Infrared stereolithography

Tese de doutoramento em Ciência e Engenharia de Polímeros e CompósitosStereolithography is an important rapid prototyping process that creates three-dimensional solid objects in a multi-layer procedure. This technology involves the curing or solidification of a liquid photo or thermo sensitive polymer through the use of an irradiation light source, which supplies the energy needed to induce a chemical reaction, bonding large numbers of small molecules and forming a highly cross-linked polymer. This reaction determines the resin morphology that, in turn, defines the physical, electrical, and mechanical properties of the cured material. The cure reaction is highly exothermic and, the temperature and the reaction rate can vary considerably within the curing material due to polymers low thermal conductivity. The main goal of this thesis is to study the process of microstereolithography by infrared radiation and the corresponding polymeric systems. Thermal effects were used over an appropriated polymeric resin to induce a phase change in the material, known as cure reaction, and consequently to obtain solid shapes or patterns. Cure kinetics was characterised and the effects of resin composition were determined. The knowledge of parameters and material composition influence over the process is of great importance to predict both the final geometry and mechanical properties.A estereolitografia é um importante processo de prototipagem rápida que permite criar objectos sólidos tridimensionais através de um processo camada a camada. Esta tecnologia envolve a cura ou solidificação de uma resina polimérica líquida, termo ou foto sensível através da utilização de uma fonte de irradiação, que fornece a energia necessária para provocar uma reacção química, ligando um grande número de pequenas moléculas e levando à formação de um polímero altamente reticulado. Esta reacção determina a morfologia de resina que, por sua vez, define as propriedades físicas, eléctricas e mecânicas do material curado. A reacção de cura é altamente exotérmica e a temperatura e velocidade da reacção podem variar consideravelmente no interior do material curado devido à baixa condutividade térmica dos polímeros. O objetivo principal deste trabalho é estudar o processo de micro estereolitografia por radiação infravermelha e os sistemas poliméricos correspondentes. Efeitos térmicos foram utilizados sobre uma resina polimérica apropriada para induzir uma mudança de fase no material, conhecido como reacção de cura, e, consequentemente, para obter formas ou padrões sólidos. A cinética da cura foi caracterizada e os efeitos da composição da resina foram determinados. O conhecimento da influência dos parâmetros e da composição do material no processo é de grande importância para prever a geometria final e as propriedades mecânicas

Residential Hybrid Ventilation Systems in Portugal:Experimental Characterization

Due to the variation in natural factors, such as wind speed and the stack effect, natural ventilation systems are unlikely to provide permanent ideal ventilation rates. As such, this paper will characterize the performance of hybrid ventilation systems that are a possible solution to this drawback. This project presents the experimental study characterizing the hybrid ventilation system in a 100- apartment residential complex in the Porto area. The results of the measurements of temperature, humidity, flow rates in ducts, ACH by the PFT technique and weather conditions taken in seven flats are presented

Modeling and simulation of photofabrication processes using unsaturated polyester resins

Several kinetic models have been proposed to simulate thermosetting cure reactions. The most complex models, based on a mechanistic approach of cure reactions, are developed based on the concepts of free radical polymerization and the mechanism of reactions with diffusion. However, mechanistic models are usually quite impractical for engineering purposes because of the difficulty in obtaining the model parameters. An alternative to these mechanistic models are the phenomenological models, formulated in terms of the degree of cure and much easier to apply. Phenomenological models have been largely used to study thermal-initiated cure reactions, although only few works used them to model the kinetics of ultraviolet-initiated cure reaction. This work proposes a photo-thermal-kinetic model to study the behavior of unsaturated polyester resins during ultraviolet-initiated cure reactions. The model considers samples with different amounts of initiator concentration and cure reactions performed under different ultraviolet light intensities. The model has been numerically solved using the finite element techniquePortuguese Foundation for Science and Technology; contract grant number: POCTI/EME/58405/2004

A multi-camera and multimodal dataset for posture and gait analysis

Monitoring gait and posture while using assisting robotic devices is relevant to attain effective assistance and assess the user’s progression throughout time. This work presents a multi-camera, multimodal, and detailed dataset involving 14 healthy participants walking with a wheeled robotic walker equipped with a pair of affordable cameras. Depth data were acquired at 30 fps and synchronized with inertial data from Xsens MTw Awinda sensors and kinematic data from the segments of the Xsens biomechanical model, acquired at 60 Hz. Participants walked with the robotic walker at 3 different gait speeds, across 3 different walking scenarios/paths at 3 different locations. In total, this dataset provides approximately 92 minutes of total recording time, which corresponds to nearly 166.000 samples of synchronized data. This dataset may contribute to the scientific research by allowing the development and evaluation of: (i) vision-based pose estimation algorithms, exploring classic or deep learning approaches; (ii) human detection and tracking algorithms; (iii) movement forecasting; and (iv) biomechanical analysis of gait/posture when using a rehabilitation device.This work has been supported by the Fundação para a Ciência e Tecnologia (FCT) with the Reference Scholarship under Grant 2020.05708.BD and under the national support to R&D units grant, through the reference project UIDB/04436/2020 and UIDP/04436/2020

Certificação sísmica das construções e perigosidade sísmica em Portugal

A análise dos efeitos dos sismos nas construções permite evidenciar, novamente, que as estruturas construídas de acordo com as modernas regulamentações para o dimensionamento sísmico de estruturas se comportam bem, sendo naquelas que não obedecem a estas regulamentações que se verificam os maiores danos e que originam um grande número de mortes. A necessidade de garantir que todas as novas estruturas, ou aquelas que vierem a ser reabilitadas ou reconstruídas, cumpram as prescrições previstas na regulamentação para as dotar de bom comportamento sísmico deve, assim, constituir uma preocupação essencial das sociedades que habitam zonas em que exista um significativo risco sísmico, como é caso de Portugal. Neste contexto, a Sociedade Portuguesa de Engenharia Sísmica (SPES) tem ao longo dos últimos anos vindo a desenvolver campanhas para sensibilizar os poderes políticos para a necessidade de certificar as construções existentes. Nesse sentido a SPES está a desenvolver metodologias para brevemente apresentar uma proposta para a certificação do comportamento sísmico das construções onde serão identificados os procedimentos que devem ser adotados para a certificação dos edifícios existentes. Acrescente-se, ainda, uma outra preocupação da SPES, relacionada com os diferentes mapas de perigosidade sísmica para Portugal continental que têm resultado de vários projetos nacionais e internacionais, e que traduzem níveis de perigosidade sísmica muito diferentes para algumas regiões do território português, particularmente para o sul de Portugal. A SPES, espelhando a inquietude existente na comunidade científica, considerou urgente e promoveu a realização de um estudo criterioso acerca das opções tomadas, nos diferentes estudos, de forma a tentar perceber os fatores que mais contribuíram para as diferenças evidenciadas.info:eu-repo/semantics/publishedVersio

Markerless gait analysis vision system for real-time gait monitoring

On this paper a vision-based contact and markerless method for gait evaluation is proposed, and validated in different experimental setups against commercial motion capture systems (Vicon) and inertial gait analysis tools (GaitShoes). While the development goal is its integration on the ASBGo Smart Walker platform, only an inexpensive depth camera is required. It is shown to have reasonable results when computing gait metrics in real time, in different experimental setups, from different walker types, vision hardware and walking scenarios. Performance is evaluated through RMSD values for several gait metrics. Results illustrate that the proposed approach can be a valuable non-invasive, contactless and low cost alternative to gait analysis systems used in clinical rehabilitation environments.This work has been supported by the FEDER Funds through COMPETE 2020 — Programa Operacional Competitividade e Internacionalizacão (POCI) and P2020 with the Reference Project EML under Grant POCI-01-0247-FEDER-033067; COMPETE 2020 — Programa Operacional Competitividade e Internacionalizacão (POCI) with the Reference Project under Grant POCI-01-0145-FEDER-006941

Prevalence, awareness and control of diabetes in Portugal: results from the first National Health Examination Survey (INSEF 2015)

A Diabetes Mellitus é uma grande ameaça para a saúde pública em todo o mundo, continuando a aumentar em prevalência e significado. As estimativas da sua prevalência, conhecimento e controlo são essenciais para monitorizar as suas tendências de forma efetiva. Neste contexto, foi realizado o primeiro Inquérito Nacional de Saúde com Exame Físico (INSEF) à população residente em Portugal, com idade compreendida entre os 25 e os 74 anos, em 2015. O INSEF consistiu num estudo transversal de prevalência, que incluía a medição do nível de HbA1c no sangue, um exame físico e uma entrevista geral de saúde. A prevalência geral de diabetes foi estimada em 9,9% (IC95%: 8,4; 11,5), sendo mais elevada nos homens do que nas mulheres (12,1% vs 7,8%). A diabetes era mais prevalente entre os indivíduos que apresentavam baixa escolaridade e sem atividade profissional. A maioria dos indivíduos diabéticos estava ciente de sua condição (87,1%) e encontrava-se a tomar medicação antidiabética (79,7%). Destes, 63,2% apresentaram níveis de HbA1c inferiores a 7,0%. A prevalência de diabetes permanece mais elevada do que as estimativas globais e europeias, embora haja maior conscientização e melhor controlo dos objetivos clínicos relacionados com esta doença crónica.Diabetes Mellitus is a major public health threat around the world, continuing to increase both in prevalence and significance. Estimates of its prevalence, knowledge and control are essential to monitor its trends ef fectively. In this contex t, the first National Health Examination Sur vey (INSEF) was per formed on the resident population in Por tugal aged between 25 and 74 years old, in 2015. The INSEF consisted of a crosssectional prevalence study, which included the measurement of the HbA1c level in the blood, a physical examination and a general health inter view. The overall prevalence of diabetes was estimated at 9.9% (95% CI: 8.4, 11.5), being higher in men than in women (12.1% vs 7.8%). Diabetes was more prevalent among individuals with low education level and without professional activit y. The majorit y of diabetic individuals were aware of their condition (87.1%) and were taking antidiabetic medication (79.7%). Of these, 63.2% had HbA1c levels lower than 7.0%. The prevalence of diabetes in Por tugal remains higher than the global and European estimates, although there is greater awareness and bet ter control of the clinical objectives related to this chronic disease.info:eu-repo/semantics/publishedVersio

Para o estudo da evolução do ensino e da formação em administração educacional em Portugal

Estudos sobre a evolução do ensino de disciplinas, na formação de professores em Portugal, são recentes. O controle burocrático centralizado reteve as dimensões do controle político-administrativo. De certo modo, protegeu a esfera educativa das influências modernizantes, do capitalismo industrial e das lógicas mercantis e gerencialistas. Defendeu a educação do domínio político, da intervenção de movimentos sociais, das propagandas de ideais democráticos e da cidadania. A utilização da designação "Administração educacional" ilustra as dificuldades sentidas, ao longo dos últimos anos, em termos da construção acadêmica de uma área, seja pela falta de tradição, seja pelos antecedentes históricos.In Portugal, studies about the evolution of disciplines teaching in the teachers formation are recent. The centralized bureaucratic control has held back the dimensions of politic administrative control. In a certain way, it has protected the education against the new-fashioned influences, manufacturing capitalism, and mercantile and managerial logics. This centralized bureaucratic control has also profected the education against the politic dominion, the intervention of social movements, the advertising of democratic ideals, and against the citizenship. The use of the term "Educational administration" shows the difficulties met by the searchers along the latest years, since there is no tradiction nor historic antecedence

Thrombus aspiration in patients with ST-elevation myocardial infarction: results of a national registry of interventional cardiology

BACKGROUND: We aimed to evaluate the impact of thrombus aspiration (TA) during primary percutaneous coronary intervention (P-PCI) in 'real-world' settings. METHODS: We performed a retrospective study, using data from the National Registry of Interventional Cardiology (RNCI 2006-2012, Portugal) with ST-elevation myocardial infarction (STEMI) patients treated with P-PCI. The primary outcome, in-hospital mortality, was analysed through adjusted odds ratio (aOR) and 95% confidence intervals (95%CI). RESULTS: We assessed data for 9458 STEMI patients that undergone P-PCI (35% treated with TA). The risk of in-hospital mortality with TA (aOR 0.93, 95%CI:0.54-1.60) was not significantly decreased. After matching patients through the propensity score, TA reduced significantly the risk of in-hospital mortality (OR 0.58, 95%CI:0.35-0.98; 3500 patients). CONCLUSIONS: The whole cohort data does not support the routine use of TA in P-PCI, but the results of the propensity-score matched cohort suggests that the use of selective TA may improve the short-term risks of STEMI..info:eu-repo/semantics/publishedVersio