The University of Madeira dɐ mɐˈdɐjɾɐ], 32°39′32″N 16°55′28″W) is a Portuguese public university, created in 1988 in Funchal. It houses the following departments and autonomous sections. The university offers first and second cycle academic degrees in a wide range of fields, in accordance with the Bologna process. It is now under the CMU/Portugal agreement with Carnegie Mellon University, having master programme of Human Computer Interaction and Entertainment Technology. Students admitted will be eligible for scholarships and have internship opportunity during the summer break. In addition, Madeira Interactive Technologies Institute, founded in January 2010, is devoted to building international partnership with other educational institutes and industry. Wikipedia.
Nouri A.,University of Madeira |
Wen C.,Swinburne University of Technology
Critical Reviews in Solid State and Materials Sciences | Year: 2014
Mechanical alloying/milling technique is characterized by the repeated welding and fracturing of powder particles in a high-energy ball mill, which often results in excessive cold welding and agglomeration of ductile particles. To achieve the critical balance between cold welding and fracturing, the surface of the deforming particles is modified by introducing a suitable organic material, called surfactant or process control agent (PCA). However, the use of surfactants is self-contradictory by nature and requires further consideration of the milling variables and type/amount of surfactant. The current article provides a practical approach to the promises and challenges associated with surfactants in mechanical alloying/milling. An attempt has been made to address the most crucial aspects correlated with surfactants, including contamination, the morphology and size of powder particles, formation of alloy and microstructural evolution, and powder yield, as well as the physico-mechanical properties, such as magnetism, density, hardness, and compressive strength. An overview is also given on the adsorption mechanism of surfactants onto the surface of powder particles, with a special emphasis on type, amount, and the addition time of surfactants in the mechanical alloying process. © 2014 Copyright Taylor and Francis Group, LLC.
Barros J.D.,University of Madeira |
Silva J.F.,University of Lisbon
IEEE Transactions on Industrial Electronics | Year: 2010
This paper presents an optimal predictive controller for a multilevel converter-based dynamic voltage restorer (DVR), which is able to improve the voltage quality of sensitive loads connected to the electrical power network. The optimal predictive controlled multilevel DVR can restore sags and short interruptions while reducing the total harmonic distortion (THD) of the ac line voltages to values lower than 1%. The DVR is based on a three-phase neutral point clamped converter to dynamically inject a compensation voltage vector in series with the line voltage, through series-connected transformer secondary windings. To assure high-quality voltages for sensitive loads, we devise optimal predictive control laws for the injected compensation ac voltages. A suitable quadratic weighed cost functional is used to choose the voltage vector, minimizing both the ac voltage errors through current injection and the dc side capacitor voltage unbalancing. The performance of the proposed predictive controller is compared to classical proportional integral (PI): synchronous frame and stationary frame (P $+$resonant) controllers. The line-side filter capacitor topology is compared to the regular converter-side filter capacitor. Obtained experimental results show that the ac voltages are almost sinusoidal in steady-state operation when facing balanced and unbalanced sags and short interruptions with unbalanced loads. Voltage THD is reduced to values lower than 1%; the DVR is behaving also as a series active power filter for the ac voltages. © 2006 IEEE.
Agency: European Commission | Branch: FP7 | Program: CSA-SA | Phase: FP7-PEOPLE-2013-NIGHT | Award Amount: 106.98K | Year: 2013
This proposal aims to raise awareness of the prominent role researchers and how their work plays in our currently every day and for the future. Bearing in mind Horizon 2020 Societal Challenges, the ERN2013 will promote and disseminate what in terms of science and innovation is being done in Portugal. The extensive and nationwide range of activities already planned and being prepared have one major aim: to show that researchers are ordinary people with extraordinary jobs! This will be done through direct engagement of both the general public and researchers in science awareness, across 26 main cities and villages in several venues. Coordinated by Cincia Viva (Lisbon), there is a regional coordinator in each NUTS II region in Portugal. The role of each regional coordinator is to mobilize the research community, local companies and associations, as well as regional/local press, using the same coordination rational from 2012. This is an inclusive proposal welcoming all interest research-related entities. The key message agreed between partners and all associated/participating entities is that we should take up this opportunity to bring research close to the people and not only expect that people come to a specific venue. Outdoor activities will be organized in partnership with municipalities/regional authorities as an added value of their service and a way to show the richness existing in each territory. In parallel, a very diverse range of edutainment indoor activities is planned and more are on the making.
Agency: European Commission | Branch: FP7 | Program: CSA-SA | Phase: FP7-PEOPLE-2012-NIGHT | Award Amount: 160.46K | Year: 2012
This proposal aims to raise awareness of the prominent role researchers and their work play in our everyday life. The extensive and nationwide range of activities already planned and being prepared have one major aim: to show that researchers are ordinary people with extraordinary jobs! This will be done through direct engagement of both the general public and researchers in science awareness activities, across the streets of 22 main cities and villages. Coordinated by Cincia Viva (Lisbon), there is a regional coordinator in each NUTS II region in Portugal. The role of each regional coordinator is to mobilize the research community, local companies and associations, as well as regional/local press. This is an inclusive proposal welcoming all interested research-related entities. The key message agreed between partners and all associated/participating entities is that we all should take up this opportunity to bring research close to the people and not only expect that people come to a specific venue. Outdoor activities will be organized in partnership with municipalities/regional authorities as an added value of their service and a way to show the richness existing in each territory. In parallel, a very diverse range of edutainment indoor activities is planned (see Annex I) and more are on the making.
Barros J.D.,University of Madeira |
Silva J.F.A.,Center for Innovation in Electric and Energy Engineering |
Jesus E.G.A.,University of Madeira
IEEE Transactions on Industrial Electronics | Year: 2013
The development of high-processing-capability microprocessors allows the implementation of new digital control methods for neutral-point-clamped (NPC) multilevel converter in power-electronic applications. This paper presents a new predictive digital control method for multilevel converters, called fast predictive. This method computes the optimal vector using the NPC three-phase multilevel dynamic model equations just once in each control cycle, while current predictive methods need 27 calculations. The closest vector to the optimal vector is found by minimizing the distance between each one of the 27 available vectors to the optimal vector. Space vector modulation could be also used. The obtained performance is similar to the predictive optimal control that uses the converter model to find all the 27 responses of the multilevel and then searches for the vector that minimizes control errors. Relative to predictive optimal control, the fast predictive improves digital processing speed by at least 150% in multilevel converters with 27 vectors. This speed improvement would allow multilevel converters with five or higher number of levels (125 instead of 27 vectors) to be controlled using the same sampling frequency of the three-level inverter. The fast-predictive controller is used in a multilevel rectifier with near-unity power factor to enforce the ac currents. Fast predictive control is also used in the rectifier dc voltage to reduce sensitivity of the dc voltage to dc load disturbances. The simulation and experimental results show that the fast-predictive controller is able to control the ac currents of a three-phase multilevel rectifier, achieving nearly 1.5% total harmonic distortion while balancing the capacitors' dc voltages. The use of predictive control to regulate the dc voltage shows an improvement of approximately 7% compared to a proportional-integral controller. © 2012 IEEE.
Azevedo J.A.R.,University of Madeira
IEEE Transactions on Antennas and Propagation | Year: 2011
The circular symmetry of concentric ring arrays becomes an advantage for situations where the radiation patterns are symmetric in the azimuthal direction. For planar arrays with elements in an equispaced grid, the fast Fourier transform can be applied in the calculations involved between the array factor and the source distribution. However, for circular arrays the elements are in a non-equispaced grid, making the application of fast computation algorithms difficult. Therefore, two techniques are proposed to synthesize circular arrays. The first one provides the control of the pattern by sampling the array factor. In this case, the fast Fourier transform can be applied. The windows technique is also utilized to control the sidelobe levels and the ripple structure of the shaped beam. The second technique considers the symmetric nature of concentric circular arrays and the control of the array factor is performed imposing some specific points of the pattern. © 2010 IEEE.
Benilov M.S.,University of Madeira
Journal of Physics D: Applied Physics | Year: 2010
The conventional model of near-cathode space-charge sheath with ions entering the sheath from the quasi-neutral plasma may not be applicable to discharges burning in cathode vapour, e.g. vacuum arcs, where ionization of emitted atoms may occur inside the sheath with some of the produced ions returning to the cathode and others moving into the plasma. In this connection, a simple model is considered of a sheath formed by electrons and positive ions injected into the sheath with a very low velocity and moving from the sheath into the plasma. It is shown that such a sheath is possible provided that the sheath voltage is equal to or exceeds approximately 1.256kTe/e. This limitation is due to the space charge in the sheath and is in this sense analogous to the limitation of ion current in a vacuum diode expressed by the Child-Langmuir law. The ions leave the sheath and enter the plasma with a velocity equal to or exceeding approximately 1.585uB. © 2010 IOP Publishing Ltd.
Benilov M.S.,University of Madeira
Plasma Sources Science and Technology | Year: 2014
A new class of stationary solutions in the theory of glow discharges and plasma-cathode interaction in ambient-gas arc discharges has been found over the past 15 years. These solutions exist simultaneously with the solution given in textbooks, which describes a discharge mode with a uniform or smooth distribution of current over the cathode surface, and describes modes with various configurations of cathode spots: normal spots on glow cathodes, patterns of multiple spots recently observed on cathodes of glow microdischarges and spots on arc cathodes. In particular, these solutions show that cathode spots represent a manifestation of self-organization caused by basic mechanisms of the near-cathode space-charge sheath; another illustration of the richness of the gas discharge science. As far as arc cathodes are concerned, the new solutions have proved relevant for industrial applications. This work is dedicated to reviewing the multiple solutions obtained to date, their systematization, and analysis of their properties and physical meaning. The treatment is performed in the context of general trends of self-organization in bistable nonlinear dissipative systems, which allows one to consider glow discharges or arc-cathode interaction within a single physically transparent framework without going into mathematical details and offers a possibility of systematic computation of the multiple solutions. Relevant computational aspects and experimental data are discussed. © 2014 IOP Publishing Ltd.
Aleksandrova N.,University of Madeira
International Journal of Engineering Science | Year: 2012
Continuous stress-displacement solution to thin rotating solid disk problem is obtained for elastic-perfectly plastic material. The solution follows the classical approach based on equation of motion, Hooke's law, yield criterion, and conditions of continuity of stresses and/or displacement at the elastic/plastic boundary. It is shown that both the displacement field derived from the flow rule associated with Mises yield criterion and the stress distributions are continuous at the elastic/plastic boundary in contrast with the discontinuous solution based on Tresca yield criterion and its associated flow rule. © 2011 Elsevier Ltd. All rights reserved.
Gouveia S.C.,University of Madeira |
Castilho P.C.,University of Madeira
Food Research International | Year: 2012
Cynara cardunculus var. scolymus (artichoke) and Cynara cardunculus var. ferocissima (Madeira cardoon) are two Asteraceae plants used in Madeira Archipelago in diet and also for medicinal issues. The present work aimed to compare the phenolic composition and quantify the main compounds of these two plants and two artichoke-based dietary supplements (juice and dragées). The methanolic extract of the endemic plant cardoon was basically composed of caffeoylquinic acid isomers. The same compounds were observed in artichoke extract, where there was a larger number and variety of other phenolic compounds. Variations in qualitative and quantitative composition of the three artichoke based products were extensive, with only 3 components being common to all 3 products. Mono-O-diglycosilated flavonoids (luteolin, apigenin and quercetin) were found in the artichoke products but not in Madeira cardoon. 1,3-O-dicaffeoylquinic acid (cynarin), usually considered mainly responsible for the biological properties of artichoke, was found in high amounts ranging in most samples but was not detected in the analyzed commercial dragées. The antioxidant assays results reflected the highly diversified composition of the artichoke-based products, showing a high radical scavenger and reducing capacities, while the extract from Madeira cardoon was a poor antioxidant. © 2012 Elsevier Ltd.