Ciências e Tecnologia | Comunicações em congressos, conferências, seminários/Communications in congresses, conferences, seminars
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- 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.
- An actionable knowledge discovery system in regular sports servicesPublication . Pinheiro, Paulo; Cavique, LuísThis work presents an actionable knowledge discovery system for real user needs with three steps. In the first step, it extracts and transforms existing data in the databases of the ERP and CRM systems of the sports facilities and loads them into a Data Warehouse. In a second phase, predictive models are applied to identify profiles more susceptible to abandonment. Finally, in the third phase, based on the previous models, experimental planning is carried out, with test and control groups, in order to find concrete actions for customer retention.
- An energy-based pedestrian accessibility indicatorPublication . Sousa, Nuno; Moreira, Florbela; Rodrigues, João CoutinhoThis article presents an approach to pedestrian accessibility based on human effort rather than distance. By measuring effort as the muscular energy required to traverse network arcs with slopes, it is possible to derive an accessibility indicator that takes relief into account. A case study in the city of Coimbra, Portugal, shows that while relief does have a considerable impact on the accessibility thus measured, that impact is global and not local. When accessibility to all types of opportunities are considered, the influence of relief ultimately dilutes due to the geographical scattering of those opportunities.
- An experience of teaching biology classification and evolution in e-learning environmentPublication . Seixas, SóniaThis work describes the experience of teaching a university course “Biological Classification and Evolution”, in an e-learning environment, over two years. The pedagogical model adopted by our university and the platform used is Moodle. The course was divided into several units, each with written texts, films of YouTube and a forum to discuss the contents. This experience gave very positive feedback.