Browsing by Author "Lopes, Manuel P."
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- Dynamic stability metrics for the container loading problemPublication . Ramos, A. Galrão; Oliveira, José F.; Gonçalves, José F.; Lopes, Manuel P.The Container Loading Problem (CLP) literature has traditionally evaluated the dynamic stability of cargo by applying two metrics to box arrangements: the mean number of boxes supporting the items excluding those placed directly on the floor (M1) and the percentage of boxes with insufficient lateral support (M2). However, these metrics, that aim to be proxies for cargo stability during transportation, fail to translate real-world cargo conditions of dynamic stability. In this paper two new performance indicators are proposed to evaluate the dynamic stability of cargo arrangements: the number of fallen boxes (NFB) and the number of boxes within the Damage Boundary Curve fragility test (NB_DBC). Using 1500 solutions for well-known problem instances found in the literature, these new performance indicators are evaluated using a physics simulation tool (StableCargo), replacing the real-world transportation by a truck with a simulation of the dynamic behaviour of container loading arrangements. Two new dynamic stability metrics that can be integrated within any container loading algorithm are also proposed. The metrics are analytical models of the proposed stability performance indicators, computed by multiple linear regression. Pearson’s r correlation coefficient was used as an evaluation parameter for the performance of the models. The extensive computational results show that the proposed metrics are better proxies for dynamic stability in the CLP than the previous widely used metrics.
- iLeanDMAIC – A methodology for implementing the lean toolsPublication . Ferreira, C.; Sá, José Carlos; Ferreira, Luís Pinto; Lopes, Manuel P.; Pereira, Maria Teresa; Silva, F.J.G.Organizations focus must reside in their constant desire for improvement in order to satisfy their clients as a result of high-quality products, thus maximizing their profits through a waste reduction in the flow production. Lean thinking allows organizations to identify and eliminate wastes within the organization. The use of lean tools is considered a simple, efficient and cost-effective solution to achieve productivity and profit. DMAIC (Define, Measure, Analyze, Improve, Control) is a problem-solving methodology that improves processes, allows defect reduction and reduction of process variability, allowing companies to continuously improve their efficiency and performance. In this work, a combined methodology iLeanDMAIC based on Lean Tools and DMAIC was developed, aiming to help organizations to easily and accurately solve their problems. It includes a case-study implementation on an organization of the sector of wood products. We were able to successfully validate this methodology and to show its efficacy in enhancing production. Results using iLeanDMAIC allowed a reduction time in changeover in the assembly machine (from 39 min to 17 min), presenting this a 44% gain on manufacture. iLeanDMAIC can help organizations thrive against their competitors, make their business more cost-effective and efficient.