This paper addresses the problem of energy-efficient and safe routing of last-mile electric freight vehicles. With the rising environmental footprint of the transportation sector and the growing popularity of E-Commerce, freight companies are likely to benefit from optimal time window feasible tours that minimize energy usage while reducing traffic conflicts at intersections and thereby improving safety. We formulate this problem as a Bi-criterion Steiner Traveling Salesperson Problem with Time Windows (BSTSPTW) with energy consumed and the number of left turns at intersections as the two objectives while also considering regenerative braking capabilities. We first discuss an exact mixed-integer programming model with scalarization to enumerate points on the efficiency frontier for small instances. For larger networks, we develop an efficient local search-based heuristic, which uses several operators to intensify and diversify the search process. We demonstrate the utility of the proposed methods using benchmark data and real-world instances from Amazon delivery routes in Austin, US. Comparisons with state-of-the-art solvers show that our heuristics can generate near-optimal solutions within reasonable time budgets, effectively balancing energy efficiency and safety under practical delivery constraints.
{"title":"A Bi-criterion Steiner Traveling Salesperson Problem with Time Windows for Last-mile Electric Vehicle Logistics","authors":"Prateek Agarwal , Debojjal Bagchi , Tarun Rambha , Venktesh Pandey","doi":"10.1016/j.cor.2025.107286","DOIUrl":"10.1016/j.cor.2025.107286","url":null,"abstract":"<div><div>This paper addresses the problem of energy-efficient and safe routing of last-mile electric freight vehicles. With the rising environmental footprint of the transportation sector and the growing popularity of E-Commerce, freight companies are likely to benefit from optimal time window feasible tours that minimize energy usage while reducing traffic conflicts at intersections and thereby improving safety. We formulate this problem as a Bi-criterion Steiner Traveling Salesperson Problem with Time Windows (BSTSPTW) with energy consumed and the number of left turns at intersections as the two objectives while also considering regenerative braking capabilities. We first discuss an exact mixed-integer programming model with scalarization to enumerate points on the efficiency frontier for small instances. For larger networks, we develop an efficient local search-based heuristic, which uses several operators to intensify and diversify the search process. We demonstrate the utility of the proposed methods using benchmark data and real-world instances from Amazon delivery routes in Austin, US. Comparisons with state-of-the-art solvers show that our heuristics can generate near-optimal solutions within reasonable time budgets, effectively balancing energy efficiency and safety under practical delivery constraints.</div></div>","PeriodicalId":10542,"journal":{"name":"Computers & Operations Research","volume":"185 ","pages":"Article 107286"},"PeriodicalIF":4.3,"publicationDate":"2025-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145262458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-04DOI: 10.1016/j.cor.2025.107288
Wendi Li , Gang Du , Xiaohang Yue
Home healthcare plays a key role in the era of an aging population and limited healthcare resources in hospitals, and one of its important tasks is to develop optimal caregiver visit routines. In the context of sustainable development and dual carbon goals, home healthcare must also address carbon emissions during caregiver visits. One of the most effective initiatives is the use of electric vehicles to gradually replace fuel vehicles as an important means of transportation. Therefore, this paper investigates a multi-objective home healthcare path optimization problem based on a mixed fleet of vehicles. In this problem, the transportation of caregivers is either electric or fuel vehicles, and this paper considers the case of patients with different numbers of multiple time windows, defines compatibility, and optimizes five conflicting objectives under the constraints of time windows, doctor-patient skill matching, electric vehicle battery capacity, compatibility, and maximum working hours. To address this problem, we develop a mixed integer programming model to optimize five objectives: cost minimization, caregiver utilization maximization, workload deviation minimization, patient-caregiver compatibility maximization, and skill level deviation minimization. In addition, this paper proposes a hybrid algorithmic solution model with hybrid simulated annealing and a third-generation non-dominated sorting genetic algorithm and designs two neighborhood structures based on the problem characteristics as well as heuristics for charging station insertion. The results show that the improved hybrid algorithm solves the problem more comprehensively and effectively and can cover a wider solution space with good distribution and diversity.
{"title":"A multi-time-window multi-objective hybrid fleet home health care routing optimization problem considering caregiver utilization and compatibility","authors":"Wendi Li , Gang Du , Xiaohang Yue","doi":"10.1016/j.cor.2025.107288","DOIUrl":"10.1016/j.cor.2025.107288","url":null,"abstract":"<div><div>Home healthcare plays a key role in the era of an aging population and limited healthcare resources in hospitals, and one of its important tasks is to develop optimal caregiver visit routines. In the context of sustainable development and dual carbon goals, home healthcare must also address carbon emissions during caregiver visits. One of the most effective initiatives is the use of electric vehicles to gradually replace fuel vehicles as an important means of transportation. Therefore, this paper investigates a multi-objective home healthcare path optimization problem based on a mixed fleet of vehicles. In this problem, the transportation of caregivers is either electric or fuel vehicles, and this paper considers the case of patients with different numbers of multiple time windows, defines compatibility, and optimizes five conflicting objectives under the constraints of time windows, doctor-patient skill matching, electric vehicle battery capacity, compatibility, and maximum working hours. To address this problem, we develop a mixed integer programming model to optimize five objectives: cost minimization, caregiver utilization maximization, workload deviation minimization, patient-caregiver compatibility maximization, and skill level deviation minimization. In addition, this paper proposes a hybrid algorithmic solution model with hybrid simulated annealing and a third-generation non-dominated sorting genetic algorithm and designs two neighborhood structures based on the problem characteristics as well as heuristics for charging station insertion. The results show that the improved hybrid algorithm solves the problem more comprehensively and effectively and can cover a wider solution space with good distribution and diversity.</div></div>","PeriodicalId":10542,"journal":{"name":"Computers & Operations Research","volume":"185 ","pages":"Article 107288"},"PeriodicalIF":4.3,"publicationDate":"2025-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145262360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-03DOI: 10.1016/j.cor.2025.107293
Zheng Wang , Pingyuan Dong , Ying Liu
The complexity incorporated in global supply chain (GSC) means the production, transportation, and delivery are totally operating and completing in the dynamic business environment with unforeseen events. At present, there are two key challenges in the transnational supply chain network: addressing the demand ambiguity and enhancing cooperation among supply chain entities. To optimize the production–transportation–delivery decision in GSC, a novel globalized distributionally robust GSC (GDR-GSC) model with horizontal cooperation is proposed, in which the ambiguity of demand distribution is characterized by inner and outer ambiguity sets. Subsequently, the proposed model is transformed into mixed integer nonlinear programming (MINLP) model by duality theory. It is commonly difficult to solve in high-dimensional case. Therefore, a customized Branch-and-Cut (B&C) algorithm tailored for the GDR-GSC model is designed to handle complex MINLP problems, and improves computational efficiency and solution quality. The case study based on Apple’s sales operations in China and Malaysia demonstrates the effectiveness and superiority of the B&C algorithm in solving the GDR-GSC model. Numerical experiments show that the customized B&C algorithm can improve the average solving time by 18% while maintaining the same solution quality. Based on realistic cases, we know that horizontal cooperation can increase profits by at least 6.25%.
{"title":"Optimizing production–transportation–delivery in global supply chain with demand ambiguity by branch-and-cut algorithm","authors":"Zheng Wang , Pingyuan Dong , Ying Liu","doi":"10.1016/j.cor.2025.107293","DOIUrl":"10.1016/j.cor.2025.107293","url":null,"abstract":"<div><div>The complexity incorporated in global supply chain (GSC) means the production, transportation, and delivery are totally operating and completing in the dynamic business environment with unforeseen events. At present, there are two key challenges in the transnational supply chain network: addressing the demand ambiguity and enhancing cooperation among supply chain entities. To optimize the production–transportation–delivery decision in GSC, a novel globalized distributionally robust GSC (GDR-GSC) model with horizontal cooperation is proposed, in which the ambiguity of demand distribution is characterized by inner and outer ambiguity sets. Subsequently, the proposed model is transformed into mixed integer nonlinear programming (MINLP) model by duality theory. It is commonly difficult to solve in high-dimensional case. Therefore, a customized Branch-and-Cut (B&C) algorithm tailored for the GDR-GSC model is designed to handle complex MINLP problems, and improves computational efficiency and solution quality. The case study based on Apple’s sales operations in China and Malaysia demonstrates the effectiveness and superiority of the B&C algorithm in solving the GDR-GSC model. Numerical experiments show that the customized B&C algorithm can improve the average solving time by 18% while maintaining the same solution quality. Based on realistic cases, we know that horizontal cooperation can increase profits by at least 6.25%.</div></div>","PeriodicalId":10542,"journal":{"name":"Computers & Operations Research","volume":"185 ","pages":"Article 107293"},"PeriodicalIF":4.3,"publicationDate":"2025-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145262459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mixed integer programming (MIP) has been widely utilized to tackle a broad range of real-world decision-making problems, while its solution efficiency remains a key challenge. In this paper, we describe a novel unsupervised learning scheme for accelerating the solution of a family of MIP problems. Distinct substantially from existing learning-to-optimize methods, our proposal seeks to train an autoencoder (AE) for binary variables in an unsupervised learning fashion, using data of optimal solutions to historical instances for a parametric family of MIPs. By a deliberate design of AE architecture and exploitation of its statistical implication, we present a simple and straightforward strategy to construct a class of cutting plane constraints from the decoder parameters of an offline-trained AE. These constraints reliably enclose the optimal binary solutions of new problem instances thanks to the representation strength of AE. More importantly, their integration into the primal MIP problem of an unseen instance leads to a tightened MIP, which can be resolved at decision time using off-the-shelf solvers with much higher efficiency. Our method is applied to two benchmark problems: the batch process scheduling problem, formulated as a mixed-integer linear programming (MILP) problem, and the cart–pole system control problem, formulated as a mixed-integer quadratic programming (MIQP) problem. Comprehensive results demonstrate that our approach significantly reduces the computational cost of off-the-shelf MILP solvers while retaining a high solution quality. The codes of this work are open-sourced at https://github.com/qushiyuan/AE4BV.
{"title":"Towards an unsupervised learning scheme for efficiently solving parameterized mixed-integer programs","authors":"Shiyuan Qu , Fenglian Dong , Zhiwei Wei , Chao Shang","doi":"10.1016/j.cor.2025.107290","DOIUrl":"10.1016/j.cor.2025.107290","url":null,"abstract":"<div><div>Mixed integer programming (MIP) has been widely utilized to tackle a broad range of real-world decision-making problems, while its solution efficiency remains a key challenge. In this paper, we describe a novel unsupervised learning scheme for accelerating the solution of a family of MIP problems. Distinct substantially from existing learning-to-optimize methods, our proposal seeks to train an autoencoder (AE) for binary variables in an unsupervised learning fashion, using data of optimal solutions to historical instances for a parametric family of MIPs. By a deliberate design of AE architecture and exploitation of its statistical implication, we present a simple and straightforward strategy to construct a class of cutting plane constraints from the decoder parameters of an offline-trained AE. These constraints reliably enclose the optimal binary solutions of new problem instances thanks to the representation strength of AE. More importantly, their integration into the primal MIP problem of an unseen instance leads to a tightened MIP, which can be resolved at decision time using off-the-shelf solvers with much higher efficiency. Our method is applied to two benchmark problems: the batch process scheduling problem, formulated as a mixed-integer linear programming (MILP) problem, and the cart–pole system control problem, formulated as a mixed-integer quadratic programming (MIQP) problem. Comprehensive results demonstrate that our approach significantly reduces the computational cost of off-the-shelf MILP solvers while retaining a high solution quality. The codes of this work are open-sourced at <span><span>https://github.com/qushiyuan/AE4BV</span><svg><path></path></svg></span>.</div></div>","PeriodicalId":10542,"journal":{"name":"Computers & Operations Research","volume":"185 ","pages":"Article 107290"},"PeriodicalIF":4.3,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145262460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Inspired by real-world urban and rural distribution logistics scenarios, this study explores the dynamic crowdsourcing multi-depot pickup and delivery problem (DCMDPDP) through an online platform (OCP), where requests and crowdsourced vehicles arrive dynamically. Vehicles either collect from multiple depots for deliveries or pick up from customers to depots. To maximize the OCP’s daily total gain, the net value of completed task revenue minus vehicle compensation costs, we integrate anticipated future gains into each decision-making process and formulate the DCMDPDP as a Markov decision process. A learning-based hybrid heuristic algorithm is proposed for the DCMDPDP. Specifically, we develop an enhanced adaptive large neighborhood search algorithm leveraging the heat map to batch orders into multiple groups and assign them to depots, where the heat map is learned offline using a graph convolutional residual network with an attention mechanism model. A value learning-based algorithm is also developed to obtain optimal matches between order batches and vehicles, and near-optimal travel routes. Experimental results demonstrate that the proposed algorithm improves the OCP total gain by 46.09%, 57.13%, 0.49%, 2.45%, 1.08%, and 2.77% over six benchmarks. Furthermore, the proposed algorithm reduces unserved customers to 7.83 on average, outperforming six benchmarks by 2.19–167.52 fewer cases. Moreover, extensive experiments validate that the proposed algorithm is strongly generalizable in handling instances with varying customer sizes and different temporal, spatial, and demand distributions.
{"title":"Dynamic crowdsourcing problem in urban–rural distribution using the learning-based approach","authors":"Zongcheng Zhang , Maoliang Ran , Yanru Chen , M.I.M. Wahab , Mujin Gao , Yangsheng Jiang","doi":"10.1016/j.cor.2025.107292","DOIUrl":"10.1016/j.cor.2025.107292","url":null,"abstract":"<div><div>Inspired by real-world urban and rural distribution logistics scenarios, this study explores the dynamic crowdsourcing multi-depot pickup and delivery problem (DCMDPDP) through an online platform (OCP), where requests and crowdsourced vehicles arrive dynamically. Vehicles either collect from multiple depots for deliveries or pick up from customers to depots. To maximize the OCP’s daily total gain, the net value of completed task revenue minus vehicle compensation costs, we integrate anticipated future gains into each decision-making process and formulate the DCMDPDP as a Markov decision process. A learning-based hybrid heuristic algorithm is proposed for the DCMDPDP. Specifically, we develop an enhanced adaptive large neighborhood search algorithm leveraging the heat map to batch orders into multiple groups and assign them to depots, where the heat map is learned offline using a graph convolutional residual network with an attention mechanism model. A value learning-based algorithm is also developed to obtain optimal matches between order batches and vehicles, and near-optimal travel routes. Experimental results demonstrate that the proposed algorithm improves the OCP total gain by 46.09%, 57.13%, 0.49%, 2.45%, 1.08%, and 2.77% over six benchmarks. Furthermore, the proposed algorithm reduces unserved customers to 7.83 on average, outperforming six benchmarks by 2.19–167.52 fewer cases. Moreover, extensive experiments validate that the proposed algorithm is strongly generalizable in handling instances with varying customer sizes and different temporal, spatial, and demand distributions.</div></div>","PeriodicalId":10542,"journal":{"name":"Computers & Operations Research","volume":"185 ","pages":"Article 107292"},"PeriodicalIF":4.3,"publicationDate":"2025-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145262358","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-27DOI: 10.1016/j.cor.2025.107276
Fatih Burak Akçay, Maxence Delorme
In the strip packing problem, the objective is to pack a set of two-dimensional items into a strip of fixed width such that the total height of the packing is minimized. The current state-of-the-art exact approach for the problem uses a decomposition framework in which the main problem (MP) fixes the item abscissas and the strip height, whereas the subproblem (SP) determines whether a set of item ordinates resulting in a feasible packing exists. Even though this decomposition framework has already been used several times in the literature, implementation details were often obfuscated, limiting the outreach of the approach. We address this issue by thoroughly describing and testing various builds for this framework, investigating important features such as the way to forbid an infeasible solution in the MP (e.g., by rejecting them or through a no-good cut) and the techniques used to solve the MP and the SP. One of our findings is that a minor implementation tweak such as changing the random seed between two MP iterations can bring the same level of improvement as a more involved feature such as strengthening the no-good cuts. From our extensive experiments, we identify two versions of the framework that produce complementary results: one where the main problem is solved with integer linear programming and the other where it is solved with constraint programming. We then train a reinforcement learning agent to find the best hybridization of these two algorithms and show that the resulting approach obtains state-of-the-art results on benchmark instances.
{"title":"Solving the strip packing problem with a decomposition framework and a generic solver: Implementation, tuning, and reinforcement-learning-based hybridization","authors":"Fatih Burak Akçay, Maxence Delorme","doi":"10.1016/j.cor.2025.107276","DOIUrl":"10.1016/j.cor.2025.107276","url":null,"abstract":"<div><div>In the strip packing problem, the objective is to pack a set of two-dimensional items into a strip of fixed width such that the total height of the packing is minimized. The current state-of-the-art exact approach for the problem uses a decomposition framework in which the main problem (MP) fixes the item abscissas and the strip height, whereas the subproblem (SP) determines whether a set of item ordinates resulting in a feasible packing exists. Even though this decomposition framework has already been used several times in the literature, implementation details were often obfuscated, limiting the outreach of the approach. We address this issue by thoroughly describing and testing various builds for this framework, investigating important features such as the way to forbid an infeasible solution in the MP (e.g., by rejecting them or through a no-good cut) and the techniques used to solve the MP and the SP. One of our findings is that a minor implementation tweak such as changing the random seed between two MP iterations can bring the same level of improvement as a more involved feature such as strengthening the no-good cuts. From our extensive experiments, we identify two versions of the framework that produce complementary results: one where the main problem is solved with integer linear programming and the other where it is solved with constraint programming. We then train a reinforcement learning agent to find the best hybridization of these two algorithms and show that the resulting approach obtains state-of-the-art results on benchmark instances.</div></div>","PeriodicalId":10542,"journal":{"name":"Computers & Operations Research","volume":"185 ","pages":"Article 107276"},"PeriodicalIF":4.3,"publicationDate":"2025-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145262361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-26DOI: 10.1016/j.cor.2025.107281
Nikolai Antonov , Přemysl Šůcha , Mikoláš Janota , Jan Hůla
Existing research on single-machine scheduling is largely focused on exact algorithms, which perform well on typical instances but can significantly deteriorate on certain regions of the problem space. In contrast, data-driven approaches provide strong and scalable performance when tailored to the structure of specific datasets. Leveraging this idea, we focus on a single-machine scheduling problem where each job is defined by its weight, duration, due date, and deadline, aiming to minimize the total weight of tardy jobs. We introduce a novel data-driven scheduling heuristic that combines machine learning with problem-specific characteristics, ensuring feasible solutions, which is a common challenge for ML-based algorithms. Experimental results demonstrate that our approach significantly outperforms the state-of-the-art in terms of optimality gap, number of optimal solutions, and adaptability across varied data scenarios, highlighting its flexibility for practical applications. In addition, we conduct a systematic exploration of ML models, addressing a common gap in similar studies by offering a detailed model selection process and demonstrating why the chosen model is the best fit.
{"title":"Minimizing the weighted number of tardy jobs: data-driven heuristic for single-machine scheduling","authors":"Nikolai Antonov , Přemysl Šůcha , Mikoláš Janota , Jan Hůla","doi":"10.1016/j.cor.2025.107281","DOIUrl":"10.1016/j.cor.2025.107281","url":null,"abstract":"<div><div>Existing research on single-machine scheduling is largely focused on exact algorithms, which perform well on typical instances but can significantly deteriorate on certain regions of the problem space. In contrast, data-driven approaches provide strong and scalable performance when tailored to the structure of specific datasets. Leveraging this idea, we focus on a single-machine scheduling problem where each job is defined by its weight, duration, due date, and deadline, aiming to minimize the total weight of tardy jobs. We introduce a novel data-driven scheduling heuristic that combines machine learning with problem-specific characteristics, ensuring feasible solutions, which is a common challenge for ML-based algorithms. Experimental results demonstrate that our approach significantly outperforms the state-of-the-art in terms of optimality gap, number of optimal solutions, and adaptability across varied data scenarios, highlighting its flexibility for practical applications. In addition, we conduct a systematic exploration of ML models, addressing a common gap in similar studies by offering a detailed model selection process and demonstrating why the chosen model is the best fit.</div></div>","PeriodicalId":10542,"journal":{"name":"Computers & Operations Research","volume":"185 ","pages":"Article 107281"},"PeriodicalIF":4.3,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145217197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-26DOI: 10.1016/j.cor.2025.107289
H.W. Ljósheim, S. Jenkins, K.D. Searle, J.K. Wolff
Electric vehicles (EVs) are becoming a key mechanism to reduce emissions in the transportation industry, and hence contribute to the green transition. In this paper, we present a mathematical programming model which determines the optimal placement of EV charging stations such that chargers are placed in the most cost-efficient way possible for all stakeholders, assuming additionally that EV charging demand is inherently stochastic in nature. The model is formulated as a two-stage, continuous location–allocation model in the form of a generalised Weber problem in two dimensions. However, this formulation is non-convex and notoriously difficult to solve. We therefore propose a suitable discretisation procedure to find high quality solutions in suitable time. The discretisation procedure shows strong performance across a variety of computational experiments using randomly generated scenarios, maintaining robustness in terms of the objective value and overall solution quality.
A part of this solution procedure was entered into the 15th AIMMS-MOPTA Optimisation Modelling Competition.
{"title":"Optimal placement of electric vehicle slow-charging stations: A continuous facility location problem under uncertainty","authors":"H.W. Ljósheim, S. Jenkins, K.D. Searle, J.K. Wolff","doi":"10.1016/j.cor.2025.107289","DOIUrl":"10.1016/j.cor.2025.107289","url":null,"abstract":"<div><div>Electric vehicles (EVs) are becoming a key mechanism to reduce emissions in the transportation industry, and hence contribute to the green transition. In this paper, we present a mathematical programming model which determines the optimal placement of EV charging stations such that chargers are placed in the most cost-efficient way possible for all stakeholders, assuming additionally that EV charging demand is inherently stochastic in nature. The model is formulated as a two-stage, continuous location–allocation model in the form of a generalised Weber problem in two dimensions. However, this formulation is non-convex and notoriously difficult to solve. We therefore propose a suitable discretisation procedure to find high quality solutions in suitable time. The discretisation procedure shows strong performance across a variety of computational experiments using randomly generated scenarios, maintaining robustness in terms of the objective value and overall solution quality.</div><div>A part of this solution procedure was entered into the 15th AIMMS-MOPTA Optimisation Modelling Competition.</div></div>","PeriodicalId":10542,"journal":{"name":"Computers & Operations Research","volume":"185 ","pages":"Article 107289"},"PeriodicalIF":4.3,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145217201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-26DOI: 10.1016/j.cor.2025.107285
Gonzalo Méndez-Vogel , Sebastián Dávila-Gálvez , Pedro Jara-Moroni , Jorge Zamorano , Vladimir Marianov
This paper extends the maximum capture location problem with random utilities by incorporating the facility capacity and introducing penalties for overflows into the objective function. We propose a method that combines the key features of two state-of-the-art approaches for the uncapacitated case, which are adapted to solve the problem at hand. The first approach is a linear reformulation that extends the best-known linearization in the literature, which is based on variable substitution. The second approach is a reformulation that incorporates outer-approximation cuts and enhanced submodular cuts, solving the problem via a branch-and-cut approach. We tested the performance of the three approaches on several instances and show that the combined method outperforms each of the preceding techniques. The optimal location patterns of the model are also analysed, and it is found that considering the overflow and overflow penalties in the objective function affects the location decisions. The resulting optimal locations align more closely with practical scenarios.
{"title":"Maximum capture location problem with random utilities and overflow penalties","authors":"Gonzalo Méndez-Vogel , Sebastián Dávila-Gálvez , Pedro Jara-Moroni , Jorge Zamorano , Vladimir Marianov","doi":"10.1016/j.cor.2025.107285","DOIUrl":"10.1016/j.cor.2025.107285","url":null,"abstract":"<div><div>This paper extends the maximum capture location problem with random utilities by incorporating the facility capacity and introducing penalties for overflows into the objective function. We propose a method that combines the key features of two state-of-the-art approaches for the uncapacitated case, which are adapted to solve the problem at hand. The first approach is a linear reformulation that extends the best-known linearization in the literature, which is based on variable substitution. The second approach is a reformulation that incorporates outer-approximation cuts and enhanced submodular cuts, solving the problem via a branch-and-cut approach. We tested the performance of the three approaches on several instances and show that the combined method outperforms each of the preceding techniques. The optimal location patterns of the model are also analysed, and it is found that considering the overflow and overflow penalties in the objective function affects the location decisions. The resulting optimal locations align more closely with practical scenarios.</div></div>","PeriodicalId":10542,"journal":{"name":"Computers & Operations Research","volume":"185 ","pages":"Article 107285"},"PeriodicalIF":4.3,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145217202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-24DOI: 10.1016/j.cor.2025.107287
Wen Ma , Gedong Jiang , Nuogang Sun , Chaoqing Min , Xuesong Mei
Semiconductor manufacturing presents a highly complex Job Shop Scheduling Problem (JSP) due to the diversity and large number of processing machines, as well as the intricate manufacturing processes including batch and non-batch operations. Existing studies often either overlook batching problems or address them in oversimplified ways, failing to provide effective solutions for large-scale scheduling challenges with batch operations. For this problem, a model for the JSP involving both batching and non-batching processes in semiconductor fabs is first developed. Then, the First Come First Served (FCFS) approach, as an effective rule-based method, is employed to generate high-quality initial solutions. A tailored Constrained Genetic Algorithm (CGA) by embedding constraints to the stages of genetic algorithms is proposed to further optimize the solution. The CGA incorporates batch grouping, constrained encoding, constrained crossover and constrained mutation to effectively handle the sequential constraints of batch and non-batch processes, ensuring the generation of valid solutions. The CGA is validated using the SMT2020 and SMAT2022 datasets across various scales and scenarios. Experimental results demonstrate that the CGA outperforms FCFS, backward simulation and reinforcement learning. These results highlight the CGA’s effectiveness and robustness in solving complex scheduling problems in semiconductor manufacturing.
{"title":"Modeling and algorithm for job shop scheduling with batch operations in semiconductor fabs","authors":"Wen Ma , Gedong Jiang , Nuogang Sun , Chaoqing Min , Xuesong Mei","doi":"10.1016/j.cor.2025.107287","DOIUrl":"10.1016/j.cor.2025.107287","url":null,"abstract":"<div><div>Semiconductor manufacturing presents a highly complex Job Shop Scheduling Problem (JSP) due to the diversity and large number of processing machines, as well as the intricate manufacturing processes including batch and non-batch operations. Existing studies often either overlook batching problems or address them in oversimplified ways, failing to provide effective solutions for large-scale scheduling challenges with batch operations. For this problem, a model for the JSP involving both batching and non-batching processes in semiconductor fabs is first developed. Then, the First Come First Served (FCFS) approach, as an effective rule-based method, is employed to generate high-quality initial solutions. A tailored Constrained Genetic Algorithm (CGA) by embedding constraints to the stages of genetic algorithms is proposed to further optimize the solution. The CGA incorporates batch grouping, constrained encoding, constrained crossover and constrained mutation to effectively handle the sequential constraints of batch and non-batch processes, ensuring the generation of valid solutions. The CGA is validated using the SMT2020 and SMAT2022 datasets across various scales and scenarios. Experimental results demonstrate that the CGA outperforms FCFS, backward simulation and reinforcement learning. These results highlight the CGA’s effectiveness and robustness in solving complex scheduling problems in semiconductor manufacturing.</div></div>","PeriodicalId":10542,"journal":{"name":"Computers & Operations Research","volume":"185 ","pages":"Article 107287"},"PeriodicalIF":4.3,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145217130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}