Artigos de Revista
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Ureasilicate Hybrid Coatings for Corrosion Protection of Galvanized Steel in Cementitious Media
This study is focused on the electrochemical behavior and surface analysis of an eco-friendly organicinorganic hybrid (OIH) coating for hot dip galvanized steel (HDGS) in contact with cementitious media. This treatment is a proposed alternative to replace toxic Cr(VI)-based pre-treatments used to control reactions between the zinc and wet concrete. HDGS samples were coated with two different sets of OIH gels obtained by a sol-gel process using a dip-coating method. Five distinct OIH matrices were obtained by reaction of functionalized metal-alkoxide (3-isocyanatopropyltriethoxysilane) with five different molecular weight diamine-alkylethers. One set of HDGS samples was coated with each of the five pure OIH matrices and another was coated with similar matrices doped with Cr(III). The morphology of OIH coatings over HDGS surface was characterized by SEM/EDS. Similar films were prepared separately and the respective resistivity was measured by electrochemical impedance spectroscopy. Polarization resistance and macrocell current density were used to evaluate the corrosion protection properties of the HDGS coated samples in contact with cementitious media for a period of 74 days. Results showed that the produced coatings provide barrier properties that withstand the high pH of the electrolyte, protecting the HDGS when it first contacts cementitious media.
Ano: 2013
Número Páginas:
12.
Autor(es): Figueira, R. B.; Silva, C. J. R.; Pereira, E. V.; Salta, M. M.
Revista: Journal of the Electrochemical Society
Editor: Journal of the Electrochemical Society
Volume:
volume 160, issue 10, C467-C479.
Keywords: Coatings; Corrosion; Organic-inorganic hybrid; Sol-gel; Galvanized steel
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Use of the velocity defect law to assess sand transport rates
This work uses a simple method based on the defect law that is able to reproduce the horizontal velocities within the wave bottom boundary layer, using a limited number of parameters. The theory is checked against the measured velocity profiles gathered with a high resolution Acoustic Doppler Velocity Profiler. The velocities were collected during an experimental project performed at the Large Oscillating Water Tunnel of Deltares under flat-bed/sheet flow conditions, allowing the analysis of the effects of wave nonlinearities and of a net current on the sediment transport processes. The velocity estimates are used to infer the time-varying bed shear stress, using the momentum-integral method. Secondly, the bed shear stresses are incorporated in a quasi-steady bed load formulation and the transport rate predictions are compared with the net transport rate measurements obtained in the same facility. The results show that the methodology presented in this work provides a suitable estimation of the horizontal near-bed sediment transport rates under non-linear oscillatory flows.
Ano: 2013
Número Páginas:
1485-1490pp.
Autor(es): Abreu, T.; Silva, P. A.; Sancho, F. E.; Michallet, H.
Revista: Journal of Coastal Research
Editor: Journal of Coastal Research
Keywords: Sheet-flow; Defect law; Sand transport; Bed shear stress; Horizontal velocities; Oscillatory flows
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Using Visual Methodologies to Understand the Urban Cultural Landscape
This reflection explores the advantages of using visual methodologies to understand the urban cultural landscape, focusing on the use and appropriation of public space by immigrants. We based this discussion on an exploratory study developed for the Praça República in Ericeira, within the Metropolitan Area of Lisbon, that identified specific characteristics of the use and appropriation of urban public space by Brazilian immigrants. It identifies five advantages arising from the use of visual methodologies: (1) the process of collection and registration of information; (2) multiple possibilities of articulation between the visual techniques of observation and analysis and the interpretation techniques for other information collected; (3) enhancing inter/multidisciplinary potential through the working methodologies; (4) improving the capacity to respond to urban social diversity and complexity; (5) the potential for mapping the social practices of immigrants.
Ano: 2013
Número Páginas:
125-144 p..
Autor(es): Menezes, M.; Allen, J.; Vasconcelos, L.
Revista: Revista Lusófona de Arquitectura e Educação /Architecture & Education Journal
Editor: Laboratório de Arquitectura / Architectural (LabART)
Volume:
6-7 (2012).
Keywords: Visual methodologies; Cultural landscape; Immigrants; Urban public space; Use and appropriation
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Ventilação de edifícios de habitação: Qualidade do ar interior e eficiência energética
Princípios gerais da proposta para a revisão do RCCTE
Ano: 2013
Número Páginas:
68-75pp.
Autor(es): Pinto, A.
Revista: Edifícios e Energia
Editor: Media Line, Lda.
Volume:
n.º 85.
Keywords: Eficiência energética; Qualidade do ar interior; Edifícios de habitação; Ventilação
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Viabilidade Técnica e impacto económico da aplicação do método Bootstrap em estudos de repetibilidade e reprodutividade
A repetibilidade e a reprodutibilidade são duas caracteristicas metrológicas que, frequentemente, constituem relevantes contribuições para a incerteza de medição associada aos resultados de ensaios laboratoriais realizados em contexto industrial e técnico-cientifico. A sua quantificação permite uma análise diferenciada e combinada do efeito que os principais fatores intervenientes no processo de medição (designadamente, a instrumentação, o método e o operador) têm na qualidade dos resultados, promovendo a melhoria da qualidade dos processos laboratoriais e industriais e, por essa via, constituir uma ferramenta de apoio para a garantia da qualidade de produtos e serviços. Numa fase inicial, a presente comunicação pretende clarificar a definição destes dois conceitos [1] abordando-se, em seguida, o dimensionamento de ensaios laboratoriais de repetibilidade e reprodutibilidade, comparando a aplicação de métodos estatísticos clássicos (por exemplo, o método ANOVA) [2,3] com a exploração do método de simUlação numérica Bootstrap [4]. procurando avaliar a capacidade destes métodos para garantir resultados com elevado nível de confiança e para reduzir os custos económicos para os laboratórios decorrentes da necessidade de se promover este tipo de ensaios. A aplicação dos métodos acima mencionados é exemplificada em ensaios laboratoriais de medição dimensional sendo efetuada uma comparação de resultados experimentais, suportando a discussão da aplicação da abordagem alternativa constituída pela utilização de método de simulação numérica neste e noutros contextos onde a informação resulta essencialmente das amostras experimentais, como é o caso dos ensaios de comparação interlaboratorial.
Ano: 2013
Número Páginas:
19-29pp.
Autor(es): Lages Martins, L.; Ribeiro, A.
Revista: Revista Medições e Ensaios
Editor: SPMet - Sociedade Portuguesa de Metrologia
Volume:
N.º 5.
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Wave Runup and Overtopping at Seawalls Built on Land and in Very Shallow Water
The current study proposes prediction formulas both for random wave runup and mean overtopping discharge at seawalls constructedon land or in very shallow water. Although several existing formulas for runup and overtopping use the incident wave characteristicsat the toes of seawalls, this study adopts the equivalent deepwater wave characteristics and an imaginary seawall slope for easy application of theformulas, especially in relation to seawalls constructed on land. The prediction formulas for overtopping use the predicted runup values. For thewave runup prediction formulas two sets of experimental data are used; i.e., a new set of data and the data obtained in a previous study. For thewave overtopping prediction formulas, the experimental data measured in a previous study are used. Comparisons with measurements showgood performances of both new prediction methods.
Ano: 2013
Número Páginas:
346-357pp.
Autor(es): Mase, H.; Tamada, T.; Yasuda, T.; Hedges, T.; Reis, M. T.
Revista: JOURNAL OF WATERWAY, PORT, COASTAL, AND OCEAN ENGINEERING
Volume:
Vol. 139(5).
Keywords: Imaginary seawall slope; Seawalls near shoreline; Wave overtopping; Wave runup
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Wave-current interactions in a wave-dominated tidal inlet
Wave-current interactions play a major role in the dynamics of shallow tidal inlets. Thisstudy investigates these interactions at a natural inlet, with a strong focus on current-inducedchanges on wave propagation. The analysis of hydrodynamic data collected at the Albufeiralagoon, Portugal, revealed spatiotemporal variations of water levels and wave heights alongthe inlet, attributed to wave-current interaction processes. We compared the simulations of acoupled wave-circulation modeling system, computed with and without waves, andpropagated with and without current feedback. The wave-induced setup inside the lagoonrepresented 7%
Ano: 2013
Número Páginas:
1587-1605pp.
Autor(es): Dodet, G.; Bertin, X.; Bruneau, N.; Fortunato, A. B.; Nahon, A.; Roland, A.
Revista: JOURNAL OF GEOPHYSICAL RESEARCH: OCEANS
Editor: JOURNAL OF GEOPHYSICAL RESEARCH: OCEANS
Volume:
Volume 118.
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3D stability analysis of gravity dams on sloped rock foundations using the limit equilibrium method
A convenient approach to performing stability analysis of concrete gravity dams is the so-called twodimensional
Ano: 2012
Número Páginas:
147-156pp.
Autor(es): Bretas, E. M.; Leger , P.; Lemos, J. V.
Revista: Computers and Geotechnics
Editor: Elsevier
Volume:
44.
Keywords: Sloped rock foundation; Limit equilibrium; Sliding; Concrete gravity dam
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A comparative study on the thermo-oxidative stability of polyethylene
The main goal of this work is to establish a correlation between the oxidation induction time (OIT) and the oxidation induction temperature (OIT*), which are frequently used to assess the thermo-oxidative stability of polyolefins, either as raw-materials or as finished products. Several tests have been performed at different temperatures (200, 210 and 220 C) using a set of polyethylene (PE) samples from different sources. The correlations found - based on a quadratic regression make it possible to estimate the OIT value based on experimental data of OIT* and vice-versa. This method can be quite useful in cases when the PE is highly stabilized so that the OIT test at 200 C is expected to last for hours. Additionally, an Arrhenius plot has been developed to obtain the activation energy (Ea) associated with the beginning of the thermo-oxidation for each PE, which also allows us to determine OIT from calculated Ea. All estimated values, obtained by the developed regression models, using unknown specimens, have been confirmed by experimental testing. The regression models have also been checked by a residual analysis as a way to evaluate their reliability. The contribution of the uncertainties of measurement and calculation has also been evaluated, leading to increased reliability of the findings.
Ano: 2012
Número Páginas:
963-969.
Autor(es): Real, L. P.
Revista: Polymer Testing
Editor: Elsevier
Volume:
31.
Keywords: Oxidation induction time/temperature; Thermoxidation; Differential scanning calorimetry; Polyethylene
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A comparision in the evaluation of measurement uncertainty in analytical chemistry testing between the use of quality control data and a regression analysis
N/A
Ano: 2012
Número Páginas:
8p.
Autor(es): Sousa, J. A.; Reynolds, A. M.; Ribeiro, A.
Revista: Accreditation and Quality Assurance - Journal for Quality, Comparability and Reliability in Chemical Measurement
Editor: Springer
Keywords: Gum uncertainty framework; Monte carlo method; Regression analysis; Chemical metrology; Measurement uncertainty
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