Browsing by Issue Date, starting with "2021-10"
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- Testing of a resistive sensor with fabric medium for monitoring frost formation in refrigeration systemsPublication . Aguiar, Martim; Gaspar, Pedro Dinis; Silva, Pedro D.; Duarte, DianaRefrigeration is one of the key elements for food preservation. With global temperatures increasing due to global warming, the efficiency in refrigerated storage systems must be improved. One of the problems that is yet to be solved in these systems is the efficient and accurate removal of the frost formed on the heat exchanger surface. In previous works, a low-cost resistive sensor has been developed to detect frost formation for accurate removal. This paper shows the results of an experimental study carried out to increase the accuracy, by placing different configurations of a fabric medium in between the sensor electrodes.
- An insight on B2B Firms in the Age of Digitalization and Paperless ProcessesPublication . Oliveira, José; Azevedo, António; Ferreira, João José de Matos; Gomes, Sofia; Lopes, JoãoIn recent years and due to market demand and environmental regulations, firms have been changing their procedures regarding document production, handling, and filling. There has been a paradigm change in document sustention in order to attain such changes, from paper-based to electronic forms, resulting in the Digitization and Paperless Office Program (DPOP). The literature on digitization and paperless processes is profuse; nonetheless, it is outdated, uses only single or multiple case study approaches, and is limited to specific industries, such as healthcare or higher education. To overcome this gap, this research analyses the current implementation of the DPOP in five major sectors by using a country scale approach; consequently, this research study contributes to strengthening the literature in this area of knowledge. The methodology used is quantitative and is based on a questionnaire distributed to the most important economic sectors (education, health, trade, industry, and services) in Portugal. The results show that a DPOP positively impacts companies, as it increases profitability and, in most cases, is a sine qua non condition for negotiating with clients. Additionally, it favours companies’ image, reduces costs, and contributes to environmental sustainability. This research provides new insights into how firms using a DPOP may contribute to dematerialization and paper consumption reduction. It is also original as it covers multiple sectors using a country approach.
- Molecular Beacon Assay Development for Severe Acute Respiratory Syndrome Coronavirus 2 DetectionPublication . Carvalho, Josué; Nunes, J. Lopes; Figueiredo, Joana; Santos, Tiago; Miranda, André; Riscado, Micaela; Sousa, Fani; Duarte, A. P.; Socorro, Sílvia; Tomaz, Cândida; Felgueiras, Mafalda; Teixeira, Rui; Faria, Conceição; Cruz, CarlaThe fast spread of SARS-CoV-2 has led to a global pandemic, calling for fast and accurate assays to allow infection diagnosis and prevention of transmission. We aimed to develop a molecular beacon (MB)-based detection assay for SARS-CoV-2, designed to detect the ORF1ab and S genes, proposing a two-stage COVID-19 testing strategy. The novelty of this work lies in the design and optimization of two MBs for detection of SARS-CoV-2, namely, concentration, fluorescence plateaus of hybridization, reaction temperature and real-time results. We also identify putative G-quadruplex (G4) regions in the genome of SARS-CoV-2. A total of 458 nasopharyngeal and throat swab samples (426 positive and 32 negative) were tested with the MB assay and the fluorescence levels compared with the cycle threshold (Ct) values obtained from a commercial RT-PCR test in terms of test duration, sensitivity, and specificity. Our results show that the samples with higher fluorescence levels correspond to those with low Ct values, suggesting a correlation between viral load and increased MB fluorescence. The proposed assay represents a fast (total duration of 2 h 20 min including amplification and fluorescence reading stages) and simple way of detecting SARS-CoV-2 in clinical samples from the upper respiratory tract.
- SDSim: A generalized user friendly web ABM system to simulate spatiotemporal distribution of species under environmental scenariosPublication . Bioco, João; Cánovas, Fernando; Prata, Paula; Fazendeiro, PauloThis paper presents the Agent-Based Modelling System of spatial distribution of species SDSim. SDSim is an agent-based modelling system designed to simulate spatial distribution of species and populations for conservation and management purposes. SDSim gives to modellers the ability to simulate movements and colonization patterns of species given locations under study and a set of eco-geographical variables in which species depends on.
- Exploration of the Age-Category Soccer Performance Effects During Ball Possession Small-Sided GamesPublication . Nunes, Nuno André; Gonçalves, Bruno; Fenner, Jonathan SJ; Owen, Adam Lee; Travassos, BrunoSmall-sided games have been adopted as an integral part of soccer training, however, the use of task constraints by the coach and the action capabilities of both players and teams require further investigation. The aim of this investigation was to explore the age-category effects (under-11: U11, under-15: U15 and under-23: U23) on external training workloads (total distance covered, distance covered while walking, running and sprinting, number of sprints and maximum sprint speed), internal training load metrics (rate of perceived exertion, RPE) and tactical individual actions (passing number with dominant and non-dominant foot, and max passing speed) during 4 vs. 4 ball possession small-sided game constrained within three different playing areas (small: 20 x 15 m, medium: 25 x 20 m, and large: 30 x 25 m). Results revealed substantial differences (all p < .001) for each specific playing area observed across many of the external workload measures. For every area analysed, U23 players covered more distance walking, whereas U11 and U15 players covered more distances at higher intensities. Additionally, significant differences were found for the RPE (small playing area: p = .001; large playing area: p < .001) with U23 and U15 players showing higher scores compared with U11 ones. It can be concluded that a 4 vs. 4 ball possession small-sided game can provide different performance related stimuli to players, depending on age category and the playing surface area. Therefore, coaches and individuals involved with training and development of soccer players across all age groups should be aware of the key variables highlighted in this study before planning training drills
- Desenvolvimento de manipulador e garra robótica destinados à recolha de frutos em aplicações agrícolasPublication . Tavares, Nuno Miguel da Silva; Gaspar, Pedro Miguel de Figueiredo Dinis OliveiraCada vez mais a agricultura carece de mão-de-obra, devido ao êxodo das zonas rurais para as zonas urbanas, aliada a um crescente envelhecimento da população mundial. Como o setor agrícola é fundamental à subsistência de todos, não pode parar, a introdução da robótica em determinadas atividades como a colheita de frutos, controlo de infestantes, monitorização, poda, pulverização, manuseamento de solos, navegação autónoma, entre outras, é vista como um contributo da tecnologia a este setor. Na presente dissertação apresenta-se o dimensionamento assim como todas as fases de construção de uma garra robótica desenvolvida para a recolha de frutos caídos no chão de um pomar. Esta atividade visa contribuir para a redução da perda alimentar por via da economia circular, podendo estes frutos caídos serem usados para alimentação animal. Por outro lado, a sua recuperação reduz a potencial carga microbiana e de insetos, e consequentemente nas doenças e pragas que podem ter origem nessa perda, na campanha seguinte. O protótipo foi projetado para ser acoplado ao manipulador cartesiano da plataforma robótica, o que requereu uma análise ao envelope de trabalho do manipulador a fim de determinar os requisitos dimensionais máximos da garra. Mediante os vários aspetos recolhidos sobre as várias garras robóticas expostas na revisão bibliográfica, foi elaborada uma matriz de decisão, de forma avaliar quais as especificações técnicas mais relevantes para a garra robótica. A garra foi modelada tridimensionalmente por via de desenho assistido por computador que permitiu gerar o modelo destinado à impressão 3D por deposição de material fundido, neste caso PLA, utilizada na construção do protótipo. O controlo e comando da garra residiu num microcontrolador da família Arduino, no qual se encontravam ligados os sensores relativos aos limites do envelope de trabalho, pinos de comando do movimento, e os servos motores e motores DC que procederam à movimentação da garra. Foram realizados ensaios experimentais para avaliar o desempenho da garra na recolha de frutos, dependendo da inclinação da plataforma robótica, em duas posições de recolha de frutos (central e lateral). Face aos resultados obtidos, verifica-se que a garra desenvolvida cumpre os objetivos para os quais foi desenvolvida.
- Modelação computacional do comportamento térmico de uma estufaPublication . Lebre, Bruno Miguel Carapito; Silva, Pedro Nuno Dinho Pinto da; Pires, Luis Carlos CarvalhoA necessidade de produção de todo o tipo de plantações em elevadas quantidades e ao longo de todo o ano faz do setor da agricultura um dos principais consumidores energéticos. A otimização deste consumo é essencial para garantir a sustentabilidade do mesmo. A implementação de estufas é uma estratégia que permite garantir as necessidades de produção, assim como possui grande potencial para otimização do processo. Nesta dissertação foram estudadas estas estruturas com recurso à simulação computacional. O primeiro passo foi a construção do modelo computacional, seguido da sua validação através da comparação com dados experimentais já existentes, e por fim uma série de estudos de caso foram realizados para avaliar os efeitos de diferentes parâmetros construtivos e operativos no comportamento térmico da estufa. Os resultados obtidos mostraram que a utilização de envidraçados de várias camadas e a variação da taxa de renovação do ar interior produziram os resultados com maior impacto. Estas técnicas permitem reduzir significativamente o consumo energético destas estruturas, promovendo a sua sustentabilidade.
- Sistemas Não Cooperativos para Registo de Assiduidade em Ambiente de Sala de AulaPublication . Fonseca, Alexandre Daniel Ramos; Proença, Hugo Pedro Martins Carriço; Inácio, Pedro Ricardo MoraisOver the years, high school dropout, college dropout, in particular, has always been a hot topic. With the advancement of technology and Artificial Intelligence and Machine Learning, we necessarily have to think of ways to help mitigate this problem. If there are factors that we cannot control, such as the economic ones, there are others where our actions can be directed. One factor that allows us to evaluate the risk of dropping out of school is student attendance. Although this data can be manually analyzed to make these detections, it would be more efficient to have a capable system of recording this attendance, since the human capacity to analyze data is finite, and often can only infer this situation too late. Of course, a system that only registers attendance will not give a definitive answer, but it will be an essential first step. Thus, a system that can reconcile the detection of a subject and his face while being able to constantly monitor where the subject is, always to be able to identify him even if he moves from one place to another, together with facial recognition, seem to be determining factors to bring a system of this calibre to a successful conclusion. This type of system is generally very much related to the quality of the data and its annotations, so it is vital to collect or obtain quality data to help solve the various problems presented. Considering what has been described, the main goal of this dissertation is to try to start solving the problem of school dropout, namely through the study, validation and testing of several stateoftheart methods in the area of object detection, namely people and faces, but also tracking. The same work will have to be done on face recognition methods, being able to indicate the best stateoftheart methods for each task. As mentioned in the previous paragraph, a significant limitation to this type of task is the data quality since it is not always possible to find a set that perfectly fits our context. Thus, to solve this gap, we will also present a dataset with about 40,000 images, thoroughly annotated frame by frame and that we believe to be an asset in solving this problem. In addition to the above, and in order not only to give a more meaningful and targeted response to our detailed data but also to provide a preliminary view of how one of the system’s tasks might work, we will present two experiments with our data in the area of detection. The first will involve finetuning our data, while the second will involve training it from scratch and then presenting its results as proof of the correct choice of the stateoftheart method.
- Poly(2-ethyl-2-oxazoline) functionalized reduced graphene oxide: Optimization of the reduction process using dopamine and application in cancer photothermal therapyPublication . Sousa, Ana Rita Lima; Alves, Cátia; Melo, Bruna L.; Moreira, André; Mendonça, António; Correia, I.J.; Diogo, Duarte de MeloThe high near infrared (NIR) absorption displayed by reduced graphene oxide (rGO) nanostructures renders them a great potential for application in cancer photothermal therapy. However, the production of this material often relies on the use of hydrazine as a reductant, leading to poor biocompatibility and environmental-related issues. In addition, to improve rGO colloidal stability, this material has been functionalized with poly(ethylene glycol). However, recent studies have reported the immunogenicity of poly(ethylene glycol)-based coatings. In this work, the production of rGO, by using dopamine as the reducing agent, was optimized considering the size distribution and NIR absorption of the attained materials. The obtained results unveiled that the rGO produced by using a 1:5 graphene oxide:dopamine weight ratio and a reaction time of 4 h (termed as DOPA-rGO) displayed the highest NIR absorption while retaining its nanometric size distribution. Subsequently, the DOPA-rGO was functionalized with thiol-terminated poly(2-ethyl-2-oxazoline) (P-DOPA-rGO), revealing suitable physicochemical features, colloidal stability and cytocompatibility. When irradiated with NIR light, the P-DOPA-rGO could produce a temperature increase (ΔT) of 36 ◦C (75 μg/mL; 808 nm, 1.7 W/cm2, 5 min). The photothermal therapy mediated by P-DOPA-rGO was capable of ablating breast cancer cells monolayers (viability < 3%) and could reduce heterotypic breast cancer spheroids' viability to just 30%. Overall, P-DOPA-rGO holds a great potential for application in breast cancer photothermal therapy.
- A pandemia e o jornalismo de checagem Casos Lupa (Brasil) e Polígrafo (Portugal)Publication . Borges, Fátima Regina de Oliveira; Correia, João Carlos FerreiraA disseminação de fake news tem atingido diferentes camadas da sociedade e encontrou nas redes sociais um potencializador. Essa realidade foi verificada na pandemia causada pelo vírus da Covid-19. O aparecimento do vírus provocou um aumento no número de informações falsas no Facebook, Twitter, Instagram e Whatsapp. A maioria dos países puderam sentir a interferência dessas falsas informações nos seus programas de controle da doença e do vírus. Em países como o Brasil, governos populistas e negacionistas aproveitaram para atuar diretamente em grupos de apoio, tornando ainda mais difícil o controle da pandemia em algumas regiões. Governos desse tipo apostam desde o início na desinformação e na minimização da doença, via notícias falsas ou duvidosas. Ao mesmo tempo, surgem instrumentos verificadores que desmentem essas informações, como as agências de factchecking. Diante desse quadro, esta pesquisa procura mostrar, como essas notícias falsas são controladas ou desmentidas nesses dois países. Para isso, tomaram-se a agência de factchecking, Lupa (Brasil) e o Jornal Polígrafo (Portugal). A intenção era mostrar de que forma esses dois canais minimizaram os estragos da disseminação das informações distorcidas.