Browsing by Issue Date, starting with "2010"
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- Petrology and geochemistry of lavas from Sal Island : implications for the variability of the Cape Verde magmatismPublication . Torres, P.; Silva, L. Celestino da; Munhá, José; Caldeira, Rita; Mata, João; Tassinari, Colombo C. G.
- The future energy mix paradigm: How to embed large amounts of wind generation while preserving the robustness and quality of the power systemsPublication . Estanqueiro, AnaThe 2001/77/CE Renewable Energies European Directive together with Kyoto Protocol ratification by many countries, supported by some Governments vision and strong objectives on the reduction of external oil dependence, put Europe and other developed economies in the front line to achieve a remarkable wind energy penetration within ten years time. These goals will not be achieved without technical costs and risks, but mainly,without a careful planning and assessment of the power system behaviour with large amounts of wind generation (SRA, 2008; IEAWind, 2008).These days, one of the most relevant difficulties the wind sector faces was caused by this technology own extreme success. The high capacity installed in the last decade introduced a brand new set of power system technological concerns that recently became one of the more referenced subjects among developers, network planners and system operators. These concerns are not anymore a negligible distribution grid integration issue that some years ago the experts tended not to give too much relevance since they were easily solved and even more easily avoided through good design and planning, but this is a real power system operation and planning challenge (Holttinen et al, 2009): will the power systems be capable to cope with the specificities of the wind power production in large quantities (aka “high penetration”) without requiring new wind park models, system operation tools,increased performance of the wind turbines or even a change in the Transmission System Operators (TSOs) conventional mode of operation? The recent concern of the TSOs is very legitimate, since it is their responsibility to design and manage the power system global production and its adjustment to the consumer loads as well as to assure the technical quality of the overall service, both in steady-state and under transient occurrences.
- A Casa das Pedras em Montesinho, Bragança : aproveitamento didáctico de uma colecção particular de rochas locaisPublication . Meireles, Carlos; Esteves, Eduardo
- Standard Unretrofitted Buildings and Net Zero-Energy ConceptPublication . Aelenei, Daniel; Aelenei, Laura Elena; Santos, M.C. da CostaThere are many different possible combinations of building envelope, utility equipments and onsite energy generation equipments that can lead to net zero-energy performance. For instance, a building with standard design can offset its energy demand by adding a large amount of photovoltaic cells or by improving its energy efficiency rating first and then adding a smaller amount of photovoltaic cells. Despite the second strategy being considered the roadmap to net zeroenergy status, the first scenario is also possible in the actual Portuguese context where laws favor conditions for the installation of PV´s and solar thermal systems. This paper intends to discuss the implications of this fact from a national perspective coupled with the IEA SHC Task 40 - ECBCS Annex 52 vision where authors are active participants.
- Solar XXI : em direcção à energia zero : towards zero energyPublication . Goncalves, Helder; Cabrito, Pedro; Diniz, Isabel
- Building a collaboratory in an engineering R&D organizationPublication . Correia, Zita; Egreja, Catarina; Barrulas, Maria Joaquina; Gil, Rui; Ferreira, Diogo R.This paper presents the results achieved throughout the process of preparing the ground to develop a collaboratory in an Engineering R&D organization. This case study is part of a broader research project engaged in building a collaboratory in order to share knowledge and resources among the Portuguese State laboratories. In the process of preparing the ground to develop the collaboratory in the first of the laboratories studied, an information audit was conducted and an online survey was launched. The survey targeted 241 people, including mainly professional researchers, but also research trainees and some technical staff integrating the research teams. The questionnaire was designed so as to collect data on the organization’s information management and information culture, and on the information flows taking place, and their relationship with the objectives of the organization. The questionnaire comprised two distinct and independent parts. The first (on the organization’s information culture and information management) obtained seventy nine responses, while the second (information flows) achieved ninety two, corresponding to 32,8% and 38,2% of the total population, respectively. The work carried out provided the basic requirements for the task of developing a software infrastructure to support the collaboratory, addressing the various aspects of collaborative tools, information archiving, hierarchical tag classification, search, transparent integration of the user local environment with the platform and remote control of scientific instruments.
- Assessment of the soil contamination by potentially toxic elements in Aljustrel mining area in order to implement soil reclamation strategiesPublication . Candeias, Carla; Silva, E. Ferreira da; Salgueiro, Ana Rita; Pereira, H. Garcia; Matos, João Xavier; Ávila, Paula Freire
- Mineralogia dos filões aplito-pegmatíticos litiníferos da região de SeguraPublication . Antunes, I. Margarida H. Ribeiro; Neiva, A.M.R.; Silva, M. M. V. G.; Silva, Paulo BravoNa região de Segura, os filões aplito-pegmatíticos litiníferos Variscos intruíram o Complexo Xisto-Grauváquico, Câmbrico. Osfilões pegmatíticos são do tipo REL-Li e incluem-se na família dos pegmatitos LCT. A ocorrência de lepidolite, montebrasite, microlite, cassiterite e minerais do grupo da columbite primários sugerem um elevado grau de diferenciação nestes filões. A montebrasite primária é heterogénea e a lacroixite secundária ocorre nas suas zonas enriquecidas em Na. A cassietrite é zonada com alternância de zonas escuras e zonas claras e possui Mn > Fe, o que é raro. As zonas escuras são fortemente pleocróicas, com zonamento oscilatório, e possuem teores mais elevados de Nb e Ta do que as zonas claras. As inclusões de moscovite, apatite, ferrotapiolite, ixiolite e microlite foram encontradas em ambas as zonas de cassiterite, mas as exsoluções de ferrocolumbite, ferrocolumbite manganífera e manganocolumbite ocorrem nas zonas escuras.
- Geochemistry of granitic aplite-pegmatite sills and petrogenetic links with granites, Guarda-Belmonte area, central PortugalPublication . Neiva, A.M.R.; Ramos, João FarinhaGranitic amblygonite-subtype and lepidolite-subtype, aplite-pegmatite sills intruded a biotite>muscovite granite (G1). Two other biotite>muscovite granites (G2 and G3) and a muscovite>biotite granite (G4) crop out in the area. Variation diagrams for major and trace elements of the Variscan rocks show fractionation trends for a) G1 and G4; b) G2, G3 and aplite-pegmatite sills. The two series are confirmed by the two trends defined by major elements of primary muscovite. The sills also contain Li-bearing muscovite, which has higher Mn, Li, F and paragonite contents and lower AlVI content than primary muscovite from G2, G3 and sills. All sills have pure albite and P2O5 content of K-feldspar and plagioclase increases in the series G2, G3 and sills. Beryl occurs in all sills, but lepidolite and a nearly pure petalite only occur in lepidolite-subtype sills, which are the most evolved sills. Primary topaz and amblygonite have a similar composition in all sills. Aplite-pegmatite sills contain cassiterite, which shows sequences of alternating darker and lighter zones. The former are richer in (Nb + Ta + Fe + Mn) than the latter. Manganocolumbite is common in all sills, but ferrocolumbite only appears in amblygonite-subtype sills and manganotantalite in lepidolite-subtype sills. The sills richest in Li contain reversely-zoned crystals with a homogeneous microlite core and a heterogeneous uranmicrolite rim. Least squares analysis of major elements shows that granite G3 and amblygonite-subtype and lepidolite-subtype aplite-pegmatite sills can be derived from granite G2 magma by fractional crystallization of quartz, plagioclase, K-feldspar, biotite and ilmenite. Modelling of trace elements shows good results for Sr, but magmatic fluids controlled the Rb and Ba contents of the aplite-pegmatite sills and probably also their Li, F, Sn and Ta contents and crystallization of lepidolite, cassiterite and Nb–Ta oxide mineral assemblage. Schorl from the lepidolite-subtype sills that cut granite G1 has higher Mg/(Mg + Fe) than schorl from metasomatised granite at sill walls and resulted from the mixing of magmatic fluids carrying B and some Fe with a meteoric fluid that has interacted with the host granite G1 and carried Fe and Mg. Schorl and dravite, respectively from metasomatised granite and micaschist at sill walls, were also formed from the mixing processes.