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Sobre

Sobre

Elsa Silva é investigadora no Centro de Engenharia e Gestão Industrial do INESC TEC e Professora Auxiliar convidada do Departamento de Produção e Sistemas da Universidade do Minho.

É doutorada em Engenharia Industrial e de Sistemas desde 2012 pela Universidade do Minho. Os seus principais interesses de investigação incluem a capacidade de resolver problemas de optimização combinatória difíceis e de grande escala que surgem em várias áreas, tais como problemas de corte e empacotamento e operações de retalho, utilizando abordagens híbridas de programação linear e meta-heurísticas.

As principais contribuições da investigação da Elsa Silva têm sido em problemas de corte e empacotamento (C&P). Algoritmos pioneiros foram desenvolvidos combinando modelos matemáticos, métodos de decomposição e heurísticas para resolver aplicações práticas que até agora não foram estudadas realisticamente. Esta foi uma contribuição importante para o avanço do conhecimento na área dos C&P.

As aplicações práticas abordadas foram: Problema de Alocação de Espaço em Prateleira, Problema de Empacotamento de Tiras na indústria têxtil, Problema de Carregamento de Contentores com estabilidade, limite de peso, balanceamento de carga e restrições de entregas múltiplas. Outra contribuição importante na área de C&P foi o gerador de instâncias para todos os tipos de problemas de C&P retangulares 2D e 3D.

Tópicos
de interesse
Detalhes

Detalhes

  • Nome

    Elsa Marília Silva
  • Cargo

    Investigador Colaborador Externo
  • Desde

    01 fevereiro 2012
006
Publicações

2026

Covering with Network Design for Wildfire Promptness

Autores
Silva, E; e Alvelos, eF; Marto, M;

Publicação
Lecture Notes in Operations Research

Abstract
We consider the problem of selecting bases for firefighting activities (e.g., vigilance, water refill, initial attack) and links between them in the context of wildfire promptness. Bases can be facilities, such as watchtowers and water tanks, or positions from where an initial attack is conducted. It is assumed that it is advantageous to connect bases in such a way that resources (e.g. ground crews) can quickly move between them. The general problem is modelled in a general way as integration of a set covering problem (for selecting the location of the bases) and a travelling salesman problem where the cities are the selected locations and the arcs the links that connect them. We propose a mixed integer programming model where objectives are addressed by lexicographic optimization. The first objective is related to cover potential ignition points with a high estimate of their initial spread rate of the fire at the detection time. Computational experiments are discussed for a scenario, of an actual landscape, with parameters estimated from a fire behaviour model that takes into account slope, fuels, and wind. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2026.

2025

A 3D printing nesting algorithm with dynamic collision constraints

Autores
Rocha, P; Ramos, AG; Silva, E;

Publicação
INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH

Abstract
Additive Layer Manufacturing, particularly Fused Deposition Modelling, faces significant batch loss risks during production. The traditional Concurrent Printing Mode produces all parts simultaneously (layer-by-layer, bottom-to-top), efficiently using printing space but risking complete batch failure if problems occur. In contrast, Sequential Printing Mode produces one part at a time, reducing the risk of total batch loss but utilising printing space less efficiently. In this work, we propose an algorithm that, given a set of parts, performs the nesting of the parts for Concurrent Printing Mode, and for the first time, for the Sequential Printing Mode. A no-fit polygon based approach is used to handle geometry between pairs of parts by using multiple horizontal 2D layer projections of 3D parts, to ensure non-overlapping constraints and prevent machine-part collisions. A Greedy Randomized Adaptive Search Procedure is proposed, tested and benchmarked against a commercial software, using a new set of real-world instances. The approach shows the ability to find high-quality solutions. The approach significantly reduces the number of batches, minimises waste, reduces manufacturing time, and promotes parts quality.

2025

Improving warehouse operations: leveraging simulation for efficient layout design and process improvement in a picking by line operation

Autores
de Carvalho Paula, M; Carvalho, MS; Silva, E;

Publicação
Procedia Computer Science

Abstract
This study focuses on improving the picking processes within a Picking-by-Line (PBL) warehouse through the development of a simulation model to assess different layouts and new operational rules. Utilizing a combination of Discrete Event Simulation (DES) and Agent-Based Modeling (ABS) in AnyLogic, the simulation model was validated against real-world Key Performance Indicators (KPIs) to ensure accuracy. The study identified three primary improvement opportunities. To address these opportunities, four scenarios were tested. The results showed varying impacts on productivity, with three of the four scenarios yielding improvements in picking productivity. Pilot testing confirmed the simulation model's predictions. The findings indicate that balancing travel distance reduction with congestion management is key to increasing picking productivity. This study reaffirms the value of simulation modeling in warehouse management, providing a robust framework for free-risk testing. © 2025 Elsevier B.V., All rights reserved.

2025

Anew effective heuristic for the Prisoner Transportation Problem

Autores
Ferreira, L; Maciel, MVM; de Carvalho, JV; Silva, E; Alvelos, FP;

Publicação
EUROPEAN JOURNAL OF OPERATIONAL RESEARCH

Abstract
The Prisoner Transportation Problem is an NP-hard combinatorial problem and a complex variant of the Dial-a- Ride Problem. Given a set of requests for pick-up and delivery and a homogeneous fleet, it consists of assigning requests to vehicles to serve all requests, respecting the problem constraints such as route duration, capacity, ride time, time windows, multi-compartment assignment of conflicting prisoners and simultaneous services in order to optimize a given objective function. In this paper, we present anew solution framework to address this problem that leads to an efficient heuristic. A comparison with computational results from previous papers shows that the heuristic is very competitive for some classes of benchmark instances from the literature and clearly superior in the remaining cases. Finally, suggestions for future studies are presented.

2025

A GRASP-based multi-objective approach for the tuna purse seine fishing fleet routing problem

Autores
Granado, I; Silva, E; Carravilla, MA; Oliveira, JF; Hernando, L; Fernandes Salvador, JA;

Publicação
COMPUTERS & OPERATIONS RESEARCH

Abstract
Nowadays, the world's fishing fleet uses 20% more fuel to catch the same amount offish compared to 30 years ago. Addressing this negative environmental and economic performance is crucial due to stricter emission regulations, rising fuel costs, and predicted declines in fish biomass and body sizes due to climate change. Investment in more efficient engines, larger ships and better fuel has been the main response, but this is only feasible in the long term at high infrastructure cost. An alternative is to optimize operations such as the routing of a fleet, which is an extremely complex problem due to its dynamic (time-dependent) moving target characteristics. To date, no other scientific work has approached this problem in its full complexity, i.e., as a dynamic vehicle routing problem with multiple time windows and moving targets. In this paper, two bi-objective mixed linear integer programming (MIP) models are presented, one for the static variant and another for the time-dependent variant. The bi-objective approaches allow to trade off the economic (e.g., probability of high catches) and environmental (e.g., fuel consumption) objectives. To overcome the limitations of exact solutions of the MIP models, a greedy randomized adaptive search procedure for the multi-objective problem (MO-GRASP) is proposed. The computational experiments demonstrate the good performance of the MO-GRASP algorithm with clearly different results when the importance of each objective is varied. In addition, computational experiments conducted on historical data prove the feasibility of applying the MO-GRASP algorithm in a real context and explore the benefits of joint planning (collaborative approach) compared to a non-collaborative strategy. Collaborative approaches enable the definition of better routes that may select slightly worse fishing and planting areas (2.9%), but in exchange fora significant reduction in fuel consumption (17.3%) and time at sea (10.1%) compared to non-collaborative strategies. The final experiment examines the importance of the collaborative approach when the number of available drifting fishing aggregation devices (dFADs) per vessel is reduced.