Flexure of continuous HSC beams with external CFRP tendons: effects of fibre elastic modulus and steel ratio

The results of a theoretical study on the flexural behaviour of continuous high-strength concrete (HSC) beams prestressed with external fibre reinforced polymer (FRP) tendons are presented. A previously developed numerical model is extended to the analysis of continuous HSC beams with external FRP tendons. A numerical test is conducted on two-span externally prestressed beams made of HSC with compressive strength of 90 MPa. The external tendons are assumed to be carbon FRP (CFRP) composites covering a wide range of modulus of elasticity. Various levels of nonprestressed steel ratio are used. Comprehensive aspects of behaviour of such type of beams are examined. The results show that CFRP with high elastic modulus of 500 GPa mobilizes quite different structural responses compared to those with normal elastic modulus, and that the amount of nonprestressed steel affects remarkably the behaviour of such beams. The study also indicates that some moment redistribution knowledge valid for conventional continuous concrete beams may not be applicable to continuous HSC beams with external FRP tendons

Development of liquid xenon detectors for medical imaging

In the present paper, we report on our developments of liquid xenon detectors for medical imaging, positron emission tomography and single photon imaging, in particular. The results of the studies of several photon detectors (photomultiplier tubes and large area avalanche photodiode) suitable for detection of xenon scintillation are also briefly described.Comment: 13 pages, 5 figures, presented on the International Workshop on Techniques and Applications of Xenon Detectors (Xenon01), ICRR, Univ. of Tokyo, Kashiwa, Japan, December 3-4, 2001 (submitted to proceedings

Factors affecting moment redistribution at ultimate in continuous beams prestressed with external CFRP tendons

A numerical investigation of redistribution of moments in continuous concrete beams prestressed with external carbon fiber reinforced polymer (CFRP) tendons at failure loads is described. A finite element analysis (FEA) model is introduced, and an extensive parametric study is carried out on two-span continuous beams. The factors examined in this study include the content of non-prestressed steel, tendon eccentricities, tendon area, effective prestress, span-to-height ratio, concrete strength, CFRP modulus of elasticity and load type. The results obtained from FEA are compared with those obtained from various codes. The study shows that the importance of some factors is not reflected in the codes. When used to calculate the degree of moment redistribution in these beams, the parameter εt (net strain in extreme tension steel) seems to be more reasonable than the parameter c/d (ratio of neutral axis depth to section effective depth). A simplified equation for calculating the degree of moment redistribution at ultimate is proposed

CNA 8170: linhagem de arroz adaptada para o ecossistema terra firme do Estado do Pará.

Cópia de trabalho editado em CD-ROM

Produção de cachos e parâmetros genéticos de híbridos de caiaué com dendezeiro.

O objetivo deste trabalho foi avaliar a produção de cachos e estimar os parâmetros genéticos de progênies F1 de caiaué (Elaeis oleifera) com dendezeiro (E. guineenses). As progênies foram plantadas em parcelas com número variável de plantas. Avaliaram-se número (NC), peso médio (PMC) e peso total de cachos (PTC), por planta, do sétimo ao décimo?terceiro ano após o plantio. Estes dados foram analisados por REML/BLUP em 59 progênies, com delineamento desbalanceado em linha e coluna. Todos os caracteres apresentaram considerável variabilidade, com coeficientes de variação genética entre 18,1 e 25,5%, quanto à progênie, e de 25,6 a 36,0% quanto a indivíduo. Pela seleção das cinco melhores progênies, podem ser obtidos ganhos superiores a 30%, para NC e PTC, e acima de 20% para PMC; e, com a seleção dos cinco melhores indivíduos, ganhos acima de 65%, para NC e PTC, e acima de 60% para PMC. As progênies apresentam alta variabilidade genética quanto à produção de cachos. Ganhos genéticos elevados podem ser obtidos pela seleção tanto de indivíduos para clonagem quanto de progênies para reprodução sexuada

Maravilha: cultivar de arroz de sequeiro recomendada para a região oeste do Estado do Pará.

bitstream/item/28026/1/com.tec.74.pd

Ensaio comparativo avançado de arroz de sequeiro em Alenquer, Pará - ano agrícola 1998/1999.

bitstream/item/52946/1/PesquisaAnd0170001.pd

Localized states at zigzag edges of bilayer graphene

We report the existence of zero energy surface states localized at zigzag edges of bilayer graphene. Working within the tight-binding approximation we derive the analytic solution for the wavefunctions of these peculiar surface states. It is shown that zero energy edge states in bilayer graphene can be divided into two families: (i) states living only on a single plane, equivalent to surface states in monolayer graphene; (ii) states with finite amplitude over the two layers, with an enhanced penetration into the bulk. The bulk and surface (edge) electronic structure of bilayer graphene nanoribbons is also studied, both in the absence and in the presence of a bias voltage between planes.Comment: 4 pages, 5 figure