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- Acquisition of competencies in mathematics through gamesPublication . Ferreira, Maria Cristina; Pereira, José António; Oliveira, AmilcarThe objective of this paper is to present the fundamentals of game theory and illustrate how the theory can be applied in education of Mathematics.Literature specific applications of game theory across all levels of instructor-led education. With a game theory model, we provide a mathematical description of a social situation in which two or more individuals or players interact. We strongly suggestthat traditional teaching techniques of mathematics should be complemented with games.
- Actas do 1º Encontro de Observadores de Aves das Arribas do DouroPublication . Marcos, AdéritoLivro de actas do ArribAves 2003 - 1º Encontro de Observadores de Aves das Arribas do Douro, que se realizou no Solar dos Marcos, Bemposta, Mogadouro, 26-27 de Julho 2003.
- Actas do 1º Encontro do Mel das Arribas do Douro - ArribasMel 2004Publication . Marcos, AdéritoLivro de resumos do 1º Encontro do Mel das Arribas do Douro - ArribasMel 2004, realizado no Solar dos Marcos, Bemposta, Mogadouro, 27 de Março 2004.
- Adaptive complex diffusion noise despeckling for 3D OCT DataPublication . Bernardes, Rui; Maduro, Cristina; Serranho, Pedro; Dinis, João; Cunha-Vaz, JoséPurpose: To demonstrate the performance of a recently proposed despeckling filter when extended to 3D in OCT data. Methods: A new formulation for a complex diffusion filter was recently proposed [1] being adaptive in time and adjusting parameters to data, facilitating diffusion in the vitreous and reducing it in the retina to preserve tissue information. This new formulation outperformed, both quantitatively and qualitatively, currently existing filters, while at the same time was computationally more efficient attaining the same despeckling level in 34% of the computing time. We have now extended it to perform 3D OCT despeckling achieving a significant improvement in noise removal. We have resorted to a mathematical based synthetic OCT scan in order to assess quantitative results in 3D. In addition, we have applied this 3D filter to a set of 72 eye scans, from healthy volunteers (20), diabetic retinopathy (20), cystoid macular edema (2), age-related macular degeneration (20) and choroidal neo-vascularization (10), who underwent high-definition Cirrus OCT (Carl Zeiss Meditec, Dublin, CA, USA) using macular cube protocols (200x200x1024 and/or 512x128x1024). Results: The extension from 2D to 3D of this adaptive complex diffusion filter proved to be beneficial by achieving an increased level of noise reduction while simultaneously better preserving fundamental information. These facts are supported from well known metrics (e.g. MSE-mean squared error, ENL-effective number of looks and CNR-contrast-to-noise ratio) for the synthetic OCT scan and from the assessment made by 3 retina specialist who graded qualitatively the output of the 2D and 3D filters. Conclusions: These findings demonstrate this new formulation and its extension to 3D is beneficial for human analysis of OCT data and suggest it might be an important tool for automated data processing as in segmentation of retinal structures. [1] Bernardes R, Maduro C, Serranho P, Araújo A, Barbeiro S, Cunha-Vaz J. Improved adaptive complex diffusion despeckling filter. OPTICS EXPRESS 18(23):24048-24059, 2010.
- Adaptive recommendation in online environmentsPublication . Azambuja, Rogério Xavier de; Morais, A. Jorge; Filipe, VítorRecommender systems form a class of Artificial Intelligence systems that aim to recommend relevant items to the users. Due to their utility, it has gained attention in several applications domains and is high demanded for research. In order to obtain successful models in the recommendation problem in non-prohibitive computational time, different heuristics, architectures and information filtering techniques are studied with different datasets. More recently, machine learning, especially through the use of deep learning, has driven growth and expanded the sequential recommender systems development. This research focuses on models for managing sequential recommendation supported by session-based recommendation. This paper presents the characterization in the specific theme and the state-of-the-art towards study object of the thesis: the adaptive recommendation to mitigate the information overload in online environments.
- Addressing low dimensionality feature subset selection: reliefF(-k) or extended correlation-based feature selection(eCFS)?Publication . Tallón-Ballesteros, Antonio J.; Cavique, Luís; Fong, SimonThis paper tackles problems where attribute selection is not only able to choose a few features but also to achieve a low performance classification in terms of accuracy compared to the full attribute set. Correlation-based feature selection (CFS) has been set as the baseline attribute subset selection due to its popularity and high performance. Around hundred data sets have been collected and submitted to CFS; then the problems fulling simultaneously the conditions: a) a number of selected attributes lower than six and b) a percentage of selected attributes lower than a forty per cent, have been tested onto two directions.Firstly, in the scope of data selection at the feature level, some options proposed in a prior work as well as an advanced contemporary approach have been conducted. Secondly, the data pre-processed and initial problems have been tested with some sturdy classifiers. Moreover, this work introduces a new taxonomy of feature selection according to the solution type and the followed way to compute it. The test bed comprises seven problems, three out of them report a single selected attribute, another one with two extracted features and the three remaining data sets with four or five retained attributes, all of them by CFS; additionally, the feature set is between six and twenty nine and the complexity of the problems, in terms of classes, uctuates between two and twenty one, throwing averages of sixteen and around five for both aforementioned properties. The contribution concluded that the advanced procedure is suitable for problems where only one or two attributes are selected by CFS; for data sets with more than two selected features the baseline method is preferable to the advanced one, although the considered feature ranking method achieved intermediate results.
- Adipates as new phase change material: seeking for a low temperature energy storage systemPublication . Sequeira, Maria Carolina; Nogueira, Bernardo A.; Caetano, Fernando J. P.; Diogo, Herminio; Fareleira, João M. N. A.; Fausto, RuiThe recent and endless increasing need for energy is requiring imperative and efficient solutions. Renewable energies are an effective solution, but they are also intermittent, which often leads to a gap between the availability of energy and its demand. Therefore, energy storage becomes crucial for improving the efficiency by reducing the mismatch between demand and supply thus offering better management capabilities. The use of phase change materials (PCMs) became an attractive technology, especially for active cooling systems. In particular, eutectic systems can be designed for each application, allowing significant energy savings, which is very relevant in what concerns economic and environmental sustainability [1]. Equilibrium studies and their phase diagrams are crucial to characterize the behavior of these systems, particularly for new PCMs [2]. This work aims the characterization of a selected type of binary system composed by di-n-alkyl adipates that can be used for energy storage at low temperatures, starting by the construction of solid-liquid phase diagram based on Differential Scanning Calorimetry (DSC) and Raman Spectroscopy results. The studied system is a binary mixture of diethyl and dibutyl adipates and reveals to behave as a eutectic system at low temperatures, possessing also polymorphism, therefore presenting a relatively complex phase diagram. The eutectic point was found around -33ºC and the polymorphism transition, being characteristic of the dibutyl adipate, occurs at around -36ºC for the overall phase diagram. Raman spectroscopy was fundamental concerning the construction of the phase diagram, enabling to identify the different solid and liquid phases of the system. This work provides new phase equilibrium data, which, to the knowledge of the authors, are the first in the literature, concerning these compounds. The studied binary system has promising characteristics for low temperature energy storage. It is also demonstrated how solid-liquid-phase equilibrium studies are the key to select the most appropriate phase change material for a specific thermal energy storage (TES) application.
- Algumas técnicas SIG úteis à obtenção de áreas de serviço de conjuntos de pontosPublication . Tralhao, Lino; Rodrigues, João Coutinho; Sousa, NunoEm estudos de acessibilidade, e não só, são muito úteis um tipo de estruturas que se podem obter a partir de uma rede, eventualmente multi-modal e parametrizável: as chamadas “áreas de serviço”, as quais são constituídas por polígonos, cada qual correspondente a uma zona situada entre um certo intervalo de custo, relativamente a uma certa “feature” (ponto, multiponto, etc.). Pretende-se neste estudo obter, a partir de áreas de serviço relativas a um universo de features, áreas de serviço relativas a subconjuntos dessas features. Estas técnicas envolvem manipulações relativamente complexas de polígonos e podem ser generalizadas para conjuntos de conjuntos e assim sucessivamente. Convém notar que nem sempre se dispõe da rede, podendo dispor-se das referidas estruturas; eventualmente, no caso de áreas de serviço, sob a forma de imagens (raster) a serem convertidas para formato vectorial.
- Alterações climáticas, perceções e racionalidadesPublication . Viegas, Vanda; Azeiteiro, Ulisses; Dias, João Alveirinho; Alves, FátimaConsiderando que as Alterações Climáticas (AC) – uma das cinco áreas-guia da Estratégia 2020 da Comissão Europeia – são um problema global que requer respostas locais articuladas aos níveis macro, meso e micro; e que a sua compreensão implica a identificação das relações reciprocamente influentes entre a Natureza, a Sociedade e a Cultura; qualquer intervenção – seja no sentido da mitigação das AC, seja no sentido da adaptação às AC – envolve necessariamente essa mesma sociedade, em toda a complexidade das suas dimensões socioculturais e ambientais. Neste artigo, enquadrado pelas teorias compreensivas, refletimos brevemente sobre algumas das inter-relações entre os sistemas climáticos, ambientais e socioculturais e defendemos que as racionalidades leigas, por se enraizarem em tipos e fontes de saber plurais, são um dos pilares para melhor se compreender e lidar com o fenómeno das AC. Whereas Climate Change (CC) – one of the five prioritary areas of the Strategy 2020 of the European Commission – is a global challenge needing local responses, articulated at the macro, meso and micro levels; and while its understanding entails identifying mutually influential relationships between Nature, Society and Culture, any intervention – either to mitigate or adapt to CC – necessarily involves society itself, in the full complexity of its sociocultural and environmental dimensions. In a world in the midst of a major demographic transition, with a population expected to reach 9 billion by 2050, issues like sustainability, resource use, scarcity and sharing, have been interwoven in the international, regional and local arenas. This paper develops in the light of comprehensive theories. The methodological procedures are based upon desk research and all the work relies on the reflexive notion and today´s ubiquitous complexity. The spirit of this pivotal approach is the interest in knowledge, curiosity for different dimensions of knowledge and how it is (re)produced, articulated and reflected in the relationships of the individual human being, with itself, with other human beings, with other living creatures and with the environment. This papers argues that the lay rationalities, because they take root in various types and sources of knowledge, are one of the pillars to better understand and deal with the phenomenon of CC. Part one of this paper makes a brief reference to ethical implications, preceded by a succinct analysis of the key dynamics and processes, which are considered responsible for the variability and climate change in a diachronic perspective. Part two discusses some of the sustainability issues, with a brief introduction to the pathways and strategies for mitigating and adapting to CC, which have been outlined and lie ahead, linking the global dimension to the local dimension, governments to markets and to civil society. Finally, focusing on lay rationalities, a brief approach is sought regarding the issues of reflexivity, social capital and the ‘knowledge-power’ concept, keeping in mind that the study of the social reality, which is complex in nature, is always a (de)constructed exercise of dialectics between generalization and specialization.
- Amianto em Portugal: a difícil aplicação da Lei 2/2011Publication . Janela, José; Pereira, PedroPara fazer face a problemas de saúde ambiental provocados pelo amianto, o Parlamento Português aprovou a Lei 2/2011, visando a remoção de materiais com amianto existentes em edifícios públicos. Após consulta de documentos oficiais e entrevistas a responsáveis de entidades públicas e outros atores chave, demonstra-se que a lei só muito parcialmente foi cumprida. A maior parte da Administração Pública não estava preparada cientificamente nem tinha recursos humanos e financeiros suficientes para aplicar a legislação. O resultado foi um levantamento muito incompleto de edifícios com amianto. Só dois anos após o prazo previsto, e após grande pressão pública, com ampla e determinante cobertura mediática, se publicou uma primeira lista dos edifícios públicos com amianto em Portugal continental, não existindo ainda previsão do prazo de remoção total desse material.