Browsing by Issue Date, starting with "2022-03-25"
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- O impacto da utilização de ecrãs na PHDA na infância e adolescênciaPublication . Rodrigues, Inês Sofia Morgado; Correia, Paula Cristina Moreira AntunesIntrodução: A Perturbação da Hiperatividade e Défice de Atenção (PHDA) é a patologia do neurodesenvolvimento mais diagnosticada na infância. Muitos estudos têm procurado respostas para a compreensão da sua fisiopatologia, tentando perceber como otimizar o diagnóstico, tratamento e também a sua prevenção. Também, a excessiva utilização de ecrãs pelos mais novos tem aumentado exponencialmente, sendo, consequentemente, a sua utilização alvo de mais investigação que procura perceber os seus efeitos. Objetivos: Perceber o impacto dos ecrãs nesta patologia, nomeadamente no que concerne o sono, sintomas, emoções, neurodesenvolvimento e hábitos de vida, é o objetivo primordial desta revisão sistemática da literatura selecionada. Materiais e Métodos: Como metodologia para a realização desta Revisão Sistemática, foi utilizada a ferramenta PRISMA 2015, sendo usados os motores de busca PubMed, Jama, Elsevir, NCBI e RESEARCH GATE para a seleção dos artigos relevantes. A pesquisa centrou-se nos artigos publicados entre janeiro de 2015 e março de 2021 em língua portuguesa e língua inglesa. Resultados: Foi encontrada uma relação modesta, mas não negligenciável, do agravamento dos sintomas da PHDA e o uso de ecrãs na infância, bem como uma influência negativa na qualidade do sono, hábitos de vida e emoções. Conclusões: Apesar da relação encontrada, verifica-se também uma falta de estudos longitudinais robustos que estabeleçam uma relação causal forte, constatando-se a necessidade premente de investigar mais para perceber como melhor diagnosticar, tratar e, acima de tudo, prevenir o agravamento dos sintomas de PHDA na infância, com o uso excessivo de ecrãs.
- Airports and Emergency Planning Measures Implemented to Prevent the Spread of COVID-19 and their EffectivenessPublication . Pavia, Alexandre Cristovão; Silva, Jorge Miguel dos ReisAirports are subject to numerous situations that can disrupt their normal operations. Given the impossibility of preventing disruptions, especially those of natural origin, emergency and contingency plans are the best tool airports have to react effectively and quickly to any event. In late 2019, emerged an infectious disease of uncertain cause named COVID-19. The high rate of transmissibility and the increasing number of cases worldwide forced governments to implement measures to restrict movement, such as confinements or border closures. These measures had a more than significant impact on the aeronautical sector, which was one of the most affected. Record lows were thus recorded in the number of flights made, leading to historic losses throughout aviation. In order to analyse the implementation of measures against COVID-19, interviews were conducted with experts as well as surveys of the general public (those who had travelled by air in 2021). Through this data collection, interesting conclusions were drawn, such as the fact that the most efficient measure was the mandatory use of masks, which was widely adopted worldwide, and the least cost-efficient measure was the temperature plug, which was eventually abolished at most airports over time. Although no single measure on its own was efficient enough to deal with the pandemic, tiered mitigation was considered efficient. Although there were peculiarities at each airport when the measures were implemented, there was a normalization of measures over time. Finally, although most airports already had sections in their contingency/emergency plans that dealt with "public health emergencies", they were not prepared to deal with a pandemic crisis like COVID-19.
- Relatório de Estágio - Futebol Clube de Famalicão, SADPublication . Maceiras, Tiago Leal; Ferraz, Ricardo Manuel PiresNo âmbito da Unidade Curricular “Estágio” do 2º Ciclo de Estudos em Ciências do Desporto – Treino Desportivo, na Universidade Beira Interior, foi realizado um estágio curricular na equipa profissional do Futebol Clube Famalicão - SAD. O presente documento pretende descrever todo o processo que ocorreu durante a época desportiva na minha área de intervenção. Cumulativamente, é também apresentado um trabalho de introdução à investigação que teve como propósito comparar os valores de média do tempo de jogo, distância de alta intensidade e valores de força nos isquiotibiais entre dois grupos de jogadores (lesionados e não lesionados) e analisá-los de forma longitudinal. Considerando os resultados obtidos, verificou-se não existirem diferenças significativas entre os dois grupos (atletas lesionados e não lesionados). No entanto, a análise longitudinal permitiu concluir que a ocorrência de um episódio de lesão é tendencialmente maior quando os valores de tempo de jogo, distância de alta intensidade e força são menores durante a época.
- Numerical Analysis of a Single Droplet Combustion: Jet-A1, N-Dodecane, N-HexadecanePublication . Dias, Francisco José Ramos; Silva, André Resende Rodrigues daThere has been an increase in concerns about the planet earth and its resources throughout the past decades. The dependency on fossil fuels created a critical dilemma since transportation is currently fueled by traditional, not sustainable power sources. The originated climate crisis on fossil fuels demands action from mankind, specifically concerning the research on alternative ways of fueling the current methods of transportation. The implementation of Biofuels in transportation encourages future scientists and engineers as a realistic option among other different paths constructed to develop sustainable fuels. The study of the injection, impinging, evaporation, and combustion allows the improvement of the burning characteristics assuming a specific fuel within a combustion chamber. These investigations of the combustion and evaporation procedures improve the burning droplet performance and thus reduce the emitted emissions under the same circumstances. This study intends to numerically simulate the single droplet evaporation and combustion of fuel droplets in a drop tube furnace (DTF) that has the capacity of varying the ambient temperature. The numerical approach simplifies the physical phenomena by employing an Eulerian-Lagrangian approach, considering a discrete and a continuous phase, which is further accomplished while running in a CFD software. The continuous phase is computed recurring to a turbulence modeling, while the dispersed phase is separately computed using the discrete phase model. The computation of the combustion phenomenon is deeply related to the evaporation of the discrete phase employing the non-premixed combustion provided by the operating software. There is a 2D planar simplification of the 3D axisymmetric experimental cylinder followed by the respective discretization of the mathematical equations and pressure-velocity coupling. This work numerically simulates the burning phenomenon of n-dodecane, jet fuel, and nhexadecane single droplets. The obtained results of the droplet size reduction relating to time display agreement with the d 2 law and respective experimentally obtained data. The acquired outcomes also allow the establishment of correlations between the combustion characteristics and the droplet physics properties, such as velocity, displaying a reduction of the droplet velocity alongside the shrink of the droplet diameter. This information is visible for different temperature environments and fuels, suggesting a physical association. Besides this interpretation, the imposed droplet initial velocity variations (1.0 m/s until 1.3 m/s) do not affect the combustion characteristics outcomes. This study demonstrates a precise relation between the ambient temperature of the drop tube furnace (DTF) and the improvement of the combustion process and burning properties. Additionally, the chemical composition of the fuels influences the combustion characteristics and their performances. Overall, the numerical performed simulation can be improved and thus approximate the implemented simulation to the occurring physical event, allowing the development of the additional knowledge in this thematic.
- Hybridization effect on mechanical properties of composite laminatesPublication . Monjon, Alice Marie Albina Michel; Reis, Paulo Nobre Balbis dosComposite materials are increasingly being used in the aeronautical industry. Although carbon fibers are the strongest and most used in the aeronautical sector, these fibers collapse quite suddenly due to their fragile nature leading to catastrophic damage. In order to minimize this effect, an alternative technique is used, which consists of combining these fibers with another less fragile type, such as Kevlar fiber, in order to obtain a material with a more ductile behavior. As the viscoelastic behavior is not much discussed in the available open literature, this work intends to study this mechanical property in several hybrid composites involving carbon, kevlar and glass fibers. For a better understanding of this phenomenon, the static behavior and tenacity of these materials were also studied. For this purpose, the effect of hybridization on flexural properties, interlaminar shear strength, creep and stress relaxation was studied in eighteen hybrid combinations combined with an epoxy matrix. It was observed that hybridization can create a more tenacious and balanced composite. The stacking sequence has a significant influence on the mechanical properties of laminates. As such, for all mechanical tests, carbon fibers are better in compression if hybridized with kevlar and better in tension if hybridized with glass. Glass fibers have always performed better under compression and kevlar fibers always perform better under tension, regardless of which other fiber they are hybridized to. With these positions in the laminate, the composites achieve greater tension and stiffness, but less deformation, greater interlaminar shear strength, less creep and less stress relaxation. As for the number of fiber layers, in the bending properties, a lower percentage of kevlar in the laminate results in higher bending stress and interlaminar shear strength. However, for the viscoelastic behavior of hybrid composites, the number of layers has no direct influence on the creep and stress relaxation values, since molecular rearrangements occur. In addition, a study of the bending properties for different strain rates in carbon fiber composites and fiberglass composites was carried out. In this way, it could be shown that there is a relationship between the strain rate and the flexural stress and stiffness of the composites. As the strain rate increases, there is an increase in bending stress and stiffness.