Peito, Francisco; Pereira, Guilherme; Leitão, Armando; Dias, Luís M.S.
This paper is concerned with the use of simulation as a decision support tool in maintenance systems, specifically in MFS (Maintenance Float Systems). For this purpose and due to its high complexity, in this paper the authors propose a flexible way to develop typical MFS models, for any number of machines in the workstation, spare machines and maintenance crews. Arena® simulation language is used to understand a specific MFS, create the corresponding MFS model and analyze most common performance measures.
Vaz, Clara B.; Camanho, Ana
This study develops a framework that combines different methods
to provide insights regarding the performance of retailing stores.
Firstly, the framework enables to specify appropriate targets for
stores using DEA. This involves comparing stores within homogeneous
groups. Secondly, the framework compares the overall
performance of these groups. This requires the combined use of
Malmquist type index and statistical tests. This index is decomposed
into components for comparing the efficiency spread between
groups and the productivity differences between the best-practice
frontiers of the groups.
Geraldes, Carla A.S.; Carvalho, Sameiro; Pereira, Guilherme
An important warehouse operation decision concerns the definition of a storage location policy, including the definition of functional areas and the identification of each stock item location in the warehouse. Empirical approaches are often used. However, they do not guarantee that the lowest cost materials-handling solution is achieved. This paper presents a clustering approach to address the assignment of stock items to particular warehouse functional areas. A linear programming model is adapted to a case study and its performance is assessed through the use of real data. Model is solved using LINGO 9.0 mixed integer commercial solver. The output of...
Duarte, António J.S.T.; Carvalho, J.M. Valério de
This work presents an algorithm for solving exactly a scheduling problem with identical
parallel machines and malleable tasks, subject to arbitrary release dates and due dates. The objective is to
minimize a function of late work and setup costs. A task is malleable if we can freely change the set of
machines assigned to its processing over the time horizon. We present an integer programming model, a
Dantzig-Wolfe decomposition reformulation and its solution by column generation. We also developed
an equivalent network flow model, used for the branching phase. Finally, we carried out extensive
computational tests to verify the algorithm’s efficiency and to determine the model’s...
Vaz, Clara B.; Camanho, Ana; Guimarães, Rui
APDIO - Associação Portuguesa de Investigação Operacional e EURO