods based on the Fourier Transform of the log-periodicity detection not only with prior knowledge of the critical point before this point as well. Specifically, we studied the Brazilian financial market with the objective of detecting discrete scale invariance in Bovespa (Bolsa de Valores de S˜ao Paulo) index. Some historical series were selected periods in 1999, 2001 and 2008. We report evidence for the detection of possible log-periodicity before breakage, shown its applicability to the study of systems with discrete scale invariance likely in the case of financial crashes, it shows an additional evidence of the possibility of forecasting breakage

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LEÃO, Adriano de Castro; DÓRIA NETO, Adrião Duarte; SOUSA, Maria Bernardete Cordeiro de. New developmental stages for common marmosets (Callithrix jacchus) using mass and age variables obtained by K-means algorithm and self-organizing maps (SOM). Computers in Biology and Medicine, v. 39, p. 853-859, 2009

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This thesis aims to enable a wider comprehension on thought operation as well as suggest alternatives for the formation of reflexive, critical, autonomous and creative individuals. The research defends the idea that it is possible for an individual to develop vigilant attention that makes thought flexibilization and change in the course of action, possible. This operation is called Internal Dialogue and is essentially characterized by a continuous openness towards novelty and learning. This makes it possible to minimize the usual way thought operates, in a automatic fashion (automatism). The research was based on theoretical references and ideas of David Bohm (1989;1994;2005) and Michael Polanyi (1983). The main emphasis was the understanding that a crisis situation enables awareness and state of alert that favors a more flexible thought pattern (Aragão Gomes, 1994, 1997). The methodology used was presentation and analysis of these moments through autobibliographical records with indication of crisis on behalf of the subjects. Other criteria were also used that enabled the composition of the analyzed material such as the fact that: the subjects were public and real, the data was available through accessible material; the subjects identified themselves as in crisis; these crisis were of varied kinds; they had different social, cultural and professional profiles. Thus, three auto-bibliographical elements were selected: the Infidel: the story of a woman that challenged Islam (2007), written by the political Muslim author Ayaan Hirsi; Still me: memories (2001), of the actor Christopher Reeve as well as Confessions of a Philosopher (2001), by the philosopher Bryan Magee. In these books an analysis was made related to parts that stated action an though operation that express internal dialogue. These were organized into categories that were pointed out as relevant for the identification of internal dialogue such as: Perceptions of physical reaction; emotions, beliefs and issues, individual actions, self judgment and thought, self questioning, comprehension, observation and empirical investigation, perception of the changes they performed in the world, escape of conditioning as well as action that resulted in new meaning. The analysis performed reinforces our goal once it sated that internal dialogue is an important tool that allows thought awareness, minimizing common automatism and making consciousness possible as well as favoring the occurrence of critical and reflexive thought. Thus, final considerations deal with the need for the development of teaching methodologies that address internal dialogue as a counterpoint to the many daily action that reinforce the automatism of thought

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This thesis aims to enable a wider comprehension on thought operation as well as suggest alternatives for the formation of reflexive, critical, autonomous and creative individuals. The research defends the idea that it is possible for an individual to develop vigilant attention that makes thought flexibilization and change in the course of action, possible. This operation is called Internal Dialogue and is essentially characterized by a continuous openness towards novelty and learning. This makes it possible to minimize the usual way thought operates, in a automatic fashion (automatism). The research was based on theoretical references and ideas of David Bohm (1989;1994;2005) and Michael Polanyi (1983). The main emphasis was the understanding that a crisis situation enables awareness and state of alert that favors a more flexible thought pattern (Aragão Gomes, 1994, 1997). The methodology used was presentation and analysis of these moments through autobibliographical records with indication of crisis on behalf of the subjects. Other criteria were also used that enabled the composition of the analyzed material such as the fact that: the subjects were public and real, the data was available through accessible material; the subjects identified themselves as in crisis; these crisis were of varied kinds; they had different social, cultural and professional profiles. Thus, three auto-bibliographical elements were selected: the Infidel: the story of a woman that challenged Islam (2007), written by the political Muslim author Ayaan Hirsi; Still me: memories (2001), of the actor Christopher Reeve as well as Confessions of a Philosopher (2001), by the philosopher Bryan Magee. In these books an analysis was made related to parts that stated action an though operation that express internal dialogue. These were organized into categories that were pointed out as relevant for the identification of internal dialogue such as: Perceptions of physical reaction; emotions, beliefs and issues, individual actions, self judgment and thought, self questioning, comprehension, observation and empirical investigation, perception of the changes they performed in the world, escape of conditioning as well as action that resulted in new meaning. The analysis performed reinforces our goal once it sated that internal dialogue is an important tool that allows thought awareness, minimizing common automatism and making consciousness possible as well as favoring the occurrence of critical and reflexive thought. Thus, final considerations deal with the need for the development of teaching methodologies that address internal dialogue as a counterpoint to the many daily action that reinforce the automatism of thought

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Resumo:

LEÃO, Adriano de Castro; DÓRIA NETO, Adrião Duarte; SOUSA, Maria Bernardete Cordeiro de. New developmental stages for common marmosets (Callithrix jacchus) using mass and age variables obtained by K-means algorithm and self-organizing maps (SOM). Computers in Biology and Medicine, v. 39, p. 853-859, 2009