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Rech P.C.,Santa Catarina State University
Neurocomputing | Year: 2011

In this paper we investigate numerically the parameter-space of an autonomous system of four nonlinear first-order ordinary differential equations, which represents a Hopfield neural network with four neurons. The study considers three independent two-dimensional cross-sections of the three-dimensional parameter-space generated by this mathematical model, every constructed considering Lyapunov exponent values. We show that is possible to completely characterize the dynamics of the system based in these three plots, which are representative of the three-dimensional parameter-space as a whole. © 2011 Elsevier B.V. Source


Rech P.C.,Santa Catarina State University
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2011

We report some two-dimensional parameter-space diagrams numerically obtained for the multi-parameter Hindmarsh-Rose neuron model. Several different parameter planes are considered, and we show that regardless of the combination of parameters, a typical scenario is preserved: for all choice of two parameters, the parameter-space presents a comb-shaped chaotic region immersed in a large periodic region. We also show that exist regions close these chaotic region, separated by the comb teeth, organized themselves in period-adding bifurcation cascades. © 2011 Elsevier B.V. All rights reserved. Source


da Silva F.C.,Santa Catarina State University
Health and quality of life outcomes | Year: 2014

The present study aimed to determine the effect of demographic characteristics, occupation, anthropometric indices, and leisure-time physical activity levels on coronary risk and health-related quality of life among military police officers from the State of Santa Catarina, Brazil. The sample included 165 military police officers who fulfilled the study's inclusion criteria. The International Physical Activity Questionnaire and the Short Form Health Survey were used, in addition to a spreadsheet of socio-demographic, occupational and anthropometric data. Statistical analyses were performed using descriptive analysis followed by Spearman Correlation and multiple linear regression analysis using the backward method. The waist-to-height ratio was identified as a risk factor low health-related quality of life. In addition, the conicity index, fat percentage, years of service in the military police, minutes of work per day and leisure-time physical activity levels were identified as risk factors for coronary disease among police officers. These findings suggest that the Military Police Department should adopt an institutional policy that allows police officers to practice regular physical activity in order to maintain and improve their physical fitness, health, job performance, and quality of life. Source


Rech P.C.,Santa Catarina State University
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2013

We investigate changes in periodicity, and even its suppression, by external periodic forcing in different two-dimensional maps, namely the Hénon map and the sine square map. By varying the amplitude of a periodic forcing with a fixed angular frequency, we show through numerical simulations in parameter-spaces that changes in periodicity may take place. We also show that windows of periodicity embedded in a chaotic region may be totally suppressed. © 2013 Elsevier B.V. Source


Batschauer A.L.,Santa Catarina State University | Mussa S.A.,Federal University of Santa Catarina | Heldwein M.L.,Federal University of Santa Catarina
IEEE Transactions on Industrial Electronics | Year: 2012

A novel three-phase hybrid multilevel converter is proposed for medium-voltage applications. The converter employs a conventional three-phase voltage source inverter (VSI) linking series connected half-bridge modules at each phase. With the proposed connection, a large portion of energy can be processed by the VSI by employing a single multi-pulse rectifier, while smaller power shares are processed within the half-bridge modules. Thus, the requirements for galvanically insulated dc sources are reduced. Modularity is naturally achieved. A modulation scheme for a four-level version is proposed and analyzed in detail. This scheme allows unidirectional power flow in all dc sources and, consequently, enables diode bridges to be employed in the rectification input stage for unidirectional applications. © 2011 IEEE. Source

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