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Bottion A.J.B.,Federal Center for Technological Education of Minas Gerais | Barbi I.,Federal University of Santa Catarina
IEEE Transactions on Industrial Electronics | Year: 2015

This paper proposes a modular isolated dc-dc converter, based on the input-series and output-series association of the full-bridge PWM dc-dc converter with capacitive filter. The main attribute of the proposed architecture is its ability to provide self-balance of the input and output voltages across the individual converters, without voltage loop control scheme, both in the steady-state and transient operations. Circuit operation, theoretical analysis, and modeling are included in this paper, along with experimental results taken from a laboratory prototype with four modules, 1600-Vdc total input voltage, 1600-Vdc total output voltage, 4-kW output power, and 40-kHz switching frequency. Possible applications include high-voltage power supplies, solid-state transformers, dc current distribution systems, and renewable electric energy systems. © 2015 IEEE.

Panzera T.H.,Federal University of Sao Joao del Rei | Strecker K.,Federal University of Sao Joao del Rei | Miranda J.D.S.,Federal University of Sao Joao del Rei | Christoforo A.L.,Federal University of Sao Joao del Rei | Borges P.H.R.,Federal Center for Technological Education of Minas Gerais
Materials Research | Year: 2011

Steatite is a mineral which has been employed in the carving of elements in facades of Brazilian historical buildings and churches since the 17th century. Over the years, many of those historical buildings suffered the consequences of weathering with a current need for restoration. Recently a special cement-based mortar containing additions of fine powder waste from mineral extraction of steatite has been developed in Brazil, as a composite material for restoration of steatite elements. However, the incorporation of steatite waste reduces the flexural strength of the mortar and compromises the restoration of elements where gravity imposes tensile stresses. The addition of carbon fibres may overcome this issue and increase the flexural strength of the cement-steatite composite mortar. This work investigates the effect of carbon fibre addition on the bulk density and flexural strength of compacted precast cement-steatite composites. The results show that the addition of carbon fibres (i) effectively increases the mechanical strength, allowing for a higher amount of steatite powder waste in the mixes; (ii) reduces the weight of the structural elements. This new composite material would help to develop restoration techniques of historical buildings and serve as a disposal route of steatite powder waste in Brazil. © 2011.

Bento Bottion A.J.,Federal Center for Technological Education of Minas Gerais | Barbi I.,Federal University of Santa Catarina
Proceedings of the IEEE International Conference on Industrial Technology | Year: 2015

This paper proposes a modular isolated DC-DC converter based on the series-series association of Dual Active Bridge (DAB) converters. The main attribute of the proposed topology is its ability to provide self-balance of the voltages on both sides of each individual converter, without voltage loop control, both in steady state and transient operations due to the natural circuit losses. Other important attributes are the voltage stress reduction in switches, due to the series-series association, and the fact that it has bidirectional power flow capability. The study of capacitor voltage balancing mechanism and theoretical analysis are included in the paper along with experimental results obtained from a prototype with two modules, 400 Vdc on the source side A and 400 Vdc on the load side B, 400 W of power, and 40 kHz switching frequency. Certain possible applications include high-voltage bidirectional direct current source supplies and interconnection of high-voltage direct current (HVDC) transmission lines. © 2015 IEEE.

Protasio T.P.,Federal University of Lavras | Bufalino L.,Federal University of Lavras | Tonoli G.H.D.,Federal University of Lavras | Guimaraes Junior M.G.,Federal Center for Technological Education of Minas Gerais | And 2 more authors.
BioResources | Year: 2013

The aim of this paper was to analyze energy-related properties of forestry and agricultural wastes for energy production purposes, and to compare them with fossil fuels. The forestry wastes used were red cedar, Eucalyptus, and Pinus wood shavings. The agricultural wastes analyzed were rice husk, coffee wastes, sugar cane bagasse, maize harvesting wastes, and bamboo cellulose pulp. The forestry wastes presented more suitable properties for bioenergy production than the agricultural wastes. Desirable energetic properties were found for coffee wastes. The opposite was verified for rice husks. Among the biomass studied, coffee wastes presented the highest equivalent in fossil fuel volume and hence may lead to the highest decrease in CO2 emissions by fossil fuels used in Brazil for steam and heat production. The results suggests that CO2 benefits can be obtained if bioenergy is generated in the same locale where biomass is produced, avoiding CO2 cost of logistics and leading to greater end-use efficiency. The present work promotes the widespread use of different lignocellulosic wastes for bioenergy production and gives useful information for the planning and the control of power plants using biomass.

De Assis C.F.C.,Federal Center for Technological Education of Minas Gerais | Tenorio J.A.S.,University of Sao Paulo | Nath N.K.,University of Pune
Energy and Fuels | Year: 2014

Focus on environmental issues has greatly increased in recent years. This development has led to a competitive advantage for innovative processes that are less harmful to the environment, because they satisfy the environmental consciousness of todays consumers, enable entrance into more competitive new markets, can even lead to direct profits in accordance with environmental conservation, and earn carbon credits by recycling greenhouse gases. such as CO2 and CH4. The present paper shows the feasibility of using biomass, such as rice husk, sugar cane bagasse, elephant grass, coffee husk, and eucalyptus bark, as substitute materials for powder coal injection into a blast furnace, thereby leading to the replacement of part or even all of coal injected, which is not renewable and causes great environmental impact during mining and extraction. To simulate the possibility of injecting biomass materials, physical modeling, which has been developed for this purpose, is used. Further analyses are particle size classification, surface area, calorific value, and proximate and ultimate analyses. It has been concluded that, using these biomass materials, it is possible to reduce the specific carbon consumption in the blast furnace burden, which enhances the environmental commitment of the steel plant, and, moreover, to use waste generated in agriculture. © 2014 American Chemical Society.

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