Percorrer por autor "Costa, L."
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- Analysis of the domain of applicability of an algorithm for a resources system selection problem for Distributed/Agile/Virtual Enterprises integrationPublication . Ávila, Paulo; Costa, L.; Bastos, João; Lopes, P.The process of resources systems selection takes an important part in Distributed/Agile/Virtual Enterprises (D/A/V Es) integration. However, the resources systems selection is still a difficult matter to solve in a D/A/VE, as it is pointed out in this paper. Globally, we can say that the selection problem has been equated from different aspects, originating different kinds of models/algorithms to solve it. In order to assist the development of a web prototype tool (broker tool), intelligent and flexible, that integrates all the selection model activities and tools, and with the capacity to adequate to each D/A/V E project or instance (this is the major goal of our final project), we intend in this paper to show: a formulation of a kind of resources selection problem and the limitations of the algorithms proposed to solve it. We formulate a particular case of the problem as an integer programming, which is solved using simplex and branch and bound algorithms, and identify their performance limitations (in terms of processing time) based on simulation results. These limitations depend on the number of processing tasks and on the number of pre-selected resources per processing tasks, defining the domain of applicability of the algorithms for the problem studied. The limitations detected open the necessity of the application of other kind of algorithms (approximate solution algorithms) outside the domain of applicability founded for the algorithms simulated. However, for a broker tool it is very important the knowledge of algorithms limitations, in order to, based on problem features, develop and select the most suitable algorithm that guarantees a good performance.
- Powered smart textile-based exoskeleton for human support movementPublication . Ferreira, C.; Fertuzinhos, A.; Silva, R.; Ramalho, M.; Vale, B.; Silva, J.; Costa, L.; Oliveira, C.; Ramôa, A.; Aguiar, F.; Pilastri, A.; Matta, A.; Dias, P.; Sampaio, R.; Machado, D.; Costa, M.; Roças, A.; Madureira, P.; Moreira, Juliana; Pereira, J. R.; Pereira, C.; Pereira, F. B.Industrial environments require people’s physical efforts related to excessive force, poor posture, and repetitive tasks that increase the risk of developing musculoskeletal diseases. Due to the high prevalence of postural complaints and consequent global health burdens, a significant demand has been conducted to build and implement powered lower and upper limb devices for human enhancement, considering the working layout/position, anthropometric and ergonomic data to generate valuable information for posture correction guidance.
- Techno-economic assessment of a Synechocystis based biorefinery through process optimizationPublication . Ferreira da Silva, A.; Brazinha, C.; Costa, L.; Caetano, NídiaSimilar to oil, biological origin feedstock can be converted into a number of products allowing to recover the maximum value from the raw biological material, within what is nowadays called a biorefinery. Among other biological materials, microalgae are a very interesting biomass due to the high economic value of certain cellular components, such as carotenoids and polyunsaturated fatty acids. In this project, a genetically modified cyanobacteria, that produces ethanol as an extracellular product, was used as the basis of this study. In order to assess the optimal configuration of the biorefinery, different scenarios were designed, each one with different sequences of unit operations, equipment and products. With the design stage completed, an economic analysis was performed to choose the 2 scenarios with the best economic performance.