Browsing by Issue Date, starting with "2009-08"
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- Reactive versus Latching Phase Control of a Two-body Heaving Wave Energy ConverterPublication . Falcão, António F. de O.; Justino, Paulo Alexandre; Henriques, João C.C.; André, José M.C.S.The paper deals with the modelling, optimization and control of the IPS buoy wave energy converter, a two-body point-absorber oscillating in heave, consisting of a floater rigidly connected to a long submerged vertical acceleration tube open at both ends within which a piston can slide, forcing the motion of the inside water below and above it. Energy is converted from the relative motion between the piston and the buoy-tube pair. The modelling is performed in the frequency domain (including reactive phase control), in order to provide some kind of geometry optimization, and also in the timedomain to allow the simulation of a more realistic highpressure- oil power take-off system.
- Indium crystal chemistry : from thin-fill materials to natural bulk chalcogenidesPublication . Figueiredo, M. Ondina; Silva, Teresa
- High-tech element availability for sustainable energy systems in the 21st century :the Iberian Pyrite Belt as a potential supplierPublication . Reiser, Fiona K. M.; de Oliveira, Daniel Pipa Soares; Rosa, DiogoThis work provides estimations on the future raw material demand for the thin-film photovoltaic (PV) elements indium, selenium, tellurium, germanium and gallium. Data calculation has been carried out on the basis of current energy and PV market outlooks. For indium, our calculation yields a maximum cumulative demand of 12 kilotons for the period from 2008 to 2030. The minimum demand for the same period is of 8 kilotons. Additionally, static depletion times for the elements in question have been determined. For indium, the static depletion time of 22 years shows that its supply is highly endangered, particularly if indium consumption for LCD and solar panel production stays on a high level or even increases. The situation for selenium, with a static depletion time of 53 years, is not much better. Therefore, in addition to recycling, the fundamental way to enhance material supply is through intensified exploration for mineral deposits. Such exploration could focus in promising areas, where high-technology elements are already known to exist in sulphide ore deposits, e.g. the Iberian Pyrite Belt (IPB), a metallogenic province known for its massive sulphide ore resources.
- The binding state of indium in natural chalcogenides : a XANES approach through the L.3 absorption edgePublication . Figueiredo, M. Ondina; Silva, Teresa
- The Hirnantian stratigraphy of Portugal, with notes on the Trás-os-Montes and Valongo-Arouca areasPublication . Sá, Artur Abreu; Pinto de Meireles, Carlos Augusto; Piçarra, José Manuel; Vaz, Nuno; Gutiérrez-Marco, Juan Carlos
- High-tech element availability for sustainable energy systems in the 21st century : The Iberian Pyrite Belt as a potential supplierPublication . Reiser, Fiona K. M.; Rodrigues, Carlos; de Oliveira, Daniel Pipa Soares; Rosa, DiogoThis work provides estimations on the future raw material demand for the thin-film photovoltaic (PV) elements indium, selenium, tellurium, germanium and gallium. Data calculation has been carried out on the basis of current energy and PV market outlooks. For indium, our calculation yields a maximum cumulative demand of 12 kilotons for the period from 2008 to 2030. The minimum demand for the same period is of 8 kilotons. Additionally, static depletion times for the elements in question have been determined. For indium, the static depletion time of 22 years shows that its supply is highly endangered, particularly if indium consumption for LCD and solar panel production stays on a high level or even increases. The situation for selenium, with a static depletion time of 53 years, is not much better. Therefore, in addition to recycling, the fundamental way to enhance material supply is through intensified exploration for mineral deposits. Such exploration could focus in promising areas, where high-technology elements are already known to exist in sulphide ore deposits, e.g. the Iberian Pyrite Belt (IPB), a metallogenic province known for its massive sulphide ore resources.
- The Bragança Podiform Chromite Field in NE PortugalPublication . de Oliveira, Daniel Pipa Soares; Santana, Helena; Pinto de Meireles, Carlos Augusto; Guimarães, Fernanda
- Blue pigments in XVI-XVII century glazes : a comparative study between portuguese faiences and contemporary chinese porcelains manufactured for portuguese marketPublication . Figueiredo, M. Ondina; Silva, Teresa; Veiga, JP; Prudêncio, M. Isabel; Dias, M. Isabel; Matos, Maria Antónia; Pais, Alexandre Manuel
- Brazilian castor oil as raw material for biodiesel productionPublication . Lages, Cléia; Araújo, Eduardo; Oliveira, Ana Cristina
- Combined biologic removal of sulphate for tanning industrial wastewatersPublication . Di Berardino, SantinoA biologic pretreatment technology of mixed tanneries wastewater, suitable for sulphate-rich industrial wastewaters, has been studied, in order to eliminate chemical precipitation and improve removal efficiency of the relevant pollutants. It couples an anaerobic reactor with an aerobic sulphide oxidant (ASO) step, where H2S2 is partially oxidized to elemental sulphur, and includes a recirculation system. The proposed solution provided Methanogenic Archae (MA) and Sulphate Reducing Bacteria (SRB) coexistence and controlled inhibition by partial oxidation of hydrogen sulphide.. The removal effiency of the anaerobic reactor was quite dependent on temperature and hydaulic retention time (HRT). COD removal varied between 32-68 % and sulphate removal (20-60%), referred to the mixture of the industrial effluent diluted with 50% of recirculation, at an Organic Load (OL) ranging from 0.5 to 1.5 kg CODM³ d⁻¹ and HRT from 1 to 5 days. The entire biologic pretreatment (AHF+ASO) resulted much more efficient and COD removal increased to 64-82% being less dependent on temperature variations. This process removed also a significant part (85%) of Chromium (Cr⁺³), by sorption into the biologic sludge. This two step biologic pretreatment, ensured better removal of relevant parameters than conventional chemical precipitation, avoided addition of chemical products, minimized excess sludge production, and also removed hydrogen sukphide and sulphate, resulting in a favorable alternative solution. The effluent from this stage was submitted to a sequencing batch nitrification/denitrification step, to improve the removal of the relevenat parameters. The average removal efficiency of entire process was appreciable and better than the conventional solution: COD = 88%, Sulphate = 68% and Nitrogen (kjeldahl) = 92%, chromium (Cr⁺³=96%). However, the presence of non degradable organic compounds delivered in the effluent from syntetic tanning, were hard to remove completely and did not allow fulfilling the severe standards for wastewater discharge in water course in terms of COD, Nitrogen (kjeldahl) and color. This requires and additional polishing step