Browsing by Issue Date, starting with "2007-09"
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- Higher frequency of turbidites during abrupt climatic "Heinrich" and "Dansgaard-Oeschger events" - evidence for slope instability on the Portuguese MarginPublication . Lebreiro, Susana; Voelker, Antje H. L.; Alt-Epping, Ulrich; Vizcaino, A.; Jung, S.; Abrantes, Fátima; Gràcia i Mont, Eulàlia
- Looking for earthquake sources in the Lisbon areaPublication . Carvalho, João P. F.; Pinto, Carlos C.; Costa, M.; Rabeh, TahaThe Lisbon and surrounding areas have suffered the effect of historical earthquakes that caused important damages and loss of lives. Some of these earthquake sources are local but they are still poorly known. The knowledge of these sources is important for seismic hazard studies. The use of geophysical methods in the area is required due to the difficulty in finding geological outcrops, together with low-slip rates and erosion/sedimentation processes that erase surface ruptures. Furthermore, most of earthquake occurs at great depth, emphasizing the need for the application of the latter methods. In this paper we present a revised structural interpretation of the area using newly reprocessed and reinterpreted seismic reflection and potential-field data, relocated epicentres, geological outcrop and well data. This interpretation differs in some aspects from previous ones. Well known active faults zones like the Azambuja fault and the Pinhal Novo-Setúbal fault have new interpretations, while other previously unknown structures, like the Ota-V. F. de Xira-Lisbon-Sesimbra fault zone, for example, have been interpreted. These studies, together with shallow geophysical data, which has been and will be acquired over selected targets from this work, will constitute na improvement to the seismic hazard evaluation of the area.
- Integrating Offshore Wind and Wave Resource AssessmentPublication . Pontes, M.T.; Sempreviva, A.M.; Barthelmie, R.; Giebel, G.; Costa, Paula Silva; Sood, A.The aim of this paper is to review the sources of wind and wave information, the methodologies to assess offshore wind and wave energy resources, and the more relevant results at the European level as a first step to integration of the evaluation of both resources. In situ and remote sensed wind and wave data (using satellite based sensors) are done generally by distinct systems (except for SAR) but numerical atmospheric models and wind - wave models are closely related. Offshore wind resource studies using various types of data are reviewed especially in northern European seas and in the Mediterranean. The wave energy resource assessment at European and national levels is also reviewed and the various atlases are identified.
- Spectral Bandwidth and WEC Performance AssessmentPublication . Saulnier, J.-B.; Ricci, P.; Pontes, M.T.; Falcão, António F. de O.This paper investigates the dependency of wave energy conversion on the spectral bandwidth of sea-states. To this aim, the performance of an axisymmetrical Wave Energy Converter is assessed in the frequency domain by using a stochastic model in two far different wave climates (Portugal and North Sea) both represented by more than 23000 energy spectral densities obtained from measurements. The correlation between the performance and various bandwidth parameters found in the literature is observed. Then, refined methods for predicting the long-term converted wave energy based on wave statistics including spectral bandwidth are compared to more common procedures and conclusions are drawn.
- Wave energy resource in the North SeaPublication . Beels, C.; Henriques, J.C.C.; De Rouck, J.; Pontes, M.T.; De Backer, G.; Verhaeghe, H.Due to the high potential of wave energy and the goal to raise the share of renewable energy supply in the EU up till 20 % in 2020, the development of wave energy is accelerated. Until now the wave energy resource was highlighted in regions with a high wave energy density. As Wave Energy Converters (WECs) still contend with problems such as structural strength and mooring in a severe and energetic wave climate, the prospects of wave power conversion in a less aggressive wave climate should be investigated. This paper describes the wave power resource in a rather sheltered area i.e., the North Sea. The available wave power is studied on 34 locations. Characteristic sea states are defined for the Belgian, Dutch, German, Danish, Norwegian and UK Continental Shelf. An inverse-ray refraction model, implemented at INETI (Instituto Nacional de Engenharia, Tecnologia e Inovação), is presented to calculate the resource on more convenient locations for wave energy conversion. The wave power potential in the North Sea is compared with the resource of the West European coast. Near shore (< 30 km off the coast) up to a maximum of approximately 11 kW/m is available in the North Sea.
- Layered double hydroxides for aluminium alloys corrosion resistancePublication . Rangel, C. M.; Travassos, Maria AntóniaLayered Double Hydroxides (LDHμs), represented by the general formula [MII (1-x)MIIIx(OH)2[An-x/n].zH2O or [MIMIII2(OH)6[An-1/n].zH2O], where MI, MII, MIII are mono-, di- and tri-valent metal cations, are being researched as anion-exchange materials with interesting intercalation chemistry that accommodate a wide range of applications including corrosion resistance. In this work, layered double hydroxides containing a monovalent (Li+) and trivalent (Al3+) matrix cations, have been synthesized and characterised using X-ray diffraction, FTIR and SEM. LDHμs were prepared by a simple co-precipitation method using metal hydroxides and metal salts in an alkaline solution. Formation of LDHμs on the metal surface of Al alloys were attempted with excellent results. Pitting corrosion was inhibited on Aluminium 2024-T3 with an extensive capability to withstand the presence of high concentrations of chloride ions. The formation of DHLμs is thought to be responsible for inhibition which is demonstrated to be under diffusion control. The action of DLHμs on copper is demonstrated in separated experiments using pure copper samples in similar experimental conditions as for the alloy, in an extensive
- The parautochthonous thrust complex in Trás-os-Montes : essay of tectonostratigraphic correlation between Bragança and V. P. Aguiar sectorsPublication . Pinto de Meireles, Carlos Augusto; Ribeiro, Maria dos Anjos; Couto, Helena
- Frequency-domain and stochastic model for an articulated wave power devicePublication . Cândido, J.; Justino, Paulo AlexandreTo have the first look into device performance, analytical and numerical tools must be used. Assuming that the wave power system hydrodynamics has a linear behaviour, diffraction and radiation coefficients can be computed. If the power take-off equipment may be, for the first approach, regarded as holding a linear behaviour then overall (i.e. hydrodynamic plus mechanical) device performance can be studied for regular waves. In this study a frequency-domain model describes the articulated system behaviour for regular waves. For this paper a stochastic model is found for an articulated wave power device, and probability density functions are defined for the relevant parameters that characterize the wave power system behaviour. For these parameters and for different sea states the probability density functions are found. The articulated system is characterized by these probability density functions. Also, average values for capture width are obtained for these sea state conditions.
- Espumas cerâmicas como suportes catalíticosPublication . Silva, Elisabete Ribeiro; Catalão, R.; Oliveira, Fernando Almeida Costa; Ribeiro, F. M. R. C.; Vaz, M. Fátima; Ribeiro, M. F.Espumas reticulares de cordierite desenvolvidas por um método de polimerização “in situ” revelaram propriedades de elevado interesse para a aplicação como suportes catalíticos. Estas espumas são caracterizadas por possuírem porosidades superiores (>90%) às obtidas pelo método de replicação polimérica (70-85%). O desenvolvimento de um método de revestimento de espumas cerâmicas com catalisadores zeolíticos, e a optimização de parâmetros como teor de sólidos, ligante, surfactante ou pré-revestimento da espuma, tem estado a ser efectuado. As melhores características foram observadas para espumas com aproximadamente 17% (p/p) de revestimento obtidas a partir de suspensões com cerca de 16% de teor de sólidos. Espumas revestidas com zeólitos Pt/ZSM5 estão a ser utilizadas como catalisadores para a combustão catalítica de COVs, nomeadamente isopropanol e tolueno
- Instrumentos de Comunicação :relatórios de sustentabilidadePublication . Duarte, Ana Paula