ISEP – CIDEM – Comunicações em eventos científicos
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- Advanced Calculation Model Calibrated with Experimental Test of Wooden Slabs Exposed to FirePublication . Fonseca, Elza M M; Piloto, Paulo A GThe wooden slabs are structural elements with wide application, in particular, in building rehabilitation, interior spaces and in new building structures. The mechanical, thermal and acoustic properties make this material as an ideal solution for floor and roof slabs applications. However, when exposed to an accidental fire condition it is necessary to assess their vulnerable behaviour accurately. In this work, an advanced calculation model is presented, based on the use of finite elements, calibrated with experimental results. The experimental tests were performed on wooden slabs exposed to a fire from below the element. The slabs were instrumented with thermocouples to measure the temperature at different control points along the fire duration in a fire resistance furnace, following the standard fire curve ISO 834. The advanced calculation model also allows the obtained the transient effect and incorporates the non-linear wood properties. The physical behaviour of the wooden slab is conditioned by the char layer formation, and this phenomenon is also considered in the advanced calculation model.
- Advances in thermoplastic pultruded compositesPublication . Novo, P. J.; Silva, João F.; Nunes, J. P.; Marques, A. T.Pultrusion is a versatile continuous high speed production technology allowing the production of fibre reinforced complex profiles. Thermosetting resins are normally used as matrices in the production of structural constant cross section profiles. Although only recently thermoplastic matrices have been used in long and continuous fibre reinforced composites replacing with success thermosetting matrices, the number of their applications is increasing due to their better ecological and mechanical performance. Composites with thermoplastic matrices offers increased fracture toughness, higher impact tolerance, short processing cycle time and excellent environmental stability. They are recyclable, post-formable and can be joined by welding. The use of long/continuous fibre reinforced thermoplastic matrix composites involves, however, great technological and scientific challenges since thermoplastics present much higher viscosity than thermosettings, which makes much difficult and complex the impregnation of reinforcements and consolidation tasks. [1] In this work continuous fibres reinforced thermoplastic matrix towpregs were produced using equipment developed by the Institute for Polymers and Composites (IPC). The processing of the towpregs was made by pultrusion, in a developed prototype equipment existing in the Engineering School of the Polytechnic Institute of Porto (ISEP). Different thermoplastic matrices and fibres raw-materials were used in this study to manufacture pultruded composites for commercial applications (glass and carbon fibre/ polypropylene) and for advanced markets (carbon fibre/Primospire®). To improve the temperature distribution profile in heating die, different modifications were performed. In order to optimize both processes, towpregs production and pultruded composites profiles were analysed to determine the influence of the most relevant processing parameters in the final properties. The final pultruded composite profiles were submitted to mechanical tests to obtain the relevant properties.
- Analysis and improvement of internal logistic flows at an industrial companyPublication . Baptista, S.; Pereira, Maria Teresa; Ferreira, Luís PintoUndertaken at Preh Portugal, Ltd., the main objective of this study project resided in defining the system of supply to a new assembly line, the Ford B479. Supply to the assembly lines is a crucial activity in internal logistics since the entire production system relies on the supply of materials required for the line. It is, therefore, extremely important to study solutions which will facilitate these activities, thus enhancing productivity and guaranteeing the on-time availability of products, in suitable quantities and at the best cost. The initial phase consisted of studying the type of supply system used by the company for the remaining lines, as well as gaining a detailed understanding of the entire assembly line production process. One was then able to create a database to include all of this information. Once all the required information had been gathered, one proceeded to define the supermarket for the Ford B479 line, and calculated the number of positions required. With the purpose of building a more effective and efficient supermarket, one analyzed the possibility of building the supermarket next to line instead of resorting to the existing solution where the shelves for all lines are in the same location. When the site for the supermarket was defined, one proceeded with its construction and determined the supply system of both the supermarket as well as the line sides. Due to the proposed changes, one was able to reduce the distance covered by raw materials by 55% as well as to decrease handling.
- Analysis and Improvement of the Packaging Sector of an Industrial CompanyPublication . Alves, Diogo; Ferreira, Luís Pinto; Pereira, Maria Teresa; Sá, José Carlos; Silva, Francisco J. G.; Fernandes, N.O.Manual operations in manufacturing companies are still a common practice. This often results in high costs, high cycle times and therefore in lower productivity, particularly for companies operating in western countries. This is why many manufacturing companies relocated their production facilities in low age countries. This study was developed at a leading Portuguese material construction manufacturing company. The objective was to improve the packaging and labeling processes, that were identified as main bottlenecks in the factory. Lean was used to streamline these processes before being automated. This allowed for annual savings of 12432 €, with human operators being reallocated to other departments where they are more useful. Furthermore, cycle times were reduced by 42,9%, non-value-added activities were minimized, and operations with potentially high ergonomic risks were eliminated. In addition, a reduction of 84,3% in lithographed packaging was achieved, with a cost reduction of around 36 000 €/year, which is expected to continue in the forthcoming years.
- Analysis and quantification of damage in polymer composite materialsPublication . Durão, Luís Miguel; Matos, João E.; Silva, PedroThe specific characteristics of composite materials, like carbon fibre reinforced plastics, have been leading to their rising importance and widespread use. As these parts are normally produced in a nearnet shape, secondary operations, like drilling, are necessary prior to their assembly in complex structures. It is still difficult to define a machining process that enables free damage holes, due to the peculiar laminar nature of these materials. So, the definition of a drilling process that minimizes delamination and increases reliability in produced parts combined with satisfactory cost and productivity is still of major importance in the composites manufacturing industry. In this paper two sets of unidirectional coupons from plates with carbon fibre as reinforcement and epoxy resin as matrix, are drilled using five different drilling tool strategies and two feed rates for uneven damage extension. One of the strategies is the use of a pre-drilling option. Then the delamination is assessed using enhanced radiography and, finally, two diverse mechanical tests are performed on the resulting coupons: three point bending and pin bearing. The results allowed establishing and modelling, with the help of statistical tools, the relations between the damaged area caused by drilling and the material’s mechanical resistance. The bending resistance does not vary greatly with the damage area. On the other hand, the bearing resistance decreases with the increase of the damaged area.
- Analysis of a Customer Relationship Management Tool in a Shipping CompanyPublication . Pereira, Maria Teresa; Fróis, Joana; Ferreira, Fernanda A.Today’s society is technologically advanced, the world is just a click away and our companies’ customers have easy access to all the information. Therefore, they are increasingly demanding, wanting more and better at a lower cost. Using as a case study a shipping company, a system of Customer Relationship Management (CRM) was analysed to verify what reasons led to its abandonment and to realise what to do to reverse such situation. In this industry product differentiation is practically null, so the customer’s choice comes down to price. However, customers are paying more attention to customer service, therefore companies are developing stronger relationships with them. The construction of such relationships implies data collection on the client, from which one can offer services of greater value. This may lead to partnerships and competitive advantages. Thus, the use of CRM tools is being promoted for CRM tools present themselves as a valuable asset. In the end, suggestions are presented, ranging from improvements to the existing system, to more complex suggestions, costlier or breaking with the existing mode of relationship and dialogue between company and customers, but that, in the future, will certainly translate into advantages over competing companies.
- Aplicação da definição nZEB da REHVA a uma renovação de um edifício de habitação Português.Publication . Monteiro, Joaquim; Castro, OlgaOs edifícios desempenham um papel-chave nas sociedades que estão a tentar atenuar os efeitos das alterações climáticas. Mais de 50% dos edifícios residenciais existentes na UE-25 foram construídos antes de 1970. Assim, estes edifícios são de significativa importância na redução de consumo de energia e emissões de CO2. Os edifícios de balanço de energia (quase) zero (nZEB) são uma solução possível para este problema. Este estudo tem por objetivo analisar a aplicação da metodologia nZEB no retrofitting de uma habitação típica Portuguesa de 1950. Foi demonstrado que a energia primária utilizada pode ser reduzida a um valor muito baixo (11,95 kWh/m2.ano) em comparação com o consumo de referência (69,15 kWh/m2.ano), através da aplicação das melhores técnicas atuais de construção, juntamente com a utilização de energia produzida localmente através de fontes renováveis. O uso de fontes de energia renovável permitiu que este edifício alcançasse um valor de RERp de 89%.
- Avaliação distribuída, sucesso académico e desempenho autónomo: o caso dos estudantes de Termodinâmica da licenciatura em Engenharia Mecânica do ISEPPublication . Duarte, MarinaSegundo o Assessment Reform Group, a avaliação é uma das ferramentas educativas mais poderosas na promoção de uma aprendizagem efetiva, quando utilizada de forma correcta. Não há evidências que aumentar a quantidade de avaliação melhore a aprendizagem. Não obstante, existem sempre circunstâncias nas quais mais ensino é mais eficaz do que mais avaliação ou feedback. A redução do tempo de ensino (horas de contacto) trazida pelo processo de Bolonha e, mais recentemente, pelas restrições orçamentais impostas às instituições de ensino superior, deve ser ponderada cuidadosamente, pois existe o perigo de, numa altura em que se pretende que os alunos sejam agentes da sua própria aprendizagem, construído-a, que o ensino se esteja a tornar insuficiente e incapaz de desempenhar o seu papel estruturante, de base sobre a qual assenta a aprendizagem. Apesar da prática sistemática de avaliação formativa melhorar substancialmente as aprendizagens, não deixa de ser um recurso de última instância, pois pode comprometer o desempenho autónomo e independente, a longo prazo. Assim sendo, e considerando também os recursos envolvidos na implementação deste tipo de avaliação, é necessária bastante ponderação e uma análise de quais os estudantes que dela poderão beneficiar e se essa é a forma mais adequada de o fazer. Este estudo abrangeu 238 estudantes de 2008/09 da unidade curricular de Termodinâmica do 2º ano da licenciatura em Engenharia Mecânica do Instituto Superior de Engenharia do Porto, numa situação em que tinham a opção de realizar ou não avaliação distríbuida, para além da avaliação por exame final (que teria peso 70% ou 100%, consoante a opção escolhida). Independentemente da escolha, a classificação mínima exigida na avaliação por exame final era 9,5 valores. A obtenção de uma classificação inferior a 7,5 valores na avaliação distribuída impedia a comparência ao exame final (implicando reprovação imediata). Com este estudo, procurou atingir-se os seguintes objetivos: 1) Verificar se os estudantes optaram por mecanismos de regulação externos, como a avaliação distribuída, nas condições descritas; 2) Caracterizar o sucesso académico dos estudantes que optaram pela avaliação distribuída, de acordo com o número de inscrições na unidade curricular. A estratégia adoptada para implementação do plano de investigação foi descritiva, recorrendo à análise das pautas de Termodinâmica. Os dados recolhidos parecem indicar que os estudantes reconhecem a necessidade de mecanismos de regulação externa e que estes favorecem o desempenho académico na unidade curricular de Termodinâmica, particularmente dos estudantes que a frequentam pela primeira vez. Ou seja, apesar de serem estudantes do 2º e 3º ano da licenciatura parecem não ter ainda desenvolvido mecanismos de auto-regulação eficazes para a aprendizagem de Termodinâmica, ficando dependentes das atividades propostas pelo docente através da avaliação distribuída. A auto-regulação parece melhorar com a frequência em anos posteriores, revelando o que parece ser um desajuste entre o “tempo de ensino” e o “tempo de aprendizagem”, nomeadamente no que concerne à capacidade para o desenvolvimento do desempenho autónomo e independente.
- Blended learning and learner autonomy in higher education: a study with mechanical engineering studentsPublication . Duarte, MarinaAs higher education faces the challenge of new and diverse demand, with more and non-traditional students enrolling in courses, it seems difficult to find a way to keep the standards as the funds decrease and the budget isn’t enough to hire new faculty. A solution to this challenge is to use blended learning, combining online and in-class content and participation. This technology based model allows students to access resources at any time, according to their needs and constraints, such as work schedules. The faculty can monitor student access and work, and offer additional explanation when needed. On the other hand, as face-to-face classes decrease, and fewer contact hours are involved, it’s necessary to move fundamental knowledge acquisition out of the classroom and devote classroom time to applying, integrating and synthesizing the knowledge, allowing faculty to work with smaller groups. This means that a greater part of the teaching-learning transaction occurs away from schools and faculty, and that students have more control of their own learning, shifting from academic teaching staff to the learner, which fosters student-centred learning. Also, taking charge of one’s learning is a fundamental skill to lifelong learning, which has been recognized as an essential element of the European Higher Education Area. But, are all students ready to take charge of their own learning? Are all students able to take charge of their own learning? Learner autonomy is the ability to take charge of one's own learning, as long as the learning environment provides opportunities for the learner to take control of their learning. In this study the relationship between students’ perception of their own learner autonomy and the willingness to learn in a blended learning environment will be investigated.
- Carga horária vs carga de trabalho: mudanças introduzidas pelo Processo de BolonhaPublication . Duarte, MarinaCom a implementação do Processo de Bolonha, a estrutura de graus em Portugal passou a ser constituída por três ciclos, com a duração total de oito anos. Estes três novos (ou reformulados) ciclos passaram a ser organizados em função de créditos, tendo cada semestre 30 créditos. O crédito é uma medida da carga de trabalho do estudante baseada no tempo necessário para completar uma dada unidade curricular, e inclui as horas de aulas (carga horária), de avaliação e também de estudo independente. Para uma correta atribuição dos créditos, é necessário saber quanto tempo efetivamente os estudantes estão a dedicar a cada unidade curricular. Neste estudo procura-se averiguar qual é a carga de trabalho reportada pelos estudantes, e como esta se distribui entre a componente de horas de contacto (carga horária) e de horas de trabalho autónomo e em função do horário de frequência do curso (diurno ou pós-laboral) e do ano curricular (1º, 2º e 3º ano). Os participantes são estudantes do 1º ciclo de um curso de engenharia. Os resultados mostram que os estudantes têm uma carga de trabalho inferior à prevista pelos créditos, com 60% a corresponder a atividades realizadas na presença do professor e 40% para estudo e realização de trabalhos fora de aulas. Face a estes resultados, sugere-se uma análise dos dados da carga de trabalho relativamente a indicadores de desempenho académico, de modo a verificar se estas baixas cargas de trabalho afetam o desempenho dos estudantes.