Scheduling aircraft’s engines repair process: a mathematical model

In this talk, we discuss a scheduling problem that originated at TAP - Maintenance & Engineering - the maintenance, repair and overhaul organization of Portugal’s leading airline. In the repair process of aircrafts’ engines, the operations to be scheduled may be executed on a certain workstation by any processor of a given set, and the objective is to minimize the total weighted tardiness. A mixed integer linear programming formulation, based on the flexible job shop scheduling, is presented here, along with computational experiment on a real instance, provided by TAP-ME, from a regular working week. The model was also tested using benchmarking instances available in literature.

A simplified four-branch model for the analytical study of the out-of-plane performance of regular stone URM walls

During the last years, several studies have been made aiming to assess the out-of-plane seismic response of unreinforced stone masonry structures. This fact led to the development of a wide variety of models and approaches, ranging from simple kinematic based analytical models up to complex numerical simulations. Nevertheless, for the sake of simplicity, the out-of-plane seismic response of a masonry wall pier may be obtained by means of a simple single-degree-of-freedom system while still providing good results. In fact, despite the assumptions associated with such a simple formulation, it is also true that the epistemic uncertainty inherent with the selection of appropriate input parameters in more complex models may render them truly ineffective. In this framework, this paper focuses on the study of the out-of-plane bending of unreinforced stone masonry walls (cantilevers) by proposing a simplified analytical approach based on the construction of a linearized four-branch model, which is used to characterize the linear and nonlinear response of such structural elements through an overturning moment-rotation relationship. The formulation of the four-branch model is presented and described in detail and the meaningful parameters used for its construction are obtained from a set of experimental laboratory tests performed on six full-scale unreinforced regular sacco stone masonry specimens. Moreover, a parametric analysis aiming to evaluate the effect of these parameters’ variation on the final configuration of the model is presented and critically discussed. Finally, the results obtained from the application of the developed four-branch model on real unreinforced regular sacco stone masonry walls are thoroughly analysed and the main conclusions obtained from its application are summarized.

Experimental characterization of the out-of-plane performance of regular stone masonry walls, including test setups and axial load influence

Stone masonry is one of the oldest and most worldwide used building techniques. Nevertheless, the structural response of masonry structures is complex and the effective knowledge about their mechanical behaviour is still limited. This fact is particularly notorious when dealing with the description of their out-of-plane behaviour under horizontal loadings, as is the case of the earthquake action. In this context, this paper describes an experimental program, conducted in laboratory environment, aiming at characterizing the out-of-plane behaviour of traditional unreinforced stone masonry walls. In the scope of this campaign, six full-scale sacco stone masonry specimens were fully characterised regarding their most important mechanic, geometric and dynamic features and were tested resorting to two different loading techniques under three distinct vertical pre-compression states; three of the specimens were subjected to an out-of-plane surface load by means of a system of airbags and the remaining were subjected to an out-of-plane horizontal line-load at the top. From the experiments it was possible to observe that both test setups were able to globally mobilize the out-of-plane response of the walls, which presented substantial displacement capacity, with ratios of ultimate displacement to the wall thickness ranging between 26 and 45 %, as well as good energy dissipation capacity. Finally, very interesting results were also obtained from a simple analytical model used herein to compute a set of experimental-based ratios, namely between the maximum stability displacement and the wall thickness for which a mean value of about 60 % was found.

Que alternativa ao currículo regular no ensino básico?

Encaramos o currículo como um projeto em constante transformação, que tendo por referência o currículo nacional, é adequado ao seu públicoalvo, os alunos. No contexto de cada comunidade onde a escola está inserida, a definição das ofertas educativas/curriculares assume maior pertinência, podendo contemplar componentes locais e regionais do currículo, valorizando as caraterísticas de cada região e, sobretudo, engrandecer os talentos dos alunos, de acordo com as suas especificidades individuais. A reflexão, realizada em torno das dificuldades que muitos alunos têm em realizar as aprendizagens previstas no currículo oficial, deu origem a uma questão central: Que alternativa ao currículo regular no ensino básico? Na procura de respostas à questão, abordamos o nascimento da escola e conceitualização de currículo, a evolução da formação para o mundo do trabalho, a diversificação curricular e a autonomia da escola. O estudo empírico seguiu uma metodologia quantitativa e qualitativa, através de um estudo de caso e centrou-se: na análise documental do Projeto Educativo do Agrupamento; inquérito por questionário aos alunos do terceiro ciclo do ensino básico, regular e cursos vocacionais; inquérito por entrevistas semiestruturadas ao Presidente do Conselho Geral do Agrupamento, Diretora do Agrupamento, Coordenadoras de Departamento, Coordenador dos Cursos Vocacionais e representante no Conselho Pedagógico dos Serviços de Psicologia e Orientação. Expomos as conclusões da investigação através da triangulação dos dados obtidos com os instrumentos de recolha. Como resposta à questão inicial, apresentamos uma proposta alternativa ao currículo regular do ensino básico, que procura diversificar a oferta.