Análise comparativa da quantificação da acção da neve de acordo com o RSA, a norma espanhola NBE e o EC1

A quantificação da acção da neve de acordo com a regulamentação em vigor em Portugal, Espanha e com o estabelecido no Eurocódigo 1 fornece resultados muito distintos. Neste trabalho é realizada uma análise comparativa entre o método de cálculo indicado pelo Regulamento de Segurança e Acções para Estruturas de Edifícios e Pontes, a norma espanhola NBE e o Eurocódigo 1. Foram analisados e comparados os vários parâmetros intervenientes na quantificação da acção da neve

Comparison of solar radio and EUV synoptic limb charts during the present solar maximum

The present solar cycle is particular in many aspects: it had a delayed rising phase, it is the weakest of the last 100 years, and it presents two peaks separated by more than one year. To understand the impact of these characteristics on the solar chromosphere and coronal dynamics, images from a wide wavelength range are needed. In this work we use the 17~GHz radio continuum, formed in the upper chromosphere and the EUV lines 304 and 171~{\AA}, that come from the transition region (He II) and the corona (Fe IX, X), respectively. We analyze daily images at 304 and 171~{\AA} obtained by the Atmospheric Imaging Assembly (AIA). The 17~GHz maps were obtained by the Nobeyama Radioheliograph (NoRH). To construct synoptic limb charts, we calculated the mean emission of delimited limb areas with 100" wide and angular separation of $5^\circ$. At the equatorial region, the results show an hemispheric asymmetry of the solar activity. The northern hemisphere dominance is coincident with the first sunspot number peak, whereas the second peak occurs concurrently with the increase in the activity at the south. The polar emission reflects the presence of coronal holes at both EUV wavelengths, moreover, the 17~GHz polar brightenings can be associated with the coronal holes. Until 2013, both EUV coronal holes and radio polar brightenings were more predominant at the south pole. Since then they have not been apparent in the north, but thus appear in the beginning of 2015 in the south as observed in the synoptic charts. This work strengthens the association between coronal holes and the 17~GHz polar brightenings as it is evident in the synoptic limb charts, in agreement with previous case study papers. The enhancement of the radio brightness in coronal holes is explained by the presence of bright patches closely associated with the presence of intense unipolar magnetic fields.Comment: 6 pages, 5 figures. Acccepted for publication in Astronomy & Astrophysic

Determinação eletroanalítica do pesticida paration metílico em eletrodo de carbono vítreo.

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Sodium dodecyl sulfate allows the persistence and recovery of biofilms of Pseudomonas fluorescens formed under different hydrodynamic conditions

The effect of the anionic surfactant sodium dodecyl sulfate (SDS) on Pseudomonas fluorescens biofilms was investigated using flow cell reactors with stainless steel substrata, under turbulent (Re=5200) and laminar (Re=2000) flow. Steady-state biofilms were exposed to SDS in single doses (0.5, 1, 3 and 7 mM) and biofilm respiratory activity and mass measured at 0, 3, 7 and 12 h after the SDS application. The effect of SDS on biofilm mechanical stability was assessed using a rotating bioreactor. Whilst high concentrations (7 mM) of SDS promoted significant biofilm inactivation, it did not significantly reduce biofouling. Turbulent and laminar flow-generated biofilms had comparable susceptibility to SDS application. Following SDS exposure, biofilms rapidly recovered over the following 12 h, achieving higher respiratory activity values than before treatment. This phenomenon of posttreatment recovery was more pronounced for turbulent flow-generated biofilms, with an increase in SDS concentration. The mechanical stability of the biofilms increased with surfactant application, except for SDS concentrations near the critical micellar concentration, as measured by biofilm removal due to an increase in external shear stress forces. The data suggest that although SDS exerts antimicrobial action against P. fluorescens biofilms, even if only partial and reversible, it had only limited antifouling efficacy, increasing biofilm mechanical stability at low concentrations and allowing significant and rapid recovery of turbulent flow-generated biofilms.Fundação para a Ciência e a Tecnologia (FCT

Gas proportional scintillation counter pulse-signature analysis using digital techniques

The use of short shaping time-constants (50 ns) followed by digital sampling of gas proportional scintillation counter pulses is investigated. Such short shaping time causes each pulse to closely resemble the scintillation light burst, allowing for an effective pulse-signature analysis. Pulse amplitude is obtained by numerical integration of the digital pulse samples. The shorter total pulse durations, lead to pulse-height distributions that are much less dependent on the total interaction rate occurring in the detector. Total interaction rates up to 12 k s-1 can be tolerated without significant degradation of the obtained pulse-height distribution. It was also verified that the maximum throughput achieved by the digital pulse-height analyser improves from 1 to 1.7 k s-1 when using the short shaping time-constants.http://www.sciencedirect.com/science/article/B6TJM-3VR1CVW-2F/1/2e9e952e1c3752048a2954b0dbbdec2

Thermal performance of lightweight steel framed wall: the importance of flanking thermal losses

"First Published August 21, 2013"The thermal performance of a modular lightweight steel framed wall was measured and calculated with three-dimensional finite element method model. The focus of this article is on the effect of flanking thermal losses. The calculated heat flux values varied from ?22% (external surface) to +50% (internal surface) when flanking loss was set to 0 as a reference case, thermal transmittance equal to 0.30 W/(m2·K). Other critical parameters were the existence of fixing ?L?-shaped steel elements and the perimeter thermal insulation (10 cm XPS).The authors would like to thank the European Union for funding in the form of the QREN SI I&DT N. 5527 – ‘CoolHaven – Development of residential modular and eco-sustainable houses, with structural light steel frames’ grant.info:eu-repo/semantics/publishedVersio

Using a glass-fibre reinforced polymer composite in the production of sustainable water storage vessels

The quest for sustainability by rethinking materials, products and production strategies is an enormous challenge currently laid upon the economic sector. Materials selection plays a critical role in this challenge. The present work describes a technological, environmental and economic study of the production of a water storage glass-fibre reinforced composite vessel. The vessel was evaluated via a Life Cycle Assessment/Life Cycle Costing (LCA/LCC) integrated model. The most significant life cycle phase was found to be the raw materials production, in which the Fossil fuels, Respiratory inorganics and Climate change were the relevant impact categories. The vessel environmental and economic performances could be improved if an end of life (EoL) option different from landfill had been chosen. The present work describes a new integrated way of analysing the environmental and economic performances of a structural product full life cycle. It also highlights the role and importance of fibre reinforced polymer composites in the quest for sustainable products.FCT projeto SFRH/BD/60852/2009 e IPC projeto UID/CTM/50025/201