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São João Evangelista, Brazil

Vaz C.T.,Federal University of Minas Gerais | Bracarense A.Q.,Federal University of Minas Gerais | Felizardo I.,ELBRAS Inc. | Pereira Pessoa E.C.,Instituto Federal Of Minas Gerais
Journal of Materials Research and Technology | Year: 2012

This paper evaluates the weld metal microstructure and properties of low hydrogen covered electrodes where the usual binders (potassium and sodium silicates) were replaced by polymers. The impermeable covered electrode was produced using the commercial E7018 formula. Preliminary tests with different polymers and formulation changes were realized to meet the satisfactory weld ability. The best covered electrode at the first stage was evaluated at the second stage. Weld metal diffusible hydrogen, microstructure and mechanical properties were evaluated and compared with traditional low hydrogen covered electrodes. In addition, it were made tests to evaluate the slag and fumes generated during the welding. The impermeable covered electrode diffusible hydrogen content was less than 4 mL/100 g of weld metal. This is very low if compared to conventional low hydrogen covered electrodes. Additional hydrogen tests were made after covered electrode moisture exposure under several conditions and confirm the coating resistance. The impermeable covered electrode weld metal showed the same morphology and typical microstructure of weld metal produced by the E7018 low hydrogen covered electrode. However, the acicular ferrite volume was significantly higher when compared with E7018 covered electrode. Weld metal tensile and yield strength, elongation and toughness (Charpy V-notch test) overcome the E7018 low hydrogen covered electrodes properties. The slag analysis showed the strongly polymer influence. © 2012 Elsevier Editora Ltda. and Brazilian Metallurgical, Materials and Mining Association. Source

da Silveira F.G.,Instituto Federal Of Minas Gerais | Silva F.F.E.,Federal University of Vicosa | Malhado P.L.S.C.,State University of Southwest Bahia
Revista Brasileira de Saude e Producao Animal | Year: 2012

The main objective of this work was to use the cluster analysis in order to classify nonlinear growth models in relation to different quality fit evaluators when data from the following lambs genetic groups were utilized: Dorper x Morada Nova, Dorper x Rabo Largo e Dorper x Santa Inês. After the choice of the best model, it was also aimed to apply the identity model test in order to identify the most efficient genetic group. The proposed methodology was applied to data of all animals from each group regarding twelve nonlinear models, whose fit quality was measured by determination coefficient, Akaike information criterion, Bayesian information criterion, mean quadratic error of prediction, predicted determination coefficient and convergence percentual. The cluster analysis indicated the von Bertalanffy as the best model for the three data sets. The model identity tests revealed that the Dorper x Santa Inês group presented higher adult weight, therefore this group is recommend for meat production. Source

Andalo V.,Instituto Federal Of Minas Gerais | Moino A.,Federal University of Lavras | Maximiniano C.,Federal University of Lavras | Campos V.P.,Federal University of Lavras | Mendonca L.A.,Instituto Nacional da Propriedade Industrial
Revista Colombiana de Entomologia | Year: 2011

Lipids represent the main source of energy in entomopathogenic nematodes. In the infective juvenile (IJ) phase, the level of such reserves can be influenced by storage, and this may affect their infectivity. The aim of this study was to evaluate the percentage of lipids and the associated infectivity in IJs of Steinernema carpocapsae, S. riobrave, Heterorhabditis sp. JPM4, Heterorhabditis sp. CCA and Heterorhabditis sp. PI that had been stored under different temperatures (8-28°C) for various times (0 to 180 days). The amounts of lipids present in IJs were evaluated histologically using a colorimetric method, while infectivity was assayed against Galleria mellonella larvae. Lipid levels diminished with increasing storage time for all nematodes, but the rates of decrease varied according to storage temperature and species. Lipid reserves were conserved for longer storage periods at 8, 16 and 20°C, while at 24 and 28°C the percentage of lipids decreased rapidly. The infectivities of IJs of Heterorhabditis spp. were less tolerant than those of Steinernema spp. to temperatures of 8, 24 and 28°C. Thus, while storage at 8°C was optimal for conserving lipid reserves, infectivity was best preserved at temperatures of 16 and 20°C gave rise to the least reduction in infectivities after 180 days of storage. In this way, lipids and infectivity are influenced by different storage temperatures for the species tested. These data are useful for greater success in using entomopathogenic nematodes as bio control agents. Source

Soares A.C.,University of Sao Paulo | De Oliveira R.M.,Instituto Federal Of Minas Gerais | Brisolari A.,University of Sao Paulo | Sales A.,Federal University of Sao Carlos | Goncalves D.,University of Sao Paulo
Scientia Forestalis/Forest Sciences | Year: 2011

Contact angle measurements, along with those of density, were performed in order to better understand the wetting characteristics of two types of wood; from Araucaria angustifolia and Pinus elliottii, under controlled experimental conditions. The use of a common thermal analysis technique, differential scanning calorimetry (DSC), did not lead to accurate conclusions about surface changes that occur with wood samples while increasing the temperatures to 200 °C. However, the results obtained here showed that the wettability of the wood samples decreased when the temperature reached 200 °C, and also, varied with time, sample type and fracture region. It did vary with time, sample type, and fracture region. A dramatic change in the wettability for both wood samples was verified from 120 °C to 140 °C, even before any considerable difference in mass loss and apparent density had been noticed. These measurements enable one to clearly distinguish between wood species which were thermally treated to 200 °C. Source

Rodrigues Filho F.A.,Federal University of Minas Gerais | Moreira T.A.A.,Instituto Federal Of Minas Gerais | Valle R.M.,Federal University of Minas Gerais | Baeta J.G.C.,Federal University of Minas Gerais | And 2 more authors.
Energy Conversion and Management | Year: 2016

Vehicular emissions significantly increase atmospheric air pollution and the greenhouse effect. This fact associated with the fast growth of the global motor vehicle fleet demands technological solutions from the scientific community in order to achieve a decrease in fuel consumption and CO2 emission, especially of fossil fuels to comply with future legislation. To meet this goal, a prototype stratified torch ignition engine was designed from a commercial baseline engine. In this system, the combustion starts in a pre-combustion chamber where the pressure increase pushes the combustion jet flames through a calibrated nozzle to be precisely targeted into the main chamber. These combustion jet flames are endowed with high thermal and kinetic energy being able to promote a stable lean combustion process. The high kinetic and thermal energy of the combustion jet flame results from the load stratification. This is carried out through direct fuel injection in the pre-combustion chamber by means of a prototype gasoline direct injector (GDI) developed for low fuel flow rate. During the compression stroke, lean mixture coming from the main chamber is forced into the pre-combustion chamber and, a few degrees before the spark timing, fuel is injected into the pre-combustion chamber aiming at forming a slightly rich mixture cloud around the spark plug which is suitable for the ignition and kernel development. The performance of the torch ignition engine running with E25 is presented for different mixture stratification levels, engine speed and load. The performance data such as combustion phasing, specific fuel consumption, thermal efficiency and the specific emissions of CO2 are carefully analyzed and discussed in this paper. The results obtained in this work show a significant increase in the torch ignition engine's performance in comparison with the baseline engine which was used as a workhorse for the prototype engine construction. © 2016 Elsevier Ltd. All rights reserved. Source

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