Repositório RCAAP

Comunicação apresentada em Powerpoint, composta por 12 slides

Comunicação apresentada em Powerpoint, composta por 16 slides

This article analyzes the process of construction of a new innovation system based on wind energy in a "follower" context. The technological innovation systems framework is used to analyze and explain the emergence of a new wind industry in Portugal, where this renewable energy technology knew a spectacular development in the past decade. This framework highlights the main processes or functions that intervene in the diffusion of a new technology. The evidence obtained demonstrates that the fulfillment of these functions, which were mostly studied in the context of pioneer countries, is still pertinent to explain the formation of a wind energy system in this follower country. Yet the type of resources and the nature of the activities needed to adopt the technology in the latter will often differ. This case provides new insights about the importance of functions that enhance the follower's capacity to assimilate the new technology (e.g. local knowledge development, experimentation), creating conditions for a fast move as soon as innovations become sufficiently mature in the core.

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Cooling rates based on the retrograde diffusion of Fe2+ and Mg between garnet and biotite inclusions commonly show two contrasting scenarios: a) narrow closure temperature range with apparent absence of retrograde diffusion; or b) high result dispersion due to compositional variations in garnet and biotite. Cooling rates from migmatites, felsic and mafic granulites from Ribeira Fold Belt (SE Brazil) also show these two scenarios. Although the former can be explained by very fast cooling, the latter is often the result of open-system behaviour caused by deformation. Retrogressive cooling during the exhumation of granulite-facies rocks is often processed by thrusting and shearing which may cause plastic deformation, fractures and cracks in the garnet megablasts, allowing chemical diffusion outside the garnet megablast – biotite inclusion system. However, a careful use of garnets and biotites with large Fe/Mg variation and software that reduces result dispersion provides a good correlation between closure temperatures and the size of biotite inclusions which are mostly due to diffusion and compositional readjustment to thermal evolution during retrogression. Results show that felsic and mafic granulites have low cooling rates (1–2 °C/Ma) at higher temperatures and high cooling rates (~100 °C/Ma) at lower temperatures, suggesting a two-step cooling/exhumation process, whereas migmatites show a small decrease in cooling rates during cooling (from 2.0 to 0.5 °C/Ma). These results agree with previously obtained thermochronological data, which indicates that this method is a valid tool to obtain meaningful petrological cooling rates in complex high-grade orogenic belts, such as the Ribeira Fold Belt.

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Conferência final do projecto Building SPP

Conferência final do projecto Building SPP

Conferência final do projecto Building SPP

Conferência final do projecto Building SPP

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This paper focuses on the five parameters modeling, consisting on a current controlled generator, single-diode, a shunt and series resistances. Also, a simulation, identification of the parameters for a photovoltaic system and the maximum power point tracking based on VP„g„g is presented. The identification of parameters and the performance of the equivalent circuit model for a solar module simulation are validated by data measured on the photovoltaic system.

Magnetic resonance sounding (MRS) provides quantitative hydrogeological information on hydrostratigraphy and hydraulic parameters of subsurface (e.g. flow and storage property of aquifers) that can be integrated in distributed hydrologic models. The hydraulic parameters are typically obtained by pumping tests. In this study, we propose an MRS integration method based on optimizing MRS estimates of aquifer hydraulic parameters through hydrologic model calibration. The proposed MRS integration method was applied in the 73 km2 Carrizal Catchment in Spain, characterized by a shallow unconfined aquifer with an unknown aquifer bottom. 12 MRS survey results were inverted with Samovar 11.3, schematized and integrated in the transient, distributed, coupled, hydrologic, MARMITES-MODFLOW model. As the aquifer bottom was unknown, the aquifer was schematized into one unconfined layer of uniform thickness. For that layer, MRS estimators of specific yield and transmissivity/hydraulic conductivity were calculated as weighted averages of the inverted MRS layers. The MRS integration with hydrologic model was carried out by introducing multipliers of specific yield and transmissivity/hydraulic conductivity that were optimized during transient model calibration using 11 time-series piezometric observation points. The optimized multipliers were 1.0 for specific yield and 3.5*10-9 for hydraulic conductivity. These multipliers were used, and can be used in future MRS investigations in the Carrizal Catchment (and/or adjacent area with similar hydrogeological conditions), to convert MRS survey results into aquifer hydraulic parameters. The proposed method of MRS data integration in the hydrologic model of Carrizal Catchment not only allowed us to calibrate the model but also to confirm the functional capability of MRS in quantitative groundwater assessment. Most importantly however, it demonstrated that if pumping tests are not available, the use of MRS integrated in distributed coupled hydrological models, or even in standalone groundwater models, provides a valuable aquifer parameterization alternative.

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European Geosciences Union General Assembly 2009 (EGU 2009), Vienna, Austria, April 19-24, 2009

European Geosciences Union General Assembly 2008 (EGU 2008), Vienna, Austria, April 13-18, 2008

ABSTRACT: With the expected increase of lithium demand in the forthcoming years, an efficient management of all the available resources is necessary. Rock minerals like pegmatites are important primary sources of lithium that shall be valorized. Minero-metallurgical processes have been developed for lithium recovery from pegmatitic ore deposits, involving physical concentration, thermal treatment, digestion and/or leaching in order to obtain a lithium soluble species adequate to produce lithium carbonate by precipitation. Physical concentration by froth flotation or by optical sorting are the two main alternative operations to produce a Li concentrate. Metallurgical treatment starts by calcination where the silicate structure is transformed to a more reactive solid phase (ß-spodumene). Afterwards digestion with sulfuric acid and water leaching allows the dissolution of lithium sulfate. Carbonate pressure leaching is an alternative technology for treating pegmatites and production of lithium carbonate. Energy and chemicals savings is crucial in order to reduce the high costs associated with metallurgical processing of Li rock minerals.  

Resumos das comunicações apresentadas nas jornadas realizadas na Batalha - Porto de Mós, de 11 a 13 de Setembro de 2014

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