5678 research outputs found
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The resource valuation and the challenge of coastal ecosystem-based management implementation
No full text1pDHA/NP
Adaptabilidade/flexibilidade e tipologia habitacional
No full textA adaptabilidade da habitação a diversos modos de vida e usos domésticos ou específicos, colocada ao serviço de diversos tipos de agregados familiares e de diversas apropriações funcionais e pormenorizadas, é cada vez mais um aspeto fundamental a considerar na conceção dos espaços domésticos, mediante a referência à opinião de diversos autores, que salientaram a importância de deixarmos de privilegiar organizações domésticas rígidas e excessivamente hierarquizadas, favorecendo-se, sim, os caminhos marcados por espaços habitacionais mais apropriáveis e potencialmente mutantes.3 fig7 pInfohabitar, Ano X, n.º 473DED/NUTRevista Infohabita
Study of zirconia and silica-zirconia-epoxy sol-gel coatings for corrosion protection of EN AW 6063 aluminium alloy
No full textCoating an aluminium alloy in building and automotive industries requires its surface pre-treatment to promote adherence of the organic coating. Chromate based chemical conversion layers (CCC) have been extensively used for that purpose since they not only provide very good adhesion of organic coatings, but also afford corrosion protection, both by barrier and self-healing effect. However, the use of these surface treatments has been under severe restrictions in the European Community due to Cr (VI) toxicity and carcinogenic effects. Within building industry, several “green” alternative inorganic treatments are already being applied, but they lack the anticorrosive action of the Cr(VI) compounds. Coating via the sol-gel process has been pointed out as a promising environmentally friendly alternative to chromate pre-treatments. This type of coatings, namely the organic-inorganic hybrid sol-gel silane based ones provide corrosion protection by barrier effect and when corrosion inhibitors are incorporated in their structure active protection is conferred as well. The sol-gel coating is also able to promote adherence between the metallic substrate and an organic top layer.
In this work, several organic-inorganic hybrid (IOH) sol-gel coatings with different organic content were synthesized from glycidoxypropyltrimethoxysilane (GPTMS) and zirconium n-propoxide (TPOZ) precursors by the sol-gel process. Cerium nitrate was added during synthesis to be incorporated in the final coating and act as corrosion inhibitor. The synthesized OIH coatings were applied on EN AW-6063 alloy by dip-coating. The corrosion protection performance of coatings was evaluated in chloride medium by means of Electrochemical Impedance Spectroscopy (EIS) and by Salt Spray Test (NSS). A solely inorganic zirconium based sol-gel coating was also prepared and tested for comparison. The chemical composition with depth was analysed by means of Glow Discharge Optical Emission Spectroscopy (GDOES) and the thickness of coatings was estimated based on elemental depth profiles. Finally the aluminium alloy coated samples were bent to evaluate coatings adhesion to the substrate. The morphology of the aluminium coated samples after corrosion and deformation tests was observed by scanning electron microscopy (SEM-EDS).
Electrochemical measurements provided evidence that the hybrid sol-gel coatings are much more corrosion protective than the solely inorganic ones. Additionally, it was observed that an increase in the organic content by the introduction of the epoxysilane in the coating formulation improves its corrosion resistance, but above a certain limit is detrimental to coating adherence, as shown by the bending test. The Salt Spray test confirmed EIS ranking of coatings’ corrosion resistance. GDOES elemental profiling revealed that sol-gel coatings thickness increases with organic content. However, this had not necessary implied a better corrosion behaviour. The best corrosion performance was achieved by the hybrid coating with a Zr/Si molar ratio of 0.26.DM/NMM201430 junho- 2 julh
Robustness and risk evaluation of bridge falsework structures
No full textBridge falsework systems are one of the most common temporary structures used in the construction industry, namely to support the formwork during the construction, rehabilitation or retrofit works of concrete bridges and viaducts. A key contribution of this paper is to propose a novel risk management methodology based on newly developed robustness and fragility indices. Advanced stochastic investigations are carried out, in which the key variables that control the stochastic behaviour of bridge falsework systems are identified.
Possible strategies to increase robustness and decrease fragility are discussed. The information gathered in this paper can be used to develop more rational and reliable bridge falsework structures thus safer and more design efficient.8215DE/NCE201426 a 28 de novembr
Qualidade e tratamento de água e águas residuais. Desafios e oportunidades
No full textVivem-se hoje grandes e rápidas mudanças catalisadas por fortes pressões físicas e económicas. As alterações climáticas agravam os cenários e a incerteza a eles associada. São múltiplos e complexos os desafios que se colocam aos sistemas urbanos de água na proteção da saúde e do ambiente. Os contaminantes emergentes, as afluências pluviais, a reutilização de água, a capacidade de adaptação rápida a variações severas da água a tratar e a melhoria da eficiência energética são exemplos de desafios que exigem frequentemente soluções de compromisso e para os quais as ETA e as ETAR podem não estar preparadas, em Portugal e pelo mundo fora, uma vez que não foram considerados no seu projeto. As entidades gestoras têm agora que dar respostas e a inovação na exploração dos sistemas pode ser a chave para o sucesso. Inovação ao nível da abordagem, necessariamente integradora, de controlo na fonte e de remediação, e do benchmarking dos sistemas de tratamento, convencional e avançado, em cenários de seca e de precipitação, que permitam identificar onde, quando e como melhorar e intervir nos sistemas de tratamento e nas redes associadas (sistemas de abastecimento de água e de drenagem de residuais pluviais e residuais) são temas para os quais o LNEC tem vindo a procurar respostas, como aqui se pretendeu ilustrar.114phttp://www.industriaeambiente.pt/scid/webIA/includes/book/viewBook.asp?articleID=2141Nº 84DHA/NESIndústria e Ambient
Use of soil-rock mixtures in dam construction
No full textThe employment of non-traditional materials such as soil–rock mixtures, for economic and environmental reasons, in the construction of earthworks poses some new challenges for compaction techniques and their control as well as for the determination of the characteristics of the embankment that result from the compaction method. Those characteristics experience important changes according to the relative percentages of the existing fractions. Usually, this kind of material results from bulky rock extraction without explosives, and it can include some large size particles (greater than 0.5 m). In addition, the measured deformations associated with these materials have been larger than expected. For the execution control of the soil–rock mixtures from the Odelouca dam borrow areas, a series of vibratory and standard compaction tests was performed to estimate reference values for the maximum dry density and optimum water content of these materials and a new methodology was proposed. Odelouca dam is a zoned embankment dam, 76 m high, with clayey soil in the core and weathered schist with a significant fraction of oversized particles in the shells. This paper presents the results of the compaction control as well as the dam performance during the construction and first filling phases as a validation of implemented construction procedures.11ppVolume 140 / Nº 8DG/NGOHJournal of Construction Engineering and Managemen
Aproveitamento hidroelétrico de Foz Tua condições de escoamento no canal a jusante
No full textO Aproveitamento Hidroelétrico de Foz Tua, um dos projetos da responsabilidade da EDP
atualmente em construção em Portugal, situa-se no rio Tua, próximo da sua confluência com
o rio Douro, e será equipado com dois grupos geradores reversíveis.
Para garantir as adequadas condições de escoamento, principalmente em bombagem a
partir da albufeira da barragem da Régua, no rio Douro, verificou-se ser necessário proceder
à escavação de um canal no leito do rio Tua entre a zona da restituição da central e a
confluência com o rio Douro.
Para definição do referido canal foram conduzidos estudos ao longo das diversas fases do
projeto do aproveitamento em causa, tendo-se realizado análises hidrodinâmicas apoiadas
em modelos numéricos unidimensionais e bidimensionais, desenvolvidos na EDP, e ensaios
em modelo físico reduzido, realizados no LNEC.
Na presente comunicação, após descrição das principais características do Aproveitamento
Hidroelétrico de Foz Tua, são apresentados os pressupostos e critérios considerados nos
estudos antes referidos, bem como os principais resultados obtidos nas análises numérica e
física realizadas e respetiva análise comparativa.DHA/NRE20145 a 8 març
Portugal’s river basin management plans: groundwater innovative methodologies, diagnosis, and objectives
No full textThe European Union Water Framework
Directive aims to protect inland surface waters, transitional
waters, coastal waters, and groundwater and achieve certain
environmental objectives through the implementation
of programs of measures specified in river basin management
plans (RBMPs). For that purpose, information systems
have been identified as a priority tool for managing
water resources effectively and efficiently, within the
process of characterization and modelling of quantitative
and qualitative aspects of groundwater bodies, also considering
the projected climate change scenarios. This paper
addresses some of the innovative issues developed in
Portugal for RBMPs, exemplified for the Tagus and for the
West RBMPs, e.g. modelling groundwater recharge
assessment under climate change scenarios projected for
2071–2101 for the aquifer system of Torres Vedras (West
RBMPs). Regarding groundwater depending ecosystems, a
methodology to classify regional surface water bodies in
hydraulic connection with the underlying body of
groundwater is presented. A synthesis of the diagnosis and
the proposed objectives is presented for Tagus and West
RBMPs. The full report was published by the Consortium
that developed the Groundwater Component (Lot 2),
formed by Hidroprojecto, LNEC and ICCE, in Lobo
Ferreira et al. (Conso´rcio Hidroprojecto/LNEC/ICCE. LNEC, Report 289/2011–NAS 1056 2011a, Conso´rcio
Hidroprojecto/LNEC/ICCE. LNEC, Report 290/2011–
NAS 597 2011b).DHA/NREEnvironmental Earth Science
iGPI and PGPI: national-scale cooperative R&D rollout of IAM planning methods and tools
No full textThe National Iniciative for Infrastructure Asset Management (iGPI) led by LNEC, IST and Addition, and its twin initiative PGPI, led by AGS, were collaborative projects through wich a total of 30 Portuguese water utilities developed IAM systems and plans through a collective trainnig, capacitation and R&D rollout programme (Apr 2012 - Oct 2013). The utilities received specialized training, collective and individual sipport, and networked with the other utilities in a commom process with similar difficulties and challenges, leading to an effective sharing of solutions. The products, including software, training materials, guidelines and templates for developing strategic and tactical IAM plans, are in the public domain. The projects have significantly contributed to the rollout of reference methodologies and standards for IAM planning, demonstrated in a range of utilities of varied size and context, successfully pushing a consensual best pratice. The methodology and outcomes are discussed and illustrated with selected cases.8 pComunicação apresentada no IWA World Water Congress and Exhibition 2014, 21-26 Septembre, Lisbon, Portugal.DHA/NE