Time filter

Source Type

Monteria, Colombia

Castro-Nunez M.,University of Calgary | Castro-Puche R.,University of Cordoba, Colombia
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2012

An alternative circuit analysis technique and its associated power theory is compared to the IEEE Standard 1459 and the current's physical components power theory. The comparison shows that elimination of the fundamental reactive power quantity Q1 as defined by the Standard does not ensure supply current reduction. In contrast elimination of the reactive current as defined by the CPC power theory ensures supply current reduction. However, the balance principle of the reactive power cannot be applied to the CPC power theory as the definition of the reactive power is not a signed quantity. The alternative method which uses geometric algebra instead of complex numbers, multivectors in place of phasors and the Euclidian cal N-dimensional space instead of the frequency domain succeeds in defining a decomposition that accounts for the total nonactive power, and also satisfies conservation. The alternative circuit analysis technique allows viewing the flow of currents and energy/powers in the circuits under examination. Additionally, the paper provides 4 reasons why the present definition of apparent power defined as the product of the magnitude of current and voltage is unsuitable for nonsinusoidal circuits in the G N domain. © 2004-2012 IEEE.

Castro-Nunez M.,University of Calgary | Castro-Puche R.,University of Cordoba, Colombia
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2012

An alternative circuit analysis technique is used to study networks with nonsinusoidal sources and linear loads. In contrast to the technique developed by Steinmetz, this method is supported by geometric algebra instead of the algebra of complex numbers, uses multivectors in place of phasors and is performed in the G N domain instead of the frequency domain. The advantages of this method over the present technique involve: determining the flow of current and power quantities in the circuit, validating the results using the principle of conservation of energy, discerning and revealing other forms of reactive power generation, and the ability to design compensators with great flexibility. The power equation is composed of the active power and the CN-power representing the nonactive power. All the CN-power terms are sorted into reactive power terms due to phase shift, reactive power terms due to harmonic interactions and degrading power terms which determine the new quantity called degrading power. This decomposition shows that estimating these quantities is intricate. It also displays the power equation's functionality for power factor improvement. The geometric addition of power quantities is not pre-established but results from applying the established norm and yields the new quantity called net apparent power. © 2012 IEEE.

Martinez-Florez G.,University of Cordoba, Colombia | Bolfarine H.,University of Sao Paulo | Gomez H.W.,University of Antofagasta
Biometrical Journal | Year: 2013

We develop regression models for limited and censored data based on the mixture between the log-power-normal and Bernoulli-type distributions. A likelihood-based approach is implemented for parameter estimation and a small-scale simulation study is conducted to evaluate parameter recovery, with emphasis on bias estimation. The main conclusion is that the approach is very much satisfactory for moderate and large sample sizes. A real data example, the safety and immunogenecity study of measles vaccine in Haiti, is presented to illustrate how different models can be used to fit this type of data. As shown, the asymmetric models considered seem to present the best fit for the data set under study, revealing significance of the explanatory variable sex, which is not found significant with the log-normal model. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Espriella N.D.L.,Simon Bolivar University of Venezuela | Espriella N.D.L.,University of Cordoba, Colombia | Buendia G.M.,Simon Bolivar University of Venezuela
Journal of Physics Condensed Matter | Year: 2011

We perform Monte Carlo simulations in order to study the magnetic properties of the mixed spin-S = ±3/2,±1/2 and spin-σ = ±5/2,±3/2,±1/2 Ising model. The spins are alternated on a square lattice such that S and σ are nearest neighbors. We found that when the Hamiltonian includes antiferromagnetic interactions between the S and σ spins, ferromagnetic interactions between the spins S, and a crystal field, the system presents compensation temperatures in a certain range of the parameters. The compensation temperatures are temperatures below the critical point where the total magnetization is zero, and they have important technological applications. We calculate the finite-temperature phase diagrams of the system. We found that the existence of compensation temperatures depends on the strength of the ferromagnetic interaction between the S spins. © 2011 IOP Publishing Ltd.

Brango C.B.,University of Cordoba, Colombia
Physica D: Nonlinear Phenomena | Year: 2012

The focus of the present work is the Symmetric Regularized-Long-Wave equation. We prove that the initial value problem for this equation is locally and globally well-posed in Hpers×Hpers-1 and Hs(R)×Hs- 1(R), if s<0. We also prove the existence and nonlinear stability of periodic travelling wave solutions, of cnoidal type, for the equation mentioned above. © 2011 Elsevier B.V. All rights reserved.

Discover hidden collaborations