Seleção da tecnologia mais eficiente para instalações refrigeradas sem temperaturas negativas para potências até 250 kW

Estágio de natureza profissional para obtenção do grau de Mestre em Engenharia Mecânica.A realização do presente trabalho passou por determinar a tecnologia mais eficiente para a conservação de produtos frutícolas com temperaturas positivas e com potências frigoríficas até 250 kW. Desta forma apresentaram-se soluções industriais para preservar determinados bens de primeira necessidade através de ciclos termodinâmicos nomeadamente, ciclos de compressão de vapor, tendo em consideração que são os mais utilizados na conservação alimentar. A seleção dos fluidos frigorígenos para combater as alterações climáticas passa por adotar fluidos naturais, fluidos HFO e misturas HFC-HFO com reduzido GWP e nulo OPD. Relativamente à análise de produtos frutícolas, evidenciou-se que a produção de laranjas apresentou um crescimento gradual entre 2016 e 2021 de 21,5 %, pelo que exibiu a segunda maior produção em 2021 com 363 918 t. A produção deste fruto encontra-se focalizada na região do Algarve com 77,6%, tendo sido este o fruto selecionado para conservar. Estudos realizados à operacionalidade dos sistemas de compressão simples permitiram observar o impacto que os mesmos têm sobre a eficiência energética. Realizaram-se análises ao impacto das temperaturas de condensação, das temperaturas de evaporação, dos sobreaquecimentos útil e não útil, do subarrefecimento e dos múltiplos estágios de compressão. Construiu-se um sistema aplicável para determinar qual o fluido mais eficiente tanto energética com exergeticamente. Inferiu-se que o sistema aplicável com o fluido R-717 apresenta-se como a melhor solução com um de 3,38 (4,44 com o adiabático em funcionamento). Para além disso o funcionamento do sistema aplicável com R-717 exibiu a menor energia destruída com 47,0 kW (29,5 kW com adiabático). Para as condições de funcionamento impostas para a conservação de laranjas, as propriedades termodinâmicas do R-717 destacam-se sobre os outros fluidos analisados. Os custos de investimento e de manutenção com a utilização do R-717 foram os mais acessíveis. No dimensionamento da instalação refrigerada inferiu-se que, para a área das câmaras de conservação e para o número apresentado de trabalhadores, não existem restrições à quantidade de R-717 utilizado no sistema. Concluiu-se, através da realização de um balanço térmico, que é possível conservar uma quantidade aproximada de laranjas de 104,37 t.The realization of the present work involved determining the most efficient technology for the conservation of fruit products at positive temperatures and with refrigerating powers of up to 250 kW. In this way, industrial solutions were presented to preserve certain essential goods through thermodynamic cycles, namely, steam compression cycles, taking into account that they are the most used in food preservation. The selection of refrigerants to combat climate change involves adopting natural fluids, HFO fluids and HFC-HFO blends with low GWP and zero OPD. Regarding the analysis of fruit products, it was evidenced that the production of oranges showed a gradual growth between 2016 and 2021 of 21.5%, so it exhibited the second highest production in 2021 with 363,918 t. The production of this fruit is focused on the Algarve region with 77.6%, and this was the fruit selected for conservation. Studies carried out on the operation of simple compression systems allowed observing the impact they have on energy efficiency. Analyzes were carried out on the impact of condensing temperatures, evaporation temperatures, useful and non-useful superheating, subcooling and multiple stages of compression. An applicable system was built to determine which fluid is the most efficient both energetically and exergetically. It was inferred that the system applicable with the fluid R-717 presents itself as the best solution with a of 3.38 (4.44 with the adiabatic in operation). Furthermore, the operation of the applicable system with R-717 exhibited the lowest exergy destroyed with 47.0 kW (29.5 kW with adiabatic). For the operating conditions imposed for the conservation of oranges, the thermodynamic properties of R-717 stand out over the other fluids analyzed. Investment and maintenance costs with the use of R-717 were the most affordable. In the dimensioning of the refrigerated installation, it was inferred that, for the area of the conservation chambers and for the number of workers presented, there are no restrictions on the charge of R-717 used in the system. It was concluded, by carrying out a thermal balance, that it is possible to preserve an approximate quantity of oranges of 104.37 t.N/

Arquitetura para a infância : o projeto como redutor do acidente

Mestrado Integrado em ArquitecturaExame público realizado em 18 de Abril de 2017A arquitetura escolar suscita uma preocupação em sistematizar conceitos, bem como as estratégias do projeto aparecem como uma ferramenta de apoio à conceção do edifício escolar, dando ênfase ao tamanho e aos padrões de habitabilidade do espaço físico edificado. Tradicionalmente, os edifícios escolares seguem um programa de necessidades previamente estabelecidas pelas secretarias da educação, no entanto, uma abordagem participativa no processo de conceção e nas várias etapas do programa arquitetónico pela comunidade educativa – crianças, professores, funcionários, familiares…- vai fomentar a partilha dos saberes e experiências daqueles que vivenciam os espaços, além de incorporar a reflexão sobre o perfil da instituição pretendida. Considerando que todas as crianças, bem como todos os profissionais ligados à educação infantil, passam em média um terço do seu dia no interior da creche/jardim de infância, a qualidade desses edifícios afeta significativamente a vida dos seus usuários. No presente trabalho pretendemos demonstrar que apesar de uma razoável evolução na escolha e aplicação de materiais, na escolha e aplicação da cor, na estruturação dos espaços de vivência dos utentes, ainda existem muitos aspetos onde o acidente pode acontecer com alguma facilidade. Dentro das melhorias que podemos implementar no processo, temos a possibilidade de adotar uma “politica de prevenção”, ao invés de uma “politica de correção”, executada nos programas de manutenção. Assim, as análises e conclusões realizadas nos edifícios para a infância possibilitam-nos clarificar a importância que tem uma correta elaboração do espaço arquitetónico, no seu todo, para a prevenção do acidente, bem como no desenvolvimento integral da criança.The school architecture raises a concern to systematize concepts and the design of strategies appear as a tool to support the design of the school building, emphasizing the size and habitability standards of physical space built. Traditionally, school buildings follow a needs program previously established by the departments of education, however, a participatory approach in the design process and the various stages of the architectural program for the educational community - children, teachers, staff, family ... - will foster sharing of knowledge and experiences of those who experience the spaces and incorporates reflection on the profile of the desired institution. Whereas all children and all professionals involved in early childhood education, spend on average one third of their day inside the nursery / kindergarten, the quality of buildings significantly affect the lives of its users. In this paper we intend to show that despite reasonable progress in the selection and application of materials, the choice and application of color, in the structuring of living spaces of users, there are still many aspects where the accident can happen with some ease. Within the improvements we can implement the process, we are able to adopt a "policy of prevention," rather than a "correct policy", performed in maintenance programs. Thus, the analysis and conclusions made in buildings for children enable us to clarify the importance of proper preparation of architectural space as a whole, for the prevention of accidents as well as the integral development of the child

A network Data Envelopment Analysis to estimate nations’ efficiency in the fight against SARS-CoV-2

The ongoing outbreak of SARS-CoV-2 has been deeply impacting health systems worldwide. In this context, it is pivotal to measure the efficiency of different nations’ response to the pandemic, whose insights can be used by governments and health authorities worldwide to improve their national COVID-19 strategies. Hence, we propose a network Data Envelopment Analysis (DEA) to estimate the efficiencies of fifty-five countries in the current crisis, including the thirty-seven Organisation for Economic Co-operation and Development (OECD) member countries, six OECD prospective members, four OECD key partners, and eight other countries. The network DEA model is designed as a general series structure with five single-division stages – population, contagion, triage, hospitalisation, and intensive care unit admission –, and considers an output maximisation orientation, denoting a social perspective, and an input minimisation orientation, denoting a financial perspective. It includes inputs related to health costs, desirable and undesirable intermediate products related to the use of personal protective equipment and infected population, respectively, and desirable and undesirable outputs regarding COVID-19 recoveries and deaths, respectively. To the best of the authors’ knowledge, this is the first study proposing a cross-country efficiency measurement using a network DEA within the context of the COVID-19 crisis. The study concludes that Estonia, Iceland, Latvia, Luxembourg, the Netherlands, and New Zealand are the countries exhibiting higher mean system efficiencies. Their national COVID-19 strategies should be studied, adapted, and used by countries exhibiting worse performances. In addition, the observation of countries with large populations presenting worse mean efficiency scores is statistically significant.info:eu-repo/semantics/publishedVersio

A Thermodynamic Assessment of the Cyber Security Risk in Healthcare Facilities

Over the last decades a number of guidelines have been proposed for best practices, frameworks, and cyber risk assessment in present computational environments. In order to improve cyber security vulnerability, in this work it is proposed and characterized a feasible methodology for problem solving that allows for the evaluation of cyber security in terms of an estimation of its entropic state, i.e., a predictive evaluation of its risk and vulnerabilities, or in other words, the cyber security level of such ecosystem. The analysis and development of such a model is based on a line of logical formalisms for Knowledge Representation and Reasoning, consistent with an Artificial Neural Networks approach to computing, a model that considers the cause behind the action

Influence of water and nutrients on cork oak radial growth – looking for an efficient fertirrigation regime

Abstract The widespread cork oak (Quercus suber L.) mortality and reduced afforestation /regeneration are causing an overall reduction in cork production. To enhance trees’ growth and vitality, afforestation techniques using fertirrigation were tested. The main objective was the promotion of trees’ growth on new dense plantations using minimum water requirements until reaching productive forests. The experimental plot – Irricork – was installed in 2017 in a ≈1 ha stand with 14 years’ age cork oaks summer-fertirrigated since plantation. Four fertirrigation treatments were applied during fertirrigation campaigns. Radial growth, meteorological parameters and fertirrigation volume were measured every 15–30 days over four years. It was observed that weather, tree size, debarking and trees’ intra-competition had a significant effect on radial increments. Fertirrigation significantly enhanced growth during summer drought and decoupled increments from air vapor pressure deficit constraints. There was a linear relationship between trees’ radial increments and fertirrigation volume up to 140 m3 week–1. Above this value, increments were smoother. In conclusion, summer fertirrigation of 140 m3 week–1 efficiently enhanced the radial growth of trees with 50–75 circumference at breast height, under the particular edaphoclimatic conditions of the stand. This study showed to be, therefore, promising in the use of efficient fertirrigation the enhance cork oaks’ radial growth

Terão os adolescentes portugueses uma alimentação adequada? : resultados do estudo HBSC de 2018

Revista de Psicologia da Criança e do Adolescente. - ISSN 1647-4120. - V. 10, n. 1 (Janeiro-Dezembro 2019). - p. 139-148.O objetivo do estudo foi caracterizar os hábitos alimentares e perceções relativas ao corpo dos adolescentes portugueses. Participaram no estudo, integrado no Health Behaviour in School aged Children, 6997 adolescentes portugueses (51,7% meninas) do 6º, 8º e 10º ano. Os adolescentes foram inquiridos acerca do seu peso, altura, hábitos alimentares e perceção de imagem corporal. Cerca de 70% dos adolescentes apresenta peso normal/saudável. Mais meninas do que rapazes considera a sua cintura “larga” e o seu corpo “gordo”. Cerca de 45% e 33% dos adolescentes reportaram consumir diariamente frutas e vegetais respetivamente. O consumo de doces e colas apresentou uma tendência crescente ao longo da escolaridade e as meninas referiram consumir estes alimentos com mais frequência que os rapazes. O consumo excessivo de açúcar juntamente com o consumo escasso de frutas e vegetais revelam fragilidades na alimentação dos adolescentes portugueses.The aim of this study was to characterize the eating habits and body image perceptions of Portuguese young people. A total of 6997 Portuguese young people (51.7% girls) attending the 6th, 8th and 10th grades participated in the study, integrated in the Health Behaviour in School aged Children. Young people were asked about their weight, height, eating habits and body image perception. About 70% of the adolescents presented normal/healthy weight. More girls than boys considered their waist “large” and that their body “fat”. Approximately 45% and 33% of the adolescents reported daily consumption of fruits and vegetables respectively. Consumption of sweets and soft drinks showed an increasing tendency between the 6th and 10th grades and girls reported consuming these foods more frequently than boys. Excessive consumption of sugar together with the scarce consumption of fruits and vegetables reveals frailties in the diet of Portuguese young

A heterogeneous computer vision architecture: implementation issues

The prototype of a heterogeneous architecture is currently being built. The architecture is aimed at video-rate computing and is based on a message passing MIMD topology at the top level-transputer based-and on VLSI associative processor arrays (APA, SIMD structure) for low level image processing tasks. The APA structure is implemented through a set of 4 VLSI chips (GLiTCH) containing 64 1-bit processing elements each. This communication addresses some issues concerning the implementation of the first prototype, namely those related to: • the design and integration of the APA controller unit, which provides the required interface between the APA, the MIMD topology and the video image interface: • the evaluation of the GLiTCH chip through an emulator based on transputers and fast programmable devices; the emulator was designed to be flexible enough to evaluate later modifications to the GLiTCH design; • the design of an integrated set of software development tools containing a structured editor-syntax oriented, with a visual interface/programming interface-and a cross compiler and debugger

Project-Based Learning: implementação no primeiro ano de um curso de Engenharia

As instituições de ensino superior estão cada vez mais preocupadas com a necessidade de implementar práticas de ensino e de aprendizagem centradas no estudante. Os métodos tradicionais de ensino, baseados exclusivamente em aulas expositivas, têm se revelado pouco eficazes para promover o desenvolvimento e formação global dos nossos estudantes. As crescentes exigências do mercado de trabalho, que procuram um perfil profissional não só baseado em competências técnicas de uma determinada área de conhecimento, mas antes uma variedade de competências transversais, como o trabalho em equipa, a resolução de problemas, a responsabilidade, gestão do tempo, criatividade, inovação, resiliência, etc. exigem que as universidades se aproximem da realidade e prática profissional dos futuros graduados, criando oportunidades para a cooperação e desenvolvimento de projetos interdisciplinares. Adicionalmente, a estrutura tradicional de organização em disciplinas que as isola em si mesmo e que não permitem ao aluno ter uma visão sistémica dos problemas, visão esta tão necessária no contexto profissional, requer mudanças ou abordagens que obriguem o aluno a ter esta visão sistémica e holística. Este livro apresenta a metodologia de Project-based Learning (PBL) ou Aprendizagem baseada em Projeto, desde a sua fase de preparação até à sua implementação num curso de Engenharia. Nesse sentido, visa constituir-se como um recurso de apoio a todos os interessados em implementar PBL, nos seus contextos de ensino e de aprendizagem. Apresenta uma descrição detalhada das etapas e procedimentos necessários para a preparação, definição, arranque, execução e finalização do processo PBL, partindo da realidade de um contexto concreto, nomeadamente, o curso de Mestrado Integrado em Engenharia e Gestão Industrial (MIEGI), da Escola de Engenharia da Universidade do Minho, Portugal

Descrição de um novo foco endêmico de esquistossomose mansônica no Estado de São Paulo, Brasil

A new endemic focus of schistosomiasis mansoni in the town of Bebedouro, S. Paulo, Brazil, is described. Two hundred and twenty-one cases are analyzed according to sex, age, and origin (autochthonous or not), the factors involved in the emergence of the focus are discussed and the necessity for control measure is emphasized.Foi descrito novo foco endêmico de esquistossomose mansônica situado na Cidade de Bebedouro, Estado de São Paulo, Brasil. Foram analisados 221 casos diagnosticados da doença segundo a idade, sexo e origem (autóctone ou não), bem como foram discutidos os fatores envolvidos no aparecimento do foco, alertando-se para a necessidade de medidas de controle

Sex bias in biopsy samples collected from free-ranging dolphins

Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in European Journal of Wildlife Research 56 (2010): 151-158, doi:10.1007/s10344-009-0299-7.Biological samples of free-ranging dolphins are increasingly used to gain information on population structure and ecology. In small cetaceans, the gender of individuals usually cannot be determined at sea, and population sex ratio has to be inferred indirectly. We used molecular sexing to determine the gender of 340 biopsy samples of bottlenose dolphins, Tursiops truncatus, spotted dolphins, Stenella frontalis, and common dolphins, Delphinus delphis, collected around the Azores and Madeira. Sex ratio was globally skewed in favor of males, and differed between species and archipelagos. Skew was probably influenced by the selectivity of biopsy collectors and seasonal or year-round predominance of males in natural populations. Skew was also influenced by sampling duration and intensity. In the Azores, when several samples were successively collected within the same group, the proportion of female samples decreased as a function of sample order. This trend indicated a tendency for females to increasingly avoid the boat while samples were being collected. It showed that males and females reacted differently to the perturbation caused by the biopsy sampling process (i.e. sample collection and driving style).Portuguese Foundation for Science and Technology (FCT) and the FEDER program for funding the CETAMARH (POCTI/BSE/38991/01) and the GOLFINICHO (POCI/BIA-BDE/61009/2004) projects, S.Q.'s post-doctoral grants (IMAR/FCT- PDOC-006/2001-MoleGen and SFRH/BPD/19680/2004), M.A.S.'s doctoral (SFRH/BD/8609/2002) and post-doctoral (SFRH/BPD/29841/2006) grants, S.M.'s investigation assistant grant (CETAMARHII/POCTI/BSE/38991/2001) and I.C.'s investigation assistant grants (IMAR/FCT/GOLFINICHO/001/2005 and IMAR/FCT/GOLFINICHO/004/2006). FCT for its pluri-annual funding to Research Unit #531 and the EU funded program Interreg IIIb for funding the MACETUS project (MAC/4.2/M10) as well as R.P. and S.M.’s grants (IMAR/INTERREGIIIb/MACETUS/MAC1/2)