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Search Results: 1 - 10 of 490464 matches for " Edson A;Oliveira "
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Relaxation to Fixed Points in the Logistic and Cubic Maps: Analytical and Numerical Investigation
Juliano A. de Oliveira,Edson R. Papesso,Edson D. Leonel
Entropy , 2013, DOI: 10.3390/e15104310
Abstract: Convergence to a period one fixed point is investigated for both logistic and cubic maps. For the logistic map the relaxation to the fixed point is considered near a transcritical bifurcation while for the cubic map it is near a pitchfork bifurcation. We confirmed that the convergence to the fixed point in both logistic and cubic maps for a region close to the fixed point goes exponentially fast to the fixed point and with a relaxation time described by a power law of exponent -1. At the bifurcation point, the exponent is not universal and depends on the type of the bifurcation as well as on the nonlinearity of the map.
Influência da temperatura no desempenho mecanico de compósitos PEI/fibras de vidro
Oliveira, Gustavo H.;Guimar?es, Valdir A.;Botelho, Edson C.;
Polímeros , 2009, DOI: 10.1590/S0104-14282009000400010
Abstract: polymeric composites have been used due to the technological progress in industries, mainly the aerospace. these advances are aimed at obtaining composites with low specific gravity associated with high mechanical properties and stiffness. the main advantages of thermoplastics over thermoset laminates include: fast processing due to the absence of a cure cycle, low moisture absorption, excellent chemical resistance; higher service temperature; low costs of transport and storage, higher impact resistance; higher stiffness and possibility of recycling. it is therefore important to investigate the mechanical properties at high temperatures since these materials are subjected to large temperature variations in aeronautical applications. this work is aimed at evaluating the mechanical properties (tensile, fatigue and interlaminar shear behavior) of pei reinforced with glass fiber at 25 and 80 °c. the tensile, shear and fatigue stresses for pei/glass fiber were found to be higher than in epoxy/glass fiber laminates. however, in all cases a significant deterioration in the mechanical properties was observed at 80 °c in comparison to those at room temperature.
Estudio del Secado de Anacardo (Anacardium occidentale L.) mediante Secador Solar de Radiación Directa
Machado,Ant?nio V; Oliveira,Edson L; Santos,Everaldo S; Oliveira,Jackson A;
Información tecnológica , 2010, DOI: 10.4067/S0718-07642010000100006
Abstract: in this work solar drying tests with direct radiation and its mathematical modeling to evaluate the kinetics of cashew-nut (anacardium occidentale l.) drying comparing their efficiency concerned to natural solar drying board are presented. the experiments were performed using fruit slices with 1 cm and 2 cm of thickness, obtaining its water content versus time. using a direct solar radiation dryer, the drying time was lower than that of natural drying board, therefore adding value to products. diffusivity values obtained from water sliced fruits were similar to other data available in the literature. the dried products had good organoleptic properties, aroma, color and crunchy texture.
Estudio del Secado de Anacardo (Anacardium occidentale L.) mediante Secador Solar de Radiación Directa Cashew-nut (Anacardium occidentale L.) Drying Study Using a Solar Dryer with Direct Radiation
Ant?nio V Machado,Edson L Oliveira,Everaldo S Santos,Jackson A Oliveira
Información Tecnológica , 2010,
Abstract: Se presentan ensayos de secado con radiación solar directa y su modelado matemático, para evaluar la cinética de secado del anacardo (Anacardium occidentale L.) y comparar su eficiencia en relación al secado solar natural en tablero. Los experimentos fueron realizados con rodajas de fruta de 1 cm. y 2 cm. de espesor, obteniendo su contenido acuoso versus tiempo. Con el empleo del secador solar de radiación directa, se redujo el tiempo de secado en relación al secado natural en tablero, agregando valor a los productos. Se obtuvo valores de difusividad de agua en rodajas de frutos del mismo orden de otros datos de la literatura. Los productos secados resultaron tener buenas propiedades organolépticas, tales como sabor, aroma, color y textura crocante. In this work solar drying tests with direct radiation and its mathematical modeling to evaluate the kinetics of cashew-nut (Anacardium occidentale L.) drying comparing their efficiency concerned to natural solar drying board are presented. The experiments were performed using fruit slices with 1 cm and 2 cm of thickness, obtaining its water content versus time. Using a direct solar radiation dryer, the drying time was lower than that of natural drying board, therefore adding value to products. Diffusivity values obtained from water sliced fruits were similar to other data available in the literature. The dried products had good organoleptic properties, aroma, color and crunchy texture.
The Lévy Map: A two-dimensional nonlinear map characterized by tunable Lévy flights
J. A. Mendez-Bermudez,Juliano A. de Oliveira,Edson D. Leonel
Physics , 2014, DOI: 10.1103/PhysRevE.90.042138
Abstract: Once recognizing that point particles moving inside the extended version of the rippled billiard perform L\'evy flights characterized by a L\'evy-type distribution $P(\ell)\sim \ell^{-(1+\alpha)}$ with $\alpha=1$, we derive a generalized two-dimensional non-linear map $M_\alpha$ able to produce L\'evy flights described by $P(\ell)$ with $0<\alpha<2$. Due to this property, we name $M_\alpha$ as the L\'evy Map. Then, by applying Chirikov's overlapping resonance criteria we are able to identify the onset of global chaos as a function of the parameters of the map. With this, we state the conditions under which the L\'evy Map could be used as a L\'evy pseudo-random number generator and, furthermore, confirm its applicability by computing scattering properties of disordered wires.
Scaling Properties of a Hybrid Fermi-Ulam-Bouncer Model
Diego F. M. Oliveira,Rafael A. Biz o,Edson D. Leonel
Mathematical Problems in Engineering , 2009, DOI: 10.1155/2009/213857
Abstract: Some dynamical properties for a one-dimensional hybrid Fermi-Ulam-bouncer model are studied under the framework of scaling description. The model is described by using a two-dimensional nonlinear area preserving mapping. Our results show that the chaotic regime below the lowest energy invariant spanning curve is scaling invariant and the obtained critical exponents are used to find a universal plot for the second momenta of the average velocity.
Distribui??o espacial de formigueiros de Acromyrmex crassispinus (Forel)(Hymenoptera: Formicidae) em plantios de Pinus taeda
Nickele, Mariane A;Oliveira, Edilson B de;Reis Filho, Wilson;Iede, Edson T;Ribeiro, Rodrigo D;
Neotropical Entomology , 2010, DOI: 10.1590/S1519-566X2010000600003
Abstract: the spatial distribution of insects is essential to perform control strategies, to improve sample techniques and to estimate economic losses. we aimed to determine the spatial distribution of nests of acromyrmex crassispinus (forel) in pinus taeda plantations. the experiments were carried out in p. taeda plantations with different ages (treatments: recently-planted, three and six-year old plants). the study took place in rio negrinho and in três barras, sc. three plots of one hectare were delimited in each treatment, and plots were divided in 64 sample units. the analysis of the dispersion index [variance/mean relationship (i), index of morisita (iδ) and k exponent of negative binomial distribution] showed that the majority of the samplings presented random distribution. among the three distributions of probabilities studied: poisson, positive binomial and negative binomial, the poisson distribution was the best model to fit the spatial distribution of a. crassispinus nests in all samplings. the result was a random distribution in the plantings of different ages.
Formation of beetroot seedlings in different protected environments, substrates and containers in Aquidauana region, State of Mato Grosso do Sul, Brazil
Oliveira, Letícia C. de;Costa, Edilson;Cortelassi, Julissandra A. da S.;Rodrigues, Edson T.;
Engenharia Agrícola , 2012, DOI: 10.1590/S0100-69162012000300001
Abstract: this study with beetroot seedlings, cultivar top tall early wonder, was carried out at the state university of mato grosso do sul (uems/aquidauana), from october to november 2008. three environments of cultivation were used: greenhouse; nursery with monofilament screen of 50 % of shading; and nursery with aluminized thermal reflective screen of 50% of shading. in these environments, three polystyrene trays of 72, 128 and 200 cells, filled with four substrates, were tested: soil; plantmax?; coconut fiber and vermiculite. there were no replication environments and then each one was considered an experiment alone. for each environment, it was adopted a completely randomized design in factorial scheme 3x4 (three trays x four substrates), with four replications, performing individual analysis of variance and joint analysis of experiments for environment comparisons. the monofilament screen is the best environment for seedlings produced in tray of 72 cells, and the greenhouse was the best environment for seedlings produced in trays of 128 cells. the best seedlings were formed in the tray of 72 cells. vermiculite was the best substrate.
Electrocatalytic oxidation of methanol: study with Pt:Mo dispersed catalysts
Oliveira Neto, Almir;Perez, Joelma;Napporn, Wilhelmin T.;Ticianelli, Edson A.;Gonzalez, Ernesto R.;
Journal of the Brazilian Chemical Society , 2000, DOI: 10.1590/S0103-50532000000100008
Abstract: the electrocatalytic oxidation of methanol on pt:mo dispersed on carbon prepared using an alternative method recently developed in this laboratory was investigated. the edx analysis confirmed that the simultaneous reduction of the precursor salts of pt and mo leads to the presence of these materials at the nominal composition initially calculated. the addition of mo to pt causes an increase of the oxidation currents, but does not improve the catalytic effect for methanol oxidation. tafel plots for various methanol concentrations showed the presence of two slopes. on line differential electrochemical mass spectrometry (dems) was used to investigate the distribution of products and intermediates in methanol oxidation.
Effect of Organic Matter on Manganese Solubility
Andrade, Emilene;Miyazawa, Mário;Pavan, Marcos A.;Oliveira, Edson L. de;
Brazilian Archives of Biology and Technology , 2002, DOI: 10.1590/S1516-89132002000100003
Abstract: the objective of this study was to re-evaluate some aspects of the relative importance of organic matter on mn solubility in acid soil conditions. field study showed that black oats, oil seed radish, elephant grass, lupin, leucaena, and coffee leaves serving as mulch decreased mn solubility as compared with bare soil. the decrease in mn solubility with plant mulch was related to increase in soil moisture content. laboratory study showed that increasing temperature from 25 to 100oc increased mn solubility and total soil organic carbon was little changed; from 150 to 200oc increased both mn solubility and organic carbon oxidation, and up to 300oc decreased mn solubility and stoped organic carbon oxidation . aluminum solubility always increased with increasing temperature. organic matter exerted a control in both mn and al solubilities in acid soils.
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