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- An approach for reliability-based robust design optimisation of angle-ply compositesPublication . António, Carlos Conceição; Hoffbauer, Luísa N.Variations of manufacturing process parameters and environmental aspects may affect the quality and performance of composite materials, which consequently affects their structural behaviour. Reliability-based design optimisation (RBDO) and robust design optimisation (RDO) searches for safe structural systems with minimal variability of response when subjected to uncertainties in material design parameters. An approach that simultaneously considers reliability and robustness is proposed in this paper. Depending on a given reliability index imposed on composite structures, a trade-off is established between the performance targets and robustness. Robustness is expressed in terms of the coefficient of variation of the constrained structural response weighted by its nominal value. The Pareto normed front is built and the nearest point to the origin is estimated as the best solution of the bi-objective optimisation problem.
- An integrated recycling approach for GFRP pultrusion wastes: recycling and reuse assessment into new composite materials using Fuzzy Boolean NetsPublication . Meira Castro, Ana C.; Carvalho, João P.; Ribeiro, M. C. S.; Meixedo, João Paulo; Silva, Francisco J. G.; Fiúza, António; Dinis, M. L.In this study, efforts were made in order to put forward an integrated recycling approach for the thermoset based glass fibre reinforced polymer (GPRP) rejects derived from the pultrusion manufacturing industry. Both the recycling process and the development of a new cost-effective end-use application for the recyclates were considered. For this purpose, i) among the several available recycling techniques for thermoset based composite materials, the most suitable one for the envisaged application was selected (mechanical recycling); and ii) an experimental work was carried out in order to assess the added-value of the obtained recyclates as aggregates and reinforcement replacements into concrete-polymer composite materials. Potential recycling solution was assessed by mechanical behaviour of resultant GFRP waste modified concrete-polymer composites with regard to unmodified materials. In the mix design process of the new GFRP waste based composite material, the recyclate content and size grade, and the effect of the incorporation of an adhesion promoter were considered as material factors and systematically tested between reasonable ranges. The optimization process of the modified formulations was supported by the Fuzzy Boolean Nets methodology, which allowed finding the best balance between material parameters that maximizes both flexural and compressive strengths of final composite. Comparing to related end-use applications of GFRP wastes in cementitious based concrete materials, the proposed solution overcome some of the problems found, namely the possible incompatibilities arisen from alkalis-silica reaction and the decrease in the mechanical properties due to high water-cement ratio required to achieve the desirable workability. Obtained results were very promising towards a global cost-effective waste management solution for GFRP industrial wastes and end-of-life products that will lead to a more sustainable composite materials industry.
- Analyzing the Implementation of Lean Methodologies and Practices in the Portuguese Industry: A SurveyPublication . Pinto, Carla M. A.; Mendonça, Jorge; Babo, Lurdes; Silva, Francisco J. G.; Fernandes, José L. R.The mass production paradigm on which much of the industry was based has changed. The market is increasingly demanding, requesting diversity and products that are more and more adapted to personal wishes and requirements. This implies producing a greater diversity of products in smaller quantities. Competitiveness is enormous, which forces most companies to be truly effective and efficient, taking care of product quality, delivery time, and final cost. Lean methodologies have been a valuable aid in this field. The diversity of Lean tools has been shown to have answers to the most diverse challenges, and companies are aware of this, increasingly adopting methodologies and processes that aim to progressively reduce waste and adapting their production paradigm to what the market requires. This work intends to provide a vision, as global as possible, of the pathway of Lean implementation in the Portuguese industry. For this purpose, a survey was carried out with a significant sample of Portuguese industrial companies from a wide range of activity sectors. The data collected through the survey were treated statistically, and then a SWOT analysis of the results was performed, which provided a collection of precious information on the evolution of industrial companies in Portugal.
- Assessment of direct radiological risk and indirect associated toxic risks originated by Coal-Fired Power PlantsPublication . Dinis, M. L.; Fiúza, António; Góis, Joaquim; Carvalho, José Soeiro de; Meira Castro, Ana C.Over the past few decades there has been some discussion concerning the increase of the natural background radiation originated by coal-fired power plants, due to the uranium and thorium content present in combustion ashes. The radioactive decay products of uranium and thorium, such as radium, radon, polonium, bismuth and lead, are also released in addition to a significant amount of 40K. Since the measurement of radioactive elements released by the gaseous emissions of coal power plants is not compulsory, there is a gap of information concerning this situation. Consequently, the prediction of dispersion and mobility of these elements in the environment, after their release, is based on limited data and the radiological impact from the exposure to these radioactive elements is unknown. This paper describes the methodology that is being developed to assess the radiological impact due to the raise in the natural background radiation level originated by the release and dispersion of the emitted radionuclides. The current investigation is part of a research project that is undergoing in the vicinity of Sines coal-fired power plant (south of Portugal) until 2013. Data from preliminary stages are already available and possible of interpretation.
- Avaliação do impacto do fogo controlado na vulnerabilidade dos solos florestais – uma contribuiçãoPublication . Meira Castro, Ana C.; Meixedo, Joao Paulo; Vivas, AntónioA floresta portuguesa constitui um dos pilares do desenvolvimento económico e social do País e enfrenta dificuldades de gestão face à incerteza associada à sanidade florestal, à economia do futuro e ao clima. A sustentabilidade dos recursos florestais requer, entre outras acções, medidas de preservação dos georecursos e de garantia da diversidade biológica e da fruição estética das florestas. Na floresta, o fogo é um fenómeno ecológico natural. Contudo, a maioria dos incêndios florestais que ocorrem anualmente em Portugal possuem uma natureza antropogénica inequívoca, não só pela origem das ignições mas também pela natureza do coberto vegetal, fortemente determinado pela intervenção humana. As consequências ambientais que se verificam após a ocorrência de um incêndio são indesejáveis reflectem-se em prejuízos nos solos até então protegidos pelo coberto florestal.
- Bi-level dominance GA for minimum weight and maximum feasibility robustness of composite structuresPublication . António, Carlos Conceição; Hoffbauer, Luísa NatáliaIn the proposed approach the robust design optimization (RDO) of composite structures is addressed as a bi-objective optimization problem with following objective functions: (1) the weight of the structure which optimality is associated with performance robustness; and (2) the variability of structural response which is associated with feasibility robustness of design constraints. The determinant of the variance–covariance matrix of the response is adopted for feasibility robustness assessment, being the sensitivities calculated by the adjoint variable method. The design and uncertainty rules are controlled by the following classes of variables and parameters: the deterministic design variables, the random design variables, and the random parameters. To solve the RDO of composite structures an evolutionary algorithm, denoted by Bi-level Dominance Multi-Objective Genetic Algorithm (MOGA-2D) is proposed. The Pareto front is built using a hierarchical structure where evolution is based on the exchange data between two populations: a small population using local dominance and elitism and an enlarged population to store the non-dominated solutions. The numerical tests show the capabilities of the approach. Although the optimal Pareto front establishes the trade-off between performance and robustness, knowledge on the importance of each uncertainty source can help the designer to make a decision on design space.
- A case study on the eco-efficiency performance of a composite processing industry: evaluation and quantification of potential improvementsPublication . Ribeiro, M.C.S.; Meira Castro, Ana C.; Silva, F.J.G.; Meixedo, JP; Oliveira, L.; Alvim, M.R.; Fiúza, A.; Dinis, M.L.In this study, an attempt was made in order to measure and evaluate the eco-efficiency performance of a pultruded composite processing company. For this purpose the recommendations of World Business Council for Sustainable Development (WCSD) and the directives of ISO 14301 standard were followed and applied. The main general indicators of eco-efficiency, as well as the specific indicators, were defined and determined. With basis on indicators’ figures, the value profile, the environmental profile, and the pertinent eco-efficiency ratios were established and analyzed. In order to evaluate potential improvements on company eco-performance, new indicators values and eco-efficiency ratios were estimated taking into account the implementation of new proceedings and procedures, at both upstream and downstream of the production process, namely: i) Adoption of a new heating system for pultrusion die-tool in the manufacturing process, more effective and with minor heat losses; ii) Recycling approach, with partial waste reuse of scrap material derived from manufacturing, cutting and assembly processes of GFRP profiles. These features lead to significant improvements on the sequent assessed eco-efficiency ratios of the present case study, yielding to a more sustainable product and manufacturing process of pultruded GFRP profiles.
- Causas de incêndios florestais em Portugal continental. Análise estatística da investigação efetuada no último quindénio (1996 a 2010)Publication . Lourenço, Luciano; Fernandes, Sofia; Bento-Gonçalves, António; Meira Castro, Ana C.; Nunes, Adélia; Vieira, AntónioAo longo dos últimos anos, Portugal não tem conseguido travar os incêndios florestais, tanto no que diz respeito número de ocorrências como no que se refere à dimensão das áreas ardidas, sobretudo durante o período estival, quando dominam temperaturas elevadas e a dessecação dos combustíveis gera um ambiente propício à propagação dos incêndios, cuja ignição, em mais de 90% dos casos, tem origem em atos humanos, negligentes e intencionais. Com o objetivo de melhor compreender a origem destes incêndios florestais, o presente estudo visa analisar as causas responsáveis pela ignição dos incêndios florestais em Portugal e acompanhar o modo como elas foram evoluindo, quer ao longo do tempo, quer em termos da sua distribuição espacial, no período compreendido entre 1996 e 2010.
- A coinfection model for HIV and HCVPublication . Pinto, Carla M.A.; Carvalho, Ana R.M.We study a mathematical model for the human immunodeficiency virus (HIV) and hepatites C virus (HCV) coinfection. The model predicts four distinct equilibria: the disease free, the HIV endemic, the HCV endemic, and the full endemic equilibria. The local and global stability of the disease free equilibrium was calculated for the full model and the HIV and HCV submodels. We present numerical simulations of the full model where the distinct equilibria can be observed. We show simulations of the qualitative changes of the dynamical behavior of the full model for variation of relevant parameters. From the results of the model, we infer possible measures that could be implemented in order to reduce the number of infected individuals.
- Conceiving modern engineers within the framework of the sustainability action plan (PASUS) of ISEP: sustainability matters!Publication . Caetano, Nídia Sá; Meira Castro, Ana C.; Castanheira, Luís; Cardoso, Marilio; Silva, António; Rocha, JoãoEngineering education practices have evolved not only due to the natural changes in the contents of the curricula and skills but also, and more recently, due to the requirements imposed by the Bologna revision process. In addition, industry is becoming more demanding, as society is becoming more and more aware of the global needs and consequences of industrial practices. Under this scope, higher education needs not only to follow but also to lead these trends. Therefore, the School of Engineering of the Polytechnic Institute of Porto (ISEP), a Global Reporting Initiative (GRI) training partner in Portugal, prepared and presented its Sustainability Action Plan (PASUS), with the main objective of creating a new kind of engineers, with Sustainable Development at the core of their graduation and MsC degrees. In this paper, the main strategies and activities of the referred plan along with the strategic approach, which guided its development and implementation, will be presented in detail. Additionally, a reflection about the above mentioned bridge between concept and application will be established and justified, in the framework of the action plan. Although in most of the situations, there was no prior discussion or specific request, many of the graduation and post-graduation programmes offered by ISEP already include courses that attend to PASUS philosophy. As a consequence, the number of Master thesis, Graduation projects and R&D projects that address sustainability problems has grown substantially, a proof that for ISEP community, sustainability really matters!