2013
Authors
Rocha, M; Oliveira, JF; Carravilla, MA;
Publication
JOURNAL OF SCHEDULING
Abstract
In this work, we propose a general integer programming model to address the staff scheduling problem, flexible enough to be easily adapted to a wide-range of real-world problems. The model is applied with slight changes to two case studies: a glass plant and a continuous care unit, and also to a collection of benchmark instances available in the literature. The emphasis of our approach is on a novel formulation of sequence constraints and also on workload balance, which is tackled through cyclic scheduling. Models are solved using the CPLEX solver. Computational results indicate that optimal solutions can be achieved within a reasonable amount of time.
2013
Authors
Bennell, JA; Oliveira, JF; Waescher, G;
Publication
INTERNATIONAL JOURNAL OF PRODUCTION ECONOMICS
Abstract
2015
Authors
Ribeiro, JP; Rossetti, RJF; Oliveira, JF;
Publication
13th International Industrial Simulation Conference 2015, ISC 2015
Abstract
Cutting and packing problems generally address the cutting or packing of smaller items into a larger container object. Usually, the main methodologies used in the Circular Open Dimension Problem (CODP) are nonlinear programming methods or methods that combine different heuristics. The aim of this project is at devising and using an agent-based simulation approach to determine the length of the open rectangle in CODP; more specifically, we look into the Circular two-dimension Open Dimension Problem. Agents (circles, which can have different dimensions) were given a set of simple rules that allow them to be placed in the world (i.e. an open rectangle). These rules are inferred from the formal CODP formulation and from the behavior defined in the agents.
2018
Authors
Mundim, LR; Andretta, M; Carravilla, MA; Oliveira, JF;
Publication
INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH
Abstract
Cutting raw-material into smaller parts is a fundamental phase of many production processes. These operations originate raw-material waste that can be minimised. These problems have a strong economic and ecological impact and their proper solving is essential to many sectors of the economy, such as the textile, footwear, automotive and shipbuilding industries, to mention only a few. Two-dimensional (2D) nesting problems, in particular, deal with the cutting of irregularly shaped pieces from a set of larger containers, so that either the waste is minimised or the value of the pieces actually cut from the containers is maximised. Despite the real-world practical relevance of these problems, very few approaches have been proposed capable of dealing with concrete characteristics that arise in practice. In this paper, we propose a new general heuristic (H4NP) for all 2D nesting problems with limited-size containers: the Placement problem, the Knapsack problem, the Cutting Stock problem, and the Bin Packing problem. Extensive computational experiments were run on a total of 1100 instances. H4NP obtained equal or better solutions for 73% of the instances for which there were previous results against which to compare, and new benchmarks are proposed.
2018
Authors
Paquay, C; Limbourg, S; Schyns, M; Oliveira, JF;
Publication
INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH
Abstract
This article is about seeking a good feasible solution in a reasonable amount of computation time to the three-dimensional Multiple Bin Size Bin Packing Problem (MBSBPP). The MBSBPP studied considers additional constraints encountered in real world air transportation situations, such as cargo stability and the particular shape of containers. This MBSBPP has already been formulated as a Mixed Integer linear Programming problem, but as yet only poor results have been achieved for even fairly small problem sizes. The goal of the work this paper describes is to develop heuristics that are able to quickly provide good initial feasible solutions for the MBSBPP. Three methodologies are considered, which are based on the decomposition of the original problem into easier subproblems: the matheuristics Relax-and-Fix, Insert-and-Fix and Fractional Relax-and-Fix. They have been parametrised on real data sets and then compared to each other. In particular, two of these techniques show promising results in reasonable computational times.
2018
Authors
Carravilla, MA; Oliveira, JF;
Publication
Lecture Notes in Logistics
Abstract
In this chapter, we outline the issue of education in the field of Operations Research (OR) and discuss various educational resources that are currently available, with a main focus on the most important international resources, but also with an emphasis on what is currently done in our home country, Portugal. The identification of shortcomings of education in OR and opportunities for its development will follow from the analysis of these resources. By choosing the word “education” over “teaching”, the aim is to stress the fact that (formal) teaching is nothing but one of the multiple aspects of education, whatever the field may be. Finally, we conclude that the dissemination and promotion of the field of OR intimately relates to issues related to education in this field. It is shown that these activities create a direct impact on the ability to attract publics into educational activities in this area, such as students enrolment on courses and programs with a high OR content. © 2018, Springer International Publishing AG.
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