Artigos de Revista

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.

Está em curso um projeto de geminação a cargo de um consórcio franco-português, ao abrigo do Acordo de Associação Argélia-UE, que tem por objetivo prestar apoio ao "Organisme National de Contrôle Technique des Travaux Publics" (CTTP) argelino na implementação de um sistema de suporte à decisão para a gestão da rede de estradas e das obras de arte rodoviárias. Neste artigo pretende-se dar a conhecer sumariamente os principais aspetos desta interessante cooperação científica e técnica internacional, em que Portugal é representado pelo Laboratório Nacional de Engenharia Civil (LNEC).

This paper describes a methodology to determine the optimal size of a Wells turbine to be used in an OWC device taking into account hydro-aerodynamic coupling, performance curves of the turbine and air pressure control by a relief valve. The proposed model, named turbine diameter optimization (TDO) model, considers the movement of the water surface inside the OWC chamber as a piston movement in response to the hydrodynamic forces from the incoming waves. The aerodynamic is based on the first law of thermodynamics applied to the air column of the chamber. The power-pressure curve of the turbine and the air pressure control by relief valve are implemented in the model to determine the turbine power output for several regular incident waves. The TDO model is initially calibrated by a numerical model based on Reynolds-Average-Navier-Stokes (RANS) equations for each wave component of an expected sea state distribution. Thereafter, the power output generated by turbines of several sizes is calculated with lower computational cost (few minutes) in comparison with RANS based models (thousands of hours) in a personal computer. This developed methodology is an important support to the process of turbine sizing for an OWC device for an expected sea state distribution.

This paper analyses the possibility of using air curtains to prevent smoke flow from fire compartments. Full size experiments have been carried out and several relevant conditions to assess smoke-tightness have been tested. The smoke temperature during the tests was ranging from 182ºC to 351ºC, the angle measured between the curtain axis and the vertical plane was ranging from 18º and 26º, the nozzle thickness was ranging from 0.017 m to 0.045 m and the velocity at the nozzle was ranging from 8.3 m/s to 19.9 m/s. During the tests, the air curtain’s nozzle was positioned horizontally at the top of a permanent opening (door). With this configuration, we obtained an approximately vertical downward jet through the used opening. This paper includes the final results of the tests and develops an analytical tool for predicting the performance of air curtains. It was concluded that it is possible to achieve smoke-tightness, provided that the adequate plane jet parameters and the compartment’s smoke exhaust are correctly adjusted. According to this analysis, the smoke-tightness limit corresponds to equation B=??P?_a???P?_s =-0.30 u_a?u_(a_min) +1.25 (with 1.30? u_a?u_(a_min) ?1.67).

This paper describes the preliminary developments of an innovative integrated tool for the numerical modelling of oscillating water column (OWC) wave energy converters (WEC) integrated in vertical breakwaters. The main purpose of the tool is the numerical modelling of wave propagation from offshore to nearshore, wave-structure interaction, and the complex nonlinear hydrodynamic and aerodynamic phenomena that occur in OWC-WECs. The tool development and validation were supported by experimental data from physical model tests carried out in a wave flume at the Portuguese National Laboratory for Civil Engineering (LNEC). Prototype data were also available for the Pico OWC-WEC in the Azores, Portugal, monitored by the Portuguese Wave Energy Centre since 2005. Application of the tool for sea-wave characterization at the Azores archipelago and calculation of the corresponding wave power for a period of 10 years at various points around each island show that, in winter, there is good availability of wave energy in most quadrants of each island. In summer, the resource exploitation is only worthwhile on the north-west coasts of the islands. Physical and numerical modelling results for an OWC with a fully open chamber show good agreement between experimental data and numerical values for several incident wave conditions. The analysed results include the time series of the free-surface elevation at different locations, the time series of the mean free surface inside the water chamber, the amplification factors, the phase angles and the velocity vectors at the highest and the lowest positions of the mean free surface inside the chamber. The tool showed its potential to be useful in supporting ocean and coastal engineering projects due to its capacity to effectively reproduce the main phenomena involved in these types of studies.

Joint statistical models for long-term wave climate are a key aspect of offshore wind engineering design. However, to find a joint model for sea-state characteristics is often difficult due to the complex nature of the wave climate and the physical constraints of seastates phenomena. The available records of wave heights and periods are often very asymmetric in their nature. This article presents a copula-based approach to obtain the joint cumulative distribution function of the significant wave heights and the up-crossing mean period. This study is based on 124-month hindcast data concerning Horns Rev 3 offshore wind farm. The extra-parametrization technique of symmetric copulas is implemented to account for the asymmetry present in the data. The analysis of the total sea, the wind-sea and primary swell components is performed separately. The results show that the extra-parametrization technique with pairwise copulas consistently provided a better goodness-of-fit when compared to symmetric copulas. Moreover, it is demonstrated that the separation of the total sea into its components does not always improve the extra-parametrized copula’s performance. Furthermore, this article also discusses copulas application to offshore wind engineering.

Neste artigo abordam-se, especificamente, as bay-windows e o que se designa de outros "lugares-janela", ou "sítios junto à janela", por se considerar que, em termos de uma satisfação global e caracterizada dos habitantes, tais elementos podem assumir uma expressiva importância, associada a interessantes aspectos de apropriação e de satisfação no interior das nossas casas, até porque proporcionando o estar quase “lá fora”, mas bem abrigados e rodeados pelos nossos mundos domésticos.

A nossa habitação pode e deve ser e ir evoluindo, gradualmente, no sentido de ser verdadeiramente a nossa “casa”, base amigável e estimulante dos nossos mundos pessoais, e assim, suporte directo da nossa identidade familiar e individual, uma verdadeira “casca de caracol”, bem à nossa medida, física, psicológica e afectivamente. Neste sentido, no artigo aborda-se este tema, globalmente, e em seguida apontam-se associações e hábitos interessantes sobre recantos domésticos, assim como alguns dos mais significativos aspectos ligados a estes recantos, em termos de motivação para o seu uso, problemas mais correntes e outras questões que aí, frequentemente, se colocam (dimensionais e outras).

Neste primeiro artigo sobre a caracterização dos vãos exteriores é, essencialmente, desenvolvida uma referência à decisiva importância que os vãos exteriores domésticos assumem, globalmente, em termos de satisfação dos habitantes e de adequado desenho arquitectónico (matérias que têm de estar bem aliada) e a respectiva e específica importância que os vãos exteriores assumem em termos de conforto ambiental, considerando a luz natural, a insolação e o isolamento térmico, a ventilação natural, o isolamento acústico e a estratégica abertura de vistas exteriores.