Computers & Operations Research最新文献

{"title":"Flexible Job Shop Scheduling Problem using graph neural networks and reinforcement learning","authors":"Xi Liu ,&nbsp;Xin Chen ,&nbsp;Vincent Chau ,&nbsp;Jedrzej Musial ,&nbsp;Jacek Blazewicz","doi":"10.1016/j.cor.2025.107139","DOIUrl":"10.1016/j.cor.2025.107139","url":null,"abstract":"<div><div>The Flexible Job Shop Scheduling Problem (FJSP) is an important research topic in the field of manufacturing. Many studies have used Deep Reinforcement Learning (DRL) to learn Priority Dispatching Rules (PDR) to address the FJSP. However, compared to exact methods, there is still significant room for improvement in the quality of solutions. This paper proposes a new end-to-end DRL framework that utilizes Graph Attention Networks (GAN) to extract relevant information from the disjunctive graph. In this framework, we introduce adaptive weights when calculating attention scores, allowing the model to dynamically adjust the attention scores based on the characteristics of the input data. This helps the model more effectively capture key information within the data. To alleviate the network degradation issue and enhance model performance, the features extracted by the aforementioned model are input into a Residual Connection (RC) module for further deep feature extraction. Finally, our model is validated on generated datasets and public benchmarks, with experimental results indicating that the proposed method outperforms traditional PDR methods and the latest DRL approaches.</div></div>","PeriodicalId":10542,"journal":{"name":"Computers & Operations Research","volume":"182 ","pages":"Article 107139"},"PeriodicalIF":4.1,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144134892","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}

{"title":"Enhanced open-source scatter search algorithm for solving quadratic unconstrained binary optimization problems","authors":"Donghao Liu ,&nbsp;Wei Yang ,&nbsp;Hongpu Wang ,&nbsp;Yu Du ,&nbsp;Yang Wang ,&nbsp;Zhipeng Lü ,&nbsp;Jin-Kao Hao","doi":"10.1016/j.cor.2025.107137","DOIUrl":"10.1016/j.cor.2025.107137","url":null,"abstract":"<div><div>In recent years, quantum computing has driven significant excitement and innovation, with the Quadratic Unconstrained Binary Optimization (QUBO) model at its core. This paper introduces SATPR, a new open-source quantum-inspired metaheuristic algorithm that combines scatter search, adaptive tenure tabu search, and path-relinking. The adaptive nature of the tabu tenure, achieved through the integration of various heuristic components, enables SATPR to effectively solve different types of QUBO problem instances. Additionally, SATPR utilizes parallelism to fully leverage multi-threading capabilities, further enhancing its computational efficiency. We conducted extensive evaluations on large and challenging problem instances from four benchmark sets, including well-known QUBO and Max-Cut instances, as well as less explored random graph structures. Our results demonstrate that SATPR is highly competitive in both solution quality and computational efficiency when compared with leading metaheuristic QUBO solvers and the quantum-inspired Fixstars Amplify Annealing Engine.</div></div>","PeriodicalId":10542,"journal":{"name":"Computers & Operations Research","volume":"182 ","pages":"Article 107137"},"PeriodicalIF":4.1,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144139301","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}

{"title":"New lower bounds on the cutwidth of graphs","authors":"Jean-Claude Bermond,&nbsp;Michel Cosnard,&nbsp;David Coudert,&nbsp;Frédéric Havet","doi":"10.1016/j.cor.2025.107130","DOIUrl":"10.1016/j.cor.2025.107130","url":null,"abstract":"<div><div>Cutwidth is a parameter used in many layout problems. Determining the cutwidth of a graph is an NP-complete problem, but it is possible to design efficient branch-and-bound algorithms if good lower bounds are available for cutting branches during exploration. Knowing how to quickly evaluate good bounds in each node of the search tree is therefore crucial.</div><div>In this article, we give new lower bounds based on different graph density parameters such as the minimum, the average and the maximum average degree. Our main result is a new bound using the notion of traffic grooming on a path network, which appear to be in many cases better than bounds in the literature. Furthermore, the bound based on grooming can be computed quickly, in <span><math><mrow><mi>O</mi><mrow><mo>(</mo><mo>log</mo><mi>n</mi><mo>)</mo></mrow></mrow></math></span> time, and so is of interest to design faster branch-and-bound algorithms. Through extensive experiments, we show that this bound behaves very well compared to other bounds. Furthermore, we show how to obtain even better results when combining it with heuristics for finding dense subgraphs.</div></div>","PeriodicalId":10542,"journal":{"name":"Computers & Operations Research","volume":"182 ","pages":"Article 107130"},"PeriodicalIF":4.1,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144131074","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}

{"title":"Two-stage robust optimization for public health emergency project scheduling with uncertain activity durations","authors":"Yuchen Dong ,&nbsp;Weibo Zheng ,&nbsp;Zhiqiang Ma ,&nbsp;Zhengwen He","doi":"10.1016/j.cor.2025.107135","DOIUrl":"10.1016/j.cor.2025.107135","url":null,"abstract":"<div><div>The utilization of emergency projects, which can facilitate the coordinated scheduling of medical resources and rescue activities, offers a promising approach for absorbing disturbances, mitigating damage and achieving restoration from public healthcare catastrophes. However, the complex implementation environment in public health emergencies significantly impacts the preventive effectiveness and rescue efficiency of emergency projects. Considering the substantial uncertainty in activity durations, this study models resource allocation and schedule generation of an emergency project as a two-stage robust optimization formulation to reduce economic expenditure and minimize delayed rescue. Specifically, the preparedness stage is to minimize the pre-deployment cost of emergency resources, and a max–min objective is introduced in the response stage to optimize the deprivation cost affected by random activity durations. Then, as the robust optimization model could be reformulated in a master-submodel framework, we develop a customized column-and-constraint generation (C&amp;CG) algorithm with enhancements based on the structure of the problem and decision variables for rapid problem-solving. Besides, the algorithms are tested on randomly generated datasets, and the influences of key parameters on the algorithm performance, the resource cost and the deprivation cost of the emergency project are analyzed. Based on the computational results, the customized C&amp;CG algorithm with enhancements outperforms others and sensitivity analysis of key parameters is presented. This research provides effective decision support for public health emergency scheduling and draws management insights, validated through a real-world case study that demonstrates the model’s practical effectiveness in enhancing emergency response resilience and efficiency.</div></div>","PeriodicalId":10542,"journal":{"name":"Computers & Operations Research","volume":"182 ","pages":"Article 107135"},"PeriodicalIF":4.1,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144146881","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}

{"title":"Neural combinatorial optimization: A tutorial","authors":"Davide Angioni ,&nbsp;Claudia Archetti ,&nbsp;M. Grazia Speranza","doi":"10.1016/j.cor.2025.107102","DOIUrl":"10.1016/j.cor.2025.107102","url":null,"abstract":"<div><div>Recent advancements in deep reinforcement learning have sparked a growing interest in the application of this approach to solve combinatorial optimization (CO) problems. This paper presents neural combinatorial optimization (NCO) as a framework for constructing functions that work as heuristics for CO problems. Given the rapid expansion of the field and the increasing interest in the topic, this tutorial introduces the main techniques utilized in NCO and explores the current open issues in the field.</div><div>We define key terms and concepts related to NCO and present the latest developments, using the Knapsack Problem as a running example to complement theoretical explanations. Finally, we analyze prominent works in the field of NCO, with a focus on their application to the Traveling Salesman Problem, which serves as the most extensively studied problem in this domain.</div></div>","PeriodicalId":10542,"journal":{"name":"Computers & Operations Research","volume":"182 ","pages":"Article 107102"},"PeriodicalIF":4.1,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144139302","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}

{"title":"Coordinated scheduling optimization of quay cranes and AGVs in automated container terminals","authors":"Yuzhen Hu ,&nbsp;Min Wang ,&nbsp;Rui Min ,&nbsp;Jianxia Liu ,&nbsp;Valery F. Lukinykh ,&nbsp;Shulin Tang ,&nbsp;Da Zhao","doi":"10.1016/j.cor.2025.107147","DOIUrl":"10.1016/j.cor.2025.107147","url":null,"abstract":"<div><div>In recent years, smart ports have attracted widespread attention because of their great potential to improve port operational efficiency. Automated container terminals (ACTs), which are equipped with quay cranes (QCs) and automated guided vehicles (AGVs), play important roles in smart ports. Their coordination directly affects berthing time and port congestion, thereby influencing overall working efficiency. In this paper, we present a novel mixed-integer programming model for the coordinated scheduling of QCs and AGVs. The model aims to minimize the makespan while considering factors such as the safe working intervals of QCs, the flexible working strategy of QCs, and the relationships between adjacent tasks. In contrast to scheduling QCs and AGVs sequentially, we integrate the operations as a whole and design a two-stage solution framework for the integration. The initial solution is generated through a newly built integer programming model and dichotomy in the first stage. Variable neighborhood search (VNS) and adaptive large neighborhood search (ALNS) are integrated to improve the solution in the second stage. Optimality analysis and numerical results show the followings. (i) The coordinated scheduling schemes obtained by our method outperform the sequential scheduling schemes, reducing the makespan by an average of 15.84 time units. (ii) Considering the safe working intervals and flexible working strategies of QCs can lead to better scheduling schemes than realistic scenarios can achieve. (iii) The port’s working efficiency is maximized, and the equipment idle time is minimized when the number of AGVs is three times that of QCs in our cases. (iv) Changes in the number of AGVs have a greater effect on the makespan of coordinated operation than do changes in the quantity of QCs. Consequently, our study aims to provide a quantitative reference for the development of ACTs, which could contribute to operational efficiency improvement and sustainable development in the smart port industry.</div></div>","PeriodicalId":10542,"journal":{"name":"Computers & Operations Research","volume":"182 ","pages":"Article 107147"},"PeriodicalIF":4.1,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144146944","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}

{"title":"Replication and sequencing of unreliable jobs on m parallel machines: New results","authors":"Alessandro Agnetis ,&nbsp;Mario Benini ,&nbsp;Paolo Detti ,&nbsp;Ben Hermans ,&nbsp;Marco Pranzo ,&nbsp;Kevin Schewior","doi":"10.1016/j.cor.2025.107085","DOIUrl":"10.1016/j.cor.2025.107085","url":null,"abstract":"<div><div>This paper gives new results for the problem of sequencing <span><math><mi>m</mi></math></span> copies of <span><math><mi>n</mi></math></span> unreliable jobs (i.e., jobs that have a certain probability of being successfully carried out) on <span><math><mi>m</mi></math></span> parallel machines (one copy per machine). A job is carried out if at least one of its copies is successfully completed, in which case a certain revenue is earned. If the copy of a job fails, the corresponding machine is blocked and cannot perform the subsequently scheduled job copies. The problem is to sequence the <span><math><mi>n</mi></math></span> copies of each job on each of the <span><math><mi>m</mi></math></span> machines in order to maximize the expected revenue. For the case of <span><math><mrow><mi>m</mi><mo>=</mo><mn>2</mn></mrow></math></span>, Agnetis et al. (2022) proposed a metaheuristic approach and some upper bounding schemes. Here we address the general <span><math><mi>m</mi></math></span>-machine problem, giving a simple <span><math><mrow><mo>(</mo><mn>1</mn><mo>−</mo><mn>1</mn><mo>/</mo><mi>e</mi><mo>)</mo></mrow></math></span>-approximation algorithm, an even simpler algorithm, for which we show a tight logarithmic approximation guarantee, and an additional heuristic as well as an additional metaheuristic. We provide computational results, which, along with a new upper-bounding scheme, establish the effectiveness of our approaches in practice.</div></div>","PeriodicalId":10542,"journal":{"name":"Computers & Operations Research","volume":"183 ","pages":"Article 107085"},"PeriodicalIF":4.1,"publicationDate":"2025-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144205517","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}

{"title":"Integrating lot-sizing and pricing decisions in multi-channel markets with discrete menus of prices","authors":"Mourad Terzi ,&nbsp;Yassine Ouazene ,&nbsp;Alice Yalaoui ,&nbsp;Farouk Yalaoui","doi":"10.1016/j.cor.2025.107131","DOIUrl":"10.1016/j.cor.2025.107131","url":null,"abstract":"<div><div>This paper presents a model for coordinating lot-sizing and pricing decisions for manufacturers operating in multichannel markets with limited production capacity. Integrating these decisions is a significant challenge for manufacturers because it allows them to align their marketing and operational strategies effectively. This study addresses the application of attraction models to characterize consumers’ preferences and switching behavior between sales channels. Initially, the problem is formulated as a non-convex mixed-integer nonlinear programming (<em>MINLP</em>) model that incorporates production capacity constraints and a discrete menu of prices for each channel. To overcome the challenges of nonlinearity and nonconvexity, the problem is reformulated as an exact mixed-integer linear programming (<em>MILP</em>) model. Then, two <em>MILP</em>-based heuristics, the Fix-and-Relax and Double-Fix-and-Relax methods, are designed to solve the problem efficiently. An illustrative example demonstrates the model’s practical application and offers valuable insights for decision-makers in real-life scenarios. Furthermore, a comprehensive experimental study on 120 benchmark instances shows that the proposed solution methods achieve near-optimal solutions in less than one minute of computational time.</div></div>","PeriodicalId":10542,"journal":{"name":"Computers & Operations Research","volume":"182 ","pages":"Article 107131"},"PeriodicalIF":4.1,"publicationDate":"2025-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144124051","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}

{"title":"Time-dependent electric vehicle-drone routing problem for scheduled deliveries and on-demand pickups considering variable drone speeds and no-fly zones","authors":"Xiaoxue Ren ,&nbsp;Houming Fan ,&nbsp;Hao Fan ,&nbsp;Mengzhi Ma","doi":"10.1016/j.cor.2025.107141","DOIUrl":"10.1016/j.cor.2025.107141","url":null,"abstract":"<div><div>This paper introduces the time-dependent electric vehicle-drone routing problem for scheduled deliveries and on-demand pickups considering variable drone speeds and no-fly zones (TDEVDRP-SDOP-VDS-NZ), involving multiple electric vehicles (EVs) and unmanned aerial vehicles (UAVs) to serve scheduled delivery customer requests (SDCRs) and on-demand pickup customer requests (OPCRs) with deadlines, while considering time-dependent EV speeds, variable drone speeds and no-fly zones. For TDEVDRP-SDOP-VDS-NZ, a route-based Markov decision process (MDP) model is formulated to maximize rewards, and the offline-online heuristic algorithm (OOHA) is proposed, combining the static EV-UAV joint delivery routes with online OPCR insertions. Experimental results show a 0.23 % decrease in average reward compared to the perfect-information counterpart, with deterministic scenarios achieving an average reward higher than uncertain scenarios. OOHA outperforms two benchmark algorithms, with gaps ranging from −6.57 % to −0.31 %. As the degree of dynamism increases, both rewards and OPCR acceptance ratios decrease. Rewards drop by over 10% when the degree of dynamism rises from 0.2 to 0.5, while higher variability leads to an increase in rewards. The average online processing time remains under 0.2 s, allowing the system to quickly respond to new OPCRs in real-time. OOHA demonstrates strong stability across different customer distributions. Sensitivity analysis reveals that an increase in the number of no-fly zones decreases both rewards and the ratio of OPCRs served by UAVs, particularly the ratio, which drops by over 16%. Sensitivity analysis of UAV flight speeds finds that variable drone speeds outperform maximum and minimum speeds, with maximum and minimum speeds leading to a more than 60% drop in the ratio of OPCRs served by UAVs. TDEVDRP-SDOP-VDS-NZ, although having a longer average online processing time compared to the model of <span><span>Gu et al. (2023)</span></span>, is more in line with the actual distribution.</div></div>","PeriodicalId":10542,"journal":{"name":"Computers & Operations Research","volume":"182 ","pages":"Article 107141"},"PeriodicalIF":4.1,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144089417","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}

{"title":"Home health care routing and scheduling problems considering patient classification and outsourcing: Modeling and a solution algorithm","authors":"Xiaomeng Ma ,&nbsp;Xujin Pu ,&nbsp;Yaping Fu ,&nbsp;Kaizhou Gao ,&nbsp;Yuchen Xu","doi":"10.1016/j.cor.2025.107143","DOIUrl":"10.1016/j.cor.2025.107143","url":null,"abstract":"<div><div>Home health care (HHC) is treated as a substitute for hospitalization and plays a crucial role in relieving the pressure of medical resources resulting from population aging. HHC routing and scheduling problems have received much attention in modeling and optimization fields. This paper proposes a multi-objective HHC routing and scheduling problem considering patient classification and outsourcing operation, in which patients are classified into two types, i.e., VIP patients and ordinary patients. All the patients are assigned to an HHC center or outsourced to third-party service providers. Then, the caregivers in the HHC center are scheduled to provide services for the assigned patients. First, a mixed integer programming model with minimizing total operation cost and minimizing total tardiness is established. Second, a Q-learning-based multi-objective evolutionary algorithm with problem-specific knowledge (QMEA-K) is specially devised. At last, numerous experiments are carried out by making comparisons between QMEA-K and four algorithms and an exact solver CPLEX. The acquired results prove the effectiveness and advantages of QMEA-K in tackling the concerned problem.</div></div>","PeriodicalId":10542,"journal":{"name":"Computers & Operations Research","volume":"182 ","pages":"Article 107143"},"PeriodicalIF":4.1,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144089418","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}