Artigos de Revista

The Discrete Element Method (DEM) has been increasingly used to study the behaviour of rock. Despite theadvantage of classical DEM formulations in using simple interaction laws to model fracture initiation and propagation, they have limitations to properly simulate brittle rock behaviour. The code cannot predict the highvalues of unconfined compressive strength/tensile strength (UCS/TS) ratio associated with non-linear failureenvelopes, as observed for hard rock, such as granite, unless significant modifications are made. This paperproposes and implements a clumped-particle model into a two-dimensional DEM code. The increase in theinteraction between discrete elements, which locally increases the density of interparticle bonds, can improvethe results to obtain the desired values of UCS/TS ratio. This approach seems able to significantly increase both the potential and the predictive capabilities of DEM for rock modelling purposes. The novelties introduced in this work are the presentation of a numerical procedure to determine the equivalent micro-mechanical properties of intact rocks and, aware of a gap in our knowledge, the characterisation of uncertainties that a clumped-particle model introduces in the numerical results. A series of numerical simulations, including uniaxial compression and direct tension tests, were carried out, by varying the relation between the clump and the minimum particle radius, using the Monte Carlo simulation technique. The results were compared with experimental data on Lac du Bonnet granite, from the bibliography, which allowed to determine the equivalent micro-mechanical properties. Results, from a simulation using a core sample of Lac du Bonnet granite, show that the variance in the values of the mechanical properties calculated decreases with the decrease in the particle radius, but the influence of the clump size on the behaviour requires the execution of a considerable amount of simulations to achieve results with an acceptable relative error of 5%. Nevertheless, the mechanical behaviour obtained from DEM simulations was in good agreement with the experimental data and the model captured both the tensile and the unconfined compression strength values.

As metodologias de tratamento solo-aquífero (Soil-Aquifer Treatment ou SAT) são aqui estudadascomo meio complementar para a remoção de contaminantes de águas residuais tratadas, como propósito de melhorar a qualidade da água infiltrada em bacias para recarga controlada deaquíferos (Managed Aquifer Recharge ou MAR). Foram realizados ensaios em coluna com o soloda área anexa à ETAR de São Bartolomeu de Messines (Algarve) e analisados, na água de injeçãoe na água de saída, um conjunto de nutrientes, metais e compostos farmacêuticos. Foi possívelobservar a redução de alguns destes compostos (amónia, diclofenac e carbamazepina) e verificara persistência de outros (boro, zinco, cobre, nitratos, gemfibrozil e naproxeno) após a percolaçãoda água pelo solo.

O presente artigo, alicerçado nos Projetos de investigação CyberParks e C3Places, examina como as tecnologias digitais podem envolver os utilizadores na cocriação de um espaço público aberto que responda às suas necessidades, explorando o papel mediador das Tecnologias da Informação e da Comunicação (TIC) nesse processo. Partindo de resultados preliminares dos dois projetos, será explorado mais especificamente o uso do espaço público por adolescentes e discutida a necessidade de repensar o espaço público através de uma perspetiva mais participada.

Depois de uma pequena introdução sobre a relação entre os equipamentos e e as instalações domésticas e a qualidade arquitectónica, desenvolve-se uma reflexão geral sobre equipamentos e instalações domésticas, abordam-se alguns aspectos considerados relativamente

Na Europa, e de uma forma geral por todo o mundo, existe uma grande procura de agregados para a construção civil, principalmente para a construção de estradas. Existe também uma preocupação crescente com a conservação dos recursos naturais e com o ambiente, que tem levado à procura e utilização de agregados secundários, nomeadamente resíduos/subprodutos industriais cujas propriedades químicas, físicas, mecânicas e ambientais viabilizam a substituição dos agregados naturais, como é o caso desde há longa data dos agregados de escórias de aciaria. As escórias de aciaria são resíduos/subprodutos inevitáveis do fabrico do aço, os quais após um processamento adequado constituem agregados artificiais de excelente qualidade, segundo váriosautores, para o fabrico de misturas betuminosas a aplicar em camadas de pavimentos rodoviários.A par do crescimento da indústria do aço a nível mundial, encontra-se assim a produção de escórias de aciaria e a necessidade de se identificarem soluções para o seu aproveitamento. A sua utilização na construção de estradas, como material alternativo aos agregados naturais é já há algumas décadas a sua principal aplicaçãoem vários países, constituindo uma alternativa relativamente abundante e promissora.Este artigo caracteriza o estado do conhecimento na Península Ibérica e no Brasil, relativamente ao uso de escórias de aciaria (em particular, de forno de arco elétrico) em misturas betuminosas para pavimentos rodoviários.

In many water distribution systems, water losses are a major problem and an integrated management strategy is required for both the efficient use of water resources and the minimisation of non-revenue water. For foul sewer systems, the inflow of stormwater and infiltration of groundwater affects the management of both sewer systems and wastewater treatment plants. Monitoring of flows represents a critical task within approaches for control of either water losses in distribution systems and infiltration and rain-induced inflows in foul systems. Implementation of monitoring typically involves the following steps: (i) system information updating and digital mapping; (ii) system zoning; and (iii) system flow monitoring. Costs for monitoring are essential for utilities to estimate more accurately the costs of control of water losses, infiltration and inflow and to support more robust decision-making. Costs and infrastructure data were collected from 20 Portuguese water and wastewater utilities. Multiple linear regression analysis is used to obtain cost functions for meter chambers as a function of the volume and for purchase and installation of flow meters as a function of nominal diameter in water supply systems. For the steps of system information updating, digital mapping and system zoning single unit costs are estimated.

The construction sector has a key role to play in achieving the global objectives of sustainabledevelopment. At the request of society and consumers, there is a growing incentive to use sustainableand environmentally friendly construction materials, also with lower energy incorporated.Biocomposites, containing biopolymers and/or natural fibres, have less built-in energy thanconventional materials traditionally used by the construction industry. This aspect has originatedsignificant increase in their use in the field of construction.While biocomposite products already perform satisfactorily in many construction applications, they stillneed to be upgraded in some specific characteristics that are undergoing research and technologicaldevelopment. Sometimes bio-materials are strongly formulated or coupled with nanomaterials, toimprove some specific properties of the final product.Like a conventional construction product, these biobased materials and products need to be specifiedaccording to building regulations and small-scale assemblies and full-sized test rigs need to besubjected to testing and evaluation to industry and standards targets.Thus, in environmental conditions of application they not should show curvature, swelling, decohesionor other signals of degradation, delamination or fracture, they should have good biologic resistance,good reaction to fire, no flaming or no flame spread, and minimum quantified mechanical properties willbe required.In this communication final products for building façades, constituted by bio-composites, as well asVeture panel for thermal insulation consisting of WPC (skin) and an nanoaerogel core (insulationmaterial), are assessed at macro scale.The results are analysed and discussed taking into account the current requirements for theconstructive applications in view and its fitness for use is evaluated.

Connecting storm-sewers located at rather different elevations may be made with vortex drop shaftsin which the energy dissipation is made by the friction between the vertical shaft and the flow anddownstream by the impinging jet in a dissipation chamber. Following the first model design in the1940s, different types of vortex drop shafts have been developed. One of the most used type is theso-called spiral vortex drop shaft developed to work in supercritical flow with good performance inboth energy dissipation and space constrains. In this paper, an experimental flow characterization ina spiral vortex drop shaft is conducted covering the three main components of these structures,namely the inlet channel, the vertical shaft and the dissipation chamber. The results includemeasurement of water depths, pressure and velocity.

The aim of this paper is the experimental characterization of the capture width ratio (CWR) and response amplitude operator (RAO) of a 1:10 physical model of an oscillating wave surge converter (OWSC), under unidirectional regular and irregular waves. The effects of hydraulic power take-off (PTO) system are explicitly taken in consideration. A mathematical model is proposed to describe the PTO damping as a function of the angular velocity of the flap. The harmonic decomposition of free-surface elevation, angular velocity of the flap and pressure in the PTO system demonstrates that these signals are dominated by their linear component. However, the signals also present some important higher-order frequency components. To predict the CWR of the OWSC under irregular waves the nonlinear output frequency response functions are considered as the extension of the RAO to the nonlinear case. It is shown and discussed that the PTO system, wave frequency and height have a significant influence on the CWR and RAO. The RAO curve for irregular waves does not exhibit a well-defined peak, showing a limited variation in a broadband. A weak correlation between CWR and RAO was found, i.e., the maximum CWR does not occur for the maximum value of RAO.