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Publications

2018

A Study in Pairwise Clustering for Bi-dimensional Irregular Strip Packing Using the Dotted Board Model

Authors
Sato, AK; Setter Bauab, GES; Martins, TD; Guerra Tsuzuki, MDG; Gomes, AM;

Publication
IFAC-PapersOnLine

Abstract
The bi-dimensional irregular strip packing is a difficult problem in the cutting and packing field. Its main feature, and central source of complexity, is the irregularity of the shape of the items. Consequently, mathematical solvers are only able to obtain optimal solutions for small instances and heuristics are often employed in the literature. In such algorithms, it is not possible to guarantee that the optimum solution is found. In such cases, a restricted version of the problem can be adopted in order to improve the performance. One possible restriction is the adoption of pairwise clustering, i.e., elimination of items by joining two pieces. In this work, an automatic pairwise clustering method is proposed for the dotted board model, which limits the placement of items to equally distributed discrete points. The clustered problems are then used as input to an irregular strip packing solver. The results obtained in this paper can be used as an initial guideline for the use of clustering in a discrete grid, which was beneficial in some of the tested cases. © 2018

2017

Cargo dynamic stability in the container loading problem -a physics simulation tool approach

Authors
Ramos, AG; Jacob, J; Justo, JF; Oliveira, JF; Rodrigues, R; Gomes, AM;

Publication
International Journal of Simulation and Process Modelling

Abstract
The container loading problem (CLP) is a real-world driven, combinatorial optimisation problem that addresses the maximisation of space usage in cargo transport units. The research conducted on this problem failed to fulfill the real needs of the transportation industry, owing to the inadequate representation of practical-relevant constraints. The dynamic stability of cargo is one of the most important practical constraints. It has been addressed in the literature in an over-simplified way which does not translate to real-world stability. This paper proposes a physics simulation tool based on a physics engine, which can be used to translate real-world stability into the CLP. To validate the tool, a set of benchmark tests is proposed and the results obtained with the physics simulation tool are compared to the state-of-the-art simulation engineering software Abaqus Unified FEA. Analytical calculations have been also conducted, and it was also possible to conclude that the tool proposed is a valid alternative. Copyright © 2017 Inderscience Enterprises Ltd.

2016

Constraint aggregation in non-linear programming models for nesting problems

Authors
Rocha, P; Gomes, AM; Rodrigues, R; Toledo, FMB; Andretta, M;

Publication
Lecture Notes in Economics and Mathematical Systems

Abstract

2016

Preface to the Special Issue on Cutting and Packing

Authors
Gomes, AM; Goncalves, JF; Alvarez Valdes, R; de Carvalho, JV;

Publication
International Transactions in Operational Research

Abstract

2016

Study of the grid size impact on a raster based strip packing problem solution

Authors
Sato, AK; Guerra Tsuzuki, MDG; de Castro Martins, TD; Gomes, AM;

Publication
IFAC PAPERSONLINE

Abstract
Cutting and packing (C&P) is an important area of operational research and its problems arise in various industries such as: textile, wood, glass and shipbuilding. The main objective is to maximize the efficiency of a layout by rearranging and/or reassigning items inside containers in order to reduce costs and environmental impact. In this work, a raster solution to the bidimensional irregular strip packing problem, which consists of placing irregular shapes items inside a single rectangular container with variable length, is studied. In raster methods, the selection of the grid size is very important to the outcome of the algorithm. It influences the size of the search space, the overlap algorithm efficiency, as well as the memory requirements of the packing algorithm. An analysis of the impact of the choice of grid size is performed using 15 benchmark cases from the literature and, through careful observation of such test results, a simple rule to define the grid size is suggested.

Supervised
thesis

2017

Definição e Mapeamento do Processo de Industrialização na Produção de Autocarros

Author
Tiago Gil da Rocha Marques e Barbieri de Figueiredo

Institution
UP-FEUP

2017

Reorganização do processo de paletização numa indústria do ramo alimentar

Author
Marcelo Conde Pinto Arcanjo

Institution
UP-FEUP

2016

Organização dos Fluxos de Informação e Materiais na Produção

Author
Ana Filipa Pinto Tavares

Institution
UP-FEUP

2016

Melhorias no fabrico e balanceamento de um produto em arranque de produção

Author
Rúben Filipe Morais Morgado Osório Ferreira

Institution
UP-FEUP

2015

Desenvolvimento de Estratégia de Manutenção Preditiva e Otimização do Armazém de Peças

Author
José Diogo Cabral Castelo Branco Ribeiro

Institution
UP-FEUP