Browsing by Issue Date, starting with "2019-11"
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- Thoughts on Machiavelli de Leo StraussPublication . Bento, AntónioEm 1975, Harvey Mansfield e John Pocock, dois eminentes especialistas norte-americanos no pensamento político de Maquiavel, travaram-se de razões numa violenta discussão acerca do valor e do significado, para a compreensão histórica de Maquiavel e do “maquiavelismo”, do famoso e polémico livro de Leo Strauss Thoughts on Machiavelli (1958). Este debate entre Mansfield e Pocock foi publicado na prestigiada revista Political Theory (Vol. 3, Nº 4, November 1975). Ao exumarmos e reconstituirmos agora, com alguma demora e minúcia, os principais passos e argumentos de ambos os autores em torno da interpretação straussiana de Maquiavel, o nosso propósito é dar a conhecer ao público de língua portuguesa os termos de uma controvérsia – tão viva quanto instrutiva – que espelha ainda hoje a prodigiosa fortuna e o tremendo impacto da obra de Maquiavel na nossa contemporaneidade.
- New index for sustainability in climate control - TWI (Total Water Impact)Publication . Santos, Alexandre F.; Gaspar, Pedro DinisSales for air conditioning are growing rapidly in buildings, more than tripling between 1990 and 2016. This energy use for air conditioning comes from a combination of rising temperatures, rising population and economic growth. Energy demand for climate control will triple by 2050, consuming more energy than the United States, the European Union and Japan today. This increase in energy will directly impact water consumption, either to cool a condenser of equipment directly or to serve indirectly as a basis for energy sources such as hydroelectric power that feed into these HVAC systems. Knowing the unique and growing importance of water, a new index, Total Water Impact (TWI) is presented, which allows a holistic comparison of the impact of water use on water, air and evaporative condensation climate systems.
- Active and intelligent packaging - Principles of operation, characteristics and applicationsPublication . Rato, Nuno; Gaspar, Pedro DinisFood preservation is a topic increasingly being discussed due to market needs, where food from all over the world is required under the best chemical and physical conditions, with minimal waste. Active packaging is defined as the deliberate addition of some components to enhance the properties of the packaging. The various types of active packaging are oxygen scavengers, carbon dioxide emitters and absorbers, ethylene absorbers, ethanol emitters, moisture absorbers, and antimicrobial agents. Smart packaging includes indicators that provide information on product quality and safety over time, such as packaging history, inside and outside atmosphere, oxygen levels, among others. Given the demands on food safety and quality as well as product traceability, there is an exponential increase in the development, production and use of active and intelligent packaging.
- SocialNetCrawler: Online Social Network CrawlerPublication . Pais, S.; Cordeiro, João; Martins, Ricardo; Albardeiro, Miguel Ângelo SerraThe emergence and popularization of online social networks suddenly made available a large amount of data from social organization, interaction and human behavior. All this information opens new perspectives and challenges to the study of social systems, be- ing of interest to many fields. Although most online social networks are recent, a vast amount of scientific papers was already published on this topic, dealing with a broad range of analytical methods and applications. Therefore, the development of a tool capable of gather tailored information from social networks is something that can help a lot of researchers on their work, especially in the area of Natural Language Processing (NLP). Nowadays, the daily base medium where people use more often text language lays precisely on social networks. Therefore, the ubiquitous crawling of social networks is of the utmost importance for researchers. Such a tool will allow the researcher to get the relevant needed information, allowing faster research in what really matters, without losing time on the development of his own crawler. In this paper, we present an extensive analysis of the existing social networks and their APIs, and also describe the conception and design of a social network crawler which will help NLP researchers.
- Fault-Tolerant Back-to-Back Converter for Direct-Drive PMSG Wind Turbines Using Direct Torque and Power Control TechniquesPublication . Jlassi, Imed; Cardoso, A. J. M.Fault tolerance in wind turbines is considered crucial to increase their reliability and availability levels. This paper presents a fault-tolerant direct-drive permanent magnet synchronous generator (PMSG) using new direct control techniques, with the ability to handle power semiconductor open-circuit faults in the full-scale back-to-back converter. The fault-tolerant topology consists of a five-leg converter, with a shared leg connected to a generator phase and to its corresponding grid phase, through a triode for alternating current (TRIAC). The main contribution of this paper consists of the development of an alternative direct torque control and direct power control schemes for both machine-side converter and grid-side converter, respectively. Moreover, a reliable fault diagnostics algorithm without requiring additional sensors is also integrated, providing the information required to instantaneously trigger fault-tolerant remedial strategies. Simulation and experimental results are presented to validate the effectiveness of the proposed fault-tolerant PMSG drive.
- Máscaras da VenerePublication . Herberto, LuísEste artigo é estruturado em pertinentes citações visuais da pintura de Tiziano, Venere di Urbino, obra icónica do imaginário erótico renascentista que se revelou um catalisador formal e conceptual para artistas de gerações futuras, destacando aqui os portugueses Acácia Maria Thiele e Gabriel Abrantes, entre outras referências obrigatórias no palco artístico europeu. As suas obras são aqui interpretadas numa esfera de raíz activista, quer na objectificação do corpo feminino, quer na camuflagem social que igualmente propõem, apesar de algumas inevitáveis interferências, resultante de conceitos e abordagens menos consensuais.
- Optimal Fuel Saving in 4D Waypoint NetworksPublication . Ahmed, Kawser; Coelho, Milca; Bousson, K.The purpose of this work is to develop a trajectory optimization method that generates a fuel optimal trajectory from a predefined 4D waypoint networks, where the arrival time is specified for each waypoint in the network. A single source shortest path algorithm is presented to generate the optimal flight trajectory that minimizes fuel burn. Generating such trajectories enables the airlines to cope with increasing fuel costs and to reduce aviation induced climate change, as emission is directly related to the amount of fuel burn. Two case studies were considered and the simulation results showed that flying a fuel optimal trajectory based on the proposed algorithm leads to a reduction of average fuel consumption on international flights by 2-4% compared with the conventional trip fuel.
- Resultados preliminares de deteção de imagens de pêssegos aplicando o método Faster R-CNNPublication . Assunção, Eduardo Timóteo; Gaspar, Pedro Dinis; Mesquita, Ricardo; Veiros, André; Proença, H.A deteção de frutos é de fundamental importância em sistemas de estimação de produção. Neste trabalho, são apresentados os resultados preliminares da utilização do método de deteção de objetos Faster R-CNN na deteção de imagens de pêssegos. O estudo consiste na avaliação do desempenho do método em imagens RGB obtidas em ambiente real num pomar. Embora este método de deteção tenha sido aplicado noutros trabalhos com o objetivo de detetar frutos, ainda não foi utilizado na deteção de pêssegos. A cor, a sua distribuição na árvore e a clusterização são características intrínsecas aos pêssegos. Os resultados obtidos, ainda que preliminares, mostram um elevado potencial da utilização do método na deteção destes frutos. Todavia, os resultados também mostram a necessidade de melhoria no desempenho. Isso pode ser alcançado com o aumento na quantidade de imagens de treino e também por definir um melhor critério de anotação dos frutos oclusos.
- Decision support system to assign food price rebates on the basis of quality declinePublication . Maciel, Vinicius Biasutti Pitol; Matos, Cláudia; Lima, Tânia M.; Gaspar, Pedro Dinis; Santos, Fernando CharruaIn order to reduce food waste, fruits and vegetables in special, in small and medium markets sizes, caused by loss of quality at the end of shelf life, an appropriate pricing method was created to maximize profit of seller. The method it was based on an acquisition of primary data, through questionnaires appropriate to the theme, and, subsequently, these primary data was used for mathematical modeling using a pricing dynamic method. As a last step this work, was development a spreadsheet application, where the seller can found a ideal point of order, size of stock and best price to sell. This way, using the application, the goal of reduction of food waste in fruit products is expected.
- Preliminary results of peach detection in images applying convolutional neuronal networkPublication . Assunção, Eduardo Timóteo; Proença, H.; Veiros, André; Mesquita, Ricardo; Gaspar, Pedro DinisThe fruit detection part is very important for a good performance in a yield estimation system. This paper presents the preliminary results using the object detection Faster R-CNN method in the peaches images. The aim is evaluate the method performance in the detection of peach RGB images. Images acquired in an orchard were used. Although this method of object detection has been applied in other studies to detect fruits, according to the literature, it has not been used to detect peaches. The results, although preliminary, show a great potential of using the method to detect peach.