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Rio de Janeiro, Brazil

Da Costa Bortoni E.,Federal University of Itajuba | Siniscalchi R.T.,Furnas Centrais Eletricas | Jardini J.A.,University of Sao Paulo
IEEE Transactions on Energy Conversion | Year: 2011

The calorimetric method has for a long time been applied for energy conversion efficiency measurement in electrical machines. The number of temperature sensors necessary for its successful application in the field constitutes in one of the major drawbacks of the method. This paper shows how the usage of IR thermal imaging techniques can reduce costs and the necessary time for the calorimetric method application. In addition, contribution to the heat transfer coefficient determination and a new approach to consider conduction losses in the generator shaft are also presented. © 2011 IEEE. Source

Araujo F.G.,Federal Rural University of Rio de Janeiro | Costa De Azevedo M.C.,Federal Rural University of Rio de Janeiro | Lima Ferreira M.D.N.,Furnas Centrais Eletricas
Lake and Reservoir Management | Year: 2011

The water quality of a eutrophic tropical reservoir was studied over a 5-year period (2000-2004), with quarterly sampling (Jan, Apr, Jul, and Oct) carried out at 3 sampling stations with one station in each of 3 zones (fluvial, transitional, and lacustrine). During the wet season, large amounts of phosphorus were introduced into the reservoir by the increased inflow of the river. Dissolved oxygen, pH, and chlorophyll a levels peaked in the wet season; pH, chlorophyll a, and total phosphorus in several cases were recorded above the recommended Brazilian guidelines. Dissolved oxygen was lower than acceptable levels in the euphotic layer and reached very low levels in the hypolimnion, indicating thermal stratification. Efficient reservoir management is necessary to restore environmental quality, and our results indicate that selective withdrawal may be an effective means of improving the quality of water in Funil Reservoir. © Copyright by the North American Lake Management Society 2011. Source

Dester M.,Furnas Centrais Eletricas
IEEE Latin America Transactions | Year: 2016

Integration of renewable sources into Brazils power mix is desirable and necessary. The main benefit from these energy sources is maintaining greenhouse gas emissions at low levels. Nevertheless, high penetration of these energy sources into the power mix can lead to many problems, for instance, intermittency in power generation. There are some mechanisms which can be implemented to mitigate intermittency and allow a higher level of participation of these energy sources in the generation mix. One such mechanism is utilizing Energy Storage Systems (ESS). The goal of this paper is to perform a study to find the best ESS options using Multi-criteria Decision Analysis. Moreover, an examination regarding Hydro Power Plants' reservoirs as an ESS is accomplished through a case study using three of Brazils significant Hydro Power Plants. © 2003-2012 IEEE. Source

It is very important that the chemical contents are related to the daily life of the student in order to favor the understanding of the social context in which they are inserted. For this to occur the teacher can appropriate the elaboration of didactic sequences to assist you in choosing the best teaching-learning resources to be worked in the classroom, such as games, experiments and activities that favor the contextualization of the contents. In seeking work in this way the contents, from the elaboration of didactic sequences, these will contribute to arouse curiosity, motivation and participation of students in class and encouraging the teaching and learning process. From this perspective the present article focused on the development of a didactic sequence for the chemical content acid, where from that the teacher can work in the classroom various teaching resources for the content herein. However they were developed different methods to teach the chemical content acid and base, using so experimentation, making a game and a contextualized approach. The choice of the methodology presented here it was with the intention that, from this use can encourage a better use of the content by the students and that they can better understand the content and the relationship of chemistry with your social context. © 2015. Porto Alegre, RS. Brasil. Source

Rego J.H.S.,University of Brasilia | Nepomuceno A.A.,University of Brasilia | Figueiredo E.P.,Federal University of Goais | Hasparyk N.P.,Furnas Centrais Eletricas
Construction and Building Materials | Year: 2015

Residual rice husk ash (RHA) has been frequently suggested as possible mineral addition in cements. However, the characteristics of residual RHAs produced by different manufacturers and the effect of residual RHA with low amorphous silica content in addition in cement pastes are poorly understood. This paper aims at characterizing the different varieties of residual RHA produced in Brazil and at investigating the microstructure of cement pastes with 20% replacement of ordinary cement by RHAs which presents high and low amorphous silica content. A broad array of techniques was employed in the characterization, such as X-ray diffraction (XRD), thermogravimetric analysis (TG), scanning electron microscopy (SEM), X-ray microanalysis, and porosimetry by mercury intrusion (PMI). The results demonstrate that RHA with low amorphous silica content, finely divided, reduces the calcium hydroxide content and the Ca/Si ratio of calcium silicate hydrate (C-S-H), and also refines the porous structure of the pastes. Residual RHAs with low amorphous silica content thus proved to be suitable mineral addition for cements. © 2015 Elsevier Ltd.All rights reserved. Source

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