Capim braquiaria.

bitstream/item/69612/1/IPEAN-CulturasAmazonia2.pd

Exploring spatial patterns of GCM projection bias via model based geostatistics.

General Circulation Models (GCMs) are numerical models developed to represent physical processes in the atmosphere, ocean, cryosphere and land surface. They constitute the most advanced tool currently available for simulating future climate scenarios as a response to increasing greenhouse gas concentrations. GCMs, possibly in conjunction with nested regional climate models (RCMs), have the potential to provide consistent estimates of regional climate change which are required in climate impact assessments. The characterization of model bias in terms of magnitude and spatial patterns is part of the process of evaluating the model performance via hindcast skill analysis, an important preliminary step in climate change impact assessments. In this paper, we discuss how Model Based Geostatistics can be applied for exploring bias patterns, key information for performing bias correction of GCM or RCM projections in future time slices. As example, we present an assessment of annual rainfall projection bias for three GCMs across the Northeast Brazil

Creep analysis of a GRP cylinder under hydrostatic test / Análise de fluência de um cilindro GRP sob teste hidrostático

The GRP (Glass Reinforced Polymer) has been widely used in several industrial applications mainly due to its low cost, high availability, and easy manufacturing process. The matrix made by a combination of glass fibers and epoxy offers good engineering properties for the composite material. This study aims to investigate the creep behavior of a glass fiber/epoxy composite cylinder when it was subjected to hydrostatic pressure at room temperature, and when heated at 50ºC. The geometrical viscoelastic deformation was identified by processing signal data positioned on the cylinder surface. Then, electronic data processing was performed to obtain the characteristic of the creep phase phenomenon attributed to this polymeric composite. The cylindrical specimen has been manufactured using a 4-axis CNC (Computer Numeric Control) filament winding machine, which is equipment designed to produce cylindrical components in the composite industry. A creep test was performed by submitting the cylinder to a hydrostatic load for 500 hours, with a controlled injection of fluid up to a 50 bar pressure. Moreover, fiber volume fraction and composite density were determined to control de manufacturing parameters. The results showed that the glass transition temperature of the composite was 120°C. This also indicated a high level of reliability in the manufacturing parameters of the composite specimen. In the experiment carried out at 50ºC, the polymer matrix showed a loss of stiffness, which contributed to increased strain levels in the composite material. The structure did not show a significant creep effect after 500 hours, ensuring good dimensional and structural stability from the cylinder. Once the creep test finished, the cylinder was submitted to increase the pressure level to rupture. The microstructure was also evaluated using scanning electron microscopy (SEM). The SEM analyses presented a good agreement with the filament winding manufacturing parameters and showed the excellent quality of impregnation between glass fiber and epoxy resin applied on the cylinder specimen. The images presented evidence of an excellent adhesion of the fiber into the matrix, contributing to a good performance of the composite

Efeito da pré-polimerização na síntese de resinas de troca iônica contendo ácido acrílico

Este trabalho estuda duas rotas de síntese para a obtenção de resinas poliméricas de troca catiônica compostas por ácido acrílico, estireno e divinilbenzeno a fim de compreender o impacto da inclusão de uma etapa de pré-polimerização do ácido acrílico com estireno no teor de ácido acrílico incorporado ao polímero. Ambas as rotas foram realizadas por meio da técnica de polimerização em suspensão divergindo apenas na inclusão da etapa de pré-polimerização em uma delas. Após as sínteses, as resinas foram submetidas a análises espectroscópicas e titulométricas para, assim, averiguar suas diferenças quanto ao teor de ácido acrílico incorporado. Foi possível concluir que a etapa de pré-polimerização não contribuiu efetivamente para uma maior incorporação de sítios carboxílicos em relação a síntese direta

Explaining the water: holding capacity of biochar by scanning electron microscope images.

O objetivo deste estudo foi identificar biocarvão com melhor desempenho de promover o aumento da capacidade de retenção de água no solo, com base em evidências de laboratório e avaliação de porosidade microestructural

New taxa of eriphyid mites (Acari:Eriophyidae) from fruit trees in Norteastern Brazil.

Made available in DSpace on 2018-06-07T01:01:56Z (GMT). No. of bitstreams: 1 ID29135126.pdf: 618659 bytes, checksum: ea96a9ebef8429f119c343bf82e86d0a (MD5) Previous issue date: 2008-02-14bitstream/item/178230/1/ID-29135-1-2-6.pd