Artigos de Revista
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3D survey modelling for damage assessment in rubble-mound breakwaters under oblique wave incidence
Several authors have proposed guidelines on how to consider the effects of oblique waves on the stability of armour layers of rubble-mound breakwaters. Especially for very oblique waves, for which the increase in stability is the largest, limited data are available. Under the scope of the HYDRALAB+ transnational access project RODBreak, experiments were conducted in a tank at the Marienwerder facilities of the Leibnitz University Hannover (LUH), comprising measurements of sea waves, runup, overtopping and armour layer damage of a rubble-mound breakwater under oblique extreme wave conditions. This paper focuses on the analysis of damage evolution of the breakwater roundhead subject to these conditions, on the novelty of the nonintrusive survey methodologies and on the advance in knowledge on roundhead stability.
Ano: 2020
Número Páginas:
73-85pp.
Autor(es): Lemos, R.; Peña, E.; Santos, J. A.; Sande, J.; Figuero, A.; Alvarellos, A.; Laiño, E.; Reis, M. T. L. G. V.; Fortes, C. J. E. M.; Kerpen, N.B.; Coelho, R.
Revista: Italian Journal of Engineering Geology and Environment
Editor: Sapienza Università Editrice
Volume:
1 (2020).
Keywords: Large scale experiments; Measuring techniques; Surveying; Stability; Coastal structure
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A Discrete Element Model for Masonry Vaults Strengthened with Externally Bonded Reinforcement
The paper investigates the effectiveness of two-dimensional Discrete Element Method as a tool for structural analysis of arches provided with buttresses and backfill and strengthened with externally bonded reinforcement. Masonry vault and buttresses are modelled as an assembly of 2D rigid blocks interacting through non-linear contact joints, the backfill is discretized into deformable elastic-plastic triangular elements, while the reinforcement is modelled by means of truss elements bonded to the substrate through non-linear springs. A parametric analysis on the influence of material parameters and the effect of the discretization of the backfill is carried out, and the outcome of different reinforcement systems, consisting of Steel Reinforced Grout applied either at the intrados or at the extrados, are analysed. The comparison with experimental full-scale tests proved the ability of the numerical approach to capture hinges position, load bearing capability, as well as the increase in deflection and load capacity provided by the reinforcement.
Ano: 2020
Autor(es): Gobbin, F.; De Felice, G.; Lemos, J. V.
Revista: International Journal of Architectural Heritage
Editor: Taylor & Francis
Keywords: Discrete Element Method; masonry; numerical modelling; Steel Reinforced Grout
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A methodology for the evaluation of evolution and risk of breakwaters. Application to Portimão harbor and of Faro-Olhão inlet
This paper describes a program under the responsibility of LNEC for the systematic observation and monitoring of maritime works that has successfully been applied to a number of maritime structures on the Portuguese mainland coast. The now-called OSOM+ program comprises the following four main components for each structure: i) periodic visual inspections by an experienced technician; ii) periodic aerial inspections with a UAV/ drone; iii) a ANOSOM-WEB database, to store and/or query obtained information on the observation campaigns, as well as to diagnose present, evolution and risk conditions of the structure; iv) a mobile, portable, application, for realtime input and visualization of the database information. OSOM+ has recently been updated with a number of tools and functionalities that are illustrated in this paper with applications to two real case studies: the Portimão harbor breakwaters and Faro-Olhão inlet entrance breakwaters, both located in the south coast of Portugal.
Ano: 2020
Autor(es): Lemos, R.; Capitão, R.; Fortes, C. J. E. M.; Henriques, M. J.; Silva, L. G.; Martins, T.
Revista: Revista de Gestão Costeira Integrada
Editor: APRH
Volume:
20(2).
Keywords: Risk assessment; Harbour; Inlet; Breakwater
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An assessment of contact and laser-based scanning of rock particles for railway ballast
Performance of traditional railway structure depends significantly on the behaviour of its support layers, particularly the ballast. This layers rock particles are selected to ensure high mechanical strength, but traffic and mechanical maintenance break and wear the particles. Consequently, the layer incurs permanent deformations that degrade its strength and increase deformability and permeability. Particle physical characteristics, in particular those related to size and shape, influence their fragmentation and wear and must be studied accordingly. In addition, structural numerical models that represent individual particles, such as the discrete element method, have been increasingly used to model the infrastructure and therefore detailed geometrical characterization in the form of 3D digital models of the particles are necessary. This work contributes to this goal by investigating a contact-based cost-effective method that digitizes particle form and allows the determination of their geometric parameters. This method is described, compared with well- established laser scanning technique and then applied to study degradation of particles in Los Angeles and microDeval fragmentation tests.
Ano: 2020
Número Páginas:
100302.
Autor(es): Jerónimo, P.; Resende, R.; Fortunato, E.
Revista: Transportation Geotechnics
Editor: Elsevier
Volume:
22.
Keywords: Rock breakage; Contact scanning; Laser; 3D scanning; Particle shape; Railway ballast
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Aspetos gerais da aplicação em Portugal do Eurocódigo 8 Parte 3 Anexo C (Informativo) Edifícios de alvenaria
Procuram-se sintetizar neste artigo os principais aspetos relacionados com a avaliação e a reabilitação sísmica de edifícios existentes de alvenaria, compatibilizando a NP EN 1998-3:2017 com os respetivos Anexo C, específico para edifícios de alvenaria, e Anexo Nacional, específico para Portugal. A avaliação sísmica é um procedimento quantitativo através do qual se verifica se um edifício existente, danificado ou não, satisfaz os requisitos de desempenho, definidos por uma combinação de um estado limite com um nível de ação sísmica, através de critérios de conformidade. Neste procedimento estão envolvidos a definição da ação sísmica, a modelação da estrutura, os métodos de análise para determinação dos efeitos das ações e as verificações de segurança. São abordados os métodos de análise, dois lineares e dois não lineares, aplicáveis a edifícios existentes de alvenaria, bem como as recomendações específicas do Anexo C e as informações complementares do Anexo Nacional.
Ano: 2020
Número Páginas:
99-120pp.
Autor(es): Candeias, P.; Correia, A.A.; Campos Costa, A.; Catarino, J. M.; Pipa, M.; Cruz, H.; Cansado Carvalho, E.; Costa, A.
Revista: Revista Portuguesa de Engenharia de Estruturas (rpee)
Editor: LNEC
Volume:
Série III, N.º 12.
Keywords: Eurocódigo 8; Avaliação sísmica; Edifícios de alvenaria existentes
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Assessing the applicability of a new carob waste-derived powdered activated carbon to control pharmaceutical compounds in wastewater treatment.
This paper assesses the applicability of a new carob waste-derived powdered activated carbon (PAC) obtained by steam activation for pharmaceutical compounds (PhCs) removal in urban wastewater treatment plants (WWTPs) with activated sludge (AS) secondary treatment. The new carob-derived PAC presents chemical and textural properties similar to a high-performing commercial PAC produced from vegetable source by physical activation. The adsorption isotherms of three target PhCs, carbamazepine, diclofenac and sulfamethoxazole, spiked (at around 100 ?g/L) in mixed liquor (ML) and in clarified-ML from the AS-bioreactor of a WWTP show: (i) minor reduction of PAC capacity with real MLs compared to clarified MLs; (ii) the higher the PhC hydrophobicity, the higher the PAC adsorption capacity in both water matrices; (iii) hydrophobic interactions probably overweight electrostatic interactions between the PhCs and the slightly positively charged PAC in these real water matrices with background organics and inorganics. The PhC adsorption results with ML and clarified-ML are used to calibrate the IAST-based tracer model (TRM) and predict the new PAC performance when added to AS-bioreactor vs. in post-secondary treatment, at the PhC naturally-occurring trace concentrations. The modelling projections show (i) one needs higher PAC doses than those reported in the literature, particularly in post-treatment, and (ii) the benefits of PAC dosing to the bioreactor, with only a slightly higher PAC dose being needed when compared to its post-secondary dosing and minimising the capital investment.
Ano: 2020
Número Páginas:
10 pp..
Autor(es): Viegas, R.M. C.; Mestre, A.S.; Mesquita, E.; Campinas, M.; Andrade, M. A.; Carvalho, A. P.; Rosa, M. J.
Revista: Science of The Total Environment
Editor: Elsevier
Volume:
Volume 743.
Keywords: Modelling; Pharmaceutical compounds; Adsorption; Steam activation; Waste-derived activated carbons
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Assessment of CFD Solvers and Turbulent Models for Water Free Jets in Spillways
The capability of two different OpenFOAM® solvers, namely interFoam and twoPhaseEulerFoam, in reproducing the behavior of a free water jet was investigated. Numerical simulations were performed in order to obtain the velocity and air concentration profiles along the jet. The turbulence intensity was also analyzed. The obtained results were compared with published experimental data and, in general, similar velocity and air concentration profiles were found. InterFoam solver is able to reproduce the velocity field of the free jet but has limitations in the simulation of the air concentration. TwoPhaseEulerFoam performs better in reproducing the air concentration along the jet, the results being in agreement with the experimental data, although the computational runs are less stable and more time consuming. The sensitivity analysis of the inlet turbulent intensity showed that it has no influence in the characteristics of the jet core. With this research it is possible to conclude that: interFoam with k-Epsilon (k-?) turbulence model is the best choice if the goal of the numerical simulations is the simulation of the velocity field of the jet. Meanwhile, twoPhaseEulerFoam with mixturek-Epsilon (mk-?) shall be considered if the objective is the simulation of the velocity field and the air concentration.
Ano: 2020
Número Páginas:
17pp.
Autor(es): Muralha, A.; Melo, J.; Ramos, H.
Revista: Fluids
Editor: MDPI
Volume:
V5, 104.
Keywords: Spillways; Turbulence models; Waterair flow; CFD solvers; Free water jet
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Atenolol removal by nanofiltration: a case-specific mass transfer correlation
Concentration polarization is a phenomenon inherent to membrane separation operations and as a precursor of membrane fouling is frequently related to the decrease in the performance of these operations. In the present work, a case-specific mass transfer correlation was developed to assess the concentration polarization when nanofiltration, in different operating conditions, was applied to treat a pharmaceutical wastewater containing atenolol. NF runs with two membranes, two atenolol concentrations and three feed circulating velocities were conducted, and the corresponding experimental mass transfer coefficients were determined using film theory to describe the concentration polarization phenomenon. Higher velocities led to higher mass transfer coefficients and, consequently, lower concentration polarization. These mass transfer coefficients were correlated with the circulating velocity (Re), the solute diffusivity (Sc) and the membrane permeability (LPþ) (the membrane is a permeable interface with effect on the concentration profiles developed from the interface towards the bulk feed), yielding the following correlation Sh ¼ 1.98 × 104Re0.5Sc0.33LP þ0.32. The good agreement between the calculated and the experimental results makes this correlation a valuable tool for water practitioners to predict and control the concentration polarization during atenolol-rich wastewater treatment by nanofiltration, thereby increasing its productivity and selectivity.
Ano: 2020
Número Páginas:
7 pp..
Autor(es): Giacobbo, A.; Fernandes, E.; Bernardes, A.M.; Rosa, M. J.; Pinho, M.N.
Revista: Water Science & Technology
Editor: IWA Publishing
Volume:
Vol. 81.2.
Keywords: Nanofiltration; Mass transfer; Concentration polarization; Atenolol
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Atenolol removal by nanofiltration: a case-specific mass transfer correlation.
Concentration polarization is a phenomenon inherent to membrane separation operations and as a precursor of membrane fouling is frequently related to the decrease in the performance of these operations. In the present work, a case-specific mass transfer correlation was developed to assess the concentration polarization when nanofiltration, in different operating conditions, was applied to treat a pharmaceutical wastewater containing atenolol. NF runs with two membranes, two atenolol concentrations and three feed circulating velocities were conducted, and the corresponding experimental mass transfer coefficients were determined using film theory to describe the concentration polarization phenomenon. Higher velocities led to higher mass transfer coefficients and, consequently, lower concentration polarization. These mass transfer coefficients were correlated with the circulating velocity (Re), the solute diffusivity (Sc) and the membrane permeability (LP+) (the membrane is a permeable interface with effect on the concentration profiles developed from the interface towards the bulk feed), yielding the following correlation Sh = 1.98 × 104Re0.5Sc0.33LP+0.32. The good agreement between the calculated and the experimental results makes this correlation a valuable tool for water practitioners to predict and control the concentration polarization during atenolol-rich wastewater treatment by nanofiltration, thereby increasing its productivity and selectivity.
Ano: 2020
Número Páginas:
7 pp..
Autor(es): Giacobbo, A.; Bernardes, A.M.; Rosa, M. J.; Pinho, M.N.
Revista: WATER SCIENCE & TECHNOLOGY
Editor: IWA Publishing
Volume:
Volume 81, Issue 2.
Keywords: Nanofiltration; Mass transfer; Concentration polarization; Atenolol
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Benefícios e desafios na cocriação de espaço público aberto com apoio das ferramentas digitais. As experiências dos Projetos CyberParks e C3Places
As tecnologias de informação e comunicação (TIC) podem ser ferramentas inovadoras para a interação com e entre os utilizadores do espaço público. Por um lado, as ferramentas digitais (smartphones, relógios inteligentes, tablets, portáteis, etc.) colaboram para intermediar a criação de contextos socio-espaciais interativos; por outro, as TIC podem ser consideradas como recurso instigador de processos de planeamento mais colaborativos e participativos. O artigo discute alguns benefícios e desafios que as TIC apresentam no âmbito do aperfeiçoar o conhecimento sobre a relação entre espaço público aberto, pessoas e práticas sociais; e no que respeita à mediação e ao fomento de processos participativos na produção do espaço através do recurso às dinâmicas de cocriação. Para o desenvolvimento desta reflexão, realiza-se uma abordagem teórica e enquadradora a partir de perspetivas etnográficas e de planeamento e recorre-se ao conhecimento adquirido e experiências protagonizadas nos projetos CyberParks e C3Places.
Ano: 2020
Número Páginas:
27-36.
Autor(es): Menezes, M.; Costa, C.
Revista: Geotema - Rivista dell'Associazione Geografi Italian
Editor: AGEI
Volume:
62.
Keywords: perspetivas etnográficas e de planeamento urbano; co-criação na produção do espaço público; Espaço público aumentado/híbrido
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