Artigos de Revista

This paper aims to spatially characterize the marine intrusion in the case of the Bouteldja main aquifer using the GALDIT method coupled with a geostatistical approach. The latter was used to compensate the weakness of GALDIT method for not considering the spatial variability of the studied variables. Using a field data set of the Bouteldja aquifer, the semi-variograms of four continuous important variables (hydraulic conductivity A, groundwater level L, thickness T and sea water intrusion I) were studied and modeled. The obtained structures were mainly composed of spherical models with a small nugget effect, except the I variable which has shown a perfectly continuous Gaussian model with zero nugget effect, arguing that the marine intrusion is seriously present and continuous. These individual results were also mapped by kriging and the intrusion easily shown on the field. However, the GALDIT computation and mapping did not confirm the found intrusion. It has merely shown a medium to low vulnerability in narrow and parallel bands close to the shore area. This work has shown that the GALDIT method used solely, without a geostatistical approach, would lead to a misinterpretation of the vulnerability of a main aquifer to saline intrusion. Keywords  · Shore aquifer · Bouteldja · Vulnerability ·  · Pollution · Salinity

Understanding the out

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

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

A nossa habitação pode e deve ser e ir evoluindo, gradualmente, no sentido de ser verdadeiramente a nossa

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.

Neste segundo artigo sobre a caracterização geral dos vãos exteriores desenvolvem-se algumas reflexões sobre diversas subtemáticas consideradas muito significativas, com destaque para: a segurança contra quedas a partir de vãos e de guardas de pisos elevados; a segurança contra intrusões físicas e visuais em vãos exteriores térreos ou pouco elevados; o desenvolvimento de vãos exteriores "estanques" e com abertura controlada; a escolha e o enquadramento da vistas sobre o exterior; a gradação e melhor reflexão da luz no interior; e a matéria do equilíbrio entre racionalidade e subdivisão das zonas envidraçadas.

The lifetime of a geothermal well is strongly dependent on the long-term performance of the cement used for its construction. The critical zones in well cements are the outermost layers, where the cement encounters either the steel casing or the rock formation. The current paper presents a study of the changes in the interfacial transition zone that forms between geothermal cements and volcanic rocks, after hydrothermal treatment at 290°C. Cement slurries were poured into cavities drilled into ignimbrite blocks and allowed to set at 90°C. The assemblages were autoclaved under typical geothermal conditions, both with and without a carbon dioxide overpressure at 290°C. The addition of silica to the cement dictates the phases that form in cement. When exposed to carbon dioxide, these calcium silicate hydrate phases carbonate, at distinct carbonation rates. The rate at which these phases form and/or carbonate affects the reaction extent of the cement with the rock and, eventually, the cement durability.

The limited durability of the cement in acidic fluids is one of the main issues controlling the lifetime of a geothermal well. The most critical region is the outermost layer of the cement adjacent to the formation.This paper provides insight into the way in which well cementing formulations interact with a common rock formation in geothermal environments, at 150