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Search Results: 1 - 10 of 143337 matches for " Haroldo V. Ribeiro "
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Complexity-Entropy Causality Plane as a Complexity Measure for Two-Dimensional Patterns
Haroldo V. Ribeiro, Luciano Zunino, Ervin K. Lenzi, Perseu A. Santoro, Renio S. Mendes
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0040689
Abstract: Complexity measures are essential to understand complex systems and there are numerous definitions to analyze one-dimensional data. However, extensions of these approaches to two or higher-dimensional data, such as images, are much less common. Here, we reduce this gap by applying the ideas of the permutation entropy combined with a relative entropic index. We build up a numerical procedure that can be easily implemented to evaluate the complexity of two or higher-dimensional patterns. We work out this method in different scenarios where numerical experiments and empirical data were taken into account. Specifically, we have applied the method to fractal landscapes generated numerically where we compare our measures with the Hurst exponent; liquid crystal textures where nematic-isotropic-nematic phase transitions were properly identified; 12 characteristic textures of liquid crystals where the different values show that the method can distinguish different phases; and Ising surfaces where our method identified the critical temperature and also proved to be stable.
Distance to the Scaling Law: A Useful Approach for Unveiling Relationships between Crime and Urban Metrics
Luiz G. A. Alves, Haroldo V. Ribeiro, Ervin K. Lenzi, Renio S. Mendes
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0069580
Abstract: We report on a quantitative analysis of relationships between the number of homicides, population size and ten other urban metrics. By using data from Brazilian cities, we show that well-defined average scaling laws with the population size emerge when investigating the relations between population and number of homicides as well as population and urban metrics. We also show that the fluctuations around the scaling laws are log-normally distributed, which enabled us to model these scaling laws by a stochastic-like equation driven by a multiplicative and log-normally distributed noise. Because of the scaling laws, we argue that it is better to employ logarithms in order to describe the number of homicides in function of the urban metrics via regression analysis. In addition to the regression analysis, we propose an approach to correlate crime and urban metrics via the evaluation of the distance between the actual value of the number of homicides (as well as the value of the urban metrics) and the value that is expected by the scaling law with the population size. This approach has proved to be robust and useful for unveiling relationships/behaviors that were not properly carried out by the regression analysis, such as the non-explanatory potential of the elderly population when the number of homicides is much above or much below the scaling law, the fact that unemployment has explanatory potential only when the number of homicides is considerably larger than the expected by the power law, and a gender difference in number of homicides, where cities with female population below the scaling law are characterized by a number of homicides above the power law.
Empirical analysis on the connection between power-law distributions and allometries for urban indicators
Luiz G. A. Alves,Haroldo V. Ribeiro,Ervin K. Lenzi,Renio S. Mendes
Physics , 2014, DOI: 10.1016/j.physa.2014.04.046
Abstract: We report on the existing connection between power-law distributions and allometries. As it was first reported in [PLoS ONE 7, e40393 (2012)] for the relationship between homicides and population, when these urban indicators present asymptotic power-law distributions, they can also display specific allometries among themselves. Here, we present an extensive characterization of this connection when considering all possible pairs of relationships from twelve urban indicators of Brazilian cities (such as child labor, illiteracy, income, sanitation and unemployment). Our analysis reveals that all our urban indicators are asymptotically distributed as power laws and that the proposed connection also holds for our data when the allometric relationship displays enough correlations. We have also found that not all allometric relationships are independent and that they can be understood as a consequence of the allometric relationship between the urban indicator and the population size. We further show that the residuals fluctuations surrounding the allometries are characterized by an almost constant variance and log-normal distributions.
Scale-adjusted metrics for predicting the evolution of urban indicators and quantifying the performance of cities
Luiz G. A. Alves,Renio S. Mendes,Ervin K. Lenzi,Haroldo V. Ribeiro
Physics , 2015, DOI: 10.1371/journal.pone.0134862
Abstract: More than a half of world population is now living in cities and this number is expected to be two-thirds by 2050. Fostered by the relevancy of a scientific characterization of cities and for the availability of an unprecedented amount of data, academics have recently immersed in this topic and one of the most striking and universal finding was the discovery of robust allometric scaling laws between several urban indicators and the population size. Despite that, most governmental reports and several academic works still ignore these nonlinearities by often analyzing the raw or the per capita value of urban indicators, a practice that actually makes the urban metrics biased towards small or large cities depending on whether we have super or sublinear allometries. By following the ideas of Bettencourt et al., we account for this bias by evaluating the difference between the actual value of an urban indicator and the value expected by the allometry with the population size. We show that this scale-adjusted metric provides a more appropriate/informative summary of the evolution of urban indicators and reveals patterns that do not appear in the evolution of per capita values of indicators obtained from Brazilian cities. We also show that these scale-adjusted metrics are strongly correlated with their past values by a linear correspondence and that they also display crosscorrelations among themselves. Simple linear models account for 31%-97% of the observed variance in data and correctly reproduce the average of the scale-adjusted metric when grouping the cities in above and below the allometric laws. We further employ these models to forecast future values of urban indicators and, by visualizing the predicted changes, we verify the emergence of spatial clusters characterized by regions of the Brazilian territory where we expect an increase or a decrease in the values of urban indicators.
Move-by-Move Dynamics of the Advantage in Chess Matches Reveals Population-Level Learning of the Game
Haroldo V. Ribeiro, Renio S. Mendes, Ervin K. Lenzi, Marcelo del Castillo-Mussot, Luís A. N. Amaral
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0054165
Abstract: The complexity of chess matches has attracted broad interest since its invention. This complexity and the availability of large number of recorded matches make chess an ideal model systems for the study of population-level learning of a complex system. We systematically investigate the move-by-move dynamics of the white player’s advantage from over seventy thousand high level chess matches spanning over 150 years. We find that the average advantage of the white player is positive and that it has been increasing over time. Currently, the average advantage of the white player is 0.17 pawns but it is exponentially approaching a value of 0.23 pawns with a characteristic time scale of 67 years. We also study the diffusion of the move dependence of the white player’s advantage and find that it is non-Gaussian, has long-ranged anti-correlations and that after an initial period with no diffusion it becomes super-diffusive. We find that the duration of the non-diffusive period, corresponding to the opening stage of a match, is increasing in length and exponentially approaching a value of 15.6 moves with a characteristic time scale of 130 years. We interpret these two trends as a resulting from learning of the features of the game. Additionally, we find that the exponent characterizing the super-diffusive regime is increasing toward a value of 1.9, close to the ballistic regime. We suggest that this trend is due to the increased broadening of the range of abilities of chess players participating in major tournaments.
Solutions for a q-generalized Schr?dinger equation of entangled interacting particles
Luiz G. A. Alves,Haroldo V. Ribeiro,Maike A. F. Santos,Renio S. Mendes,Ervin K. Lenzi
Physics , 2015, DOI: 10.1016/j.physa.2015.02.063
Abstract: We report on the time dependent solutions of the $q-$generalized Schr\"odinger equation proposed by Nobre et al. [Phys. Rev. Lett. 106, 140601 (2011)]. Here we investigate the case of two free particles and also the case where two particles were subjected to a Moshinsky-like potential with time dependent coefficients. We work out analytical and numerical solutions for different values of the parameter $q$ and also show that the usual Schr\"odinger equation is recovered in the limit of $q\rightarrow 1$. An intriguing behavior was observed for $q=2$, where the wave function displays a ring-like shape, indicating a bind behavior of the particles. Differently from the results previously reported for the case of one particle, frozen states appear only for special combinations of the wave function parameters in case of $q=3$.
Dimensionamento de motores para o bombeamento de água
Oliveira Filho, Delly;Ribeiro, Marcos C.;Mantovani, Everardo C.;Soares, Ant?nio A.;Fernandes, Haroldo C.;
Engenharia Agrícola , 2010, DOI: 10.1590/S0100-69162010000600003
Abstract: sizing motors with power above the required implies in higher initial cost, lower performance and lower power factor. since 1996, that electrical motor is built in brazil with service factors greater than the unity, obeying the standard values. the service factor informs the motor's available power in continuous regime under nominal condition. the technical literature for sizing motors to operate hydraulic pumps indicates the need of adoption of sizing factors in the motor's power. both the service factor and the sizing factor are security factors to size motors. these safety factors have the function to supply greater power demand due to changes in the working conditions such as, pump or motor characteristic curves, or energy quality like voltage imbalance or oscillation. the conclusion is that there is no need to use sizing factor for rating motors to drive hydraulic pump, because oversize may lead in performance decrease and greater initial costs. the size that considers both the security factors implies in an over sizing from 15% to 88%.
Avalia o de variáveis restritivas à qualidade na execu o do programa nacional de alimenta o escolar com inser o à gest o estratégica de recursos públicos.
José Moreira da Silva Neto,Ricardo Plácido Ribeiro,Haroldo Cristovam Teixeira Leite
Revista Eletr?nica de Ciência Administrativa - RECADM , 2010, DOI: 10.5329/369
Scaling laws in the dynamics of crime growth rate
Luiz Gustavo de Andrade Alves,Haroldo Valentin Ribeiro,Renio dos Santos Mendes
Physics , 2013, DOI: 10.1016/j.physa.2013.02.002
Abstract: The increasing number of crimes in areas with large concentrations of people have made cities one of the main sources of violence. Understanding characteristics of how crime rate expands and its relations with the cities size goes beyond an academic question, being a central issue for contemporary society. Here, we characterize and analyze quantitative aspects of murders in the period from 1980 to 2009 in Brazilian cities. We find that the distribution of the annual, biannual and triannual logarithmic homicide growth rates exhibit the same functional form for distinct scales, that is, a scale invariant behavior. We also identify asymptotic power-law decay relations between the standard deviations of these three growth rates and the initial size. Further, we discuss similarities with complex organizations.
Learning Rate Updating Methods Applied to Adaptive Fuzzy Equalizers for Broadband Power Line Communications
Moisés V. Ribeiro
EURASIP Journal on Advances in Signal Processing , 2004, DOI: 10.1155/s1687617204407021
Abstract: This paper introduces adaptive fuzzy equalizers with variable step size for broadband power line (PL) communications. Based on delta-bar-delta and local Lipschitz estimation updating rules, feedforward, and decision feedback approaches, we propose singleton and nonsingleton fuzzy equalizers with variable step size to cope with the intersymbol interference (ISI) effects of PL channels and the hardness of the impulse noises generated by appliances and nonlinear loads connected to low-voltage power grids. The computed results show that the convergence rates of the proposed equalizers are higher than the ones attained by the traditional adaptive fuzzy equalizers introduced by J. M. Mendel and his students. Additionally, some interesting BER curves reveal that the proposed techniques are efficient for mitigating the above-mentioned impairments.
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