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Minas Gerais, Brazil

Januario Mendes J.,Federal University of Ouro Preto | Januario Mendes J.,Federal Institute of Minas Gerais | Cunha A.A.,Federal University of Ouro Preto | da S. Araujo F.G.,Federal University of Ouro Preto
Advanced Materials, Structures and Mechanical Engineering - Proceedings of the International Conference on Advanced Materials, Structures and Mechanical Engineering | Year: 2016

The evaluation of the behavior lump iron ores during the reduction process in blast furnace reactors is extremely important to determine the system’s productivity. To predict this behavior, one has to evaluate lump ores and pellets relative to chemical composition, physical properties, mineralogy, Reduction Degradation Index (RDI) and Reducibility Index (RI). This paper presents the evaluation of the chemical and metallurgical qualities of brazilian lump iron ores, when subjected to the reducing conditions present in the blast furnace. The procedures of the metallurgical tests are standardized by ISO and are performed in automated metallurgical testing ovens that allow real-time monitoring. The results obtained from the metallurgical tests permited to assess the differences in quality of three typologies of lump ores and how this may influence the productivity of the reactors. © 2016 Taylor & Francis Group, London. Source


Pereira L.E.S.,Federal Institute of Minas Gerais | Da Costa V.M.,Federal University of Juiz de fora
International Journal of Electrical Power and Energy Systems | Year: 2016

This letter proposes a simple and efficient starting process to be used in the interval power flow current injection at the maximum loading point. Load and line data uncertainties are considered. The proposed method is implemented in the Matlab environment using the Intlab toolbox. The main variables associated with the power flow problem are yielded in an interval form. Results are compared with those obtainable by Monte Carlo simulations. A large scale South-southeastern Brazilian network is used to validate the proposed starting process. © 2016 Elsevier Ltd. All rights reserved. Source


Pereira L.E.S.,Federal Institute of Minas Gerais | Da Costa V.M.,Federal University of Juiz de fora
International Journal of Electrical Power and Energy Systems | Year: 2014

This paper proposes a simple and efficient power flow method to calculate, in an interval manner, the main variables corresponding to the maximum loading point, under load data uncertainties. The resulting interval nonlinear system of equations is solved using Krawczyk method. The proposed methodology is implemented in the Matlab environment using the Intlab toolbox. Results are compared with those obtainable by Monte Carlo simulations. IEEE 30 bus system and a South-southeastern Brazilian network are used to validate the proposed methodology. © 2013 Elsevier Ltd. All rights reserved. Source


Da Silva S.,Federal University of Santa Catarina | Moreira B.,Federal Institute of Minas Gerais | Da Costa N.,Federal University of Santa Catarina
PloS one | Year: 2014

We replicate the Stanford marshmallow experiment with a sample of 141 preschoolers and find a correlation between lack of self-control and 2D:4D digit ratio. Children with low 2D:4D digit ratio are less likely to delay gratification. Low 2D:4D digit ratio may indicate high fetal testosterone. If this hypothesis is true, our finding means high fetal testosterone children are less likely to delay gratification. Source


Mapa S.M.S.,Federal University of Minas Gerais | Mapa S.M.S.,Federal Institute of Minas Gerais | Urrutia S.,Federal University of Minas Gerais
Information Processing Letters | Year: 2015

Disjunctively constrained versions of classic problems in graph theory such as shortest paths, minimum spanning trees and maximum matchings were recently studied. In this article we introduce disjunctive constrained versions of the Maximum Acyclic Subgraph problem. Negative disjunctive constraints state that a certain pair of edges cannot be contained simultaneously in a feasible solution. Positive disjunctive constraints enforces that at least one arc for the underlying pair is in a feasible solution. It is convenient to represent these disjunctive constraints in terms of an undirected graph, called constraint graph, whose vertices correspond to the arcs of the original graph, and whose edges encode the disjunctive constraints. For the Maximum Acyclic Subgraph problem under Negative Disjunctive Constraints we develop 1/2-approximative algorithms that are polynomial for certain classes of constraint graphs. We also show that determining if a feasible solution exists for an instance of the Maximum Acyclic Subgraph problem under Positive Disjunctive Constraints is an NP-Complete problem. © 2014 Elsevier B.V. All rights reserved. Source

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