One key condition in these retailer-supplier agreements is the Minimum Life On Receipt (MLOR) rule, which defines the maximum product age acceptable by the retailer to pay the full price. In this study, we propose a model that helps negotiate the retailer-supplier agreement's conditions to make them more flexible. Specifically, we define the share of orders that may be accepted by the retailer...
In this work, a hyperparameter (kernel and C) optimization model for a support vector machine (SVM) classifier applied to handwritten digit recognition is presented. The kernel determines how the data is transformed and separated, which directly affects the model’s ability to capture complex patterns. The regularization parameter controls the balance between fitting the training data and...
Hybrid offshore renewable energy systems (HRES) offer a promising solution to mitigate the variability of renewable energy sources. Specifically, combining offshore wind turbines, solar photovoltaics, and wave energy converters enhances power stability by leveraging their complementary characteristics. However, designing an efficient HRES requires a comprehensive approach that addresses key...
O setor bancário europeu atravessou um período de profundas transformações entre 2014 e 2022, impulsionado por choques como a pandemia de COVID-19, regulamentações supranacionais e a aceleração digital. Este estudo analisa a eficiência operacional de 96 bancos sistémicos sob supervisão direta do Banco Central Europeu, utilizando a metodologia Value-Based Data Envelopment Analysis e Window...
This work addresses the Integrated Production Routing Problem (IPRP), a challenging combinatorial optimization problem inspired by the real-world operations of a Brazilian furniture manufacturer. The IPRP involves coordinating production and distribution decisions over a finite planning horizon, divided into periods, for multiple products characterized by heterogeneous attributes, such as...
This work addresses the Multi-Compartment Vehicle Routing Problem (MCVRP), relevant for transporting goods that must remain separated or require distinct temperature conditions. We consider a predefined fleet consisting of three vehicle types: room temperature, refrigerated, and dual-compartment (room temperature and refrigerated). The distribution scenario involves multiple pick-up points and...
Sustainability challenges have become a central concern in supply chain design and planning, requiring effective decision-support methods that address economic, environmental, and social objectives. This work proposes a hybrid optimization–simulation framework that combines a mixed-integer linear programming model, used to optimize sustainability goals through a novel practically oriented...
Earth Observation Satellites (EOSs) are designed to collect images of Earth’s surface for a wide range of applications, such as disaster response, environmental monitoring and resource management. With the increasing number of orbiting EOSs, efficient scheduling of satellite operations has become a critical challenge. To ensure effective use of these complex systems, it is essential to develop...
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...
Derivative-free methods—also known as black-box or zero-order methods—are crucial when derivative information is unavailable or unreliable. We introduce a novel algorithm that, for nonsmooth convex objectives, achieves a worst-case complexity bound proportional to the inverse square of a specified accuracy tolerance—substantially improving over a previously developed method in the literature....
Pickup and Delivery Problems (PDP) and their variants are commonly found in logistics and transportation systems. This work addresses a logistic transport problem where homogeneous vehicles must fulfill transportation requests between pickup and delivery nodes, subject to service level agreements (SLAs). We compare the performance of two Mixed-Integer Linear Programming (MILP) models: one...
Wildfires pose a significant threat to ecosystems, frequently having detrimental effects on the environment and the economy. One of the main reasons for their ignition and propagation is the abundance of unmanaged vegetation, particularly close to linear infrastructures. Countries prone to these hazards have established fuel lane management strategies to mitigate fire risks. Fuel lane...
The rapid expansion of e-commerce has placed unprecedented pressure on urban logistics: Last-Mile Delivery (LMD) now poses a significant environmental impact contributing to over 30% of total CO2 emissions in the delivery sector and worsening congestion. We propose a Green Two-Echelon Location-Routing Problem (G2E-LRP), explicitly integrating (i) a heterogeneous fleet with both conventional...
We propose an effective hybrid decomposition method to solve network-constrained stochastic unit commitment (SNCUC) problems. We address large-scale SNUC cases involving renewable generation units, hundreds of thermal generation units, thousands of transmission lines and nodes, and uncertain renewable generation and demand. The problem is formulated as a two-stage stochastic program with...
Plantations face significant challenges due to water scarcity and prolonged periods of drought. Currently, irrigation management is mostly performed manually and relies heavily on the experience of farmers, who make adjustments based on the time of year. However, several factors influence irrigation needs, including air and soil humidity, temperature, and the amount of rainfall. Incorporating...
Demand-responsive transport (DRT) systems are quite flexible, adapting quickly to changes in demand through dynamic routing, scheduling, and fleet sizing. Unlike conventional public transport, DRT operations are often planned daily, especially in low-demand contexts. However, as demand grows, planning becomes computationally intensive. While effective methods exist in the literature, many are...
Este trabalho apresenta, do ponto de vista de um grupo de estudantes da Licenciatura em Gestão Industrial e Logística da ESTG, P.PORTO, uma experiência de integração da gamificação no ensino da modelação matemática, através de um Trabalho Prático que tem como ponto de partida o Burrito Optimization Game, desenvolvido pela Gurobi (https://www.gurobi.com/burrito-optimization-game/). O trabalho...
A pandemia de COVID-19 provocou mudanças significativas no ensino superior, obrigando as universidades a adaptarem-se rapidamente ao ensino remoto e à gestão eficiente de recursos. A crise colocou à prova a capacidade das instituições de rever processos, otimizar o uso de recursos e manter a qualidade do ensino e da investigação.
Este trabalho tem como objetivo avaliar a eficiência do ensino...
A pobreza energética permanece uma preocupação relevante na União Europeia, agravada pela falta de uma definição harmonizada e de metodologias comparáveis entre países. Este estudo propõe a construção de um indicador composto e multidimensional, com base no modelo Value-Based Data Envelopment Analysis e na sua extensão dinâmica Window Analysis, complementado pela abordagem de Club Convergence....
Online marketplaces provide a platform that connects suppliers with customers, allowing vendors to sell their products to a broader audience. To streamline customer experience, some marketplaces allocate a set of fulfillment vendors and stockpoints at the moment a customer is placing an order in the platform. This order allocation decision impacts not only fulfillment costs and customer...
The Vehicle Routing Problem and its many variants have been extensively studied over the years due to the various gains enabled by efficient route planning. However, many routing models consider cost minimization by focusing solely on factors such as distance traveled or the number of vehicles utilized, often neglecting other considerations that affect costs and disregarding the environmental...
Apesar do compromisso do Brasil em atingir a Fome Zero (2o. Objetivo de Desenvolvimento Sustentável da ONU), o país retornou ao mapa da fome em 2022. Nas cidades brasileiras, é muito comum termos várias instituições civis e religiosas que distribuem cestas de alimentos para famílias em situação de vulnerabilidade. Uma cesta de alimentos, chamada de cesta básica, contém um conjunto de alimentos...
Growing environmental concerns and increasingly stringent regulations have compelled supply chains (SC) to rethink how they distribute the costs of environmental impacts. However, this is a complex challenge, especially when trying to balance sustainability with financial performance and fair cost-sharing among stakeholders. This paper addresses this challenge by developing a decision support...
Trust is a key determinant of successful human-robot interaction across diverse application domains. This study investigates the formation of trust in robots through an online experiment where participants viewed curated videos showcasing varied robotic behaviors. Conducted within the I-CATER project, which focuses on social robots in workplace environments, the research explores how...
Hydrogen is a key element in the global transition toward a low-carbon economy, with green hydrogen offering significant potential to decarbonize industries and energy systems. This study aims to develop a decision support system for the optimized implementation of a Hydrogen Supply Chain (HSC) in Brazil. Key aspects identified in the literature will be addressed, including the need for...
The design of modern supply chains should account for stimulating economic growth by establishing efficient material and information flows. Yet, the same economic growth trend that fuels supply chains is also contributing to the unsustainable use of resources. This challenge provides the conceptual leverage for this work: to model the government’s role as a central agent in the transition...
As infeções associadas aos cuidados de saúde representam uma ameaça significativa à saúde pública, agravada pela sua resistência antimicrobiana. Métodos tradicionais de deteção apresentam várias limitações, incluindo baixa sensibilidade e custos elevados. Uma alternativa promissora é a deteção de compostos orgânicos voláteis (VOCs) emitidos por bactérias, que atuam como uma “impressão digital”...
The interdependence of nesting and production scheduling problems in Additive Manufacturing (AM) systems poses a significant computational challenge when considering traditional optimization methods. This work addresses the AM scheduling problem (AMSP), with a particular focus on the nesting component, which remains the major computational bottleneck in existing approaches. Current nesting...
Maritime transport and port operations are vital to global trade but face growing pressure to improve efficiency and lower greenhouse gas (GHG) emissions. Just-in-Time (JIT) arrival offers a promising management solution, involving speed adjustments so that vessels reach the pilot boarding point only when port services are confirmed. This approach aims to cut fuel and emissions by reducing...
The stochastic dynamic inventory-routing problem (SDIRP) integrates inventory management and vehicle routing under uncertainty, where customer demands are revealed progressively over time.
This research aims to provide new insights into resolving an SDIRP, focusing on a central warehouse that periodically distributes homogeneous goods to a set of geographically dispersed...
Efficient cost and resource allocation in healthcare is essential for the sustainability of hospital operations and patient-centered initiatives. However, this can be a complex issue due to the extensive scope of work and the difficulty in maintaining economic models designed for these evaluations. In recent years, machine learning (ML) has been increasingly adopted to support healthcare...
This study tackles the fleet composition problem for a transport operator facing uncertainties in energy prices, vehicle costs, and operational expenses over a defined planning horizon. With a limited budget, the decision-maker must choose among vehicle types—such as diesel with lower upfront costs but higher running expenses, and electric with the opposite profile.
To manage long-term cost...
Abstract
The growing uncertainty of the international economic and political landscape, accentuated by phenomena such as Brexit and the pandemic, highlights the importance of robust and interpretable decision-support tools. In this environment, operational research (OR) is crucial for designing sustainable and innovative solutions for both society and businesses. This study contributes to...
This study analyzes the waste collection operations of the municipality of Figueira da Foz, Portugal, using real operational data from February 2020 to April 2024. The objective is to evaluate and optimize the current system through four distinct scenarios. First, we establish a baseline by examining the existing system, which operates on fixed schedules and routes - a method commonly referred...
Financial literacy is essential for the well-being and social inclusion of individuals of all ages, but its absence is particularly detrimental to young people. Portuguese students exhibit significant shortcomings in this area, largely due to the lack of structured instruction during compulsory education. This study applies the Analytic Hierarchy Process (AHP) to rank pedagogical strategies...
Current methods in product development and industrialization are rigid, resource-intensive, and reliant on expert intuition. Integrating Artificial Intelligence (AI), particularly Generative AI (GenAI), with combinatorial optimization presents significant potential to address these challenges. Such integration can enable data-driven, automated decision-making across the product lifecycle—from...
Increasing performance while minimizing operational risk is essential for successful logistics operations. However, these objectives often conflict—particularly in distribution centers, where picking operators are exposed to fatigue and injury risks that compromise both safety and individual efficiency. This study presents a first modelling approach to address this trade-off, based on a...
Maritime trade has been continuously growing in the last decades, increasing the pressure on container terminals and intensifying needs for more effective management systems. Inefficiency arises on the land-side operations with the increasing number of truck arrivals for the collection and delivery of containers. The highly stochastic nature of truck arrivals leads to an unbalanced workload...
This study addresses the routing for the inspection of electric lines with drones in Portugal, managed by EDP Labelec, the partner company in this project. There is a set of electrical lines that need to be inspected and a set of points where the drone operator can stop managing the drone for inspecting those lines. The objective is to determine an inspection plan — that is, the points where...
The transition to renewable energy presents significant challenges in managing production and consumption efficiently. This study addresses the optimization of the energy usage for owners of photovoltaic plants equipped with storage systems. The main objective is to develop a decision-support model that maximizes profitability by intelligently and dynamically managing consumption and storage...
Urbanization is accelerating, creating challenges in transportation, energy use, and emissions. Car-sharing can lower private car ownership and greenhouse gas emissions, while electric vehicles (EVs) produce zero emissions and can use renewable energy. Combining EVs with car-sharing offers a sustainable transport solution. However, the rising electricity demand from widespread EV adoption may...
Retailers’ product mix selection is a key determinant of market share, profitability, and long-term success. While a broader assortment increases the likelihood of meeting diverse customer preferences, it raises inventory-related costs and stockout risks, ultimately affecting operational performance and customer loyalty. This challenge is amplified for perishable goods, where limited shelf...
This work addresses the problem of estimating the conditional survival function when event times are subject to interval censoring and continuous covariates are present. Such data structures arise frequently in real-world operational contexts, including maintenance planning, healthcare monitoring, and quality control systems, where events are only observed within time intervals due to periodic...
Nowadays, companies desire to offer customised products and services to their customers. At the same time, they want to address customers’ requests as fast as possible. In addition, operations are often subject to high uncertainty and frequent disruptions, such as urgent order arrivals, resource unavailability, and product defects. Under these conditions, companies need to schedule tasks...
Este estudo propõe um modelo de otimização multi-período para um problema de Gestão da Cadeia de Abastecimento de Biomassa Residual. O modelo aborda os desafios associados à acumulação de biomassa, à logística de transporte e à capacidade de armazenamento, assegurando simultaneamente a viabilidade económica. É utilizada uma abordagem de otimização robusta baseada em cenários para ter em conta...
This work addresses the design of networks to support wildfire preparedness activities, namely surveillance, detection, and suppression. The problem is defined over a graph where nodes represent potential locations for positioning resources (e.g., watchtowers or firefighting crews), and arcs denote direct connections (e.g., roads) between these locations.
We propose a mixed-integer...
Monte Carlo tree search (MCTS) has shown significant success in game playing, achieving state-of-the-art results in many complex domains. While there are known applications in optimization, they often don't fully capitalize on the problem-specific knowledge available. This work addresses this gap by proposing adaptations of MCTS tailored for optimization problems. We focus on enhancing the...
Os impactos causados pelos resíduos de construção e demolição (RCD) podem ser elevados caso não se efetue uma gestão eficaz dos mesmos. Em consequência, as preocupações relacionadas com esta gestão têm aumentado nos últimos anos, estimulando a elaboração de estudos sobre o assunto.
Este trabalho deu continuidade aos trabalhos de Correia (2013) e Andrade (2015), que desenvolveram uma nova...
Esta comunicação explora o ensino da Investigação Operacional (IO) a partir da perspetiva dos estudantes, procurando fomentar uma reflexão crítica e informada sobre as práticas pedagógicas nesta área. A metodologia integra o testemunho de uma antiga aluna — que partilha os principais desafios e fatores de motivação vivenciados — e a análise preliminar de um questionário atualmente em curso...
The Vehicle Routing Problem (VRP) is a fundamental combinatorial optimization challenge with wide-ranging applications in logistics and transportation. While machine learning has recently gained traction as a scalable alternative to traditional solvers, most existing methods are designed for a single specific VRP variant, limiting their generalizability to solve a diverse range of VRP...
"Submissão EstudIO"
The insect-production industry has been growing rapidly, creating a demand for new decision-support tools. Locating insect-production facilities, however, is difficult because site choice directly affects the cost savings and sustainability benefits that can be achieved. A poor location can undermine a project: if a plant is not close to sources of insect feed, transporting the necessary...
In this presentation, we address the vehicle routing problem with time windows and synchronized visits under uncertain service and travel times. Specifically, a subset of clients require simultaneous service by two vehicles, which is initiated only after the arrival of both vehicles and, consequently, enforces a waiting period for the vehicle that arrived earlier. To tackle this problem, we...
Desde o final da década de 1950 que a Investigação Operacional tem contribuido para a gestão de incêndios florestais. Em anos recentes, têm sido propostas diversas aborgadens para o problema de supressão que, genericamente, consiste em decidir onde colocar os meios disponíveis para atacar o incêndio da forma mais consequente.
Nesta apresentação discutem-se abordagens baseadas em programação...
A gestão eficiente do processo produtivo numa unidade de descasque, transformação e embalamento de arroz enfrenta diversos desafios operacionais e logísticos, que se traduzem em pontos críticos. Estes problemas podem ser agrupados em três grandes dimensões: a matéria-prima (arroz), a estrutura produtiva e a capacidade de armazenamento. Relativamente ao arroz, surgem várias restrições que...
Os modelos de otimização desempenham um papel essencial em ambientes industriais, especialmente na Indústria 5.0, onde os sistemas robóticos avançados são fundamentais para aumentar a eficiência e a adaptabilidade. Este trabalho aborda problemas de otimização de grande escala e altamente não lineares, que surgem na geração de movimentos semelhantes aos humanos para um robô antropomórfico a...
The Amazon River and its tributaries form an extensive and complex network exceeding 10,000 km, comprising several significant tributaries. These rivers are crucial for connectivity, facilitating trade and commerce, and providing access to services for local communities. Patrolling these waterways is essential to curb illegal activities, protect biodiversity, and safeguard local communities....
Health systems are under growing pressure due to resource constraints and increasing demand. Measuring hospital efficiency is therefore crucial to support effective management and evidence-based policymaking. This study introduces an innovative framework that combines Data Envelopment Analysis (DEA) with machine learning (ML) techniques to assess and predict the efficiency of Portuguese public...
In pursuit of a more sustainable future, populations and economies need to be protected by stronger and more resilient health systems. Their complexity requests adequate assessment frameworks for improving the access and quality of their services. Due to the multidimensional nature of health systems, this study presents a collaborative multi-criteria decision-aiding framework to assess the...
No problema de escalonamento cíclico de turnos com rotação de folgas e horários fixos o objetivo é alocar trabalhadores em ciclos que combinem turnos fixos (manhã, tarde, noite) e folgas rotativas, garantindo operações ininterruptas em setores como saúde e indústria. O problema envolve elevada complexidade computacional (sendo classificado como NP-difícil) devido a múltiplas restrições: legais...
The rolling stock rotation planning problem with maintenance constraints can be stated in the following way: given a set of train trips each one with its own passenger demand find, from scratch, for a standard week, the most cost-effective rotations that assign a vehicle composition (hereafter composition) to each trip that covers all or part of the demand and that satisfy all operational...
This work focuses on planning daily routes for a group of employees from a condominium company.
Given a set of employees and a set of customers with pre-scheduled visits, we want to build double-open routes to guarantee visits to all customers, ensuring that each customer is visited by an employee with the appropriate skills to carry out the required activity. The travel times between...
The crew reserve duty scheduling problem involves generating reserve duties months in advance.
These duties are daily periods where crew members are on call at their operational bases, ready to perform jobs assigned to them by dispatchers, that are handling disruptions typically during the day of operation.
This optimisation problem is challenging because the exact time and place where a...
Um {\em clutter\/} é um par ${\cal C} \equiv (V,E)$, onde $E$ (os elementos de $\Cl$) denota uma família de subconjuntos, de um conjunto não vazio e finito $V$ (os vértices de $\Cl$),
tal que nenhum dos elementos está contido noutro.
A teoria de clutters, outrora referida como {\em blocking\/} e {\em antiblocking\/} (Fulkerson'70), permite abordar, de modo elegante, questões diversas...
Business incubators are often seen as essential tools for fostering startup success and driving regional economic development. But how much of that impact is real, and how much is assumed? In this plenary session, I will share a reflection grounded in empirical data and hands-on experience on how incubation programs can — or sometimes cannot — make a meaningful difference for startups.
We...
This study addresses the Waste Collection Vehicle Routing Problem with Profit (WCVRP) while considering uncertainty in bin fill levels a critical challenge for municipalities and waste management providers aiming to enhance service efficiency. In real-world conditions, bins fill levels fluctuate unpredictably, leading to inefficient routing, unnecessary trips, or uncollected waste. To tackle...
The recovery of food waste is a trend in the current context of sustainability, circular economy, and waste reduction. For example, it is possible to use peels, seeds, and non-standard fruit to produce new products such as jams, teas, flour, or transform them into animal feed, biofertilizers, or cosmetics. The literature on food waste and losses along the food supply chain is vast, but...
Omnichannel grocery retailers often use stores to fulfill online orders for a variety of reasons (e.g., faster deliveries, labor availability). This strategy influences inventory management, particularly the spoilage ratio (defined as the ratio of loss to sales) in two opposing ways. Fulfilling online orders has the potential to increase the sales-to-stock ratio thereby improving turnover...
The mining industry plays a crucial role in the global energy transition, which is essential for achieving net-zero carbon emissions. As the main source of critical minerals essential to renewable energy technologies, mining supplies the foundational materials needed for the development and deployment of clean energy solutions. Consequently, the demand for these minerals is projected to grow...
The Traveling Purchaser Problem with Incompatibility Constraints (TPP-IC) generalizes the classical Traveling Purchaser Problem (TPP) by introducing constraints that prevent certain items from being transported together. This problem arises in various real-world applications, such as hazardous materials transportation, where incompatible products must be handled separately to ensure safety and...
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A flexibilidade é fundamental para a gestão de sistemas de energia, tendo como objetivo incentivar a alteração dos padrões de consumo de eletricidade face à crescente produção renovável variável. Os agregadores desempenham um papel importante, recolhendo a flexibilidade dos consumidores/produtores, que pode depois ser transacionada em mercados, criando benefícios económicos e operacionais para...
The 2030 Agenda for Sustainable Development presents an ambitious call to action for ending poverty, improving health and well-being, and addressing the climate emergency. These global challenges are especially acute in the Global South, where systemic vulnerabilities and resource constraints demand innovative, context-sensitive solutions. Operational Research, and optimisation in particular,...
Labor costs account for a significant portion of operational expenses in the food retail sector, making workforce optimization a strategic priority. This work develops a data-driven methodology to determine the optimal number of Full-Time Equivalents (FTEs) needed per store, function, and week, balancing operational efficiency with service level. The proposed framework consists of two...
