Últimos itens adicionados do Acervo: Laboratório Nacional de Energia e Geologia

O Laboratório Nacional de Energia e Geologia (LNEG) é uma instituição de I&D orientada para responder às necessidades da sociedade e das empresas. Apostando numa investigação sustentável e para a sustentabilidade através da geração do conhecimento em Portugal.

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‣ Methodological development of sesonal cooling energy needs by introducing ground-cooling systems

Oliveira Panão, Marta; Gonçalves, Helder
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em //2011 Português
In past years, building professionals increased their interest on passive systems as sustainable solutions to reduce energy needs. This has been driven by the building certification program and new Portuguese building thermal code enacted in 2006. For residential and small office buildings, the methodology adopted is a seasonal quasi-stationary approach for calculating cooling energy following EN ISO 13790:2007. However, this method lacks specific recommendations for accounting passive cooling systems, namely ground-cooling systems. In this paper, the ground-heat exchanger contribution is included in the energy needs method. This development is sustained by measurements obtained in the ground-heat exchanger running on Solar XXI office building at LNEG campus, complemented by simplified and Fourier theoretical formulations. The horizontal ground-heat exchanger at Solar XXI is constituted by 32 concrete ducts, with a 30 cm diameter and buried 4.6 m deep. The air entrance is made from a feeding well about 15 m away from the building and its functioning during summer warm days supplies cool air for room offices.

‣ A PV/T and Heat Pump based trigeneration system model for residential applications

Joyce, António; Coelho, Luis; Martins, João F.; Tavares, Nelson; Pereira, R.; Magalhães, Pedro
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em //2011 Português
A solar trigeneration system, based on photovoltaic-thermal (PV/T) collectors, photovoltaic (PV) modules and a heat pump unit for heating and cooling, is modelled to forecast the thermal and electric yields of the system. The aim of the trigeneration system is to provide enough electricity, domestic hot water (DHW), heating and cooling power to meet the typical demand of an urban single family dwelling with limited roof area and allow the household to achieve a positive net energy status. The PV/T collectors and PV modules provide the electricity while the former also powers the DHW component of the trigeneration system. The heating and cooling components rely on a vapour compression cycle heat pump unit powered by electricity. In Fong et al. (2010), solar-powered electric compression refrigeration was found to have the most energy saving potential in subtropical climates. Thus, a heat pump based cooling system is a cost effective solution for residential applications in Lisbon,Portugal. Thus, according to the dwelling's location, construction details and energy demand patterns, the model computes the system's net results by comparing the dwelling demand with the trigeneration system supply. The paper presents a breakdown of the proposed trigeneration system model and describes each component briefly. Preliminary results produced by the model are presented and analysed in order to identify possible ways of improving the overall system performance.

‣ Non-linear Slack-Mooring Modelling of a Floating Two-Body Wave Energy Converter

Vicente, Pedro C.; Falcão, António de O.; Justino, Paulo Alexandre
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em //2011 Português
Most floating oscillating-body wave energy converters that have been proposed and developed so far are two-body systems where the power is extracted from the relative translational motion between the two bodies. As any floating device, floating point absorbers are subject to drift forces due to waves, currents and wind, and therefore need to be kept in place by a proper mooring system. The mooring cables can be approximately modelled as catenary lines in a quasi-static analysis. The use of a time-domain analysis allows for nonlinear mooring forces of slack chain cables to be considered. Numerical results for motion, mooring tensions and absorbed power are presented for a two body system consisting of a hemispherical floater and a submerged body and slack bottom moorings, for regular and irregular waves. Comparisons are given with the unmoored two-body heaving system, the moored heaving twobody system and with the simplified one body linear PTO model. Results show the possibility of occurrence of low-frequency horizontal oscillations of large amplitude, and non linear motions, even for regular waves. Some differences are seen in comparison with the simplified one body model and with the heave two-body system. The moorings were found not to affect very significantly the power absorbed.

‣ (Meta)cherts, (meta)lydites, (meta)phtanites and quartzites of the Série Negra (Crato-S. Martinho), E Portugal : towards a correct nomenclature based on mineralogy and cathodoluminescence studies

Oliveira, Daniel P. S.; Reed, R. M.; Milliken, K. L.; Robb, L. J.; Inverno, Carlos; D'Orey, Fernando L. C.
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em /06/2003 Português

‣ Manufacture of cordierite foams by direct foaming

Silva, Elisabete Ribeiro; Correia, N.; Silva, J. M.; Oliveira, F. A. Costa; Ribeiro, F. R. M. C.; Bordalo, J. C.; Ribeiro, M. F.
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Artigo de Revista Científica
Publicado em //2007 Português
Open cell cordiereti fosms were prepared by a direct foaming two-component polyurethane (PUR)/ceramic system. Throught optimization of several experimental parameters such as contents of catalysts and ceramic cordiereti precursor, as well as plasticizer presence, foams with porosites 85-95&% and densities ranging from 130-410 kg/m3 were obtained. Thse foams characteristics make them attractive to be used as catalyst supports. The new two-component PUR/ceramics system developped allows the high solid's loading (higher than 40 wt. %). Finer ceramic particles in this system provide better particles packaged and cohesion upon sintering, favouring the cordiereti foam stability.

‣ Chroniberia : the ongoing development of a geochronological GIS database of Iberia

Lopes, C.; Ferreira, A.; Chichorro, Martím A.; Pereira, M. Francisco; Almeida, J. A.; Solá, Ana Rita
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em //2014 Português

‣ Deciphering a multipeak event in a noncomplex set of detrital zircon U-Pb ages

Ferreira, A.; Lopes, C.; Chichorro, Martím A.; Pereira, M. Francisco; Solá, Ana Rita
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em //2014 Português

‣ Syn-rift unconformities punctuating the lower-middle Cambrian transition in the Atlas Rift, Morocco

Álvaro, J. Javier; Ezzouhairi, Hassan; Clausen, Sébastien; Ribeiro, Maria Luísa; Solá, Ana Rita
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Artigo de Revista Científica
Publicado em /04/2015 Português
The Cambrian Tamdroust and Bab n’Ali Volcanic Complexes represent two magmatic episodes developed in the latest Ediacaran–Cambrian Atlas Rift of Morocco. Their rifting pulses were accompanied by accumulation of volcanosedimentary edifices (dominated by effusive lava flows in the former and explosive acidic aprons in the latter) associated with active tilting and uplift. Sealing of their peneplaned horst-and-graben palaeotopographies led to the onset of distinct onlapping geometries and angular discordances capping eroded basements ranging from the Ediacaran Ouarzazate Supergroup to the Cambrian Asrir Formation. Previous interpretations of these discordances as pull-apart or compressive events are revised here and reinterpreted in an extensional (rifting) context associated with active volcanism. The record of erosive unconformities, stratigraphic gaps, condensed beds and onlapping patterns across the traditional “lower–middle Cambrian” (or Cambrian Series 2–3) transition of the Atlas Rift must be taken into consideration for global chronostratigraphic correlation based on their trilobite content.

‣ Deciphering a multi-event in a non-complex set of detrital zircon U-Pb ages from Carboniferous graywackes of SW Iberia

Ferreira, A.; Lopes, C.; Chichorro, Martím A.; Pereira, M. Francisco; Solá, Ana Rita
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Artigo de Revista Científica
Publicado em /06/2014 Português
The determination of U–Pb ages from detrital zircons of sedimentary rocks using LA-ICP-MS has been widely used for the purpose of provenance analysis. One problem that frequently arises is finding a population that appears to be non-complex despite several perceptible age peaks in its spectrum. These peaks are qualitatively defined by means of relative probability diagrams, or PDFs, but it is difficult to quantify their statistical significance relative to a zircon forming multi-event. Thus, can a multi-event in a non-complex set of detrital zircon U–Pb ages be deciphered and characterized? The aim of this study is to attempt to provide an answer to this question by means of statistical analysis. Its objectives are: a) to determine the best minimum number of zircon age populations (peaks), BmPs, b) for the characterization of each peak in terms of age and event duration; c) to compare the results obtained from two datasets showing similar zircon ages; and d) to demonstrate the usefulness of deciphering these BmPs. First, cluster analysis is carried out, aimed at grouping zircon ages into a set of consistent clusters. A Gaussian Kernel function is then fitted to each cluster and summed to obtain a theoretical PDFm (modeled probability density function). Finally...

‣ Intra-crustal recycling and crustal-mantle interactions in North Gondwana revealed by oxygen isotopic composition of Neoproterozoic to Ordovician zircons from SW Iberia rocks

Chichorro, Martím A.; Solá, Ana Rita; Pereira, M. Francisco; Sánchez-García, Teresa; Ferreira, A.; Silva, J. Brandão; Armstrong, R.
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em /06/2014 Português

‣ Correlation directe de la variabilité climatique ocean-continent des derniers 25.000 ans a partir de l'analyse multi-proxy d'une carotte marine de la marge Nord-Ouest Ibérique

Naughton, Filipa; Sánchez Goñi, María Fernanda; Desprat, Stéphanie; Turon, Jean-Louis; Duprat, Josette; Cortijo, Elsa; Malaizé, Bruno; Joly, C.; Bard, Edouard; Rostek, Franke
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em /09/2005 Português

‣ Millennial-scale climatic variations in northwestern Iberia during the last 25.000 years from the MD99-2331 pollen-rich deep sea core

Naughton, Filipa; Sánchez Goñi, María Fernanda; Turon, Jean-Louis; Duprat, Josette; Bard, Edouard; Rostek, Franke; Desprat, Stéphanie; Malaizé, Bruno; Joly, C.
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em /09/2004 Português

‣ Complex pattern of Heinrich events in the mid-latitudes of the North-east Atlantic explained by oceanic and atmospheric mechanisms

Naughton, Filipa; Sánchez Goñi, María Fernanda; Duprat, Josette; Cortijo, Elsa; Malaizé, Bruno; Joly, C.; Bard, Edouard; Rostek, Franke; Turon, Jean-Louis
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em /04/2007 Português

‣ Neoproterozoic magmatism and metamorphism at the northern margin of Gondwana : Ossa Morena/Central Iberian zone boundary (Central Portugal)

Henriques, Susana; Neiva, Ana Margarida R.; Ribeiro, Maria Luísa; Dunning, G. R.; Tajcmanova, L.
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em /07/2014 Português

‣ A new Echinoderm Lagerstätte in Portugal : preliminary results

Pereira, Bruno Claro; Pereira, Pedro; Machado, Susana; Carvalho, Jorge M. F.; Mergulhão, Lia
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em /10/2014 Português

‣ Mg/Ca within the shell of the bivalve Pecten maximus : a new palaeotemperature proxy and implications for bivalve shell geochemical proxies

Freitas, Pedro Seabra; Clarke, Leon J.; Kennedy, H. A.; Richardson, Christopher A.
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em /04/2009 Português

‣ An examination of potential controls on shell Mn-Ca ratios in the calcite of the bivalve Mytilus edulis

Freitas, Pedro Seabra; Clarke, Leon J.; Kennedy, H. A.; Richardson, Christopher A.
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em //2008 Português

‣ Experimental calibration of the oxygen-isotope palaeotemperature proxy in the shells of the bivalves Mytilus edulis and Pecten maximus

Freitas, Pedro Seabra; Clarke, Leon J.; Kennedy, H. A.; Richardson, Christopher A.
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Trabalho em Andamento
Publicado em /06/2008 Português

‣ A structural study of Cr-spinels from mantle xenoliths of Cameroon, Libya and Morocco

Lenaz, David; Musco, M.; Caldeira, Rita; De Min, A.; Marzoli, Andrea; Mata, J.; Princivalle, Francesco; Youbi, N.
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em /09/2014 Português
DE3 - Mineralogy in the deep earth - Poster

‣ Contrasting Ordovician high- and low-pressure metamorphism related to a microcontinent-arc collision in the Eastern Cordillera of Perú (Tarma province)

Willner, Arne P.; Tassinari, Colombo C. G.; Rodrigues, José Feliciano; Acosta, Jorge; Castroviejo Bolíbar, Ricardo; Rivera, Miguel
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Artigo de Revista Científica
Publicado em /10/2014 Português
High-pressure conditions of 11–13 kbar/500–540 °C during maximum burial were derived for garnet amphibolite in the Tapo Ultramafic Massif in the Eastern Cordillera of Peru using a PT pseudosection approach. A Sm–Nd mineral-whole rock isochron at 465 ± 24 Ma dates fluid influx at peak temperatures of ~600 °C and the peak of high pressure metamorphism in a rodingite of this ultramafic complex. The Tapo Ultramafic Complex is interpreted as a relic of oceanic crust which was subducted and exhumed in a collision zone along a suture. It was buried under a metamorphic geotherm of 12–13 °C/km during collision of the Paracas microcontinent with an Ordovician arc in the Peruvian Eastern Cordillera. The Ordovician arc is represented by the western Marañon Complex. Here, low PT conditions at 2.4–2.6 kbar, 300–330 °C were estimated for a phyllite–greenschist assemblage representing a contrasting metamorphic geotherm of 32–40 °C/km characteristic for a magmatic arc environment.