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013
Publications

2021

Improving picking performance at a large retailer warehouse by combining probabilistic simulation, optimization, and discrete-event simulation

Authors
Amorim Lopes, M; Guimaraes, L; Alves, J; Almada Lobo, B;

Publication
INTERNATIONAL TRANSACTIONS IN OPERATIONAL RESEARCH

Abstract
Distribution warehouses are a critical part of supply chains, representing a nonnegligible share of the operating costs. This is especially true for unautomated, labor-intensive warehouses, partially due to time-consuming activities such as picking up items or traveling. Inventory categorization techniques, as well as zone storage assignment policies, may help in improving operations, but may also be short-sighted. This work presents a three-step methodology that uses probabilistic simulation, optimization, and event-based simulation (SOS) to analyze and experiment with layout and storage assignment policies to improve the picking performance. In the first stage, picking performance is estimated under different storage assignment policies and zone configurations using a probabilistic model. In the second stage, a mixed integer optimization model defines the overall warehouse layout by selecting the configuration and storage assignment policy for each zone. Finally, the optimized layout solution is tested under demand uncertainty in the third, final simulation phase, through a discrete-event simulation model. The SOS methodology was validated with three months of operational data from a large retailer's warehouse, successfully illustrating how it may be successfully used for improving the performance of a distribution warehouse.

2019

Solving a large multi-product production-Routing problem with delivery time windows

Authors
Neves Moreira, F; Almada Lobo, B; Cordeau, JF; Guimaraes, L; Jans, R;

Publication
Omega

Abstract

2019

Tackling perishability in multi-level process industries

Authors
Wei, WC; Amorim, P; Guimaraes, L; Almada Lobo, B;

Publication
International Journal of Production Research

Abstract
The classical multi-level lot-sizing and scheduling problem formulations for process industries rarely address perishability issues, such as limited shelf lives of intermediate products. In some industries, ignoring this specificity may result in severe losses. In this paper, we start by extending a classical multi-level lot-sizing and scheduling problem formulation (MLGLSP) to incorporate perishability issues. We further demonstrate that with the objective of minimising the total costs (purchasing, inventory and setup), the production plans generated by classical models are often infeasible under a setting with perishable products. The model distinguishes different perishability characteristics of raw materials, intermediates and end products according to various industries. Finally, we provide quantitative insights on the importance of considering perishability for different production settings when solving integrated production planning and scheduling problems. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.

2018

Allocating products on shelves under merchandising rules: Multi-level product families with display directions

Authors
Bianchi Aguiar, T; Silva, E; Guimardes, L; Carravilla, MA; Oliveira, JF;

Publication
Omega (United Kingdom)

Abstract
Retailers’ individual products are categorized as part of product families. Merchandising rules specify how the products should be arranged on the shelves using product families, creating more structured displays capable of increasing the viewers’ attention. This paper presents a novel mixed integer programming formulation for the Shelf Space Allocation Problem considering two innovative features emerging from merchandising rules: hierarchical product families and display directions. The formulation uses single commodity flow constraints to model product sequencing and explores the product families’ hierarchy to reduce the combinatorial nature of the problem. Based on the formulation, a mathematical programming-based heuristic was also developed that uses product families to decompose the problem into a sequence of sub-problems. To improve performance, its original design was adapted following two directions: recovery from infeasible solutions and reduction of solution times. A new set of real case benchmark instances is also provided, which was used to assess the formulation and the matheuristic. This approach will allow retailers to efficiently create planograms capable of following merchandising rules and optimizing shelf space revenue. © 2017 Elsevier Ltd

2018

The time window assignment vehicle routing problem with product dependent deliveries

Authors
Neves Moreira, F; da Silva, DP; Guimaraes, L; Amorim, P; Almada Lobo, B;

Publication
Transportation Research Part E: Logistics and Transportation Review

Abstract

Supervised
thesis

2020

Product line selection in fast-moving consumer goods industries

Author
Xavier António Reis Andrade

Institution
UP-FEUP

2020

Modelo de Custeio e Investimento para uma Nova Linha de Montagem numa Empresa de Packaging de Semicondutores

Author
Luís Pedro Silva Manso-Preto Rodrigues

Institution
UP-FEUP

2020

Comparação, cronometragem e balanceamento da produção de estruturas na indústria automóvel

Author
Hugo Filipe Dias Salvador

Institution
UP-FEUP

2020

Reestruturação do Supply Network Plan numa Empresa de Painéis Derivados de Madeira

Author
Rui Fernando Teixeira da Silva Macedo

Institution
UP-FEUP

2020

Optimizing O&M plans for flexible hydropower systems

Author
Xavier Tarrio Fernandes

Institution
UP-FEUP