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Search Results: 1 - 10 of 567431 matches for " G. M. da; "
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Constru??o e avalia??o do desempenho de três abanadoras de sementes
Silva, José G. da;Soares, Dino M.;
Revista Brasileira de Engenharia Agrícola e Ambiental , 2006, DOI: 10.1590/S1415-43662006000100034
Abstract: usually, the available methods to trash cereal seeds do not provide a clean product, as required for commercialization, seeding and storage. for this purpose it is necessary to submit the seed lot to a cleaning process to eliminate grain fragments and other contaminants such as soil and plant particles. common processing procedures are not efficient and other methods available, more sophisticated, are not economically suitable for small farmers. the objective of this study was to construct three different blowers and evaluate their performance on rice: one provided with a foot operated fan; a second with an electric fan; and a third with electric fan and screeners. seed lots with different degrees of impurities and different machine feeding rates were used. greater operation efficiency was obtained for the least contaminated lot and smallest seeding rate. efficiency was considered adequate for seed lots up to 4% contamination level. for 6% impurity, seed lots had to be blown three times to lower impurity level less than 1%. seed loss was not significant.
CARACTERíSTICAS FíSICO-QUíMICAS E SENSORIAS DO TOMATE (Lycopersicon esculentum) PRODUZIDO POR CULTIVO ORG NICO EM COMPARA O AO CONVENCIONAL*
R. G. BORGUINI,M. V. da SILVA
Alimentos e Nutri??o , 2009,
Abstract: A pesquisa descreve as características físicoquímicas e sensoriais do tomate organico em compara o ao convencional. Amostras de tomate cultivares Carmem e Débora produzidos por cultivo organico e convencional foram avaliadas fisicamente, considerando-se a textura e cor, e quimicamente com rela o ao pH, sólidos solúveis totais e acidez total titulável. As amostras foram também avaliadas sensorialmente quanto ao aroma, sabor, cor e aspecto geral. Os frutos de tomate cultivar Débora e Carmem n o apresentaram diferen as com rela o à tonalidade de vermelho dos frutos provenientes do cultivo organico quando comparado ao convencional. Quanto à textura, os resultados se mostraram similares, entre o lote organico (8,85 N x 105) e convencional (8,47 N x 105) do cultivar Carmem. Para o cultivar Débora foram observados valores de 10,28 N x 105 e 9,38 N x 105 para o cultivo organico e convencional, respectivamente. Quanto aos valores de pH, sólidos solúveis totais e acidez total titulável, foram observadas diferen as entre os dois tipos de cultivo. A análise sensorial dos frutos, revelou diferen as significativas (p<0,05) entre os cultivos organico e convencional apenas para os atributos de sabor e aspecto geral. PALAVRAS-CHAVE: Tomate; análise sensorial; alimentos organicos.
Interactivity and Information- Communication Technologies in Chemical Engineering Classes  [PDF]
A. J. Santiago, C. E. da Silva, A. F. Machado, M. G. Muniz Washington
Open Journal of Social Sciences (JSS) , 2015, DOI: 10.4236/jss.2015.32002
Abstract:

In this paper, we propose a new contextualization of the so-called scientific method in teaching practices in science and engineering education. We report an objectification in information and communication technologies (ICT) for simulate the reaction rates during an class and its inclusion in the above-mentioned pedagogical purpose, that, in tune with the current realities of schools, rehearses reflections of a future with another horizon for teaching/learning engineering and other sciences.

Transferring Few-Layer Graphene Sheets on Hexagonal Boron Nitride Substrates for Fabrication of Graphene Devices  [PDF]
J. A. Leon, N. C. Mamani, A. Rahim, L. E. Gomez, M. A. P. da Silva, G. M. Gusev
Graphene (Graphene) , 2014, DOI: 10.4236/graphene.2014.33005
Abstract:

We have developed a dry transfer method that allows graphene to be transferred from polymer- thyl-methacrylate (PMMA)/Si (silicon) substrates on commercially available hexagonal boron ni- tride (hBN) crystals. With this method we are able to fabricate graphene devices with little wrin- kles and bubbles in graphene sheets, but that do not degrade the electronic quality more than the SiO2 substrate does. For hBN to perform the function described above substrate cleanliness is critical to get high quality graphene devices. Using hBN as a substrate, graphene exhibits enhanced mobility, reduced carrier inhomogeneity, and reduced intrinsic doping compared to graphene on SiO2 substrate.

Application of Photo-Fenton Process for the Treatment of Kraft Pulp Mill Effluent  [PDF]
M. D. Rabelo, C. R. Bellato, C. M. Silva, R. B. Ruy, C. A. B. da Silva, W. G. Nunes
Advances in Chemical Engineering and Science (ACES) , 2014, DOI: 10.4236/aces.2014.44050
Abstract: The present work evaluated the use of photo-Fenton process for the treatment of kraft pulp mill effluent. The photo-Fenton best operating conditions, such as pH, concentration, and H2O2: Fe2+ ratio were evaluated. The efficiency of the treatment was measured by COD (chemical oxygen demand) removal. The results showed that the optimum pH for the photo-Fenton process was equal to 3. The increase in H2O2 application resulted in an efficiency increase of the photo-Fenton process, although this was not a directly proportional relation. For most cases, the H2O2: Fe2+ proportion of 100:1 yielded the best results for COD removal. Solar radiation was more efficient than artificial UV to the COD removal. During the treatment the organic matter of the effluent was more oxidized than mineralized, showing a higher removal of COD than BOD (biochemical oxygen demand) and TOC (total organic carbon), respectively. So, photo-Fenton process increased the BOD/ COD ration but decreased the BOD/TOC ratio.
A influência simultanea do teor de alumina, da porosidade total e da temperatura na condutividade térmica de refratários sílico-aluminosos e aluminosos
Akiyoshi, M. M.;Silva, M. G. da;Silva, A. P. da;Pandolfelli, V. C.;
Ceramica , 2001, DOI: 10.1590/S0366-69132001000300007
Abstract: thermal conductivity of high alumina and fireclay refractories with 35.81 wt% £ al2o 3 £ 93.48 wt% and total porosity between 15% and 81% was evaluated by parallel hot-wire technique. the r ratio (alumina content / total porosity), applied in this work, allowed correlating the thermal conductivity (k) with chemical composition and the physical properties of the evaluated refractories. the least square method was used to generalize the correlation between k and r to larger temperature range. the high correlation obtained (r2 > 0.93) allows concluding that the use of r ratio is more effective in the thermal conductivity of refractory ceramics than using only the alumina content or the amount of corundum. these relationships obtained in this work are important in the project of furnaces and equipments that uses refractories. they are also suitable data to input computer simulation programs aiming to evaluate the thermomechanical behavior of refractory ceramics.
Condutividade térmica e sua correla??o com a temperatura e a massa específica volumétrica de materiais refratários sílico-aluminosos e aluminosos
Akiyoshi, M. M.;Silva, A. P. da;Silva, M. G. da;Pandolfelli, V. C.;
Ceramica , 2001, DOI: 10.1590/S0366-69132001000100005
Abstract: thermal conductivity was correlated to the properties of commercial refractory materials with bulk densities in the range of 0.55 g/cm3 and 3.14 g/cm3 and the total porosity between 15% and 81%. an empirical model correlating the thermal conductivity as a function of bulk density and temperature is presented and discussed. the proposed model provides a very fast route to estimate the thermal conductivity of refractories within the variation range of alumina content, bulk density and total porosity employed in this work. in order to apply the model, the only required property is the bulk density, which is commonly evaluated by the quality control during refractory production. statistical analysis are employed to validate the proposed empirical model.
Condutividade térmica e sua correla o com a temperatura e a massa específica volumétrica de materiais refratários sílico-aluminosos e aluminosos
Akiyoshi M. M.,Silva A. P. da,Silva M. G. da,Pandolfelli V. C.
Ceramica , 2001,
Abstract: Neste trabalho foram estudadas as correla es existentes entre a condutividade térmica e as características físicas de materiais refratários comerciais com massa específica volumétrica na faixa entre 0,55 g/cm3 e 3,14 g/cm3 e porosidade total compreendida entre 15% e 81%. é apresentado e discutido um modelo empírico que correlaciona a condutividade térmica como fun o da massa específica volumétrica, fornecendo assim uma forma rápida para estimar a condutividade térmica de materiais refratários em fun o da temperatura (dentro da faixa de varia o de teor de alumina, massa específica e porosidade empregados neste trabalho). Tal correla o é possível conhecendo-se apenas a massa específica volumétrica que é comumente avaliada no controle de qualidade durante a produ o de refratários. Análises estatísticas s o apresentadas para a valida o do modelo proposto.
A influência simultanea do teor de alumina, da porosidade total e da temperatura na condutividade térmica de refratários sílico-aluminosos e aluminosos
Akiyoshi M. M.,Silva M. G. da,Silva A. P. da,Pandolfelli V. C.
Ceramica , 2001,
Abstract: A condutividade térmica de materiais refratários sílico-aluminosos e aluminosos com 35,81%-p <= Al2O3 <= 93,48%-p e porosidade total entre 15% e 81% foi determinada através da técnica de fio quente paralelo. Além de avaliar as correla es entre a condutividade térmica, o teor de alumina (Al2O3) e a porosidade (PA e PT), neste trabalho, foi introduzida a raz o R (teor de alumina / porosidade total) que permitiu correlacionar a condutividade térmica simultaneamente com a composi o química e a microestrutura dos refratários. O método dos mínimos quadrados foi utilizado para generalizar a correla o entre k e R para uma faixa mais ampla de temperaturas. A boa qualidade do ajuste alcan ado pelo modelo empírico obtido (r2 > 0,93) permite concluir que a utiliza o da raz o R pode ser mais significa para a condutividade térmica de ceramicas refratárias do que a utiliza o do teor de alumina ou quantidade de coríndon isoladamente. Estas rela es s o fundamentais no projeto de fornos e equipamentos que empreguem ceramicas refratárias além de serem dados de entrada adequados para suprir programas de simula o computacional que visem à previs o do comportamento termomecanico destes materiais.
Irreversible processes and the accelerated-decelerated phases of the Universe
Kremer, G. M.;Silva, M. C. N. Teixeira da;
Brazilian Journal of Physics , 2004, DOI: 10.1590/S0103-97332004000600012
Abstract: a model for the universe is proposed where it is considered as a mixture of scalar and matter fields. the particle production is due to an irreversible transfer of energy from the gravitational field to the matter field and represented by a non-equilibrium pressure. this model can simulate three distinct periods of the universe: (a) an accelerated epoch where the energy density of the scalar field prevails over that of the matter field, (b) a past decelerated period where the energy density of the matter field becomes larger than the scalar field energy density, and (c) a present acceleration phase where the scalar field energy density overcomes the energy density of the matter field.
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