5,613 research outputs found

    A new data reduction scheme to obtain the mode II fracture properties of Pinus Pinaster wood

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    In this work a numerical study of the End Notched Flexure (ENF) specimen was performed in order to obtain the mode II critical strain energy released rate (GIIc) of a Pinus pinaster wood in the RL crack propagation system. The analysis included interface finite elements and a progressive damage model based on indirect use of Fracture Mechanics. The difficulties in monitoring the crack length during an experimental ENF test and the inconvenience of performing separate tests in order to obtain the elastic properties are well known. To avoid these problems, a new data reduction scheme based on the equivalent crack concept was proposed and validated. This new data reduction scheme, the Compliance-Based Beam Method (CBBM), does not require crack measurements during ENF tests and additional tests to obtain elastic properties.FCT - POCTI/EME/45573/200

    Finite element analysis of the ECT test on mode III interlaminar fracture of carbon-epoxy composite laminates

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    In this work a parametric study of the Edge Crack Torsion (ECT) specimen was performed in order to maximize the mode III component (GIII) of the strain energy release rate for carbon-epoxy laminates. A three-dimensional finite element analysis of the ECT test was conducted considering a [90/0/(+45/-45)2/(-45/+45)2/0/90]S lay-up. The main objective was to define an adequate geometry to obtain an almost pure mode III at crack front. The geometrical parameters studied were specimen dimensions, distance between pins and size of the initial crack. The numerical results demonstrated that the ratio between the specimen length and the initial crack length had a significant effect on the strain energy release rate distributions. In almost all of the tested configurations, a mode II component occurred near the edges but it did not interfere significantly with the dominant mode III state.FCT - POCTI/EME/45573/200

    Impacto de agrotoxicos utilizados na cultura do tomateiro a adultos de Trichogramma pretiosum Riley (Hym.: Trichogrammatidae)

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    O presente trabalho objetivou avaliar o impacto de (g. i. a. L de ågua)Bacillus thuringiensis (0.05), Chlorantraniliprole (0.04), Etifenoprox (0.13), Fenpropathrin (0.45), Triflumuron (0.144), Azoxystrobin (0.15), Diphenconazole (0.125), tebuconazole (0.2), fluazitop-p-butil (2.5) e metribuzin (2.4) recomendados para o controle de pragas (insetos, doenças e plantas daninhas na cultura do tomateiro.Resumo

    Unitary transformation approach for the trapped ion dynamics

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    We present a way of treating the problem of the interaction of a single trapped ion with laser beams based on successive aplications of unitary transformations onto the Hamiltonian. This allows the diagonalization of the Hamiltonian, by means of recursive relations, without performing the Lamb-Dicke approximation.Comment: 8 page

    RecomendaçÔes técnicas para o manejo integrado de pragas na cultura do alho.

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    Esta publicacão tem por finalidade apresentar uma descrição das pragas mais comumente encontradas na cultura do alho e dos danos causados a cultura no Brasil, bem como das técnicas usadas em seu monitoramentoe dos metódos de manejobitstream/item/81879/1/ct-118.pd

    Manejo da resistĂȘncia da mosca-branca Bemesia tabaci biĂłtipo B (Hemiptera: Aleyrodidae) a agrotĂłxicos utilizados em hortaliças.

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