855 resultados para sub-tropical and tropical climates


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In this work, the plate bending formulation of the boundary element method (BEM), based on the Reissner's hypothesis, is extended to the analysis of plates reinforced by rectangular beams. This composed structure is modelled by a zoned plate, being the beams represented by narrow sub-regions with larger thickness. The integral equations are derived by applying the weighted residual method to each sub-region, and summing them to get the equation for the whole plate. Equilibrium and compatibility conditions are automatically imposed by the integral equations, which treat this composed structure as a single body. In order to decrease the number of degrees of freedom, some approximations are considered for both displacements and tractions along the beam width. The accuracy of the proposed model is illustrated by simple examples whose exact solution are known as well as by more complex examples whose numerical results are compared with a well-known finite element code.

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This study presents the results obtained in a field experiment carried out at Glicério, Northwest of São Paulo state, Brazil, whose objective was to analyze changes of selected soil physical properties and water infiltration rates on a Yellow-Red Latosol, under three different management conditions. The experimental design was arranged as completely randomized split-block with twelve treatments, which corresponded to four depths (0-0.05 m; 0.05-0.10 m; 0.10-0.20 m and 0.20-0.40 m) and three conditions of soil use and management with four replications. The soil surface conditions were: conventional tillage (one disking with moulboard plus two levelling passes with harrow), nine months before starting filed experiences; recent conventional tillage (also one disking with moulboard plus two levelling passes with harrow) and native forest. The conventional tillage areas were cropped for about fifteen years with annual cultures. The considered soil general physical properties were: macroporosity, microporosity, total porosity, bulk density, soil moisture and penetration resistance and, in addition; soil water infiltration rates were also recorded. According to our results, differences on general soil physical properties and infiltration rates appeared when both tilled sub-treatments and native forest were compared. Both, plots recently prepared by conventional tillage and those prepared by tillage but left nine months in rest, presented a statistically significant decrease of constant (final) water infiltration rates of 92.72% and 91.91% when compared with native forest plots.

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The vegetative propagation of Dovyalis hebecarpawas studied using herbaceous cuttings of a hybrid introduced in Brazil by the College of Agriculture, Campus of Jaboticabal-UNESP. The treatments consisted of (1) evaluating the effect of five 3-Indolebutyric acid (IBA) doses (0 (control), 1,000, 3,000, 5,000 and 7,000 mg.L -1); (2) the influence of two kinds of herbaceous cuttings (apical and sub-apical) and (3) the collection position on the plant (upper and lower part of the canopy) at two different times of the year (autumn and spring). The experimental design was completely randomized with four replicates of 10 cuttings each; the analysis was on a 5 × 2 × 2 factorial layout. The growth regulator (IBA) did not influence the rooting of cuttings in either sampling season. The best season for the rooting was spring. Apical cuttings were desirable for rooting in both seasons. In autumn cuttings taken from the lower portion of the plant showed significantly higher rooting values than the ones from the upper portion; and in spring cuttings taken from the upper portion had higher rooting percentages. © 2007 by The Haworth Press. All rights reserved.

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Distributed Generation, microgrid technologies, two-way communication systems, and demand response programs are issues that are being studied in recent years within the concept of smart grids. At some level of enough penetration, the Distributed Generators (DGs) can provide benefits for sub-transmission and transmission systems through the so-called ancillary services. This work is focused on the ancillary service of reactive power support provided by DGs, specifically Wind Turbine Generators (WTGs), with high level of impact on transmission systems. The main objective of this work is to propose an optimization methodology to price this service by determining the costs in which a DG incurs when it loses sales opportunity of active power, i.e, by determining the Loss of Opportunity Costs (LOC). LOC occur when more reactive power is required than available, and the active power generation has to be reduced in order to increase the reactive power capacity. In the optimization process, three objectives are considered: active power generation costs of DGs, voltage stability margin of the system, and losses in the lines of the network. Uncertainties of WTGs are reduced solving multi-objective optimal power flows in multiple probabilistic scenarios constructed by Monte Carlo simulations, and modeling the time series associated with the active power generation of each WTG via Fuzzy Logic and Markov Chains. The proposed methodology was tested using the IEEE 14 bus test system with two WTGs installed. © 2011 IEEE.

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Hyperbaena domingensis (DC.) Benth. has new records for the Atlantic Forest from northeastern Brazil. It is found in lowland coastal, sub-montane and montane remnants of Atlantic Forest as part of the forest canopy or drape dover edge shrubs and treelets. It can be recognized by the ovate to oblong leaves, spiciform or paniculiform inflorescence, dichlamydeous and 3-merous flowers, drupaceous and purple (at maturity) fruits, and horseshoe-shaped seeds. Comments, distribution map, and pictures are presented here. © 2012 Check List and Authors.

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Potassium, like nitrogen, it constitutes an essential element for growth, development and production of cotton crops. Moreover, these elements are directly related to fiber formation and when provided in suitable doses, influences its quality. The aim of the experiments was to evaluate the influence of potassium on biometric parameters, yield and quality of cotton fibers. For this purpose, plants of the cultivar Delta opal were grown in a greenhouse with altered potassium fertilization, simulating K deficiency and two overdoses. During the different phenological stages, biometric variables were analyzed including the production of fibers and their qualitative parameters. The sub-dose and the overdoses treatments of K, changed all the evaluated parameters, demonstrating the importance of potassium fertilizer on them.

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Pós-graduação em Alimentos e Nutrição - FCFAR

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Pós-graduação em Física - IGCE

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Pós-graduação em Geociências e Meio Ambiente - IGCE

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Pós-graduação em Geociências e Meio Ambiente - IGCE

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)