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Publications

Publications by Gonçalo Reis Figueira

2015

A decision support system for the operational production planning and scheduling of an integrated pulp and paper mill

Authors
Figueira, G; Amorim, P; Guimaraes, L; Amorim Lopes, M; Neves Moreira, F; Almada Lobo, B;

Publication
COMPUTERS & CHEMICAL ENGINEERING

Abstract
Production planning and scheduling in the process industry in general and in the pulp and paper (P&P) sector in particular can be very challenging. Most practitioners, however, address those activities relying only on spreadsheets, which is time-consuming and sub-optimal. The literature has reported some decision support systems (DSSs) that are far from the state-of-the-art with regard to optimization models and methods, and several research works that do not address industrial issues. We contribute to reduce that gap by developing and describing a DSS that resulted from several iterations with a P&P company and from a thorough review of the literature on process systems engineering. The DSS incorporates relevant industrial features (which motivated the development of a specific model), exhibits important technical details (such as the connection to existing systems and user-friendly interfaces) and shows how optimization can be integrated in real world applications, enhanced by key pre- and post-optimization procedures.

2015

Industrial insights into lot sizing and schedulingmodeling

Authors
Almada Lobo, B; Clark, A; Guimarães, L; Figueira, G; Amorim, P;

Publication
Pesquisa Operacional

Abstract
Lot sizing and scheduling by mixed integer programming has been a hot research topic inthe last 20 years. Researchers have been trying to develop stronger formulations, as well as to incorporatereal-world requirements from different applications. This paper illustrates some of these requirements anddemonstrates how small- and big-bucket models have been adapted and extended. Motivation comes fromdifferent industries, especially from process and fast-moving consumer goods industries. © 2015 Brazilian Operations Research Society.

2015

Modeling lot sizing and scheduling in practice

Authors
Guimarães, L; Figueira, G; Amorim, P; Almada Lobo, B;

Publication
Operations Research and Big Data: IO2015-XVII Congress of Portuguese Association of Operational Research (APDIO)

Abstract
Lot sizing and scheduling by mixed integer programming has been a hot research topic in the last 20 years. Researchers have been trying to develop stronger formulations, as well as to incorporate real-world requirements from different applications. In this paper we illustrate some of these requirements and show howmodels have been adapted and extended. Motivation comes from different industries, especially from process and fast moving consumer goods industries.

2014

Hybrid simulation-optimization methods: A taxonomy and discussion

Authors
Figueira, G; Almada Lobo, B;

Publication
SIMULATION MODELLING PRACTICE AND THEORY

Abstract
The possibilities of combining simulation and optimization are vast and the appropriate design highly depends on the problem characteristics. Therefore, it is very important to have a good overview of the different approaches. The taxonomies and classifications proposed in the literature do not cover the complete range of methods and overlook some important criteria. We provide a taxonomy that aims at giving an overview of the full spectrum of current simulation-optimization approaches. Our study may guide researchers who want to use one of the existing methods, give insights into the cross-fertilization of the ideas applied in those methods and create a standard for a better communication in the scientific community. Future reviews can use the taxonomy here described to classify both general approaches and methods for specific application fields.

2014

Robust Production Planning and Scheduling of a Pulp Digester and a Paper Machine

Authors
Figueira, G; Almada Lobo, B;

Publication
24TH EUROPEAN SYMPOSIUM ON COMPUTER AIDED PROCESS ENGINEERING, PTS A AND B

Abstract
Disturbance Management is a major issue in process industries like the pulp and paper (P&P) case and is mostly performed in the execution/control level. That approach is confined to the amendment of plans sent by upper levels and can thus be problematic. This paper moves towards the integration of planning and control, starting from the planning's point of view. The application of Simulation-Optimization (S-O) allows considering uncertainty, but keeping a deterministic tractable optimization model. Indeed, it is the simulation model that incorporates more complex elements such as stochastic variables, as well as integrates (with more or less detail) the execution/control behaviour. In this work, we present a case study of a P&P mill, focusing on the two most critical production resources (the digester and the paper machine). The feedback obtained by simulating their interaction is used to adjust the slacks introduced in the intermediate tank. In this way, we are able to generate plans that are not only optimized concerning company's indicators, but also robust against disturbances.

2017

Decentralized Vs. Centralized Sequencing in a Complex Job-Shop Scheduling

Authors
Mehrsai, A; Figueira, G; Santos, N; Amorim, P; Almada Lobo, B;

Publication
IFIP Advances in Information and Communication Technology

Abstract
Allocation of jobs to machines and subsequent sequencing each machine is known as job scheduling problem. Classically, both operations are done in a centralized and static/offline structure, considering some assumptions about the jobs and machining environment. Today, with the advent of Industry 4.0, the need to incorporate real-time data in the scheduling decision process is clear and facilitated. Recently, several studies have been conducted on the collection and application of distributed data in real-time of operations, e.g., job scheduling and control. In practice, pure distribution and decentralization is not yet fully realizable because of e.g., transformation complexity and classical resistance to change. This paper studies a combination of decentralized sequencing and central optimum allocation in a lithography job-shop problem. It compares the level of applicability of two decentralized algorithms against the central scheduling. The results show better relative performance of sequencing in stochastic cases. © IFIP International Federation for Information Processing 2017.

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