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A control method and a system for controlling the piston of a resonant linear compressor including at least one electronic control unit, the electronic control unit including at least one observing electronic circuit and at least one control circuit associated to each other. The observing electronic circuit is configured for: measuring at least one electric magnitude of the electric motor; estimating at least one set of electric parameters and at least one set of mechanical parameters of the resonant linear compressor; and estimating and providing at least one control parameter of the system for the control circuit based on the measured electric magnitude measured and on the estimated set of electric and mechanical parameters. The control circuit is configured for actuating the electric motor from the at least one control parameter.

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.

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.

Vieira D.,Santa Catarina State University
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

Electrons in one dimension display the unusual property of separating their spin and charge into two independent entities: The first, which derives from uncharged spin-1/2 electrons, can travel at different velocities when compared with the second, which is built from charged spinless electrons. Predicted theoretically in the early 1960s, spin-charge separation has attracted renewed attention since the first evidences of experimental observation, with usual mentions as a possible explanation for high-temperature superconductivity. In one-dimensional (1D) model systems, spin-charge separation causes the frequencies of Friedel oscillations to suffer a 2k F→4k F crossover, mainly when dealing with strong correlations, where they are referred to as Wigner crystal oscillations. In nonmagnetized systems, the current density functionals that are applied to the 1D Hubbard model are not seen to reproduce this crossover, which leads to a more fundamental question: Are the Wigner crystal oscillations in 1D systems noninteracting V-representable? Or, is there a spin-independent Kohn-Sham potential that is able to yield spin-charge separation? Finding an appropriate answer to both questions is our main task here. By means of exact and density matrix renormalization group solutions, as well as an exchange-correlation potential introduced here, we show the answer to be positive. Specifically, the V-representable 4k F oscillations emerge from attractive interactions mediated by positively charged spinless holes-the holons-as an additional contribution to the repulsive on-site Hubbard interaction. © 2012 American Physical Society.

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.

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.

Filho J.M.C.,Santa Catarina State University
International Journal of Advanced Manufacturing Technology | Year: 2012

Mill turning is a process applied in the milling of a curved surface while the workpiece rotates around its center. Depending on the eccentricity of the tool, when a flat-end mill tool performs a curved trajectory perpendicular to the rotation axis of the tool, its bottom part is engaged in removing material. In order to optimize the process, the cutting force needs to be predicted. Hence, in this work, an approach to simulating the cutting force in mill turning is presented. The case of non-eccentricity of the tool is considered. The undeformed chip geometry is modeling as a function of the tool engagement considering the process kinematics. Experiments were conducted on a five-axis machining center enabling the measurement of the X-Y and Z components of the cutting forces. In order to verify the influence of the bottom part of the tool on the cutting forces, experiments were carried out using three different cutting depths. Numerical cutting simulations and experimental test results are compared to validate the proposed approach. © Springer-Verlag London Limited 2011.

Rech P.C.,Santa Catarina State University
Chinese Physics Letters | Year: 2012

Some two-dimensional parameter-space diagrams are numerically obtained by considering the largest Lyapunov exponent for a four-dimensional thirteen-parameter Hindmarsh - Rose neuron model. Several different parameter planes are considered, and it is shown that depending on the combination of parameters, a typical scenario can be preserved: for some choice of two parameters, the parameter plane presents a comb-shaped chaotic region embedded in a large periodic region. It is also shown that there exist regions close to these comb-shaped chaotic regions, separated by the comb teeth, organizing themselves in period-adding bifurcation cascades. © 2012 Chinese Physical Society and IOP Publishing Ltd.

Terry R.F.,World Health Organization | Salm J.F.,Santa Catarina State University | Nannei C.,World Health Organization | Dye C.,World Health Organization
Science | Year: 2014

A global map of health R&D activity would improve the coordination of research and help to match limited resources with public health priorities, such as combating antimicrobial resistance. The challenges of R&D mapping are large because there are few standards for research classification and governance and limited capacity to report on R&D data, especially in low-income countries. Nevertheless, based on developments in semantic classification, and with better reporting of funded research though the Internet, it is now becoming feasible to create a global observatory for health R&D.

Rech P.C.,Santa Catarina State University
European Physical Journal B | Year: 2013

Parameter plane plots related to a periodically forced compound Korteweg-de Vries-Burgers system, which is modeled by a third-order partial differential equation, are reported. It is shown that typical periodic structures embedded in a chaotic region in these parameter planes, organize themselves in different ways. There are bifurcation sequences whose periods have a well-defined law of formation, that may be written in a closed form, and there are bifurcation sequences self-organized in period-adding cascades. © 2013 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.

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