5,051 research outputs found
A new data reduction scheme to obtain the mode II fracture properties of Pinus Pinaster wood
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
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
Combined effects of chemical dip and/or edible coating and/or controlled atmosphere on quality of fresh-cut banana
Cumulative incidence estimates in the presence of competing risks
This study was funded by FEDER through the Operational Program Competitiveness and Internationalization and national funding from the Foundation for Science and Technology—FCT (Portuguese Ministry of Science, Technology and Higher Education) under the Unidade de Investigação em Epidemiologia—Instituto de Saúde Pública da Universidade do Porto (EPIUnit) (POCI-01-0145-FEDER-006862; Ref. UID/DTP/04750/2013). An individual PhD grant attributed to S.M. (SFRH/BD/102585/2014) was funded by FCT and the “Programa Operacional Capital Humano” (POCH/FSE). The funding sources had no involvement in the conduct of the research and/or preparation of the commentary
Low-field microwave absorption and magnetoresistance in iron nanostructures grown by electrodeposition on n-type lightly-doped silicon substrates
In this study we investigate magnetic properties, surface morphology and
crystal structure in iron nanoclusters electrodeposited on lightly-doped (100)
n-type silicon substrates. Our goal is to investigate the spin injection and
detection in the Fe/Si lateral structures. The samples obtained under electric
percolation were characterized by magnetoresistive and magnetic resonance
measurements with cycling the sweeping applied field in order to understand the
spin dynamics in the as-produced samples. The observed hysteresis in the
magnetic resonance spectra, plus the presence of a broad peak in the
non-saturated regime confirming the low field microwave absorption (LFMA), were
correlated to the peaks and slopes found in the magnetoresistance curves. The
results suggest long range spin injection and detection in low resistive
silicon and the magnetic resonance technique is herein introduced as a
promising tool for analysis of electric contactless magnetoresistive samples.Comment: 12 pages, 5 figure
Composição quĂmica do Ăłleo essencial de duas amostras de carqueja coletadas em Paty do Alferes.
O Brasil possui em sua flora a maior diversidade genĂ©tica do mundo, apresentando diversas espĂ©cies nativas. Dentre as plantas nativas do Brasil encontra-se o gĂŞnero Baccharis (famĂlia Asteraceae) que possui algumas espĂ©cies popularmente conhecidas como carqueja, carqueja amarga ou vassoura. Estas espĂ©cies vem sendo utilizadas na medicina popular como protetora e estimulante do fĂgado, para o controle da obesidade, diabetes, hepatite, gastroenterite, digestiva, diurĂ©tica, depurativa, tĂ´nica, antianĂŞmica e anti-reumática. Este trabalho teve por objetivo investigar a composição quĂmica do Ăłleo essencial de duas populações do gĂŞnero Baccharis coletadas Paty do Alferes, visando encontrar novas fontes de carquejol e acetato de carquejila. Amostras de duas populações diferentes de carqueja foram coletadas em propriedades particulares Paty do Alferes - Rio de Janeiro em novembro de 2010. Estas foram secas a temperatura ambiente (28ÂşC +- 2) e Ă sombra. O Ăłleo essencial das duas amostras de Baccharis sp. foi extraĂdo por hidrodestilação em aparelho tipo Clevenger modificado por 4 horas. O mesmo foi analisado por cromatografia gasosa acoplada Ă espectrĂ´metro de massas (CG-EM Shimadzu, QP 5050, coluna capilar DB-5 - 30 m x 0.25mm x 0.25micrĂ´metro). Utilizou-se o Helio como gás carreador (1.7mL/min); temperatura do injetor: 240ÂşC e detector: 230ÂşC, Split: 1:20, no seguinte programa de temperatura: 60° C -- 240° C (3°C/ min). A identificação da composição quĂmica dos Ăłleos essenciais foi realizada pela comparação de seus espectros de massa e valores de Ăndice de Kovats (IK) com compostos conhecidos descritos na literatura. Foram encontrados 19 compostos nestes Ăłleos essenciais. Os principais compostos encontrados foram trans-cariofileno (22,0 % e 18,1%), seguido por germacreno-D (7,0%), biciclogermacreno (8,5%), ledol (13,7%), espatulenol (13,8% e 20,7%) e Ăłxido de cariofileno (8,3% e 12,0%). Carquejol e acetato de carquejila nĂŁo foram observados nestas amostras de Ăłleo essencial, o que pode ser um indicativo que esta espĂ©cie nĂŁo Ă© B. trimera. Estes resultados mostraram que estas amostras coletadas em Paty do Alferes apresentam composição quĂmica similar e podem ser a mesma espĂ©cie vegetal, com grande indicativo de ser B. crispa (B cylindrica)
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